The Mechanisms Linking Relative Hypercortisolism - The Common Feature Across COVID-19 Risks - To ARDS, Septic Shock, and Cytokine Dysregulation (preprint)

ABSTRACT

Covid-19 mortality risk factors share a common feature a high ratio of cortisol to DHEA, referred to as relative hypercortisolism (RHC).Starting from a low just after age 25, adult COVID-19 mortality rates rise in tandem with this ratio as DHEA levels fall by over 80% by age 70. Conversely, juvenile COVID-19 morbidity rates _fall_ with this ratio as DHEA rises to pre-adolescent levels after age 6. Moreover, RHC predicts the severity and likelihood of death for both community acquired pneumonia and septic shock, the primary COVID-19 modes of death. Consistent with this finding, DHEA prevents cytokinedysregulation in a murine leukemia retrovirus model. DHEA, byinhibiting the PI3K/AKT pathway, also inhibits viral replication.DHEA, antagonized by cortisol, maintains intracellular calciumhomeostasis, a critical function during viral infections. The cortisol to DHEA ratio determines the exon splicing of the calcium-sensitive big potassium (BKCa) channel, which exerts predominate control over cell and inner mitochondrial membrane polarization. DHEA increases BKCa calcium sensitivity, and thereby reduces calcium influx into the cell and mitochondrial matrix. This effect–together with vitamin D3/calcitriol promoted calbindin-D9k/28k, magnesium, andubiquinone–protects against mitochondrial calcium overload. Absent these key factors, the COVID-19 virus, SARS-CoV-2, like other viruses disrupts intracellular calcium homeostasis to trigger mitochondrial calcium overload in susceptible hosts. The virus then hijacks the inflammatory ER stress and unfolded protein response (UPR) for its own replication.UPR underlies the virus’s lethality. It splices X-box protein 1(XBP-1) to its active form, which in turn activates the transcription regulator SNAI1. sXBP-1 and SNAI1 shift cellular metabolism from the pentose phosphate pathway to the hexosamine biosynthesis pathway and induce insulin resistance. SNAI1 also causes epidermal-to-mesenchymal transition (EMT). In this process, SNAI1 represses transcription of epithelial and vascular endothelial cadherins along with othercritical proteins forming the tight junction barriers in the lung and vasculature. UPR also inhibits expression of the epithelial sodium channel (ENaC), which maintains alveolar fluid balance. DHEAdose-dependently reduces XBP-1 mRNA splicing in cultured hepatocytes treated with the ER stress/UPR inducer tunicamycin.RHC and insulin resistance also produce a pathological immuneresponse. Insulin resistance via mTORC1 inhibits the cell energy sensor AMPK and, consequently, the first line of defense against the virus, autophagy. Severe mitochondrial calcium overload associated with RHC oxidizes phospholipids and predisposes the cell to necrosis.Upon cell lysis, the oxidized phospholipids trigger sterileinflammation, drawing cytokine-secreting neutrophils and macrophages to the site. Further exacerbating inflammation, insulin resistance and its inhibition of PPAR-γ skews macrophage polarization to thepro-inflammatory M1 phenotype. Meanwhile, RHC promotes glucocorticoid recycling via 11β-HSD1 in thymocytes. This recycling causesactivation-induced cell death, suppresses lymphocyte countproliferation, and leads to IL-1β hypersecretion and worsening RHC.Ultimately, this cytokine storm and severe RHC induce autoimmunity.Evidence suggests this pathological state can be avoided by restoring calcium homeostasis using a combination of DHEA, vitaminD3/calcitriol, magnesium, ubiquinone, and the AMPK/SIRT1 activators, acetyl L-carnitine and alpha lipoic acid.