Interleukin-33 （IL-33）, a newly recognized IL-1 family member, is expressed by various tissues and cells. Since it can combine with chromosomes, IL-33 is regarded as an intracellular transcription repressor. Upon proinflammatory stimulation, it is released as an extracellular cytokine to function as an alarmin to dangerous signals. The IL-33 receptor is a heterodimer complex composed of ST2 and the IL-1 receptor accessory protein, the latter being conserved in other IL-1 family members. The IL-33/ST2 signaling pathway plays critical roles in inflammatory and immune diseases, as well as in central nervous system （CNS） diseases. Recently, there has been an increasing focus on IL-33, particularly on its production and functions in the CNS. The present review mainly focuses on progress in research on IL-33, especially its roles in the CNS.
The NLRP3 inflammasome,which consists of the NLRP3（nucleotide-binding oligomerization domain（Nod）–like receptor 3） scaffold,the ASC（apoptosis-associated speck-like protein containing a CARD） adaptor and procaspase-1,is assembled after the cytoplasmic LRRs（leucine-rich repeats） of NLRP3 sense pathogens or danger signals.The NLRP3 inflammasome controls the activation of the proteolytic enzyme caspase-1.Caspase-1 in turn regulates the maturation of the proinflammasome cytokines IL-1β and IL-18,which leads to an inflammatory response.The inflammasome plays an important role in the development of Alzheimer’s disease and bacterial meningitis,and the NLRP3 inflammasome may become a new target for the prevention and treatment of central nervous system diseases.
