Abstract: Objective  To explore the effects of different components of Edwardsiella tarda on pulmonary inflammatory responses and to clarify the potential role of Edwardsiella tarda in progression of chronic obstructive pulmonary disease(COPD), which might provide a novel theoretical basis for the pathogenesis of COPD.  Methods  In vivo, mice were given different components derived from Edwardsiella tarda (inactivated bodies, bacterial lysates and supernatant of cultured bacteria) intranasally to establish mice models of acute lung injury. Inflammatory cells in bronchoalveolar lavage fluid (BALF) were analyzed by cell differential counting on stained smears; enzyme-linked immunosorbent assay (ELISA)was used to measure the concentrations of proinflammatory cytokines in BALF; Histochemical and immunohistochemical staining were individually employed to detect eosinophils and IL-33+ cells in lung tissue. In vitro, different components derived from Edwardsiella tarda were used to stimulate pulmonary epithelial cells and macrophages, and concentrations of proinflammatory cytokines in the cell culture supernatant were also measured by ELISA. Results  The bacterial lysates and metabolites of Edwardsiella tarda significantly increased the number of neutrophils and macrophages and the levels of the pro-inflammatory cytokines IL-1β, IL-6 and tumor necrosis factor α (TNF-α) in BALF; inactivated bacteria induced more eosinophils and IL-33⁺ cells infiltration in lung tissue. The different components of Edwardsiella tarda also stimulated production of proinflammatory cytokines by human and murine pulmonary epithelial cells and macrophages. Conclusion  Edwardsiella tarda can cause pulmonary inflammatory response, possibly through inducing inflammatory cytokines by epithelial cells and macrophages.

Key words: Edwardsiella tarda, chronic obstructive pulmonary disease, inflammation, respiratory tract