Abstract
Purpose:
Regulatory B cells (Bregs), characterized by expression of the immunoregulatory cytokine IL-10, have been implicated in the suppression of excessive inflammatory responses that lead to inflammatory and autoimmune mediated diseases (Ann Rev Imm 30:221, 2012). However, it is not clear whether it has a role in suppressing intraocular inflammation and/or the maintenance of ocular immune privilege. In this study, we have therefore examined whether the suppression of experimental autoimmune uveitis (EAU) or recovery from EAU correlates with expansion of Bregs.
Methods:
Autoimmune uveitis was induced by active immunization with IRBP (interphotoreceptor retinoid-binding protein in CFA (Complete Freund’s adjuvant) in C57BL/6J mice. Disease progression was monitored by clinical grading of EAU by fundoscopy and histology. To characterize B cell populations recruited into the spleen and draining lymph-nodes at the peak of the disease (day 21 post-immunization) or during the recovery phase of EAU (day 28 post-immunization) single cell suspensions from these tissues were stained with anti-CD3, CB4, CD19, CD1d, CD5, CD21, CD23, IgM, and IgD and analyzed by multicolor flow cytometry. Cells were also stimulated with LPS/PMA/Ionomycin for 5 hour and intracellular IL-10 was measured FACS. Naïve CD19+ B cells were sorted and then activated by anti-CD40 antibody or LPS for IL-10 detection by RT-PCR and intracellular cytokine staining.
Results:
We show that total number of B cells were significantly increased in spleen and draining lymph nodes during EAU. We further show that the major regulatory B cell population at day 21 post immunization were CD1dhi CD5hi IL-10-producing B cells. Interestingly, we found that there were twice as many IL-10-producing B cells (5.4%) than IL-10-producing T cells (2.4%), suggesting that Breg may play a role during the recovery phase of the disease.
Conclusions:
We show here for the first time that Breg are expanded during autoimmune uveitis and may play important role in suppressing intraocular inflammation and in the maintenance of ocular immune privilege.
Keywords: 746 uveitis-clinical/animal model •
555 immunomodulation/immunoregulation •
688 retina