Özkan Y.Kandemir H.Sapmaz Ş.Y.Taneli F.2024-07-222024-07-22202122113649http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/13415The biological mechanisms underlying obsessive–compulsive disorder (OCD) are not sufficiently elucidated. Chronic inflammation and oxidative stress were shown to increase neopterin and decrease tetrahydrobiopterin (BH4) levels by activating the neopterin–BH4 pathway. This study compared serum TGF-β1, TNF-α, IL-1β, IL-2, IL-6, IL-10, IL-17, neopterin, BH4, and nitric oxide (NO) levels between child and adolescent patients diagnosed with OCD and a healthy control group. The study included 29 patients diagnosed with OCD (comorbidity free, drug free) and 28 healthy children as an aged and sex matched control group. Serum samples were analyzed for TGF-β1, TNF-α, IL-1β, IL-2, IL-6, IL-10, IL-17, neopterin, and BH4 by using enzyme-linked immunosorbent assay method, and NO concentrations were assessed by colorimetric method based on Griess reaction. All cytokine levels were found to be low, but this decrease was statistically significant only for TGF-β1. The neopterin and NO levels were significantly higher and BH4 significantly lower in children with OCD compared to the healthy control group. Also, a statistically significant correlation was found between NO, neopterin, and BH4 levels. The results of our study show that the levels of TGF-β1 and NO and the activation of the neopterin–BH4 pathway may be implicated in the pathophysiology of OCD. © 2021 Elsevier Inc.Englishinterleukin 10interleukin 17interleukin 1betainterleukin 2interleukin 6neopterinnitric oxidesapropterintransforming growth factor beta1tumor necrosis factoradolescentArticlechildclinical articlecolorimetrycontrolled studycross-sectional studydisease durationdisease severityenzyme linked immunosorbent assayfemalehumaninflammationmaleobsessive compulsive disorderoxidative stresspathophysiologyprotein blood levelsignal transductionArticle10.1016/j.jocrd.2021.100649