1. Putative contribution of tissue-specific (signal 1) and the local polarisation environment (signal 2) to the phenotype of synovial tissue macrophages in homeostasis and inflammation.
Putative contribution of tissue-specific (signal 1) and the local polarisation environment (signal 2) to the phenotype of synovial tissue macrophages in homeostasis and inflammation. Tissue-specific cues (signal 1), for example, from stretched synovial fibroblasts (FLS) to macrophage precursors may induce the synovial tissue macrophage programme that maintains synovial homeostasis. In the inflamed RA synovium, tissue-specific cues are modulated by proinflammatory on-demand signals (signal 2; eg, provided by epigenetically changed FLS, leucocytes and hypoxia). Most understanding is based on experimental models, and it is unknown whether distinct human synovial tissue macrophage subpopulations would respond differently to the synovial tissue-specific and ‘on-demand’ proinflammatory cues. Dissecting these pathways will improve our understanding of the mechanisms of successful versus failed joint homeostasis. MC, mast cells; ; MQ, macrophages; Neu, neutrophils; TF, transcription factor; Th17/Th1, T helper 1 and 17.
Mariola Kurowska-Stolarska, and Stefano Alivernini RMD Open 2017;3:e000527
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