Intestinal stenosis in Crohn's disease shows a generalized upregulation of genes involved in collagen metabolism and recognition that could serve as novel anti-fibrotic drug targets

Background and Aims: Crohn's disease (CD) can be complicated by intestinal fibrosis. Pharmacological therapies against intestinal fibrosis are not available. The aim of this study was to determine whether pathways involved in collagen metabolism are upregulated in intestinal fibrosis, and to discuss which drugs might be suitable to inhibit excessive extracellular matrix formation targeting these pathways. Methods: Human fibrotic and non-fibrotic terminal ileum was obtained from patients with CD undergoing ileocecal resection due to stenosis. Genes involved in collagen metabolism were analyzed using a microfluidic low-density TaqMan array. A literature search was performed to find potential anti-fibrotic drugs that target proteins/enzymes involved in collagen synthesis, its degradation and its recognition. Results: mRNA expression of collagen type I (COL1A1, 0.76 ± 0.28 versus 37.82 ± 49.85, p = 0.02) and III (COL3A1, 2.01 ± 2.61 versus 68.65 ± 84.07, p = 0.02) was increased in fibrotic CD compared with non-fibrotic CD. mRNA expression of proteins involved in both intra- and extracellular post-translational modification of collagens (prolyl- and lysyl hydroxylases, lysyl oxidases, chaperones), collagen-degrading enzymes (MMPs and cathepsin-K), and collagen receptors were upregulated in the fibrosis-affected part. A literature search on the upregulated genes revealed several potential anti-fibrotic drugs. Conclusion: Expression of genes involved in collagen metabolism in intestinal fibrosis affected terminal ileum of patients with CD reveals a plethora of drug targets. Inhibition of post-translational modification and altering collagen metabolism might attenuate fibrosis formation in the intestine in CD. Which compound has the highest potential depends on a combination anti-fibrotic efficacy and safety, especially since some of the enzymes play key roles in the physiology of collagen

Peribiliary glands are key in regeneration of the human biliary epithelium after severe bile duct injury

Peribiliary glands (PBG) are a source of stem/progenitor cells organized in a cellular network encircling large bile ducts. Severe cholangiopathy with loss of luminal biliary epithelium has been proposed to activate PBG, resulting in cell proliferation and differentiation to restore biliary epithelial integrity. However, formal evidence for this concept in human livers is lacking. We, therefore, developed a novel ex vivo model using precision-cut slices of extrahepatic human bile ducts obtained from discarded donor livers, providing an intact anatomical organization of cell structures, to study spatiotemporal differentiation and migration of PBG cells after severe biliary injury. Post-ischemic bile duct slices were incubated in oxygenated culture medium for up to a week. At baseline, severe tissue injury was evident with loss of luminal epithelial lining and mural stroma necrosis. In contrast, PBG remained relatively well preserved and different reactions of PBG were noted, including PBG dilatation, cell proliferation and maturation. Proliferation of PBG cells increased after 24 h of oxygenated incubation, reaching a peak after 72 h. Proliferation of PBG cells was paralleled by a reduction in PBG apoptosis and differentiation from a primitive and pluripotent (Nanog+/Sox9+) to a mature (CFTR+/secretin receptor+) and activated phenotype (increased expression of HIF-1α, Glut-1, and VEGF-A). Migration of proliferating PBG cells in our ex vivo model was unorganized, but resulted in generation of epithelial monolayers at stromal surfaces. CONCLUSION: Human PBG contain biliary progenitor cells and are able to respond to bile duct epithelial loss with proliferation, differentiation, and maturation to restore epithelial integrity. The ex vivo spatiotemporal behaviour of human PBG cells provides evidence for a pivotal role of PBG in biliary regeneration after severe injury. This article is protected by copyright. All rights reserved

Fasting induces a biphasic adaptive metabolic response in murine small intestine

BACKGROUND: The gut is a major energy consumer, but a comprehensive overview of the adaptive response to fasting is lacking. Gene-expression profiling, pathway analysis, and immunohistochemistry were therefore carried out on mouse small intestine after 0, 12, 24, and 72 hours of fasting. RESULTS: Intestinal weight declined to 50% of control, but this loss of tissue mass was distributed proportionally among the gut's structural components, so that the microarrays' tissue base remained unaffected. Unsupervised hierarchical clustering of the microarrays revealed that the successive time points separated into distinct branches. Pathway analysis depicted a pronounced, but transient early response that peaked at 12 hours, and a late response that became progressively more pronounced with continued fasting. Early changes in gene expression were compatible with a cellular deficiency in glutamine, and metabolic adaptations directed at glutamine conservation, inhibition of pyruvate oxidation, stimulation of glutamate catabolism via aspartate and phosphoenolpyruvate to lactate, and enhanced fatty-acid oxidation and ketone-body synthesis. In addition, the expression of key genes involved in cell cycling and apoptosis was suppressed. At 24 hours of fasting, many of the early adaptive changes abated. Major changes upon continued fasting implied the production of glucose rather than lactate from carbohydrate backbones, a downregulation of fatty-acid oxidation and a very strong downregulation of the electron-transport chain. Cell cycling and apoptosis remained suppressed. CONCLUSION: The changes in gene expression indicate that the small intestine rapidly looses mass during fasting to generate lactate or glucose and ketone bodies. Meanwhile, intestinal architecture is maintained by downregulation of cell turnove

The Citrullinated and MMP-degraded Vimentin Biomarker (VICM) Predicts Early Response to Anti-TNF alpha Treatment in Crohn's Disease

Background: In Crohn's disease (CD), 10% to 40% of patients do not respond to anti-tumor necrosis factor- (TNF) treatment. Currently, there are no biomarkers with adequate sensitivity to separate responders from nonresponders at an early stage. Aim: The aim of this study was to investigated whether early changes in the VICM (citrullinated and matrix metalloproteinase-degraded vimentin) biomarker were associated with response to anti-TNF treatment in patients with CD. Methods: Serum VICM levels were measured by ELISA in 2 independent cohorts of CD patients (n=42) treated with anti-TNF (infliximab or adalimumab). Response was determined by achieving clinical remission (Harvey Bradshaw Index<5). Results: Compared with baseline, VICM serum levels were reduced by anti-TNF in the infliximab cohort (week 6 and 14) and in the adalimumab cohort (week 8). VICM was lower in the responders compared with the nonresponders [infliximab: Week 6, P<0.05; area under the curve (AUC)=0.90; adalimumab: Week 1, P<0.01 (AUC=0.91), and week 8, P<0.05 (AUC=0.86)], and were able to predict response to treatment after 1 week of treatment with an odds ratio of 42.5. Conclusions: The VICM biomarker was time dependently reduced in CD patients responding to anti-TNF treatment. We suggest that VICM may be used as a marker for monitoring early response to anti-TNF in patients with CD

The NuRD chromatin–remodeling complex regulates signaling and repair of DNA damage

NuRD is recruited to DNA double-strand breaks, where it promotes RNF8/RNF168 histone ubiquitylation and accumulation of DNA repair factors (see also related paper by Larsen et al. in this issue)

Long noncoding RNA H19X is a key mediator of TGF-beta-driven fibrosis

TGFβ is a master regulator of fibrosis, driving the differentiation of fibroblasts into apoptosis resistant myofibroblasts and sustaining the production of extracellular matrix (ECM) components. Here, we identify the nuclear lncRNA H19X as a master regulator of TGFβ-driven tissue fibrosis. H19X was consistently upregulated in a wide variety of human fibrotic tissues and diseases and was strongly induced by TGFβ, particularly in fibroblasts and fibroblast-related cells. Functional experiments following H19X silencing revealed that H19X is an obligatory factor for the TGFβ-induced ECM synthesis as well as differentiation and survival of ECM-producing myofibroblasts. We showed that H19X regulates DDIT4L gene expression, specifically interacting with a region upstream of DDIT4L gene and changing the chromatin accessibility of a DDIT4L enhancer. These events resulted in transcriptional repression of DDIT4L and, in turn, in increased collagen expression and fibrosis. Our results shed light on key effectors of the TGFβ-induced ECM remodeling and fibrosis

Evaluating the efficacy of potential drugs for intestinal fibrosis using precision-cut tissue slices

Intestinal fibrosis (IF) is a common complication in Crohn's disease. Currently, there are no drugs registered to treat IF and the sole therapy is intestinal resection. Transforming growth factor (TGF)-beta and platelet-derived growth factor (PDGF) play a key role in IF and are the main targets for potential treatment. Recently, we developed a novel model for the early onset of IF using precision-cut intestinal slices (PCIS). Our objective was to investigate the antifibrotic effect of some potential antifibrotic compounds, including TGF-beta and PDGF-pathway inhibitors, by using the murine PCIS fibrosis model. Murine PCIS were incubated up to 48 h. The viability was assessed by evaluating the ATP content of the PCIS. Gene expression of the fibrosis markers pro-collagen 1a1 (Col1a1), heat shock protein 47 (Hsp47) and fibronectin (Fn2) were determined by qPCR. The effects of antifibrotic drugs mainly inhibiting the TGF-beta pathway: valproic acid (VPA), tetrandrine (Tet), pirfenidone (Pir), and LY2109761 (LY) and mainly inhibiting the PDGF pathway: imatinib (Ima), sorafenib (Sor), and sunitinib (Sun) were determined at the maximal non-toxic concentrations. Murine PCIS remained viable up to 48 h of incubation and showed increased gene expression of the fibrosis markers (Col1a1, 0.6; Hsp47, 4.0 and Fn2, 4.4 fold). After 48 h, VPA and Tet down-regulated Hsp47 gene expression 2.0 and 1.7 fold, respectively. Furthermore, Fn2 gene expression was also decreased 2.1 fold by Tet. Meanwhile, Pir decreased Col1a1, Hsp47, and Fn2 gene expression 2.2, 1.5, and 1.2 fold, respectively. All investigated markers of fibrosis were down-regulated by LY (Col1a1, 9.0; Hsp47, 1.9 and Fn2, 2.7 fold). Sun decreased the expression of Col1a1, 1.6; Hsp47, 3.3 and Fn2, 2.3 fold, while Sor only down-regulated Hsp47, 1.3 fold. In contrast, Ima did not affect the expression of fibrosis markers. From the compounds studied, the TGF-beta-inhibitors; Tet, Pir, and LY and only one PDGF-inhibitor, Sun, showed potential antifibrotic effect on gene expression of fibrosis markers in murine PCIS. Thus, PCIS is a promising model to evaluate the antifibrotic effect of potential drugs for intestinal fibrosis

Computationally guided in-vitro vascular growth model reveals causal link between flow oscillations and disorganized neotissue

Disturbed shear stress is thought to be the driving factor of neointimal hyperplasia in blood vessels and grafts, for example in hemodialysis conduits. Despite the common occurrence of neointimal hyperplasia, however, the mechanistic role of shear stress is unclear. This is especially problematic in the context of in situ scaffold-guided vascular regeneration, a process strongly driven by the scaffold mechanical environment. To address this issue, we herein introduce an integrated numerical-experimental approach to reconstruct the graft-host response and interrogate the mechanoregulation in dialysis grafts. Starting from patient data, we numerically analyze the biomechanics at the vein-graft anastomosis of a hemodialysis conduit. Using this biomechanical data, we show in an in vitro vascular growth model that oscillatory shear stress, in the presence of cyclic strain, favors neotissue development by reducing the secretion of remodeling markers by vascular cells and promoting the formation of a dense and disorganized collagen network. These findings identify scaffold-based shielding of cells from oscillatory shear stress as a potential handle to inhibit neointimal hyperplasia in grafts