Expression of inflammatory cytokines and Fas in alveolar macrophages from ARDS patients

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The objective of this study was to evaluate the role of inducible nitric oxide synthase (iNOS) and proinflammatory cytokines together with apoptosis related factors in alveolar macrophages (AMs) in the pathogenesis of acute respiratory distress syndrome (ARDS) following sepsis. To investigate these expressions in AMs collected from ARDS patients following sepsis, the expression of iNOS and IL-1□,IL-6,IL-8 in AMs were determined by the immunofluorescent technique. The level of NOx, IL-1□,IL-6,and IL-8 in bronchoalveolar lavage fluid (BALF) supernatant and in serum were measured concurrently. To exclude the effect of the long-term ventilation, sepsis syndrome alone, and/or the administration of sedative drugs, all data obtained from patients with ARDS following sepsis were compared with the data from normal control subjects and from septic patients who had been mechanically ventilated for one week without fulfilling the criteria of ARDS (LTV group). Using immunofluorescent technique, our study identified the strong expression of iNOS in AMs of human lungs predominantly at the early stage of ARDS following sepsis. Whereas no expression of iNOS was observed in AMs from the control group, nor was observed in AMs from the LTV group. Another finding of this study is the marked increase of IL-6 and IL-8 levels in BALF supernatant and the serum from patients with ARDS as compared with the control and the LTV group. Also, statistically significant elevations were detected in NOx, IL-6 and IL-8 levels in BALF supernatant from the ARDS group compared with the control group. The result suggests that iNOS together with proinflammatory cytokines produced by AMs might play a pivotal role in the pathogenesis of acute lung injury and be useful for monitoring disorders in the lung of patients with ARDS following sepsis.