Ivermectin Affects Neutrophil-Induced Inflammation Through Inhibition of Hydroxylysine but Stimulation of Cathepsin G and Phenylalanine Secretion

The invasion and integrin-dependent adhesion of neutrophils to lung tissues and their secretion lead to the development of pneumonia in various pulmonary pathologies, including acute respiratory distress syndrome in coronavirus disease. We studied the effect of ivermectin, a possible therapeutic agent for inflammation and cancer, on integrin-dependent neutrophil adhesion to fibronectin and the concomitant secretion. Ivermectin did not affect the attachment of neutrophils to the substrate and the reactive oxygen species production but sharply inhibited the adhesion-induced release of hydroxylysine and stimulated the release of phenylalanine and cathepsin G. Hydroxylysine is a product of lysyl hydroxylase, which is overexpressed in tumor cells with an increased ability to invade and metastasize. The inhibition of hydroxylysine release by ivermectin, by analogy, may indicate the suppression of neutrophil invasion into tissue. The increase in the release of phenylalanine in our experiments coincided with the secretion of cathepsin G, which indicates the possible role of this enzyme in the cleavage of phenylalanine. What is the substrate in such a reaction is unknown. We demonstrated that exogenously added angiotensin II (1-8) can serve as a substrate for phenylalanine cleavage. Mass spectrometry revealed the formation of angiotensin II (1-7) in the secretion of neutrophils, which attached to fibronectin in the presence of ivermectin and exogenous angiotensin II (1-8), indicating a possible involvement of ivermectin in the inactivation of angiotensin II.