Transforming growth factor-beta type 1 receptor (ALK5) and Smad proteins mediate TIMP-1 and collagen synthesis in experimental intestinal fibrosis

Transforming growth factor-β receptors: versatile mechanisms of ligand activation

Transforming growth factor-β (TGF-β) signaling is initiated by activation of transmembrane TGF-β receptors (TGFBR), which deploys Smad2/3 transcription factors to control cellular responses. Failure or dysregulation in the TGF-β signaling pathways leads to pathological conditions. TGF-β signaling is regulated at different levels along the pathways and begins with the liberation of TGF-β ligand from its latent form. The mechanisms of TGFBR activation display selectivity to cell types, agonists, and TGF-β isoforms, enabling precise control of TGF-β signals. In addition, the cell surface compartments used to release active TGF-β are surprisingly vibrant, using thrombospondins, integrins, matrix metalloproteinases and reactive oxygen species. The scope of TGFBR activation is further unfolded with the discovery of TGFBR activation initiated by other signaling pathways. The unique combination of mechanisms works in series to trigger TGFBR activation, which can be explored as therapeutic targets. This comprehensive review provides valuable insights into the diverse mechanisms underpinning TGFBR activation, shedding light on potential avenues for therapeutic exploration.

Design, synthesis and evaluation of a pyrazolo[3,4-d]pyrimidine derivative as a novel and potent TGFβ1R1 inhibitor

The transforming growth factor β1 (TGFβ1)/SMAD signaling pathway regulates many vital physiological processes. The development of potent inhibitors targeting activin receptor-like kinase 5 (ALK5) would provide potential treatment reagents for various diseases. A significant number of ALK5 inhibitors have been discovered, and they are currently undergoing clinical evaluation at various stages. However, the clinical demands were far from being met. In this study, we utilized an alternative conformation-similarity-based virtual screening (CSVS) combined with a fragment-based drug designing (FBDD) strategy to efficiently discover a potent and active hit with a novel chemical scaffold. After structural optimization in the principle of group replacement, compound 57 was identified as the most promising ALK5 inhibitor. Compound 57 demonstrated significant inhibitory effects against the TGF-β1/SMAD signaling pathway. It could markedly attenuate the production of extracellular matrix (ECM) and deposition of collagen. Also, the lead compound showed adequate pharmacokinetic (PK) properties and good in vivo tolerance. Moreover, treatment with compound 57 in two different xerograph models showed significant inhibitory effects on the growth of pancreatic cancer cells. These results suggested that lead compound 57 refers as a promising ALK5 inhibitor both in vitro and in vivo, which merits further validation.

A modest proposal: targeting αv integrin-mediated activation of latent TGFbeta as a novel therapeutic approach to treat scleroderma fibrosis

INTRODUCTION

The potent profibrotic cytokine transforming growth factor-β (TGF-β) has been associated with the onset and progression of the fibrosis seen in the autoimmune connective tissue disease scleroderma (systemic sclerosis, SSc).

AREA COVERED

This review explores the data supporting the notion that TGF-β contributes to SSc fibrosis and examines why initiating clinical trials in SSc aimed at targeting integrin-mediated latent TGF-β activation is timely.

EXPERT OPINION

Targeting TGF-β directly has not been proven to be clinically effective in this disease. Conversely, targeting matrix stiffness, which perpetuates fibrosis, may have more promise. Intriguingly, targeting integrin-mediated activation of latent TGF-β, which bridges these concepts, may have therapeutic value.

Downregulation of Heat Shock Protein 72 Contributes to Fibrostenosis in Crohn's Disease

Background/Aims

Crohn's disease (CD) with recurrent inflammation can cause intestinal fibrostenosis due to dysregulated deposition of extracellular matrix. However, little is known about the pathogenesis of fibrostenosis. Here, we performed a differential proteomic analysis between normal, inflamed, and fibrostenotic specimens of patients with CD and investigated the roles of the candidate proteins in myofibroblast activation and fibrosis.

Methods

We performed two-dimensional difference gel electrophoresis and identified candidate proteins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and orbitrap liquid chromatography-mass spectrometry. We also verified the levels of candidate proteins in clinical specimens and examined their effects on 18Co myofibroblasts and Caco-2 intestinal epithelial cells.

Results

We identified five of 30 proteins (HSP72, HSPA5, KRT8, PEPCK-M, and FABP6) differentially expressed in fibrostenotic CD. Among these proteins, the knockdown of heat shock protein 72 (HSP72) promoted the activation and wound healing of myofibroblasts. Moreover, knockdown of HSP72 induced the epithelial-mesenchymal transition of intestinal epithelial cells by reducing E-cadherin and inducing fibronectin and α-smooth muscle actin, which contribute to fibrosis.

Conclusions

HSP72 is an important mediator that regulates myofibroblasts and epithelial-mesenchymal transition in fibrosis of CD, suggesting that HSP72 can serve as a target for antifibrotic therapy.

An Analysis of the Content of Metalloproteinases in the Intestinal Wall of Patients with Crohn's Disease

One of the inflammatory bowel diseases is Crohn's disease. Although this term has been used in the medical community since 1932, a significant increase in the number of publications occurs at the end of the 20th century and the beginning of the 21st century. Crohn's disease is a disease that cannot be fully cured. In many cases, it is chronic, i.e., recurrent. All preventive and therapeutic measures taken by doctors are aimed at inhibiting the development of the disease and minimizing the occurrence of any potential "side effects" resulting from the developing disease. One of the diagnostic methods is the qualitative and quantitative determination of metalloproteinases in inflammatory tissues and in the blood. The aim of the study was the quantitative and qualitative determination of metalloproteinases in inflammatory bowel tissues in patients diagnosed with Crohn's disease. The in vitro study was performed on surgical tissues from patients diagnosed with Crohn's disease. The results show that in inflammatory tissues the concentration of metalloproteinases -3, -7, -8, -9 was higher compared to tissues taken from the resection margin without signs of inflammation, defined as healthy. The experiment confirmed that the biochemical test, which is the determination of metalloproteinases in tissues, is a useful diagnostic tool to differentiate inflammatory from non-inflammatory tissues.

Soluble dipeptidyl peptidase-4 induces epithelial-mesenchymal transition through tumor growth factor-β receptor

BACKGROUND

Kidney fibrosis is the final manifestation of chronic kidney disease, a condition mainly caused by diabetic nephropathy. Persistent tissue damage leads to chronic inflammation and excessive deposition of extracellular matrix (ECM) proteins. Epithelial-mesenchymal transition (EMT) is involved in a variety of tissue fibrosis and is a process during which epithelial cells transform into mesenchymal-like cells and lose their epithelial functionality and characteristics Dipeptidyl peptidase-4 (DPP4) is widely expressed in tissues, especially those of the kidney and small intestine. DPP4 exists in two forms: a plasma membrane-bound and a soluble form. Serum-soluble DPP4 (sDPP4) levels are altered in many pathophysiological conditions. Elevated circulating sDPP4 is correlated with metabolic syndrome. Because the role of sDPP4 in EMT remains unclear, we examined the effect of sDPP4 on renal epithelial cells.

METHODS

The influences of sDPP4 on renal epithelial cells were demonstrated by measuring the expression of EMT markers and ECM proteins.

RESULTS

sDPP4 upregulated the EMT markers ACTA2 and COL1A1 and increased total collagen content. sDPP4 activated SMAD signaling in renal epithelial cells. Using genetic and pharmacological methods to target TGFBR, we observed that sDPP4 activated SMAD signaling through TGFBR in epithelial cells, whereas genetic ablation and treatment with TGFBR antagonist prevented SMAD signaling and EMT. Linagliptin, a clinically available DPP4 inhibitor, abrogated sDPP4-induced EMT.

CONCLUSIONS

This study indicated that sDPP4/TGFBR/SMAD axis leads to EMT in renal epithelial cells. Elevated circulating sDPP4 levels may contribute to mediators that induce renal fibrosis.

Dual role of enhancer of zeste homolog 2 in the regulation of ultraviolet radiation-induced matrix metalloproteinase-1 and type I procollagen expression in human dermal fibroblasts

Abnormalities in the extracellular matrix (ECM) caused by ultraviolet (UV) radiation are mediated by epigenetic mechanisms. Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that is implicated in inflammation, immune regulation, and senescence. However, its role in controlling UV-induced ECM alterations in the skin remains elusive. Here, we investigated the role of EZH2 in UV-induced expression of matrix metalloproteinase (MMP)-1 and type I procollagen. We found that UV induced EZH2 expression in human skin in vivo and in human dermal fibroblasts (HDFs). EZH2 knockdown reduced the expression and promoter activity of MMP-1 and increased those of type I procollagen, whereas EZH2 overexpression had the opposite effects. Mechanistically, EZH2 increased NF-κB activity, and p65 and p50 expression and promoter activity. Intriguingly, chromatin immunoprecipitation assays revealed that the EZH2/p65/p50 complex was recruited and bound to the MMP-1 promoter after UV irradiation, independent of its histone methyltransferase activity. In contrast, EZH2-induced DNA methyltransferase 1 (DNMT1) formed a complex with EZH2 and enhanced the enrichment of H3K27me3 on the COL1A2 promoter following UV irradiation. These findings indicate that EZH2 plays a dual role in regulating MMP-1 and type I procollagen expression and improve our understanding of how this epigenetic mechanism contributes to UV-induced skin responses and photoaging. This study shows that inhibiting EZH2 is a potential anti-aging strategy for preventing UV-induced skin aging by reducing MMP-1 expression and inducing type I procollagen expression.

The role of transforming growth factor-β2 in cigarette smoke-induced lung inflammation and injury

AIMS

Transforming growth factor-β2 (TGF-β2) plays an important role in pleiotropic functions and has been reported to be involved in the pathogenesis of chronic obstructive lung disease. The role of TGF-β2 in regulating cigarette smoke (CS)-induced lung inflammation and injury has not been investigated, and its underlying mechanism remains unclear.

MAIN METHODS

Primary bronchial epithelial cells (PBECs) were treated with cigarette smoke extract (CSE), and the signaling pathway of TGF-β2 regulating lung inflammation was investigated. Mice were exposed to CS and treated with TGF-β2 i.p. or bovine whey protein extract containing TGF-β2 p.o., and the role of TGF-β2 in alleviating lung inflammation/injury was studied.

KEY FINDINGS

In vitro, we demonstrated that TGF-β2 attenuated CSE-induced IL-8 production from PBECs through the TGF-β receptor I (TGF-βRI), Smad3, and mitogen-activated protein kinase signaling pathways. Selective TGF-βRI inhibitor (LY364947) and antagonist of Smad3 (SIS3) abolished the effect of TGF-β2 on alleviating CSE-induced IL-8 production. In vivo, CS exposure for 4 weeks in mice increased the levels of total protein, inflammatory cell counts, and monocyte chemoattractant protein-1 in bronchoalveolar fluid and induced lung inflammation/injury, as revealed by immunohistochemistry. Administration of TGF-β2 through intraperitoneal injection or oral feeding with bovine whey protein extract containing TGF-β2 significantly reduced CS-induced lung inflammation and injury.

SIGNIFICANCE

We concluded that TGF-β2 reduced CSE-induced IL-8 production through the Smad3 signaling pathway in PBECs and alleviated lung inflammation/injury in CS-exposed mice. The anti-inflammatory effect of TGF-β2 on CS-induced lung inflammation in humans deserves further clinical study.

Potential of the TRPM7 channel as a novel therapeutic target for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an intractable vascular disease characterized by a progressive increase in pulmonary vascular resistance caused by pulmonary vascular remodeling, which ultimately leads to right-sided heart failure. PAH remains incurable, despite the development of PAH-targeted therapeutics centered on pulmonary artery relaxants. It is necessary to identify the target molecules that contribute to pulmonary artery remodeling. Transient receptor potential (TRP) channels have been suggested to modulate pulmonary artery remodeling. Our study focused on the transient receptor potential ion channel subfamily M, member 7, or the TRPM7 channel, which modulates endothelial-to-mesenchymal transition and smooth muscle proliferation in the pulmonary artery. In this review, we summarize the role and expression profile of TRPM7 channels in PAH progression and discuss TRPM7 channels as possible therapeutic targets. In addition, we discuss the therapeutic effect of a Chinese herbal medicine, Ophiocordyceps sinensis (OCS), on PAH progression, which partly involves TRPM7 inhibition.

Therapeutic Potential of the Combination of Pentoxifylline and Vitamin-E in Inflammatory Bowel Disease: Inhibition of Intestinal Fibrosis

Background: Although intestinal fibrosis is a consequence of recurrent inflammation in Inflammatory bowel disease (IBD), alleviating inflammation alone does not prevent the progression of fibrosis, suggesting that the development of direct anti-fibrotic agents is necessary. This study aimed to evaluate the anti-fibrotic properties of combination treatment with pentoxifylline (PTX) and vitamin E (Vit-E) on human primary intestinal myofibroblasts (HIMFs) and the therapeutic potential of the combination therapy in murine models of IBD. Methods: HIMFs were pretreated with PTX, Vit-E, or both, and incubated with TGF-β1. We performed Western blot, qPCR, collagen staining, and immunofluorescence to estimate the anti-fibrotic effects of PTX and Vit-E. The cytotoxicity of these was investigated through MTT assay. To induce murine models of IBD for in vivo study, C57BL/6 mice were treated with repeated cycles of dextran sulfate sodium (DSS), developing chronic colitis. We examined whether the combined PTX and Vit-E treatment would effectively ameliorate colonic fibrosis in vivo. Results: We found that the co-treatment with PTX and Vit-E suppressed TGF-β1-induced expression of fibrogenic markers, with decreased expression of pERK, pSmad2, and pJNK, more than either treatment alone in HIMFs. Neither PTX nor Vit-E showed any significant cytotoxicity in given concentrations. Consistently with the in vitro results, the co-administration with PTX and Vit-E effectively attenuated colonic fibrosis with recovery from thickening and shortening of colon in murine models of IBD. Conclusions: These findings demonstrated that the combination of PTX and Vit-E exhibits significant anti-fibrotic effects in both HIMFs and in vivo IBD models, providing a promising therapy for IBD.

Synthesis and preclinical evaluation of [11C]LR111 and [18F]EW-7197 as PET tracers of the activin-receptor like kinase-5

The transforming growth factor β (TGFβ) pathway plays a complex role in cancer biology, being involved in both tumour suppression as well as promotion. Overactive TGFβ signalling has been linked to multiple diseases, including cancer, pulmonary arterial hypertension, and fibrosis. One of the key meditators within this pathway is the TGFβ type I receptor, also termed activin receptor-like kinase 5 (ALK5). ALK5 expression level is a key determinant of TGFβ signalling intensity and duration, and perturbation has been linked to diseases. A validated ALK5 positron emission tomography (PET) tracer creates an opportunity, therefore, to study its role in human diseases. To develop ALK5 PET tracers, two small molecule ALK5 kinase inhibitors were selected as lead compounds, which were labelled with carbon-11 and fluorine-18, respectively. [¹¹C]LR111 was synthesized with a yield of 17 ± 6%, a molar activity of 126 ± 79 GBq·μmol^-1 and a purity of >95% (n = 44). [¹⁸F]EW-7197 was synthesized with a yield of 10 ± 5%, a molar activity of 183 ± 126 GBq·μmol^-1 and a purity of >95% (n = 11). Metabolic stability was evaluated in vivo in mice, showing 39 ± 2% of intact [¹¹C]LR111 and 21 ± 2% of intact [¹⁸F]EW-7197 in blood plasma at 45 min p.i. In vitro binding experiments were conducted in breast cancer MDA-MB-231 and lung cancer A431 cell lines. In addition, both tracers were used for PET imaging in MDA-MB-231 xenograft models. Selective uptake of [¹⁸F]EW-7197 and [¹¹C]LR111 was observed in MDA-MB-231 cells, in the MDA-MB-231 tumour xenografts in vivo and in the autoradiograms. As [¹¹C]LR111 and [¹⁸F]EW-7197 showed selectivity of binding to ALK5 in vivo and in vitro. Both tracers are thereby valuable tools for the detection of ALK5 activity.

Contribution of the Gut Microbiota to Intestinal Fibrosis in Crohn's Disease

In Crohn's disease (CD), intestinal fibrosis is a critical determinant of a patient's prognosis. Although inflammation may be a prerequisite for the initiation of intestinal fibrosis, research shows that the progression or continuation of intestinal fibrosis can occur independently of inflammation. Thus, once initiated, intestinal fibrosis may persist even if medical treatment controls inflammation. Clearly, an understanding of the pathophysiological mechanisms of intestinal fibrosis is required to diminish its occurrence. Accumulating evidence suggests that the gut microbiota contributes to the pathogenesis of intestinal fibrosis. For example, the presence of antibodies against gut microbes can predict which CD patients will have intestinal complications. In addition, microbial ligands can activate intestinal fibroblasts, thereby inducing the production of extracellular matrix. Moreover, in various animal models, bacterial infection can lead to the development of intestinal fibrosis. In this review, we summarize the current knowledge of the link between intestinal fibrosis in CD and the gut microbiota. We highlight basic science and clinical evidence that the gut microbiota can be causative for intestinal fibrosis in CD and provide valuable information about the animal models used to investigate intestinal 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.

TGF-β as a driver of fibrosis: physiological roles and therapeutic opportunities

Many chronic diseases are marked by fibrosis, which is defined by an abundance of activated fibroblasts and excessive deposition of extracellular matrix, resulting in loss of normal function of the affected organs. The initiation and progression of fibrosis are elaborated by pro-fibrotic cytokines, the most critical of which is transforming growth factor-β1 (TGF-β1). This review focuses on the fibrogenic roles of increased TGF-β activities and underlying signaling mechanisms in the activated fibroblast population and other cell types that contribute to progression of fibrosis. Insight into these roles and mechanisms of TGF-β as a universal driver of fibrosis has stimulated the development of therapeutic interventions to attenuate fibrosis progression, based on interference with TGF-β signaling. Their promise in preclinical and clinical settings will be discussed. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Restraint Stress in Hypertensive Rats Activates the Intestinal Macrophages and Reduces Intestinal Barrier Accompanied by Intestinal Flora Dysbiosis

Purpose

Hypertension (HTN) is a major risk factor for cardiovascular disease. In recent years, there were numerous studies on the function of stress in HTN. However, the gut dysbiosis linked to hypertension in animal models under stress is still incompletely understood. Purpose of this study is to use multiple determination method to determine the juvenile stage intestinal bacteria, cytokines and changes in hormone levels.

Methods

Four groups of juvenile male spontaneously hypertensive rats (SHRs) and age-matched male Wistar-Kyoto (WKY) rats were randomly selected as control and experimental groups. Rats in the two stress groups were exposed to restraint stress for 3 hours per day for 7 consecutive days. In one day three times in the method of non-invasive type tail-cuff monitoring blood pressure. The detailed mechanism was illuminated based on the intestinal change using immunohistochemical and immunofluorescence staining and the stress-related hormone and inflammation factors were analyzed via ELISA method. The integrity of the epithelial barrier was assessed using FITC/HRP and the expression levels of proteins associated with the tight junction was detected by Western blot. The alteration of stress-related intestinal flora from ileocecal junction and distal colon were also analyzed using its 16S rDNA sequencing.

Results

The results indicate that acute stress rapidly increases mean arterial pressure which is positive correlation to hormone concentration, especially in SHR-stress group. Meanwhile, stress promoted the enhancement of epithelial permeability accompanied with a reduced expression of the tight junction-related protein and the macrophages (Mφ) aggregation to the lamina propria. There were remarkable significant increase of stress-related hormones and pro-inflammatory factor interleukin (IL)-6 along with a decrease in the diversity of intestinal flora and an imbalance in the F/B ratio.

Conclusion

Our results reveal that stress accompanied with HTN could significantly disrupt the domino effect between intestinal flora and homeostasis.

Adherent invasive Escherichia coli (AIEC) strain LF82, but not Candida albicans, plays a profibrogenic role in the intestine

BACKGROUND

Intestinal fibrosis is a frequent complication of Crohn's disease. However, the factors that cause chronicity and promote fibrogenesis are not yet understood.

AIMS

In the present study, we evaluated the profibrotic effects of adherent-invasive Escherichia coli (AIEC) LF82 strain and Candida albicans in the gut.

METHODS

Colonic fibrosis was induced in C57BL/6 mice by administration of three cycles of 2.5% (w/v) dextran sulfate sodium (DSS) for 5 weeks. LF82 and C. albicans were administered orally once at the start of each week or each cycle, respectively. Expression of markers of myofibroblast activation was determined in TGF-β1-stimulated human intestinal epithelial cells (IECs).

RESULTS

LF82 administration exacerbated fibrosis in DSS-treated mice, revealed by increased colonic collagen deposition and expression of the profibrotic genes Col1a1, Col3a1, Fn1 and Vim. This was accompanied by enhanced gene expression of proinflammatory cytokines and chemokines, as well as more recruited inflammatory cells into the intestine. LF82 also potentiated TGF-β1-stimulated epithelial-mesenchymal transition and myofibroblast activation in IECs, by further inducing gene expression of the main mesenchymal cell markers FN1 and VIM and downregulating the IEC marker OCLN. Proinflammatory cytokines were overexpressed with LF82 in TGF-β1-stimulated IECs. Conversely, C. albicans did not affect intestinal fibrosis progression in DSS-treated mice or myofibroblast activation in TGF-β1-stimulated IECs.

CONCLUSIONS

These results demonstrate that AIEC strain LF82, but not C. albicans, may play a major profibrogenic role in the gut.

The Epithelial-to-Mesenchymal Transition as a Possible Therapeutic Target in Fibrotic Disorders

Fibrosis is a chronic and progressive disorder characterized by excessive deposition of extracellular matrix, which leads to scarring and loss of function of the affected organ or tissue. Indeed, the fibrotic process affects a variety of organs and tissues, with specific molecular background. However, two common hallmarks are shared: the crucial role of the transforming growth factor-beta (TGF-β) and the involvement of the inflammation process, that is essential for initiating the fibrotic degeneration. TGF-β in particular but also other cytokines regulate the most common molecular mechanism at the basis of fibrosis, the Epithelial-to-Mesenchymal Transition (EMT). EMT has been extensively studied, but not yet fully explored as a possible therapeutic target for fibrosis. A deeper understanding of the crosstalk between fibrosis and EMT may represent an opportunity for the development of a broadly effective anti-fibrotic therapy. Here we report the evidences of the relationship between EMT and multi-organ fibrosis, and the possible therapeutic approaches that may be developed by exploiting this relationship.

Chronic inflammation and other changes are significant components of clinically fibrotic strictures in Crohn's disease: a histological study of resected strictures clinically characterized as noninflamed

BACKGROUND

Strictures related to Crohn's disease due to fibrosis are a result of an exaggerated tissue remodelling response to inflammation, characterized by accumulation of collagen-rich extracellular matrix produced by mesenchymal cells.

OBJECTIVES

The objective of this study was to characterize histological changes seen in resected 'fibrotic' strictures to better understand individual components of intestinal stenosis.

METHODS

We identified patients undergoing surgery for ileal Crohn's disease secondary to symptomatic stricturing disease (Montreal B2) using the histopathology database at Queen Elizabeth Hospital in Birmingham, UK, between 2012 and 2017. Phenotypic data were recorded and resection specimens reviewed. Two independent pathologists applied the semiquantitative scoring system previously developed by us to the microscopic images. Data were analyzed using the possible maximum total score (%PMTS).

RESULTS

Forty-eight patients (M = 25) were included. with median disease duration of 7 years (range 0.25-39 years); nearly two-thirds had ileocolonic distribution (L3). In this cohort, despite presurgery diagnosis of noninflamed fibrosis, chronic inflammation was noted to be a prominent component of all strictures. The histological scoring showed presence of several other prominent findings such as muscular hyperplasia and volume expansion.There was statistically significant positive correlation between chronic inflammation and fibrosis and muscular hyperplasia.

CONCLUSION

The histological features of Crohn's disease-related strictures show multiple changes in multiple layers and not simply fibrosis. In our cohort, despite the observation prior to surgery that strictures were clinically considered fibrotic, the finding of chronic inflammation as a dominant component at a histological level in the resection is important. The findings might suggest that one of the main drivers of progressive fibrosis is the inflammatory component, which probably is never fully resolved.

Implications of immune-inflammatory responses in smooth muscle dysfunction and disease

In the past few decades, solid evidence has been accumulated for the pivotal significance of immunoinflammatory processes in the initiation, progression, and exacerbation of many diseases and disorders. This groundbreaking view came from original works by Ross who first described that excessive inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall is essential for the pathogenesis of atherosclerosis (Ross, Nature 1993; 362(6423): 801–9). It is now widely recognized that both innate and adaptive immune reactions are avidly involved in the inflammation-related remodeling of many tissues and organs. When this state persists, irreversible fibrogenic changes would occur often culminating in fatal insufficiencies of many vital parenchymal organs such as liver, lung, heart, kidney and intestines. Thus, inflammatory diseases are becoming the common life-threatening risk for and urgent concern about the public health in developed countries (Wynn et al., Nature Medicine 2012; 18(7): 1028–40). Considering this timeliness, we organized a special symposium entitled “Implications of immune/inflammatory responses in smooth muscle dysfunction and disease” in the 58th annual meeting of the Japan Society of Smooth Muscle Research. This symposium report will provide detailed synopses of topics presented in this symposium; (1) the role of inflammasome in atherosclerosis and abdominal aortic aneurysms by Fumitake Usui-Kawanishi and Masafumi Takahashi; (2) Mechanisms underlying the pathogenesis of hyper-contractility of bronchial smooth muscle in allergic asthma by Hiroyasu Sakai, Wataru Suto, Yuki Kai and Yoshihiko Chiba; (3) Vascular remodeling in pulmonary arterial hypertension by Keizo Hiraishi, Lin Hai Kurahara and Ryuji Inoue.

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.

Study on the relationship between hepatic fibrosis and epithelial-mesenchymal transition in intrahepatic cells

Hepatic fibrosis is a pathophysiological process, which causes excessive extracellular matrix (ECM) deposition resulting from persistent liver damage. Myofibroblasts are the core cells that produce ECM. It is known that epithelial-mesenchymal transition (EMT) is not a simple transition of cells from the epithelial to mesenchymal state. Instead, it is a process, in which epithelial cells temporarily lose cell polarity, transform into interstitial cell-like morphology, and acquire migration ability. Hepatocytes, hepatic stellate cells, and bile duct cells are the types of intrahepatic cells found in the liver. They can be transformed into myofibroblasts via EMT and play important roles in the development of hepatic fibrosis through a maze of regulations involving various pathways. The aim of the present study is to explore the relationship between the relevant regulatory factors and the EMT signaling pathways in the various intrahepatic cells.

Fibrostenotic strictures in Crohn's disease

The use of biologic agents including anti-tumor necrosis factor monoclonal antibodies followed by anti-integrins and anti-interleukins has drastically changed the treatment paradigm of Crohn’s disease (CD) by improving clinical symptoms and mucosal healing. However, up to 70% of CD patients still eventually undergo surgery mainly due to fibrostenotic strictures. There are no specific anti-fibrotic drugs yet. This review comprehensively addresses the mechanism, prediction, diagnosis and treatment of the fibrostenotic strictures in CD. We also introduce promising anti-fibrotic agents which may be available in the near future and summarize challenges in developing novel therapies to treat fibrostenotic strictures in CD.

Transforming growth factor-β in tissue fibrosis

TGF-β is extensively implicated in the pathogenesis of fibrosis. In fibrotic lesions, spatially restricted generation of bioactive TGF-β from latent stores requires the cooperation of proteases, integrins, and specialized extracellular matrix molecules. Although fibroblasts are major targets of TGF-β, some fibrogenic actions may reflect activation of other cell types, including macrophages, epithelial cells, and vascular cells. TGF-β–driven fibrosis is mediated through Smad-dependent or non-Smad pathways and is modulated by coreceptors and by interacting networks. This review discusses the role of TGF-β in fibrosis, highlighting mechanisms of TGF-β activation and signaling, the cellular targets of TGF-β actions, and the challenges of therapeutic translation.

Effects of suppressing Smads expression on wound healing in Hyriopsis cumingii

As a specific pearl mussel in China, Hyriopsis cumingii has enormous economic value. However, the organism damage caused by pearl insertion is immeasurable. TGF-β/Smad signal transduction pathways are involved in all phases of wound healing. We have previously reported on two cytoplasmic signal transduction factors, Smad3 and Smad5 in mussel H. cumingii (named HcSmads), suggesting their involvements in wound healing. Here, Smad4 was cloned and described. The full length cDNA of HcSmad4 was 2543 bp encoded 515 amino acids. Deduced HcSmad4 protein possessed conserved MH1 and MH2 domains, nuclear location signals (NLS), nuclear exput signals (NES) and Smad activation domain (SAD). Transcripts of Smad3, 4 and 5 were constitutively expressed in all detected tissues, at highest levels in muscles. Furthermore, HcSmad4 mRNA levels were significantly increased at incision site post wounding, and expression of downstream target genes of Smad4, such as HcMMP1, HcMMP19, HcTIMP1 and HcTIMP2 were upregulated to a certain extent. Whatever knocked down HcSmad3/4 or treated by specific inhibitors of Smad 3 (SIS3), expression levels of these genes displayed a significantly downregulated tendency compared with the wound group. In addition, histological evaluation suggested that Smad3 knockdown or SIS3 treatment was accelerated wound healing, and then Smad4 knockdown delayed the process of wound healing in mussels. These data implicate that Smad3/4 play an important role in tissue repair in mollusks.

AMD3100 Attenuates Post-Traumatic Osteoarthritis by Maintaining Transforming Growth Factor-β1-Induced Expression of Tissue Inhibitor of Metalloproteinase-3 via the Phosphatidylinositol 3-Kinase/Akt Pathway

AMD3100 is a small-molecule inhibitor of the C-X-C motif chemokine ligand 12/C-X-C chemokine receptor type 4 (CXCL12/CXCR4) axis, while its role in aggrecan metabolism is unclear. We hypothesized that the AMD3100 modulates the transforming growth factor-β1 (TGF-β1)-induced expression of tissue inhibitor of metalloproteinase-3 (TIMP-3) in chondrocytes. We evaluated expression of CXCL12/CXCR4 and TIMP-3 in the knee joints of rats with and without osteoarthritis (OA) by immunohistochemistry, immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay (ELISA). The rats were divided into sham control, destabilization of the medial meniscus/AMD3100-treated (DMM/AMD3100-treated), and DMM/phosphate-buffered saline (PBS)-treated groups. After 6 weeks, the rats were euthanized and subjected to histological and immunohistochemical analyses. Also, interleukin (IL)-1-pretreated primary chondrocytes were cultured in the presence of empty control (−, −), CXCL12a (+,−), CXCL12a + small interfering RNA (siRNA) CXCR4 (+,+), or CXCL12a + siNC (+NC), and the expression levels of target markers were evaluated by Western blotting and real-time reverse transcription PCR (RT-PCR). The CXCL12/CXCR4 levels were higher, and the expression of TIMP-3 was lower, in the OA rats compared to the healthy control rats. The rats in the DMM/AMD3100-treated group revealed a markedly decreased immunological response and mild pathology. Treatment with CXCL12a increased expression of aggrecan and disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5) and suppressed that of TIMP-3 in IL-1-pretreated primary chondrocytes. TGF-β1 increased expression of TIMP-3, and this increase was reversed by CXCL12a via the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Moreover, these effects were inhibited by the CXCR4 antagonist AMD3100 and the PI3K inhibitor LY303511. In conclusion, inhibition of the CXCL12a/CXCR4 signaling axis maintained TIMP-3 expression via the PI3K/Akt pathway. Our findings provide insight into the mechanism by which AMD3100 prevents OA.

Umbilical cord/placenta-derived mesenchymal stem cells inhibit fibrogenic activation in human intestinal myofibroblasts via inhibition of myocardin-related transcription factor A

Background

The lack of anti-fibrotic agents targeting intestinal fibrosis is a large unmet need in inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis. Previous studies have found that perinatal tissue (umbilical cord, UC; placenta, PL)-derived mesenchymal stem cells (MSCs) reduce fibrosis in several organs. However, their effects on human intestinal fibrosis are poorly understood. This study investigated the anti-fibrogenic properties and mechanisms of MSCs derived from UC and PL (UC/PL-MSCs) on human primary intestinal myofibroblasts (HIMFs).

Methods

The HIMFs were treated with TGF-β1 and co-cultured with UC/PL-MSCs. We used a small molecular inhibitor CCG-100602 to examine whether serum response factor (SRF) and its transcriptional cofactor myocardin-related transcription factor A (MRTF-A) are involved in TGF-β1-induced fibrogenic activation in HIMFs. The anti-fibrogenic mechanism of UC/PL-MSCs on HIMFs was analyzed by detecting the expression of RhoA, MRTF-A, and SRF in HIMFs.

Results

UC/PL-MSCs reduced TGF-β1-induced procollagen1A1, fibronectin, and α-smooth muscle actin expression in HIMFs. This anti-fibrogenic effect was more apparent in the UC-MSCs. TGF-β1 stimulation increased the expressions of RhoA, MRTF-A, and SRF in the HIMFs. TGF-β1 induced the synthesis of procollagen1A1, fibronectin, and α-smooth muscle actin through a MRTF-A/SRF-dependent mechanism. Co-culture with the UC/PL-MSCs downregulated fibrogenesis by inhibition of RhoA, MRTF-A, and SRF expression.

Conclusions

UC/PL-MSCs suppress TGF-β1-induced fibrogenic activation in HIMFs by blocking the Rho/MRTF/SRF pathway and could be considered as a novel candidate for stem cell-based therapy of intestinal fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1385-8) contains supplementary material, which is available to authorized users.

Role of Epithelial-to-Mesenchymal Transition in Inflammatory Bowel Disease

Intestinal fibrosis is an inevitable complication in patients with inflammatory bowel disease [IBD], occurring in its two major clinical manifestations: ulcerative colitis and Crohn's disease. Fibrosis represents the final outcome of the host reaction to persistent inflammation, which triggers a prolonged wound healing response resulting in the excessive deposition of extracellular matrix, eventually leading to intestinal dysfunction. The process of epithelial-to-mesenchymal transition [EMT] represents an embryonic program relaunched during wound healing, fibrosis and cancer. Here we discuss the initial observations and the most recent findings highlighting the role of EMT in IBD-associated intestinal fibrosis and fistulae formation. In addition, we briefly review knowledge on the cognate process of endothelial-to-mesenchymal transition [EndMT]. Understanding EMT functionality and the molecular mechanisms underlying the activation of this mesenchymal programme will permit designing new therapeutic strategies to halt the fibrogenic response in the intestine.

Protective Effect of Anthocyanin on Paraquat-Induced Apoptosis and Epithelial-Mesenchymal Transition in Alveolar Type II Cells

BACKGROUND Paraquat (PQ) can over-accumulate in alveolar epithelial cells. Anthocyanin (An) can exert anti-oxidative properties. The role of An in PQ-induced toxicity is unclear, so we aimed to explore whether An could inhibit epithelial mesenchymal transition (EMT) induced by PQ in alveolar cells. MATERIAL AND METHODS lveolar epithelial cells were treated with PQ and An with concentration gradient for 12, 24, and 48 h. The cell viability, ROS level, and apoptosis rate were determined using the Cell Counting Kit-8 (CCK-8) and flow cytometry, respectively. The lactate dehydrogenase (LDH) leakage, methane dicarboxylic aldehyde (MDA) level, glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities were determined by spectrophotometric method. The mRNA and protein expressions were detected using quantitative real-time PCR (qPCR) and Western blot, respectively. RESULTS An reduced the PQ-induced apoptosis in a dose-dependent manner. Moreover, An reduced the ratio of Bax/Bcl-2 to ROS level. We found that An suppressed the activity of LDH and MDA and improved SOD and GPX levels. Additionally, the level of PQ-induced E-cadherin was decreased by An while the expressions of vimentin, α-smooth muscle actin (α-SMA), and collagens type I (col-I) were increased. Furthermore, An inhibited the levels of transforming growth factor β1 (TGF-β1) and activin receptor-like kinase 5 (ALK5) and reduced the phosphorylation of smad2. CONCLUSIONS Our study shows newly discovered effects of anthocyanidins on EMT and supports their chemopreventive effects in paraquat-induced apoptosis in alveolar type II cells.

Daikenchuto (Da-Jian-Zhong-Tang) ameliorates intestinal fibrosis by activating myofibroblast transient receptor potential ankyrin 1 channel

AIM

To investigate the anti-fibrotic effects of the traditional oriental herbal medicine Daikenchuto (DKT) associated with transient receptor potential ankyrin 1 (TRPA1) channels in intestinal myofibroblasts.

METHODS

Inflammatory and fibrotic changes were detected in a 2,4,6-trinitrobenzenesulfonic acid (TNBS) chronic colitis model of wild-type and TRPA1-knockout (TRPA1-KO) mice via pathological staining and immunoblotting analysis. Ca²⁺ imaging experiments examined the effects of DKT and its components/ingredients on intestinal myofibroblast (InMyoFib) cell TRPA1 channel function. Pro-fibrotic factors and transforming growth factor (TGF)-β1-associated signaling were tested in an InMyoFib cell line by qPCR and immunoblotting experiments. Samples from non-stenotic and stenotic regions of the intestines of patients with Crohn’s disease (CD) were used for pathological analysis.

RESULTS

Chronic treatment with TNBS caused more severe inflammation and fibrotic changes in TRPA1-KO than in wild-type mice. A one-week enema administration of DKT reduced fibrotic lesions in wild-type but not in TRPA1-KO mice. The active ingredients of DKT, i.e., hydroxy α-sanshool and 6-shogaol, induced Ca²⁺ influxes in InMyoFib, and this was antagonized by co-treatment with a selective TRPA1 channel blocker, HC-030031. DKT counteracted TGF-β1-induced expression of Type I collagen and α-smooth muscle actin (α-SMA), which were accompanied by a reduction in the phosphorylation of Smad-2 and p38-mitogen-activated protein kinase (p38-MAPK) and the expression of myocardin. Importantly, 24-h incubation with a DKT active component Japanese Pepper increased the mRNA and protein expression levels of TRPA1 in InMyoFibs, which in turn negatively regulated collagen synthesis. In the stenotic regions of the intestines of CD patients, TRPA1 expression was significantly enhanced.

CONCLUSION

The effects of DKT on the expression and activation of the TRPA1 channel could be advantageous for suppressing intestinal fibrosis, and benefit inflammatory bowel disease treatment.

Crohn's disease associated strictures

Crohn's disease (CD) is a chronic relapsing and remitting disease that can affect any segments of the gastrointestinal tract. More than 50% of patients with CD develop stricturing or penetrating complications within the first 10 years after diagnosis. Strictures can lead to intestinal obstruction, which is a common indication for surgery. Despite significant advances in the understanding of the pathogenesis of intestinal fibrostenosis, imaging and therapeutic armamentarium of CD, the risk of intestinal surgery remained significantly high. Endoscopic balloon dilation is a promising first-line alternative to surgery as it is less invasive and could preserve intestinal length. In this review, we will evaluate the literature on the mechanism of intestinal fibrosis, emerging imaging techniques, and management strategies for CD associated strictures.

Parathyroid Hormone-Like Hormone Induces Epithelial-to-Mesenchymal Transition of Intestinal Epithelial Cells by Activating the Runt-Related Transcription Factor 2

Epithelial-to-mesenchymal transition (EMT) is a key contributor to fibroblast activation in fibrosis of multiple organs, including the intestine. Parathyroid hormone-like hormone (PTHLH) is an important factor in renal fibrosis and regulates several processes, including EMT. Herein, we investigated the role of PTHLH-induced EMT in intestinal fibrosis associated with Crohn disease. The expression levels of the EMT-related proteins, PTHLH, and parathyroid hormone receptor 1 (PTH1R) in intestinal tissues were determined by immunohistochemistry, and our results revealed that PTHLH and PTH1R were significantly elevated and associated with EMT marker expression. Moreover, neutralizing PTH1R and antagonizing PTHLH bioactivity prevented transforming growth factor-β1-induced EMT. PTH1R can propagate the protein kinase A (PKA) signal and activate downstream nuclear transcription factors, including runt-related transcription factor 2 (Runx2). In addition, lentiviral vector-PTHLH-treated mice were highly sensitive to 2,4,6-trinitrobenzene sulfonic acid, and analysis of the PTHLH-PTH1R axis revealed the involvement of PKA-Runx2 in PTHLH-induced EMT. Our results indicate that PTHLH triggered EMT in intestinal epithelial cells through the PKA-Runx2 pathway, which might serve as a therapeutic target for intestinal fibrosis in Crohn disease.

Activation of Myofibroblast TRPA1 by Steroids and Pirfenidone Ameliorates Fibrosis in Experimental Crohn's Disease

BACKGROUND & AIMS

The transient receptor potential ankyrin 1 (TRPA1) channel is highly expressed in the intestinal lamina propria, but its contribution to gut physiology/pathophysiology is unclear. Here, we evaluated the function of myofibroblast TRPA1 channels in intestinal remodeling.

METHODS

An intestinal myofibroblast cell line (InMyoFibs) was stimulated by transforming growth factor-β1 to induce in vitro fibrosis. Trpa1 knockout mice were generated using the Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system. A murine chronic colitis model was established by weekly intrarectal trinitrobenzene sulfonic acid (TNBS) administration. Samples from the intestines of Crohn's disease (CD) patients were used for pathologic staining and quantitative analyses.

RESULTS

In InMyoFibs, TRPA1 showed the highest expression among TRP family members. In TNBS chronic colitis model mice, the extents of inflammation and fibrotic changes were more prominent in TRPA1^-/- knockout than in wild-type mice. One-week enema administration of prednisolone suppressed fibrotic lesions in wild-type mice, but not in TRPA1 knockout mice. Steroids and pirfenidone induced Ca²⁺ influx in InMyoFibs, which was antagonized by the selective TRPA1 channel blocker HC-030031. Steroids and pirfenidone counteracted transforming growth factor-β1-induced expression of heat shock protein 47, type 1 collagen, and α-smooth muscle actin, and reduced Smad-2 phosphorylation and myocardin expression in InMyoFibs. In stenotic intestinal regions of CD patients, TRPA1 expression was increased significantly. TRPA1/heat shock protein 47 double-positive cells accumulated in the stenotic intestinal regions of both CD patients and TNBS-treated mice.

CONCLUSIONS

TRPA1, in addition to its anti-inflammatory actions, may protect against intestinal fibrosis, thus being a novel therapeutic target for highly incurable inflammatory/fibrotic disorders.

TL1A blocking ameliorates intestinal fibrosis in the T cell transfer model of chronic colitis in mice

Tumor necrosis factor like cytokine 1A (TL1A) is a member of the TNF superfamily. Accumulating evidence demonstrated the importance of TL1A in the pathogenesis of inflammatory bowel disease (IBD) and suggested a potential role of TL1A blocking in IBD therapy. Here we aimed to explore whether the anti-TL1A antibody could ameliorate intestinal inflammation and fibrosis in IBD. A T cell transfer model of chronic colitis was induced by intraperitoneal injection of CD4⁺CD45RB^high naive T cells isolated from either C57BL/6 wild type (WT) mice or LCK-CD2-Tl1a-GFP transgenic (L-Tg) mice into recombinase activating gene-1-deficient (RAG^-/-) mice. The colitis model mice were treated prophylactically or therapeutically with anti-Tl1a antibody or IgG isotype control. Haematoxylin and eosin staining (H&E staining), Masson's trichrome staining (MT staining) and sirius red staining were used to detect histopathological changes in colonic tissue; immunohistochemical staining was used to detect the expressions of collagen I, collagen III, TIMP1, vimentin, α-SMA and TGF-β1/Smad3. Results showed that anti-Tl1a antibody could reduce intestinal inflammation and fibrosis by inhibiting the activation of intestinal fibroblasts and reducing the collagen synthesis in the T cell transfer model of chronic colitis. The mechanism may be related to the inhibition of TGF-1/Smad3 signaling pathway.

Cinaciguat ameliorates glomerular damage by reducing ERK1/2 activity and TGF-ß expression in type-1 diabetic rats

Decreased soluble guanylate cyclase activity and cGMP levels in diabetic kidneys were shown to influence the progression of nephropathy. The regulatory effects of soluble guanylate cyclase activators on renal signaling pathways are still unknown, we therefore investigated the renal molecular effects of the soluble guanylate cyclase activator cinaciguat in type-1 diabetic (T1DM) rats. Male adult Sprague-Dawley rats were divided into 2 groups after induction of T1DM with 60 mg/kg streptozotocin: DM, untreated (DM, n = 8) and 2) DM + cinaciguat (10 mg/kg per os daily, DM-Cin, n = 8). Non-diabetic untreated and cinaciguat treated rats served as controls (Co (n = 10) and Co-Cin (n = 10), respectively). Rats were treated for eight weeks, when renal functional and molecular analyses were performed. Cinaciguat attenuated the diabetes induced proteinuria, glomerulosclerosis and renal collagen-IV expression accompanied by 50% reduction of TIMP-1 expression. Cinaciguat treatment restored the glomerular cGMP content and soluble guanylate cyclase expression, and ameliorated the glomerular apoptosis (TUNEL positive cell number) and podocyte injury. These effects were accompanied by significantly reduced TGF-ß overexpression and ERK1/2 phosphorylation in cinaciguat treated diabetic kidneys. We conclude that the soluble guanylate cyclase activator cinaciguat ameliorated diabetes induced glomerular damage, apoptosis, podocyte injury and TIMP-1 overexpression by suppressing TGF-ß and ERK1/2 signaling.

Significant contribution of TRPC6 channel-mediated Ca2+ influx to the pathogenesis of Crohn's disease fibrotic stenosis

Intestinal fibrosis is an intractable complication of Crohn's disease (CD), and, when occurring excessively, causes severe intestinal obstruction that often necessitates surgical resection. The fibrosis is characterized by an imbalance in the turnover of extracellular matrix (ECM) components, where intestinal fibroblasts/myofibroblasts play active roles in ECM production, fibrogenesis and tissue remodeling, which eventually leads to the formation of stenotic lesions. There is however a great paucity of knowledge about how intestinal fibrosis initiates and progresses, which hampers the development of effective pharmacotherapies against CD. Recently, we explored the potential implications of transient receptor potential (TRP) channels in the pathogenesis of intestinal fibrosis, since they are known to act as cellular stress sensors/transducers affecting intracellular Ca²⁺ homeostasis/dynamics, and are involved in a broad spectrum of cell pathophysiology including inflammation and tissue remodeling. In this review, we will place a particular emphasis on the intestinal fibroblast/myofibroblast TRPC6 channel to discuss its modulatory effects on fibrotic responses and therapeutic potential for anti-fibrotic treatment against CD-related stenosis.

Prenylated flavonoid morusin protects against TNBS-induced colitis in rats

Morusin is a prenylated flavonoid isolated from the root bark of Morus alba. Many studies have shown the ability of flavonoids to act as anti-inflammatory agents. The aim of this study was to evaluate the effect of morusin on experimentally colitis induced by 2,4,6-trinitrobenzensulfonic acid in Wistar rats and to compare it with sulfasalazine, a drug conventionally used in the treatment of inflammatory bowel disease. Morusin was administered by gavage at doses of 12.5, 25, or 50 mg/kg/day for five days. The colonic tissue was evaluated macroscopically, histologically, and by performing immunodetection and zymographic analysis to determine the levels of antioxidant enzymes [superoxide dismutase (SOD) and catalase (CAT)], interleukin (IL)-1β, and transforming growth factor (TGF)-β1 and the activities of matrix metalloproteinases (MMP) 2 and 9. The tissue damage scores were significantly reduced with increasing dose of morusin, however efficacy was not demonstrated at the highest dose. At the dose of 12.5 mg/kg, morusin exerted therapeutic effectivity similar to that of sulfasalazine (50 mg/kg). This was associated with significant reduction of TGF-β1 levels and MMP2 and MMP9 activities, and slight reduction of IL-1β. Our results suggest that morusin possesses therapeutic potential for the treatment of chronic inflammatory diseases.

Advanced Oxidation Protein Products Induce Epithelial-Mesenchymal Transition of Intestinal Epithelial Cells via a PKC δ-Mediated, Redox-Dependent Signaling Pathway

AIMS

Epithelial-mesenchymal transition (EMT) has been considered a fundamental mechanism in complications of Crohn's disease (CD), especially intestinal fibrosis. However, the mechanism underlying EMT regulation in intestinal fibrosis remains unclear. This study aimed to investigate the role of advanced oxidation protein products (AOPPs) in the occurrence of intestinal EMT.

RESULTS

AOPPs accumulated in CD tissues and were associated with EMT marker expression in fibrotic lesions from CD patients. Challenge with AOPPs induced intestinal epithelial cell (IEC) phenotype transdifferentiation, fibroblast-like phenotype acquisition, and production of extracellular matrix, both in vitro and in vivo. The effect of AOPPs was mainly mediated by a protein kinase C (PKC) δ-mediated redox-dependent pathway, including phosphorylation of PKC δ, recruitment of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, production of reactive oxygen species, and NF-κB p65 activation. Inhibition of AOPP-redox signaling activation effectively blocked AOPP-induced EMT in vitro. Studies performed in normal rats showed that chronic administration of AOPPs triggered the occurrence of EMT in rat intestinal epithelia, accompanied by disruption of intestinal integrity, and by promotion of collagen deposition. These effects could be reversed by inhibition of NADPH oxidase. Innovation and Conclusion: This is the first study to demonstrate that AOPPs triggered the occurrence of EMT in IECs in vitro and in vivo through PKC δ-mediated redox-dependent signaling. Our study identifies the role of AOPPs and, in turn, EMT in intestinal fibrosis and provides novel potential targets for the treatment of intestinal fibrotic diseases. Antioxid. Redox Signal. 27, 37-56.

The crucial role of activin A/ALK4 pathway in the pathogenesis of Ang-II-induced atrial fibrosis and vulnerability to atrial fibrillation

Atrial fibrosis, the hallmark of structural remodeling associated with atrial fibrillation (AF), is characterized by abnormal proliferation of atrial fibroblasts and excessive deposition of extracellular matrix. Transforming growth factor-β1 (TGF-β1)/activin receptor-like kinase 5 (ALK5)/Smad2/3/4 pathway has been reported to be involved in the process. Recent studies have implicated both activin A and its specific downstream component activin receptor-like kinase 4 (ALK4) in stimulating fibrosis in non-cardiac organs. We recently reported that ALK4 haplodeficiency attenuated the pressure overload- and myocardial infarction-induced ventricular fibrosis. However, the role of activin A/ALK4 in the pathogenesis of atrial fibrosis and vulnerability to AF remains unknown. Our study provided experimental and clinical evidence for the involvement of activin A and ALK4 in the pathophysiology of atrial fibrosis and AF. Patients with AF had higher activin A and ALK4 expression in atriums as compared to individuals devoid of AF. After angiotensin-II (Ang-II) stimulation which mimicked atrial fibrosis progression, ALK4-deficient mice showed lower expression of ALK4 in atriums, reduced activation of atrial fibroblasts, blunted atrial enlargement and atrial fibrosis, and further reduced AF vulnerability upon right atrial electrophysiological studies as compared to wild-type littermates. Moreover, we found that apart from the well-known TGF-β1/ALK5 pathway, the activation of activin A/ALK4/smad2/3 pathway played an important role in the pathogenesis of Ang-II-mediated atrial fibrosis and inducibility of AF, suggesting that targeting ALK4 might be a potential therapy for atrial fibrosis and AF.

Crosstalk between Smad2/3 and specific isoforms of ERK in TGF-β1-induced TIMP-3 expression in rat chondrocytes

This study investigated the roles of ERK1 and ERK2 in transforming growth factor‐β1 (TGF‐β1)‐induced tissue inhibitor of metalloproteinases‐3 (TIMP‐3) expression in rat chondrocytes, and the specific roles of ERK1 and ERK2 in crosstalk with Smad2/3 were investigated to demonstrate the molecular mechanism of ERK1/2 regulation of TGF‐β1 signalling. To examine the interaction of specific isoforms of ERK and the Smad2/3 signalling pathway, chondrocytes were infected with LV expressing either ERK1 or ERK2 siRNA and stimulated with or without TGF‐β1. At indicated time‐points, TIMP‐3 expression was determined by real‐time PCR and Western blotting; p‐Smad3, nuclear p‐Smad3, Smad2/3, p‐ERK1/2 and ERK1/2 levels were assessed. And then, aggrecan, type II collagen and the intensity of matrix were examined. TGF‐β1‐induced TIMP‐3 expression was significantly inhibited by ERK1 knock‐down, and the decrease in TIMP‐3 expression was accompanied by a reduction of p‐Smad3 in ERK1 knock‐down cells. Knock‐down of ERK2 had no effect on neither TGF‐β1‐induced TIMP‐3 expression nor the quantity of p‐Smad3. Moreover, aggrecan, type II collagen expression and the intensity of matrix were significantly suppressed by ERK1 knock‐down instead of ERK2 knock‐down. Taken together, ERK1 and ERK2 have different roles in TGF‐β1‐induced TIMP‐3 expression in rat chondrocytes. ERK1 instead of ERK2 can regulate TGF‐β/Smad signalling, which may be the mechanism through which ERK1 regulates TGF‐β1‐induced TIMP‐3 expression.

Crohn's Strictures-Moving Away from the Knife

Crohn's disease (CD) is a lifelong inflammatory bowel disease with a rapidly rising incidence in the pediatric population. A common complication of CD is the development of fibrotic strictures, which may be present at initial diagnosis or develop many years later. Clinical presentation depends on stricture location and degree of obstruction, and strictures frequently contain a mixture of inflammatory and fibrotic tissue. Histological examination of Crohn's strictures shows thickening of the muscular layers and the submucosa, where increased collagen deposition by activated myofibroblasts is concentrated around islands of smooth muscle cells and at the superficial margin of the muscularis propria. No antifibrotic therapies for Crohn's strictures exist. Profibrotic transforming growth factor-β (TGFβ)/bone morphogenetic protein signaling stimulates myofibroblast differentiation and extracellular matrix deposition. Understanding and targeting TGFβ1 downstream signaling is the main focus of current research, raising the possibility of specific antifibrotic therapy in CD becoming available in the future.

Lentiviral Vector-Mediated FoxO1 Overexpression Inhibits Extracellular Matrix Protein Secretion Under High Glucose Conditions in Mesangial Cells

Diabetic nephropathy is characterized by inordinate secretion of extracellular matrix (ECM) proteins from mesangial cells (MCs), which is tightly associated with excessive activation of TGF-β signaling. The forkhead transcription factor O1 (FoxO1) protects mesangial cells from hyperglycemia-induced oxidative stress, which may be involved in ameliorating the redundant secretion of ECM proteins under high glucose conditions. Here, we reported that high glucose elevated the level of p-Akt to attenuate endogenous FoxO1 bioactivities in MCs, accompanied with decreases in the mRNA expressions of catalase (CAT) and superoxide dismutase 2 (SOD2). Meanwhile, the expressions of major ECM proteins-FN and Col I-increased under high glucose conditions, in consistent with the activation of TGF-β/Smad signaling. By contrast, overexpression of nucleus-localized FoxO1 (insensitive to Akt phosphorylation) directly up-regulated the expressions of anti-oxidative enzymes, accompanied with inactivation of TGF-β/Smad3 pathway, as well as decreases of extracellular matrix proteins. Moreover, similar to those MCs overexpressed of nucleus-localized FoxO1 in high glucose conditions, MCs with down-regulation of FoxO1 by small interference-RNA under normal glucose conditions showed increased FN level and activated TGF-β/Smad3 pathway. Our findings link the anti-oxidative activity of FoxO1 and the TGF-β-induced secretion of ECM proteins, indicating the novel role of FoxO1 in protecting MCs under high glucose conditions.

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.

Will novel oral formulations change the management of inflammatory bowel disease?

INTRODUCTION

The traditional management of inflammatory bowel disease (IBD) with sulphasalazine/5-aminosalicylic acid, glucocorticoids and immunomodulators (i.e., thiopurines and methotrexate) was nearly two decades ago extended with intravenously or subcutaneously administered biologics (i.e., tumor necrosis factor inhibitors and later gut-selective integrin antagonists). However, recently, orally administered treatments with simple, well-characterized, and stable structures consisting of either small molecules or anti-sense therapy have been devised.

AREAS COVERED

This review discusses the current approaches with promising new oral drugs with distinct modes of action, including: the Janus kinase inhibitors (i.e., tofacitinib, filgotinib and peficitinib); the immunomodulatory drug (laquinimod); a small α4 antagonist (AJM300); agonists for sphingosine-phosphate receptors (i.e., ozanimod, APD334, and amiselimod), as well as anti-sense therapy (mongersen) targeting SMAD7, drugs which directly target intracellular pathways of relevance for intestinal inflammation.

EXPERT OPINION

A new avenue using easily administered oral therapies for the management of IBD is being introduced. While their place in the clinical armamentarium remains to be proven, it is likely that many of these drugs will find their place in the treatment algorithm of IBD in the next few years. Thus, we will face times in which IBD therapy will be based on significantly more tablets than prescribed today.

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.

Overexpression of the FoxO1 Ameliorates Mesangial Cell Dysfunction in Male Diabetic Rats

The dysfunction of mesangial cells (MCs) in high-glucose (HG) conditions plays pivotal role in inducing glomerular sclerosis by causing the imbalance between generation and degradation of extracellular matrix (ECM) proteins, which ultimately leads to diabetic nephropathy. This study was designed to determine the function of forkhead box protein O1 (FoxO1), an important transcription factors in regulating cell metabolism and oxidative stress, in MCs in HG conditions. Up-regulation of fibronectin, collagen type IV, and plasminogen activator inhibitor (PAI-1) was observed under HG conditions in vivo and in vitro, accompanied with elevation of protein kinase B (Akt) phosphorylation and reduction of FoxO1 bioactivity. After overexpression of constitutively active (CA) FoxO1 in vivo and in vitro by using lentivirus vector, in vivo and in vitro, FoxO1 expression and activity was increased, in accordance with up-regulation of antioxidative genes (catalase and superoxide dismutase, leading to alleviated oxidative stress as well as attenuated Akt activity, whereas overexpression of wild type-FoxO1 only expressed partial effect. Moreover, CA-FoxO1 decreased the expression of fibronectin, collagen type IV, and PAI-1, causing amelioration of renal pathological changes and decrease of ECM protein deposition in glomerulus. Overexpression of CA-FoxO1 in renal cortex also decreased activin type-I receptor-like kinase-5 levels and increased signaling mothers against decapentaplegic (Smad) 7 levels, and simultaneously inhibited Smad3 phosphorylation. Results from in vitro study indicated that increased combination of FoxO1 and Smad3 may interfere with the function of Smad3, including Smad3 phosphorylation and translocation, interaction with cAMP response element binding protein (CREB)-binding protein, and binding with PAI-1 promoter. Together, our findings shed light on the novel function of FoxO1 in inhibiting ECM deposition, which is beneficial to ameliorate MC dysfunction.