Identification of an ASC oligomerization inhibitor for the treatment of inflammatory diseases

Paula M Soriano-Teruel,María J Vicent,María Marco-Salvador,Mónica Sancho,Mar Orzáez,Guillermo García‑Laínez,Irmgard Merfort,Pablo Pelegrín,Maykel Arias,Christian Deford,Julián Pardo

doi:10.1038/s41419-021-04420-1

Abstract

The ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD)) protein is an scaffold component of different inflammasomes, intracellular multiprotein platforms of the innate immune system that are activated in response to pathogens or intracellular damage. The formation of ASC specks, initiated by different inflammasome receptors, promotes the recruitment and activation of procaspase-1, thereby triggering pyroptotic inflammatory cell death and pro-inflammatory cytokine release. Here we describe MM01 as the first-in-class small-molecule inhibitor of ASC that interferes with ASC speck formation. MM01 inhibition of ASC oligomerization prevents activation of procaspase-1 in vitro and inhibits the activation of different ASC-dependent inflammasomes in cell lines and primary cultures. Furthermore, MM01 inhibits inflammation in vivo in a mouse model of inflammasome-induced peritonitis. Overall, we highlight MM01 as a novel broad-spectrum inflammasome inhibitor for the potential treatment of multifactorial diseases involving the dysregulation of multiple inflammasomes.

Highlights

ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD)) is a protein of the innate immune system that participates in the formation of inflammasomes, which are macromolecular complexes responsible for the maturation and release of pro-inflammatory cytokines [1]
We demonstrate that MM01 disrupts ASC oligomerization triggered by different inflammasomes and inhibits downstream IL-1β/IL-18 release and pyroptosis in various cellular models of inflammation
MM01 blocks ASC-mediated pro-Casp-1 activation in vitro To identify inhibitors of ASC oligomerization, we first screened for molecules that inhibited the activation of pro-Casp-1 by ASC in an in vitro assay using recombinant human ASC purified from Escherichia coli and pro-Casp-1 purified from Baculovirus (Fig. S1A)

Summary

Introduction

ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD)) is a protein of the innate immune system that participates in the formation of inflammasomes, which are macromolecular complexes responsible for the maturation and release of pro-inflammatory cytokines [1]. NLR oligomerization promotes ASC binding and oligomerization in large filaments that aggregate into large structures known as ASC specks, thereby generating a multitude of pro-Casp-1 interaction sites that promotes the auto-processing and activation of pro-Casp-1 and, as a consequence, amplifying pro-inflammatory signaling [14, 15]. ASCCARD interacts with pro-Casp-1CARD to promote pro-Casp-1 oligomerization and activation and the subsequent processing and secretion of the mature forms of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18 [18]. The ASC dependence varies for each inflammasome, Received: 29 June 2021 Revised: 17 November 2021 Accepted: 23 November 2021

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