N-Acetylcysteine Reverses Antiretroviral-Mediated Microglial Activation by Attenuating Autophagy-Lysosomal Dysfunction.

Ashutosh Tripathi,Maria E Burkovetskaya,Palsamy Periyasamy,Fang Niu,Ming-Lei Guo,Ernest T Chivero,Shilpa Buch,Annadurai Thangaraj

doi:10.3389/fneur.2020.00840

Abstract

Successful suppression of viral replication by combined antiretroviral therapy (cART) in HIV-1 infected individuals is paradoxically also accompanied by an increased prevalence of HIV-associated neurocognitive disorders (HAND) in these individuals. HAND is characterized by a state of chronic oxidative stress and inflammation. Microglia are extremely sensitive to a plethora of stimuli, including viral proteins and cART. The current study aimed to assess the effects of cART-mediated oxidative stress on the induction of inflammatory responses in microglia. In the present study, we chose a combination of three commonly used antiretroviral drugs—tenofovir disoproxil fumarate, emtricitabine, and dolutegravir. We demonstrated that exposure of microglia to the chosen cART cocktail induced generation of reactive oxygen species, subsequently leading to lysosomal dysfunction and dysregulated autophagy, ultimately resulting in the activation of microglia. Intriguingly, the potent antioxidant, N-acetylcysteine, reversed the damaging effects of cART. These in vitro findings were further corroborated in vivo wherein cART-treated HIV transgenic (Tg) rats demonstrated increased microglial activation, exaggerated lysosome impairment, and dysregulated autophagy in the prefrontal cortices compared with HIV Tg rats not exposed to cART. Similar to in vitro findings, the treatment of HIV Tg rats with N-acetylcysteine also mitigated the deleterious effects of cART. Taken together, our findings suggest that oxidative stress-mediated lysosomal dysfunction plays a critical role in the pathogenesis of HAND in drug-treated HIV-infected individuals and that antioxidant-mediated mitigation of oxidative stress could thus be considered as an adjunctive therapeutic strategy for ameliorating/dampening some of the neurological complications of HAND.

Highlights

With the advent of combined antiretroviral therapy, HIV infection has transformed from a death sentence to a more chronic and manageable disease [1,2,3]
Our recent findings have shown that combined antiretroviral therapy (cART)-mediated lysosomal dysfunction causes dysregulated autophagy leading, in turn, to microglial activation [13]
We sought to determine the possible involvement of reactive oxygen species (ROS) in cART-mediated lysosomal dysfunction and autophagy dysregulation. rat primary microglial cells (rPMs) were exposed to cART (TDF, fumarate (TDF) and emtricitabine (FTC), and DTG), each at 5 μM for various time points (0–24 h), and assessed for a generation of ROS using the DCFH-DA assay

Summary

Introduction

With the advent of combined antiretroviral therapy (cART), HIV infection has transformed from a death sentence to a more chronic and manageable disease [1,2,3]. The mechanism(s) underlying pathogenesis of HAND is not clearly understood, associated oxidative stress, immune activation, and inflammation have been implicated in the process [4, 5]. Microglia are the predominant brain-resident macrophages that maintain central nervous system (CNS) homeostasis under basal conditions and during moderate activation. On the other hand, impairs the ability of microglia to maintain cellular homeostasis and leads to significant neuronal dysfunction and cognitive impairment, with exacerbated neuroinflammation in the CNS [6, 7]. Exacerbated microglial activation and neuroinflammation are hallmark features of HAND pathogenesis in HIV-infected individuals on cART [8,9,10]. Impaired lysosomal functioning has been shown to underlie microglial activation and increased neuroinflammation [14, 15]. Findings from our group have identified the role of lysosomal dysfunction in cARTmediated dysregulation of autophagy [13]

Methods

Results

Conclusion