Increased CD4CD45RAFoxP3 cells alter the balance between Treg and Th17 cells in colitis mice.

Aim: To investigate the role of regulatory T cell (Treg) subsets in the balance between Treg and T helper 17 (Th17) cells in various tissues from mice with dextran sulfate sodium-induced colitis.

Methods: Treg cells, Treg cell subsets, Th17 cells, and CD4CD25FoxP3IL-17 cells from the lamina propria of colon (LPC) and other ulcerative colitis (UC) mouse tissues were evaluated by flow cytometry. Forkhead box protein 3 (FoxP3), interleukin 17A (IL-17A), and RORC mRNA levels were assessed by real-time PCR, while interleukin-10 (IL-10) and IL-17A levels were detected with a Cytometric Beads Array.

Results: In peripheral blood monocytes (PBMC), mesenteric lymph node (MLN), lamina propria of jejunum (LPJ) and LPC from UC mice, Treg cell numbers were increased ( < 0.05), and FoxP3 and IL-10 mRNA levels were decreased. Th17 cell numbers were also increased in PBMC and LPC, as were IL-17A levels in PBMC, LPJ, and serum. The number of FrI subset cells (CD4CD45RAFoxP3) was increased in the spleen, MLN, LPJ, and LPC. FrII subset cells (CD4CD45RAFoxP3) were decreased among PBMC, MLN, LPJ, and LPC, but the number of FrIII cells (CD4CD45RAFoxP3) and CD4CD25FoxP3IL-17A cells was increased. FoxP3 mRNA levels in CD4CD45RAFoxP3 cells decreased in PBMC, MLN, LPJ, and LPC in UC mice, while IL-17A and RORC mRNA increased. In UC mice the distribution of Treg, Th17 cells, CD4CD45RAFoxP3, and CD4CD45RAFoxP3 cells was higher in LPC relative to other tissues.

Conclusion: Increased numbers of CD4CD45RAFoxP3 cells may cause an imbalance between Treg and Th17 cells that is mainly localized to the LPC rather than secondary lymphoid tissues.