The Goldilocks Conundrum: NLR Inflammasome Modulation of Gastrointestinal Inflammation during Inflammatory Bowel Disease.
Recent advances have revealed significant insight into inflammatory bowel disease (IBD) pathobiology. Ulcerative colitis and Crohn's disease, the chronic relapsing clinical manifestations of IBD, are complex disorders with genetic and environmental influences. These diseases are associated with the dysregulation of immune tolerance, excessive inflammation, and damage to the epithelial cell barrier. Increasing evidence indicates that pattern recognition receptors, including Toll-like receptors (TLRs) and nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs), function to maintain immune system homeostasis, modulate the gastrointestinal microbiome, and promote proper intestinal epithelial cell regeneration and repair. New insights have revealed that NLR family members are essential components in maintaining this immune system homeostasis. To date, the vast majority of studies associated with NLRs have focused on family members that form a multiprotein signaling platform called the inflammasome. These signaling complexes are responsible for the cleavage and activation of the potent pleotropic cytokines IL-1β and IL-18, and they facilitate a unique form of cell death defined as pyroptosis. In this review, we summarize the current paradigms associated with NLR inflammasome maintenance of immune system homeostasis in the gastrointestinal system. New concepts related to canonical and noncanonical inflammasome signaling, as well as the implications of classical and alternative inflammasomes in IBD pathogenesis, are also reviewed.
Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061.
Veronica M
VM
Ringel-Scaia
Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061.
Dylan K
DK
McDaniel
Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA 24061; Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061.
Irving C
IC
Allen
D000818:Animals; D000069196:Gastrointestinal Microbiome; D006801:Humans; D007107:Immune System / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D058847:Inflammasomes / Q000378:metabolism*; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000209:etiology* / Q000378:metabolism*; D000090263:Leucine-Rich Repeat Proteins; D000070576:NLR Proteins / Q000378:metabolism; D009369:Neoplasms / Q000209:etiology / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000378:metabolism
D058847:Inflammasomes; D000090263:Leucine-Rich Repeat Proteins; D000070576:NLR Proteins; D011506:Proteins; D051193:Toll-Like Receptors