Guardians on call: neutrophils, macrophages and dendritic cells in arthritis pathogenesis

Several immune/inflammatory components have been associated with arthritis. The role of monocytes/macrophages in inflammatory arthritis has been explored over the last years; however, the role of other myeloid cells, such as neutrophils and dendritic cells, in driving the pathophysiology of arthritis is largely overlooked. In this article, we aim to discuss literature pointing to the role of these immune cells in inflammatory arthritis and emphasize the multiple and dynamic phenotypic roles these cells can hold either in the persistence or in the resolution of inflammation. We also highlight the interactions between neutrophils, macrophages, and/or dendritic cells in the arthritic joint space. We further discuss pathways and features that may be of importance for characterizing neutrophils and dendritic cells, the phenotype of which can be "reprogrammed" to direct the resolution of inflammation efficiently in the arthritic joint. Identifying novel and patient-tailored approaches for addressing persistent or recurrent inflammation through these cellular pathways, might address unmet needs in arthritis management. Types of arthritides discussed in this review include osteoarthritis, spondyloarthritis and rheumatoid arthritis. Brief reference to the role of these immune cells in the acute gouty inflammation is also included.