OBJECTIVE: To create a comprehensive multi-tissue molecular atlas of Sjögren's disease by using unbiased RNA sequencing to identify differentially expressed genes (DEGs) in peripheral blood and conjunctival transcriptomes, and to characterize the ocular surface and gut microbiome profiles in participants classified as Sjögren's versus non-Sjögren's disease.

METHODS: This exploratory study used high-throughput RNA sequencing to analyze peripheral blood, conjunctival swabs, and rectal swabs from participants (11 classified as Sjögren's disease and four classified as non-Sjögren's) to identify DEGs and microbial profiles that could distinguish these groups.

RESULTS: Differential gene expression analysis revealed upregulated type I interferon (IFI44L, OASL, USP18) and complement pathways (SERPING1) in peripheral blood, alongside activation of several novel pathways in the conjunctiva including intracellular vesicle trafficking (HIP1, GOLIM4, FIG4), immunometabolism (CERS5, HPRT1, ULK2), and cytoskeletal remodeling (MARK1, IQCB1) in Sjögren's disease. In addition, distinct gut microbiome compositions were observed in Sjögren's disease participants, characterized by an increased presence of Lactobacillus reuteri species.

CONCLUSIONS: Using unbiased RNA sequencing, we confirmed the role of type I interferon and complement pathways in the peripheral blood and identified novel molecular signatures in the conjunctiva of Sjögren's disease participants. These newly identified pathways-involved in intracellular vesicle trafficking, immunometabolism, and cytoskeletal remodeling-expand our understanding of disease mechanisms beyond traditional immune pathways. In addition, we found distinct gut microbial profiles in Sjögren's disease participants, although ocular surface microbiome showed no significant differences. Such findings may suggest possible new therapeutic targets and allow for Sjögren's disease patient stratification. However, validation in larger cohorts is needed to establish clinical significance and potential applications in Sjögren's disease.