THE IMPACT OF INTERLEUKIN-10 PROMOTER METHYLATION IN THE PATHOGENESIS OF SYSTEMATIC LUPUS ERYTHEMATOSUS IN IRAQI PATIENTS Yasmin Taha 1 *, Luma Hassan Alwan Al Obaidy 1 and Ali Hafedh Abbas 2 1 Department of Biology, College of Science for Woman, University of Baghdad, Baghdad, Iraq. 2 Tropical-Biological Research Unit, College of Science, University of Baghdad, Baghdad, Iraq. *e-mail : yasmin.taha1202a@csw.uobaghdad.edu.iq (Received 11 April 2021, Revised 9 June 2021, Accepted 19 June 2021) ABSTRACT : Interleukin -10 is an anti-inflammatory, T regulatory cytokine, produced by several activated immune cells and it has vital role in the suppression of the immune response via downregulation of the Th1, antigen presenting cells, and inflammatory cytokines production, as well as activation of B cell proliferation, differentiation and antibody production. Epigenetic modifications of the promoter of interleukin-10 controls its expression in the immune cells. Methylation of CG sequences within the promoter may play a crucial role in the induction of the chronic status of the SLE. Peripheral blood samples were collected from 60 patients had SLE (30 arthritis SLE and 30 nephritis SLE) and 30 apparently healthy controls. Interleukin-10 levels were assessed in the sera of the studied groups by ELISA technique, then DNA were extracted from whole blood and the methylation of interleukin promoter were analyzed by Real time-PCR technique. The serum level of interleukin-10 was significantly increased in SLE arthritis and nephritis patients’ groups compared to controls (23.46 ± 20.37 pg/ml and 28.23 ± 22.83 pg/ml vs. 16.03 ± 5.70 pg/ml, respectively). Also, the results were significantly higher in hypermethylation status of arthritis and nephritis SLE patients’ groups compared to the control group (29.98±23.52 and 41.52 ± 22.27 vs. 14.44 ± 3.88, respectively). As well as, a significant difference was shown in hypomethylated status of arthritis and nephritis SLE patients’ groups compared to the control group (25.70 ± 13.06 and 26.51±10.5 vs. 11.79 ± 5.11, respectively). In conclusion, in this study the results of IL-10 level were increased in SLE patients, there were no significant differences between hypermethylation and hypomethylation status of the IL-10 promoter when compared between SLE patients and healthy controls. Key words : Interleukin-10, promoter methylation, systemic lupus erythematosus, auto-antibodies, hypermethylation, hypomethylation. How to cite : Yasmin Taha, Luma Hassan Alwan Al Obaidy and Ali Hafedh Abbas (2022) The impact of Interleukin-10 promoter methylation in the pathogenesis of systematic lupus erythematosus in Iraqi patients. Biochem. Cell. Arch. 22, 2327-2331. DocID: https://connectjournals.com/03896.2022.22.2327 Biochem. Cell. Arch. Vol. 22, No. 1, pp. 2327-2331, 2022 www.connectjournals.com/bca ISSN 0972-5075 DocID: https://connectjournals.com/03896.2022.22.2327 eISSN 0976-1772 INTRODUCTION The cytokine’s have a crucial role in systemic lupus erythematosus (SLE) is in controlling the immune response and inflammation process in health and disease (Marques et al, 2016). They control the immune response and they work synchronously in a complex network of signaling mediator to govern the pro-inflammatory and anti-inflammatory process (Rahimifard et al, 2017). Functionally, they were divided into several types according to their cellular communications into interleukins, chemokines, or growth factors (Khan, 2019). Interleukin-10 (IL-10) is one of the anti-inflammatories and T cell regulatory cytokine that produces by T CD4 cells, activated B cells, mast cells, macrophages, keratinocytes and monocytes, and it has vital role in the suppression of the immune response via downregulation of the Th1, antigen presenting cells, and inflammatory cytokines production, as well as activation of B cell proliferation, differentiation and antibody production (Beebe et al, 2002). In other hand , increasing evidences indicate that IL-10 plays an important role in both the onset and development of auto-immune diseases, such as Systemic Lupus Erythematosus (SLE), Rheumatoid arthritis (RA) and Psoriasis (Wang et al, 2013). In human, IL-10 gene occupy the band 1q32 on chromosome 1, it has 5 exons that encode 37 kDa homodimer molecule, each monomer with 160 amino acids. The level of serum IL-10 is controlled by the prompter of the IL-10 gene (Marlow et al , 2013). Evolutionary several genetic verities (SNP) and epigenetic