YKL-40 as a novel diagnostic biomarker in Toxoplasmosis

Toxoplasmosis is one of the most globally prevalent zoonotic infection caused by an obligate, intracellular parasite called Toxoplasma gondii. Toxoplasmosis actively triggers an acute immune response and inflammatory reactions, which causes serious pathological changes in various tissues in the human body, and more evidently localizes in different nervous tissues of various body organs. The YKL-40 is a glycoprotein secreted by numerous cell types in different patterns associated with various pathological processes such as inflammatory reactions, tissue remodeling, and fibrosis, and is a disease-specific biomarker of neuroinflammation. Therefore, this study aimed to determine whether the YKL-40 is markedly increased in toxoplasmosis or not and whether its level is different between the acute and chronic phases of the infection to determine if it can be used as a clinically useful biomarker in the diagnosis, and determination of disease severity and follow-up of toxoplasmosis. Accordingly, a total of 80 serum samples were collected from previously diagnosed female patients of different ages with toxoplasmosis. In addition, serum samples of 10 healthy females were used as the control. Patients were first divided into two groups (30 patients with acute infection, and 50 patients with chronic infection) depending on the results of detection of specific anti-Toxoplasma IgM and IgG by enzyme-linked immunosorbent assay (ELISA). The level of YKL-40 was then measured in the patients' serum by ELISA. The statistical analysis of data clearly disclosed very highly significant differences (P < 0.001) between the level of YKL-40 in the acute infection group and healthy controls, chronic infection group and healthy controls, and between the groups with acute and chronic infections. These findings led to conclude that YKL-40 classify as a unique and sophisticated biomarker in the diagnosis of toxoplasmosis where it can vitally be used to detect the stage of the disease, whether acute or chronic, besides its ability to detect the infection.