MPO and metabolic disease: He et al. demonstrated that insulin resistance is due to SARS-CoV-2 upregulation of RE1 silencing transcription factor (REST) expression to regulate the metabolic factors myeloperoxidase (MPO), apelin, and myostatin gene expression, that such metabolic disorders are not improved by the disappearance of the virus in vivo, and that this pathology develops over time (He et al., 2021).