Serum IL 26 as a Marker of Disease Activity in SLE

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease characterized by diverse autoantibodies and varied clinical manifestations(mainly targeting the skin, kidneys, and brain). Autoantibodies directed against double-stranded (ds) DNA play a key role in the initiation and maintenance of inflammatory lesions in SLE(1).

Pathogenesis of SLE is mirrored by its complex aetiopathogenesis as genetic factors , environmental triggers (exposure to sunlight, drugs and infections, particularly with Epstein-Barr virus. . Causing secretion of inflammatory mediators , antibody and cytokines . But still pathological mechanisms of SLE are still not fully understood. (2) Immune system dysregulation such as incomplete clearance of apoptotic materials, hyperactivation of immune cells, overproduction of antibodies and abundant immune complex deposits are prominent in SLE (3) Clinical manifestations of SLE are Malar rash, Discoid rash ,Photosensitivity, Oral or nasopharyngeal ulcers, Pleurisy, Renal abnormalities, Immunologic abnormalities, Nonscarring alopecia, Synovitis, Hemolytic anemia, Leukopenia, Thrombocytopenia Proteinuria Seizures Psychosis Serositis and Arthritis (4) IL-26 is a 171-amino acid protein that belongs to the IL-10 family of cytokines, a family that includes IL-10, IL-19, IL-20, IL-22 and IL-24 . The IL-26 protein is encoded by the IL26 gene located on chromosome 12q15 between genes for interferon (IFN)-γ and IL-22 , and is conserved in several vertebrate species but not in mice and rats . The cytokine IL-26 was originally named AK155(5) IL-26 was initially identified as a pro-inflammatory cytokine , inducing the production of inflammatory cytokines by myeloid cells that are involved in the differentiation of naïve CD4+ T cells into Th17 cells (6) The involvement of IL 26 in numerous chronic auto inflammatory diseases and in two major pathogenic processes in SLE, namely the induction of IFN I and its production by Th 17 lymphocytes, makes the analysis of its role in SLE essential (7) Brilland et al., 2021 report that the levels of IL 26 are higher in SLE patients than healthy subjects and show a significant correlation with disease activity