Silicosis, a fibrotic granulomatous lung disease, may occur through accidental high-dose or occupational inhalation of silica, leading to acute/accelerated and chronic silicosis, respectively. While chronic silicosis has a long asymptomatic latency, lung inflammation and apoptosis are hallmarks of acute silicosis. In animal models, histiocytic granulomas develop within days after high-dose intratracheal (IT) silica instillation. However, following chronic inhalation of occupationally relevant doses of silica, discrete granulomas resembling human silicosis arise months after the final exposure without significant lung inflammation/apoptosis. To identify molecular events associated with chronic silicosis, lung RNAs from controls or sub-chronic silica-exposed rats were analyzed by Affymetrix at 28 weeks after silica exposures. Results suggested a significant upregulation of 144 genes and downregulation of 7 genes. The upregulated genes included complement cascade, chemokines/chemokine receptors, G-protein signaling components, metalloproteases, and genes associated with oxidative stress. To examine the kinetics of gene expression relevant to silicosis, qPCR, ELISA, Luminex-bead assays, Western blotting, and/or zymography were performed on lung tissues from 4 day, 28 week, and intermediate times after sub-chronic silica exposure and compared with 14 day acute silicosis samples. Results indicated that genes regulating fibrosis (secreted phosphoprotein-1, Ccl2, and Ccl7), redox enzymes (superoxide dismutase-2 and arginase-1), and the enzymatic activities of matrix metalloproteinases 2 and 9 were upregulated in acute and chronic silicosis models. However, proinflammatory cytokines were strongly upregulated only in acute silicosis. Thus, inflammatory cytokines are associated with acute but not chronic silicosis. Data suggest that genes regulating fibrosis, oxidative stress, and metalloproteases may contribute to both acute and chronic silicosis.
Silicosis; Fibrosis; Inflammation; Spp1; Ccl2; Ccl7; Toxicogenomic
Aggressive diagnosis and treatment of patients presenting to the emergency department (ED) with septic shock has been shown to reduce mortality. To enhance the ability to intervene in patients with lesser illness severity, a better understanding of the natural history of the early progression from simple infection to more severe illness is needed.
The objectives were to 1) describe the clinical presentation of ED sepsis, including types of infection and causative microorganisms, and 2) determine the incidence, patient characteristics, and mortality associated with early progression to septic shock among ED patients with infection.
This was a multicenter study of adult ED patients with sepsis but no evidence of shock. Multivariable logistic regression was used to identify patient factors for early progression to shock and its association with 30-day mortality.
Of 472 patients not in shock at ED presentation (systolic blood pressure > 90 mm Hg and lactate < 4 mmol / L), 84 (17.8%) progressed to shock within 72 hours. Independent factors associated with early progression to shock included older age, female sex, hyperthermia, anemia, comorbid lung disease, and vascular access device infection. Early progression to shock (vs. no progression) was associated with higher 30-day mortality (13.1% vs. 3.1%, odds ratio [OR] = 4.72, 95% confidence interval [CI] = 2.01 to 11.1; p ≤ 0.001). Among 379 patients with uncomplicated sepsis (i.e., no evidence of shock or any end-organ dysfunction), 86 (22.7%) progressed to severe sepsis or shock within 72 hours of hospital admission.
A significant portion of ED patients with less severe sepsis progress to severe sepsis or shock within 72 hours. Additional diagnostic approaches are needed to risk stratify and more effectively treat ED patients with sepsis.
sepsis; outcomes; septic shock; progression; biomarkers
Sepsis, a leading cause of morbidity and mortality, is not a homogeneous disease but rather a syndrome encompassing many heterogeneous pathophysiologies. Patient factors including genetics predispose to poor outcomes, though current clinical characterizations fail to identify those at greatest risk of progression and mortality.
The Community Acquired Pneumonia and Sepsis Outcome Diagnostic study enrolled 1,152 subjects with suspected sepsis. We sequenced peripheral blood RNA of 129 representative subjects with systemic inflammatory response syndrome (SIRS) or sepsis (SIRS due to infection), including 78 sepsis survivors and 28 sepsis non-survivors who had previously undergone plasma proteomic and metabolomic profiling. Gene expression differences were identified between sepsis survivors, sepsis non-survivors, and SIRS followed by gene enrichment pathway analysis. Expressed sequence variants were identified followed by testing for association with sepsis outcomes.
The expression of 338 genes differed between subjects with SIRS and those with sepsis, primarily reflecting immune activation in sepsis. Expression of 1,238 genes differed with sepsis outcome: non-survivors had lower expression of many immune function-related genes. Functional genetic variants associated with sepsis mortality were sought based on a common disease-rare variant hypothesis. VPS9D1, whose expression was increased in sepsis survivors, had a higher burden of missense variants in sepsis survivors. The presence of variants was associated with altered expression of 3,799 genes, primarily reflecting Golgi and endosome biology.
The activation of immune response-related genes seen in sepsis survivors was muted in sepsis non-survivors. The association of sepsis survival with a robust immune response and the presence of missense variants in VPS9D1 warrants replication and further functional studies.
ClinicalTrials.gov NCT00258869. Registered on 23 November 2005.
Electronic supplementary material
The online version of this article (doi:10.1186/s13073-014-0111-5) contains supplementary material, which is available to authorized users.
Sepsis is a common cause of death, but outcomes in individual patients are difficult to predict. Elucidating the molecular processes that differ between sepsis patients who survive and those who die may permit more appropriate treatments to be deployed. We examined the clinical features, and the plasma metabolome and proteome of patients with and without community-acquired sepsis, upon their arrival at hospital emergency departments and 24 hours later. The metabolomes and proteomes of patients at hospital admittance who would die differed markedly from those who would survive. The different profiles of proteins and metabolites clustered into fatty acid transport and β-oxidation, gluconeogenesis and the citric acid cycle. They differed consistently among several sets of patients, and diverged more as death approached. In contrast, the metabolomes and proteomes of surviving patients with mild sepsis did not differ from survivors with severe sepsis or septic shock. An algorithm derived from clinical features together with measurements of seven metabolites predicted patient survival. This algorithm may help to guide the treatment of individual patients with sepsis.
Lung diseases such as chronic obstructive pulmonary disease (COPD), asthma, and lung infections are major causes of morbidity and mortality among HIV-infected patients even in the era of antiretroviral therapy (ART). Many of these diseases are strongly associated with smoking and smoking is more common among HIV-infected than uninfected people; however, HIV is an independent risk factor for chronic bronchitis, COPD, and asthma. The mechanism by which HIV promotes these diseases is unclear. Excessive airway mucus formation is a characteristic of these diseases and contributes to airway obstruction and lung infections. HIV gp120 plays a critical role in several HIV-related pathologies and we investigated whether HIV gp120 promoted airway mucus formation in normal human bronchial epithelial (NHBE) cells. We found that NHBE cells expressed the HIV-coreceptor CXCR4 but not CCR5 and produced mucus in response to CXCR4-tropic gp120. The gp120-induced mucus formation was blocked by the inhibitors of CXCR4, α7-nicotinic acetylcholine receptor (α7-nAChR), and γ-aminobutyric acid (GABA)AR but not the antagonists of CCR5 and epithelial growth factor receptor (EGFR). These results identify two distinct pathways (α7-nAChR-GABAAR and EGFR) for airway mucus formation and demonstrate for the first time that HIV-gp120 induces and regulates mucus formation in the airway epithelial cells through the CXCR4-α7-nAChR-GABAAR pathway. Interestingly, lung sections from HIV ± ART and simian immunodeficiency virus (SIV) ± ART have significantly more mucus and gp120-immunoreactivity than control lung sections from humans and macaques, respectively. Thus, even after ART, lungs from HIV-infected patients contain significant amounts of gp120 and mucus that may contribute to the higher incidence of obstructive pulmonary diseases in this population.
Airway mucus hypersecretion is a key pathophysiological feature in number of lung diseases. Cigarette smoke/nicotine and allergens are strong stimulators of airway mucus; however, the mechanism of mucus modulation is unclear.
Characterize the pathway by which cigarette smoke/nicotine regulates airway mucus and identify agents that decrease airway mucus.
IL-13 and gamma-aminobutyric acid receptors (GABAARs) are implicated in airway mucus. We examined the role of IL-13 and GABAARs in nicotine-induced mucus formation in normal human bronchial epithelial (NHBE) and A549 cells, and secondhand cigarette smoke and/or ovalbumin-induced mucus formation in vivo.
Nicotine promotes mucus formation in NHBE cells; however, the nicotine-induced mucus formation is independent of IL-13 but sensitive to the GABAAR antagonist picrotoxin (PIC). Airway epithelial cells express α7/α9/α10 nicotinic acetylcholine receptors (nAChRs) and specific inhibition or knockdown of α7- but not α9/α10-nAChRs abrogates mucus formation in response to nicotine and IL-13. Moreover, addition of acetylcholine or inhibition of its degradation increases mucus in NHBE cells. Nicotinic but not muscarinic receptor antagonists block allergen or nicotine/cigarette smoke-induced airway mucus formation in NHBE cells and/or in mouse airways.
Nicotine-induced airway mucus formation is independent of IL-13 and α7-nAChRs are critical in airway mucous cell metaplasia/hyperplasia and mucus production in response to various pro-mucoid agents, including IL-13. In the absence of nicotine, acetylcholine may be the biological ligand for α7-nAChRs to trigger airway mucus formation. α7-nAChRs are downstream of IL-13 but upstream of GABAARα2 in the MUC5AC pathway. Acetylcholine and α-7-nAChRs may serve as therapeutic targets to control airway mucus.
cigarette smoke; nicotine; nicotinic acetylcholine receptors; gamma-aminobutyric acid receptors; acetylcholine; airway mucus
Circulating biomarkers can facilitate sepsis diagnosis enabling early management and improved outcomes. Procalcitonin (PCT) has been suggested to have superior diagnostic utility compared to other biomarkers.
Adults with suspected sepsis in the Emergency Department were enrolled. PCT, CRP, and IL-6 were correlated with infection likelihood, sepsis severity, and septicemia. Multivariable models were constructed for length-of-stay and discharge to a higher level of care.
Of 336 enrolled subjects, 60% had definite infection, 13% possible infection and 27% no infection. Of those with infection, 202 presented with sepsis, 28 with severe sepsis, and 17 with septic shock. Overall, 21% of subjects were septicemic. PCT, IL6, and CRP levels were significantly higher in septicemia (median PCT 2.3 vs. 0.2ng/mL; IL-6 178 vs. 72pg/mL; CRP 106 vs. 62mg/dL, p<0.001). Biomarker concentrations increased with greater likelihood of infection and sepsis severity. Using ROC analysis, PCT best predicted septicemia (0.78 vs. IL-6 0.70 and CRP 0.67) but CRP better identified clinical infection (0.75 vs. PCT 0.71 and IL-6 0.69). A PCT cut-off of 0.5ng/mL had 72.6% sensitivity and 69.5% specificity for bacteremia as well as 40.7% sensitivity and 87.2% specificity for diagnosing infection. A combined clinical-biomarker model revealed that CRP was marginally associated with length-of-stay (p=0.015), but no biomarker independently predicted discharge to a higher level of care.
In adult Emergency Department patients with suspected sepsis, PCT, IL-6, and CRP highly correlate with several infection parameters, but do not meaningfully predict length-of-stay or need for discharge to a higher level of care.
Sepsis; Procalcitonin; Interleukin-6; C-Reactive Protein; Sensitivity and Specificity
Background: Cigarette smoke (CS) exposure during gestation may increase the risk of bronchopulmonary dysplasia (BPD)—a developmental lung condition primarily seen in neonates that is characterized by hypoalveolarization, decreased angiogenesis, and diminished surfactant protein production and may increase the risk of chronic obstructive pulmonary disease.
Objective: We investigated whether gestational exposure to secondhand CS (SS) induced BPD and sought to ascertain the role of nicotinic acetylcholine receptors (nAChRs) in this response.
Methods: We exposed BALB/c and C57BL/6 mice to filtered air (control) or SS throughout the gestation period or postnatally up to 10 weeks. Lungs were examined at 7 days, 10 weeks, and 8 months after birth.
Results: Gestational but not postnatal exposure to SS caused a typical BPD-like condition: suppressed angiogenesis [decreased vascular endothelial growth factor (VEGF), VEGF receptor, and CD34/CD31 (hematopoietic progenitor cell marker/endothelial cell marker)], irreversible hypoalveolarization, and significantly decreased levels of Clara cells, Clara cell secretory protein, and surfactant proteins B and C, without affecting airway ciliated cells. Importantly, concomitant exposure to SS and the nAChR antagonist mecamylamine during gestation blocked the development of BPD.
Conclusions: Gestational exposure to SS irreversibly disrupts lung development leading to a BPD-like condition with hypoalveolarization, decreased angiogenesis, and diminished lung secretory function. Nicotinic receptors are critical in the induction of gestational SS–induced BPD, and the use of nAChR antagonists during pregnancy may block CS-induced BPD.
angiogenesis; bronchopulmonary dysplasia; cigarette smoke; nicotinic receptors; secretory/surfactant proteins
Sulfur mustard (SM) is a highly toxic chemical warfare agent that remains a threat to human health. The immediate symptoms of pulmonary distress may develop into chronic lung injury characterized by progressive lung fibrosis, the major cause of morbidity among the surviving SM victims. Although SM has been intensely investigated, little is known about the mechanism(s) by which SM induces chronic lung pathology. Increasing evidence suggests that IL-17+ cells are critical in fibrosis, including lung fibrotic diseases. In this study we exposed F344 rats and cynomolgus monkeys to SM via inhalation and determined the molecular and cellular milieu in their lungs at various times after SM exposure. In rats, SM induced a burst of pro-inflammatory cytokines/chemokines within 72 h, including IL-1β, TNF-α, IL-2, IL-6, CCL2, CCL3, CCL11, and CXCL1 that was associated with neutrophilic infiltration into the lung. At 2 wk and beyond (chronic phase), lymphocytic infiltration and continued elevated expression of cytokines/chemokines were sustained. TGF-β, which was undetectable in the acute phase, was strongly upregulated in the chronic phase; these conditions persisted until the animals were sacrificed. The chronic phase was also associated with myofibroblast proliferation, collagen deposition, and presence of IL-17+ cells. At 30 days, SM inhalation promoted the accumulation of IL-17+ cells in the inflamed areas of monkey lungs. Thus, SM inhalation causes acute and chronic inflammatory responses; the latter is characterized by the presence of TGF-β, fibrosis, and IL-17+ cells in the lung. IL-17+ cells likely play an important role in the pathogenesis of SM-induced lung injury.
Sulfur mustard; Inflammation; Apoptosis; Fibrosis; Cytokine
Staphylococcus aureus causes a spectrum of human infection. Diagnostic delays and uncertainty lead to treatment delays and inappropriate antibiotic use. A growing literature suggests the host’s inflammatory response to the pathogen represents a potential tool to improve upon current diagnostics. The hypothesis of this study is that the host responds differently to S. aureus than to E. coli infection in a quantifiable way, providing a new diagnostic avenue. This study uses Bayesian sparse factor modeling and penalized binary regression to define peripheral blood gene-expression classifiers of murine and human S. aureus infection. The murine-derived classifier distinguished S. aureus infection from healthy controls and Escherichia coli-infected mice across a range of conditions (mouse and bacterial strain, time post infection) and was validated in outbred mice (AUC>0.97). A S. aureus classifier derived from a cohort of 94 human subjects distinguished S. aureus blood stream infection (BSI) from healthy subjects (AUC 0.99) and E. coli BSI (AUC 0.84). Murine and human responses to S. aureus infection share common biological pathways, allowing the murine model to classify S. aureus BSI in humans (AUC 0.84). Both murine and human S. aureus classifiers were validated in an independent human cohort (AUC 0.95 and 0.92, respectively). The approach described here lends insight into the conserved and disparate pathways utilized by mice and humans in response to these infections. Furthermore, this study advances our understanding of S. aureus infection; the host response to it; and identifies new diagnostic and therapeutic avenues.
Parental, particularly maternal, smoking increases the risk of childhood allergic asthma and infection. Similarly, in a murine allergic asthma model, prenatal plus early postnatal exposure to secondhand cigarette smoke (SS) exacerbates airway hyperreactivity and Th2 responses in the lung. However, the mechanism and contribution of prenatal versus early postnatal SS exposure on allergic asthma remains unresolved. To identify the effects of prenatal and/or early postnatal SS on allergic asthma, BALB/c dams and their offspring were exposed gestationally and/or 8–10 weeks post-birth to filtered air or SS. Prenatal, but not postnatal SS strongly increased methacholine and allergen (Aspergillus)-induced airway resistance, Th2-cytokines levels and atopy, and activated the Th2 polarizing pathway GATA3/Lck/ERK1/2/STAT6. Either prenatal and/or early postnatal SS downregulated the Th1-specific transcription factor T-bet and, surprisingly, in spite of high levels of IL-4/IL-13, dramatically blocked the allergen-induced mucous cell metaplasia, airway mucus formation, and the expression of mucus-related genes/proteins: Muc5ac, GABAA-receptors, and SPDEF. Given that SS/nicotine exposure of normal adult mice promotes mucus formation, the results suggest that fetal and neonatal lung are highly sensitive to cigarette smoke. Thus, while the gestational SS promotes Th2 polarization/allergic asthma, it may also impair and/or delay the development of fetal and neonatal lung, affecting mucociliary clearance and Th1 responses. Together, this may explain the increased susceptibility of children from smoking parents to allergic asthma and childhood respiratory infections.
Environmental (secondhand) tobacco smoke; airways hyperreactivity; allergic asthma; Th2 polarization; airway mucus
Smokers are less likely to develop some inflammatory and allergic diseases. In Brown-Norway rats, nicotine inhibits several parameters of allergic asthma including the production of Th2 cytokines and the cysteinyl leukotriene LTC4. Cysteinyl leukotrienes are primarily produced by mast cells, and these cells play a central role in allergic asthma. Mast cells express a high affinity receptor for IgE (FcεRI). Following its cross-linking, cells degranulate and release preformed inflammatory mediators (early phase), and synthesize and secrete cytokines/chemokines and leukotrienes (late phase). The mechanism by which nicotine modulates mast cell activation is unclear. Using α-bungarotoxin binding, qPCR, and PCR product sequencing, we show that the rat mast/basophil cell line RBL-2H3 express nicotinic acetylcholine receptors (nAChRs) α7, α9, and α10, and exposure to exceedingly low concentrations of nicotine (nanomolar), but not the biologically inactive metabolite cotinine for ≥8h suppressed the late phase (leukotriene/cytokine production) but not degranulation (histamine and hexosaminidase release). These effects were unrelated to those of nicotine on intracellular free calcium concentration but causally associated with the inhibition of cPLA2 activity and PI3K/ERK/NF-κB pathway, including phosphorylation of Akt and ERK, and nuclear translocation of NF-κB. The suppressive effect of nicotine on the late-phase response was blocked by the α7/α9-nAChRs antagonist methyllycaconitine and α-bungarotoxin, and by siRNA knockdown of α7, α9, or α10 nAChRs, suggesting a functional interaction between α7, α9, and α10 nAChRs that might explain the response of RBL to nanomolar concentrations of nicotine. This “hybrid” receptor might serve as a target for novel anti-allergic/asthmatic therapies.
Chronic human silicosis results primarily from continued occupational exposure to silica and exhibits a long asymptomatic latency. Similarly, continued exposure of Lewis rats to low doses of silica is known to cause delayed granuloma formation with limited lung inflammation and injury. On the other hand, intratracheal exposure to large doses of silica induces acute silicosis characterized by granuloma-like formations in the lung associated with apoptosis, severe alveolitis, and alveolar lipoproteinosis. To ascertain similarities/differences between acute and chronic silicosis, in this communication, we compared cellular and molecular changes in established rat models of acute and chronic silicosis. In Lewis rats, acute silicosis was induced by intratracheal instillation of 35 mg silica, and chronic silicosis through inhalation of aerosolized silica (6.2 mg/m3, 5 days/week for 6 weeks). Animals exposed to acute high-dose silica were sacrificed at 14 days after silica instillation while chronically silica-treated animals were sacrificed between 4 days and 28 wk after silica exposure. The lung granulomas formation in acute silicosis was associated with strong inflammation, presence of TUNEL-positive cells and increases in caspase-3 activity and other molecular markers of apoptosis. On the other hand, lungs from chronically silica-exposed animals exhibited limited inflammation and increased expression of anti-apoptotic markers, including dramatic increases in Bcl-2 and procaspase-3, and lower caspase-3 activity. Moreover, chronic silicotic lungs were TUNEL-negative and overexpressed Bcl-3 and NF-κB-p50 but not NF-κB-p65 subunits. These results suggest that, unlike acute silicosis, chronic exposures to occupationally relevant doses of silica causes significantly lower lung inflammation and elevated expression of anti-apoptotic rather than proapoptotic markers in the lung that might result from interaction between NF-κB-p50 and Bcl-3.
silicosis; apoptosis; lung inflammation; granuloma
Meiosis is a critical process in the reproduction and life cycle of flowering plants in which homologous chromosomes pair, synapse, recombine and segregate. Understanding meiosis will not only advance our knowledge of the mechanisms of genetic recombination, but also has substantial applications in crop improvement. Despite the tremendous progress in the past decade in other model organisms (e.g., Saccharomyces cerevisiae and Drosophila melanogaster), the global identification of meiotic genes in flowering plants has remained a challenge due to the lack of efficient methods to collect pure meiocytes for analyzing the temporal and spatial gene expression patterns during meiosis, and for the sensitive identification and quantitation of novel genes.
A high-throughput approach to identify meiosis-specific genes by combining isolated meiocytes, RNA-Seq, bioinformatic and statistical analysis pipelines was developed. By analyzing the studied genes that have a meiosis function, a pipeline for identifying meiosis-specific genes has been defined. More than 1,000 genes that are specifically or preferentially expressed in meiocytes have been identified as candidate meiosis-specific genes. A group of 55 genes that have mitochondrial genome origins and a significant number of transposable element (TE) genes (1,036) were also found to have up-regulated expression levels in meiocytes.
These findings advance our understanding of meiotic genes, gene expression and regulation, especially the transcript profiles of MGI genes and TE genes, and provide a framework for functional analysis of genes in meiosis.
Sepsis is caused by a heterogeneous group of infectious etiologies. Early diagnosis and the provision of appropriate antimicrobial therapy correlate with positive clinical outcomes. Current microbiological techniques are limited in their diagnostic capacities and timeliness. Multiplex PCR has the potential to rapidly identify bloodstream infections and fill this diagnostic gap. We identified patients from two large academic hospital emergency departments with suspected sepsis. The results of a multiplex PCR that could detect 25 bacterial and fungal pathogens were compared to those of blood culture. The results were analyzed with respect to the likelihood of infection, sepsis severity, the site of infection, and the effect of prior antibiotic therapy. We enrolled 306 subjects with suspected sepsis. Of these, 43 were later determined not to have infectious etiologies. Of the remaining 263 subjects, 70% had sepsis, 16% had severe sepsis, and 14% had septic shock. The majority had a definite infection (41.5%) or a probable infection (30.7%). Blood culture and PCR performed similarly with samples from patients with clinically defined infections (areas under the receiver operating characteristic curves, 0.64 and 0.60, respectively). However, blood culture identified more cases of septicemia than PCR among patients with an identified infectious etiology (66 and 46, respectively; P = 0.0004). The two tests performed similarly when the results were stratified by sepsis severity or infection site. Blood culture tended to detect infections more frequently among patients who had previously received antibiotics (P = 0.06). Conversely, PCR identified an additional 24 organisms that blood culture failed to detect. Real-time multiplex PCR has the potential to serve as an adjunct to conventional blood culture, adding diagnostic yield and shortening the time to pathogen identification.
High-throughput DNA sequencing has enabled systems biology to begin to address areas in health, agricultural and basic biological research. Concomitant with the opportunities is an absolute necessity to manage significant volumes of high-dimensional and inter-related data and analysis. Alpheus is an analysis pipeline, database and visualization software for use with massively parallel DNA sequencing technologies that feature multi-gigabase throughput characterized by relatively short reads, such as Illumina-Solexa (sequencing-by-synthesis), Roche-454 (pyrosequencing) and Applied Biosystem’s SOLiD (sequencing-by-ligation). Alpheus enables alignment to reference sequence(s), detection of variants and enumeration of sequence abundance, including expression levels in transcriptome sequence. Alpheus is able to detect several types of variants, including non-synonymous and synonymous single nucleotide polymorphisms (SNPs), insertions/deletions (indels), premature stop codons, and splice isoforms. Variant detection is aided by the ability to filter variant calls based on consistency, expected allele frequency, sequence quality, coverage, and variant type in order to minimize false positives while maximizing the identification of true positives. Alpheus also enables comparisons of genes with variants between cases and controls or bulk segregant pools. Sequence-based differential expression comparisons can be developed, with data export to SAS JMP Genomics for statistical analysis.
Alpheus; sequencing-by-synthesis; pyrosequencing; GMAP; GSNAP; resequencing; transcriptome sequencing
Allergic asthma, an inflammatory disease characterized by infiltration and activation of various leukocytes, production of Th2 cytokines and leukotrienes, and atopy, also affects the function of other cell types, causing goblet cell hyperplasia/hypertrophy, increased mucus production/secretion, and airway hyperreactivity. Eosinophilic inflammation is a characteristic feature of human asthma, and recent evidence suggests that eosinophils also play a critical role in T cell trafficking in animal models of asthma. Nicotine is an anti-inflammatory, but the association between smoking and asthma is highly contentious, and some report that smoking cessation increases the risk of asthma in ex-smokers. To ascertain the effects of nicotine on allergy/asthma, Brown Norway rats were treated with nicotine, and sensitized and challenged with allergens. Results unequivocally show that, even after multiple allergen sensitizations, nicotine dramatically suppresses inflammatory/allergic parameters in the lung, including eosinophilic/lymphocytic emigration; mRNA and/or protein expression of Th2 cytokines/chemokines IL-4, IL-5, IL-13, IL-25, and eotaxin; leukotriene C4; and total as well as allergen-specific IgE. While nicotine did not significantly affect hexosaminidase release, IgG, or methacholine-induced airway resistance, it significantly decreased mucus content in bronchoalveolar lavage; interestingly, however, in spite of the strong suppression of IL-4/IL-13, nicotine significantly increased the intraepithelial stored mucosubstances, and Muc5ac mRNA expression. These results suggest that nicotine modulates allergy/asthma primarily by suppressing eosinophil trafficking and suppressing Th2 cytokine/chemokine responses without reducing goblet cell metaplasia, mucous production, and may explain the lower risk of allergic diseases in smokers. To our knowledge this is the first direct evidence that nicotine modulates allergic responses.
To study the immunological effects of nicotine, there are several rodent models for chronic nicotine administration. These models include subcutaneously implanted miniosmotic pumps, nicotine-spiked drinking water, and self-administration via jugular cannulae. Administration of nicotine via these routes affects the immune system. Smokers frequently use nicotine patches to quit smoking, and the immunological effects of nicotine patches are largely unknown. To determine whether the nicotine patch affects the immune system, nicotine patches were affixed daily onto the backs of Lewis rats for 3 to 4 weeks. The patches efficiently raised the levels of nicotine and cotinine in serum and strongly inhibited the antibody-forming cell response of spleen cells to sheep red blood cells. The nicotine patch also suppressed the concanavalin A-induced T-cell proliferation and mobilization of intracellular Ca2+ by spleen cells, as well as the fever response of animals to subcutaneous administration of turpentine. Moreover, immunosuppression was associated with chronic activation of protein tyrosine kinase and phospholipase C-γ1 activities. Thus, in this animal model of nicotine administration, the nicotine patch efficiently raises the levels of nicotine and cotinine in serum and impairs both the immune and inflammatory responses.