Human beings are constantly exposed to pathogens. The innate immune system is 
the first line of defense against microbes. It has evolved to recognize 
conserved microbial motifs (PAMP or pathogen-associated molecular patterns) 
thanks to a limited array of receptors termed pattern recognition receptors 
(PRR). Upon activation, most PRR trigger a transcriptional response leading to 
neosynthesis of hundreds of genes. In contrast, engagement of various PRR in the 
recently identified inflammasome complexes lead to activation of a cysteine 
protease, caspase-1. This inflammatory caspase has a dual activity: it triggers 
the release of very potent proinflammatory cytokines IL-1β and IL-18 and, an 
hyperinflammatory cell death termed pyroptosis. In this review, we describe the 
inflammasome receptors and their ligands, the molecular mechanisms leading to 
the assembly of this innate immune platform and the role of the inflammasome 
during viral and bacterial infections.