Endothelial SOCS3 maintains homeostasis and promotes survival in endotoxemic mice

• Published in: JCI insight Vol. 6; no. 14
• Main Authors: Martino, Nina, Ramos, Ramon Bossardi, Lu, Shuhan, Leyden, Kara, Tomaszek, Lindsay, Sadhu, Sudeshna, Fredman, Gabrielle, Jaitovich, Ariel, Vincent, Peter A, Adam, Alejandro P
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 22.07.2021; American Society for Clinical investigation
• Subjects: Animals; Disease Models, Animal; Endothelium, Vascular - pathology; Endotoxemia - diagnosis; Endotoxemia - immunology; Endotoxemia - mortality; Endotoxemia - pathology; Heterozygote; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Interleukin-6 - metabolism; Lipopolysaccharides - administration & dosage; Lipopolysaccharides - immunology; Mice; Mice, Knockout; Proteolysis; Severity of Illness Index; Suppressor of Cytokine Signaling 3 Protein - analysis; Suppressor of Cytokine Signaling 3 Protein - genetics; Suppressor of Cytokine Signaling 3 Protein - metabolism; Ubiquitination; Vascular biology; Signal transduction; Inflammation; Cytokines; Vascular Biology; Endothelial cells
• ISSN: 2379-3708; 2379-3708
• DOI: 10.1172/jci.insight.147280

SOCS3 is the main inhibitor of the JAK/STAT3 pathway. This pathway is activated by interleukin 6 (IL-6), a major mediator of the cytokine storm during shock. To determine its role in the vascular response to shock, we challenged mice lacking SOCS3 in the adult endothelium (SOCS3iEKO) with a nonlethal dose of lipopolysaccharide (LPS). SOCS3iEKO mice died 16-24 hours postinjection after severe kidney failure. Loss of SOCS3 led to an LPS-induced type I IFN-like program and high expression of prothrombotic and proadhesive genes. Consistently, we observed intraluminal leukocyte adhesion and neutrophil extracellular trap-osis (NETosis), as well as retinal venular leukoembolization. Notably, heterozygous mice displayed an intermediate phenotype, suggesting a gene dose effect. In vitro studies were performed to study the role of SOCS3 protein levels in the regulation of the inflammatory response. In human umbilical vein endothelial cells, pulse-chase experiments showed that SOCS3 protein had a half-life less than 20 minutes. Inhibition of SOCS3 ubiquitination and proteasomal degradation led to protein accumulation and a stronger inhibition of IL-6 signaling and barrier function loss. Together, our data demonstrate that the regulation of SOCS3 protein levels is critical to inhibit IL-6-mediated endotheliopathy during shock and provide a promising therapeutic avenue to prevent multiorgan dysfunction through stabilization of endothelial SOCS3.