Single-cell Transcriptomics Inference of Neutrophil-mast Cell Communication Programs in Periodontitis.

Neutrophil dysregulation is one of the main features of periodontitis (PD). This study delineated neutrophil heterogeneity and predicted potential communication of mast cells within the microenvironment of PD using computational single-cell transcriptomics. We analyzed a public scRNA-seq dataset (GSE171213) from gingival tissues of healthy controls, PD patients, and post-treatment patients. Data processing, clustering, and annotation were performed using Seurat and Harmony packages. Cell-cell communication was computationally inferred using CellChat and NicheNet packages, and transcriptional regulatory programs were predicted via SCENIC. HMC-1.2 mast cells were treated with TGFB1 and assessed for proliferation, migration, the level of VEGFA, IL-6, and TNF-α. Ten cell types in PD were identified. Two distinct transcriptional states of neutrophils were identified based on gene expression profiles. Cell-cell communication analysis predicted that Subtype 2, which was enriched for inflammatory and effector genes, exhibited stronger putative interactions with mast cells via ligand-receptor pairs such as IL6-(IL6R+IL6ST) and SEMA4D- PLXNB2. NicheNet-based analysis further inferred that neutrophil-derived TGFB1, OSM, and IL1B were associated with mast-cell target gene programs related to proliferation, migration, angiogenesis, and inflammatory responses. Finally, in vitro cell experiments indicated that TGFB1 inhibited proliferation but promoted migration and the expression of VEGFA, IL-6, and TNF-α. However, all effects were reversed by SB431542, confirming TGFBR1 dependence. This study delineated neutrophil transcriptional heterogeneity in PD and identified neutrophil- mast cell communication axes as a contributor to the inflammatory microenvironment in PD. Through computational analysis of single-cell transcriptomics, this study described two neutrophil states and their predicted interaction network with mast cells in PD, providing testable hypotheses for future mechanistic and translational studies.