Thromb Haemost 2021; 121(11): 1448-1463
DOI: 10.1055/s-0041-1726093
Cellular Signalling and Proteolysis

Protective Role of Activated Protein C against Viral Mimetic Poly(I:C)-Induced Inflammation

Xiaofeng Cai
1  Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States
,
1  Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States
,
Indranil Biswas
1  Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States
,
Hemant Giri
1  Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States
,
Alireza R. Rezaie
1  Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States
2  Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
› Author Affiliations
Funding This work was supported by grants awarded by the National Heart, Lung, and Blood Institute of the National Institute of Health (HL 101917 and HL 62565 to A.R.R.).

Abstract

Activated protein C (APC) is an anticoagulant plasma serine protease which exhibits potent cytoprotective and anti-inflammatory activities. Here, we studied protective effects of APC on the proinflammatory function of polyinosinic:polycytidylic acid [poly(I:C)], a synthetic analog of viral double-stranded RNA, in cellular and animal models. Poly(I:C) induced histone H3 extranuclear translocation via interaction with toll-like receptor 3 in two established endothelial cell lines. Furthermore, poly(I:C) induced histone H3 extranuclear translocation in J774A.1 macrophages and human neutrophils and formation of macrophage and neutrophil extracellular traps (ETs). Mechanistically, poly(I:C) was found to upregulate expression of peptidylarginine deiminase 4 and enhance its interaction with histone H3, thereby leading to increased histone citrullination and neutrophil ET formation. Poly(I:C) elicited proinflammatory signaling responses by inducing nuclear factor kappa B activation and disrupting endothelial cell permeability. In vivo, poly(I:C) enhanced cell surface expression of Mac-1 on neutrophils in mice and facilitated their infiltration to lung tissues. Poly(I:C) also downregulated thrombomodulin expression in mouse tissues and reduced its circulating soluble level in plasma. We demonstrate in this study that APC and a signaling-selective mutant of APC effectively inhibit proinflammatory signaling effects of poly(I:C) in both cellular and animal models. We further demonstrate that unlike the requirement for endothelial protein C receptor on endothelial cells, the integrin Mac-1 is involved in the protease-activated receptor 1-dependent APC inhibition of macrophage ET formation in J774A.1 cells. Taken together, these results support a key role for APC signaling in inhibiting the viral mimetic-induced proinflammatory signaling responses and histone translocation-associated formation of ETs by innate immune cells.

Author Contributions

X.C. designed the experiments, performed the research, and analyzed the data; S.R.P designed and performed the mouse and flow cytometry experiments and analyzed the data; I.B. designed the experiments and performed the cell permeability assay research; H.G. performed the soluble thrombomodulin ELISA experiments; A.R.R. designed the experiments, analyzed the data, and wrote the manuscript.


Supplementary Material



Publication History

Received: 08 October 2020

Accepted: 29 January 2021

Publication Date:
11 March 2021 (online)

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