The study of B-cell activating factor and a proliferation inducing ligand in the pathogenesis of primary Sjǒgren's syndrome / 中华风湿病学杂志

ABSTRACT

ObjectiveTo study B-cell activating factor(BAFF)/a proliferation inducing ligand (APRIL)protein and mRNA expression levels in patients with primary Sj(o)gren's syndrome(pSS)and its contribution to the pathogenesis of pSS.Methotis The levels of serum BAFF and APRIL were tested by ELISA method in 32 pSS patients and compared with 23 healthy control sabjects.BAFF/APRIL protein levels of labial salivary glands were examined in 17 pSS patients by immunohistochemical staining and compared with 8 healthy controls.BAFF/APRIL mRNA expression relative levels to GAPDH of PBMC were also detected in 18 pSS patients by real time RT-PCR and compared with 20 healthy controls.The relationship between BAFF/APRIL levels and several clinical manifestations in pSS patients were analyzed.Results The median level of serum BAFF in pSS were markedly higher than that in healthy controls[(7.4±3.9)ng/ml vs(3.7±1.1)ng/ml,P＜0.01].Serum APRIL levels were also significantly elevated compared to healthy controls[(26±15)ng/ml vs(16±15)ng/ml,P=0.039].The higher levels of BAFF were associated with higher levels of IgG,ESR.total globulin and the titer of ANA(P＜0.05).There was a positive correlation between serum APRIL levels and ESR and labial salivary gland lymphocyte focus scores(P＜0.05).The two cytokines levels inversely correlated with the count of peripheral white blood cells and platelets in pSS(P＜0.05).When comparing serum Ievels of APRIL and BAFF in patients with pSS,a positive correlation could be found(r=0.534,P=0.002).The BAFF/APRIL protein levels were higher in infiltrating lymphocytes of labial salivary glands from pSS patients than from the controls(P＜0.05).The BAFF mRNA[(0.023±0.024)vs(0.245±0.188),P＜0.01]and APRIL mRNA[(0.047±0.035)vs(0.130±0.097),P=0.002]levels of PBMC were significantly lower in pSS patients than in the normal controls.Conclusion The BAFF/APRIL levels of serum and labial salivary glands are significantly elevated in patients with pSS and correlate with clinical parameters.These indicate that BAFF and APRIL may be involved in the pathogenesis of pSS.The low BAFF mRNA and APRIL mRNA levels of PBMC in pSS may reveal that the production and regulation of this system is complicated.