Reviewer #2 (Public Review): Mouse gingival single-cell transcriptomic atlas: An activated fibroblast subpopulation guides oral barrier immunity in periodontitis

Abstract

Chronic cardiovascular and metabolic diseases have been linked with oral inflammation in the tooth-supporting gingiva. Therefore, elucidating the mechanisms underlying development of gingival inflammation may hold critical insight into the pathogenesis of these debilitating non-communicable diseases. Here, we report a unique fibroblast subpopulation activated to guide oral inflammation (AG fibroblasts), identified in a single-cell RNA sequencing-based gingival cell atlas constructed from the mouse ligature-induced periodontitis model. Collagen-XIV-positive AG fibroblasts localized beneath gingival epithelium express chemokine ligands and Toll-like receptor-related molecules upon ligature placement, which were linked to receptors expressed by neutrophils and lymphocytes, including innate lymphoid cells (ILCs). We further identify ILCs as the primary source of proinflammatory interleukin-17 cytokines and show that cervical alveolar bone resorption is absent in Rag2-/-γc-/-, but not Rag2-/-, mice suggesting ILC3s mediate the human periodontitis-like phenotype. We therefore propose AG fibroblasts function as a previously unrecognized surveillant to orchestrate chronic gingival inflammation in periodontitis.