Abstract: Objective To investigate the role of Annexin 1 (ANXA1) on inflammatory response and cell apoptosis induced by BCG in a macrophage cell line RAW264.7. Methods The RAW264.7 cells infected by BCG were established. RT-PCR was performed to detect the mRNA expression of ANXA1, IL-6 and TNF-α. The protein expression of ANXA1, Bcl-2, Bax and Caspase-3 were analyzed by Western blot assays. The expression level of inflammatory cytokines IL-6 and TNF-α were measured using ELISA analysis. Cell viability was assayed by MTT assay. ELISA assay was used to determine the cell apoptosis. Results The expression level of ANXA1 was downregulated in a time-dependent manner in RAW264.7 infected with BCG. Additionally, overexpression of ANXA1 notably downregulated the production of pro-inflammatory cytokines IL-6 and TNF-α induced by BCG infection. Moreover, overexpression of ANXA1 remarkably elevated the cell viability, and suppressed BCG-induced macrophage apoptosis as reflected by increasing the level of anti-apoptotic Bcl-2 and decreasing expression of the pro-apoptotic protein Bax, accompanied by the downregulation of Caspase-3 expression in RAW264.7 in response to BCG. Conclusion ANXA1 modulated the innate host defense by suppressing inflammatory response and cell apoptosis against M.tb infection, which may provide a promising therapeutic target for tuberculosis.

Key words: Annexin 1 (ANXA1), Inflammatory response, Cell apoptosis, Mycobacterium tuberculosis (M.tb)