Thrombin Induces Interleukin-8 (IL-8) and Monocyte Chemoattractant Protein-1 (MCP-1) in Alveolar Type II Cells

Abstract 1831 Neonatal Pulmonology II: Oxidant and Inflammatory Lung Injury Poster Symposium, Tuesday, 5/4

INTRODUCTION: Blood coagulation proteins form a significant component of hyaline membranes in HMD. One of these proteins, thrombin has been shown to induce inflammatory cytokine production in macrophages. Alveolar type II cells participate in lung inflammation by producing cytokines in response to a variety of stimuli. We examined the capability of Type II cells to produce IL-8 (the major neutrophil chemotactic chemokine) and MCP-1 (a major macrophage chemotactic chemokine) in response to thrombin. METHODS: Confluent A549 (1×10⁶ cells/well) were incubated in quadruplicate for 48 hours with increasing concentrations of thrombin. The media were assayed for IL-8, MCP-1, Interleukin-1 β (IL-1β), tumor necrosis factor-α (TNFα) and epithelial neutrophil chemoattractant protein-78 (ENA-78) by ELISA. Total RNA was extracted from the cell layer for RT-PCR. ANOVA was used to assess differences between treatment groups. RESULTS: Thrombin induced IL- and MCP-1 in A549 cells in a dose dependent manner. ENA-78 concentrations were not increased significantly with thrombin treatment. Treatment with thrombin did not induce production of either IL-1β or TNFα. CONCLUSIONS: These results suggest that thrombin may induce the production of IL-8 and MCP-1 in type II cells by a mechanism independent of IL-1β or TNFα. This may represent another mechanism for type II cell mediated inflammatory response in acute lung injury. (Figure)

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