Open AccessMycobacterium tuberculosis protein ESAT‐6 is a potent activator of the NLRP3/ASC inflammasome
Author(s) -
Mishra Bibhuti B.,
MouraAlves Pedro,
Sonawane Avinash,
Hacohen Nir,
Griffiths Gareth,
Moita Luis F.,
Anes Elsa
Publication year - 2010
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2010.01450.x
Subject(s) - inflammasome , secretion , biology , esat 6 , aim2 , caspase 1 , microbiology and biotechnology , mycobacterium tuberculosis , activator (genetics) , inflammation , receptor , immunology , tuberculosis , bacteria , bacterial protein , medicine , biochemistry , genetics , pathology
Summary Interleukin‐1β (IL‐1β) represents one of the most important mediators of inflammation and host responses to infection. Mycobacterium tuberculosis (Mtb) , the causative agent of human tuberculosis, induces IL‐1β secretion at the site of infection, but the underlying mechanism(s) are poorly understood. In this work we show that Mtb infection of macrophages stimulates caspase‐1 activity and promotes the secretion of IL‐1β. This stimulation requires live intracellular bacteria expressing a functional ESX‐1 secretion system. ESAT‐6, an ESX‐1 substrate implicated in membrane damage, is both necessary and sufficient for caspase‐1 activation and IL‐1β secretion. ESAT‐6 promotes the access of other immunostimulatory agents such as AG85 into the macrophage cytosol, indicating that this protein may contribute to caspase‐1 activation largely by perturbing host cell membranes. Using a high‐throughput shRNA‐based screen we found that numerous NOD‐like receptors (NLRs) and CARD domain‐containing proteins (CARDs) were important for IL‐1β secretion upon Mtb infection. Most importantly, NLRP3, ASC and caspase‐1 form an infection‐inducible inflammasome complex that is essential for IL‐1β secretion. In summary, we show that recognition of Mtb infection by the NLRP3 inflammasome requires the activity of the bacterial virulence factor ESAT‐6, and the subsequent IL‐1β response is regulated by a number of NLR/CARD proteins.