Stem and progenitor cells that contribute to tissue repair reside within various niches in the synovial joints of adult mammals. Understanding of the origins, identities and functions of these cells will guide the development of pro-regenerative therapeutic strategies.

Hasegawa et al. reveal how synovial joints detect systemic inflammation through specialized fenestrated blood vessels at the synovial periphery. Three distinct macrophage populations and nociceptor neurons form a sentinel unit around these vessels, coordinating immune responses and pain signalling through interleukin-1β (IL-1β) and calcitonin gene-related peptide (CGRP) signalling.

Advances in spatial omics, such as transcriptomics and proteomics, have provided vital insights into cartilage microenvironments, revealing cellular diversity, zonal organization and links between cartilage structure and function. Analysing cartilage using spatial omics could deepen the understanding of diseases such as osteoarthritis and guide the development of targeted, disease-modifying therapies.

Neutrophil extracellular traps might promote intraocular infiltration of effector CD4⁺ T cells by inducing endothelial cell senescence in autoimmune uveitis.

Findings show that the resolution of joint swelling in response to treatment with TNF inhibitors varies depending on the location of the joint in psoriatic arthritis.

Two studies provide insights into the function of TASL in the pathogenesis of systemic lupus erythematosus and highlight the therapeutic potential of targeting this protein.

Advances in spatial omics, such as transcriptomics and proteomics, have provided vital insights into cartilage microenvironments, revealing cellular diversity, zonal organization and links between cartilage structure and function. Analysing cartilage using spatial omics could deepen the understanding of diseases such as osteoarthritis and guide the development of targeted, disease-modifying therapies.

Research demonstrates that the SARS-CoV-2 protein ORF8 drives osteoclastogenesis, establishing a direct link between viral infection and bone loss.

A mouse model that reflects Sjögren disease in humans provides insights into the role of regulatory T cells and type 1 helper T cells in disease pathogenesis.