Clinicopathological, Immunohistochemical CXCL10, CXCR3, Serum IL-35, IL-39 Analysis, and Bacterial Identification in...

Sjögren syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of the salivary and lacrimal glands. The CXCL10-CXCR3 axis is considered central in promoting inflammation and damaging the gland, while oral microbial dysbiosis may amplify immune activation.

This is a cross-sectional case-control study in which 37 patients who met the 2016 ACR-EULAR criteria and 17 age- and sex-matched healthy controls were recruited at the College of Dentistry, University of Baghdad. Oral sample was cultured on selective media to characterize oral bacteria, serum IL-35 and IL-39 levels were quantified by ELISA, and labial salivary gland biopsies from patients underwent histopathology and CXCL10/CXCR3 immunohistochemistry.

Patients showed a pronounced systemic imbalance in cytokines, with reduced IL-35 and increased IL-39, significantly different from controls, and a highly decreased IL-35/IL-39 ratio (all P<0.001). The receiver operating characteristic curve analysis revealed high sensitivity, specificity, and overall efficiency for IL-35 (AUC=0.933), IL-39 (AUC=0.956), and the ratio (AUC=0.983). Immunohistochemistry of the labial salivary glands revealed generalized overexpression of CXCL10 and CXCR3 (all P<0.001) in patients. Oral microbiologic evaluation revealed increased Lactobacillus (Rogosa) and significant selective growth of Gram-positive cocci, Gram-negative bacilli (P=0.003). No correlation with disease activity, ESR was evident.

This research has revealed that patients with pSS have a noticeable shift in the immune response, characterized by decreased IL-35, increased IL-39, and increased CXCL10-CXCR3, simultaneously with changes in the oral microbiota. Future research with a more precise research design, a larger population, and the use of modern microbiota analysis is required.