CRP and COVID-19: In patients hospitalized with COVID-19 (n = 172), serum levels of tryptophan and indole-3-propionate (IPA) negatively correlated with serum levels of many proinflammatory mediators (including C-reactive protein and Serum amyloid A), while C-glycosyltryptophan (C-Trp), indole-3-lactic acid (ILA) and indole-3-acetic acid (IAA) levels were positively correlated with levels of acute phase proteins, proinflammatory cytokines, alarmins and chemokines.