M1 macrophage and Treg crosstalk mapping at single-cell resolution in mucosal chronic graft-versus-host disease 3940

Description Chronic Graft-Versus-Host Disease (cGVHD) is an alloimmune disorder caused by antigen mismatches during allogeneic hematopoietic stem cell transplant. The oral mucosa (OM), a primary site of tissue damage in oral cGVHD, is frequently affected, presenting with lymphocyte infiltration, ulceration, hyperkeratosis, fibrosis, and erythema. However, cellular interactions and spatial organization driving cGVHD are poorly understood. Single-cell RNA sequencing (scRNA-seq) revealed an increased frequency of macrophage (MF) subsets in the OM of cGVHD patients. Spatial transcriptomics confirmed the enrichment of CD68+ MF near the basement membrane. Ultrahigh-plex spatial phenotyping further identified a significant increase in inflammatory (M1) MF, characterized by the expression of HLA-DR, CD86, and CXCL10, and elevated IL-17 production within affected tissues. IL-17 likely contributes to M1 MF recruitment and activation, further amplifying the inflammatory cascade. Spatial proximity analysis also revealed a significant association between M1 MF and CD4+ T-regulatory cells (Tregs) in unaffected GVHD. In cGVHD, this interaction appears to be weaker, with an insufficient presence of TIGIT+ Tregs, emphasizing the importance of their crosstalk in maintaining immune homeostasis and preventing tissue damage. Understanding the interplay between M1 MF and Tregs is critical for identifying therapeutic targets to manage oral cGVHD and restore immune balance.