Development of bronchus-associated lymphoid tissue has been suggested to enhance local antiviral immune responses; however, ectopic lymph node formation often corresponds to chronic inflammatory diseases. These studies investigated the role of ectopic pulmonary lymph nodes upon respiratory syncytial virus (RSV) infection using CCR7-deficient mice, which develop bronchus-associated lymphoid tissue early in life. CCR7−/− mice exhibited impaired secondary lymph node formation, enhanced effector T cell responses and pathogenic mucus production in the lung after RSV infection. IL-17 production from CD4 T cells in CCR7−/− mice was most remarkably enhanced. Wild-type animals reconstituted with CCR7−/− bone marrow recapitulated the pathogenic lung phenotype in CCR7−/− mice, whereas CCR7−/− animals reconstituted with wild-type bone marrow had normal lymph node development, diminished IL-17 production and reduced lung pathology. Mixed bone marrow chimeras revealed an alteration of immune responses only in CCR7−/− T cells, suggesting that impaired trafficking promotes local effector cell generation. Lymphotoxin-α–deficient mice infected with RSV were used to further examine locally induced immune responses and demonstrated increased mucus production and amplified cytokine responses in the lung, especially IL-17. Neutralization of IL-17 in CCR7−/− or in lymphotoxin-α–deficient animals specifically inhibited mucus hypersecretion and reduced IL-13. Thus, immune cell trafficking to secondary lymph nodes is necessary for appropriate cytokine responses to RSV as well as modulation of the local environment.
Recent work has demonstrated the importance of macroautophagy in dendritic cell (DC) maturation and innate cytokine production upon viral infection through delivery of cytoplasmic viral components to intracellular toll-like receptors. To study the functional consequences of impaired autophagosome formation during a Respiratory Syncytial Virus (RSV) infection, mice harboring significant autophagy defects due to Beclin-1 haploinsufficiency (Beclin-1+/−) were used. Upon RSV infection in vivo, lungs of Beclin-1+/− mice showed increased Th2 cytokine production, mucus secretion, and lung infiltration of eosinophils and inflammatory DCs. While isolated airway epithelial cells from Beclin-1+/− mice demonstrated little change compared to wildtype, Beclin-1+/− pulmonary and bone marrow-derived DCs (BMDCs) showed decreased expression of MHC-II and innate cytokine production upon RSV infection. Further examination indicated that Beclin-1+/− DC stimulated less IFNγ and IL-17 production by co-cultured CD4+ T cells and increased Th2 cytokine production in comparison to wild-type controls. Finally, adoptive transfer of RSV-infected Beclin-1+/− DCs into the airways of wild-type mice produced severe lung pathology and increased Th2 cytokine production upon subsequent RSV challenge compared to wild-type DC transfer controls. These results indicate a critical role of autophagy in dendritic cells during pulmonary viral infection, facilitating appropriate antiviral adaptive immune responses.
This study identifies the IL-25 receptor, IL-17RB, is an important mediator of both innate and adaptive pulmonary type 2 immune responses. Allergen exposure upregulated IL-25 and induced type 2 cytokine production in a novel granulocytic population, termed Type 2 Myeloid (T2M) cells. Il17rb−/− mice exhibited reduced lung pathology following chronic allergen exposure and decreased cytokine production in T2M cells and CD4+ T-lymphocytes. Airway instillation of IL-25 induced IL-4 and IL-13 production exclusively in T2M cells demonstrating their importance in generating T cell-independent inflammation. The adoptive transfer of T2M cells reconstituted IL-25-mediated responses in Il17rb−/− mice. High dose dexamethasone treatment did not reduce the IL-25-induced T2M pulmonary response. Finally, a similar IL-4/IL-13 producing granulocytic population was identified in peripheral blood of asthmatics. These data establish IL-25/IL-17RB as targets for innate and adaptive immune responses in chronic allergic airways disease, and identify T2M cells as a novel steroid-resistant cell population.
The regulation of innate immune responses during viral infection is a crucial step to promote anti-viralreactions. Recent studies have drawn attention to a strong relationship of pathogen associated molecular patterns (PAMP) recognition with autophagy for activation of APC function. Our initial observations indicated that autophagosomes formed in response to RSV infection of DC. To further investigate whether RSV-induced DC activation and innate cytokine production was associated with autophagy, we utilized several methods to block autophagosome formation. Using 3-MA,siRNA inhibition of LC3,or Beclin +/- mouse derived DC,studies establisheda relationship between RSV-induced autophagy and enhanced type I IFN, TNF, IL-6, and IL-12p40expression. Moreover, autophagosome formation induced by starvation also promoted innate cytokine expression in DC. The induction of starvation-induced autophagy in combination with RSV infection synergistically enhanced DC cytokine expressionthat was blocked by an autophagy inhibitor. The latter synergistic responses were differentially altered in DC from MyD88-/- and TRIF-/-mice supporting the concept of autophagy-mediated TLR signaling. In addition, blockade of autophagy in RSV-infected DC inhibited the maturation of DCs as assessed by MHC Class II and co-stimulatory molecule expression. Subsequently, we demonstrated that inhibition of autophagy in DCsused to stimulateprimary ovalbumin-induced and secondary RSV-infected responses significantly attenuatedcytokine production by CD4+ T cells. Thus, these studies have outlined that autophagy in DC afterRSV infection isa crucial mechanism for driving innate cytokine productionleading to alteredacquired immune responses.
Activation of the canonical Notch pathways has been implicated in Th cell differentiation, but the role of specific Notch ligands in Th2 mediated allergic airway responses has not been completely elucidated. In this study, we show that delta-like 4 (Dll4) was up-regulated on dendritic cells in response to cockroach allergen. Blocking Dll4 in vivo during either the primary or secondary response enhanced allergen-induced pathogenic consequences including airway hyperresponsiveness (AHR) and mucus production via increased Th2 cytokines. In vitro assays demonstrated that Dll4 regulates IL-2 in T cells from established Th2 responses as well as during primary stimulation. Interestingly, Dll4 blockade during the primary, but not the secondary response, increased IL-2 levels in lung and lymph node of allergic mice. The in vivo neutralization of Dll4 was associated with increased expansion and decreased apoptosis during the primary allergen sensitization. Moreover, Dll4-mediated Notch activation of T cells during primary stimulation in vitro increased apoptosis during the contraction/resting phase of the response, which could be rescued by exogenous IL-2. Consistent with the role for Dll4-mediated IL-2 regulation in overall T cell function, the frequency of IL-4 producing cells were also significantly altered by Dll4 both in vivo and in vitro. These data demonstrate a regulatory role of Dll4 on both initial Th2 differentiation as well as on Th2 cytokine production in established allergic responses.
Viruses utilize Tyro3, Axl, and Mertk (TAM) receptor tyrosine kinases to infect and modulate the immune properties of various cell types leading us to investigate whether TAM receptor activation impacted primary viral infection and viral exacerbation of asthma in experimental models. In these lung-specific models, we observed that Axl was the most abundantly induced TAM receptor protein. During primary respiratory syncytial virus (RSV) infection, anti-Axl mAb treatment significantly increased the number of IFN-γ-producing T cells and NK cells, and significantly suppressed RSV replication and whole lung levels of IL-4 and IL-13. Intrapulmonary H1N1 infection induced lethal pulmonary inflammation but anti-Axl mAb treatment of infected mice significantly increased the number of IFN-β-producing macrophages and dendritic cells, and significantly suppressed neutrophil infiltration. Consequently, the lethal effect of H1N1 infection in this model was significantly reduced in the mAb-treated group compared with the IgG control-treated group. Targeting Axl also inhibited airway hyperresponsiveness, IL-4 and IL-13 production, and goblet cell metaplasia in an Aspergillus fumigatus-induced asthma model. Finally, infection of mice with RSV during fungal asthma significantly exacerbated airway inflammation, goblet cell metaplasia, and airway remodeling but all of these features in this viral exacerbation model were ameliorated by anti-Axl mAb treatment. Together, these results demonstrate that Axl modulates the pulmonary immune response during viral and/or allergic pathology, and also suggest that targeting this TAM receptor might provide a novel therapeutic approach in these infectious diseases.
Axl; Mertk; Anti-monoclonal Axl antibody; RSV; Influenza virus; Aspergillus fumigatus; Asthma; Allergic inflammation
Innate immunity is required for effective control of poxvirus infections, but cellular receptors that initiate the host response to these DNA viruses remain poorly defined. Given this information and the fact that functions of TLRs in immunity to DNA viruses remain controversial, we investigated effects of TLR3 on pathogenesis of vaccinia virus, a prototype poxvirus. We used a recombinant strain Western Reserve vaccinia virus that expresses firefly luciferase to infect wild-type C57BL/6 and TLR3−/− mice through intranasal inoculation. Bioluminescence imaging showed that TLR3−/− mice had substantially lower viral replication in the respiratory tract and diminished dissemination of virus to abdominal organs. Mice lacking TLR3 had reduced disease morbidity, as measured by decreased weight loss and hypothermia after infection. Importantly, TLR3−/− mice also had improved survival relative to wild-type mice. Infected TLR3−/− mice had significantly reduced lung inflammation and recruitment of leukocytes to the lung. Mice lacking TLR3 also had lower levels of inflammatory cytokines, including IL-6, MCP-1, and TNF-α in serum and/or bronchoalveolar lavage fluid, but levels of IFN-β did not differ between genotypes of mice. To our knowledge, our findings show for the first time that interactions between TLR3 and vaccinia increase viral replication and contribute to detrimental effects of the host immune response to poxviruses.
Respiratory syncytial virus (RSV) infection can result in severe disease partially due to its ability to interfere with the initiation of Th1 responses targeting the production of type I interferons (IFN) and promoting a Th2 immune environment. Epigenetic modulation of gene transcription has been shown to be important in regulating inflammatory pathways. RSV-infected bone marrow-derived DCs (BMDCs) upregulated expression of Kdm5b/Jarid1b H3K4 demethylase. Kdm5b-specific siRNA inhibition in BMDC led to a 10-fold increase in IFN-β as well as increases in IL-6 and TNF-α compared to control-transfected cells. The generation of Kdm5bfl/fl-CD11c-Cre+ mice recapitulated the latter results during in vitro DC activation showing innate cytokine modulation. In vivo, infection of Kdm5bfl/fl-CD11c-Cre+ mice with RSV resulted in higher production of IFN-γ and reduced IL-4 and IL-5 compared to littermate controls, with significantly decreased inflammation, IL-13, and mucus production in the lungs. Sensitization with RSV-infected DCs into the airways of naïve mice led to an exacerbated response when mice were challenged with live RSV infection. When Kdm5b was blocked in DCs with siRNA or DCs from Kdm5bfl/fl-CD11c-CRE mice were used, the exacerbated response was abrogated. Importantly, human monocyte-derived DCs treated with a chemical inhibitor for KDM5B resulted in increased innate cytokine levels as well as elicited decreased Th2 cytokines when co-cultured with RSV reactivated CD4+ T cells. These results suggest that KDM5B acts to repress type I IFN and other innate cytokines to promote an altered immune response following RSV infection that contributes to development of chronic disease.
Respiratory syncytial virus (RSV) is a significant public health concern. Nearly all children are infected by two years of age, and severe infection often results in hospitalization. There is no vaccine for RSV, and previous attempts have resulted in increased disease severity in immunized children once they were exposed to the virus. Therefore, a better understanding of how RSV directs the immune response is needed. In this study, we found that the protein KDM5B regulates an epigenetic mechanism that directs the immune response to RSV. KDM5B suppressed the activation of key antiviral signals in dendritic cells, and inhibition of KDM5B led to gene activation and increased antiviral function. This correlated with decreased pathology in the lungs. Therefore, our data suggest that new attempts at designing a vaccine should consider the effects of vaccination on dendritic cells, and should consider strategies that will increase antiviral signals from dendritic cells.
The activation and differentiation of T cells are dependent upon numerous initiating events that are influenced by the immune environment, nature of the antigen, as well as the activation state of APCs. In the present studies we have investigated the role of a specific notch ligand, delta-like 4 (Dll4). In particular, our data have indicated that Dll4 is inducible by pathogen-associated signals through TLR activation on DC but not early response inflammatory cytokines, IL-1 and IL-18 that also activate cells via MyD88 adapter pathway. Our observations from in vitro cultures with ovalbumin specific TCR transgenic cells (DO11.10) confirmed earlier reports demonstrating that Dll4 inhibits Th2 cytokine production. Furthermore, Dll4 enhances the generation of IL-17 producing T cells in the presence of additional skewing cytokines, IL-6 and TGFβ. In the absence of notch signals IL17 production was significantly reduced even under specific skewing conditions. These studies further demonstrate that Dll4 upregulates RORγt expression in T cells and that both RORγt and IL17 gene promoters are direct transcriptional notch targets that augment the differentiation of Th17 cell populations. Thus, facilitation of efficient T cell differentiation may depend upon the activation of T cells via specific notch ligand stimulation.
The severity of allergic asthma is dependent, in part, on the intensity of peribronchial inflammation. P-selectin is known to play a role in the development of allergen-induced peribronchial inflammation and airway hyperreactivity. Selective inhibitors of P-selectin-mediated leukocyte endothelial-cell interactions may therefore attenuate the inflammatory processes associated with allergic airway disease. Novel P-selectin inhibitors were created using a polyvalent polymer nanoparticle capable of displaying multiple synthetic, low molecular weight ligands. By assembling a particle that presents an array of groups, which as monomers interact with only low affinity, we created a construct that binds extremely efficiently to P-selectin. The ligands acted as mimetics of the key binding elements responsible for the high-avidity adhesion of P-selectin to the physiologic ligand, PSGL-1. The inhibitors were initially evaluated using an in vitro shear assay system in which interactions between circulating cells and P-selectin-coated capillary tubes were measured. The nanoparticles were shown to preferentially bind to selectins expressed on activated endothelial cells. We subsequently demonstrated that nanoparticles displaying P-selectin blocking arrays were functionally active in vivo, significantly reducing allergen-induced airway hyperreactivity and peribronchial eosinophilic inflammation in a murine model of asthma.
selectin inhibitor; asthma; eosinophil; lung
Respiratory viral infection, including respiratory syncytial virus (RSV) and rhinovirus, has been linked to respiratory disease in pediatric patients, including severe acute bronchiolitis and asthma exacerbation.
The study examined the role of the epithelial-derived cytokine thymic stromal lymphopoietin (TSLP) in the response to RSV infection.
Infection of human airway epithelial cells was used to examine TSLP induction after RSV infection. Air–liquid interface cultures from healthy children and children with asthma were also tested for TSLP production after infection. Finally, a mouse model was used to directly test the role of TSLP signaling in the response to RSV infection.
Infection of airway epithelial cells with RSV led to the production of TSLP via activation of an innate signaling pathway that involved retinoic acid induced gene I, interferon promoter-stimulating factor 1, and nuclear factor-κB. Consistent with this observation, airway epithelial cells from asthmatic children a produced significantly greater levels of TSLP after RSV infection than cells from healthy children. In mouse models, RSV-induced TSLP expression was found to be critical for the development of immunopathology.
These findings suggest that RSV can use an innate antiviral signaling pathway to drive a potentially nonproductive immune response and has important implications for the role of TSLP in viral immune responses in general.
TSLP; RSV; asthma; epithelium; TH2
Viral infections are the most frequent cause of asthma exacerbations and are linked to increased airway reactivity (AR) and inflammation. Mice infected with respiratory syncytial virus (RSV) during ovalbumin (OVA)-induced allergic airway inflammation (OVA/RSV) had increased AR compared to OVA or RSV mice alone. Further, IL-17A was only increased in OVA/RSV mice.
To determine if IL-17A increases AR and inflammation in the OVA/RSV model.
Wild-type BALB/c and IL-17A KO mice underwent mock, RSV, OVA, or OVA/RSV protocols. Lungs, bronchoalveolar lavage (BAL) fluid, and/or mediastinal lymph nodes (MLNs) were harvested post infection. Cytokine expression was determined by flow cytometry and ELISA in the lungs or BAL fluid. MLNs were restimulated with either OVA (323–229) peptide or RSV M2 (127–135) peptide and IL-17A protein expression was analyzed. AR was determined by methacholine challenge.
RSV increased IL-17A protein expression by OVA-specific T cells 6 days post infection. OVA/RSV mice had decreased IFN-α and IFN-β protein expression compared to RSV mice. OVA/RSV mice had increased IL-23 mRNA expression in lung homogenates compared to mock, OVA, or RSV mice. Unexpectedly, IL-17A KO OVA/RSV mice had increased AR compared to WT OVA/RSV mice. Further, IL-17A KO OVA/RSV mice had increased eosinophils, lymphocytes, and IL-13 protein expression in BAL fluid compared to WT OVA/RSV mice.
IL-17A negatively regulated AR and airway inflammation in OVA/RSV mice. This finding is important because IL-17A has been identified as a potential therapeutic target in asthma, and inhibiting IL-17A in the setting of virally induced asthma exacerbations may have adverse consequences.
IL-17A; airway reactivity; CD4+ T cells; allergic inflammation; RSV
Theiler's murine encephalomyelitis virus induces a demyelinating disease (TMEV-IDD) of the central nervous system (CNS) in susceptible mouse strains with accompanying histopathology characterized by mononuclear cell infiltrates. In susceptible strains of mice such as SJL, virus establishes a persistent infection in macrophages, induces a CNS infiltration by macrophages, T cells, and B cells, which results in chronic-progressive paralysis. In the present report the authors have investigated the functional role of CCL2 (monocyte chemotactic protein-1) in the induction and progression of demyelinating disease. Treatment of infected mice at day 0, 14, or 28 with anti-CCL2 resulted in a significant decrease in the clinical disease progression. Further analysis of anti-CCL2–treated mice revealed decreased CNS inflammation and mononuclear cell infiltration with an accompanying change in inflammatory cytokine responses. There was an overall decrease in the absolute numbers of CNS-infiltrating CD4+ T cells, macrophages, and B cells. Finally, anti-CCL2 treatment resulted in decreased viral load in the CNS. These data directly demonstrate a role for CCL2 in the pathogenesis of TMEV-IDD.
cell trafficking; chemokines; demyelinating disease; multiple sclerosis; neuroimmunology; Theiler's virus
The cytosolic RNA helicases melanoma differentiation-associated gene 5 (MdA5) and retinoic acid-inducible gene-I (RIG-I) and their adaptor IFNβ promotor stimulator (IPS-1) have been implicated in the recognition of viral RNA and the production of type I interferon (IFN). Complementing the endosomal Toll-like receptors (TLR), Mda5 and RIG-I provide alternative mechanisms for viral detection in cells with reduced phagocytosis or autophagy. The infection route of Respiratory Syncytial Virus (RSV) - via fusion of virus particles with the cell membrane - points to IPS-1 signaling as the pathway of choice for downstream antiviral responses. In the present study, viral clearance and inflammation resolution were indeed strongly affected by the absence of an initial IPS-1-mediated IFNβ response. Despite the blunted inflammatory response in IPS-1 deficient alveolar epithelial cells, pulmonary macrophages and CD11b+ dendritic cells (DC), lungs of RSV-infected IPS-1 knockout (KO) mice showed augmented recruitment of inflammatory neutrophils, monocytes and DC. Interestingly, pulmonary CD103+ DC could functionally compensate for IPS-1 deficiency with the up-regulation of certain inflammatory cytokines and chemokines, possibly via TLR3 and TLR7 signaling. The increased inflammation and reduced viral clearance in IPS-1 KO mice was accompanied by increased T-cell activation and IFNγ production. Experiments with bone marrow chimeras indicated that RSV-induced lung pathology was most severe when IPS-1 expression was lacking in both immune and non-immune cell populations. Similarly, viral clearance was rescued upon restored IPS-1 signaling in either the non-immune or the immune compartment. These data support a non-redundant function for IPS-1 in controlling RSV-induced inflammation and viral replication.
Survivors of severe sepsis exhibit increased morbidity and mortality in response to secondary infections. Although bacterial secondary infections have been widely studied, there remains a paucity of data concerning viral infections post-sepsis. In an experimental mouse model of severe sepsis (cecal ligation and puncture, CLP) followed by respiratory syncytial virus (RSV) infection, exacerbated immunopathology was observed in the lungs of CLP mice compared to RSV-infected sham surgery mice. This virus-associated immunopathology was evidenced by increased mucus production in the lungs of RSV-infected CLP mice and correlated with increased IL-17 production in the lungs. RSV infected CLP mice exhibited increased levels of Th2 cytokines and reduced IFNγ in the lungs and lymph nodes compared to RSV-infected sham mice. In addition, CD4 T cells from CLP mice produced increased IL-17 in vitro irrespective of the presence of exogenous cytokines or blocking antibodies. This increased IL-17 production correlated wth increased STAT3 transcription factor binding to the IL-17 promoter in CD4 T cells from CLP mice. Further, in vivo neutralization of IL-17 prior to RSV infection led to a significant reduction in virus induced mucus production and Th2 cytokines. Taken together, these data provide evidence that post septic CD4+T cells are primed toward IL-17 production via increased STAT3-mediated gene transcription, which may contribute to the immunopathology of a secondary viral infection.
Inflammation; infection; mucus; cytokines; lymphocytes
Toll-like receptor (TLR) activation has been implicated in acetaminophen (APAP)-induced hepatotoxicity. Herein, we hypothesize that TLR3 activation significantly contributed to APAP-induced liver injury. In fasted wildtype (WT) mice, APAP caused significant cellular necrosis, edema, and inflammation in the liver, and the de novo expression and activation of TLR3 was found to be necessary for APAP-induced liver failure. Specifically, liver tissues from similarly fasted TLR3-deficient (tlr3−/−) mice exhibited significantly less histological and biochemical evidence of injury after APAP challenge. Similar protective effects were observed in WT mice in which TLR3 was targeted through immunoneutralization at 3 h post-APAP challenge. Among three important death ligands (i.e. TNFα, TRAIL, and FASL) known to promote hepatocyte death after APAP challenge, TNFα was the only ligand that was significantly reduced in APAP-challenged tlr3−/− mice compared with APAP-challenged WT controls. In vivo studies demonstrated that TLR3 activation contributed to TNFα production in the liver presumably via F4/80+ and CD11c+ immune cells. In vitro studies indicated that there was cooperation between TNFα and TLR3 in the activation of JNK signaling in isolated and cultured liver epithelial cells (i.e. nMuLi). Moreover, TLR3 activation enhanced the expression of phosphorylated JNK in APAP injured livers. Thus, the current study demonstrates that TLR3 activation contributes to APAP-induced hepatotoxicity.
CD8+ T cells may contribute to vaccines for respiratory syncytial virus (RSV). Compared to CD8+ T cells responding to RSV infection, vaccine-elicited anti-RSV CD8+ T cells are less well defined. We used a peptide vaccine to test the hypothesis that vaccine-elicited RSV-specific CD8+ T cells are protective against RSV pathogenesis. BALB/c mice were treated with a mixture (previously termed TriVax) of an M282-90 peptide representing an immunodominant CD8 epitope, the Toll-like receptor (TLR) agonist poly(I·C), and a costimulatory anti-CD40 antibody. TriVax vaccination induced potent effector anti-RSV CD8+ cytotoxic T lymphocytes (CTL). Mice were challenged with RSV strain A2-line19F, a model of RSV pathogenesis leading to airway mucin expression. Mice were protected against RSV infection and against RSV-induced airway mucin expression and cellular lung inflammation when challenged 6 days after vaccination. Compared to A2-line19F infection alone, TriVax vaccination followed by challenge resulted in effector CD8+ T cells with greater cytokine expression and the more rapid appearance of RSV-specific CD8+ T cells in the lung. When challenged 42 days after TriVax vaccination, memory CD8+ T cells were elicited with RSV-specific tetramer responses equivalent to TriVax-induced effector CD8+ T cells. These memory CD8+ T cells had lower cytokine expression than effector CD8+ T cells, and protection against A2-line19F was partial during the memory phase. We found that vaccine-elicited effector anti-RSV CD8+ T cells protected mice against RSV infection and pathogenesis, and waning protection correlated with reduced CD8+ T cell cytokine expression.
Recent studies link early rhinovirus (RV) infections to later asthma development. We hypothesized that neonatal RV infection leads to an IL-13-driven asthma-like phenotype in mice. BALB/c mice were inoculated with RV1B or sham on day 7 of life. Viral RNA persisted in the neonatal lung up to 7 days after infection. Within this time frame, IFNs-α, -β and -γ peaked 1 day after infection, whereas IFN-λ levels persisted. Next, we examined mice on day 35 of life, 28 days after initial infection. Compared to sham-treated controls, virus-inoculated mice demonstrated airways hyperresponsiveness. Lungs from RV-infected mice showed increases in several immune cell populations, as well as the percentages of CD4-positive T cells expressing IFN-γ and of NKp46/CD335+, TCR-β+ cells expressing IL-13. Periodic acid-Schiff and immunohistochemical staining revealed mucous cell metaplasia and muc5AC expression in RV1B- but not sham-inoculated lungs. Mucous metaplasia was accompanied by induction of gob-5, MUC5AC, MUC5B and IL-13 mRNA. By comparison, adult mice infected with RV1B showed no change in IL-13 expression, mucus production or airways responsiveness 28 days after infection. Intraperitoneal administration of anti-IL13 neutralizing antibody attenuated RV-induced mucous metaplasia and methacholine responses, and IL-4R null mice failed to show RV-induced mucous metaplasia. Finally, neonatal RV increased the inflammatory response to subsequent allergic sensitization and challenge. We conclude that neonatal RV1B infection leads to persistent airways inflammation, mucous metaplasia and hyperresponsiveness which are mediated, at least in part, by IL-13.
asthma; BALB/c; childhood; gob-5; IL-13
Thymic stromal lymphopoietin (TSLP) has been implicated in the development of allergic inflammation by promoting Th2-type responses and has become a potential therapeutic target. Using in vitro T cell differentiation cultures we were able to validate that TSLP played a more critical role in the early development of Th2 immune responses with less significant enhancement of already developed Th2 responses. Adoptive transfer of naive DO11.10 ovalbumin-specific T cells followed by airway exposure to ovalbumin showed an early impairment of Th2 immune response in TSLP−/− mice compared to wild type mice during the development of a Th2 response. In contrast, transfer of already differentiated Th2 cells into TSLP−/− mice did not change lung pathology or Th2 cytokine production upon ovalbumin challenge compared to transfer into wild type mice. An allergen-induced Th2 airway model demonstrated that there was only a difference in gob5 expression (a mucus-associated gene) between wild type and TSLP−/− mice. Furthermore, when allergic animals with established disease were treated with a neutralizing anti-TSLP antibody there was no change in airway hyperreponsiveness (AHR) or Th2 cytokine production compared to the control antibody treated animals, whereas a change in gob5 gene expression was also observed similar to the TSLP−/− mouse studies. In contrast, when animals were treated with anti-TSLP during the initial stages of allergen sensitization there was a significant change in Th2 cytokines during the final allergen challenge. Collectively, these studies suggest that in mice TSLP has an important role during the early development of Th2 immune responses, whereas its role at later stages of allergic disease may not be as critical for maintaining the Th2-driven allergic disease.
IL-13 is a central mediator of airway hyperreactivity and mucus expression, both hallmarks of asthma. IL-13 is found in the sputum of patients with asthma; therefore, IL-13 is an attractive drug target for treating asthma. We have previously shown that IL-13 inhibits Th17 cell production of IL-17A and IL-21 in vitro. Th17 cells are associated with autoimmune diseases, host immune responses, and severe asthma. In this study, we extend our in vitro findings and determine that IL-13 increases IL-10 production from Th17 polarized cells, and that IL-13-induced IL-10 production negatively regulates secretion of IL-17A and IL-21. To determine if IL-13 negatively regulates lung IL-17A expression via an IL-10 dependent mechanism in vivo, we used a model of respiratory syncytial virus (RSV) strain A2 infection in STAT1 KO mice which increases IL-17A and IL-13 lung expression, cytokines not produced during RSV infection in WT mice. To test the hypothesis that IL-13 negatively regulates lung IL-17A expression, we created STAT1/IL-13 double KO (DKO) mice. We found that RSV-infected STAT1/IL-13 DKO mice had significantly greater lung IL-17A expression compared to STAT1 KO mice, and increased IL-17A expression was abrogated by anti-IL-10 antibody treatment. RSV-infected STAT1/IL-13 DKO mice also had increased neutrophil infiltration RSV-infected STAT1 KO mice. Neutralizing IL-10 increased infiltration of inflammatory cells into the lungs of STAT1 KO mice but not STAT1/IL-13 DKO mice. These findings are vital to understanding potential side effects of therapeutics targeting IL-13. Inhibiting IL-13 may decrease IL-10 production and increase IL-17A production, thus potentiating IL-17A-associated diseases.
Schistosome worms have been infecting humans for millennia, but it is only in the last half century that we have begun to understand the complexities of this inter-relationship. As our sophistication about the inner workings of every aspect of the immune system has increased, it has also become obvious that schistosome infections have broad ranging effects on nearly all of the innate and adaptive immune response mechanisms. Selective pressures on both the worms and their hosts, has no doubt led to co-evolution of protective mechanisms, particularly those that favor granuloma formation around schistosome eggs and immune suppression during chronic infection. The immune modulatory effects that chronic schistosome infection and egg deposition elicit have been intensely studied, not only because of their major implications to public health issues, but also due to the emerging evidence that schistosome infection may protect humans from severe allergies and autoimmunity. Mouse models of schistosome infection have been extremely valuable for studying immune modulation and regulation, and in the discovery of novel aspects of immunity. A progression of immune reactions occurs during granuloma formation ranging from innate inflammation, to activation of each branch of adaptive immune response, and culminating in systemic immune suppression and granuloma fibrosis. Although molecular factors from schistosome eggs have been identified as mediators of immune modulation and suppressive functions of T and B cells, much work is still needed to define the mechanisms of the immune alteration and determine whether therapies for asthma or autoimmunity could be developed from these pathways.
T helper lymphocytes; immune regulation; hygiene hypothesis; soluble egg antigen; sialyl Lewisx glycans
Experimental autoimmune encephalomyelitis (EAE) is a CD4+ T cell-mediated inflammatory demyelinating disease of the central nervous system (CNS) that serves as a model for multiple sclerosis (MS). Notch receptor signaling in T lymphocytes has been shown to regulate thymic selection and peripheral differentiation. In the present study we hypothesized that Notch ligand–receptor interaction affects EAE development by regulating encephalitogenic T cell trafficking. We demonstrate that CNS-infiltrating myeloid DC, macrophages, and resident microglia expressed Delta-like ligand 4 (DLL4) following EAE induction. Treatment of mice with a DLL4-specific blocking antibody significantly inhibited the development of clinical disease induced by active priming. Furthermore, the treatment resulted in decreased CNS accumulation of mononuclear cells in the CNS. Anti-DLL4 treatment did not significantly alter development of effector cytokine expression by antigen-specific T cells. In contrast, anti-DLL4 treatment reduced T cell mRNA and functional cell surface expression of the chemokine receptors CCR2 and CCR6. Adoptive transfer of antigen-specific T cells to mice treated with anti-DLL4 resulted in decreased clinical severity and diminished antigen-specific CD4+ T cell accumulation in the CNS. These results suggest a role for DLL4 regulation of EAE pathogenesis through modulation of T cell chemokine receptor expression and migration to the CNS.
A long-acting mutant form of a naturally occurring bacterial cocaine esterase (T172R/G173Q CocE; double mutant CocE (DM CocE)) has previously been shown to antagonize the reinforcing, convulsant, and lethal effects of cocaine in rodents. However, the effectiveness and therapeutic characteristics of DM CocE in nonhuman primates, in a more clinically relevant context, are unknown. The current studies were aimed at (1) characterizing the cardiovascular effects of cocaine in freely moving rhesus monkeys, (2) evaluating the capacity of DM CocE to ameliorate these cocaine-induced cardiovascular effects when administered 10 min after cocaine, and (3) assessing the immunological responses of monkeys to DM CocE following repeated administration. Intravenous administration of cocaine produced dose-dependent increases in mean arterial pressure (MAP) and heart rate (HR) that persisted throughout the 2-h observation period following a dose of 3.2 mg/kg cocaine. Cocaine failed to produce reliable changes in electrocardiograph (ECG) parameters, body temperature, and locomotor activity. DM CocE produced a rapid and dose-dependent amelioration of the cardiovascular effects, with saline-like MAP measures restored within 5–10 min, and saline-like HR measures restored within 20–40 min of DM CocE administration. Although administration of DM CocE produced increases in anti-CocE antibodies, they did not appear to have a neutralizing effect on the capacity of DM CocE to reverse the cardiovascular effects of cocaine. In conclusion, these findings in monkeys provide strong evidence to suggest that highly efficient cocaine esterases, such as DM CocE, can provide a potential therapeutic option for treatment of acute cocaine intoxication in humans.
rhesus monkey; cardiovascular; cocaine; acute cocaine toxicity; cocaine esterase; DM CocE; drug discovery/development; animal models; psychostimulants; addiction & substance abuse; rhesus monkey; cocaine; cardiovascular; acute toxicity; cocaine esterase
Human rhinovirus is responsible for the majority of virus-induced asthma exacerbations. To determine the immunologic mechanisms underlying rhinovirus-induced asthma exacerbations, we combined mouse models of allergic airways disease and human rhinovirus infection. We inoculated ovalbumin-sensitized and challenged BALB/c mice with rhinovirus serotype 1B, a minor group strain capable of infecting mouse cells. Compared to sham-infected, ovalbumin-treated mice, virus-infected mice showed increased lung infiltration with neutrophils, eosinophils and macrophages, airway cholinergic hyperresponsiveness, and increased lung expression of cytokines including eotaxin-1/CCL11, IL-4, IL-13 and IFN-γ. Administration of anti-eotaxin-1 attenuated rhinovirus-induced airway eosinophilia and responsiveness. Immunohistochemistry showed eotaxin-1 in the lung macrophages of virus-infected, ovalbumin-treated mice, and confocal fluorescence microscopy revealed co-localization of rhinovirus, eotaxin-1 and IL-4 in CD68-positive cells. RV inoculation of lung macrophages from ovalbumin-treated, but not PBS-treated, mice induced expression of eotaxin-1, IL-4, and IL-13 ex vivo. Macrophages from ovalbumin-treated mice showed increased expression of arginase-1, Ym-1, Mgl-2 and IL-10, indicating a shift in macrophage activation status. Depletion of macrophages from ovalbumin-sensitized and -challenged mice reduced eosinophilic inflammation and airway hyperreactivity following RV infection. We conclude that augmented airway eosinophilic inflammation and hyperresponsiveness in RV-infected mice with allergic airways disease is directed in part by eotaxin-1. Airway macrophages from mice with allergic airways disease demonstrate a change in activation state characterized in part by altered eotaxin and IL-4 production in response to RV infection. These data provide a new paradigm to explain RV-induced asthma exacerbations.