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Background: Pulmonary fibrosis is a frequent complication and a major cause of death in Systemic sclerosis (SSc); however, the pathogenesis is unclear and no safe and effective therapy exists The abnormal collagen deposition and the autoantibodies observed are significant important in this situation, in the last years we postulate that the pathogenetic mechanisms of the tissue fibrosis en SSc is mediate by collagen V alteration. Methods: We examined the amount of collagen V and mRNA chains expression using immunofluorescence, Real−time PCR and computer morphometric analysis in 15 open lung biopsies of patients with SSc without pulmonary hypertension. Normal lung tissue was obtained from 8 individuals who had died from traumatic injuries, as a control group. The pulmonary function tests were analyzed in theses cases and correlated with collagen amount and PCR chains expression. Results: The amount of collagen type V (45.28±13.21) in pulmonary interstitum was significance higher when compared with control (22.90±4.13) group (p<0.001). In SSc we found increase in both, alpha 1 (1.32±0.34) and 2 (0.86±0.19) chains mRNA expression when compared with alpha 1 (0.50±0.10) and 2 (0.11±0.05) chains of control group, being the proportion between alpha 1 and 2 chains of 2:1 in the control group not maintained in SSc. In fact, alfa 2 chain was more increased in SSc. Interestingly, a significant inverse association was found between collagen V VC (rs = −0.72; p=0.002), FCV (rs = −0.76; p<0.001) and FEV1 (rs = −0.89; p<0.001) pulmonary function tests. Conclusions: We concluded that pulmonary fibrosis in SSc probably occurs by abnormal collagen V chains mRNA synthesis reinforcing the participation of this collagen in pathogenesis of SSc and open new therapeutic perspectives for these patients. This abstract is funded by: FAPESP, CNPq. Am J Respir Crit Care Med 179;2009:A3942 Internet address: www.atsjournals.org Online Abstracts Issue

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