The inflammasomes, immune guardians at defence barriers

• Published in: Immunology Vol. 155; no. 3; pp. 320 - 330
• Main Authors: Palazon‐Riquelme, Pablo, Lopez‐Castejon, Gloria
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-11-2018; Wiley; John Wiley and Sons Inc
• Subjects: Activation; Animals; Bacteriology; Barriers; Cytokines; epithelial cell; Epithelial cells; Epithelial Cells - immunology; Epithelium; Hazards; Homeostasis; Humans; Immunology; inflammasome; Inflammasomes; Inflammasomes - immunology; Inflammation; Inflammatory response; Interleukin-18 - immunology; Interleukin-1beta - immunology; Interleukins; Life Sciences; Macromolecules; Microbiology and Parasitology; Molecular modelling; Review; Signal Transduction - immunology; Virology; epithelial cell; inflammation; inflammasome
• ISSN: 0019-2805; 1365-2567
• DOI: 10.1111/imm.12989

Summary
As a result of its strategic location, the epithelium is constantly exposed to a wide variety of pathogen and danger signals. Traditionally, the epithelium has been perceived as a defensive but passive barrier; however, it has now become evident that the epithelium senses and actively responds to these signals in order to maintain barrier homeostasis and contributes to the inflammatory response. One way it does this is by producing pro‐inflammatory cytokines including interleukin‐1β (IL‐1β) and IL‐18. These two cytokines are synthesized as inactive precursors, the maturation of which is mediated by pro‐inflammatory caspases after the activation and assembly of macromolecular complexes called inflammasomes. Epithelial cells express a large panel of inflammasome components, and although the molecular mechanisms underlying the activation of these complexes in haematopoietic cells are well understood, how epithelial cells react to danger signals to activate the inflammasome remains unclear. We review and discuss how different inflammasomes contribute to barrier homeostasis and inflammation at several barrier sites, their mechanisms and how their aberrant regulation contributes to disease at the different epithelia.
As a result of its strategic location, the epithelium is constantly exposed to a wide variety of pathogen and danger signals. It responds by producing pro‐inflammatory cytokines including the inflammasome‐dependent cytokines interleukin‐1β (IL‐1β) and IL‐18. We review and discuss how different inflammasomes contribute to barrier homeostasis and inflammation at several barrier sites.