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

Abstract

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-γ + (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.

Figure 1.

Representative flow cytometry data to illustrate the gating strategy for FACS analysis of T-cell subsets. Dot plot with a gate (R1) encompassing the lymphocyte population (A), CD4⁺ lymphocytes was further gated (R2) (B), dot plots represent the expression of CD200/CD200R1 on CD3 ⁺CD4⁺ cells of healthy controls (C) and of IBD patients (D), respectively. HC - healthy controls, UC - ulcerative colitis patients, CD - Crohn’s Disease patients, FS - forward scatter, SS - side scatter.

Figure 2.

Percentage of CD4 T-helper lymphocytes expressing CD200 and CD200R1. HC - healthy controls, UC - ulcerative colitis patients, CD - Crohn’s Disease patients, NS - not significant, asterisks denote statistical significance, * p < 0.05, ^** p < 0.01.

Figure 3.

Quantification of Treg, TH1, TH2, and Th17 cells in the peripheral blood from patients with IBD. Th17 and lymphocytes analyzed by flow cytometry. Boxplots show the percentage of (A) Treg (CD4⁺CD25⁺Foxp3⁺), (B) Th17 (CD4⁺ IL-17A⁺), (C) Th17/Treg ratio, (D) Th1 (CD4⁺ IFN-γ⁺), and (E) Th2 (CD4⁺ IL-4⁺) cells in the studied groups. HC - healthy controls, UC - ulcerative colitis patients, CD - Crohn’s Disease patients, NS - not significant, asterisks denote statistical significance, * p < 0.05, ^** p < 0.01.