FoxP3+CD4+CD25+ T cells with regulatory properties can be cultured from colonic mucosa of patients with Crohn's disease

Abstract

CD4⁺CD25⁺ regulatory T cells (T_regs) are involved in the maintenance of peripheral tolerance and ensure a balanced immune response competent of fighting pathogens and at the same time recognizing commensals as harmless. This feature is lost in Crohn's disease (CD). The forkhead/winged helix transcription factor FoxP3 is a master gene for T_reg function and defects in the FoxP3 gene lead to a clinical picture similar to inflammatory bowel disease (IBD). Murine colitis can be cured by adoptive transfer of T_regs and ex vivo-generated gut-specific T_regs represent an attractive option for therapy in CD. Thus, defective T_regs could contribute to the development of CD. We cultured biopsies of colonic mucosa in the presence of high concentrations of interleukin (IL)-2 and IL-4 to overcome the anergic nature of naturally occurring CD4⁺CD25⁺ T_regs in the mucosa. We investigated the expression of FoxP3 and regulatory potential of gut-derived CD4⁺CD25⁺ T cells cultured from patients with CD and healthy individuals. The FoxP3 expression was analysed by reverse transcriptase polymerase chain reaction (RT-PCR), and the suppressive effect of FoxP3⁺CD4⁺CD25⁺ T cells on proliferation and cytokine production of autologous CD4⁺ T cells was assessed by flow cytometry. Cultured gut-derived T cells with CD4⁺CD25⁺ phenotype expressed FoxP3 and were able as the freshly isolated T_regs from peripheral blood to suppress proliferation and cytokine production of autologous CD4⁺ T cells. Thus, we demonstrate that FoxP3⁺CD4⁺CD25⁺ T cells with regulatory properties can be propagated in vitro from inflamed mucosa of CD patients, which may be of interest in adoptive immunotherapy.