Cell type-specific roles of PAR1 in Coxsackievirus B3 infection

Michael F Bode,Tomohiro Kawano,Ursula Rauch,Vanthana Bharathi,David Martinez,Yohei M Hisada,Grant J Egnatz,Nigel Mackman,Silvio Antoniak,Alice Weithauser,Clare M Schmedes,Leah Rosenfeldt,Joseph S Palumbo

doi:10.1038/s41598-021-93759-8

Abstract

Protease-activated receptor 1 (PAR1) is widely expressed in humans and mice, and is activated by a variety of proteases, including thrombin. Recently, we showed that PAR1 contributes to the innate immune response to viral infection. Mice with a global deficiency of PAR1 expressed lower levels of CXCL10 and had increased Coxsackievirus B3 (CVB3)-induced myocarditis compared with control mice. In this study, we determined the effect of cell type-specific deletion of PAR1 in cardiac myocytes (CMs) and cardiac fibroblasts (CFs) on CVB3-induced myocarditis. Mice lacking PAR1 in either CMs or CFs exhibited increased CVB3 genomes, inflammatory infiltrates, macrophages and inflammatory mediators in the heart and increased CVB3-induced myocarditis compared with wild-type controls. Interestingly, PAR1 enhanced poly I:C induction of CXCL10 in rat CFs but not in rat neonatal CMs. Importantly, activation of PAR1 reduced CVB3 replication in murine embryonic fibroblasts and murine embryonic cardiac myocytes. In addition, we showed that PAR1 reduced autophagy in murine embryonic fibroblasts and rat H9c2 cells, which may explain how PAR1 reduces CVB3 replication. These data suggest that PAR1 on CFs protects against CVB3-induced myocarditis by enhancing the anti-viral response whereas PAR1 on both CMs and fibroblasts inhibits viral replication.

Highlights

Protease-activated receptor 1 (PAR1) is widely expressed in humans and mice, and is activated by a variety of proteases, including thrombin
Expression of transcription factor 21 (TCF21)-promotor controlled Cre recombinase after tamoxifentreatment for 5 days resulted in significantly reduced expression of PAR1 in hearts of PAR1ΔCF mice compared to the tamoxifen-treated control mice (Fig. 1A)
We determined the effect of deleting PAR1 in either cardiac fibroblasts (CFs) or cardiac myocytes (CMs) on Coxsackievirus B3 (CVB3)-induced myocarditis

Summary

Introduction

Protease-activated receptor 1 (PAR1) is widely expressed in humans and mice, and is activated by a variety of proteases, including thrombin. We showed that PAR1 reduced autophagy in murine embryonic fibroblasts and rat H9c2 cells, which may explain how PAR1 reduces CVB3 replication These data suggest that PAR1 on CFs protects against CVB3-induced myocarditis by enhancing the anti-viral response whereas PAR1 on both CMs and fibroblasts inhibits viral replication. Activation of TLR3 induces the expression of interferons (IFNs) and chemokines, such as CXCL10, that coordinate the early immune response to viral infection[5,14,15,16]. Cardiotropic viruses, such as the single-stranded RNA(+) virus Coxsackievirus B3 (CVB3), cause m yocarditis[17,18,19]. CVB3-induced myocarditis in mice and humans is reduced by IFN-α and IFN-β24,27–29

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Conclusion