We investigated the impact of cigarette smoke exposure on respiratory immune defense mechanisms. Mice were exposed to two cigarettes daily, 5 d/wk, for 2-4 mo. Tobacco smoke decreased the number of dendritic cells (DCs) in the lung tissue. Furthermore, smoke exposure dramatically reduced the percentage of B7.1-expressing DCs. Because DCs are believed to be indispensable to the initiation of adaptive immune responses, we investigated the impact of cigarette smoke on immune responsiveness toward adenovirus. Mice were exposed to two cigarettes for 2-4 mo and inoculated with 2 x 10(8) pfu of a replication-deficient adenovirus on three occasions, 2 wk apart, during the last month of tobacco smoke exposure. Smoke exposure specifically prevented the expansion and maximal activation of CD4 T cells and reduced the number of both activated CD4 and CD8 T cells. Consequently, smoke exposure shifted the activated CD4:CD8 T cell ratio from 3 to 1.5 when compared with sham exposure. Significant decreases were also observed in serum adenovirus-specific pan IgG, IgG1, and IgG2a immunoglobulin levels, which was associated with diminished viral neutralization capacity. We demonstrate that chronic tobacco smoke exposure impairs the immune response against adenovirus. This may, in part, explain the increased prevalence of viral infections in chronic obstructive pulmonary disease.

The object of this study was to investigate the impact of cigarette smoke on bacterial clearance and immune inflammatory parameters after infection with Pseudomonas aeruginosa in mice. We observed a delayed rate of bacterial clearance in smoke-exposed compared with sham-exposed mice. This was associated with increased inflammation characterized by greater numbers of neutrophils and mononuclear cells in the bronchoalveolar lavage. After infection, we observed increased levels of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6) and chemokines (monocyte chemoattractant protein-1 [MCP-1] and macrophage inflammatory protein-2 [MIP-2]) as well as myeloperoxidase and proteolytic activity in the lungs of smoke-exposed compared with sham-exposed animals. Delayed clearance was associated with increased morbidity and greater weight loss of smoke-exposed mice. After delivery of inactivated bacteria, we observed a similar inflammatory response, clinical score, and tumor necrosis factor-alpha expression in smoke- and sham-exposed animals, suggesting that increased inflammation and altered clinical presentation are due to the delayed rate of bacterial clearance. Our findings suggest that cigarette smoke affects respiratory immune-inflammatory responses elicited by bacteria. We postulate that altered respiratory host defense may be implicated in smoking-related diseases such as chronic obstructive pulmonary disease.

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BackgroundUpon viral recognition, innate and adaptive antiviral immune responses are initiated by genital epithelial cells (ECs) to eradicate or contain viral infection. Such responses, however, are often accompanied by inflammation that contributes to acquisition and progression of sexually transmitted infections (STIs). Hence, interventions/factors enhancing antiviral protection while reducing inflammation may prove beneficial in controlling the spread of STIs. Serine antiprotease trappin-2 (Tr) and its cleaved form, elafin (E), are alarm antimicrobials secreted by multiple cells, including genital epithelia.Methodology and Principal FindingsWe investigated whether and how each Tr and E (Tr/E) contribute to antiviral defenses against a synthetic mimic of viral dsRNA, polyinosine-polycytidylic acid (polyI∶C) and vesicular stomatitis virus. We show that delivery of a replication-deficient adenovector expressing Tr gene (Ad/Tr) to human endometrial epithelial cells, HEC-1A, resulted in secretion of functional Tr, whereas both Tr/E were detected in response to polyI∶C. Moreover, Tr/E were found to significantly reduce viral replication by either acting directly on virus or through enhancing polyI∶C-driven antiviral protection. The latter was associated with reduced levels of pro-inflammatory factors IL-8, IL-6, TNFα, lowered expression of RIG-I, MDA5 and attenuated NF-κB activation. Interestingly, enhanced polyI∶C-driven antiviral protection of HEC-Ad/Tr cells was partially mediated through IRF3 activation, but not associated with higher induction of IFNβ, suggesting multiple antiviral mechanisms of Tr/E and the involvement of alternative factors or pathways.Conclusions and SignificanceThis is the first evidence of both Tr/E altering viral binding/entry, innate recognition and mounting of antiviral and inflammatory responses in genital ECs that could have significant implications for homeostasis of the female genital tract.

The majority of infants who breastfeed from their HIV-positive mothers remain uninfected despite constant and repeated exposure to virus over weeks to years. This phenomenon is not fully understood but has been closely linked to innate factors in breast milk (BM). Most recently we have focused on one such innate factor, soluble Toll-like receptor 2 (sTLR2) for its significant contribution as an inhibitor of inflammation triggered by bacterial and viral antigens. We hypothesized that sTLR2 in BM inhibits immune activation/inflammation and HIV-1 infection. sTLR2 protein profiles were analyzed in HIV-uninfected BM and showed dramatic variability in expression concentration and predominant sTLR2 forms between women. sTLR2 immunodepleted BM, versus mock-depleted BM, incubated with Pam3CSK4 lead to significant increases in IL-8 production in a TLR2-dependant fashion in U937, HEK293-TLR2, and Caco-2. Importantly, TLR2-specific polyclonal and monoclonal antibody addition to BM prior to cell-free R5 HIV-1 addition led to significantly (P<0.01, P<0.001, respectively) increased HIV-1 infection in TZM-bl reporter cells. To confirm these findings, sTLR2-depletion in BM led to significantly (P<0.001) increased HIV-1 infection in TZM-bl cells. Notably, immunodepletion does not allow for the complete removal of sTLR2 from BM, thus functional testing shown here may underestimate the total effect elicited by sTLR2 against HIV-1 and synthetic bacterial ligand. This study provides evidence for the first time that sTLR2 in BM may provide a dual protective role for infants breastfeeding from their HIV-infected mothers by; (1) immunomodulating pro-inflammatory responses to bacterial ligands, and (2) directly inhibiting cell-free HIV-1 infection. Thus, sTLR2 in BM may be critical to infant health and prove beneficial in decreasing vertical HIV-1 transmission to infants.

These results indicate novel mechanisms by which sTLR2 plays a critical role in inhibiting mother-to-child HIV transmission.

Despite tremendous advances in our understanding of HIV/AIDS since the first cases were reported 30 years ago, we are still a long way from understanding critical steps of HIV acquisition, pathogenesis and correlates of protection. Our new understanding of the importance of the mucosa as a target for HIV infection, as well as our recent observations showing that altered expression and responses of innate pattern recognition receptors are significantly associated with pathogenesis and resistance to HIV infection, indicate that correlates of immunity to HIV are more likely to be associated with mucosal and innate responses. Most of the heterosexual encounters do not result in productive HIV infection, suggesting that the female genital tract is protected against HIV by innate defence molecules, such as antiproteases, secreted mucosally. The present review highlights the role and significance of the serine protease inhibitors SLPI (secretory leucocyte protease inhibitor), trappin-2, elafin and ps20 (prostate stromal protein 20 kDa) in HIV susceptibility and infection. Interestingly, in contrast with SLPI, trappin-2 and elafin, ps20 has been shown to enhance HIV infectivity. Thus understanding the balance and interaction of these factors in mucosal fluids may significantly influence HIV infection.

The developmental morphogen Sonic hedgehog (Shh) may continue to play a sustaining role in adult motor neurons, of potential relevance to motor neuron diseases including amyotrophic lateral sclerosis. The Shh signaling pathway is incompletely understood and interactions with other signaling pathways are possible. We focus here on Notch, and first show that there is an almost linear reduction in light output from a Gli reporter in Shh Light II cells in the presence of increasing concentrations of the Notch inhibitor DAPT (r2=0.982). Second, in the spinal cord of mutant superoxide dismutase mice, but not control mice, a key marker of Notch signaling changes with age. Before the onset of clinical signs, the Notch intracellular domain is expressed predominantly in motor neurons, but by 125 days of age, Notch intracellular domain expression is markedly reduced in motor neurons and increased in neighboring astroglia. Third, there is a parallel reduction in Gli protein expression in mutant superoxide dismutase mouse spinal motor neurons, consistent with the observed reduction in Notch signaling and also a redistribution of Gli away from the nucleus. Thus, there is a reduction in motor neuronal Notch signaling and associated changes in Shh signaling, occurring coincidentally with disease expression, that may contribute toward the dysfunction and death of motor neurons in amyotrophic lateral sclerosis.