CD19⁺CD24^hiCD38^hi B regulatory cell levels correlate with disease remission in patients with non-infectious uveitis

Abstract

Purpose : Recent studies have reported B regulatory cells (Bregs) are involved in the resolution of autoimmune diseases. In this study, we determined whether the peripheral blood immunophenotype and function of Bregs correlates with disease activity of non-infectious uveitis patients.

Methods : Clinically active (N=13; 7M: 6F) and quiescent (N=37; 18M:19F) non-infectious uveitic patients, and 10 healthy controls were recruited to the study. Isolated peripheral blood mononuclear cells (PBMC) from peripheral blood samples from patients and controls were stained with directly conjugated CD19, CD24, CD38 mAbs and then acquired and analysed by flow cytometry (BD Fortessa) for CD19⁺CD24⁺CD38⁺ and CD19⁺CD24^hiCD38^hi. For Breg functional assays, flow cytometry-sorted CD4⁺CD25^- T effector cells (N=10⁵) isolated from patients and controls peripheral blood were labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE), and co-cultured with CD19⁺CD24^hiCD38^hi cells for 72 hours and analyzed for proliferation. Statistical analyses were performed using SPSS with Kruskal-Wallis test and post-hoc Bonferroni test. A p value of <0.05 was considered significant.

Results : In comparison to both quiescent patients and controls, the frequencies of CD19⁺CD24^hiCD38^hi in CD19⁺ B cells from active patients were significantly lower (p=0.024 and 0.037, respectively). The population of CD19⁺CD24⁺CD38⁺ in active patients was also lower than quiescent patients and controls, though no statistical significance was reached (p=0.085 and 0.097, respectively). Quiescent patients displayed similar levels of CD19⁺CD24^hiCD38^hi and CD19⁺CD24⁺CD38⁺ compared with controls. In healthy controls, the proliferation of T effector cells was inhibited by Bregs in the T effector and Breg co-culture system. However, from the peripheral blood of an active patient, Breg did not demonstrate the ability to inhibit CD4⁺CD25^- T cell proliferation.

Conclusions : There were fewer Bregs in active uveitic patients than in quiescent patients and controls. Bregs in active patients showed an impaired anti-inflammatory function. The frequency of CD19⁺CD24^hiCD38^hi population in peripheral blood may be used to monitor disease progression and remission of non-infectious uveitic patients.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.