Assessment of Galectin-9 in Rheumatoid Arthritis and Its Correlation With Disease Activity

Rheumatoid arthritis (RA) is an autoimmune disease in which a symmetrical Synovial inflammation, bone destruction occur in both small and big Joints. If left untreated, this illness does not generally cause death, but it does drastically affect the quality of life and life expectancy of patients. Although there is no cure for RA, patients are generally on long-term long-acting disease-modifying anti-rheumatic medications (DMARDs) to control joint inflammation, reduce joint damage, maintain joint function, and keep the illness in remission.

RA disease activity could be detected be DAS28 score. The DAS28 is a four-item scale that gives an absolute number reflecting disease activity. It includes the number of swollen and tender joints (SJC, TJC), the visual analogue scale of patients' assessment of their general health (VAS-GH), and the erythrocyte sedimentation rate (ESR) in the first hour.

In the pathophysiology of RA, cytokine networks play a crucial role. Rheumatoid inflammation has been linked to the generation of proinflammatory cytokines throughout time. Increased cytokine levels, such as tumour necrosis factor (TNF) and interleukin-6 (IL-6), represent rheumatoid synovial inflammation and have been linked to RA disease activity and anti-cytokine therapeutic response. The relationship between circulating cytokine levels and the phenotype of RA illness is, however, poorly understood.

Anti-citrullinated peptide antibodies (ACPA) are effective in the diagnosis of RA and have been linked to joint destruction progression and therapy response in RA patients. However, the relationship between ACPA status and proinflammatory cytokines during the course of RA illness is yet unknown.

Galectins are lectins with carbohydrate recognition domains (CRDs) that are extremely similar in sequence and exclusively bind to β--galactoside carbs. There are at least 15 galectins found in mammals, each having one or two CRDs comprising roughly 130 amino acids. Galectins have a wide range of activities due to their ubiquitous distribution, including mRNA splicing, programmed cell death, cell cycle control, activation, adhesion, migration, and cell differentiation.

Galectin-9 (Gal-9) is abundantly present in lymph nodes, bone marrow, liver, thymus, and spleen. It is expressed by immune cells, endothelial cells, and fibroblasts and plays an important role in regulating inflammation and immune reactions. Gal-9 is a ligand for T cell immunoglobulin and mucin-containing-moleculte-3 (Tim-3) that is expressed on CD4+ T helper (Th) 1 and Th17 and sends inhibitory signals to Tim-3. As a result of its interaction with Tim-3, Gal-9 suppresses pro-inflammatory T cell responses, and the Gal-9/Tim-3 pathway causes apoptosis of CD4+ Th1 or Th17 cells.

Considering that RA is a Th1-polarized autoimmune illness, dysregulated Gal-9 levels may induce an innate/adaptive immunity imbalance, resulting in pathological rheumatoid inflammation. Gal-9 has been demonstrated to mediate angiogenesis and inflammatory cell infiltration in inflammatory arthritis.

These findings show that Gal-9 may have a role in the inflammatory processes of rheumatoid arthritis. As a result, we concentrated on Gal-9 and postulated that it could be involved in the pathogenesis of RA. The levels of serum Gal-9 in individuals with RA were studied in this study, and the results were compared to clinical indicators