Identification and validation of necroptosis-related genes in peripheral blood mononuclear cells of Sjögren disease.

Background: Necroptosis has been implicated in multiple inflammatory and autoimmune disorders. However, its role in Sjögren disease (SjD) remains elucidated. In the current study, we aimed to identify and validate SjD-associated necroptosis genes. Methods: Differentially expressed genes were analyzed with GSE48378 downloaded from the GEO database using the DESeq2 R package. GO enrichment analysis and KEGG pathway enrichment analysis were carried out. Then, the necroptosis-relevant genes were subjected to PPI analysis. RT-PCR was used to verify the expression of the top 8 and the key 2 necroptosis genes, as well as HMGB1 expression. ELISA detected the concentration of HMGB1. The correlations of MLKL or HMGB1 with clinical parameters of SjD were also evaluated. The electron microscope confirmed whether necroptosis had occurred or not. Results: Twenty-four necroptosis-related genes were found in the PBMCs from SjD patients, all closely interacting as determined by PPI analysis. We established a validation cohort and selected the top eight differential necroptosis genes and two critical necroptosis genes from 24. We found that 7 of 10 (TNFRSF10, STAT3, NLRP3, RIPK, MLKL, TLR4, and EIF2AK2) were elevated in SjD, consistent with the bioinformatics analysis. We also found that HMGB1 levels in the peripheral blood of SjD were elevated and positively correlated with ESSDAI. Meanwhile, we found that the morphological features of cell death observed in PBMCs were consistent with those described for necroptosis in the PBMC of the SjD. Conclusion: The bioinformatics analysis identified an enrichment of the necroptosis pathway in the PBMCs of SjD, which was validated in a real-world cohort. Meanwhile, we found that HMGB1 levels were increased in peripheral blood and hypothesize that this elevation may be partly attributable to pyroptosis, despite the current lack of more substantial evidence. HMGB1 is also positively correlated with ESSDAI, suggesting that it may represent a novel therapeutic target.