Immunology of Behcet disease: review article

Behçet's disease (BD), also known as the Silk Road disease, is a multisystemic and rare inflammatory disorder primarily prevalent in populations along the Mediterranean Sea. Today, BD is defined as a crossroad between autoimmune and auto-inflammatory syndromes. Variety of syndromes including mucocutaneous manifestations such as oral and genital ulcers, papulopustular lesions and erythema nodosum as well as ocular, vascular, gastrointestinal and nervous system occur. The disease etiology has not yet been elaborated, though researchers have reported several reasons that can increase the likelihood of the disease occurrence including a genetic factor, human leukocyte antigen HLA-B51 (B51) antigen, infectious conditions such as herpes simplex virus (HSV), those involved in inflammatory and autoimmune conditions such as imbalance of various cytokines and immune cells levels as well as existence of various gene variants. Among the various immuno dysfunctions that are found in BD, patients have increased neutrophil motility and superoxide production, as well as elevated production of tumor necrosis factor (TNF)-α and decreased production of interleukin-10 (IL-10). Since vasculitis and tissue damage is usually seen with Behcet disease, unusual concentrations of chemokine and adhesion molecules can also help us understand the causes of disease. Among the functional deficiencies of the immune system, increased concentrations of neutrophils and monocytes are of importance leading to an increase in reactive oxygen species (ROS). Behcet's disease has common characteristics with some immune-mediated diseases such as systemic lupus erythematosus (SLE), psoriasis, ankylosing spondylitis, and inflammatory bowel disease (IBD), which suggests that they may share similar etiologies and genes. Genetic and epigenetic modulations have also been proposed as involved in the pathogenesis of BD. Modifications in DNA methylation have been found in BD patient monocytes and lymphocytes, leading to the adverse function of these cells. The positive replies to classical immunosuppressive agents like cyclosporine and azathioprine and participation of autoantigens at the beginning of the illness are the chief BD features that reflect the autoimmune nature of the disorder. This review article attempts to introduce the BD disease and its contributing factors with emphasis on the role of different cells and cytokines based on updated studies.