1. Introduction
The global outbreak of the novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) has rapidly evolved into a global pandemic with enormous consequences. It has caused significant mortality and loss of capital, with a struggling global economy to contain the pandemic (Douglas et al., 2020). This virus, which is the third zoonotic virus next to SARS-CoV and Middle East Respiratory Syndrome (MERS-CoV), was first identified in Wuhan, Hubei Province in China in December 2019, from where it has spread to all countries and territories of the globe (Velavan and Meyer, 2020). The initial signs of SARS-CoV-2 infection such as pneumonia, multiple organ failure and acute respiratory distress syndrome are elicited through the actions of the immune system (Douglas et al., 2020; Velavan and Meyer, 2020). Various immunopathological changes in patients with SARS-CoV-2 infection have been documented in which lymphopenia, abnormalities in granulocytes and monocytes in serum as well as increase in cytokine production have been reported. These pathological changes seen in the upper respiratory tract is due to uncontrollable viral replication, leading to influx of neutrophils, macrophages and monocytes and elevated production of pro-inflammatory cytokines, the so-called cytokine storm syndrome (Douglas et al., 2020; Velavan and Meyer, 2020).
Current studies have shown that the kidneys are badly affected during SARS-CoV-2 infection, leading to kidney injury especially in patients with comorbidities, and worsening kidney conditions with increased mortality of COVID-19 patients with pre-existing chronic kidney disease, renal cancer, diabetic nephropathy, end-stage kidney disease as well as dialysis and kidney transplant patients (Carriazo et al., 2020; Kudose et al., 2020; Pei et al., 2020; Wald and Bagshaw, 2020). In the search for antiviral agents for the treatment of COVID-19, hydrogen sulfide (H2S), a gas known for its distinct “rotten-egg” smell and established as the third member of a family of gaseous signaling molecules, is emerging as a potential candidate. In this review, we summarize the global impact of COVID-19 on pathological conditions involving the kidney and discuss the emerging role of H2S as a potential COVID-19 therapy.