scholarly journals Loss of Smad5 leads to the disassembly of the apical junctional complex and increased susceptibility to experimental colitis

2011 ◽  
Vol 300 (4) ◽  
pp. G586-G597 ◽  
Author(s):  
Joannie M. Allaire ◽  
Mathieu Darsigny ◽  
Sébastien S. Marcoux ◽  
Sébastien A. B. Roy ◽  
Jean-Francois Schmouth ◽  
...  
Keyword(s):  
Wound Healing ◽  
Experimental Colitis ◽  
Recovery Phase ◽  
Bmp Signaling ◽  
Junctional Complex ◽  
Gene Transcript ◽  
Intestinal Epithelial ◽  
Impaired Wound Healing ◽  
Dss Colitis ◽  
Apical Junctional Complex

The regulation of intestinal epithelial cell adhesion and migratory properties is often compromised in inflammatory bowel disease (IBD). Despite an increasing interest in bone morphogenetic protein (Bmp) signaling in gut pathologies, little is known of the specific roles played by individual Smads in intestinal epithelial functions. In the present study, we generated a mouse model with deletion of Smad5 transcriptional effector of the Bmp signaling pathway exclusively in the intestinal epithelium. Proliferation, migration, and apical junctional complex (AJC) protein expression were analyzed by immunofluorescence and Western blot. Human intestinal biopsies from control and IBD patients were analyzed for SMAD5 gene transcript expression by quantitative PCR (qPCR). Smad5ΔIEC and control mice were subjected to dextran sulfate sodium (DSS)-induced experimental colitis, and their clinical and histological symptoms were assessed. Loss of Smad5 led to intestinal epithelial hypermigration and deregulation of the expression of claudin-1 and claudin-2. E-cadherin was found to be equally expressed but displaced from the AJC to the cytoplasm in Smad5ΔIEC mice. Analysis of SMAD5 gene expression in human IBD patient samples revealed a significant downregulation of the gene transcript in Crohn's disease and ulcerative colitis samples. Smad5ΔIEC mice exposed to experimental DSS colitis were significantly more susceptible to the disease and had impaired wound healing during the recovery phase. Our results support that Smad5 is partly responsible for mediating Bmp signals in intestinal epithelial cells. In addition, deficiency in epithelial Smad5 leads to the deregulation of cell migration by disassembling the AJC with increasing susceptibility to experimental colitis and impairment in wound healing.

scholarly journals P015 Tricellulin overexpression protects against elevated macromolecule uptake in DSS colitis mice

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S137-S137
Author(s):  
F WEIß ◽  
I F M Lee ◽  
A Fromm ◽  
J C E Hu ◽  
T Breiderhoff ◽  
...  
Keyword(s):  
Weight Loss ◽  
Activity Index ◽  
Disease Activity Index ◽  
Experimental Colitis ◽  
Sodium Sulphate ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Central Tube ◽  
Dss Colitis ◽  
Inflammatory Processes

Abstract Background In Inflammatory bowel disease, intestinal homeostasis cannot be sustained due to an overreaction of the immune system and a disturbed epithelial barrier due to an impaired tight junction (TJ). At tricellular TJs (tTJs), which are formed where three cells meet, the TJ network is basolaterally expanded and forms a central tube which would be potentially large enough to allow for a paracellular passage of macromolecules. Under normal conditions, the tTJ protein tricellulin (Tric) seals the central tube against luminal uptake. However, in ulcerative colitis (UC), Tric is downregulated, resulting in increased uptake of macromolecules including antigens which may further support the inflammatory processes. Thus, we aimed to identify whether or not overexpression of Tric has a protective effect against inflammation. Methods We generated intestinal epithelial cell-specific overexpression of Tric in mice (B6.C-Tg(Vil-cre) Rosa26tgGFP-Tric). In Tric-overexpressing (Tric-OE) and in wild-type (wt) mice experimental colitis was induced by 3% dextran sodium sulphate (DSS) for 6 days. The effect was assessed by determining the disease activity index (DAI: weight loss, stool consistency, and stool bleeding) and the colon dimensions. Using chamber experiments were performed to determine permeabilities for ions and macromolecules of different sizes (4 and 10 kDa). Results No difference in weight loss was observed between wt and Tric-OE mice upon DSS treatment. However, Tric-OE mice suffered less from diarrhoea and had less bloody stools compared with wt mice resulting in a lower DAI. In addition, DSS caused a reduced colon length which was less prominent in Tric-OE mice than in wt mice. Functional analysis revealed higher permeabilities for Na+ and Cl− after DSS treatment with no significant differences between Tric-OE and wt mice. In contrast, permeabilities for macromolecules of both sizes were unchanged after DSS treatment in Tric-OE mice but elevated in wt-mice. Conclusion Tric-overexpression prevents the epithelial barrier from elevated paracellular uptake of macromolecules during DSS colitis without affecting ion permeability. This protects against DSS colitis as indicated by less affected clinical and structural outcome parameters, most likely via a reduction in a load of immunologically active macromolecules in the subepithelium.

VALIDATION OF HPTM-001, A HUMANIZED CANDIDATE THERAPEUTIC ANTIBODY FOR PROMOTING MUCOSAL WOUND HEALING IN IBD

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S37-S37
Author(s):  
Tony Liang ◽  
Leonard Presta ◽  
Jennifer Brazil ◽  
Charles Parkos ◽  
Jennifer Cheng
Keyword(s):  
Wound Healing ◽  
Potential Candidate ◽  
Intestinal Epithelial ◽  
Murine Colitis ◽  
Dss Colitis ◽  
Human Intestinal Epithelial Cells ◽  
Clinical Consequences ◽  
Human Igg1 ◽  
Mucosal Wound

Abstract A hallmark of the clinical course of patients with Inflammatory Bowel Disease (IBD) is poorly healing erosions and ulcers in the intestinal mucosa. Despite the adverse clinical consequences of non-healing mucosal wounds in IBD, current front-line therapies that selectively target mucosal wound healing are not available. Recent studies revealed an association between colonic inflammation and aberrant glycosylation of epithelial CD44v6. Under conditions of inflammation, epithelial CD44v6 was shown to be decorated with the terminal glycan sialyl Lewis A. Importantly, targeting sialylated Lewis glycans on CD44v6 with a murine antibody GM35 was shown to promote mucosal wound healing in cell lines and in biopsy based wounding assays as well as dextran sodium sulfate (DSS) induced murine colitis models. We sequenced CDRs from GM35 and produced a humanized antibody. Eight candidate human IgG1 clones were produced and screened. hPTM-001.4772 was selected from the eight candidates based on glycan affinity and selectivity compared to GM35. In vitro wound healing studies revealed that PTM-001.4772 was as effective as GM35 in promoting repair of scratch wounds with human intestinal epithelial cells. Furthermore, intraperitoneal injection of mice with hPTM-001.4772 during induction of DSS colitis resulted in reduced weight loss compared to control IgG. These results suggest that hPTM-001.4772 is well-positioned as a unique potential candidate therapeutic for IBD that can be used to selectively promote healing of mucosal wounds and ulcers.

scholarly journals SIRPα sequesters SHP-2 to promote IL-4/13 signaling and alternative activation of macrophages

2021 ◽  
Author(s):  
Lei Shi ◽  
Koby Kidder ◽  
Zhen Bian ◽  
Samantha Kuon Ting Chiang ◽  
Corbett Ouellette ◽  
...  
Keyword(s):  
Wound Healing ◽  
Ex Vivo ◽  
Experimental Colitis ◽  
Alternative Activation ◽  
Activated Macrophages ◽  
Negative Regulators ◽  
Impaired Wound Healing ◽  
Alternatively Activated Macrophages ◽  
Arginase 1 ◽  
Alternatively Activated

The Th2 cytokines IL-4 and IL-13 through activation of their shared receptor IL-4Rα direct macrophage alternative activation to promote immunosuppression and wound healing. However, the mechanisms that control macrophage responses to IL-4/13 are not fully understood. Apart from driving JAK-STAT and PI3K-Akt pathways to polarize macrophages toward the alternative phenotype, the activated IL-4/13 receptors recruit negative regulators SHP-1 and SHP-2, which dephosphorylate IL-4Rα and decrease its signaling. Here we report that SIRPα spatially restricts SHP-2 and, by such, promotes IL-4/13 signaling and macrophage alternative activation. SIRPα executes this regulation via its cytoplasmic ITIMs/ITSMs that undergo phosphorylation by IL-4/13-induced, Src kinase-activated Brutons tyrosine kinase (Btk), resulting in recruitment of SHP-2 and preclusion of SHP-2 from binding to and inhibiting IL-4/13 receptors. Despite that this regulation occurs independent of CD47, extracellular CD47 ligation of SIRPα facilitates its cytoplasmic phosphorylation and SHP-2 sequestration, leading to stronger IL-4/13 signaling and enhanced macrophage expression of IL-10, TGFβ, CD206, arginase-1, etc. Conversely, deficiency of SIRPα allows SHP-2 to freely bind to γC or IL-13Rα1 and through which dephosphorylate IL-4Rα, dampening its signaling. Consistent with these findings, impaired wound healing in Sirpα-/- mice under experimental colitis correlated with a deficit of immunosuppressive macrophages in the colon, a condition that was corrected by transfusion of ex vivo-produced SIRPαhigh alternatively activated macrophages.

scholarly journals Death-associated protein kinase 3 (DAPK3) contributes to intestinal epithelial wound healing and the resolution of experimental colitis in mice

2021 ◽  
Author(s):  
Huey-Miin Chen ◽  
David A. Carlson ◽  
Timothy A.J. Haystead ◽  
Justin A. MacDonald
Keyword(s):  
Wound Healing ◽  
Protein Kinase ◽  
Experimental Colitis ◽  
Cell Types ◽  
Sodium Sulphate ◽  
Intestinal Epithelial ◽  
Epithelial Regeneration ◽  
Human Intestinal Epithelial Cells ◽  
Death Associated Protein Kinase ◽  
Key Factor

ABSTRACTVarious signaling molecules affecting epithelial restitution and wound healing are dysregulated in ulcerative colitis. Recent evidence demonstrates the necessity of Hippo-YAP/TAZ signaling, interceded by cytoskeletal remodeling, for intestinal regeneration. Death-associated protein kinase 3 (DAPK3) is a regulator of actin cytoskeleton reorganization that controls proliferation and apoptosis. Pharmacological inhibition of DAPK3 in Caco-2 human intestinal epithelial cells (IECs) with the HS38 compound augmented cell proliferation and enhanced wound closure. This phenotype corresponded with the increased colocalization of Yes-associated protein (YAP) with F-actin, which is indicative of YAP activation. The administration of HS38 impeded the resolution of intestinal injury and attenuated epithelial-specific proliferation after acute colitis induced by dextran-sodium-sulphate (DSS) in mice. During recovery from DSS-induced colitis, IEC proliferation was repressed, and mice exhibited increased disease severity when HS38 was applied to inhibit DAPK3. Moreover, HS38 treatment increased YAP nuclear localization in IECs, an indicator of signal activation. In summary, this study established DAPK3 as a key factor in intestinal epithelial regeneration and colitis progression by way of YAP signaling. Nevertheless, the role that DAPK3 play in different cell types will need further investigation to decipher the full consequence of DAPK3 inhibition on epithelial homeostasis.

scholarly journals Endocytosis and Recycling of Tight Junction Proteins in Inflammation

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Markus Utech ◽  
Rudolf Mennigen ◽  
Matthias Bruewer
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Junctional Complex ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Critical Function ◽  
Recycling Endosomes ◽  
Inflammatory Conditions ◽  
Apical Junctional Complex ◽  
Junction Proteins

A critical function of the epithelial lining is to form a barrier that separates luminal contents from the underlying interstitium. This barrier function is primarily regulated by the apical junctional complex (AJC) consisting of tight junctions (TJs) and adherens junctions (AJs) and is compromised under inflammatory conditions. In intestinal epithelial cells, proinflammatory cytokines, for example, interferon-gamma (IFN-γ), induce internalization of TJ proteins by endocytosis. Endocytosed TJ proteins are passed into early and recycling endosomes, suggesting the involvement of recycling of internalized TJ proteins. This review summarizes mechanisms by which TJ proteins under inflammatory conditions are internalized in intestinal epithelial cells and point out comparable mechanism in nonintestinal epithelial cells.

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