Find in Library

Brucella utilizes diverse virulence factors to modulate the infectious cycle and lifestyle associated with eukaryotic hosts. Lipopolysaccharides (LPS) play an important role in the establishment of persistent infections of Brucella, but its mechanism in host cell to interfere with the host"s specific signaling pathway related to the elimination of Brucella is still not clear. LpsA, a glycosyl transferase, involves in the biosynthesis of LPS, and may aff ect the intracellular survival of Brucella. This study aimed to investigate the eff ects of lpsA on pyroptosis in Brucella-infected macrophage cells. We constructed the lpsA mutant strain (M5-90ΔlpsA) and the complementary strain (M5-90ΔlpsA-C) of Brucella melitensis strain M5-90 infected mouse macrophages to detect pyroptosis. We found that the inactivation of the lpsA gene weakened the ability of LPS gains access to cytosol during Brucella mutant infections, and reduced the survival of Brucella. Western blot and quantitative real-time PCR assays showed that the mRNA and protein levels of caspase-11 and NOD-like receptor family pyrin domain-containing 3 in M5-90ΔlpsA group were higher than those observed in M5-90 group. These results indicated M5-90ΔlpsA promoted the pyroptosis of RAW264.7 cells (a mouse macrophage cell line) after Brucella infection. The finding reveals that Brucella lpsA plays a partial role in innate immunity and infl ammatory response by inhibiting the LPS-induced atypical pyroptosis pathway.