» Articles » PMID: 38740925

GITR Exacerbates Lysophosphatidylcholine-induced Macrophage Pyroptosis in Sepsis Via Posttranslational Regulation of NLRP3

Overview
Date 2024 May 13
PMID 38740925
Authors
Affiliations
Soon will be listed here.
Abstract

The NLRP3 inflammasome functions as an inflammatory driver, but its relationship with lipid metabolic changes in early sepsis remains unclear. Here, we found that GITR expression in monocytes/macrophages was induced by lysophosphatidylcholine (LPC) and was positively correlated with the severity of sepsis. GITR is a costimulatory molecule that is mainly expressed on T cells, but its function in macrophages is largely unknown. Our in vitro data showed that GITR enhanced LPC uptake by macrophages and specifically enhanced NLRP3 inflammasome-mediated macrophage pyroptosis. Furthermore, in vivo studies using either cecal ligation and puncture (CLP) or LPS-induced sepsis models demonstrated that LPC exacerbated sepsis severity/lethality, while conditional knockout of GITR in myeloid cells or NLRP3/caspase-1/IL-1β deficiency attenuated sepsis severity/lethality. Mechanistically, GITR specifically enhanced inflammasome activation by regulating the posttranslational modification (PTM) of NLRP3. GITR competes with NLRP3 for binding to the E3 ligase MARCH7 and recruits MARCH7 to induce deacetylase SIRT2 degradation, leading to decreasing ubiquitination but increasing acetylation of NLRP3. Overall, these findings revealed a novel role of macrophage-derived GITR in regulating the PTM of NLRP3 and systemic inflammatory injury, suggesting that GITR may be a potential therapeutic target for sepsis and other inflammatory diseases. GITR exacerbates LPC-induced macrophage pyroptosis in sepsis via posttranslational regulation of NLRP3. According to the model, LPC levels increase during the early stage of sepsis, inducing GITR expression on macrophages. GITR not only competes with NLRP3 for binding to the E3 ligase MARCH7 but also recruits MARCH7 to induce the degradation of the deacetylase SIRT2, leading to decreasing ubiquitination but increasing acetylation of NLRP3 and therefore exacerbating LPC-induced NLRP3 inflammasome activation, macrophage pyroptosis and systemic inflammatory injury.

Citing Articles

Pyroptosis and sepsis-associated acute kidney injury.

Xiao C, Li X Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2025; 49(8):1333-1340.

PMID: 39788522 PMC: 11628236. DOI: 10.11817/j.issn.1672-7347.2024.240233.

References
1.
Singer M, Deutschman C, Seymour C, Shankar-Hari M, Annane D, Bauer M . The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016; 315(8):801-10. PMC: 4968574. DOI: 10.1001/jama.2016.0287. View

2.
van der Poll T, van de Veerdonk F, Scicluna B, Netea M . The immunopathology of sepsis and potential therapeutic targets. Nat Rev Immunol. 2017; 17(7):407-420. DOI: 10.1038/nri.2017.36. View

3.
Samra J, Summers L, Frayn K . Sepsis and fat metabolism. Br J Surg. 1996; 83(9):1186-96. PMC: 11440814. View

4.
Rathinam V, Fitzgerald K . Inflammasome Complexes: Emerging Mechanisms and Effector Functions. Cell. 2016; 165(4):792-800. PMC: 5503689. DOI: 10.1016/j.cell.2016.03.046. View

5.
Mangan M, Olhava E, Roush W, Seidel H, Glick G, Latz E . Targeting the NLRP3 inflammasome in inflammatory diseases. Nat Rev Drug Discov. 2018; 17(8):588-606. DOI: 10.1038/nrd.2018.97. View