Caspase-11 promotes allergic airway inflammation

Activated caspase-1 and caspase-11 induce inflammatory cell death in a process termed pyroptosis. Here we show that Prostaglandin E 2 (PGE 2 ) inhibits caspase-11-dependent pyroptosis in murine and human macrophages. PGE 2 suppreses caspase-11 expression in murine and human macrophages and in the airways of mice with allergic inflammation. Remarkably, caspase-11-deficient mice are strongly resistant to developing experimental allergic airway inflammation, where PGE 2 is known to be protective. Expression of caspase-11 is elevated in the lung of wild type mice with allergic airway inflammation. Blocking PGE 2 production with indomethacin enhances, whereas the prostaglandin E 1 analog misoprostol inhibits lung caspase-11 expression. Finally, alveolar macrophages from asthma patients exhibit increased expression of caspase-4, a human homologue of caspase-11. Our findings identify PGE 2 as a negative regulator of caspase-11-driven pyroptosis and implicate caspase-4/11 as a critical contributor to allergic airway inflammation, with implications for pathophysiology of asthma. Caspase 11 activation involves transcriptional upregulation and proteolytic cleavage. Here the authors show that prostaglandin E 2 prevents caspase-11-mediated pyroptosis, blocking caspase-11 mRNA and protein upregulation in macrophages and in vivo, and that mice lacking caspase-11 are strongly protected from allergic airway inflammation.