Background: Idiopathic pulmonary fibrosis (IPF) is a common, progressive and invariably lethal interstitial lung disease with no effective therapy. We hypothesised that K Ca 3.1 K

We have investigated the possibility that nitric oxide (NO) synthesis may affect the course of a trypanosome infection via T-cell responses using mice deficient in inducible NO synthase (iNOS). Parasitemia levels increased at the same rate in both iNOS-deficient homozygous and control heterozygous mice, and peak parasitemia values were the same in both groups. However, the heterozygous mice maintained higher parasitemia levels after the peak of an infection than the homozygous mice due to a decrease in the rate of clearance of parasites. In iNOS-deficient mice there was an increase in the numbers of total CD4+ cells and activated (interleukin-2 receptor-expressing) CD4+ cells in infected mice compared with the numbers in uninfected mice. Spleen cells from infected iNOS-deficient mice displayed increased proliferative responses and gamma interferon secretion when stimulated in vitro than those of control mice. These data suggest that NO production depresses T-helper 1-like responses generated during Trypanosoma brucei infections, thus promoting the survival of the parasite.

Introduction and objectives IL-33 is a 31KDa cytokine which is a member of the IL-1 family. It resides in the nucleus of endothelial and epithelial cells as a chromatin-associated factor in vivo. IL-33 is thought to be released from stressed or necrotic, but not apoptotic, endothelial or epithelial cells in response to cell injury or infection, acting as an endogenous 'alarmin', to alert the immune system of cell and tissue damage. IL-33 is then able to bind to its receptor (ST2) on immune cells, thereby stimulating immunoregulatory activity through induction of NF-kB and mitogen-activated protein kinases, as well as enhancing the production of the Th2 cytokines IL-5 and IL-13. There is increasing evidence that IL-33 may have a protective role in terms of endothelial integrity and function. As the pathogenesis of pulmonary arterial hypertension (PAH) is thought to involve endothelial cell dysfunction, we were interested to see whether there may be a role for IL-33 in this condition. Methods RT-PCR for IL-33 was performed on human pulmonary arterial cells (HPAECs) derived from normal healthy controls and patients with idiopathic PAH. siRNA IL-33 knockdown was performed using smartpool duplexes on normal HPAECs. RT-PCR was then performed using QuantiTec primer assays. Results IL-33 mRNA expression was decreased 2.1-fold in PAH patient samples (0.36960.02, n¼10) compared to controls (0.76160.06, n¼14) p<0.005. In normal human lung tissue, intense IL-33 staining was shown in the ECs nuclear in blood vessels. It is also worth to note that there was little or no IL-33 staining in nonECs. siRNA knockdown IL-33 in HPAECs resulted in a 1.860.22, 1.360.13 and 1.460.20 (n¼3) fold increase of mRNA IL-6, BMP-9 and ST2 mRNA, respectively; whereas RANTES, fractalkine and cathepsin-L mRNA was decreased by 1.560.03, 1.760.01 and 2.160.17 fold respectively (n¼3) (Abstract S154 Figure 1). Conclusion IL-33mayplay an important role in the pathogenesis of PAH through regulating the expression ofcytokines and chemokines known to be involved in vascular remodelling. In particular, it is of interest that Il-33 may regulate IL-6 production and ST2 which acts as an endogenous IL-33 inhibitor. Background Pulmonary arterial hypertension (PAH) is a fatal condition involving remodelling of the pulmonary vessel wall leading to elevated pulmonary arterial pressure and eventually right heart failure. ST2 is a transmembrane receptor with ligand interleukin-33 (IL-33). p38 MAP kinase is an intracellular signalling molecule shown to be involved in the vascular remodelling associated with PAH; and is also involved in ST2/IL-33 signalling. ST2/ IL-33 signalling has been shown to reduce fibrosis in the heart following pressure overload in animal models. Aims To determine whether ST2/IL-33 signalling was involved in the proliferation of mouse pulmonary artery fibroblasts and if p38 MAP kinase was involved. Methods Two cell types were useddwild type (WT) and ST2 knockout (ST2À/À) mouse pulmonary artery fibroblasts. Proliferation was assessed by [

Methods Using an in vitro wound repair model we explored the interaction of human Clara cells (H441 cell line) and type II AEC (A549 cell line). A transwell co-culture system was developed to determine the direct contact effect of densely populated Clara cells on wounded AEC monolayers. Results In serum-free media, lone H441 cell wound repair was higher than equivalent A549 cells, despite the fourfold slower doubling time of H441 cells. Serum-free conditioned media obtained from unwounded and wounded H441 monolayers did not show any significant influence on A549 wound repair. However, in a direct contact coculture A549-H441 cell model significant inhibition of A549 wound repair (p<0.005) was observed. Interestingly, H441 migration into the injured A549 layer was seen after 24 h; with a significant proportion of migrated H441 cells found at the wound margins. Coupled to this migration we observed a 50% reduction in A549 cell number at the wound margins. TUNEL assay detected about 40% A549 apoptosis in juxta-wound monolayers in A549-H441 direct contact (p<0.00001). This direct contact-induced apoptosis was significantly blocked by TRAIL-R1 and R2 combined receptor blockers (p<0.00001); whereas, Fas blocker failed to block this apoptosis. Conclusion In summary, direct contact of H441 cells induces apoptosis in the A549 monolayers through a TRAIL-dependent mechanism which disrupts wound margin integrity, inhibiting wound repair. This novel observation warrants further exploration of the role of Clara cell-alveolar epithelial cell interaction within the context of aberrant wound repair associated with chronic fibrotic lung disorders.

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