A stitch of CD9 saves nine: CD9+ tissue-resident memory T cells in Sjogren's syndrome and autoimmunity.

This editorial underscores the role of CD9+ tissue-resident memory (Trm) cells in autoimmune diseases, specifically in Sjogren's syndrome, and points to potential implications for better understanding the nature of recurrent autoimmune flares. New findings from Chang et al. highlight the presence and functional role of CD8+ Trm cells in inflamed labial glands in Sjogren's syndrome patients. This, together with the noted expression of CD9 in these Trm cells, opens a new research avenue into the mechanistic understanding of autoimmune diseases. The editorial also emphasizes the need for further studies to answer pressing questions related to CD9+ Trm cell function and their role in autoimmune diseases.