Origin of galactose-deficient immunoglobulin g in gingival crevicular fluid in periodontitis

The influence of microbiota on the development and course of inflammatory diseases of periodontal tissues

An important feature of the functioning of the organs and tissues of the oral cavity is the fact that all processes that take place in it are carried out in the constant presence of various microorganisms that cause the development of pathological processes in the body or are associated with them. In the pathogenesis of chronic generalized periodontitis, dental plaque penetrates the bottom of the gingival sulcus, penetrating under the epithelium into the stroma of the connective tissue, causing its inflammation. Bacteria produce a number of toxic substances that have a toxic effect on surrounding tissues. Most bacteria produce chain fatty acids that inhibit chemotaxis of leukocytes and phagocytes. Anaerobes and spirochetes secrete a number of substances (propionic acid and indole) that are extremely toxic to most tissues. Inflammation in the periodontal tissues is caused by the microbiota of the dental plaque biofilm. As periodontitis develops, an increase in the number of P. gingivalis, P. intermedia and T. forsythia was found in it, more than 100 times. Therefore, the given data prove that in the development and course of the inflammatory process in the periodontal tissues, complex dysbiotic and tissue-cellular interactions are involved, the dynamic balance of which depends on its outcome.

IL-6 and its role in IgA nephropathy development

IL-6 is considered one of the well characterized cytokines exhibiting homeostatic, pro- and anti-inflammatory activities, depending on the receptor variant and the induced intracellular cis- or trans-signaling responses. IL-6-activated pathways are involved in the regulation of cell proliferation, survival, differentiation, and cell metabolism changes. Deviations in IL-6 levels or abnormal response to IL-6 signaling are associated with several autoimmune diseases including IgA nephropathy (IgAN), one of most frequent primary glomerulonephritis worldwide. IgAN is associated with increased plasma concentration of IL-6 and increased plasma concentration of aberrantly galactosylated IgA1 immunoglobulin (Gd-IgA1). Gd-IgA1 is specifically recognized by autoantibodies, leading to the formation of circulating immune complexes (CIC) with nephritogenic potential, since CIC deposited in the glomerular mesangium induce mesangial cells proliferation and glomerular injury. Infection of the upper respiratory or digestive tract enhances IL-6 production and in IgAN patients is often followed by the macroscopic hematuria. This review recapitulates general aspects of IL-6 signaling and summarizes experimental evidences about IL-6 involvement in the etiopathogenesis of IgA nephropathy through the production of Gd-IgA1 and regulation of mesangial cell proliferation.