Repair In Colitis Research Articles

CD300b regulates intestinal inflammation and promotes repair in colitis.

Chronic inflammation is a hallmark charataristic of various inflammatory diseases including inflammatory bowel disease. Subsequently, current therapeutic approaches target immune-mediated pathways as means for therapeutic intervention and promotion of mucosal healing and repair. Emerging data demonstrate important roles for CD300 receptor family members in settings of innate immunity as well as in allergic and autoimmune diseases. One of the main pathways mediating the activities of CD300 family members is via promotion of resolution through interactions with ligands expressed by viruses, bacteria, or dead cells (e.g., phospholipids such as PtdSer and/or ceramide). We have recently shown that the expression of CD300a, CD300b and CD300f were elevated in patients with IBD and that CD300f (but not CD300a) regulates colonic inflammation in response to dextran sodium sulphate (DSS)-induced colitis. Whether CD300b has a role in colitis or mucosal healing is largely unknown. Herein, we demonstrate a central and distinct role for CD300b in colonic inflammation and subsequent repair. We show that Cd300b-/- mice display defects in mucosal healing upon cessation of DSS treatment. Cd300b-/- mice display increased weight loss and disease activity index, which is accompanied by increased colonic histopathology, increased infiltration of inflammatory cells and expression of multiple pro-inflammatory upon cessation of DSS cytokines. Furthermore, we demonstrate that soluble CD300b (sCD300b) is increased in the colons of DSS-treated mice and establish that CD300b can bind mouse and human epithelial cells. Finally, we show that CD300b decreases epithelial EpCAM expression, promotes epithelial cell motility and wound healing. These data highlight a key role for CD300b in colonic inflammation and repair processes and suggest that CD300b may be a future therapeutic target in inflammatory GI diseases.

Estrogen receptor β activation inhibits colitis by promoting NLRP6-mediated autophagy.

Estrogen receptor β (ERβ) and NOD-like receptor family pyrin domain containing 6 (NLRP6) are highly expressed in intestinal tissues. Loss of ERβ and NLRP6 exacerbate colitis in mouse models; however, the underlying mechanisms are incompletely understood. Here, we report that ERβ directly activates the NLRP6 gene expression via binding to estrogen responsive element of Nlrp6 gene promoter. ERβ also physically interacts with the NLRP6 nucleotide-binding domain and promotes NLRP6 inflammasome assembly. The ERβ-NLRP6 axis then interacts with multiple autophagy-related proteins, including ULK1, BECN1, ATG16L1, LC3B, and p62, and affects the autophagosome biogenesis and autophagic flux. Finally, NLRP6-mediated autophagy suppresses the inflammatory response by promoting the K48-linked polyubiquitination of ASC, Casp-1 p20, IL-1β, TNF-α, and prohibitin-2. Thus, ERβ-NLRP6 direct an anti-inflammatory response by promoting autophagy. Our work uncovers an ERβ-NLRP6-autophagy pathway as a regulatory mechanism that maintains intestinal epithelial cell homeostasis and facilitates tissue repair in colitis.

Oral administration of turmeric-derived exosome-like nanovesicles with anti-inflammatory and pro-resolving bioactions for murine colitis therapy

BackgroundUlcerative colitis (UC) is an inflammatory bowel disease (IBD) characterized by diffuse inflammation of the colonic mucosa and a relapsing and remitting course. The current therapeutics are only modestly effective and carry risks for unacceptable adverse events, and thus more effective approaches to treat UC is clinically needed.ResultsFor this purpose, turmeric-derived nanoparticles with a specific population (TDNPs 2) were characterized, and their targeting ability and therapeutic effects against colitis were investigated systematically. The hydrodynamic size of TDNPs 2 was around 178 nm, and the zeta potential was negative (− 21.7 mV). Mass spectrometry identified TDNPs 2 containing high levels of lipids and proteins. Notably, curcumin, the bioactive constituent of turmeric, was evidenced in TDNPs 2. In lipopolysaccharide (LPS)-induced acute inflammation, TDNPs 2 showed excellent anti-inflammatory and antioxidant properties. In mice colitis models, we demonstrated that orally administrated of TDNPs 2 could ameliorate mice colitis and accelerate colitis resolution via regulating the expression of the pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, and antioxidant gene, HO-1. Results obtained from transgenic mice with NF-κB-RE-Luc indicated that TDNPs 2-mediated inactivation of the NF-κB pathway might partially contribute to the protective effect of these particles against colitis.ConclusionOur results suggest that TDNPs 2 from edible turmeric represent a novel, natural colon-targeting therapeutics that may prevent colitis and promote wound repair in colitis while outperforming artificial nanoparticles in terms of low toxicity and ease of large-scale production.

TNF hampers intestinal tissue repair in colitis by restricting IL-22 bioavailability

Successful treatment of chronic inflammatory diseases integrates both the cessation of inflammation and the induction of adequate tissue repair processes. Strikingly, targeting a single proinflammatory cytokine, tumor necrosis factor (TNF), induces both processes in a relevant cohort of inflammatory bowel disease (IBD) patients. However, the molecular mechanisms underlying intestinal repair following TNF blockade during IBD remain elusive. Using a novel humanized model of experimental colitis, we demonstrate that TNF interfered with the tissue repair program via induction of a soluble natural antagonist of IL-22 (IL-22Ra2; IL-22BP) in the colon and abrogated IL-22/STAT3-mediated mucosal repair during colitis. Furthermore, membrane-bound TNF expressed by T cells perpetuated colonic inflammation, while soluble TNF produced by epithelial cells (IECs) induced IL-22BP expression in colonic dendritic cells (DCs) and dampened IL-22-driven restitution of colonic epithelial functions. Finally, TNF induced IL-22BP expression in human monocyte-derived DCs and levels of IL22-BP correlated with TNF in sera of IBD patients. Thus, our data can explain how anti-TNF therapy induces mucosal healing by increasing IL-22 availability and implicates new therapeutic opportunities for IBD.

The Candidate IBD Risk Gene CCNY Is Dispensable for Intestinal Epithelial Homeostasis.

The CCNY gene, which encodes cyclin Y, has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Cyclin Y promotes Wnt/β-catenin signaling and autophagy, which are critical for intestinal epithelial cell (IEC) homeostasis, and may thereby contribute to wound repair in colitis. However, whether cyclin Y has an essential function in IECs is unknown. We, therefore, investigated the epithelial injury response and mucosal regeneration in mice with conditional knock-out of Ccny in the intestinal epithelium. We observed that Ccny-deficient mice did not exhibit any differences in cell proliferation and disease activity compared to wild-type littermates in the dextran sulfate sodium (DSS) colitis model. Complementary in vitro experiments showed that loss of CCNY in model IECs did not affect Wnt signaling, cell proliferation, or autophagy. Additionally, we observed that expression of the cyclin-Y-associated cyclin-dependent kinase (CDK) 14 is exceedingly low specifically in IEC. Collectively, these results suggest that cyclin Y does not contribute to intestinal epithelial homeostasis, possibly due to low levels of specific CDKs in these cells. Thus, it is unlikely that CCNY mutations are causatively involved in IBD pathogenesis.

Mo1931 Monocyte-Derived Macrophages Are Essential for the Resolution of Inflammation and Tissue Repair in Colitis

Mo1931 Monocyte-Derived Macrophages Are Essential for the Resolution of Inflammation and Tissue Repair in Colitis

P066. CCR2-monocytes are essential for the resolution of inflammation and tissue repair in colitis.

P066. CCR2-monocytes are essential for the resolution of inflammation and tissue repair in colitis.

784 Impaired Resolution of Inflammation and Tissue Regeneration in Corticotropin Releasing Hormone (CRH)- Deficient Mice Following DSS-Colitis

Inflammatory bowel disease (IBD) is a chronic, relapsing disease owing its development on complex interactions between genetic and environmental factors. It is currently accepted that innate immunity and indigenous pathogens play a critical role in the pathophysiology of IBD by compromising the function of the epithelial barrier. In previous studies we have demonstrated immunomodulatory actions of Corticotropin Releasing Hormone, or Factor, (CRH or CRF), a neuropeptide acting as the major mediator of the stress response, in intestinal inflammation in rodents. CRH and its receptors are expressed in a variety of tissues in humans and rodents including the intestine. Using an experimental model of innate immunity-dependent ulcerative colitis, the DSS model, we have recently shown that Crh deficiency is associated with increased susceptibility to disease development, indicating new roles for CRH in innate immune responses. To extend our understanding on the role of CRH in experimental IBD, we followed the course of DSS-colitis during the phase of repair of the tissue injury. To our surprise the disease was progressed in the Crh-/mice 5 days following cessation of DSS treatment resulting in their severely compromised survival, while all wild-type mice recovered. The progressive disease in the Crh-/mice was characterized by significant body weight loss, lack of regeneration of the epithelial barrier, and signs of increased fibrosis. Preliminary findings suggest that recovery of the vascularization and the innervation of the injured tissue follow an abnormal pattern. Thus, we identified prominent expression of beta III tubulin, a neuron specific cytoskeletal protein, and synaptophysin, a major synaptic vesicle protein, during the early phase of the disease unlike the late expression in the normal mice. The significance of these findings for the adverse course of the disease in the Crh-/mice, given recent reports on the significant correlation between gut innervation and inflammation, is under investigation. Our findings demonstrate the requirement of CRH for the intestinal epithelial repair in colitis and raise the hypothesis of the critical contribution of “appropriate” tissue stress response for the resolution of inflammation and return to tissue homeostasis in the gut.