Objective:To investigate the expression of cGAS-STING signaling pathway molecules in labial gland specimen of primary Sj?gren′s syndrome (pSS) patients and its correlation with disease characteristics.Methods:Clinical data and labial gland specimens were collected from 19 patients diagnosed with pSS who visited Xuanwu Hospital, Capital Medical University, from January 2021 to December 2021, along with a control group of 7 gender-and age-matched individuals with isolated xerostomia.We performed immunofluorescence staining for cGAS on labial gland specimens, and Western blot analysis was further utilized to confirm the expression levels of cGAS-STING signaling pathway-related molecules (cGAS, pSTING, pIRF3 and pTBK1) in the labial gland tissues of both groups. For normally distributed data, t test was employed for comparison between groups, while the Mann-Whitney U test was used for non-normally distributed data. And Spearman's correlation analysis was utilized to explore the correlation between clinical characteristics and molecular expression levels. P value<0.05 was considered statistically significant. Results:Immun-ofluorescence analysis showed significant infiltration of cGAS-positive cells in the labial gland tissues of the pSS group, while the control group exhibited no or minimal expression of cGAS-positive cells and there was a statistical difference between the two groups ( t=3.87, P=0.001). Moreover, the expression level of cGAS in labial gland tissues of pSS patients had a positive correlation with the focus scores ( r=0.55, P=0.014). Western blot analysis revealed statistically significant differences in the expression of cGAS and pSTING between the pSS group and the control group in labial gland tissues (0.73±0.39 vs. 0.18±0.05, t=2.38, P=0.049 and 0.91±0.17 vs. 0.23±0.10, t=2.17, P=0.043). Additionally, a correlation between the expression levels of cGAS and pSTING in labial gland tissues was found according to Spearman correlation analysis ( r=0.823, P=0.001). However, there was no correlation between the expression level of cGAS in labial gland tissues and clinical features, serological indicators (IgG level, titer of rheumatoid factor, C3 level and autoantibody positive rate) or disease activity (EULAR Sj?gren′s syndrome disease activity index scores). Conclusion:The cGAS-STING signaling pathway is activated in the labial gland tissue of pSS patients, which may be involved in its pathogenesis.