Abstract 316: A Novel Mechanism by Which Tumor Necrosis Factor Alpha Protects Mice From Lipopolysaccharide-induced Vasodilatory Shock, Hypotension, and Motility

• Published in: Arteriosclerosis, thrombosis, and vascular biology Vol. 36; no. suppl_1
• Main Authors: Zhao, Guogang, Liu, Shu, Su, Wen, Song, Xiulong, Gong, Ming C, Guo, Zhenheng
• Format: Journal Article
• Language: English
• Published: 01.05.2016
• DOI: 10.1161/atvb.36.suppl_1.316
• ISSN: 1079-5642

Abstract only Objectives: Sepsis is defined by a severe systemic inflammatory response to infection, and its complications, including vasodilatory shock and hypotension, can be fatal. Vasodilatory shock has long been believed as a result of failure of the vascular smooth muscle cells (VSMCs) to respond to vasopressors to constrict and result in hypotension; however, the mechanism is largely unknown. Approaches and Results: Here, we report that protein kinase C (PKC)-potentiated phosphatase inhibitor of 17 kD (CPI-17), a key regulator in smooth muscle contraction, was selectively downregulated by endotoxin lipopolysaccharide (LPS) in mesenteric arteries from C57BL/6 mice and by tumor necrosis factor alpha (TNF) in cultured smooth muscle tissue and cells. Downregulation of CPI-17 by LPS was associated with LPS-induced vasodilatory shock and hypotension and was largely attributed to TNF-induced CPI-17 transcriptional suppression. By various molecular approaches, including cloning, deletion, mutation, siRNA, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP), we identified two GC-boxes in the proximal CPI-17 promoter as a novel TNF-response element that is critical for TNF-induced CPI-17 downregulation, and demonstrated that in the absence of TNF, SP1 bound to the CPI-17 promoter GC-boxes and positively regulated CPI-17 transcription, whereas in the presence of TNF, Krüppel-like factor 4 (KLF4) was markedly upregulated, competed with SP1 for binding to the CPI-17 promoter, and negatively regulated CPI-17 transcription through histone deacetylases (HDACs). Moreover, specific blockage of the TNF/KLF4/SP1/CPI-17 signaling by genetic deletion of TNF prevented mice from LPS-induced hypotension and mortality. Conclusions: These data reveal a previously unrecognized but potentially important mechanism for vasodilatory shock and hypotension in sepsis, and suggest a new therapeutic strategy for treatment of patients with sepsis.