The pathogenesis of a COVID-19 respiratory infection, in a major way, is related to what is referred to as the cytokine storm [cytokine storm syndrome (CSS, hypercytokinemia, etc.], i.e., it is a hyper-inflammatory response.
During this response, an explosive production of proinflammatory cytokines such as TNF-α IL-1β, and others occurs, greatly exaggerating the generation of molecule-damaging reactive oxygen species (free radicals) . In severe cases, the cytokine storm is responsible for the most obvious signs of a COVID-19 infection including fever, lung injury which causes cough and shortness of breath (and the long-term complication, lung fibrosis) and in death.
A causative factor related to the hyper-inflammatory state of immune cells is their ability to dramatically change their metabolism. Similar to cancer cells in many solid tumors, immune cells such as macrophages/monocytes under inflammatory conditions abandon mitochondrial oxidative phosphorylation for ATP production in favor of cytosolic aerobic glycolysis (also known as the Warburg effect) . This switch is driven by the transcription factor HIF-1α (hypoxia inducible factor-1α) and the serine/threonine kinase, mTOR (mammalian target of rapamycin) and other proteins The change to aerobic glycolysis allows immune cells to become highly phagocytic, accelerate ATP production, intensify their oxidative burst and to provide the abundant metabolic precursors required for enhanced cellular proliferation and increased synthesis and release of cytokines.