ADAM17 and obesity due to melanocortin 4 receptor deficiency: Maximal ADAM17 expression in PBCs of COVID-19 patients with obesity (BMI > 30) is explicable, considering that obesity often associates with metabolic inflammation, with which ADAM17 activity has recognized links, through proteolytic processing of pro-TNFalfa, ACE2, IL-6R and other membrane-anchored proteins in adipose tissue and other tissues [45,46].