Behçet's disease (BD) is a multi-system auto inflammatory disorder with vasculitic features. The exact etiological of BD is still obscure, although environmental and genetics factors have been found to be involved in disease pathogenesis.FSTL-1 can act as diagnostic and prognostic biomarkers for Some inflammatory autoimmune diseases including BD.

Behçet's disease (BD) is a multi-system auto inflammatory disorder with vasculitic features Clinical manifestation of BD includes recurrent oral and genital ulcerations, uveitis, skin lesions, vascular, neurological, and gastrointestinal manifestations.The exact etiological of BD is still obscure, although environmental and genetics factors have been found to be involved in disease pathogenesis. Most of BD manifestations have features of systemic perivasculitis. Cell-mediated immunity has a significant role in BD pathogenesis . Activation of Type 1 helper T (Th1) cell will increase levels of circulating T-lymphocytes, with subsequent increase in the levels of proinflammatory cytokines accounting for most of BD symptoms. These proinflammatory cytokines may be used as an indicator of disease severity. Also Increased macrophage activation, neutrophil chemotaxis, and phagocytosis have been described in BD lesion. Indeed, the need for studying biomarkers that may drive inflammatory pathways involved in BD pathogenesis is crucial. Follistatin-like proteins (FLP) belong to the family of acidic cysteine-rich secreted glycoproteins (SPARC) that are highly homologous to the activin-binding protein, follistatin (FST)(7). this group of proteins include five types: FSTL1, FSTL2, FSTL3, FSTL4 and FSTL5. Follistatin-like protein 1 (FSTL-1) is a soluble gly¬coprotein expressed by mesenchymal cells. It has been involved in various signaling pathways and biological processes. FSTL1 has dual effect in inflammatory processes and has been evaluated in some laboratory models and can serve as pro-inflammatory and anti-inflammatory markers. During the acute inflammation FSL1 may act as an anti-inflammatory factor, while they exert a pro-inflammatory effect in chronic inflammation. This dual effect has been explained by activation of several signaling pathways. Although, additional exogenous and endogenous factors, may be involved in such regulation. Increased serum levels FSTL1 levels were found in some of autoimmune systemic diseases including rheumatoid arthritis, Sjogren's syndrome and osteoarthritis. Moreover, the In¬creased serum levels of FSTL-1 where found to be positively correlated with disease activity in some autoim¬mune diseases, including, rheumatoid arthritis (RA), juvenile idiopathic arthritis and systemic lupus ery¬thematosus (SLE). Based on the above mention findings, FSTL-1 can act as diagnostic and prognostic biomarkers for Some inflammatory autoimmune diseases including BD.