Inflammasomes and inflammatory caspases in skin inflammation.

The inflammatory caspases comprise a subclass of caspases associated with immune responses. Caspase-1 was the first identified member of this class, which also includes caspase-4, -5, -11 and -12. Caspase-1 was identified as the IL-1beta-converting enzyme and, more recently, it has also been shown to activate IL-18 and IL-33. Activation of the inflammatory caspases occurs upon assembly of multiprotein complexes, termed inflammasomes. The inflammasomes and inflammatory caspases are part of the innate immune system, which constitutes the first line of defense that detects pathogens, such as nonself antigens, bacterial and viral components, and other danger signals, and orchestrates the immune response. Inflammasomes and inflammatory caspases have also been suggested to bridge the innate immune responses to the adaptive immune system. More recently, the expression and role of inflammasomes and inflammatory caspases have been studied in both human and rodent skin, and findings have indicated a possible key role of these regulators of the immune system in the pathogenesis of inflammatory skin diseases. This article will review some of the most recent findings, identifying inflammasomes and inflammatory caspases as potential inducers and regulators of skin inflammation in contact hypersensitivity and psoriasis.