Oxidative Stress Induces Mitochondrial Compromise in CD4 T Cells From Chronically HCV-Infected Individuals.

Madison Schank,Sushant Khanal,Jonathan P Moorman,Yi Zhang,Lam Ngoc Thao Nguyen,Zhi Q Yao,Xindi Dang,Xiao Y Wu,Shunbin Ning,Ling Wang,Mohamed El Gazzar,Juan Zhao,Dechao Cao,Jinyu Zhang

doi:10.3389/fimmu.2021.760707

Abstract

We have previously shown that chronic Hepatitis C virus (HCV) infection can induce DNA damage and immune dysfunctions with excessive oxidative stress in T cells. Furthermore, evidence suggests that HCV contributes to increased susceptibility to metabolic disorders. However, the underlying mechanisms by which HCV infection impairs cellular metabolism in CD4 T cells remain unclear. In this study, we evaluated mitochondrial mass and intracellular and mitochondrial reactive oxygen species (ROS) production by flow cytometry, mitochondrial DNA (mtDNA) content by real-time qPCR, cellular respiration by seahorse analyzer, and dysregulated mitochondrial-localized proteins by Liquid Chromatography-Mass Spectrometry (LC-MS) in CD4 T cells from chronic HCV-infected individuals and health subjects. Mitochondrial mass was decreased while intracellular and mitochondrial ROS were increased, expressions of master mitochondrial regulators peroxisome proliferator-activated receptor 1 alpha (PGC-1α) and mitochondrial transcription factor A (mtTFA) were down-regulated, and oxidative stress was increased while mitochondrial DNA copy numbers were reduced. Importantly, CRISPR/Cas9-mediated knockdown of mtTFA impaired cellular respiration and reduced mtDNA copy number. Furthermore, proteins responsible for mediating oxidative stress, apoptosis, and mtDNA maintenance were significantly altered in HCV-CD4 T cells. These results indicate that mitochondrial functions are compromised in HCV-CD4 T cells, likely via the deregulation of several mitochondrial regulatory proteins.

Highlights

Hepatitis C virus (HCV) infection is currently an ongoing health problem worldwide
These results suggest that CD4 T cell mitochondrial function and cellular metabolism are compromised during chronic HCV infection, which contribute to aberrant T cell homeostasis and immune failure
Given the critical role of mitochondria on cellular metabolism and viability, we examined T cell homeostasis and mitochondrial functions in CD4 T cell subpopulations in Peripheral blood mononuclear cells (PBMCs) by measuring MitoTracker Orange (MO) for the level of intracellular reactive oxygen species (ROS) and MitoTracker Green (MG) for mitochondrial mass

Summary

Introduction

Hepatitis C virus (HCV) infection is currently an ongoing health problem worldwide. Despite highly effective direct-acting antiviral (DAA) therapies successfully improving the efficacy of HCV treatment, the annual rate of new HCV infection continues to increase, especially in individuals between the ages of 20-30, which increases the potential risk of HCV as a public health threat due to HCV-induced immune dysfunction [1,2,3,4,5,6]. Individuals with chronic HCV infection often demonstrate increased oxidative stress with inflammation, disruption to mitochondrial functions, metabolic disorders, and the development of severe complications including liver cirrhosis and hepatocellular carcinoma [7,8,9,10,11,12,13]. Several studies have detailed accelerated rates of cellular exhaustion and senescence following HCV infection in CD8 T cells, contributing to the potential reduction in viral clearance; little is known, about mitochondrial function following chronic HCV infection in CD4 T cells, which are essential for vaccine responses and activation of adaptive immunity [15,16,17,18]. Given the high rates of blunted vaccine responses in chronically HCV-infected patients, further investigating CD4 T cells provides critical information regarding T cell dysregulation and viral persistence [2, 4,5,6]

Methods

Results

Conclusion