Phenotype and pathological significance of MCAM+ (CD146+) T cell subset in psoriatic arthritis

Abstract

Background: CD146 (MCAM-melanoma cell adhesion molecule) is a cell surface adhesion molecule for Laminin 411. T cells expressing MCAM are mainly responsible for IL-17 production. IL-17 secreting T helper cells (Th17 cells) are critical for the pathogenesis of psoriatic arthritis (PsA). Here we hypothesized enrichment of CD146+IL-17+ memory T cells in PsA synovium and studied the association of CD146 expression and CD4+IL-17+ activated memory (CD11a+CD45RO+) T cells in synovial fluid and blood of PSA, rheumatoid arthritis (RA, a positive control) and osteoarthritis (OA) patients. Methods: Hi-D FACS studies were done to identify IL-17 in CD4+CD146+CD45RO+ and CD8+CD146+CD45RO+ T cells. Results: We observed that effector CD146+(MCAM+) T cells are enriched at the synovial inflammation site in PsA. Conclusion: As CD146+ T cells are a key resource for IL-17 it is likely that the enrichment of these MCAM+ pathologic cells are critical for the disease process of PsA.