Necrosulfonamide inhibits pyroptosis through direct inhibition of gasdermin D.

Inflammasomes play essential roles in immune protection against microbial infections. However, excessive inflammation is implicated in various human diseases, including autoinflammatory syndromes, diabetes, multiple sclerosis, cardiovascular disorders and neurodegenerative diseases. Therefore, precise regulation of inflammasome activities is critical for adequate immune protection while limiting collateral tissue damage. In this review, we focus on the emerging roles of post-translational modifications (PTMs) that regulate activation of the NLRP3, NLRP1, NLRC4, AIM2 and IFI16 inflammasomes. We anticipate that these types of PTMs will be identified in other types of and less well-characterized inflammasomes. Because these highly diverse and versatile PTMs shape distinct inflammatory responses in response to infections and tissue damage, targeting the enzymes involved in these PTMs will undoubtedly offer opportunities for precise modulation of inflammasome activities under various pathophysiological conditions.

Significance: The inflammasomes are signaling platforms that promote the activation of inflammatory caspases such as caspases-1, -4, -5, and -11, which cleave gasdermin D (GSDMD) to induce pyroptotic cell death. The mechanisms of GSDMD recognition by inflammatory caspases remain poorly understood. Here, we demonstrate that the catalytic domains of inflammatory caspases can directly bind to GSDMD or its cleavage site peptide, FLTD. A GSDMD-derived inhibitor, N -acetyl-Phe-Leu-Thr-Asp-chloromethylketone (Ac-FLTD-CMK), inhibits GSDMD cleavage in vitro and suppresses pyroptosis downstream of both canonical and noncanonical inflammasomes. By contrast, the inhibitor does not target caspase-3 or apoptosis, suggesting that it is specific for inflammatory caspases. Structure of caspase-1 in complex with Ac-FLTD-CMK reveals extensive enzyme–inhibitor interactions that shed light on GSDMD recognition by inflammatory caspases.