title: Toll-like receptor 4-mediated endoplasmic reticulum stress in intestinal crypts induces necrotizing enterocolitis.
abstract: The cellular cues that regulate the apoptosis of intestinal stem cells (ISCs) remain incompletely understood, yet may play a role in diseases characterized by ISC loss including necrotizing enterocolitis (NEC). Toll-like receptor-4 (TLR4) was recently found to be expressed on ISCs, where its activation leads to ISC apoptosis through mechanisms that remain incompletely explained. We now hypothesize that TLR4 induces endoplasmic reticulum (ER) stress within ISCs, leading to their apoptosis in NEC pathogenesis, and that high ER stress within the premature intestine predisposes to NEC development. Using transgenic mice and cultured enteroids, we now demonstrate that TLR4 induces ER stress within Lgr5 (leucine-rich repeat-containing G-protein-coupled receptor 5)-positive ISCs, resulting in crypt apoptosis. TLR4 signaling within crypts was required, because crypt ER stress and apoptosis occurred in TLR4(ΔIEC-OVER) mice expressing TLR4 only within intestinal crypts and epithelium, but not TLR4(ΔIEC) mice lacking intestinal TLR4. TLR4-mediated ER stress and apoptosis of ISCs required PERK (protein kinase-related PKR-like ER kinase), CHOP (C/EBP homologous protein), and MyD88 (myeloid differentiation primary response gene 88), but not ATF6 (activating transcription factor 6) or XBP1 (X-box-binding protein 1). Human and mouse NEC showed high crypt ER stress and apoptosis, whereas genetic inhibition of PERK or CHOP attenuated ER stress, crypt apoptosis, and NEC severity. Strikingly, using intragastric delivery into fetal mouse intestine, prevention of ER stress reduced TLR4-mediated ISC apoptosis and mucosal disruption. These findings identify a novel link between TLR4-induced ER stress and ISC apoptosis in NEC pathogenesis and suggest that increased ER stress within the premature bowel predisposes to NEC development.
authors: From the Divisions of Pediatric Surgery.
authors: Amin
authors: A
authors: Afrazi
authors: Maria F
authors: MF
authors: Branca
authors: Chhinder P
authors: CP
authors: Sodhi
authors: Misty
authors: M
authors: Good
authors: Yukihiro
authors: Y
authors: Yamaguchi
authors: Charlotte E
authors: CE
authors: Egan
authors: Peng
authors: P
authors: Lu
authors: Hongpeng
authors: H
authors: Jia
authors: Shahab
authors: S
authors: Shaffiey
authors: Joyce
authors: J
authors: Lin
authors: Congrong
authors: C
authors: Ma
authors: Garrett
authors: G
authors: Vincent
authors: Thomas
authors: T
authors: Prindle
authors: Samantha
authors: S
authors: Weyandt
authors: Matthew D
authors: MD
authors: Neal
authors: John A
authors: JA
authors: Ozolek
authors: John
authors: J
authors: Wiersch
authors: Markus
authors: M
authors: Tschurtschenthaler
authors: Chiyo
authors: C
authors: Shiota
authors: George K
authors: GK
authors: Gittes
authors: Timothy R
authors: TR
authors: Billiar
authors: Kevin
authors: K
authors: Mollen
authors: Arthur
authors: A
authors: Kaser
authors: Richard
authors: R
authors: Blumberg
authors: David J
authors: DJ
authors: Hackam
mesh_terms: D051702:Activating Transcription Factor 6 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D059865:Endoplasmic Reticulum Stress; D020345:Enterocolitis, Necrotizing / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D057809:HEK293 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D013234:Stem Cells / Q000378:metabolism* / Q000473:pathology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism
chemical_list: D051702:Activating Transcription Factor 6; D051197:Toll-Like Receptor 4; D051742:Transcription Factor CHOP; D019892:eIF-2 Kinase; C497111:ATF6 protein, human; C497112:Atf6 protein, mouse; C497249:DDIT3 protein, human; C497250:Ddit3 protein, mouse; C495345:TLR4 protein, human; C493487:Tlr4 protein, mouse; C460640:EIF2AK3 protein, human
keywords: Inflammation; Innate Immunity; Necrotizing Enterocolitis; Sepsis; Toll-like Receptors (TLR)