Legionella pneumophila induces human beta Defensin-3 in pulmonary cells

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>is an important causative agent of severe pneumonia in humans. Human alveolar epithelium and macrophages are effective barriers for inhaled microorganisms and actively participate in the initiation of innate host defense. The beta defensin-3 (hBD-3), an antimicrobial peptide is an important component of the innate immune response of the human lung. Therefore we hypothesize that hBD-3 might be important for immune defense towards <it>L. pneumophila</it>.</p> <p>Methods</p> <p>We investigated the effects of <it>L. pneumophila </it>and different TLR agonists on pulmonary cells in regard to hBD-3 expression by ELISA. Furthermore, siRNA-mediated inhibition of TLRs as well as chemical inhibition of potential downstream signaling molecules was used for functional analysis.</p> <p>Results</p> <p><it>L. pneumophila </it>induced release of hBD-3 in pulmonary epithelium and alveolar macrophages. A similar response was observed when epithelial cells were treated with different TLR agonists. Inhibition of TLR2, TLR5, and TLR9 expression led to a decreased hBD-3 expression. Furthermore expression of hBD-3 was mediated through a JNK dependent activation of AP-1 (c-Jun) but appeared to be independent of NF-κB. Additionally, we demonstrate that hBD-3 elicited a strong antimicrobial effect on <it>L. pneumophila </it>replication.</p> <p>Conclusions</p> <p>Taken together, human pulmonary cells produce hBD-3 upon <it>L. pneumophila </it>infection via a TLR-JNK-AP-1-dependent pathway which may contribute to an efficient innate immune defense.</p

Sputum and nasal lavage lung-specific biomarkers before and after smoking cessation

<p>Abstract</p> <p>Background</p> <p>Little is known about the effect of smoking cessation on airway inflammation. Secretory Leukocyte Protease Inhibitor (SLPI), Clara Cell protein 16 (CC16), elafin and human defensin beta-2 (HBD-2) protect human airways against inflammation and oxidative stress. In this longitudinal study we aimed to investigate changes in sputum and nasal lavage SLPI, CC16, elafin and HBD-2 levels in healthy smokers after 6 and 12 months of smoking cessation.</p> <p>Methods</p> <p>Induced sputum and nasal lavage was obtained from healthy current smokers (n = 76) before smoking cessation, after 6 months of smoking cessation (n = 29), after 1 year of smoking cessation (n = 22) and from 10 healthy never smokers. SLPI, CC16, elafin and HBD-2 levels were measured in sputum and nasal lavage supernatants by commercially available ELISA kits.</p> <p>Results</p> <p>Sputum SLPI and CC-16 levels were increased in healthy smokers before smoking cessation versus never-smokers (p = 0.005 and p = 0.08 respectively). SLPI and CC16 levels did not differ before and 6 months after smoking cessation (p = 0.118 and p = 0.543 respectively), neither before and 1 year after smoking cessation (p = 0.363 and p = 0.470 respectively). Nasal lavage SLPI was decreased 12 months after smoking cessation (p = 0.033). Nasal lavage elafin levels were increased in healthy smokers before smoking cessation versus never-smokers (p = 0.007), but there were no changes 6 months and 1 year after smoking cessation.</p> <p>Conclusions</p> <p>Only nasal lavage SLPI decrease after 1 year after smoking cessation. We may speculate that there is an ongoing inflammatory process stimulating the production of counter-regulating proteins in the airways of healthy ex-smokers.</p

A Novel Role for the NLRC4 Inflammasome in Mucosal Defenses against the Fungal Pathogen Candida albicans

Candida sp. are opportunistic fungal pathogens that colonize the skin and oral cavity and, when overgrown under permissive conditions, cause inflammation and disease. Previously, we identified a central role for the NLRP3 inflammasome in regulating IL-1β production and resistance to dissemination from oral infection with Candida albicans. Here we show that mucosal expression of NLRP3 and NLRC4 is induced by Candida infection, and up-regulation of these molecules is impaired in NLRP3 and NLRC4 deficient mice. Additionally, we reveal a role for the NLRC4 inflammasome in anti-fungal defenses. NLRC4 is important for control of mucosal Candida infection and impacts inflammatory cell recruitment to infected tissues, as well as protects against systemic dissemination of infection. Deficiency in either NLRC4 or NLRP3 results in severely attenuated pro-inflammatory and antimicrobial peptide responses in the oral cavity. Using bone marrow chimeric mouse models, we show that, in contrast to NLRP3 which limits the severity of infection when present in either the hematopoietic or stromal compartments, NLRC4 plays an important role in limiting mucosal candidiasis when functioning at the level of the mucosal stroma. Collectively, these studies reveal the tissue specific roles of the NLRP3 and NLRC4 inflammasome in innate immune responses against mucosal Candida infection

The ΔF508 mutation causes CFTR misprocessing and cystic fibrosis-like disease in pigs

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. The most common CF-associated mutation is ΔF508, which deletes a phenylalanine in position 508. In vitro studies indicate that the resultant protein, CFTR-ΔF508, is misprocessed, although the in vivo consequences of this mutation remain uncertain. To better understand the effects of the ΔF508 mutation in vivo, we produced CFTR ΔF508/ΔF508 pigs. Our biochemical, immunocytochemical, and electrophysiological data on CFTR-ΔF508 in newborn pigs paralleled in vitro predictions. They also indicated that CFTR ΔF508/ΔF508 airway epithelia retain a small residual CFTR conductance, with maximal stimulation producing ∼6% of wild-type function. Cyclic adenosine 3′,5′-monophosphate (cAMP) agonists were less potent at stimulating current in CFTR ΔF508/ΔF508 epithelia, suggesting that quantitative tests of maximal anion current may overestimate transport under physiological conditions. Despite residual CFTR function, four older CFTR ΔF508/ΔF508 pigs developed lung disease similar to human CF. These results suggest that this limited CFTR activity is insufficient to prevent lung or gastrointestinal disease in CF pigs. These data also suggest that studies of recombinant CFTR-ΔF508 misprocessing predict in vivo behavior, which validates its use in biochemical and drug discovery experiments. These findings help elucidate the molecular pathogenesis of the common CF mutation and will guide strategies for developing new therapeutics.link_to_subscribed_fulltex