Human Monocytes Heterogeneity And Its Implication In Uveitis Therapy

Abstract

Purpose: : The expression of CD14 and CD16 defines three monocyte subsets:CD14 ^highCD16^-, CD14^highCD16⁺, and CD14^lowCD16⁺ cells. The goals of this study are to characterize these 3 populations and evaluate the association between monocyte subsets and uveitis therapy.

Methods: : Human peripheral blood mononuclear cells (PBMCs) were isolated from the blood of healthy donors using a Ficoll gradient centrifugation protocol. Monocyte phenotying was performed using 4 color flow cytometry staining protocol. LPS and IFNγ were used in vitro to polarize classically-activated monocytes and IL-4 was used to polarize alternatively-activated monocytes. Real-time polymerase chain reactions (RT-PCR) were used to detect mRNA expression of cytokines and chemokines.

Results: : Classically-activated monocytes present higher percentage expression of CD14^highCD16^- than do alternative and unpolarized monocytes. RT-PCR showed that CD14^highCD16^- monocytes expressed higher IL-6, IL-8, IL-10, IL-1β, CXCL1, CXCL3, CXCL5 and CXCL6 levels than did CD14^highCD16⁺ monocytes. The expression of CD163, a scavenger receptor on monocytes which is believed to be a regulatory monocyte marker, is lower in CD14^lowCD16⁺ and CD14^highCD16^- cells than in CD14^highCD16⁺ monocytes. Importantly, we observed a higher percentage of CD14^highCD16⁺, a lower percentage of CD14^lowCD16⁺ and CD14^highCD16^- populations in quite uveitis patients on immuno-suppressive therapy than inactive patients not on immunosuppressives and normal donors [p<0.05].

Conclusions: : CD14^lowCD16⁺ and CD14^highCD16^- monocyte populations may represent subsets of proinflammatory monocytes. Our data suggest a potential role for monocyte phenotyping in understanding the effects of immuno-therapy in uveitis patients.

Keywords: autoimmune disease • uveitis-clinical/animal model