Deubiquitinase function of A20 maintains and repairs endothelial barrier after lung vascular injury

Dheeraj Soni,Dirk Schlüter,Dong-Mei Wang,Stephen M Vogel,Manish Mittal,Sushil C Regmi,Chinnaswamy Tiruppathi

doi:10.1038/s41420-018-0056-3

Abstract

Vascular endothelial cadherin (VE-cad) expression at endothelial adherens junctions (AJs) regulates vascular homeostasis. Here we show that endothelial A20 is required for VE-cad expression at AJs to maintain and repair the injured endothelial barrier. In endothelial cell (EC)-restricted Tnfaip3 (A20) knockout (A20∆EC) mice, LPS challenge caused uncontrolled lung vascular leak and persistent sequestration of polymorphonuclear neutrophil (PMNs). Importantly, A20∆EC mice exhibited drastically reduced VE-cad expression in lungs compared with wild-type counterparts. Endothelial expression of wild-type A20 but not the deubiquitinase-inactive A20 mutant (A20C103A) prevented VE-cad ubiquitination, restored VE-cad expression, and suppressed lung vascular leak in A20∆EC mice. Interestingly, IRAK-M-mediated nuclear factor-κB (NF-κB) signaling downstream of TLR4 was required for A20 expression in ECs. interleukin-1 receptor-associated kinase M (IRAK-M) knockdown suppressed basal and LPS-induced A20 expression in ECs. Further, in vivo silencing of IRAK-M in mouse lung vascular ECs through the CRISPR-Cas9 system prevented expression of A20 and VE-cad while augmenting lung vascular leak. These results suggest that targeting of endothelial A20 is a potential therapeutic strategy to restore endothelial barrier integrity in the setting of acute lung injury.

Highlights

Expression of vascular endothelial cadherin (VE-cad) at endothelial adherens junctions (AJs) is vital for endothelial barrier integrity[1,2]
These findings demonstrate that A20 deficiency augments LPS-induced inflammatory signaling in lung ECs (LECs)
We observed significantly increased concentrations of tumor necrosis factor (TNF)-α and monocyte chemoattractant protein-1 (MCP-1) in the lungs of A20ΔEC mice compared with WT (Fig. 2d)

Summary

Introduction

Expression of vascular endothelial cadherin (VE-cad) at endothelial adherens junctions (AJs) is vital for endothelial barrier integrity[1,2]. Loss of VE-cad expression at endothelial AJs induces persistently increased vascular permeability and uncontrolled extravasation of leukocytes into lungs leading to inflammatory lung injury[3,4,5]. VE-cad phosphorylation at Y-658, Y-685, and Y-731 induces disassembly of endothelial AJs that results in increased vascular permeability and PMN extravasation into lungs[7,8,9,10,11]. The transmembrane protein, VE protein tyrosine phosphatase (VE-PTP), exclusively expressed in endothelial cells (ECs), interacts with and constitutively dephosphorylates VE-cad to maintain endothelial barrier integrity[10,12,13]. Challenge with infectious Gram-negative bacterial cell wall component lipopolysaccharide (LPS)

Methods

Results

Conclusion