Spatially resolved transcriptomics reveals pro-inflammatory fibroblast involved in lymphocyte recruitment through CXCL8 and CXCL10.

The interplay among different cells in a tissue is essential for maintaining homeostasis. Although disease states have been traditionally attributed to individual cell types, increasing evidence and new therapeutic options have demonstrated the primary role of multicellular functions to understand health and disease, opening new avenues to understand pathogenesis and develop new treatment strategies. We recently described the cellular composition and dynamics of the human oral mucosa; however, the spatial arrangement of cells is needed to better understand a morphologically complex tissue. Here, we link single-cell RNA sequencing, spatial transcriptomics, and high-resolution multiplex fluorescence in situ hybridisation to characterise human oral mucosa in health and oral chronic inflammatory disease. We deconvolved expression for resolution enhancement of spatial transcriptomic data and defined highly specialised epithelial and stromal compartments describing location-specific immune programs. Furthermore, we spatially mapped a rare pathogenic fibroblast population localised in a highly immunogenic region, responsible for lymphocyte recruitment through CXCL8 and CXCL10 and with a possible role in pathological angiogenesis through ALOX5AP. Collectively, our study provides a comprehensive reference for the study of oral chronic disease pathogenesis.

Expression of periodontitis susceptibility genes in human gingiva using single-cell RNA sequencing.

OBJECTIVE: Single-cell transcriptomics was used to determine the possible cell-type specificity of periodontitis susceptibility genes. BACKGROUND: The last decade has witnessed remarkable advances in the field of human genomics. Despite many advances, the genetic factors associated with or contributing to the periodontitis pathogenesis have only been identified to a limited extent and are often poorly validated. Confirming whether a given single nucleotide polymorphism has an association with periodontitis requires a robust mechanistic explanation on the functional consequences of a given genetic variant. METHODS: We globally assessed the expression of 26 disease-associated genes identified by GWAS within the gingival mucosa. A total of 12 411 cells from 4 different donors were analysed. Differentially expressed genes were analysed using Seurat, a non-parametric Wilcoxon rank sum test. The minimum threshold for significance was defined as p < .05. RESULTS: This exploration at a cellular-level suggests diverse populations contributing to disease pathogenesis, with macrophages expressing a higher number of the analysed disease-associated genes. IL1B, PTGS2, FCGR2A, IL10 and IL1A specifically showed a more restricted expression in the myeloid lineages. CONCLUSION: This short report combines human genetics and single-cell genomics to better understand periodontitis by mapping variants to predict their cells of action and putative functions. These findings seem to suggest that innate cell dysfunction is linked to disease susceptibility.

Defining human mesenchymal and epithelial heterogeneity in response to oral inflammatory disease.

Human oral soft tissues provide the first barrier of defence against chronic inflammatory disease and hold a remarkable scarless wounding phenotype. Tissue homeostasis requires coordinated actions of epithelial, mesenchymal, and immune cells. However, the extent of heterogeneity within the human oral mucosa and how tissue cell types are affected during the course of disease progression is unknown. Using single-cell transcriptome profiling we reveal a striking remodelling of the epithelial and mesenchymal niches with a decrease in functional populations that are linked to the aetiology of the disease. Analysis of ligand-receptor interaction pairs identify potential intercellular hubs driving the inflammatory component of the disease. Our work establishes a reference map of the human oral mucosa in health and disease, and a framework for the development of new therapeutic strategies.

Interaction of tea polyphenols and food constituents with model gut epithelia: the protective role of the mucus gel layer.

The luminal surface of the gastrointestinal tract is covered by a mucus gel layer that acts to protect gut epithelial cells from the harsh luminal environment. This study investigated the use of two human colonic adenocarcinoma cell lines, HT29-MTX-E12 and HT29, as a model to mimic gut epithelium with and without a mucus gel layer. The effect of adding the tea polyphenols epigallocatechin gallate (EGCG) and epicatechin (EC) to the cells with subsequent examination of cell morphology and viability was assessed. EGCG, at the concentrations tested, was very toxic to the HT29 cells, but less toxic to the HT29-MTX-E12 cells, suggesting that the mucus gel layer on the HT29-MTX-E12 cells can protect the cells against EGCG toxicity. In contrast, EC had no effect on the viability of either the HT29 or HT29-MTX-E12 cells, suggesting that proteins within the mucus gel layer on the apical surface of gut epithelial cells may bind to the galloyl ring of EGCG. The effect of adding food-related ingredients with the ability to complex with EGCG, ß-casein and maltodextrin, on cell viability was also examined. The presence of ß-casein was very effective in protecting the cells against the toxicity effect of EGCG, but maltodextrin, at the concentration tested, was less effective in protecting against this toxicity. In conclusion, the results demonstrate that the mucus gel layer on HT29 human colonic adenocarcinoma cells may protect these cells against EGCG toxicity. In addition, the data showing reduced toxicity of EC compared to that of EGCG suggest that the cytotoxic effects of high polyphenol levels may be associated with the ability of polyphenols to interact with cellular proteins and mucins.