Rare Auto-immune Diseases

The pathophysiology of certain inflammatory arthritides remains poorly understood, particularly when associated with rare systemic autoimmune diseases such as systemic sclerosis (SSc), or when emerging in the context of immune-related adverse events from cancer immunotherapies. These immunotherapy-induced arthritides represent a new and increasingly encountered clinical entity in rheumatology. A deeper understanding of the mechanisms underlying joint inflammation in these settings is essential for identifying specific therapeutic targets, especially given the limitations of current treatment options and the risks associated with broad immunosuppressive strategies such as prolonged corticosteroid use, which may impair anti-tumor immune responses. Synovial biopsy analysis provides a powerful tool for dissecting the cellular and molecular components of joint inflammation, including immune cell infiltration, cytokine profiles, and cell-cell interactions. Advances in high-dimensional techniques such as multiplex immunofluorescence and mass cytometry now allow for the identification and spatial localization of numerous protein markers at the subcellular level. Additionally, spatial tran