Arthroplasty surgery alters the local immune composition of the knee joint by causing increases in specific lymphocyte populations.

Abstract

Abstract Objective We aimed to determine how the innate and adaptive immune cell composition and cytokine profiles of the knee joint microenvironment are altered in replaced knees compared to native knees. Methods Upon IRB approval, we obtained peripheral blood (PBMC) and synovial fluid (SF) from 14 native knees with osteoarthritis (OA) and 12 replaced knees at least 6 months after arthroplasty surgery, comprising 26 total patients. All PBMC and SF samples were analyzed by Flow Cytometry, and utilizing multidimensional reduction analysis via TriMap and clustering analysis by FlowSOM, cell clusters were phenotyped for identification of unique populations of cells. Additionally all samples were analyzed for cytokine/chemokine profiles using 65-Plex ProcartaPlex assays. Results Overall, there was no significant different in any of the innate cell populations studied, including neutrophils, monocytes (including G-MDSCs), macrophages (M1 of M2 phenotypes), and dendritic cells. B cells, CD8 effector T cells, CD4 T cells, Naive CD4 T cells, Th17 cells, and CD4 T cells with Th1-phenotypes s were all significantly increased in replaced knees compared to native knees (p < 0.02 in each case). The replaced knee group showed elevated levels of CXCL5, HGF, IFN-gamma, IL-6, IL-16, CXCL10, CCL2 (MCP-1), CCL8, MDC, TNF-alpha, and VEGF-A compared to the native knee group (p < 0.01 for all) and a decrease in CX3CL1, CXCL11, IL-3, IL-5, CXCL9, TRAIL (p < 0.02 in all cases). Conclusions Arthroplasty surgery results in a lymphocytic shift in immune cell populations and a generally pro-inflammatory cytokine/chemokine profile. Overall, this lymphocytic shift may have implications for development of periprosthetic infections and warrants further study.