Differentiated all-trans retinoic acid response of naive CD4+CD25- cells isolated from rats with collagen-induced arthritis and healthy ones under in vitro conditions.

AIM O THE STUDY: To compare the potential of CD4+CD25- cells, isolated from both healthy rats and rats with CIA (Collagen-Induced Arthritis), for differentiation into regulatory T cells in the presence of all-trans retinoic acid in order to learn more about the activation mechanisms and therapeutic potential of regulatory T cells. MATERIAL AND METHODS: Sorted CD4+CD25- cells were cultured in vitro with/without ATRA, and then the frequency of regulatory T cells and their ability to secrete IL-10 by CD4+ FOXP3+ cells was examined. Gene expression of the foxp3, rarα, rarß, rxrß, and ppar ß/δ and protein expression of the Rarα, Rarß, and Rxrß in cells after stimulation with ATRA were also investigated. RESULTS: CD4+CD25- cells isolated from healthy animals or from animals with CIA are characterised by different potential of the differentiation into CD4+CD25+ FOXP3+ cells. Retinoic acid receptor Rxrß is present in the CD4+CD25- cells isolated from rats with CIA. CONCLUSIONS: We showed that although ATRA did not increase the frequency of Treg in culture, it significantly increased expression of rarß and rxrß only in lymphocytes taken from diseased animals and foxp3 expression only in healthy animals. Moreover, after ATRA stimulation, the frequency of Treg-produced IL-10 tended to be lower in diseased animals than in the healthy group. The results imply that the potential of naïve cell CD4 lymphocytes to differentiate into Tregs and their putative suppressive function is dependent on the donor's health status.

Adoptively transferred Tregs accumulate in a site-specific manner and ameliorate signs of less advanced collagen-induced arthritis progress in rats.

AIM: The aim of the study was to assess the therapeutic effect and migration of adoptively transferred Tregs in the course of collagen-induced arthritis (CIA) in rats. METHODS: Sorted CD4(+)CD25(+) cells were cultured in the presence of 17-ß-estradiol, stained with CellTracker and then administered into the articular capsule of ankle joint of animals in different stages of CIA progression. RESULTS: Tregs diminished CIA signs only in animals with less advanced disease progress. Moreover, migration of transferred cells into the LN in the near proximity of the injection site and with distal location was almost completely stopped in animals with fully developed CIA. CONCLUSION: Disease progression-related differences in migratory potential of in vitro induced Tregs may be responsible for the failure of cellular therapy during the advanced stages of CIA.