RNA-Seq analysis of lymphocyte-specific gene expression patterns in IgG4-related disease: comparison of submandibular glands and peripheral blood.

OBJECTIVE

To clarify T/B cell-specific gene expression patterns using RNA-Seq in IgG4-related disease (IgG4-RD).

METHODS

Pathologically confirmed submandibular gland (SMG) (n = 3) and peripheral blood mononuclear cells (PBMC) (n = 4) from four treatment-naïve patients with definite IgG4-RD, as well as PBMCs from primary Sjögren syndrome (pSS) (n = 3) and healthy controls (HCs) (n = 3), were collected, and subsequently Pan T and CD19+ B cells were sorted. We conducted RNA sequencing to compare the gene expressions of Pan T and CD19+ B cells in SMGs and PBMCs in IgG4-RD or IgG4-RD versus pSS and HCs in PBMCs. Ingenuity pathway analysis (IPA) and qPCR validation were performed for differentially expressed genes (DEGs).

RESULTS

Principal component analysis (PCA) results showed the gene expression patterns of Pan T and CD19+ B cells derived from SMGs differed from those derived from PBMCs in IgG4-RD. However, the gene expression patterns of Pan T and CD19+ B cells derived from PBMCs were not clustered between groups. A total of 214 upregulated and 50 downregulated DEGs in Pan T cells and 630 upregulated and 109 downregulated DEGs in CD19+ B cells were identified in SMGs compared with PBMCs in IgG4-RD. The upregulated DEGs in SMGs of IgG4-RD included cytokines, chemokines, and transcription regulators. IPA for these DEGs clarified immune system-related pathways were positively regulated in SMGs compared with PBMCs in IgG4-RD. Quantitative PCR validated significantly increased mRNA expression of IL-21 and EGR2 by Pan T cells in SMGs compared with PBMCs of IgG4-RD.

CONCLUSION

RNA-Seq clarified the DEGs of Pan T and CD19+ B cells from SMGs in comparison with PBMCs, which might contribute to the pathogenesis of IgG4-RD.