Fig 2: Effect of IFNγ regulation of JAK/STAT1 signaling pathway on BAFF expression in pSS. A: Western blot assay for the effect of IFNγ (100 ng/mL) and JAK-specific inhibitor (PF-04965842) on the expression of p-JAK1, p-STAT1, and BAFF in MNC cells. B: dual luciferase assay to verify the effect of IFNγ (100 ng/mL) and JAK-specific inhibitor (PF-04965842) on BAFF promoter activity. C: ChIP experiments on the effect of IFNγ (100 ng/mL) and JAK-specific inhibitor (PF-04965842) on STAT1 enrichment in the BAFF promoter region. The measurements were expressed as means ± SD, and multiple comparisons were performed using one-way analysis of variance (ANOVA). **P < 0.01 compared between the two groups; ***P < 0.001 compared between two groups; ns denotes P > 0.05 compared between two groups; all experiments were repeated three times. BAFF, B-cell-activating factor; ChIP, chromatin immunoprecipitation; IFNγ, interferon-gamma receptor; JAK, Janus kinase; MNC, mononuclear cell; pSS, primary Sjögren’s syndrome; STAT1, signal transducer and activator of transcription 1.

Fig 3: Immunohistochemistry to detect the expression of various factors in the kidneys of patients with IgAN (magnification, ×400). In comparison with the healthy control group, the expression levels of BAFF, TRAF6, p-NF-κBp65, FN and CTGF were markedly increased in the kidneys of patients with IgAN. BAFF, B cell-activating factor; CTGF, connective tissue growth factor; FN, fibronectin; IgAN, IgA nephropathy; p-, phosphorylated; TRAF, tumor necrosis factor receptor-associated factor.

Fig 4: Clinical indicators of rats in the IgA nephropathy model group. A, con-siRNA; B, con-siRNA + IgA; C, BAFF-RFc chimera protein + IgA; D, TRAF6-siRNA + IgA. *P<0.05 vs. group A; ΔP>0.05 vs. group B; #P<0.05 vs. group B. BAFF, B cell-activating factor; siRNA, small interfering RNA; TRAF, tumor necrosis factor receptor-associated factor.

Fig 5: Expression of IFNγ and BAFF in pSS samples and their correlation with B-lymphocyte infiltration. A: differential analysis of IFN-γ mRNA expression in normal (n = 30) and pSS (n = 30) samples by microarray GSE84844. B: differential analysis of BAFF mRNA expression levels in normal (n = 30) and pSS (n = 30) samples by microarray GSE84844. C: the infiltration of lymphocytes in the exocrine gland tissues of normal control mice and pSS mice was observed using H&E staining at a magnification of 200 times (scale bar = 25 μm). D: immunohistochemical staining was performed to determine the positive expression rates of IFN-γ and BAFF proteins in the exocrine gland tissues of normal control mice and pSS mice at a magnification of 200 times (scale bar = 25 μm). E: the correlation between the expression of IFN-γ mRNA and BAFF mRNA was analyzed using the Pearson correlation coefficient method. F: the protein expression levels of IFN-γ in MNC cells isolated from the exocrine gland tissues of the Control group and pSS group were detected using ELISA and RT-qPCR. G: the protein expression levels of BAFF in MNC cells isolated from the exocrine gland tissues of the Control group and pSS group were detected using ELISA and RT-qPCR. H: Spearman hierarchical correlation analysis was performed to analyze the correlation between IFN-γ and the number of BAFF-positive cells and the number of B-lymphocyte infiltration foci; the quantitative data were represented using the means ± SD. The data between the two groups were compared using an independent t test. ***P < 0.001 compared between two groups; ns indicates P > 0.05 compared between two groups; all experiments were repeated three times; 10 mice per group mice. BAFF, B-cell-activating factor; ELISA, enzyme-linked immunosorbent assay; H&E, hematoxylin and eosin; IFNγ, interferon-gamma receptor; MNC, mononuclear cell; pSS, primary Sjögren’s syndrome; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.