Possible involvement of Toll-like receptor 8-positive monocytes/macrophages in the pathogenesis of Sjögren's disease

Sjögren's disease (SjD) is an autoimmune disease marked by lymphocytic infiltration of salivary and lacrimal glands, leading to glandular dysfunction, where CD4-positive helper T (Th) cells and their cytokines are crucial in the pathogenesis. Recent studies have demonstrated that Toll-like receptors (TLRs), particularly those recognizing immune complexes containing DNA and RNA, contribute to Th cell activation in various autoimmune diseases. This study explores the expression and function of these TLRs in SjD. In scRNA-seq analysis, the TLR8-expressing cluster comprised macrophages and monocytes, which also produced T cell activation genes like CD86, suggesting that infiltrating monocytes and macrophages may produce cytokines and chemokines through TLR8 stimulation, potentially enhancing B7 molecule expression, promoting the adaptive immune response, and contributing to SjD pathogenesis. CD45+ cells were isolated from a fresh SjD biopsy tissue sample obtained from surgery, and were loaded into a 10x Genomics Chromium device according to the protocol of Chromium Single Cell 5' Reagent Kits (v2).