Abstract

Listeria monocytogenes (LM) infection induces pyroptosis, a form of regulated necrosis, in host macrophages via inflammasome activation. Here, we examined the role of Mint3 in macrophages, which promotes glycolysis via hypoxia-inducible factor-1 activation, during the initiation of pyroptosis following LM infection. Our results showed that Mint3-deficient mice were more resistant to lethal listeriosis than wild-type (WT) mice. Additionally, the mutant mice showed higher levels of IL-1β/IL-18 in the peritoneal fluid during LM infection than WT mice. Moreover, ablation of Mint3 markedly increased the activation of caspase-1, maturation of gasdermin D, and pyroptosis in macrophages infected with LM in vitro, suggesting that Mint3 depletion promotes pyroptosis. Further analyses revealed that Mint3 depletion upregulates inflammasome assembly preceding pyroptosis via glycolysis reduction and reactive oxygen species production. Pharmacological inhibition of glycolysis conferred resistance to listeriosis in a Mint3-dependent manner. Moreover, Mint3-deficient mice treated with the caspase-1 inhibitor VX-765 were as susceptible to LM infection as WT mice. Taken together, these results suggest that Mint3 depletion promotes pyroptosis in host macrophages, thereby preventing the spread of LM infection. Mint3 may serve as a target for treating severe listeriosis by inducing pyroptosis in LM-infected macrophages.

Highlights

  • Listeria monocytogenes (LM) is a Gram-positive short rod that is highly abundant in the intestinal tracts of ruminants

  • At later time points (3 and 7 days after LM infection), there was no significant difference in bacterial counts between the strains (Fig. 1B, C)

  • Since Mint[3] depletion rapidly activated the inflammasome and induced pyroptosis of LM-infected macrophages, we investigated whether inhibition of caspase-1 early during LM infection altered resistance to LM infection

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Summary

Introduction

Listeria monocytogenes (LM) is a Gram-positive short rod that is highly abundant in the intestinal tracts of ruminants. LM causes listeriosis, which is zoonotically transmitted through contaminated food such as dairy products. Bacteremia arising from the intestinal tract and the liver can infect the fetus and cause meningitis. Listeriosis is frequently observed in LM serves as an excellent model of an intracellular parasite for immunology-related studies[3,4]. Upon internalization into host cells, LM escapes from the primary phagosomes and proliferates in the cytoplasm, where it evades host immunity by expressing various pathogenic factors represented by listeriolysin O (LLO). Interferon-γ (IFN-γ) produced by Th1 cells activates macrophages, and LM remaining in the cytoplasm is killed by the action of reactive oxygen species (ROS) and nitric oxide (NO)[5]

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