Investigation of the relationship between serum LL-37 levels and disease activity in patients with behcet's disease

Behçet's disease (BD) is a systemic vasculitis characterized by mucocutaneous, ocular and articular symptoms as well as central nervous system, vascular and gastrointestinal involvement. It may cause morbidity and mortality due to systemic involvement. Although genetic, environmental and immunological factors play a role in the pathogenesis, the pathogenesis is not clear. There is no definitive treatment of Behcet's disease. There are no specific biomarkers that show disease progression and treatment response. Therefore, better understanding of the mechanisms involved in pathogenesis will allow the development of new treatment strategies. Cathelisidines constitute a protein class that is involved in the natural immune response of mammals. They are produced in the cell as pre-pro-protein. LL-37 is the single human katselidine derivative AMP. LL-37 is mainly synthesized in secondary granules of neutrophils. LL-37 is also synthesized in macrophages, mast cells, B and T lymphocytes, monocytes and keratinocytes, dendritic cells, respiratory, intestinal and urinary tract epithelial cells. Its main effects are antiviral, antibacterial, antifungal, antiparasitic, anticancer activity in breast, ovary, lung and stomach cancer, apoptosis, wound healing, cytotoxicity, chemotaxis. The interaction of LL-37 with intracellular proteins provides both antimicrobial activity and immune modulator effects. The efficacy of LL-37 is dose-related. The immunomodulatory effects of LL-37 are lower than the antimicrobial effects. LL-37 contains both proinflammatory and anti-inflammatory properties. The LL-37 modulates the immunomodulator effects through the Toll Like Receptor (TLR) pathway, regulating the type 1 interferon response, modulating the amount of cytokines affecting mononuclear cell maturation, and regulating apoptosis. There is a disturbance of TLR signaling in the pathogenesis of autoimmune diseases. There are several studies on immunological factors in pathogenesis in BD. But it is not known whether LL-37, the only human kathelicidine from the family of antimicrobial peptides associated with the inflammatory process, plays a role in the pathogenesis of BD. The aim of this study was to investigate the serum levels of LL-37, an inflammatory vasculitis in BD, responsible for the release of many proinflammatory cytokines, and their relationship with disease activity. This study was conducted between September and December 2018 in Dicle University Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Department of Skin and Venereal Diseases. The aim of this study was to determine serum LL-37 levels. Peripheral blood samples were taken from 45 BH and 37 healthy controls and serum cathelicidin (LL-37) levels were measured by ELISA method. There were no significant differences between the two groups in terms of the number of women (p = 0.0503), age (p = 0.357) and BMI (p = 0.133) in both groups. Serum LL-37 (p = 0,195) values did not differ significantly between the patient and the control group. Keywords, BD, LL-37, Disease activitiy