Losartan reduces trinitrobenzene sulphonic acid-induced colorectal fibrosis in rats

Evaluation effect of alginate hydrogel containing losartan on wound healing and gene expression

Skin tissue engineering has become an increasingly popular alternative to conventional treatments for skin injuries. Hydrogels, owing to their advantages have become the ideal option for wound dressing, and they are extensively employed in a mixture of different drugs to accelerate wound healing. Sodium alginate is a readily available natural polymer with advantages such as bio-compatibility and a non-toxicological nature that is commonly used in hydrogel form for medical applications such as wound repair and drug delivery in skin regenerative medicine. Losartan is a medicine called angiotensin receptor blocker (ARB) that can prevent fibrosis by inhibiting AT1R (angiotensin II type 1 receptor). In this research, for the first time, three-dimensional scaffolds based on cross-linked alginate hydrogel with CaCl2 containing different concentrations of losartan for slow drug release and exudate absorption were prepared and characterized as wound dressing. Alginate hydrogel was mixed with 10, 1, 0.1, and 0.01 mg/mL of losartan, and their properties such as morphology, chemical structure, water uptake properties, biodegradability, stability assay, rheology, blood compatibility, and cellular response were evaluated. In addition, the therapeutic efficiency of the developed hydrogels was then assessed in an in vitro wound healing model and with a gene expression. The results revealed that the hydrogel produced was very porous (porosity of 47.37 ± 3.76 µm) with interconnected pores and biodegradable (weight loss percentage of 60.93 ± 4.51% over 14 days). All hydrogel formulations have stability under various conditions. The use of CaCl2 as a cross-linker led to an increase in the viscosity of alginate hydrogels. An in vitro cell growth study revealed that no cytotoxicity was observed at the suggested dosage of the hydrogel. Increases in Losartan dosage, however, caused hemolysis. In vivo study in adult male rats with a full-thickness model showed greater than 80% improvement of the primary wound region after 2 weeks of treatment with alginate hydrogel containing 0.1 mg/mL Losartan. RT-PCR and immunohistochemistry analysis showed a decrease in expression level of TGF-β1 and VEGF in treatment groups. Histological analysis demonstrated that the alginate hydrogel containing Losartan can be effective in wound repair by decreasing the size of the scar and tissue remodeling, as evidenced by future in vivo studies.

Emerging therapeutics for the management of intestinal fibrosis and strictures

Chronic intestinal inflammation in patients with inflammatory bowel disease (IBD) can lead to the development of fibrosis and the formation of strictures. Endoscopic balloon dilation and surgical resection are currently the only available treatments for fibrotic strictures. However, both strategies are associated with potential complications and high rates of stricture recurrence, necessitating additional procedures and/or multiple surgical resections. IBD therapeutic modalities aimed at inflammation, including anti-inflammatory agents, such as corticosteroids, biologics and small molecules, have shown limited efficacy in altering the natural history of strictures, ameliorating fibrosis progression, or preventing recurrences. New and innovative therapeutic approaches targeted at fibrosis are urgently needed. Herein, we provide an overview of emerging therapeutics, including novel drug delivery systems, for the management of intestinal fibrosis and strictures.

Heterogeneity in protocols and outcomes to study the effect of renin-angiotensin system blockers in inflammatory bowel disease: A systematic review

BACKGROUND

The renin-angiotensin system (RAS) has been associated with inflammatory bowel disease (IBD), supporting translational relevance of RAS blockers. Comparability of study design/outcomes is fundamental for data analysis/discussion.

OBJECTIVES

We aimed at evaluating the heterogeneity among protocols and outcomes to study the effect of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in IBD.

METHODS

This study was performed and reported in accordance with the Cochrane recommendations and PRISMA (PROSPERO-CRD42022323853). Systematic searches were performed in PubMed, Scopus and Web of Science. Studies that met the inclusion criteria were selected. Quality assessment of the studies was done with the SYRCLES's risk of bias tools for animal studies.

RESULTS

Thirty-five pre-clinical studies and six clinical studies were included. Chemical induction of colitis was the most used model, but variable doses of the induction agent were reported. All studies reported at least a disease activity index, a macroscopic score, or a histologic assessment, but these scores were methodologically heterogeneous and reported for different characteristics. Great heterogeneity was also found in drug interventions. Inflammatory markers assessed as outcomes were different across studies.

CONCLUSION

Lack of standardization of protocols and outcomes among studies threatens the evidence on how RAS blockers influence IBD outcomes.

Precision medicine in monogenic inflammatory bowel disease: proposed mIBD REPORT standards

Owing to advances in genomics that enable differentiation of molecular aetiologies, patients with monogenic inflammatory bowel disease (mIBD) potentially have access to genotype-guided precision medicine. In this Expert Recommendation, we review the therapeutic research landscape of mIBD, the reported response to therapies, the medication-related risks and systematic bias in reporting. The mIBD field is characterized by the absence of randomized controlled trials and is dominated by retrospective observational data based on case series and case reports. More than 25 off-label therapeutics (including small-molecule inhibitors and biologics) as well as cellular therapies (including haematopoietic stem cell transplantation and gene therapy) have been reported. Heterogeneous reporting of outcomes impedes the generation of robust therapeutic evidence as the basis for clinical decision making in mIBD. We discuss therapeutic goals in mIBD and recommend standardized reporting (mIBD REPORT (monogenic Inflammatory Bowel Disease Report Extended Phenotype and Outcome of Treatments) standards) to stratify patients according to a genetic diagnosis and phenotype, to assess treatment effects and to record safety signals. Implementation of these pragmatic standards should help clinicians to assess the therapy responses of individual patients in clinical practice and improve comparability between observational retrospective studies and controlled prospective trials, supporting future meta-analysis.

Repurposing of RAS-Pathway Mediated Drugs for Intestinal Inflammation Related Diseases for Treating SARS-CoV-2 Infection

Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) is an emerging zoonotic virus, which causes Coronavirus Disease 2019 (COVID-19). Entry of coronaviruses into the cell depends on binding of the viral spike (S) proteins to cellular receptors Angiotensin-converting enzyme 2 (ACE2). The virus-mediated reduction of ACE2/Ang1-7 causes flooding of inflammatory cytokines. A similar scenario of hyper immunologic reaction has been witnessed in the context of Intestinal Inflammatory Diseases (IIDs) with the deregulation of ACE2. This review summarizes several IIDs that lead to such susceptible conditions. It discusses suitable mechanisms of how ACE2, being a crucial regulator of the Renin-Angiotensin System (RAS) signaling pathway, can affect the physiology of intestine as well as lungs, the primary site of SARS-CoV-2 infection. ACE2, as a SARS-CoV-2 receptor, establishes a critical link between COVID-19 and IIDs. Intercessional studies targeting the RAS signaling pathway in patients may provide a novel strategy for addressing the COVID-19 crisis. Hence, the modulation of these key RAS pathway members can be beneficial in both instances. However, it's difficult to say how beneficial are the ACE inhibitors (ACEI)/ Angiotensin II type-1 receptor blockers (ARBs) during COVID-19. As a result, much more research is needed to better understand the relationship between the RAS and SARS-CoV-2 infection.

What do we know about the renin angiotensin system and inflammatory bowel disease?

INTRODUCTION

The renin-angiotensin system (RAS) is an important homeostatic pathway, with emerging evidence for the impact of its components on inflammation and fibrosis in gastrointestinal tissues. This review aims to review current knowledge of the physiological mechanism of RAS in inflammatory bowel disease (IBD), and potential therapeutic implications.

AREAS COVERED

An extensive online literature review including Pubmed, Medline, and Google Scholar was undertaken. Discussion on the components of the RAS, localization, and physiological functions in the gastrointestinal tract, preclinical, and clinical data in IBD, and the relation with SARS-Cov-2 are covered in this review.

EXPERT OPINION

RAS inhibition may have a role as anti-fibrotic adjunct therapy. Targeting the local gastrointestinal RAS with novel modes of delivery may be a target for future therapeutics for IBD, given the widespread availability and safety of current options as utilized in other diseases. Further insight into the mechanism and downstream effects of gastrointestinal ACE2 may lead to a better understanding of the pathogenesis of IBD.

Losartan ameliorates renal interstitial fibrosis through metabolic pathway and Smurfs-TGF-β/Smad

The genesis and development of renal fibrosis involve a variety of pathways closely related to inflammation, cytokines, oxidative stress and metabolic abnormalities. Renal fibrosis is the result of a complex combination of a variety of lesions. Epithelial-mesenchymal transdifferentiation (EMT) of renal tubular epithelial cells is considered the key to renal fibrosis. Losartan is a typical Angiotensin II (ANG II) receptor antagonist and relaxes blood vessels. In this study, we investigated the effects of losartan on Unilateral Ureteral Obstruction (UUO) model mice by studying the changes in the TGF-β/Smad and metabolomics. Male C57BL/6 J mice were intervened with the UUO model and given losartan (10, 20, 30 mg/kg/d) for 28 consecutive days. The results showed that losartan could reduce UUO-induced abnormal serum metabolic spectrum and renal function. It could also improve renal tubular-interstitial injury and fibrosis by reducing tubulointerstitial dilation and collagen deposition. In addition, losartan promoted the expression of Smurf2 and Smurf1, i.e., Smad7 and E3 ubiquitin-linked enzymes, in the nucleus to degrade the type I receptor of TGF-β1 (TβR-I) and P-Smad2/3 to inhibit renal tubular epithelial cells EMT. In summary, these findings indicated that losartan could regulate the TGF-β/Smad and metabolic pathway in UUO model mice through ubiquitination to reduce renal fibrosis.

Therapeutic Targeting of Intestinal Fibrosis in Crohn's Disease

Intestinal fibrosis is one of the most threatening complications of Crohn’s disease. It occurs in more than a third of patients with this condition, is associated with increased morbidity and mortality, and surgery often represents the only available therapeutic option. The mechanisms underlying intestinal fibrosis are partly known. Studies conducted so far have shown a relevant pathogenetic role played by mesenchymal cells (especially myofibroblasts), cytokines (e.g., transforming growth factor-β), growth factors, microRNAs, intestinal microbiome, matrix stiffness, and mesenteric adipocytes. Further studies are still necessary to elucidate all the mechanisms involved in intestinal fibrosis, so that targeted therapies can be developed. Although several pre-clinical studies have been conducted so far, no anti-fibrotic therapy is yet available to prevent or reverse intestinal fibrosis. The aim of this review is to provide an overview of the main therapeutic targets currently identified and the most promising anti-fibrotic therapies, which may be available in the near future.

Effect of Candesartan and Ramipril on Liver Fibrosis in Patients with Chronic Hepatitis C Viral Infection: A Randomized Controlled Prospective Study

Objective: This study aimed at evaluating the effects of candesartan and ramipril on liver fibrosis in patients with chronic hepatitis C. Methods: This randomized controlled prospective study involved 64 patients with chronic hepatitis C and liver fibrosis. Participants were randomized into 3 groups: group I (control group; n = 21), members of which received traditional therapy only; group 2 (ramipril group; n = 21), members of which received traditional therapy plus 1.25 mg/d oral ramipril; and group 3 (candesartan group; n = 22), members of which received traditional therapy plus 8 mg/d oral candesartan. Patients were assessed at baseline and 6 months after intervention through measuring of liver stiffness (Fibro-Scan; Echosens, Paris, France); evaluation of the serum levels of hyaluronic acid and transforming growth factor beta-1; and calculation of indices of liver fibrosis, including fibrosis index based on the 4 factors and aspartate transaminase-to-platelet-ratio index. Data were analyzed using paired t test and 1-way ANOVA followed by Tukey's honest significant difference test for multiple pairwise comparisons. Results: At baseline, the 3 study groups were statistically similar in demographic and laboratory data. After treatment, the 3 study groups showed significant decrease in liver stiffness, serum levels of hyaluronic acid and transforming growth factor beta-1, and indices of liver fibrosis compared with baseline data (P < 0.001). Six months after treatment, patients taking ramipril and candesartan showed significant improvement in all measured parameters compared with the control group. Additionally, the candesartan-treated group showed significant decrease in liver stiffness, biomarkers, and indices of liver fibrosis compared with ramipril recipients. Conclusions: The administration of ramipril and candesartan in patients with chronic hepatitis C with hepatic fibrosis was well tolerated and effective in improving liver fibrosis. angiotensin II receptor 1 (AT1) antagonist candesartan maintained antifibrotic effects more effectively than ramipril and may represent a safe and effective therapeutic strategy for liver fibrosis in patients with chronic liver diseases. ClinicalTrials.gov identifier: NCT03770936. (Curr Ther Res Clin Exp. 2022; 83:XXX-XXX) © 2022 Elsevier HS Journals, Inc.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

Therapeutic Targeting of Nrf2 Signaling by Maggot Extracts Ameliorates Inflammation-Associated Intestinal Fibrosis in Chronic DSS-Induced Colitis

Intestinal fibrosis is induced by excessive myofibroblast proliferation and collagen deposition, which has been regarded as a general pathological feature in inflammatory bowel disease (IBD). Therefore, identifying clinical markers and targets to treat and prevent intestinal fibrosis is urgently needed. The traditional Chinese medicine maggot, commonly known as “wu gu chong”, has been shown to reduce oxidative stress and alleviate inflammation in chronic colitis. This study investigated the mechanisms underlying the effects of maggot extract (ME) on inflammation-associated intestinal fibrosis in TGF-β1-stimulated human intestinal fibroblasts (CCD-18Co cells) and dextran sodium sulphate (DSS)-induced chronic colitis murine model. To assess the severity of inflammation and fibrosis, histological and macroscopic evaluation were carried out. The results showed that ME was a significant inhibitor of body weight loss and colon length shortening in mice with chronic colitis. In addition, ME suppressed the intestinal fibrosis by downregulating TGF-β1/SMADs pathway via upregulation of Nrf2 expression at both protein and mRNA levels. ME markedly increased the expression of Nrf2, thus resulting in a higher level of HO-1. After treatment with Nrf2 inhibitor (ML385) or siRNA-Nrf2 for deactivating Nrf2 pathway, the protective effects of ME were abolished both in vitro and in vivo. Moreover, the histopathological results for the major organs of DSS mice treated with ME showed no signs of clinically important abnormalities. Treatment with ME had no effect on the viability of CCD-18Co cells, suggesting its low in vitro cytotoxicity. Furthermore, ME could mediate intestine health by keeping the balance of the gut microbes through the enhancement of beneficial microbes and suppression of pathogenic microbes. In conclusion, this is the first ever report demonstrating that ME ameliorates inflammation-associated intestinal fibrosis by suppressing TGF-β1/SMAD pathway via upregulation of Nrf2 expression. Our findings highlight the potential of Nrf2 as an effective therapeutic target for alleviating intestinal fibrosis.

Beyond biologics: advanced therapies in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are conditions characterized by persistent and relapsing inflammation involving the gastrointestinal tract at various levels. Although the etiopathogenesis of IBDs is partially understood, a deregulated activation of intestinal immune cells in genetically susceptible patients is thought to be key for the disease onset and evolution. Artificial Nutrition might affect favorably on inflammation and related cytokine storm. However, the discovery of monoclonal antibodies blocking pro-inflammatory cytokines (e.g., tumor necrosis factor-α - TNF-α) changed radically the management of IBDs. Anti-TNF-α agents represent the prototype molecule of the so-called 'biologics' / 'biologicals'. These compounds have significantly improved the therapeutic management of IBDs refractory to standard medications, achieving clinical remission, mucosal healing and preventing extra-intestinal manifestations. However, about 50% of patients treated with biologicals experienced drawbacks, such as primary failure or loss of response, requiring new effective treatments. Translational studies have identified other pathways, different from the TNF-α blockade, and new molecules, e.g. sphingosine-1-phosphate agonists and the JAK kinase inhibitors, have been proposed as potential therapeutic options for IBDs. These novel therapeutic approaches represent a "new era" of IBD management, especially for patients poorly responsive to biologicals. In this review, we will summarize the new pharmacological strategies to treat IBDs, and discuss their effectiveness and safety, along with future perspectives for IBD treatment.

Renin-angiotensin system in intestinal inflammation-Angiotensin inhibitors to treat inflammatory bowel diseases?

Inflammatory bowel diseases (IBDs) are chronic disorders of the gastrointestinal tract, which manifest in recurring gastrointestinal inflammation. The current treatment options of IBD are not curative and are lacking in aspects like prevention of fibrosis. New treatment options are needed to fulfil the unmet needs and provide alternatives to drugs with resistances and side effects. Drugs targeting the renin-angiotensin system (RAS), besides being antihypertensive, also possess anti-inflammatory and antifibrotic properties and could offer an inexpensive alternative to control inflammation and fibrosis in the gut. RAS inhibitors have been effective in preventing and alleviating colitis in preclinical studies, but available human data are still sparse. This review outlines the pathophysiological functions of RAS in the gut and summarizes preclinical studies utilizing pharmacological RAS inhibitors in the treatment of experimental colitis. We discuss the alterations in intestinal RAS and the available evidence of the benefits of RAS inhibitors for IBD patients. Retrospective studies comparing IBD patients using ACE inhibitors or angiotensin II receptor blockers have provided optimistic results regarding a milder disease course and fewer hospitalizations and corticosteroid use in patients using RAS inhibitors. Prospective studies are needed to evaluate the effectiveness of these promising medications in the treatment of IBD.

Losartan prevents bladder fibrosis and protects renal function in rat with neurogenic paralysis bladder

AIMS

To investigate the effect of losartan on preventing bladder fibrosis and protecting renal function in rats with neurogenic paralysis bladder (NPB).

MATERIALS AND METHODS

Rats were assigned to the transecting spinal nerves group (TSNG), transecting spinal nerves + losartan group (LSTG), and control group (CG). On Day 32 postsurgery, bladder capacity (BC), bladder compliance (ΔC), bladder leakage pressure (P_ves.leak ) of TSNG and LSTG while BC, ΔC, and bladder threshold pressure (P_ves.thre ) of CG were measured by cystometry in each cohort. Renal function and the expression quantity of Angiotensin Ⅱ (Ang II) in blood were detected, in addition Ang II, Ang II Type 1 receptor (AT1), transformation growth factor β1 (TGFβ1), Collagen Ⅲ, and collagen fibrin in the bladder tissue were detected too.

RESULTS

ΔC in TSNG and LSTG decreased significantly compared to the CG. P_ves.leak in TSNG and LSTG were significantly higher than P_ves.thre in CG. Renal function of both TSNG and LSTG decreased significantly compared with the CG, but renal function in LSTG was better than in TSNG. Ang Ⅱ in blood and bladder tissue in TSNG and LSTG increased significantly compared with CG. AT1 was expressed in the bladder tissue of all rats. The TGFβ1, Collagen Ⅲ, and collagen fibrin expression level increased significantly in TSNG compared with LSTG and CG, while these levels were not significantly different between CG and LSTG.

CONCLUSION

Losartan might prevent NPB fibrosis by stopping the upregulated signaling of Ang II/AT1/TGFβ1 and consequently may reduce kidney damage from occurring.

Prevention and Treatment of Stricturing Crohn's Disease - Perspectives and Challenges

Introduction: Fibrostenosis is a hallmark of Crohn's disease (CD), remains a challenge in today's clinical management of inflammatory bowel disease patients and represents a key event in the disease course necessitating improved preventative strategies and a multidisciplinary approach to diagnosis and management. With the advent of anti-fibrotic therapies and well-defined clinical endpoints for stricturing CD, there is promise to impact the natural history of disease.Areas covered: This review summarizes current evidence in the natural history of stricturing Crohn's disease, discusses management approaches as well as future perspectives on intestinal fibrosis.Expert opinion: Currently, there are no specific therapies to prevent progression to fibrosis or to treat it after it becomes clinically apparent. In addition to the international effort by the Stenosis Therapy and Anti-Fibrotic Research (STAR) consortium to standardize definitions and propose endpoints in the management of stricturing CD, further research to improve our understanding of mechanisms of intestinal fibrosis will help pave the way for the development of future anti-fibrotic therapies.

Role of Interleukin-17 in Pathogenesis of Intestinal Fibrosis in Mice

BACKGROUND

The level of interleukin (IL)-17 is commonly increased in serum and intestinal mucosa of patients with inflammatory bowel disease, especially Crohn's disease with intestinal stricture. However, the role of IL-17 in the pathogenesis of intestinal fibrosis and the effect of anti-IL-17 treatment on intestinal fibrosis remain unclear; these issues are studied in vivo in this study.

METHOD

A total of 24 wild female Balb/c mice (18-22 g) were randomly divided into three groups: (1) control group, (2) 2,4,6-trinitrobenzenesulfonic acid (TNBS) + immunoglobulin G (IgG) group, and (3) TNBS + anti-IL-17 group. The levels of IL-17, IL-1β, transforming growth factor (TGF)-β1, and tumor necrosis factor (TNF)-α in blood and of collagen 3 and IL-17 in gut were measured by enzyme-linked immunosorbent assay (ELISA). The messenger RNA (mRNA) levels of collagen 3, IL-17, TNF-α, tissue inhibitor of metalloproteinase (TIMP)-1, and matrix metalloproteinase (MMP)-2 in gut were measured by reverse-transcription polymerase chain reaction. The protein expression of IL-17, collagen 3, TNF-α, TIMP-1, and MMP-2 were measured by immunoblot analysis. Collagen deposition was evaluated by standard hematoxylin and eosin and Masson's trichrome staining.

RESULTS

The profibrogenic cytokines IL-17, IL-1β, TGF-β1, and TNF-α in serum, mRNA levels of collagen 3, IL-17, TNF-α, TIMP-1, and MMP-2, and protein levels of IL-17, collagen 3, TNF-α, TIMP-1, and MMP-2 in gut were upregulated in TNBS-induced intestinal fibrosis mice. Treatment with anti-IL-17 antibody significantly alleviated intestinal fibrosis and reduced both mRNA and protein levels of collagen 3, TNF-α, TIMP-1, and MMP-2. The levels of profibrogenic cytokines IL-1β, TGF-β1, and TNF-α were also decreased in mice treated with anti-IL-17 antibody.

CONCLUSIONS

IL-17 contributes to the pathogenesis of intestinal fibrosis, and anti-IL-17 therapy may weaken this effect by downregulating expression of profibrogenic cytokines and disturbing the MMP/TIMPs balance.

Wu-Mei-Wan ameliorates chronic colitis-associated intestinal fibrosis through inhibiting fibroblast activation

ETHNOPHARMACOLOGICAL RELEVANCE

Wu-Mei-Wan (WMW), a classic traditional Chinese herb medicine, is one of the most important formulations to treat digestive diseases from ancient times to the present. Previous study showed that WMW has satisfactory curative effects on experimental colitis, which motivating the application of WMW on colitis-associated complications.

AIM OF THE STUDY

Intestinal fibrosis is usually considered to be a common complication of inflammatory bowel disease (IBD), particularly Crohn's disease (CD). Currently, no effective preventive measures or medical therapies are available for that. This work was designed to evaluate the effect and related mechanism of WMW on chronic colitis-associated intestinal fibrosis mice model.

MATERIALS AND METHODS

The chronic colitis-associated intestinal fibrosis mice model was established by weekly intrarectal injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS). The mice survival rate, disease activity index (DAI), colon length and histological score were examined to assess the therapeutic effect of WMW. Masson's trichrome staining, hydroxyproline assay, immunohistochemical staining and western blot analysis were used to evaluate fibrosis level. Colon inflammation was determined by ELISA and immunofluorescence staining. Immunofluorescence staining was used to evaluate fibroblasts proliferation and epithelial to mesenchymal transition (EMT), and the expression of key molecules in fibrosis was analyzed by western blot.

RESULTS

Here we showed that WMW alleviates chronic colitis with improved survival rate, DAI, colon length and histological score. WMW inhibited the progression of intestinal fibrosis, decreased the expression of various fibrosis markers, such as α-SMA, collagen I, MMP-9 and fibronectin. In addition, WMW treatment reduced cytokines IL-6 and IFN-γ, and downregulated proinflammatory NF-κBp65 and STAT3 signaling pathways. Importantly, administration of WMW led to the inhibition of colon fibroblast proliferation and EMT, which are important mediators during fibrosis. Several key profibrotic pathways, including TGF-β/Smad and Wnt/β-catenin pathways, were downregulated by WMW treatment.

CONCLUSION

Our work demonstrated that WMW can prevent intestinal fibrosis and the mechanisms involved may be related to the inhibition of colon fibroblasts activation.

Changes to the gut microbiota induced by losartan contributes to its antihypertensive effects

BACKGROUND AND PURPOSE

Hypertension is associated with gut dysbiosis. Here we have evaluated the effects of the angiotensin receptor antagonist losartan on gut microbiota in spontaneously hypertensive rats (SHR) to assess their contribution to its antihypertensive effects.

EXPERIMENTAL APPROACH

Twenty-week-old Wistar Kyoto rats (WKY) and SHR were treated with losartan for 5 weeks (SHR-losartan). Faecal microbiota transplantation (FMT) was performed from donor SHR-losartan group to recipient untreated-SHR. Blood pressure (BP) was measured using tail-cuff plethysmography. Composition of the gut microbiota was assessed by amplification of the V3-V4 region of 16S rRNA gene. T cells were analysed in gut/aorta by flow cytometry.

KEY RESULTS

Faeces from SHR showed gut dysbiosis, characterised by higher Firmicutes/Bacteroidetes ratios, lower acetate- and higher lactate-producing bacteria, and lower levels of strict anaerobic bacteria, effects which were restored to normal by losartan. Improvement of gut dysbiosis was linked to higher colonic integrity and lower sympathetic drive in the gut. In contrast, hydralazine reduced BP, but it neither restored gut dysbiosis nor colonic integrity. FMT from SHR-losartan to SHR reduced BP, improved the aortic endothelium-dependent relaxation to ACh, and reduced NADPH oxidase activity. These vascular changes were accompanied by both increased Treg and decreased Th17 cell populations in the vascular wall.

CONCLUSION AND IMPLICATIONS

In SHR, losartan treatment reduced gut dysbiosis and sympathetic drive in the gut, thus improving gut integrity. The changes induced by losartan in gut microbiota contributed, in part, to protecting the vasculature and reducing BP, possibly by modulating the immune system in the gut.

Impact of Angiotensin II Signaling Blockade on Clinical Outcomes in Patients with Inflammatory Bowel Disease

BACKGROUND

Preclinical data demonstrate that activation of the renin-angiotensin system (RAS) contributes to mucosal inflammation, and RAS inhibition by angiotensin-converting-enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) improves colitis in animal models. Less is known regarding the effects of RAS inhibition on clinical outcomes in inflammatory bowel disease (IBD) patients.

AIM

Evaluate the impact of ACEI and ARB on clinical outcomes in IBD.

METHODS

Rates of IBD-related hospitalizations, operations, and corticosteroid use were evaluated retrospectively in two groups. First, 111 IBD patients taking an ACEI or ARB were compared to nonusers matched 1:1 based on sex, age, diagnosis, disease location, and hypertension diagnosis. Second, outcomes in a cohort of 130 IBD patients were compared prior to and during ACEI/ARB exposure.

RESULTS

Compared to matched controls, all IBD patients together with ACEI/ARB exposure had fewer hospitalizations (OR 0.26, p < 0.01), operations (OR 0.08, p = 0.02), and corticosteroid prescriptions (OR 0.5, p = 0.01). Comparing outcomes before and during ACEI/ARB use, there were no differences in hospitalizations, operations, or corticosteroid use for all IBD patients together, but patients with UC had increased hospitalizations (0.08 pre- vs. 0.16 during ACEI/ARB exposure, p = 0.03) and decreased corticosteroid use (0.24 pre-ACEI/ARB vs. 0.12 during ACEI/ARB exposure, p < 0.01) during ACEI/ARB use.

CONCLUSIONS

IBD patients with ACEI/ARB exposure had fewer hospitalizations, operations, and corticosteroid use compared to matched controls. No differences in outcomes were observed in individuals on ACEI/ARB therapy when compared to a period of time prior to medication exposure.

Losartan Alleviates Renal Fibrosis and Inhibits Endothelial-to-Mesenchymal Transition (EMT) Under High-Fat Diet-Induced Hyperglycemia

The endothelial-to-mesenchymal transition (EMT) of glomerular vascular endothelial cells is considered to be pivotal in diabetic nephropathy (DN). The risk of DN can be decreased by losartan, but the potential molecular mechanism(s) are not fully understood. Extensive data show that the EMT occurs in proximal tubular endothelial cells resulting in an endothelial phenotype switch (fibrotic matrix accumulation), consequently enhancing the development of renal interstitial fibrosis. Here, we found that losartan significantly ameliorated DN-induced renal fibrosis progression via inhibition of the EMT in mice. In vivo experiments suggested that losartan significantly alleviated microalbuminuria and pathologic changes under high-fat diet-induced hyperglycemia. Immunohistochemistry indicated that losartan suppressed the EMT in glomeruli. In addition, losartan decreased oxidative stress damage and inhibited the transforming growth factor (TGF)-β1/Smad pathway. Furthermore, consistent changes were detected in vitro where losartan markedly inhibited the EMT and TGF-β1/Smad pathway induced by high glucose in glomerular endothelial cells. Together, these results suggested that losartan could alleviate the EMT in glomeruli via inhibition of oxidative stress damage and the TGF-β1/Smad signaling pathway under hyperglycemia.

Biological therapies for eosinophilic gastrointestinal diseases

The scientific basis and the clinical application of mAb therapies that target specific immunologic pathways for eosinophilic gastrointestinal diseases are areas of active interest. There is a growing recognition of a subset of patients with eosinophilic esophagitis whose disease does not respond well to topical steroids or elimination diets. In addition, long-term use of corticosteroids presents possible risks that are currently being evaluated. Systemic therapy with a biologic agent offers potential advantages as a global approach that could limit the need for multiple, locally active medical therapies and allergen avoidance. The identification of novel biologic strategies is ongoing, and the recent validation of instruments and outcome measures to assess disease activity has proved essential in demonstrating efficacy. Studies using biologics that target IL-13 pathways in the treatment of eosinophilic esophagitis have demonstrated substantial promise.

IL-17-driven intestinal fibrosis is inhibited by Itch-mediated ubiquitination of HIC-5

Intestinal fibrosis is a major complication in inflammatory bowel diseases, but the regulatory mechanism that inhibits fibrosis remains unclear. Here we demonstrate that Itch^-/-myofibroblasts express increased amounts of profibrotic collagen type I and α-SMA in response to IL-17. Mechanistically, we demonstrate that Itch directly binds to HIC-5 and targets it for K63-linked ubiquitination to inhibit IL-17-driven intestinal fibrosis. Reconstitution of Itch^-/- myofibroblasts with wild-type Itch but not the Itch-C830A mutant normalized the expression of profibrotic genes. Similarly, shRNA-mediated inhibition of HIC-5 normalized the expression of profibrotic gene expression. Thus, we have uncovered a novel mechanism by which Itch negatively regulates intestinal fibrosis.

Treatment of Intestinal Fibrosis in Experimental Inflammatory Bowel Disease by the Pleiotropic Actions of a Local Rho Kinase Inhibitor

BACKGROUND

Intestinal fibrosis resulting in (sub)obstruction is a common complication of Crohn's disease (CD). Rho kinases (ROCKs) play multiple roles in TGFβ-induced myofibroblast activation that could be therapeutic targets. Because systemic ROCK inhibition causes cardiovascular side effects, we evaluated the effects of a locally acting ROCK inhibitor (AMA0825) on intestinal fibrosis.

METHODS

Fibrosis was assessed in mouse models using dextran sulfate sodium (DSS) and adoptive T-cell transfer. The in vitro and ex vivo effects of AMA0825 were studied in different cell types and in CD biopsy cultures.

RESULTS

ROCK is expressed in fibroblastic, epithelial, endothelial, and muscle cells of the human intestinal tract and is activated in inflamed and fibrotic tissue. Prophylactic treatment with AMA0825 inhibited myofibroblast accumulation, expression of pro-fibrotic factors, and accumulation of fibrotic tissue without affecting clinical disease activity and histologic inflammation in 2 models of fibrosis. ROCK inhibition reversed established fibrosis in a chronic DSS model and impeded ex vivo pro-fibrotic protein secretion from stenotic CD biopsies. AMA0825 reduced TGFβ1-induced activation of myocardin-related transcription factor (MRTF) and p38 mitogen-activated protein kinase (MAPK), down-regulating matrix metalloproteinases, collagen, and IL6 secretion from fibroblasts. In these cells, ROCK inhibition potentiated autophagy, which was required for the observed reduction in collagen and IL6 production. AMA0825 did not affect pro-inflammatory cytokine secretion from other ROCK-positive cell types, corroborating the selective in vivo effect on fibrosis.

CONCLUSIONS

Local ROCK inhibition prevents and reverses intestinal fibrosis by diminishing MRTF and p38 MAPK activation and increasing autophagy in fibroblasts. Overall, our results show that local ROCK inhibition is promising for counteracting fibrosis as an add-on therapy for CD.

Intestinal fibrosis: ready to be reversed

PURPOSE OF REVIEW

Intestinal fibrosis is a common complication of several enteropathies, with inflammatory bowel disease (IBD) being the major cause. Intestinal fibrosis affects both ulcerative colitis and Crohn's disease, and no specific antifibrotic therapy exists. This review highlights recent developments in this area.

RECENT FINDINGS

The pathophysiology of intestinal stricture formation includes inflammation-dependent and inflammation-independent mechanisms. A better understanding of the mechanisms of intestinal fibrogenesis and the availability of compounds for other nonintestinal fibrotic diseases bring clincial trials in stricturing Crohn's disease within reach.

SUMMARY

Improved understanding of its mechanisms and ongoing development of clinical trial endpoints for intestinal fibrosis will allow the testing of novel antifibrotic compounds in IBD.

Cytokine and anti-cytokine therapies in prevention or treatment of fibrosis in IBD

The frequency of fibrosing Crohn's disease (CD) is significant, with approximately 40% of CD patients with ileal disease developing clinically apparent strictures throughout their lifetime. Although strictures may be subdivided into fibrotic, inflammatory, or mixed forms, despite immunosuppressive therapy in CD patients in the form of steroids or immunomodulators, the frequency of fibrostenosing complications has still remained significant. A vast number of genetic and epigenetic variables are thought to contribute to fibrostenosing disease, including those that affect cytokine biology, and therefore highlight the complexity of disease, but also shed light on targetable pathways. Exclusively targeting fibrosis may be difficult, however, because of the relatively slow evolution of fibrosis in CD, and the potential adverse effects of inhibiting pathways involved in tissue repair and mucosal healing. Acknowledging these caveats, cytokine-targeted therapy has become the mainstay of treatment for many inflammatory conditions and is being evaluated for fibrotic disorders. The question of whether anti-cytokine therapy will prove useful for intestinal fibrosis is, therefore, acutely relevant. This review will highlight some of the current therapeutics targeting cytokines involved in fibrosis.

Distinct effects of Lactobacillus plantarum KL30B and Escherichia coli 3A1 on the induction and development of acute and chronic inflammation

Objective

Enteric bacteria are involved in the pathogenesis of ulcerative colitis. In experimental colitis, a breakdown of the intestinal epithelial barrier results in inflow of various gut bacteria, induction of acute inflammation and finally, progression to chronic colitis.

Material and methods

In the present study we compared pro-inflammatory properties of two bacterial strains isolated from human microbiome, Escherichia coli 3A1 and Lactobacillus plantarum KL30B. The study was performed using two experimental models of acute inflammation: peritonitis in mice and trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats.

Results

Both bacterial strains induced massive neutrophil infiltration upon injection into sterile peritoneal cavity. However, peritoneal exudate cells stimulated in vitro with E. coli 3A1, produced far more nitric oxide, than those stimulated with L. plantarum KL30B. Interestingly, distinct effect on the development of TNBS-induced colitis was observed after oral administration of the tested bacteria. Lactobacillus plantarum KL30B evoked strong acute colitis. On the contrary, the administration of E. coli 3A1 resulted in a progression of colitis to chronicity.

Conclusions

Our results show that distinct effects of bacterial administration on the development of ongoing inflammation is strain specific and depends on the final effect of cross-talk between bacteria and cells of the innate immune system.

AT1R blocker losartan attenuates intestinal epithelial cell apoptosis in a mouse model of Crohn's disease

Angiotensin II, which is the main effector of the renin-angiotensin system, has an important role in intestinal inflammation via the angiotensin II type 1 receptor (AT1R). The present study aimed to investigate the protective effects of the AT1R blocker losartan on 2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced colitis. Losartan was administered to male adult C57BL/6 J mice 2 weeks prior to the induction of colitis, and images of the whole colon were captured to record changes, scored according to a microscopic scoring system, and reverse transcription-quantitative polymerase chain reaction were performed in order to investigate colonic inflammation. In addition, intestinal epithelial barrier permeability was evaluated, and intestinal epithelial cell (IEC) apoptosis was measured using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and apoptosis-related protein expression levels were detected by western blotting. Losartan was able to attenuate TNBS-induced body weight loss and colonic damage. Furthermore, T helper 1-mediated proin-flammatory cytokines were suppressed by losartan, and gut permeability was largely preserved. TUNEL staining revealed reduced IEC apoptosis in the losartan-treated mice. Losartan also increased the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratio and suppressed caspase-3 induction. These results suggested that the AT1R blocker losartan may attenuate TNBS-induced colitis by inhibiting the apoptosis of IECs. The effects of losartan were partially mediated through increasing the Bcl-2/Bax ratio and subsequently suppressing the induction of the proapoptotic mediator caspase-3.

Anti-fibrotic effects of a novel small compound on the regulation of cytokine production in a mouse model of colorectal fibrosis

Intestinal fibrotic stricture is a major complication of inflammatory bowel disease. Despite its clinical importance, anti-fibrotic therapy has not been implemented. Transforming growth factor-β (TGF-β) is considered to be a major factor contributing to tissue fibrosis. We have previously shown that the administration of a small compound, HSc025, which promotes the nuclear translocation of YB-1 as a downstream effector of IFN-γ and antagonizes TGF-β/Smad signaling, improves fibrosis in several murine tissues. In this study, we evaluated the anti-fibrotic effect of HSc025 on colorectal fibrosis in TNBS-induced murine chronic colitis. Daily oral administration of HSc025 (3, 15 and 75 mg/kg) suppressed collagen production and decreased the severity of colorectal fibrosis in a dose-dependent manner. In addition, the local production of TGF-β was decreased after HSc025 treatment, whereas that of IL-13 and TNF-α was not affected. HSc025 administration maintained the level of IFN-γ production, even at a late stage when IFN-γ production was lost without the drug treatment. These results demonstrate that HSc025 could be a therapeutic candidate for intestinal fibrosis in inflammatory bowel disease that acts by altering the local production of cytokines, as well as by directly suppressing collagen production.

Medical Therapy of Fibrostenotic Crohn's Disease

Introduction

The present review serves to provide a concise overview of the current knowledge on therapeutic strategies with regard to fibrostenotic lesions in Crohn's disease.

Methods

A literature search was performed focusing on the last 5 years, and current concepts of pathophysiology, epidemiology, and treatment have been summarized.

Results

Fibrostenotic lesions in Crohn's disease are currently considered to be a consequence of the chronic inflammatory nature of the disease. Hence, therapeutic strategies are limited to the concept that early treatment of the inflammatory lesions can prevent structural changes, and to various endoscopic and surgical approaches. Direct targeting of the fibrostenotic lesion itself has not been the focus until now. This review will provide an overview of the pathophysiology and epidemiology of fibrostenotic lesions including current therapeutic approaches. Since research with regard to other organ systems and fibrosis is far more advanced, current strategies from available studies in these areas will be discussed. The results and the potential impact for Crohn's disease will be considered.

Conclusion

The vision of these approaches is to reverse structural changes and restore normal function.

Modulation of angiotensin II signaling in the prevention of fibrosis

Over the last decade, it has become clear that the role of angiotensin II extends far beyond recognized renal and cardiovascular effects. The presence of an autologous renin-angiotensin system has been demonstrated in almost all tissues of the body. It is now known that angiotensin II acts both independently and in synergy with TGF-beta to induce fibrosis via the angiotensin type 1 receptor (AT1) in a multitude of tissues outside of the cardiovascular and renal systems, including pulmonary fibrosis, intra-abdominal fibrosis, and systemic sclerosis. Interestingly, recent studies have described a paradoxically regenerative effect of the angiotensin system via stimulation of the angiotensin type 2 receptor (AT2). Activation of AT2 has been shown to ameliorate fibrosis in animal models of skeletal muscle, gastrointestinal, and neurologic diseases. Clinical reports suggest a beneficial role for modulation of angiotensin II signaling in cutaneous scarring. This article reviews current knowledge on the role that angiotensin II plays in tissue fibrosis, as well as current and potential therapies targeting this system.

Central role of IL-17/Th17 immune responses and the gut microbiota in the pathogenesis of intestinal fibrosis

PURPOSE OF REVIEW

Intestinal fibrosis is a serious, yet common, outcome in patients with inflammatory bowel disease (IBD). Despite advances in developing novel treatment modalities to control chronic gut inflammation characteristic of IBD, no effective antifibrotic therapies exist to date. As such, a deeper understanding of the molecular mechanisms underlying intestinal fibrosis and the availability of relevant animal models are critical to move this area of investigation forward.

RECENT FINDINGS

Emerging concepts in the pathogenesis of intestinal fibrosis include the central role of interleukin (IL)-17 and Th17 immune responses, although their precise contribution to chronic inflammation and IBD remains controversial. Other novel mediators of intestinal fibrosis, such as tumor necrosis factor-like ligand 1A and components of the renin-angiotensin system, support the importance of IL-17. Additionally, recent studies utilizing novel mouse models highlight the significance of the gut microbiota and link components of bacterial sensing, including nucleotide-binding oligomerization domain-containing protein 2, to IL-17/Th17 immune responses in the development of inflammation-associated intestinal fibrosis.

SUMMARY

Recent progress in identifying key mediators, novel animal models, and important mechanistic pathways in the pathogenesis of intestinal fibrosis holds promise for the development of effective antifibrotics in an area of significant, unmet clinical need.

Results of the 4th scientific workshop of the ECCO (I): pathophysiology of intestinal fibrosis in IBD

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal fibrosis in the disease course of inflammatory bowel disease (IBD). The objective was to better understand the pathophysiological mechanisms of intestinal fibrosis, to identify useful markers and imaging modalities of fibrosis in order to assess its presence and progression, and, finally, to point out possible approaches for the prevention and the treatment of fibrosis. The results of this workshop are presented in three separate manuscripts. This first section describes the most important mechanisms that contribute to the initiation and progression of intestinal fibrosis in IBD including the cellular and molecular mediators, the extracellular matrix molecules and matrix metalloproteinases/tissue inhibitors of metalloproteinases-system, the microbiota products, the role of fat, genetic and epigenetic factors, as well as the currently available experimental models. Furthermore, it identifies unanswered questions in the field of intestinal fibrosis and provides a framework for future research.

Medical therapy of stricturing Crohn's disease: what the gut can learn from other organs - a systematic review

Crohn’s disease (CD) is a chronic remitting and relapsing disease. Fibrostenosing complications such as intestinal strictures, stenosis and ultimately obstruction are some of its most common long-term complications. Despite recent advances in the pathophysiological understanding of CD and a significant improvement of anti-inflammatory therapeutics, medical therapy for stricturing CD is still inadequate. No specific anti-fibrotic therapy exists and the incidence rate of strictures has essentially remained unchanged. Therefore, the current therapy of established fibrotic strictures comprises mainly endoscopic dilation as well as surgical approaches. However, these treatment options are associated with major complications as well as high recurrence rates. Thus, a specific anti-fibrotic therapy for CD is urgently needed. Importantly, there is now a growing body of evidence for prevention as well as effective medical treatment of fibrotic diseases of other organs such as the skin, lung, kidney and liver. In face of the similarity of molecular mechanisms of fibrogenesis across these organs, translation of therapeutic approaches from other fibrotic diseases to the intestine appears to be a promising treatment strategy. In particular transforming growth factor beta (TGF-β) neutralization, selective tyrosine kinase inhibitors, blockade of components of the renin-angiotensin system, IL-13 inhibitors and mammalian target of rapamycin (mTOR) inhibitors have emerged as potential drug candidates for anti-fibrotic therapy and may retard progression or even reverse established intestinal fibrosis. However, major challenges have to be overcome in the translation of novel anti-fibrotics into intestinal fibrosis therapy, such as the development of appropriate biomarkers that predict the development and accurately monitor therapeutic responses. Future clinical studies are a prerequisite to evaluate the optimal timing for anti-fibrotic treatment approaches, to elucidate the best routes of application, and to evaluate the potential of drug candidates to reach the ultimate goal: the prevention or reversal of established fibrosis and strictures in CD patients.

The role of transforming growth factor (TGF)-β in modulating the immune response and fibrogenesis in the gut

Transforming growth factor (TGF)-β, a pleiotropic cytokine released by both immune and non-immune cells in the gut, exerts an important tolerogenic action by promoting regulatory T cell differentiation. TGF-β also enhances enterocyte migration and regulates extracellular matrix turnover, thereby playing a crucial role in tissue remodeling in the gut. In this review we describe the mechanisms by which abnormal TGF-β signaling impairs intestinal immune tolerance and tissue repair, thus predisposing to the onset of immune-mediated bowel disorders, such as inflammatory bowel disease and celiac disease. Additionally, we will discuss potential therapeutic strategies aiming at restoring physiologic TGF-β signaling in chronic intestinal diseases.

Cellular and molecular mechanisms of intestinal fibrosis

Fibrosis is a chronic and progressive process characterized by an excessive accumulation of extracellular matrix (ECM) leading to stiffening and/or scarring of the involved tissue. Intestinal fibrosis may develop in several different enteropathies, including inflammatory bowel disease. It develops through complex cell, extracellular matrix, cytokine and growth factor interactions. Distinct cell types are involved in intestinal fibrosis, such as resident mesenchymal cells (fibroblasts, myofibroblasts and smooth muscle cells) but also ECM-producing cells derived from epithelial and endothelial cells (through a process termed epithelial- and endothelial-mesenchymal transition), stellate cells, pericytes, local or bone marrow-derived stem cells. The most important soluble factors that regulate the activation of these cells include cytokines, chemokines, growth factors, components of the renin-angiotensin system, angiogenic factors, peroxisome proliferator-activated receptors, mammalian target of rapamycin, and products of oxidative stress. It soon becomes clear that although inflammation is responsible for triggering the onset of the fibrotic process, it only plays a minor role in the progression of this condition, as fibrosis may advance in a self-perpetuating fashion. Definition of the cellular and molecular mechanisms involved in intestinal fibrosis may provide the key to developing new therapeutic approaches.