SARS-CoV2 infection impairs the metabolism and redox function of cellular glutathione

Desirée Bartolini,Anna Maria Stabile,Sabrina Bastianelli,Daniela Giustarini,Sara Pierucci,Chiara Busti,Carmine Vacca,Anna Gidari,Daniela Francisci,Roberto Castronari,Antonella Mencacci,Manlio Di Cristina,Riccardo Focaia,Samuele Sabbatini,Mario Rende,Antimo Gioiello,Gabriele Cruciani,Ranieri Rossi,Francesco Galli

doi:10.1016/j.redox.2021.102041

Desirée Bartolini, Anna Maria Stabile + Show 17 more

Open Access

https://doi.org/10.1016/j.redox.2021.102041

Copy DOI

Journal: Redox Biology	Publication Date: Jun 10, 2021
Citations: 61	License type: cc-by

Affiliation: University of Perugia, University of Siena

Abstract

Viral infections sustain their replication cycle promoting a pro-oxidant environment in the host cell. In this context, specific alterations of the levels and homeostatic function of the tripeptide glutathione have been reported to play a causal role in the pro-oxidant and cytopathic effects (CPE) of the virus. In this study, these aspects were investigated for the first time in SARS-CoV2-infected Vero E6 cells, a reliable and well-characterized in vitro model of this infection. SARS-CoV2 markedly decreased the levels of cellular thiols, essentially lowering the reduced form of glutathione (GSH). Such an important defect occurred early in the CPE process (in the first 24 hpi). Thiol analysis in N-acetyl-Cys (NAC)-treated cells and membrane transporter expression data demonstrated that both a lowered uptake of the GSH biosynthesis precursor Cys and an increased efflux of cellular thiols, could play a role in this context. Increased levels of oxidized glutathione (GSSG) and protein glutathionylation were also observed along with upregulation of the ER stress marker PERK. The antiviral drugs Remdesivir (Rem) and Nelfinavir (Nel) influenced these changes at different levels, essentially confirming the importance or blocking viral replication to prevent GSH depletion in the host cell. Accordingly, Nel, the most potent antiviral in our in vitro study, produced a timely activation of Nrf2 transcription factor and a GSH enhancing response that synergized with NAC to restore GSH levels in the infected cells. Despite poor in vitro antiviral potency and GSH enhancing function, Rem treatment was found to prevent the SARS-CoV2-induced glutathionylation of cellular proteins. In conclusion, SARS-CoV2 infection impairs the metabolism of cellular glutathione. NAC and the antiviral Nel can prevent such defect in vitro.

Highlights

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is responsible for the Coronavirus disease 2019 (COVID-19) [1], which can present in a significant number of cases, and especially in the elderly and comorbid patients, as a severe respiratory distress syndrome with high risk of disabilities and even death [2,3]
The infection process of the influenza virus and its pro-oxidant effects in the host cell, are both reduced by the treatment with GSH analogues in in vitro models and in vivo in old mice and in lethally-infected mice [15,19], and promising results on these agents have been reported in other experimental models of viral infection [17]; again, treatments with Cys analogues, such as N-acetyl cysteine (NAC), have successfully been adopted to replenish blood GSH and to improve immune and metabolic functions in HIV-infected patients [20], and NAC is under clinical investigation in COVID-19, holding potential to prevent severe compli cations especially in the elderly and comorbid patients
Cellular thiols were investigated in Vero E6 cells 24 hpi; according to previous findings in literature [4,5], this time point in the SARS-CoV2 infection process precedes the phase in which cytopathic effect (CPE) can be detected by morphology analysis and cell viability tests, and plaque assay (72 hpi)

Summary

Introduction

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is responsible for the Coronavirus disease 2019 (COVID-19) [1], which can present in a significant number of cases, and especially in the elderly and comorbid patients, as a severe respiratory distress syndrome with high risk of disabilities and even death [2,3]. The infection process of the influenza virus and its pro-oxidant effects in the host cell, are both reduced by the treatment with GSH analogues in in vitro models and in vivo in old mice and in lethally-infected mice [15,19], and promising results on these agents have been reported in other experimental models of viral infection [17]; again, treatments with Cys analogues, such as N-acetyl cysteine (NAC), have successfully been adopted to replenish blood GSH and to improve immune and metabolic functions in HIV-infected patients [20], and NAC is under clinical investigation in COVID-19, holding potential to prevent severe compli cations especially in the elderly and comorbid patients The infection process of the influenza virus and its pro-oxidant effects in the host cell, are both reduced by the treatment with GSH analogues in in vitro models and in vivo in old mice and in lethally-infected mice [15,19], and promising results on these agents have been reported in other experimental models of viral infection [17]; again, treatments with Cys analogues, such as N-acetyl cysteine (NAC), have successfully been adopted to replenish blood GSH and to improve immune and metabolic functions in HIV-infected patients [20], and NAC is under clinical investigation in COVID-19, holding potential to prevent severe compli cations especially in the elderly and comorbid patients (recently reviewed in Ref. [21])

Methods

Results

Conclusion