Expression of CD200R1 and its Ligand CD200 on T-helper Lymphocytes of Pediatric Patients with Ulcerative Colitis and Crohn's Disease

Background: CD200 and its receptor CD200R are both type I membrane glycoproteins that modulate the activity of myeloid and lymphoid cells, and their interaction is functionally important in the suppression of effector T-cell responses by regulatory T-cells. We aimed to investigate the extent of expression of CD200 and CD200R1 on CD4(+) T-cells in blood of children with ulcerative colitis (UC) and Crohn's disease (CD) and to explore their correlations with effector T cell subsets, regulatory T cells (Treg), and routine clinical and serological markers. Methods: The frequencies of blood CD4(+) expressing CD200 and CD200R1 as well as T-helper CD4(+)CD25(+)Foxp3(+) Treg, CD4(+) IL-17(+) (Th17), CD4(+) IFN-gamma (+) (Th1), and CD4(+)IL-4(+) (Th2) were estimated by flow cytometry in 23 patients with CD, 14 with UC, and 14 healthy volunteers (HCs). The clinical and inflammatory markers were also investigated. Results: IBD patients showed decreased CD4(+)CD200R1(+) T-cells, whereas, CD4(+)CD200(+) T-cells were significantly higher in patient groups compared with healthy controls. Treg cells were found significantly decreased in the patients with UC and CD compared with healthy controls (both at p < 0.01). The percentage of Th17 was found significantly increased in CD (p < 0.05) compared with UC patients and healthy subjects (p = 0.014). CD200(+)CD4(+) T-cells showed significant positive correlations with ESR, Th1, and Th17 (r = 0.438, p < 0.05; r = 0.411, p < 0.05; r = 0.492, p < 0.01, respectively). CD200R1(+)CD4(+) T-cells correlated positively with Th2 and Treg (r = 0.482, p < 0.01, and r = 0.457, p < 0.01, respectively) and negatively with ESR (r =-0.387, p < 0.01). Conclusions: Our study demonstrates an aberrant expression of CD200/CD200R1 on CD4(+) T-cells in IBD patients and these data may have potent pathological significance in IBD pathophysiology.