Transcriptomic Mapping for Human Parotid Gland at Single-Cell Resolution

As the largest salivary gland in oral cavity, the parotid gland plays an important role in initial digesting and lubricating food. The abnormal secretory function of parotid gland can lead to dental caries and oral mucosal inflammation. In recent years, single-cell RNA sequencing (scRNA-seq) has been used to explore the heterogeneity and diversity of cells in various organs and tissues. However, the transcription profile of human parotid gland at single-cell resolution has not been reported yet. In this study, we constructed the cell atlas of human parotid gland using 10x Genomics platform. Characteristic gene analysis identified the biological functions of serous acinar cell populations in secreting digestive enzymes and antibacterial proteins. We revealed the specificity and similarity of parotid gland comparing to other digestive glands through comparative analyses of other published scRNA-seq datasets. We also identified the cell-specific expression of hub genes for Sjogren's syndrome in human parotid gland by integrating the results of GWAS and bulk RNA-seq, which highlighted the importance of immune cell dysfunction in parotid Sjogren's syndrome pathogenesis. Overall design: After the parotid gland sample was obtained, it was stored in tissue preservation solution (Miltenyi) at 4? and transferred to the laboratory. To obtain a qualified single-cell suspension, the parotid gland tissue was cut into small pieces of 1 mm3, and digested in collagenase (1mg/mL) and dispase (1 mg/mL) by shaking of 200 rpm at 37°C for 45 minutes. Dead cell removal magnetic beads (Miltenyi) were used to remove dead cells and cell debris. The cell suspension was centrifuged and resuspended in Ca2+ and, Mg2+ free PBS to reach a cell concentration of 900-1500cell/µL. Approximately 20,000 cells were loaded. cDNA library was constructed using 10x Chromium single cell v3.1 reagent, and sequenced on the Illumina Nova-seq system.