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Rationale: Tumor necrosis factor-alpha (TNF-α) is a potent pro-inflammatory mediator and its expression is up-regulated in chronic obstructive pulmonary disease (COPD). Tristetraprolin (TTP) is implicated in regulation of TNF-α expression; however, whether TTP is involved in cigarette smoke-induced TNF-α expression has not been determined. Methods: TTP expression was examined by western blot analysis in murine alveolar macrophages and alveolar epithelial cells challenged without or with cigarette smoke extract (CSE). TNF-α mRNA stability, and the decay of TNF-α mRNA, were determined by real-time quantitative RT-PCR. TNF-α protein levels were examined at the same time in these cells. To identify the molecular mechanism involved, a construct expressing the human beta-globin reporter mRNA containing the TNF-α 3’-untranslated region was generated to characterize the TTP targeted site within TNF-α mRNA. Results: CSE induced TTP down-regulation in alveolar macrophages and alveolar epithelial cells. Reduced TTP expression resulted in significantly increased TNF-α mRNA stability. Importantly, increased TNF-α mRNA stability due to impaired TTP function resulted in significantly increased TNF-α levels in these cells. Forced TTP expression abrogated the increased TNF-α mRNA stability and expression induced by CSE. By using the globin reporter construct containing TNF-α mRNA 3’-untranslated region, the data indicate that TTP directly targets the adenine- and uridine-rich region (ARE) of TNF-α mRNA and negatively regulates TNF-α expression at the post-transcriptional level. Conclusion: The data demonstrate that cigarette smoke exposure reduces TTP expression and impairs TTP function, resulting in significantly increased TNF-α mRNA stability and excessive TNF-α expression in alveolar macrophages and epithelial cells. The data suggest that TTP is a novel post-transcriptional regulator and limits excessive TNF-α expression and inflammatory response induced by cigarette smoke. [ABSTRACT FROM AUTHOR]

ALR mice are unusually resistant to T1D. Genetic elements responsible for the ALR-derived T1D resistance were identified via analysis of outcross/backcross cohorts of ALR with T1D-prone NOD. We have previously demonstrated that NADPH Oxidase (NOX) in ALR cells is inhibited. Genetic analyses have mapped inhibited NOX to a locus on Chromosome (Chr.) 3 [Suppressor of Superoxide Production (Susp)] that is also in linkage disequilibrium with ALR-derived T1D resistance. To directly determine the impact of NOX inhibition on T1D initiation, NOX-inactive NOD mice (NOD-Ncf1µ) were bred. NOD-Ncf1µ mice have significantly reduced incidence of T1D (10%) versus 85% in Ncf1 intact littermate controls and were resistant to the adoptive transfer of diabetogenic BDC2.5 CD4+ T cell clones, demonstrating that NOX plays an important role in T1D pathogenesis. To identify the gene encoded by Susp and determine the mechanism of protection, ten recombinant congenic strains (RCS), with overlapping intervals on Chr. 3, have been generated. ALR x NOD F1 hybrids demonstrated an intermediate O2• production compared to ALR (Low O2• production) and NOD (High O2• production) supporting co-dominant mode of inheritance. Using the RCS we have reduced the size of the interval containing Susp from 45 cM to 19 cM. Experiments have also been performed comparing immune system function from mice with and without NOX activity that result in T1D protection.. Splenocytes from NOD, NOD-Ncf1µ, and ALR mice were activated to assess cytokine production. Activation of NOD splenocytes led to a Th1 cytokine secretion profile as exemplified by higher levels of IFN-γ (p<0.05) and TNFα (p<0.05) synthesis when compared to NOD-Ncf1µ or ALR splenocytes. In contrast, activated NOD-Ncf1µ and ALR splenocytes secreted a cytokine profile indicative of a Th17 response as observed by higher levels of IL-17 (p<0.01) and IL-10 (p<0.05) in comparison to NOD splenocytes. In conclusion, inhibition of NOX is protective against T1D and inhibition of immune cell O2• appears to skew immune responses away from a pathogenic Th1 and towards a potentially non-pathogenic Th17 response. These results also support a role for 02• production in polarizing an immune response. [ABSTRACT FROM AUTHOR]

Abstract: Pulmonary infection caused by the opportunistic fungal organism Pneumocystis continues to be a leading AIDS defining illness. The initiation of highly active antiretroviral therapy (HAART) in the HIV-infected population has led to a significant reduction in the incidence of Pneumocystis pneumonia (PCP), although recent trends suggest the incidence has plateaued rather than decreased. Host defense against Pneumocystis involves a delicate, concerted balance between the inflammatory response and immune-mediated clearance. Innate cellular immunity is a cornerstone in this response as it provides the initial recognition event that precipitates an immune response, ultimately leading to clearance of the organism from the host. This review will focus on carbohydrate moieties found in the Pneumocystis cell wall and the immune events that occur following their recognition. [Copyright &y& Elsevier]

Sensitization to fungi, such as the mold Aspergillus fumigatus, is increasingly becoming linked with asthma severity. We have previously shown that lung responses generated via the β-glucan receptor Dectin-1 are required for lung defense during acute, invasive A. fumigatus infection. Unexpectedly, in an allergic model of chronic lung exposure to li\e A. fumigatus conidia, β-glucan recognition via Dectin-1 led to the induction of multiple proallergic (Muc5ac, Clca3, CCL17, CCL22, and IL-33) and proinflam-matory (IL-1β and CXCL1) mediators that compromised lung function. Attenuated proallergic and proinflammatory responses in the absence of Dectin-1 were not associated with changes in Ido (IDO), Ill2p35/Ebi3 (IL-35), IL-10, or TGF-β levels. Assessment of Th responses demonstrated that purified lung CD4+ T cells produced IL-4, IL-13, IFN-&ggr;, and IL-17A, but not IL-22, in a Dectin-1-dependent manner. In contrast, we observed robust, Dectin-l-dependent IL-22 production by unfractionated lung digest cells. Intriguingly, the absence of IL-22 alone mimicked the attenuated proallergic and proinflammatory responses observed in the absence of Dectin-1, suggesting that Dectin-l-mediated IL-22 production potentiated responses that led to decrements in lung function. To this end, neutralization of IL-22 improved lung function in normal mice. Collectively, these results indicate that the β-glucan receptor Dectin-1 contributes to lung inflammation and immunopathology associated with persistent fungal exposure via the production of IL-22. [ABSTRACT FROM AUTHOR]

The inhalation of airborne pollutants, such as asbestos or silica, is linked to inflammation of the lung, fibrosis, and lung cancer. How the presence of pathogenic dust is recognized and how chronic inflammatory diseases are triggered are poorly understood. Here, we show that asbestos and silica are sensed by the Nalp3 inflammasome, whose subsequent activation leads to interleukin-1β secretion. Inflammasome activation is triggered by reactive oxygen species, which are generated by a NADPH oxidase upon particle phagocytosis. (NADPH is the reduced form of nicotinamide adenine dinucleotide phosphate.) In a model of asbestos inhalation, Nalp3-/- mice showed diminished recruitment of inflammatory cells to the lungs, paralleled by lower cytokine production. Our findings implicate the Nalp3 inflammasome in particulate matter-related pulmonary diseases and support its role as a major proinflammatory "danger" receptor. [ABSTRACT FROM AUTHOR]

Abstract: Background: The role of Th1 and Th2 mediated cytokine responses in the pathogenesis of Cryptococcus neoformans infection in organ transplant recipients has not been defined. Methods: We assessed cytokine levels in the sera and CSF collected prospectively at the time of diagnosis of infection in 25 transplant recipients with cryptococcosis. Serum levels were compared with those in healthy individuals and transplant recipients without cryptococcosis. IFN-γ or IL-12 (Th1)/IL-10 (Th2) ratio <1.0 was considered a dominant Th2 response. Results: Cases had lower ratios of IFN-γ/IL-10 (p =0.03) and IL-12/IL-10 (p =0.03) compared to healthy individuals. Cytokine responses, however, did not differ significantly for cases vs. transplant controls. Cases with fungemia compared to those without fungemia tended to have higher serum IL-10 levels (p =0.07) and lower IL-12/IL-10 ratios (p =0.06). CSF ratios of IFN-γ/IL-10 (p =0.04) and IL-12/IL-10 (p =0.04) were lower in cases with cryptococcal meningitis compared to those without meningitis; 80% (8/10) of the cases with cryptococcal meningitis vs. 0% (4/4) of those without meningitis had CSF IFN-γ/IL-10 ratio of <1.0 (p =0.015). The levels of IL-10 (p =0.04) and IFN-γ (p =0.04) in the CSF in cases with cryptococcal meningitis were significantly higher than those in their serum, respectively. Conclusions: High expression of Th2 phenotype in cryptococcal meningitis and in fungemia suggests that Th dysregulation may contribute to the pathogenesis of cryptococcosis in organ transplant recipients. [Copyright &y& Elsevier]