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1.  Oral Delivery of Mycobacterium bovis BCG in a Lipid Formulation Induces Resistance to Pulmonary Tuberculosis in Mice  
Infection and Immunity  2003;71(1):101-108.
A lipid-based formulation has been developed for oral delivery of Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine. The formulated M. bovis BCG was fed to BALB/c mice to test for immune responses and protection against M. bovis infection. The immune responses included antigen-specific cytokine responses, spleen cell proliferation, and lymphocyte-mediated macrophage inhibition of M. bovis. Oral delivery of formulated M. bovis BCG to mice induced strong splenic gamma interferon levels and macrophage inhibition of virulent M. bovis compared with results with nonformulated M. bovis BCG. Formulated oral M. bovis BCG significantly reduced the bacterial burden in the spleen and lungs of mice following aerosol challenge with virulent M. bovis. Our data suggest that oral delivery of formulated M. bovis BCG is an effective means of inducing protective immune responses against tuberculosis. Lipid-based, orally delivered mycobacterial vaccines may be a safe and practical method of controlling tuberculosis in humans and animals.
doi:10.1128/IAI.71.1.101-108.2003
PMCID: PMC143408  PMID: 12496154
2.  IFN-γ Mediates the Rejection of Haematopoietic Stem Cells in IFN-γR1-Deficient Hosts 
PLoS Medicine  2008;5(1):e26.
Background
Interferon-γ receptor 1 (IFN-γR1) deficiency is a life-threatening inherited disorder, conferring predisposition to mycobacterial diseases. Haematopoietic stem cell transplantation (HSCT) is the only curative treatment available, but is hampered by a very high rate of graft rejection, even with intra-familial HLA-identical transplants. This high rejection rate is not seen in any other congenital disorders and remains unexplained. We studied the underlying mechanism in a mouse model of HSCT for IFN-γR1 deficiency.
Methods and Findings
We demonstrated that HSCT with cells from a syngenic C57BL/6 Ifngr1+/+ donor engrafted well and restored anti-mycobacterial immunity in naive, non-infected C57BL/6 Ifngr1−/− recipients. However, Ifngr1−/− mice previously infected with Mycobacterium bovis bacillus Calmette-Guérin (BCG) rejected HSCT. Like infected IFN-γR1-deficient humans, infected Ifngr1−/− mice displayed very high serum IFN-γ levels before HSCT. The administration of a recombinant IFN-γ-expressing AAV vector to Ifngr1−/− naive recipients also resulted in HSCT graft rejection. Transplantation was successful in Ifngr1−/− × Ifng−/− double-mutant mice, even after BCG infection. Finally, efficient antibody-mediated IFN-γ depletion in infected Ifngr1−/− mice in vivo allowed subsequent engraftment.
Conclusions
High serum IFN-γ concentration is both necessary and sufficient for graft rejection in IFN-γR1-deficient mice, inhibiting the development of heterologous, IFN-γR1-expressing, haematopoietic cell lineages. These results confirm that IFN-γ is an anti-haematopoietic cytokine in vivo. They also pave the way for HSCT management in IFN-γR1-deficient patients through IFN-γ depletion from the blood. They further raise the possibility that depleting IFN-γ may improve engraftment in other settings, such as HSCT from a haplo-identical or unrelated donor.
Claire Soudais and colleagues investigated the mechanism of rejection of hematopoietic stem cell transplants in patients with interferon-gamma receptor 1 (IFN-γR1) deficiency and show that IFN-γ is an anti-hematopoietic cytokine in vivo.
Editors' Summary
Background.
Normally, the body's immune system efficiently recognizes and kills bacteria and viruses, but in some rare inherited disorders (“primary immunodeficiencies”) part of the immune system works poorly or is missing. This leaves affected individuals susceptible to infections. People with one of these disorders—interferon-gamma receptor 1 (IFN- γR1) deficiency—are very susceptible to infections with mycobacteria. Except for Mycobacterium tuberculosis and M. leprae (which cause tuberculosis and leprosy, respectively), mycobacteria rarely cause human disease. However, most people with IFN-γR1 deficiency die during childhood from multiple, widespread mycobacterial infections, because IFN-γR1 deficiency disables a specific part of their immune system. When most bacteria enter the body, immune system cells called macrophages engulf and kill them, but mycobacteria actually multiply inside macrophages. This infection stimulates lymphocytes and other immune system cells to release IFN-γ, which binds to IFN-γR1 on uninfected macrophages, activates them, and recruits them to the infection site. Here, they form a “granuloma,” a mass of macrophages and activated lymphocytes that “walls off” the infection. Granuloma formation does not occur in patients with IFN-γR1 deficiency, so mycobacteria (including the usually benign tuberculosis vaccination strain M. bovis BCG) spread throughout the body with disastrous consequences.
Why Was This Study Done?
The only effective treatment for patients with IFN-γR1 deficiency is hematopoietic stem cell transplantation (HSCT). HSCs are the source of all the immune system cells, so transplantation of HSCs from a donor with a normal IFNGR1 gene can provide a patient who has IFN-γR1 deficiency with a new immune system that can combat mycobacterial infections. Unfortunately, in this particular immune deficiency, the new HSCs cannot engraft, even when the patient's own immune system is disabled before HSCT by intensive chemotherapy, and when the donor cells come from a close relative and are a good immunological match. In this study, the researchers have investigated why rejection is so common in IFN-γR1 deficiency using a mouse strain called C57BL/6 Ifngr1−/−—C57BL/6 denotes the genetic background of these mice and Ifngr1−/− indicates that, like human patients, these mice make no IFN-γR1.
What Did the Researchers Do and Find?
Ifngr1−/− mice, the researchers report, cannot control M. bovis BCG infections and do not form mature granulomas just like human patients with IFN-γR1 deficiency. Wild-type C57BL/6 (Ifngr1+/+) mice, however, rapidly control M. bovis BCG infections and form mature granulomas. Ifngr1+/+ HSC transplanted into mycobacteria-free Ifngr1−/− mice survived well and protected the mice against later mycobacterial challenge but Ifngr1−/− mice infected with M. bovis BCG before HSCT rejected the transplanted HSCs. Mycobacteria-infected Ifngr1−/− mice and human patients with IFN-γR1 deficiency have blood high levels of IFN-γ. Could this be responsible for HSCT rejection? To find out, the researchers expressed IFN-γ in uninfected Ifngr1−/− mice before HSCT. As in infected mice, these grafts failed. Conversely, transplanted HSCs survived when transplanted into Ifngr1−/− mice that had been genetically altered to express no IFN-γ, even when these mice were infected with M. bovis BCG before transplantation. Finally, when the researchers used antibodies (proteins made by the immune system that recognize specific molecules) to remove circulating IFN-γ from infected Ifngr1−/− mice, HSCT worked well in the animals with the lowest IFN-γ levels.
What Do These Findings Mean?
These findings indicate that in a mouse model of IFN-γR1 deficiency, high circulating IFN-γ concentrations drive the rejection of transplanted HSCs and prevent the development of antimycobacterial immunity, probably by directly killing the transplanted cells and/or stopping them multiplying. They also suggest how HSCT could be improved in patients with IFN-γR1 deficiency although, as with all animal studies, the situation in people might turn out to be very different. Importantly, antibodies that reduce circulating IFN-γ are already being used to treat other human immune diseases, so the clinical use of these antibodies in patients with IFN-γ deficiency before HSCT is feasible. Finally, the researchers speculate that the use of IFN-γ–depleting antibodies might be beneficial in other situations where HSCT often fails such as when a close relative is not available as a donor. However, this possibility will need to be thoroughly tested in mice before human clinical trials can be started.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050026.
General information about primary immunodeficiencies is available from the US National Institute of Child Health and Human Development
Online Mendelian Inheritance in Man (OMIM) provides information about familial predisposition to mycobacterial disease
Wikipedia has pages on hematopoietic stem cell transplantation and on interferon-γ (note that Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
The Human Genetics of Infectious Diseases Lab focuses on the genetic basis of predicposition or resistance to infectious diseases in humans
doi:10.1371/journal.pmed.0050026
PMCID: PMC2214797  PMID: 18232731
3.  Safety evaluation of the antimicrobial peptide bovicin HC5 orally administered to a murine model 
BMC Microbiology  2013;13:69.
Background
Bovicin HC5 is an antimicrobial peptide that shows a broad spectrum of activity and potential for biotechnological and therapeutic applications. To gain insight about the safety of bovicin HC5 application, the histological and immunostimulatory effects of orally administrated bovicin HC5 to BALB/c mice were evaluated. BALB/c mice were divided into three groups: negative control (NC group); mice given purified bovicin HC5 (Bov group); mice given ovalbumin (positive control, PC group; a murine model of enteropathy). The mice were initially pre-sensitized, and PBS, bovicin HC5 or ovalbumin were administered for 30 days by daily gavages. Histological and morphometric analysis were performed and the relative expression of cytokines was analyzed by real-time RT-PCR.
Results
The oral administration of bovicin HC5 to BALB/c mice reduced weight gain and caused alterations in the small intestine, although absorptive changes have not been detected. The number of total goblet cells and the mucopolysaccharides production were not affected by bovicin HC5 administration. A hypertrophy of Paneth cells and an increase in the number of mitotic cells were observed in Bov group, while the number of mast cells remained unaltered. Increased expression of TNF-α, INF-γ and IL-12 was observed in the small intestine upon bovicin HC5 administration.
Conclusion
Bovicin HC5 has only minor effects on intestinal permeability and did not elicit an allergenic response upon oral administration to animal models. Considering the low in vivo toxicity of bovicin HC5, it might be a good candidate for enteral applications.
doi:10.1186/1471-2180-13-69
PMCID: PMC3639230  PMID: 23537130
Bacteriocin; Lantibiotic; Streptococcus bovis HC5; BALB/c mice; Ovalbumin
4.  Mycobacterium bovis BCG-induced protection against cutaneous and systemic Leishmania major infections of mice. 
Infection and Immunity  1987;55(7):1707-1714.
We examined the protective effects of Mycobacterium bovis bacillus Calmette-Guérin (BCG) administration on Leishmania major infections of BALB/c and P/J mice. There were two treatment protocols. In the first, the footpads of naive animals were inoculated with mixtures of L. major and BCG (viable or heat killed) or the soluble mycobacterial antigen, purified protein derivative. Viable BCG, but not heat-killed BCG or purified protein derivative, inoculated with L. major amastigotes into the footpads of naive BALB/c or P/J mice protected these animals from the metastatic spread of parasites to the viscera and from ensuing lethal systemic infection. This treatment also induced cures of the cutaneous lesions of P/J mice but not of BALB/c mice. In the second protocol, we induced an immune response to BCG before inoculation of L. major. BCG given intraperitoneally 10 days before infection of footpads with leishmania offered protection against the metastatic spread of amastigotes in both P/J and BALB/c mice, regardless of intralesional treatment, and modulated the severity of cutaneous infection by 30 to 50%. Inoculation of a mixture of viable BCG and L. major amastigotes into BCG-immune mice completely protected both BALB/c and P/J strains from cutaneous disease; we recovered no parasites from the inoculated footpads of these animals. Furthermore, each of the nonspecifically protected mice of both the BALB/c and P/J strains developed immunity to rechallenge with viable L. major. Injection of amastigotes at a site remote from the original lesion, the contralateral footpad, resulted in the complete clearance of parasites in the inoculum with no evidence of either cutaneous or systemic disease over an extended observation period.
PMCID: PMC260582  PMID: 3298065
5.  Bactofencin A, a New Type of Cationic Bacteriocin with Unusual Immunity 
mBio  2013;4(6):e00498-13.
ABSTRACT
Bacteriocin production is an important probiotic trait of intestinal bacteria. In this study, we identify a new type of bacteriocin, bactofencin A, produced by a porcine intestinal isolate Lactobacillus salivarius DPC6502, and assess its potency against pathogenic species including Staphylococcus aureus and Listeria monocytogenes. Genome sequencing of the bacteriocin producer revealed bfnA, which encodes the mature and highly basic (pI 10.59), 22-amino-acid defensin-like peptide. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectral analysis determined that bactofencin A has a molecular mass of 2,782 Da and contains two cysteine residues that form an intramolecular disulfide bond. Although an ABC transporter and transport accessory protein were also present within the bacteriocin gene cluster, a classical bacteriocin immunity gene was not detected. Interestingly, a dltB homologue was identified downstream of bfnA. DltB is usually encoded within the dlt operon of many Gram-positive bacteria. It is responsible for d-alanylation of teichoic acids in the cell wall and has previously been associated with bacterial resistance to cationic antimicrobial peptides. Heterologous expression of this gene conferred bactofencin A-specific immunity on sensitive strains of L. salivarius and S. aureus (although not L. monocytogenes), establishing its role in bacteriocin immunity. An analysis of the distribution of bfnA revealed that it was present in four additional isolates derived from porcine origin and absent from five human isolates, suggesting that its distribution is host specific. Given its novelty, we anticipate that bactofencin A represents the prototype of a new class of bacteriocins characterized as being cationic, with a DltB homologue providing a cognate immunity function.
IMPORTANCE
This study describes the identification, purification, and characterization of bactofencin A, a novel type of bacteriocin produced by L. salivarius DPC6502. Interestingly, bactofencin A is not similar to any other known bacteriocin but instead shares similarity with eukaryotic cationic antimicrobial peptides, and here, we demonstrate that it inhibits two medically significant pathogens. Genome sequence analysis of the producing strain also revealed the presence of an atypical dltB homologue in the bacteriocin gene cluster, which was lacking a classical bacteriocin immunity gene. Furthermore, cloning this gene rendered sensitive strains resistant to the bacteriocin, thereby establishing its role in providing cognate bacteriocin immunity. Four additional L. salivarius isolates, also of porcine origin, were found to contain the bacteriocin biosynthesis genes and successfully produced bactofencin A, while these genes were absent from five human-derived strains investigated.
doi:10.1128/mBio.00498-13
PMCID: PMC3809560  PMID: 24169573
6.  Use of ethanol extract of Mycobacterium bovis for detection of specific antibodies in sera of farmed red deer (Cervus elaphus) with bovine tuberculosis 
Background
Bovine tuberculosis (bTB) in wildlife species poses a threat to domestic livestock in many situations. Control programs for bTB in livestock depend on testing and slaughtering the positive animals; however, the currently available diagnostic tests often have poor specificity. In our previous study, we developed a specific and sensitive enzyme linked immunosorbent assay (ELISA) for another mycobacterial disease – Johne’s disease, using surface antigens of Mycobacterium avium ssp. paratuberculosis (MAP) extracted by briefly agitating the bacilli in 80% ethanol solution. The ELISA test was named ethanol vortex ELISA (EVELISA). The objective of this study is to examine whether EVELISA technique could be used to specifically detect anti-Mycobacterium bovis (M. bovis) antibodies in the serum of M. bovis-infected farmed red deer (Cervus elaphus). We tested a total of 45 red deer serum samples, divided in 3 groups – uninfected animals (n = 15), experimentally infected with M. bovis (n = 15) and experimentally infected with MAP (n = 15).
Results
The presence of anti-M. bovis antibodies was tested using an ethanol extract of M. bovis. Without absorption of anti-MAP cross reactive antibodies, it was found that 13 out of the 15 MAP-infected animals showed high antibody binding. Using heat killed MAP as an absorbent of cross reactive antibodies, anti-M. bovis antibodies were detected in 86.7% of M. bovis-infected animals with minor false positive results caused by MAP infection.
Conclusions
The results from this study suggest that EVELISA may form a basis for a sensitive and specific test for the diagnosis of bTB in farmed red deer.
doi:10.1186/1746-6148-9-256
PMCID: PMC3878491  PMID: 24341485
Bovine tuberculosis; ELISA; Mycobacterium bovis; Red deer
7.  The Continuing Story of Class IIa Bacteriocins 
Many bacteria produce antimicrobial peptides, which are also referred to as peptide bacteriocins. The class IIa bacteriocins, often designated pediocin-like bacteriocins, constitute the most dominant group of antimicrobial peptides produced by lactic acid bacteria. The bacteriocins that belong to this class are structurally related and kill target cells by membrane permeabilization. Despite their structural similarity, class IIa bacteriocins display different target cell specificities. In the search for new antibiotic substances, the class IIa bacteriocins have been identified as promising new candidates and have thus received much attention. They kill some pathogenic bacteria (e.g., Listeria) with high efficiency, and they constitute a good model system for structure-function analyses of antimicrobial peptides in general. This review focuses on class IIa bacteriocins, especially on their structure, function, mode of action, biosynthesis, bacteriocin immunity, and current food applications. The genetics and biosynthesis of class IIa bacteriocins are well understood. The bacteriocins are ribosomally synthesized with an N-terminal leader sequence, which is cleaved off upon secretion. After externalization, the class IIa bacteriocins attach to potential target cells and, through electrostatic and hydrophobic interactions, subsequently permeabilize the cell membrane of sensitive cells. Recent observations suggest that a chiral interaction and possibly the presence of a mannose permease protein on the target cell surface are required for a bacteria to be sensitive to class IIa bacteriocins. There is also substantial evidence that the C-terminal half penetrates into the target cell membrane, and it plays an important role in determining the target cell specificity of these bacteriocins. Immunity proteins protect the bacteriocin producer from the bacteriocin it secretes. The three-dimensional structures of two class IIa immunity proteins have been determined, and it has been shown that the C-terminal halves of these cytosolic four-helix bundle proteins specify which class IIa bacteriocin they protect against.
doi:10.1128/MMBR.00016-05
PMCID: PMC1489543  PMID: 16760314
8.  Porphyromonas gingivalis virulence in mice: induction of immunity to bacterial components. 
Infection and Immunity  1992;60(4):1455-1464.
Selected cell envelope components of Porphyromonas gingivalis were tested in a BALB/c mouse model in an attempt to elucidate further the outer membrane components of this putative oral pathogen that might be considered as virulence factors in host tissue destruction. Lipopolysaccharide (LPS), outer membrane, and outer membrane vesicles of P. gingivalis W50, ATCC 53977, and ATCC 33277 were selected to examine an immunological approach for interference with progressing tissue destruction. Mice were actively immunized with heat-killed (H-K) or Formalin-killed (F-K) whole cells or with the outer membrane fraction, LPS, or outer membrane vesicles of the invasive strain P. gingivalis W50. The induction of invasive spreading lesions with tissue destruction and lethality were compared among different immunization groups in normal, dexamethasone-treated (dexamethasone alters neutrophil function at the inflammatory site), and galactosamine-sensitized (galactosamine sensitization increases endotoxin sensitivity) mice after challenge infection with the homologous strain (W50) and heterologous strains (ATCC 53977 and ATCC 33277). Enzyme-linked immunosorbent assay analyses revealed significantly elevated immunoglobulin G and M antibody responses after immunization with H-K or F-K cells or the outer membrane fraction compared with those of nonimmunized mice. The killed whole-cell vaccines provided significantly greater protection against challenge infection in normal mice (decreased lesion size and death) than did either the outer membrane fraction or LPS immunization. The lesion development observed in dexamethasone-pretreated mice was significantly enhanced compared with that of normal mice after challenge with P. gingivalis. Immunization with P. gingivalis W50 provided less protection against heterologous challenge infection with P. gingivalis ATCC 53977; however, some species-specific antigens were recognized and induced protective immunity. Only viable P. gingivalis induced a spreading lesion in normal, dexamethasone-treated, or galactosamine-sensitized mice; F-K or H-K bacteria did not induce lesions. The F-K and outer membrane vesicle immunization offered greater protection from lesion induction than did the H-K immunogen after challenge infection simultaneous with galactosamine sensitization. The H-K cell challenge with galactosamine sensitization produced 100% mortality without lesion induction, suggesting that LPS or LPS-associated outer membrane molecules were functioning like endotoxin. Likewise, P. gingivalis W50 LPS (1 micrograms per animal) administered intravenously produced 80% mortality in galactosamine-sensitized mice. In contrast to the effects of immunization on lesion development, immunization with H-K or F-K cells or LPS provided no protection against intravenous challenge with LPS; 100% of the mice died from acute endotoxin toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMCID: PMC257018  PMID: 1312516
9.  Prevention of SIV Rectal Transmission and Priming of T Cell Responses in Macaques after Local Pre-exposure Application of Tenofovir Gel 
PLoS Medicine  2008;5(8):e157.
Background
The rectum is particularly vulnerable to HIV transmission having only a single protective layer of columnar epithelium overlying tissue rich in activated lymphoid cells; thus, unprotected anal intercourse in both women and men carries a higher risk of infection than other sexual routes. In the absence of effective prophylactic vaccines, increasing attention is being given to the use of microbicides and preventative antiretroviral (ARV) drugs. To prevent mucosal transmission of HIV, a microbicide/ARV should ideally act locally at and near the virus portal of entry. As part of an integrated rectal microbicide development programme, we have evaluated rectal application of the nucleotide reverse transcriptase (RT) inhibitor tenofovir (PMPA, 9-[(R)-2-(phosphonomethoxy) propyl] adenine monohydrate), a drug licensed for therapeutic use, for protective efficacy against rectal challenge with simian immunodeficiency virus (SIV) in a well-established and standardised macaque model.
Methods and Findings
A total of 20 purpose-bred Indian rhesus macaques were used to evaluate the protective efficacy of topical tenofovir. Nine animals received 1% tenofovir gel per rectum up to 2 h prior to virus challenge, four macaques received placebo gel, and four macaques remained untreated. In addition, three macaques were given tenofovir gel 2 h after virus challenge. Following intrarectal instillation of 20 median rectal infectious doses (MID50) of a noncloned, virulent stock of SIVmac251/32H, all animals were analysed for virus infection, by virus isolation from peripheral blood mononuclear cells (PBMC), quantitative proviral DNA load in PBMC, plasma viral RNA (vRNA) load by sensitive quantitative competitive (qc) RT-PCR, and presence of SIV-specific serum antibodies by ELISA. We report here a significant protective effect (p = 0.003; Fisher exact probability test) wherein eight of nine macaques given tenofovir per rectum up to 2 h prior to virus challenge were protected from infection (n = 6) or had modified virus outcomes (n = 2), while all untreated macaques and three of four macaques given placebo gel were infected, as were two of three animals receiving tenofovir gel after challenge. Moreover, analysis of lymphoid tissues post mortem failed to reveal sequestration of SIV in the protected animals. We found a strong positive association between the concentration of tenofovir in the plasma 15 min after rectal application of gel and the degree of protection in the six animals challenged with virus at this time point. Moreover, colorectal explants from non-SIV challenged tenofovir-treated macaques were resistant to infection ex vivo, whereas no inhibition was seen in explants from the small intestine. Tissue-specific inhibition of infection was associated with the intracellular detection of tenofovir. Intriguingly, in the absence of seroconversion, Gag-specific gamma interferon (IFN-γ)-secreting T cells were detected in the blood of four of seven protected animals tested, with frequencies ranging from 144 spot forming cells (SFC)/106 PBMC to 261 spot forming cells (SFC)/106 PBMC.
Conclusions
These results indicate that colorectal pretreatment with ARV drugs, such as tenofovir, has potential as a clinically relevant strategy for the prevention of HIV transmission. We conclude that plasma tenofovir concentration measured 15 min after rectal administration may serve as a surrogate indicator of protective efficacy. This may prove to be useful in the design of clinical studies. Furthermore, in vitro intestinal explants served as a model for drug distribution in vivo and susceptibility to virus infection. The finding of T cell priming following exposure to virus in the absence of overt infection is provocative. Further studies would reveal if a combined modality microbicide and vaccination strategy is feasible by determining the full extent of local immune responses induced and their protective potential.
Martin Cranage and colleagues find that topical tenofovir gel can protect against rectal challenge with SIV in a macaque model, and can permit the induction of SIV-specific T cell responses.
Editors' Summary
Background.
About 33 million people are now infected with the human immunodeficiency virus (HIV), which causes AIDS by killing immune system cells. As yet, there is no cure for AIDS, although HIV infections can be held in check with antiretroviral drugs. Also, despite years of research, there is no vaccine available that effectively protects people against HIV infection. So, to halt the AIDS epidemic, other ways of preventing the spread of HIV are being sought. For example, pre-exposure treatment (prophylaxis) with antiretroviral drugs is being investigated as a way to prevent HIV transmission. In addition, because HIV is often spread through heterosexual penile-to-vaginal sex with an infected partner, several vaginal microbicides (compounds that protect against HIV when applied inside the vagina) are being developed, some of which contain antiretroviral drugs.
Why Was This Study Done?
Because HIV can cross the membranes that line the mouth and the rectum (the lower end of the large intestine that connects to the anus) in addition to the membrane that lines the vagina, HIV transmission can also occur during oral and anal sex. The lining of the rectum in particular is extremely thin and overlies tissues rich in activated T cells (the immune system cells that HIV targets), so unprotected anal intercourse carries a high risk of HIV infection. Anal intercourse is common among men who have sex with men but is also more common in heterosexual populations than is generally thought. Tenofovir (an antiretroviral drug that counteracts HIV after it has entered human cells) given by mouth partly protects macaques against rectal infection with simian immunodeficiency virus (SIV; a virus that induces AIDS in monkeys and apes) so the researchers wanted to know whether this drug might be effective against rectal SIV infection if applied at the site where the virus enters the body.
What Did the Researchers Do and Find?
To answer this question, the researchers rectally infected several macaques with SIV up to 2 h after rectal application of a gel containing tenofovir, after rectal application of a gel not containing the drug, or after no treatment. In addition, a few animals were treated with the tenofovir gel after the viral challenge. Most of the animals given the tenofovir gel before the viral challenge were partly or totally protected from SIV infection, whereas all the untreated animals and most of those treated with the placebo gel or with the drug-containing gel after the viral challenge became infected with SIV. High blood levels of tenofovir 15 min after its rectal application correlated with protection from viral infection. The researchers also collected rectal and small intestine samples from tenofovir-treated macaques that had not been exposed to SIV and asked which samples were resistant to SIV infection in laboratory dishes. They found that only the rectal samples were resistant to infection and only rectal cells contained tenofovir. Finally, activated T cells that recognized an SIV protein were present in the blood of some of the animals that were protected from SIV infection by the tenofovir gel.
What Do These Findings Mean?
These findings, although based on experiments in only a few animals, suggest that rectal treatment with antiretroviral drugs before rectal exposure to HIV might prevent rectal HIV transmission in people. However, results from animal experiments do not always reflect what happens in people. Indeed, clinical trials of a potential vaginal microbicide that worked well in macaques were halted recently because women using the microbicide had higher rates of HIV infection than those using a control preparation. The finding that immune-system activation can occur in the absence of overt infection in animals treated with the tenofovir gel additionally suggests that a combination of a local antiretroviral/microbicide and vaccination might be a particularly effective way to prevent HIV transmission. However, because HIV targets activated T cells, viral rechallenge experiments must be done to check that the activated T cells induced by the virus in the presence of tenofovir do not increase the likelihood of infection upon re-exposure to HIV before this potential microbicide is tried in people.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050157.
Read the accompanying PLoS Medicine Perspective by Florian Hladik
An overview of HIV infection and AIDS is available from the US National Institute of Allergy and Infectious Diseases
HIVInSite has comprehensive information on all aspects of HIV/AIDS, including an article on safer sex, which includes information on the risks associated with specific types of sex and on microbicides and other methods to prevent the sexual transmission of HIV
Information on all aspects of HIV/AIDS is available from Avert, an international AIDS charity, including information on HIV prevention and on microbicides
The World Health Organization has a fact sheet on microbicides
The UK charity NAM also provides detailed information on microbicides
PrEP Watch is a comprehensive information source on pre-exposure prophylaxis for HIV prevention
Global Campaign for Microbicides is an international coalition of organisations dedicated to accelerating access to new HIV prevention options
doi:10.1371/journal.pmed.0050157
PMCID: PMC2494562  PMID: 18684007
10.  Differential production of interleukin-12 mRNA by murine macrophages in response to viable or killed Salmonella spp. 
Infection and Immunity  1996;64(4):1154-1160.
The use of attenuated Salmonella spp. as live oral vaccine carriers fo r foreign antigens has been extensively studied. We have shown that appropriately prepared nonviable organisms are as effective as viable organisms in eliciting humoral immune responses against a foreign antigen delivered by these vectors. It is not clear how strain viability affects the development of a cell-mediated immune response. In the present study, we demonstrate that BALB/c mice orally immunized with viable attenuated Salmonella spp. were protected against subsequent challenge while animals immunized with killed organisms were not. Protection was correlated with increased production of interleukin-12 (IL-12) p40 mRNA in the Peyer's patches within hours of oral administration. Peritoneal macrophages from lipopolysaccharide (LPS)-responsive and LPS-unresponsive mice were also examined for production of IL-12 p40 mRNA following exposure to the viable or killed attenuated Salmonella carrier. There was dramatic upregulation of IL-12 p40 mRNA following exposure of macrophages to either viable or killed organisms. By 4 h postexposure, viable organisms had induced a 27-fold increase in IL-12 p40 mRNA levels while killed organisms had induced a 9-fold increase in IL-12 p40 mRNA levels. This was observed in macrophages isolated from both LPS-responsive and unresponsive mice. The higher levels of IL-12 induced by viable Salmonella spp. may result in the development of a Th1 response and cell mediated immunity, while the lower levels of IL-12 induced by killed Salmonella spp. may not be sufficient to promote a Th1 response.
PMCID: PMC173897  PMID: 8606072
11.  Mycobacterium bovis BCG infection severely delays Trichuris muris expulsion and co-infection suppresses immune responsiveness to both pathogens 
BMC Microbiology  2014;14:9.
Background
The global epidemiology of parasitic helminths and mycobacterial infections display extensive geographical overlap, especially in the rural and urban communities of developing countries. We investigated whether co-infection with the gastrointestinal tract-restricted helminth, Trichuris muris, and the intracellular bacterium, Mycobacterium bovis (M. bovis) BCG, would alter host immune responses to, or the pathological effect of, either infection.
Results
We demonstrate that both pathogens are capable of negatively affecting local and systemic immune responses towards each other by modifying cytokine phenotypes and by inducing general immune suppression. T. muris infection influenced non-specific and pathogen-specific immunity to M. bovis BCG by down-regulating pulmonary TH1 and Treg responses and inducing systemic TH2 responses. However, co-infection did not alter mycobacterial multiplication or dissemination and host pulmonary histopathology remained unaffected compared to BCG-only infected mice. Interestingly, prior M. bovis BCG infection significantly delayed helminth clearance and increased intestinal crypt cell proliferation in BALB/c mice. This was accompanied by a significant reduction in systemic helminth-specific TH1 and TH2 cytokine responses and significantly reduced local TH1 and TH2 responses in comparison to T. muris-only infected mice.
Conclusion
Our data demonstrate that co-infection with pathogens inducing opposing immune phenotypes, can have differential effects on compartmentalized host immune protection to either pathogen. In spite of local and systemic decreases in TH1 and increases in TH2 responses co-infected mice clear M. bovis BCG at the same rate as BCG only infected animals, whereas prior mycobacterial infection initiates prolonged worm infestation in parallel to decreased pathogen-specific TH2 cytokine production.
doi:10.1186/1471-2180-14-9
PMCID: PMC3898725  PMID: 24433309
Helminth; Co-infection; Mycobacteria; Tuberculosis
12.  Colonization and infection of athymic and euthymic germfree mice by Campylobacter jejuni and Campylobacter fetus subsp. fetus. 
Infection and Immunity  1986;53(2):378-383.
Human clinical strains of Campylobacter jejuni and Campylobacter fetus subsp. fetus colonized the gastrointestinal tracts of both athymic (nu/nu) and euthymic (+/nu) germfree mice (BALB/c). Viable Campylobacter spp. (10(9) to 10(10) CFU/g [dry weight] of cecum and colon contents) were isolated on day 3 after oral challenge, and similar large numbers of viable cells were evident at several intervals during a 10-month experiment. The stomachs and upper small intestines of nu/nu and +/nu mice that were monoassociated for 224 days with C. jejuni 45100 contained 3 to 4 logs fewer viable bacteria than did their ceca or colons. Athymic mice that were monoassociated for 224 days with C. fetus subsp. fetus had 2 to 3 logs more viable Campylobacter spp. in their upper gastrointestinal tracts than did their +/nu littermates. Large viable populations (approximately 10(9)/g of contents) of C. fetus subsp. fetus were in the ceca and colons of both nu/nu and +/nu mice. All C. jejuni strains used in this study chronically infected the mesenteric lymph nodes of both nu/nu and +/nu mice. C. jejuni strains 24 and INN 73-83, which were cytotoxic for Chinese hamster ovary cells in vitro, were also more frequently isolated from the livers, spleens, and kidneys of nu/nu mice than was the weak cytotoxin-producing strain 45100. Additionally, heat-labile-enterotoxin-producing C. jejuni INN 73-83 was recovered more frequently from the internal organs of monoassociated +/nu mice than were any other Campylobacter spp. tested. Natural gastrointestinal colonization of neonatal nu/nu and +/nu mice (born to Campylobacter-colonized mothers) with Campylobacter spp. appeared to be delayed until approximately 1 to 2 weeks after birth. Conventionalization of C. jejuni 45100-monoassociated BALB/c mice with a complex mouse fecal microflora eliminated viable C. jejuni from the mesenteric lymph nodes by day 14 and from the cecum by day 78. These findings show that the gnotobiotic BALB/c mouse is a new model for studying acute and chronic host-Campylobacter sp. interactions.
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PMCID: PMC260886  PMID: 3733222
13.  Antibody response to a sterile filtered PPD tuberculin in M. bovis infected and M. bovis sensitized cattle 
Background
Bovine tuberculosis, caused by Mycobacterium bovis, afflicts approximately 50 million cattle worldwide and is detected by the tuberculin skin test (TST). While it has long been recognized that purified protein derivative (PPD) tuberculin is composed of a mixture of M. bovis derived protein components, little is known about the quality, relative quantity and identity of the proteins that make up PPD tuberculin. We manufactured a sterile filtered PPD tuberculin (SF-PPD) from a nine-week-old M. bovis culture supernatant in order to characterise the culture filtrate proteins (CFP) which make up M. bovis PPD tuberculin and to compare the antibody response of M. bovis infected versus M. bovis sensitized cattle.
Results
SF-PPD resolved into approximately 200 discrete spots using two-dimensional polyacrylamide gel electrophoresis (2-DE) while fewer than 65 spots could be discerned from 2-DE gels of tuberculin derived from autoclaved culture supernatant. Two dimensional Western blot analyses indicated that sera from M. bovis sensitized cattle recognized additional SF-PPD antigens as compared to M. bovis infected cattle at seven weeks post infection/sensitization. However, application of a comparative tuberculin skin test resulted in an antibody boosting response to the same set of M. bovis CFPs in both the M. bovis infected and M. bovis sensitized cattle.
Conclusions
We concluded that it is the heat sterilization of the M. bovis CFPs that causes severe structural changes to the M. bovis proteins. This work suggests that M. bovis infected cattle and cattle artificially sensitized to M. bovis with an injection of heat killed cells exhibit similar antibody responses to M. bovis antigens.
doi:10.1186/1746-6148-6-50
PMCID: PMC2994848  PMID: 21062483
14.  Antigen provoking gamma interferon production in response to Mycobacterium bovis BCG and functional difference in T-cell responses to this antigen between viable and killed BCG-immunized mice. 
Infection and Immunity  1994;62(10):4396-4403.
It has been shown that gamma interferon (IFN-gamma)-producing CD4+ T cells, which are generated only by immunization with viable bacteria, exert a significant role in protective immunity against mycobacteria in mice. In this study, we have tried to determine the antigen recognized by the T cells in search of a possible protective antigen. T cells from viable Mycobacterium bovis BCG-immunized mice were stimulated with several antigens, and IFN-gamma production was measured. Purified protein derivative and viable and killed BCG lysates caused significant IFN-gamma production, and almost the same level of IFN-gamma activity was detected in both groups stimulated with viable and killed BCG lysates. However, heat shock protein (HSP) 65 and HSP 70 were not a major antigen for IFN-gamma production. The antigen provoking IFN-gamma production is localized mainly in the membrane fraction of BCG cells, and the approximate molecular size was 18 kDa. On the other hand, T cells from killed BCG-immunized mice never responded to this antigen for IFN-gamma production, whereas they could mount a delayed-type hypersensitivity response. These results showed that the antigen provoking IFN-gamma production was present in killed as well as viable BCG. In addition to the antigen presentation by antigen-presenting cells, some kinds of differentiation factor (such as monokines) that are produced only by stimulation with viable cells seemed to be necessary for the development of IFN-gamma-producing T cells.
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PMCID: PMC303122  PMID: 7927701
15.  Enhanced Immunological Memory Responses to Listeria monocytogenes in Rodents, as Measured by Delayed-Type Hypersensitivity (DTH), Adoptive Transfer of DTH, and Protective Immunity, following Lactobacillus casei Shirota Ingestion 
We have investigated the effect of orally administered Lactobacillus casei Shirota (L. casei) on immunological memory, as measured by delayed-type hypersensitivity (DTH) and acquired cellular resistance (ACR). The studies were performed in animal models in which the animals were rendered immune by a primary Listeria monocytogenes infection. It was shown that orally administered viable L. casei, and not heat-killed L. casei, enhanced significantly the antigen-specific DTH at 24 and 48 h in Wistar rats, Brown Norway rats, and BALB/c mice in a time- and dose-dependent fashion. L. casei had to be administered at least 3 days prior to the DTH assay at a daily dose of 109 CFU in order to induce significant effects. Long-term administration of 109 CFU of viable L. casei resulted in enhanced ACR, as demonstrated by reduced L. monocytogenes counts in the spleen and liver and diminished serum alanine aminotransferase activity after reinfection. Enhancement of cell-mediated immunological immune responses by L. casei was further established in an adoptive transfer study. Naïve recipient BALB/c mice, which were infused with nonadherent, immunized spleen cells from L. casei-fed donor BALB/c mice, showed significantly enhanced DTH responses at 24 and 48 h compared to recipient mice which received spleen cells from control donor mice. In conclusion, orally administered L. casei enhanced cell-mediated immunological memory responses. The effects relied on lactobacillus dose and viability as well as timing of supplementation and, further, appeared to be independent of host species or genetic background.
doi:10.1128/CDLI.10.1.59-65.2003
PMCID: PMC145274  PMID: 12522040
16.  Effect of Lactobacillus salivarius Bacteriocin Abp118 on the Mouse and Pig Intestinal Microbiota 
PLoS ONE  2012;7(2):e31113.
Lactobacilli are Gram-positive bacteria that are a subdominant element in the human gastrointestinal microbiota, and which are commonly used in the food industry. Some lactobacilli are considered probiotic, and have been associated with health benefits. However, there is very little culture-independent information on how consumed probiotic microorganisms might affect the entire intestinal microbiota. We therefore studied the impact of the administration of Lactobacillus salivarius UCC118, a microorganism well characterized for its probiotic properties, on the composition of the intestinal microbiota in two model animals. UCC118 has anti-infective activity due to production of the bacteriocin Abp118, a broad-spectrum class IIb bacteriocin, which we hypothesized could impact the microbiota. Mice and pigs were administered wild-type (WT) L. salivarius UCC118 cells, or a mutant lacking bacteriocin production. The microbiota composition was determined by pyrosequencing of 16S rRNA gene amplicons from faeces. The data show that L. salivarius UCC118 administration had no significant effect on proportions of major phyla comprising the mouse microbiota, whether the strain was producing bacteriocin or not. However, L. salivarius UCC118 WT administration led to a significant decrease in Spirochaetes levels, the third major phylum in the untreated pig microbiota. In both pigs and mice, L. salivarius UCC118 administration had an effect on Firmicutes genus members. This effect was not observed when the mutant strain was administered, and was thus associated with bacteriocin production. Surprisingly, in both models, L. salivarius UCC118 administration and production of Abp118 had an effect on Gram-negative microorganisms, even though Abp118 is normally not active in vitro against this group of microorganisms. Thus L. salivarius UCC118 administration has a significant but subtle impact on mouse and pig microbiota, by a mechanism that seems at least partially bacteriocin-dependent.
doi:10.1371/journal.pone.0031113
PMCID: PMC3281923  PMID: 22363561
17.  Effect of Mycobacterium bovis BCG vaccination upon Mycobacterium lepraemurium infection. 
Infection and Immunity  1980;28(3):860-866.
Mice were infected with 10(8) Mycobacterium lepraemurium in the footpad (unsuppressed mice), and some of these animals were concurrently given 10(9) heat-killed M. lepraemurium intravenously (suppressed mice). These groups of mice were preimmunized with 10(7) viable organisms of Mycobacterium bovis BCG by several routes. BCG inhibited the proliferation of M. lepraemurium in the unsuppressed mice, but not in the suppressed mice. In effect, the intravenous administration of heat-killed M. lepraemurium suppressed the immunity to M. lepraemurium that BCG vaccination had engendered. BCG did not protect normal mice against intravenous infection with M. lepraemurium. It appears that normal mice against intravenous infection with M. lepraemurium. It appears that the inhibitory effect of BCG vaccination upon M. lepraemurium infection is due to cross-reactive immunity rather than to nonspecific immunity or immunopotentiation. Thus, the route of BCG vaccination was immaterial, and vaccination 12 weeks before M. lepraemurium infection was as beneficial as vaccination 4 weeks before infection. Moreover, spleen cells from M. lepraemurium-immunized mice conferred adoptive immunity to BCG. The implications of this study for the use of BCG as a prophylactic and therapeutic agent in human leprosy are discussed.
PMCID: PMC551030  PMID: 6995324
18.  Prevention of indigenous infection of mice with Escherichia coli by nonspecific immunostimulation. 
We have previously reported that the lethal toxicity of 5-fluorouracil (5-FU) in specific-pathogen-free mice is due to an intestinal infection with indigenous Escherichia coli induced by the drug (K. Nomoto, T. Yokokura, Y. Yoshikai, M. Mitsuyama, and K. Nomoto, Can J. Microbiol. 37:244-247, 1991). In the present study we demonstrate that nonspecific immunostimulation is effective in the protection of mice from the lethal indigenous infection induced by 5-FU. Intravenous or subcutaneous injection of a preparation of heat-killed Lactobacillus casei YIT 9018, a potent nonspecific immunostimulant, into BALB/c mice reduced the lethal toxicity of 5-FU at doses ranging from 338 to 800 mg/kg of body weight if YIT 9018 was injected 7 to 40 days before administration of 5-FU. Systemic infection with E. coli developed in all of the 5-FU-treated control mice 7 days or more after administration of 5-FU in large doses and was accompanied by overgrowth of the bacteria in the intestinal tract. Pretreatment of mice with YIT 9018 resulted in a decreased occurrence of systemic infection with E. coli to levels of 0 to 20% and no significant changes in the population levels of E. coli in the intestinal tract during the 14 days after administration of 5-FU. The levels of leukopenia in the spleen and peripheral blood were lower, and recovery of granulocyte-macrophage precursor cells in the spleen and femur began earlier in the treated animals than in the 5-FU-treated controls. Intravenous transfusion of syngeneic normal bone marrow cells or spleen cells into the mice at an early period after administration of 5-FU diminished markedly the occurrence of the lethal indigenous infection, suggestion that an earlier recovery from chemotherapy-induced myelosuppression is important in the mechanisms of protection of the host from the infection.
PMCID: PMC188442  PMID: 1605602
19.  Suicin 3908, a New Lantibiotic Produced by a Strain of Streptococcus suis Serotype 2 Isolated from a Healthy Carrier Pig 
PLoS ONE  2015;10(2):e0117245.
While Streptococcus suis serotype 2 is known to cause severe infections in pigs, it can also be isolated from the tonsils of healthy animals that do not develop infections. We hypothesized that S. suis strains in healthy carrier pigs may have the ability to produce bacteriocins, which may contribute to preventing infections by pathogenic S. suis strains. Two of ten S. suis serotype 2 strains isolated from healthy carrier pigs exhibited antibacterial activity against pathogenic S. suis isolates. The bacteriocin produced by S. suis 3908 was purified to homogeneity using a three-step procedure: ammonium sulfate precipitation, cationic exchange HPLC, and reversed-phase HPLC. The bacteriocin, called suicin 3908, had a low molecular mass; was resistant to heat, pH, and protease treatments; and possessed membrane permeabilization activity. Additive effects were obtained when suicin 3908 was used in combination with penicillin G or amoxicillin. The amino acid sequence of suicin 3908 suggested that it is lantibiotic-related and made it possible to identify a bacteriocin locus in the genome of S. suis D12. The putative gene cluster involved in suicin production by S. suis 3908 was amplified by PCR, and the sequence analysis revealed the presence of nine open reading frames (ORFs), including the structural gene and those required for the modification of amino acids, export, regulation, and immunity. Suicin 3908, which is encoded by the suiA gene, exhibited approximately 50% identity with bovicin HJ50 (Streptococcus bovis), thermophilin 1277 (Streptococcus thermophilus), and macedovicin (Streptococcus macedonicus). Given that S. suis 3908 cannot cause infections in animal models, that it is susceptible to conventional antibiotics, and that it produces a bacteriocin with antibacterial activity against all pathogenic S. suis strains tested, it could potentially be used to prevent infections and to reduce antibiotic use by the swine industry.
doi:10.1371/journal.pone.0117245
PMCID: PMC4320106  PMID: 25659110
20.  An Antibiotic-Responsive Mouse Model of Fulminant Ulcerative Colitis  
PLoS Medicine  2008;5(3):e41.
Background
The constellation of human inflammatory bowel disease (IBD) includes ulcerative colitis and Crohn's disease, which both display a wide spectrum in the severity of pathology. One theory is that multiple genetic hits to the host immune system may contribute to the susceptibility and severity of IBD. However, experimental proof of this concept is still lacking. Several genetic mouse models that each recapitulate some aspects of human IBD have utilized a single gene defect to induce colitis. However, none have produced pathology clearly distinguishable as either ulcerative colitis or Crohn's disease, in part because none of them reproduce the most severe forms of disease that are observed in human patients. This lack of severe IBD models has posed a challenge for research into pathogenic mechanisms and development of new treatments. We hypothesized that multiple genetic hits to the regulatory machinery that normally inhibits immune activation in the intestine would generate more severe, reproducible pathology that would mimic either ulcerative colitis or Crohn's disease.
Methods and Findings
We generated a novel mouse line (dnKO) that possessed defects in both TGFβRII and IL-10R2 signaling. These mice rapidly and reproducibly developed a disease resembling fulminant human ulcerative colitis that was quite distinct from the much longer and more variable course of pathology observed previously in mice possessing only single defects. Pathogenesis was driven by uncontrolled production of proinflammatory cytokines resulting in large part from T cell activation. The disease process could be significantly ameliorated by administration of antibodies against IFNγ and TNFα and was completely inhibited by a combination of broad-spectrum antibiotics.
Conclusions
Here, we develop to our knowledge the first mouse model of fulminant ulcerative colitis by combining multiple genetic hits in immune regulation and demonstrate that the resulting disease is sensitive to both anticytokine therapy and broad-spectrum antibiotics. These findings indicated the IL-10 and TGFβ pathways synergize to inhibit microbially induced production of proinflammatory cytokines, including IFNγ and TNFα, which are known to play a role in the pathogenesis of human ulcerative colitis. Our findings also provide evidence that broad-spectrum antibiotics may have an application in the treatment of patients with ulcerative colitis. This model system will be useful in the future to explore the microbial factors that induce immune activation and characterize how these interactions produce disease.
Paul Allen and colleagues describe the development of a mouse model of fulminant ulcerative colitis with multiple genetic hits in immune regulation which can be moderated by anti-cytokine therapy and broad-spectrum antibiotics.
Editors' Summary
Background.
Inflammatory bowel disease (IBD), a group of disorders characterized by inflammation (swelling) of the digestive tract (the tube that runs from the mouth to the anus), affects about 1.4 million people in the US. There are two main types of IBD. In Crohn's disease, which can affect any area of the digestive tract but most commonly involves the lower part of the small intestine (small bowel), all the layers of the intestine become inflamed. In ulcerative colitis, which primarily affects the colon (large bowel) and the rectum (the part of the bowel closest to the anus), only the lining of the bowel becomes inflamed, the cells in this lining die, and sores or ulcers form. Both types of IBD most commonly develop between the ages of 15 and 35 years, often run in families, and carry an increased risk of cancer. Symptoms—usually diarrhea and abdominal cramps—can be mild or severe and the disorder can develop slowly or suddenly. There is no medical cure for IBD, but drugs that modulate the immune system (for example, corticosteroids) can help some people. Some people benefit from treatment with drugs that specifically inhibit “proinflammatory cytokines,” proteins made by the immune system that stimulate inflammation (for example, TNFα and INFγ). When medical therapy fails, surgery to remove the affected part of the bowel may be necessary.
Why Was This Study Done?
Exactly what causes IBD is not clear, but people with IBD seem to have an overactive immune system. The immune system normally protects the body from harmful substances but in IBD it mistakenly recognizes the food substances and “good” bacteria that are normally present in the human gut as foreign and hence reacts against them. As a result, immune system cells accumulate in the lining of the bowel and cause inflammation. Several different pathways usually prevent inappropriate immune activation, so could IBD be caused by alterations in one or several of these immune regulatory pathways? In previous studies, mice with a defect in just one pathway have developed mild intestinal abnormalities but not the problems seen in the most severe forms of IBD. In this study, therefore, the researchers have generated and characterized a new mouse line with defects in two immune regulatory pathways to see whether this might be a better animal model of human IBD.
What Did the Researchers Do and Find?
To make their new mouse line, the researchers mated mice that had a defective TGFβ signaling pathway in their T lymphocytes with mice that had a defective IL-10 signaling pathway. Both these pathways are anti-inflammatory, and mice with defects in either pathway develop mild and variable inflammation of the colon (colitis) by age 3–4 months. By contrast, the doubly defective mice (dnKO mice) failed to thrive, lost weight, and died by 4–6 weeks of age. The colons of 4- to 5-week old dnKO mice were inflamed and ulcerated (some changes were visible in 3-week-old mice) and contained many immune system cells. Mice with a single defective signaling pathway had no gut abnormalities at this age. The dnKO mice, just like people with IBD, had higher than normal blood levels of IFNγ, TNFα, and other proinflammatory cytokines; these raised levels were the result of abnormal lymphocyte activation. Treatment of the dnKO mice with a combination of agents that neutralize IFNγ and TNFα (anti-cytokine therapy) greatly reduced the colitis seen in these mice; neutralization of IFNγ alone had some beneficial effects, but neutralization of TNFα alone had no effect. Finally, early treatment of the dnKO mice with broad-spectrum antibiotics completely inhibited colitis.
What Do These Findings Mean?
These findings suggest that dnKO mice are a good model for fulminant (severe and rapidly progressing) ulcerative colitis and support the idea that IBD involves multiple genetic defects in immune regulation. They also indicate that the IL-10 and the TGFβ signaling pathways normally cooperate to inhibit the inappropriate immune responses to intestinal bacteria seen in IBD. This new mouse model should help researchers unravel what goes wrong in IBD and should also help them develop new treatments for ulcerative colitis. More immediately, these findings suggest that combined anti-cytokine therapy may be a better treatment for ulcerative colitis than single therapy. In addition, they suggest that clinical studies should be started to test whether broad-spectrum antibiotics can ameliorate ulcerative colitis in people.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050041.
The Medline Plus Encyclopedia has pages on Crohn's disease and on ulcerative colitis (in English and Spanish)
Information is available from the UK National Health Service Direct Health Encyclopedia about Crohn's disease and ulcerative colitis
The US National Institute of Diabetes and Digestive and Kidney Diseases provides information on Crohn's disease and ulcerative colitis
Information and support for patients with inflammatory bowel disease and their caregivers is provided by the Crohn's and Colitis Foundation of America and by the UK National Association for Colitis and Crohn's Disease
doi:10.1371/journal.pmed.0050041
PMCID: PMC2270287  PMID: 18318596
21.  Bacteriocinogeny in experimental pigs treated with indomethacin and Escherichia coli Nissle 
AIM: To evaluate bacteriocinogeny in short-term high-dose indomethacin administration with or without probiotic Escherichia coli Nissle 1917 (EcN) in experimental pigs.
METHODS: Twenty-four pigs entered the study: Group A (controls), Group B (probiotics alone), Group C (indomethacin alone) and Group D (probiotics and indomethacin). EcN (3.5 × 1010 bacteria/d for 14 d) and/or indomethacin (15 mg/kg per day for 10 d) were administrated orally. Anal smears before and smears from the small and large intestine were taken from all animals. Bacteriocin production was determined with 6 different indicator strains; all strains were polymerase chain reaction tested for the presence of 29 individual bacteriocin-encoding determinants.
RESULTS: The general microbiota profile was rather uniform in all animals but there was a broad diversity in coliform bacteria (parallel genotypes A, B1, B2 and D found). In total, 637 bacterial strains were tested, mostly Escherichia coli (E. coli). There was a higher incidence of non-E. coli strains among samples taken from the jejunum and ileum compared to that of the colon and rectum indicating predominance of E. coli strains in the large intestine. Bacteriocinogeny was found in 24/77 (31%) before and in 155/560 (28%) isolated bacteria at the end of the study. Altogether, 13 individual bacteriocin types (out of 29 tested) were identified among investigated strains. Incidence of four E. coli genotypes was equally distributed in all groups of E. coli strains, with majority of genotype A (ranging from 81% to 88%). The following types of bacteriocins were most commonly revealed: colicins Ia/Ib (44%), microcin V (18%), colicin E1 (16%) and microcin H47 (6%). There was a difference in bacteriocinogeny between control group A (52/149, 35%) and groups with treatment at the end of the study: B: 31/122 (25%, P = 0.120); C: 43/155 (28%, P = 0.222); D: 29/134 (22%, P = 0.020). There was a significantly lower prevalence of colicin Ib, microcins H47 and V (probiotics group, P < 0.001), colicin E1 and microcin H47 (indomethacin group, P < 0.001) and microcins H47 and V (probiotics and indomethacin group, P = 0.025) compared to controls. Escherichia fergusonii (E. fergusonii) was identified in 6 animals (6/11 isolates from the rectum). One strain was non-colicinogenic, while all other strains of E. fergusonii solely produced colicin E1. All animals started and remained methanogenic despite the fact that EcN is a substantial hydrogen producer. There was an increase in breath methane (after the treatment) in 5/6 pigs from the indomethacin group (C).
CONCLUSION: EcN did not exert long-term liveability in the porcine intestine. All experimental pigs remained methanogenic. Indomethacin and EcN administered together might produce the worst impact on bacteriocinogeny.
doi:10.3748/wjg.v17.i5.609
PMCID: PMC3040332  PMID: 21350709
Bacteriocinogeny; Escherichia coli Nissle 1917; Experimental pigs; Indomethacin
22.  Impact of LY146032 on Streptococcus (Enterococcus) faecalis translocation in mice. 
The susceptibility of Swiss White mice to colonization with Streptococcus (Enterococcus) faecalis was greatly increased when the animals were given 5 mg of streptomycin sulfate per ml in their drinking water. One week after initiation of streptomycin treatment, the mice were challenged orogastrically with graded doses of streptomycin-resistant S. faecalis. The number of S. faecalis cells required to implant the intestinal tract of 50% of untreated mice was 2.9 X 10(9), but was only 4.8 X 10(3) for streptomycin-treated animals. When both groups of mice were challenged orogastrically with 4.6 X 10(6) viable S. faecalis cells, the cecum and small intestine of 100% of the streptomycin-treated animals, but only 10% of the untreated animals, were colonized with the organism. Similarly, translocation of S. faecalis to extraintestinal sites occurred in a majority of streptomycin-treated mice, but in only a small number of untreated mice. Subcutaneous administration of the experimental antibiotic LY146032 (Eli Lilly & Co., Indianapolis, Ind.) to streptomycin-treated mice concomitant with orogastric challenge with 5.5 X 10(5) viable S. faecalis cells resulted in a significant decrease in the incidence of intestinal colonization by the organism, a significant reduction in S. faecalis populations, and the absence of the organism in the liver, spleen, and heart. However, once intestinal colonization had occurred and extraintestinal infections were established, LY146032 did not significantly reduce S. faecalis populations or ameliorate the infections. We conclude that LY146032 effectively prevents translocation of S. faecalis from the intestinal tract of mice but does not resolve established extraintestinal infections.
PMCID: PMC172171  PMID: 2835001
23.  Bacteriocins as Factors in the In Vitro Interaction Between Oral Streptococci in Plaque 
Infection and Immunity  1977;16(3):773-780.
The effect of bacteriocins on the composition of dental plaque flora was studied in vitro with bacterial plaque formed by oral streptococci on glass rods suspended in broth medium. Cell-free preparations containing mutacin SW31, a bacteriocin produced by Streptococcus mutans, killed sensitive cells present in the plaque selectively, but did not affect resistant cells. Similar preparations from a non-bacteriocinogenic mutant exerted only a slight effect. Mixed growth of bacteriocin-producing S. mutans SW31 with the sensitive S. sanguis Ny101 resulted in a nearly single-strain plaque of the former. Mutacin could be detected in the plaque substance as well as in the surrounding medium. A non-bacteriocinogenic mutant, which was shown not to be altered in functions affecting growth in plaque, allowed substantial growth of S. sanguis Ny101. Sequential inoculation of the bacteriocinogenic plaque former S. sanguis P3A3 and the sensitive S. mutans OMZ61 showed that the cells of the latter are killed rapidly in established plaques when inoculated with the bacteriocinogenic strain. A trypsin-sensitive antagonistic substance could be detected in the plaque, but not in the surrounding medium. The results indicate that bacteriocins can be active in plaque in vitro and suggest that bacteriocins could play a role in determining the composition of plaque in vivo.
Images
PMCID: PMC421029  PMID: 892898
24.  Comparative Functional Genomics and the Bovine Macrophage Response to Strains of the Mycobacterium Genus 
Mycobacterial infections are major causes of morbidity and mortality in cattle and are also potential zoonotic agents with implications for human health. Despite the implementation of comprehensive animal surveillance programs, many mycobacterial diseases have remained recalcitrant to eradication in several industrialized countries. Two major mycobacterial pathogens of cattle are Mycobacterium bovis and Mycobacterium avium subspecies paratuberculosis (MAP), the causative agents of bovine tuberculosis (BTB) and Johne’s disease (JD), respectively. BTB is a chronic, granulomatous disease of the respiratory tract that is spread via aerosol transmission, while JD is a chronic granulomatous disease of the intestines that is transmitted via the fecal-oral route. Although these diseases exhibit differential tissue tropism and distinct complex etiologies, both M. bovis and MAP infect, reside, and replicate in host macrophages – the key host innate immune cell that encounters mycobacterial pathogens after initial exposure and mediates the subsequent immune response. The persistence of M. bovis and MAP in macrophages relies on a diverse series of immunomodulatory mechanisms, including the inhibition of phagosome maturation and apoptosis, generation of cytokine-induced necrosis enabling dissemination of infection through the host, local pathology, and ultimately shedding of the pathogen. Here, we review the bovine macrophage response to infection with M. bovis and MAP. In particular, we describe how recent advances in functional genomics are shedding light on the host macrophage–pathogen interactions that underlie different mycobacterial diseases. To illustrate this, we present new analyses of previously published bovine macrophage transcriptomics data following in vitro infection with virulent M. bovis, the attenuated vaccine strain M. bovis BCG, and MAP, and discuss our findings with respect to the differing etiologies of BTB and JD.
doi:10.3389/fimmu.2014.00536
PMCID: PMC4220711  PMID: 25414700
cattle; BCG; gene expression; Johne’s disease; macrophage; Mycobacterium avium subspecies paratuberculosis; Mycobacterium bovis; tuberculosis
25.  Mycobacterial Antigens Exacerbate Disease Manifestations in Mycobacterium tuberculosis-Infected Mice  
Infection and Immunity  2002;70(4):2100-2107.
To control tuberculosis worldwide, the burden of adult pulmonary disease must be reduced. Although widely used, Mycobacterium bovis BCG vaccination given at birth does not protect against adult pulmonary disease. Therefore, postexposure vaccination of adults with mycobacterial antigens is being considered. We examined the effect of various mycobacterial antigens on mice with prior M. tuberculosis infection. Subcutaneous administration of live or heat-treated BCG with or without lipid adjuvants to infected mice induced increased antigen-specific T-cell proliferation but did not reduce the bacterial load in the lungs and caused larger lung granulomas. Similarly, additional mycobacterial antigen delivered directly to the lungs by aerosol infection with viable M. tuberculosis mixed with heat-killed Mycobacterium tuberculosis (1:1) also did not reduce the bacillary load but caused increased expression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), which was associated with larger granulomas in the lungs. When M. tuberculosis-infected mice were treated with recombinant BCG that secreted cytokines shown to reduce disease in a preinfection vaccine model, the BCG secreting TNF-α, and to a lesser extent, IL-2 and gamma interferon (IFN-γ), caused a significant increase in granuloma size in the lungs. Moreover, treatment of M. tuberculosis-infected mice with recombinant murine TNF-α resulted in increased inflammation in the lungs and accelerated mortality without affecting the bacillary load. Taken together, these studies suggest that administration of mycobacterial antigens to mice with prior M. tuberculosis infection leads to immune activation that may exacerbate lung pathology via TNF-α-induced inflammation without reducing the bacillary load.
doi:10.1128/IAI.70.4.2100-2107.2002
PMCID: PMC127838  PMID: 11895976

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