Increased Expression of Chondroitin Sulfotransferases following AngII may Contribute to Pathophysiology Underlying Covid-19 Respiratory Failure: Impact may be Exacerbated by Decline in Arylsulfatase B Activity

The spike protein of SARS-CoV-2 binds to respiratory epithelium through the ACE2 receptor, an endogenous receptor for Angiotensin II (AngII). The mechanisms by which this viral infection leads to hypoxia and respiratory failure have not yet been elucidated. Interactions between the sulfated glycosaminoglycans heparin and heparan sulfate and the SARS-CoV-2 spike glycoprotein have been identified as participating in viral adherence and infectivity. In this brief report, we present data indicating that stimulation of vascular smooth muscle cells by AngII leads to increased expression of two chondroitin sulfotransferases (CHST11 and CHST15), which are required for the synthesis of the sulfated glycosaminoglycans chondroitin 4-sulfate (C4S) and chondroitin 4,6-disulfate (CSE). We suggest that increased expression of these chondroitin sulfotransferases and the ensuing production of chondroitin sulfates may contribute to viral adherence to bronchioalveolar cells and to the progression of respiratory disease in Covid-19. The enzyme Arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase), which removes 4-sulfate groups from the non-reducing end of chondroitin 4-sulfate residues, is required for degradation of C4S and CSE. In hypoxic conditions or following treatment with chloroquine, ARSB activity is reduced. Decline in ARSB can contribute to ongoing accumulation and airway obstruction by C4S and CSE. Decline in ARSB leads to increased expression of Interleukin(IL)-6 in human bronchial epithelial cells, and IL-6 is associated with cytokine storm in Covid-19. These findings indicate how chondroitin sulfates, chondroitin sulfotransferases, and chondroitin sulfatases may participate in the progression of hypoxic respiratory insufficiency in Covid-19 disease and suggest new therapeutic targets.