Gut Microbial Metabolite Butyrate Alleviates the Susceptibility to Septic DIC By Suppressing Caspase-11/ Gsdmd-Dependent Macrophage Pyroptosis

Introduction: Disseminated intravascular coagulation (DIC), a prevalent complication of sepsis, is a significant contributor to multiple organ dysfunction syndrome (MODS) and mortality in septic patients. The intestine has been considered as the motor of MODS in sepsis. We identified a disparate predisposition to DIC in septic mice, which we categorized into two groups—DIC-resistant (Res) and DIC-sensitive (Sen) mice. However, the mechanism behind this phenomenon remains unclear.

Methods: Cecal ligation and puncture (CLP) was used to induce septic DIC. Feces were collected before CLP to detect intestinal flora composition by 16S rRNA and short-chain fatty acids by targeted metabolome. Fecal microbiota transplantation was performed to study the role of gut microbiota and its metabolites in susceptibility to septic DIC. Macrophage pyroptosis were comprehensively assessed by morphology, levels of IL-1β and lactate dehydrogenase (LDH) in plasma and supernatants. The Western blotting was used to confirmed pyroptosis at the molecular level.

Results: The Sen mice were more likely to develop DIC and multiple organ failure than Res mice. The relative abundance of butyric-producing bacteria, Firmicutes and the concentration of butyrate in Res mice were significantly higher compared to the Sen mice. Intriguingly, the susceptibility to septic DIC could be transmitted via the intestinal microbiota. Meanwhile, butyrate can effectively reduce the mortality of DIC, concurrently alleviating coagulopathy and mitigating MODS. Mechanistically, the proportion of peritoneal macrophage pyroptosis, plasma levels of IL-1β and LDH in Sen mice were statistically higher than that in Res mice, and butyrate could reduce these indicators and downregulate the expression of histone deacetylase 3 (HDAC3). For LPS-transfected bone marrow derived macrophages (BMDMs), sodium butyrate (NaB), HDAC3 inhibitor, caspase-11 inhibitor, and GSDMD inhibitor could improve the changes of morphology, which was manifested by diminished cellular antennae, augmented swelling, and the presence of distinct pyroptosis vesicles. In addition, the release of IL-1β was significantly reduced by NaB and inhibitors above, compared to LPS-transfected BMDMs. Under LPS-transfected condition, NaB could impeded HDAC3 expression compared to the control and HDAC3 inhibitor groups. Moreover, NaB and HDAC3 inhibitor effectively inhibited the cleavage of caspase-11 and GSDMD.

Conclusion: Butyrate, a metabolite of enteric Firmicutes, exerts a suppressive influence on the activation of the caspase-11/GSDMD pathway in macrophages by modulating the activity of HDAC3, subsequently impeding the onset and progression of DIC in sepsis, providing a novel theoretical basis for targeted intervention in sepsis and DIC.