Abstract:

Objective To investigate the mechanisms of phagocytosis of virulent Leptospira by peritoneal macrophages of guinea pigs, and evaluate the role of innate immune in the pathogenesis of leptospirosis. Methods Peritoneal macrophages of guinea pigs were extracted. Three specific inhibitors (microfilament inhibitor cytochalasin D, microtube inhibitor colchicine and PI3K signalling pathway inhibitor LY294002) were added respectively to the macrophages 1 h before the infection of virulent Leptospira interrogans serovar Lai type strain Lai in vitro. Meanwhile, control group without inhibitor was established. Phagocytosis was observed by laser scanning confocal microscopy and phagocytic rates were evaluated by flow cytometry 3 h after infection. Results The phagocytic rates of control group, cytochalasin D group, colchicine group and LY294002 group were (38.98±0.91)%, (23.99±1.40)%, (40.81±0.91)%, and (39.64±3.56)%, respectively. The phagocytic rate of cytochalasin D group was significantly lower than that of control group (P<0.05), while those of colchicine group and LY294002 group were not significantly different from that of control group (P>0.05). Conclusion Microfilaments play an important role in the phagocytosis of strain Lai by peritoneal macrophages, but the process is independent on PI3K signalling pathway, and microtubes play little part during the phagocytosis.

Key words: microtube, microfilament, PI3K, peritoneal macrophage, Leptospira