Rv2647-Mediated NLRP3 Ubiquitination Inhibits Macrophage Pyroptosis and Promotes Mycobacterium tuberculosis Survival.

Inflammasome-mediated pyroptosis and cytokine release are crucial host defenses against intracellular pathogens. Mycobacterium tuberculosis (M. tb) is a successful intracellular pathogen, and it is largely unclear how it evades immune clearance and persists in macrophages. This study investigated whether the Rv2647 protein acts as a key virulence factor of M. tb and explored the potential mechanism of inhibiting macrophage pyroptosis and promoting M. tb survival. The results showed Rv2647 promoted NLRP3 degradation via enhancing its ubiquitination, which led to the inactivation of NLRP3/caspase-1/GSDMD and reduction of IL-1β secretion, thereby inhibiting macrophage pyroptosis and facilitating M. tb survival. Furthermore, Rv2647-mediated enhancement of NLRP3 ubiquitination and degradation depended on its binding to ISG15, competitively inhibiting ISGylation of NLRP3. The study identified Rv2647 as the key virulence factor that promoted M. tb survival by inhibiting macrophage pyroptosis, whose mechanism was to competitively inhibit the ISGylation of NLRP3 and enhance its ubiquitination, thus suppressing NLRP3/caspase-1/GSDMD-mediated pyroptosis. This finding highlighted Rv2647 as a promising drug target or vaccine antigen for tuberculosis prevention and control.