Department of Clinical Immunology & Rheumatology, Christian Medical College and Hospital Vellore, Vellore, India.
Department of Clinical Biochemistry, Christian Medical College and Hospital Vellore, Vellore, India.
Int J Rheum Dis. 2022 Jan;25(1):61-69. doi: 10.1111/1756-185X.14242. Epub 2021 Nov 17.
B cells contribute significantly to the pathogenesis of primary Sjögren's syndrome (pSS). Free light chains (FLCs) are generated during the production of immunoglobulins (Igs) and are surrogates of B cell activity. We hypothesized that salivary FLCs and salivary Igs could represent salivary gland inflammation and therefore, serve as biomarkers in pSS.
Patients >18 years old fulfilling the American College of Rheumatology / European League Against Rheumatism (EULAR) 2016 criteria for pSS and age-matched healthy and disease controls (sicca non-pSS, rheumatoid arthritis, systemic lupus erythematosus) were recruited for this cross-sectional study. FLCs in saliva and serum were measured by immunoturbidimetry. Serum and salivary Igs were measured by nephelometry and enzyme-linked immunosorbent assay, respectively. Area under the receiver operator characteristic curve was determined. The factors influencing the serum and salivary FLCs in pSS were determined using backward linear regression.
A total of 78 patients with pSS, 76 healthy controls and 62 disease controls were recruited. Median EULAR SS disease activity index (interquartile range) was 1 (3.75). Serum FLCκ and FLCλ, salivary FLCλ, serum and salivary IgG, salivary IgM was significantly higher in the pSS group compared to the controls. Areas under the curve for salivary FLCλ, serum FLCκ, serum and salivary IgG were 0.75, 0.72, 0.78 and 0.77, respectively. Regression analysis showed that salivary FLCκ, salivary FLCλ and salivary IgG were associated with positive salivary gland histopathology. Use of immunosuppressants and glucocorticoids was associated with lower values of salivary parameters.
Salivary FLCλ and salivary IgG were significantly different between pSS and control groups and could be potential non-invasive biomarkers in pSS. These findings should be confirmed in larger longitudinal studies.
B 细胞在原发性干燥综合征（pSS）的发病机制中起重要作用。游离轻链（FLC）在免疫球蛋白（Igs）产生过程中产生，是 B 细胞活性的替代物。我们假设唾液 FLC 和唾液 Ig 可以代表唾液腺炎症，因此可以作为 pSS 的生物标志物。
这项横断面研究招募了年龄在 18 岁以上，符合美国风湿病学会/欧洲抗风湿病联盟（EULAR）2016 年 pSS 标准且年龄匹配的健康对照和疾病对照（非干燥综合征的干燥患者、类风湿关节炎、系统性红斑狼疮）。采用免疫比浊法检测唾液和血清中的 FLC，用散射比浊法和酶联免疫吸附法分别检测血清和唾液中的 Ig。确定受试者工作特征曲线下的面积。采用向后线性回归法确定影响 pSS 患者血清和唾液 FLC 的因素。
共纳入 78 例 pSS 患者、76 例健康对照和 62 例疾病对照。EULAR SS 疾病活动指数（中位数[四分位数间距]）为 1（3.75）。与对照组相比，pSS 组血清 FLCκ和 FLCλ、唾液 FLCλ、血清和唾液 IgG、唾液 IgM 显著升高。唾液 FLCλ、血清 FLCκ、血清和唾液 IgG 的曲线下面积分别为 0.75、0.72、0.78 和 0.77。回归分析显示，唾液 FLCκ、唾液 FLCλ 和唾液 IgG 与唾液腺组织病理学阳性有关。免疫抑制剂和糖皮质激素的使用与唾液参数值较低有关。
pSS 组与对照组之间唾液 FLCλ和唾液 IgG 有显著差异，可能是 pSS 的潜在非侵入性生物标志物。这些发现应在更大的纵向研究中得到证实。
