Increased expression of the NLRP3 inflammasome components in patients with Behcet's disease

Background: Behcet's disease (BD) is a systemic inflammatory disease with manifestations including recurrent oral and genital ulcerations, and vasculitis involving the skin, mucosa, joints, eyes, veins, arteries, nervous and gastrointestinal systems. BD is seen as a disease at the crossroad between autoimmune and autoinflammatory syndromes, possibly triggered by an aberrant response to infectious stimuli. The relevance of Gram negative bacteria-mediated oral inflammation with the increased expression of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), leading to systemic inflammation, prompted us to investigate the expression of NLRP3 inflammasome components and its link with IL-1 beta hypersecretion. Findings: When peripheral blood mononuclear cells (PBMCs) from 15 active, 15 stable BD patients and 15 healthy volunteers were stimulated, the basal and LPS-induced expressions of NLRP3 inflammasome components were significantly increased at both mRNA and protein levels in BD patients compared to healthy controls. Also, increased expression of NLRP3 and ASC was observed in 25 BD skin lesions compared to 25 erythema nodosum patients. Compatible with this, secretion of IL-1 beta by PBMCs stimulated with LPS alone or LPS plus ATP was increased in BD compared to healthy controls, which was suppressed by caspase-1 inhibitor. Conclusion: Our findings suggest the possible link between increased IL-1 beta secretion and increased expression of NLRP3 inflammasome components in BD patients with skin manifestations.