Modified Proline Metabolism and Prolidase Enzyme in COVID-19

Objective The aim of the study was to evaluate proline metabolism in patients affected by COVID-19. Materials and Methods This case-control study consisted of 116 patients with COVID-19 and 46 healthy individuals. Tests related to proline metabolism (prolidase, proline, hydroxyproline, glutamic acid, manganese) and copper and zinc tests were analyzed. Results The levels of proline and hydroxyproline amino acids and the prolidase enzyme were found to be lower and glutamic acid was found to be higher in the COVID-19 group compared to the healthy group (P = .012, P < .001, P < .001, and P < .001, respectively). The copper/zinc ratio was higher in patients with COVID-19 than in healthy individuals (P < .001). Significant correlations were found between proline metabolism tests and inflammatory and hemostatic markers commonly used in COVID-19. Conclusion The proline metabolic pathway was affected in COVID-19. Relationships between proline pathway–related tests and inflammatory/hemostatic markers supported the roles of proline metabolism in proinflammatory and immune response processes.