About this Research Topic
In recent years, understanding of macrophage biology has increased, highlighting previously unknown complexities and functional heterogeneity. It is now known that macrophages may arise either during embryogenesis from early myeloid progenitors or throughout life from bone-marrow derived monocytes. Moreover, macrophages are highly influenced by their tissue environment or ‘niche’. These myriad signals can direct macrophages towards a variety of functions including promoting inflammation, phagocytosis, wound healing, angiogenesis, and fibrosis. These functions can alternately contribute to or resolve pathogenesis. One such tissue that comprises a complex macrophage compartment is the synovium. In steady state, synovial macrophages maintain joint homeostasis by reinforcing synovial integrity and repairing mechanical damage. In contrast, arthritis results when protective subtypes become outnumbered by inflammatory cells contributing to joint damage and pain.
Macrophages are a known contributor to pathology in both rheumatoid and osteoarthritis, however the heterogeneity of synovial macrophages make targeting pathogenic populations problematic. Up to seven distinct macrophage populations have been described in recent studies, corresponding with disease stage, response to treatment, and specific aspects of pathology. To date, it is not fully understood how these populations contribute to or protect against pathology. To that end, in order to fully understand the pathology of arthropathies, it is essential to understand the synovial macrophage compartment and elucidate the contributions of these heterogeneous populations and how they may be modulated in treatment. Recent developments in single-cell sequencing, and spatial transcriptomic technologies enable more complex phenotyping of these populations even in small numbers, such as those available from synovial biopsies. The goal of this Research Topic is to elucidate the functional contributions of synovial macrophages in relation to, their direct protective or pathogenic functions in the synovium, impact on other immune and non-immune cells, potential for therapeutic targeting, and response to therapy.
This Research Topic accepts Original Research, Systematic Review, Methods, Review and Mini-Review, Policy and Practice Reviews, Hypothesis & Theory, Clinical Trial, Classification, Technology and Code, Study Protocol, Perspective, Case Report, Conceptual Analysis, Curriculum, Instruction, and Pedagogy, Brief Research Report, Data Report, General Commentary, Opinion.
We welcome manuscripts focusing on, but not limited to, the following sub-topics:
• Fundamental synovial macrophage biology and related cells
• Functional assays applied to synovial macrophages
• Comparisons of synovial macrophages across conditions
• The effect of arthritis therapies on synovial macrophages and correlations with patient outcomes
• The potential role for synovial macrophages in targeted therapeutic approaches
• Interactions between synovial macrophages and other immune cell types
• Contribution of synovial macrophages to the wider synovial compartment, e.g. activation of fibroblasts, secreted molecules, mechanical stresses, tissue degradation etc.
Macrophages are a known contributor to pathology in both rheumatoid and osteoarthritis, however the heterogeneity of synovial macrophages make targeting pathogenic populations problematic. Up to seven distinct macrophage populations have been described in recent studies, corresponding with disease stage, response to treatment, and specific aspects of pathology. To date, it is not fully understood how these populations contribute to or protect against pathology. To that end, in order to fully understand the pathology of arthropathies, it is essential to understand the synovial macrophage compartment and elucidate the contributions of these heterogeneous populations and how they may be modulated in treatment. Recent developments in single-cell sequencing, and spatial transcriptomic technologies enable more complex phenotyping of these populations even in small numbers, such as those available from synovial biopsies. The goal of this Research Topic is to elucidate the functional contributions of synovial macrophages in relation to, their direct protective or pathogenic functions in the synovium, impact on other immune and non-immune cells, potential for therapeutic targeting, and response to therapy.
This Research Topic accepts Original Research, Systematic Review, Methods, Review and Mini-Review, Policy and Practice Reviews, Hypothesis & Theory, Clinical Trial, Classification, Technology and Code, Study Protocol, Perspective, Case Report, Conceptual Analysis, Curriculum, Instruction, and Pedagogy, Brief Research Report, Data Report, General Commentary, Opinion.
We welcome manuscripts focusing on, but not limited to, the following sub-topics:
• Fundamental synovial macrophage biology and related cells
• Functional assays applied to synovial macrophages
• Comparisons of synovial macrophages across conditions
• The effect of arthritis therapies on synovial macrophages and correlations with patient outcomes
• The potential role for synovial macrophages in targeted therapeutic approaches
• Interactions between synovial macrophages and other immune cell types
• Contribution of synovial macrophages to the wider synovial compartment, e.g. activation of fibroblasts, secreted molecules, mechanical stresses, tissue degradation etc.
Keywords: Rheumatoid arthritis, osteoarthritis, biologics, macrophage heterogeneity, synovial niche
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.
