[The OmpA-like protein Loa22 from Leptospira interrogans serovar lai induces apoptosis in A549 via Ca2+ signal pathway].

Objective To study the effect of Loa22 mature peptide on the apoptosis of A549 to explore the mechanism of pulmonary impairment in severe forms of leptospirosis.Methods Loa22 mature peptide(100 μg/mL) was administered to culture with human lung adenocarcinoma cell line(A549).After 24 hours,the apoptosis,the concentration of calcium of the cells were evaluated.The F-actin cytoskeleton structure was observed and calmdulin(CaM) mRNA expression was also detected.At the same time,after the pretreatment of A549 with PLC specific inhibitor U73122,adding an appropriate amount of mature peptide of Loa22 to act on the cells for a period of time,then detection same index.Results Loa22 mature peptide could induce the increase of intracellular Ca2+ concentration(i),CaM expression in mRNA level,the activity of LDH,and cytoskeleton rearrangement of F-actin.But after blocking the signal pathway of PLC,Loa22 mature peptide reduced the increase degree of i,apoptosis rate,the expression of CaM mRNA,the activity of LDH compared with the unblocked group.Conclusion These data suggest that Loa22 mature peptide involves in the pathological processes of L.interrogans invasion and increase apoptosis in A549 by increase of i through signaling pathway of PLC.