Transcriptomic and Single-Cell Analysis Reveals Regulatory Networks and Cellular Heterogeneity in Mouse Primary Sjögren’s Syndrome Salivary Glands

Abstract

Sjögren’s Syndrome (SS) is a chronic autoimmune disease of unknown etiology which primarily affects the salivary and lacrimal glands resulting in the loss of secretory function. Treatment options for SS have been hampered due to the lack of a better understanding of the underlying gene regulatory circuitry and the interplay between the myriad pathological cellular states that contribute to salivary gland dysfunction. To better elucidate the molecular nature of SS, we have performed RNA-sequencing analysis of the submandibular glands (SMG) of a well-established primary Sjögren’s Syndrome (pSS) mouse model. Our comprehensive examination of global gene expression and comparative analyses with additional SS mouse models and human datasets, have identified a number of important pathways and regulatory networks that are relevant in SS pathobiology. To complement these studies, we have performed single-cell RNA sequencing to examine and identify the molecular and cellular heterogeneity of the diseased cell populations of the mouse SMG. Interrogation of the single-cell transcriptomes has shed light on the diversity of immune cells that are dysregulated in SS and importantly, revealed an activated state of the salivary gland epithelial cells that contribute to the global immune mediated responses. Overall, our broad studies have not only revealed key pathways, mediators and new biomarkers, but have also uncovered the complex nature of the cellular populations in the SMG that are likely to drive the progression of SS. These newly discovered insights into the underlying molecular mechanisms and cellular states of SS will better inform targeted therapeutic discoveries.

Spatial transcriptomics of the lacrimal gland features macrophage activity and epithelium metabolism as key alterations during chronic inflammation

“…We also noted the downregulation of several metabolic pathways (See square on Figure 3B ). These findings correlate with the recently published data on the RNA sequencing of the NOD.H-2b mouse submandibular glands ( 25 ) and with analysis of diabetic NOD mouse model ( 33 ). Taken together our data suggests an altered lipid homeostasis during LG inflammation.…”

“…One of the most unexpected findings was that activation of the inflammatory pathways was found in all epithelial cell clusters, suggesting that the epithelial compartments participate in the inflammatory process. The contribution of the epithelial cells to disease progression was reported for the SMG of the pSS mouse model and in patients with SS ( 25 , 82 ). Furthermore, corneal epithelial cells act as an initial physical and immunological barrier to injury/infection playing an important role in the immune response ( 83 ).…”

“…These mice show reduced lacrimal and salivary gland secretion, formation of mononuclear lymphocytic infiltrations, and the presence of the SSA and SSB antibodies ( 11 , 24 ). A recent study reported scRNA-seq analysis of the salivary submandibular glands (SMG) of the NOD.H-2b ( 25 ). This study identified inflammation-induced changes in multiple cell populations of the SMG, suggesting the complex nature of the cellular responses to chronic inflammation.…”

Single‐cell RNA sequencing in oral science: Current awareness and perspectives

“…The subsequent DEG and KEGG analysis demonstrated that affected acinar and ductal epithelial cell subpopulations may transition to a mixed epithelial/immune cell-like state by aberrantly expressing molecules associated with immune cells. 126 In addition, combined genome-wide association studies (GWASs) and RNA-seq data for Sjogren's syndrome with human parotid gland scRNA-seq results, susceptibility genes in human parotid glands were identified. 58 Systemic lupus erythematosus (SLE), a type of chronic and even life-threatening autoimmune disease, is characterized by obscure pathogenesis and diverse manifestations.…”

“…The scRNA‐seq was applied for detection on the diseased cell subpopulations and their expression profiles in primary Sjogren's Syndrome mouse salivary gland. The subsequent DEG and KEGG analysis demonstrated that affected acinar and ductal epithelial cell subpopulations may transition to a mixed epithelial/immune cell‐like state by aberrantly expressing molecules associated with immune cells 126 . In addition, combined genome‐wide association studies (GWASs) and RNA‐seq data for Sjogren's syndrome with human parotid gland scRNA‐seq results, susceptibility genes in human parotid glands were identified 58 …”