Infliximab therapy inhibits inflammation-induced angiogenesis in the mucosa of patients with Crohn's disease

Understanding the therapeutic toolkit for inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis and Crohn's disease, is a group of chronic, immune-mediated disorders of the gastrointestinal tract that present substantial clinical challenges owing to their complex pathophysiology and tendency to relapse. A treat-to-target approach is recommended, involving iterative treatment adjustments to achieve clinical response, reduce inflammatory markers and achieve long-term goals such as mucosal healing. Lifelong medication is often necessary to manage the disease, maintain remission and prevent complications. The therapeutic landscape for IBD has evolved substantially; however, a ceiling on therapeutic efficacy remains and surgery is sometimes required (owing to uncontrolled disease activity or complications). Effective IBD management involves comprehensive care, including medication adherence and a collaborative clinician-patient relationship. This Review discusses current therapeutic options for IBD, detailing mechanisms of action, efficacy, safety profiles and guidelines for use of each drug class. We also explore emerging therapies and the role of surgery. Additionally, the importance of a multidisciplinary team and personalized care in managing IBD is emphasized, advocating for patient empowerment and involvement in treatment decisions. By synthesizing current knowledge and emerging trends, this Review aims to equip healthcare professionals with a thorough understanding of therapeutic options for IBD, enhancing informed, evidence-based decisions in clinical practice.

Identification of Angiogenesis-Related Gene Signatures and Prediction of Potential Therapeutic Targets in Ulcerative Colitis Using Integrated Bioinformatics

Objective

This study aims to clarify angiogenesis mechanisms in ulcerative colitis and identify potential therapeutic targets.

Methods

The Gene Expression Omnibus (GEO) database was used to obtain expression profiles and clinical data for UC and healthy colon tissues. Angiogenesis-related gene sets were acquired from GeneCards. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) identified UC-associated hub genes. The CIBERSORT algorithm assessed immune cell infiltration. Analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed to determine biological mechanisms. External datasets were utilized to validate and characterize the angiogenesis-related genes in relation to biological agents. Additionally, an ulcerative colitis mouse model was constructed to verify the key genes' expression using real-time quantitative PCR. To predict potential therapeutic agents, we used the DGIdb database. Molecular docking modeled small molecule binding conformations to key gene targets.

Results

This study identified 1,247 DEGs enriched in inflammatory/immune pathways from UC and healthy colon samples. WGCNA indicated the black and light cyan modules were most relevant. Intersecting these with 89 angiogenesis genes revealed 5 UC-associated hub genes (pdgfrb, vegfc, angpt2, tnc, hgf). Validation via ROC analysis, differential expression, and a mouse model confirmed upregulation, supporting their potential as UC diagnostic biomarkers. Bioinformatics approaches like protein-protein interaction, enrichment analysis, and GSEA revealed involvement in PDGFR and PI3K-Akt signaling pathways. CIBERSORT analysis of immune cell infiltration showed positive correlations between the key genes and various immune cells, especially neutrophils, highlighting angiogenesis-inflammation interplay in UC. A ceRNA network was constructed. Drug prediction and molecular docking revealed potential UC therapies like sunitinib and imatinib targeting angiogenesis.

Conclusion

This study identified and validated five angiogenesis-related genes (pdgfrb, vegfc, angpt2, tnc, hgf) that may serve as diagnostic biomarkers and drug targets for UC.

Chemoprophylaxis of precancerous lesions in patients who are at a high risk of developing colorectal cancer (Review)

The diagnostics of colorectal cancer (CRC) and precancerous lesions in the colon is one of the most urgent matters to be considered for the modern protocols of complex examination, recommended for use from the age of 45 years, and including both instrumental and laboratory methods of research: Colonoscopy, CT colonography, flexible sigmoidoscopy, fecal occult blood test, fecal immunohistochemistry test and stool DNA test Nevertheless, the removal of those precancerous lesions does not solve the issue, and, apart from the regular endoscopic monitoring of patients who are at a high risk of developing CRC, the pharmacological treatment of certain key pathogenic mechanisms leading to the development of CRC is required. The present review to discusses the function of β-catenin in the transformation of precancerous colorectal lesions into CRC, when collaborating with PI3K/AKT/mTOR signaling pathway and other mechanisms. The existing methods for the early diagnostics and prevention of discovered anomalies are described and categorized. The analysis of the approaches to chemoprophylaxis of CRC, depending on the results of endoscopic, morphological and molecular-genetic tests, is presented.

Infliximab therapy decreases the expression of serum and faecal miR-126 and miR-20a in paediatric Crohn's disease: A pilot study

AIM

We aimed to evaluate the serum and faecal expression of miR-126 and miR-20a in children with Crohn's disease (CD) during infliximab (IFX) therapy.

METHODS

In this prospective observational study, serum and faeces from CD patients were collected before IFX therapy (T0), after induction (T1) and after 6 months from IFX (T2). IFX levels were determined by Enzyme-linked immunosorbent assay at T1 and T2. miRNAs were profiled through Real-Time RT-PCR. The activity of disease was evaluated through the Paediatric Crohn's disease activity index (PCDAI), serum C-reactive protein (CRP) and faecal calprotectin.

RESULTS

Nine CD children were enrolled. Serum and faecal miR-126 and miR-20a levels were higher at T0 and showed a time-dependent decrease, being significantly down-regulated after IFX treatment at T2. Specifically, IFX levels recorded at T1 and T2 negatively correlated with the serum and faecal expression of miR-126 and miR-20a. Serum and faecal changes of miR-126 and miR20-a were positively associated with the decrease of the inflammatory marker CRP and PDCAI at all time points.

CONCLUSION

In children with CD, IFX therapy decreases the expression of serum and faecal miR-126 and miR-20a, suggesting an involvement of these two miRNAs in the action of the drug.

Urokinase-type plasminogen activator blockade ameliorates experimental colitis in mice

Although several angiogenesis-related factors are reportedly involved in the pathogenesis of ulcerative colitis (UC), the mechanisms by which they contribute to disease are unclear. We first examined the expression of angiogenesis-related factors in inflamed colorectal tissue of UC patients using antibody array, and identified the 5 factors with highest expression, which included matrix metalloproteinase-8, urokinase-type plasminogen activator (uPA), angiostatin/plasminogen, hepatocyte growth factor and endoglin. Subsequent real-time PCR experiments using additional colorectal tissues revealed that uPA mRNA levels were significantly higher in inflamed tissues than in non-inflamed tissues, and significantly correlated with the severity of UC. Mirror section immunohistochemistry revealed that uPA was expressed in the neutrophils of inflamed colorectal tissues. We administered dextran sulfate sodium (DSS) in drinking water to uPA knockout (uPA^-/-) mice, and found that the disease activity index in uPA^-/- mice was marginally lower and the histological score in uPA^-/- mice was significantly lower than those in wild-type mice, suggesting the importance of uPA in colitis. When an uPA-selective inhibitor, UK122, was administered to DSS-treated C57BL6J mice, the disease activity index and histological score in those mice were significantly lower compared with control mice. Multiple cytokine/chemokine assay using colorectal tissues from uPA^-/- and UK122-treated mice revealed significantly lowered level of RANTES. In conclusion, uPA was highly expressed in neutrophils of the inflamed mucosa of UC patients, and the expression level correlated with the severity of UC. Genetic uPA deletion or pharmacological uPA blockade significantly ameliorated colitis in mice, concomitant with downregulation of RANTES.

Inflammatory Bowel Disease Treatments and Predictive Biomarkers of Therapeutic Response

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammation of the gastrointestinal tract with a highly heterogeneous presentation. It has a relapsing and remitting clinical course that necessitates lifelong monitoring and treatment. Although the availability of a variety of effective therapeutic options including immunomodulators and biologics (such as TNF, CAM inhibitors) has led to a paradigm shift in the treatment outcomes and clinical management of IBD patients, some patients still either fail to respond or lose their responsiveness to therapy over time. Therefore, according to the recent Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE-II) recommendations, continuous disease monitoring from symptomatic relief to endoscopic healing along with short- and long-term therapeutic responses are critical for providing IBD patients with a tailored therapy algorithm. Moreover, considering the high unmet need for novel therapeutic approaches for IBD patients, various new modulators of cytokine signaling events (for example, JAK/TYK inhibitors), inhibitors of cytokines (for example IL-12/IL-23, IL-22, IL-36, and IL-6 inhibitors), anti-adhesion and migration strategies (for example, β7 integrin, sphingosine 1-phosphate receptors, and stem cells), as well as microbial-based therapeutics to decolonize the bed buds (for example, fecal microbiota transplantation and bacterial inhibitors) are currently being evaluated in different phases of controlled clinical trials. This review aims to offer a comprehensive overview of available treatment options and emerging therapeutic approaches for IBD patients. Furthermore, predictive biomarkers for monitoring the therapeutic response to different IBD therapies are also discussed.

Biological Treatments in Inflammatory Bowel Disease: A Complex Mix of Mechanisms and Actions

Inflammatory bowel disease (IBD) is a chronic disease that requires lifelong medication and whose incidence is increasing over the world. There is currently no cure for IBD, and the current therapeutic objective is to control the inflammatory process. Approximately one third of treated patients do not respond to treatment and refractoriness to treatment is common. Therefore, pharmacological treatments, such as monoclonal antibodies, are urgently needed, and new treatment guidelines are regularly published. Due to the extremely important current role of biologics in the therapy of IBD, herein we have briefly reviewed the main biological treatments currently available. In addition, we have focused on the mechanisms of action of the most relevant groups of biological agents in IBD therapy, which are not completely clear but are undoubtfully important for understanding both their therapeutic efficacy and the adverse side effects they may have. Further studies are necessary to better understand the action mechanism of these drugs, which will in turn help us to understand how to improve their efficacy and safety. These studies will hopefully pave the path for a personalized medicine.

Effects of Anti-Inflammatory Treatment and Surgical Intervention on Endothelial Glycocalyx, Peripheral and Coronary Microcirculatory Function and Myocardial Deformation in Inflammatory Bowel Disease Patients: A Two-Arms Two-Stage Clinical Trial

Sixty inflammatory bowel disease (IBD) patients (45 Crohn disease and 15 ulcerative colitis, 40 ± 13 years, 53% male) were examined at baseline and 4 months after intervention (surgical (35 patients) or anti-TNFa treatment (25 patients)). IBD severity, using Mayo score, Harvey–Bradshaw Index (HBI) and biomarkers, was correlated with cardiovascular markers. At baseline, the disease severity, the white blood cells (WBC) values and the reducing power (RP) were significantly correlated with the aortic pulse wave velocity (PWV) (r = 0.4, r = 0.44 and r = 0.48, p < 0.05) and the lateral mitral E’ velocity (r = 0.35, p < 0.05 and r = 0.3, p < 0.05). Four months after intervention, there was a reduction of WBC (1962.8/mm³ ± 0.425/mm³, p < 0.001), C-reactive protein (CRP) (8.1 mg/L ± 1.7 mg/L, p < 0.001), malondialdehyde (MDA) (0.81 nmol/mg ± 0.37, p < 0.05) and glycocalyx perfused boundary region (PBR 5-25) (0.24 μm ± 0.05 μm, p < 0.01). Moreover, the brachial flow mediated dilatation (FMD), the coronary flow reserve (CFR) and the left ventricle global longitudinal strain (LV GLS) were significantly improved for both groups (4.5% ± 0.9%, 0.55 ± 0.08, 1.4% ± 0.35%, p < 0.01), while a more significant improvement of PWV/GLS was noticed in the anti-TNFa group. IBD severity is associated with vascular endothelial, cardiac diastolic, and coronary microcirculatory dysfunction. The systemic inflammatory inhibition and the local surgical intervention lead to significant improvement in endothelial function, coronary microcirculation and myocardial deformation.

Arginase impedes the resolution of colitis by altering the microbiome and metabolome

Arginase 1 (Arg1), which converts l-arginine into ornithine and urea, exerts pleiotropic immunoregulatory effects. However, the function of Arg1 in inflammatory bowel disease (IBD) remains poorly characterized. Here, we found that Arg1 expression correlated with the degree of inflammation in intestinal tissues from IBD patients. In mice, Arg1 was upregulated in an IL-4/IL-13- and intestinal microbiota-dependent manner. Tie2-Cre Arg1fl/fl mice lacking Arg1 in hematopoietic and endothelial cells recovered faster from colitis than Arg1-expressing (Arg1fl/fl) littermates. This correlated with decreased vessel density, compositional changes in intestinal microbiota, diminished infiltration by myeloid cells, and an accumulation of intraluminal polyamines that promote epithelial healing. The proresolving effect of Arg1 deletion was reduced by an l-arginine-free diet, but rescued by simultaneous deletion of other l-arginine-metabolizing enzymes, such as Arg2 or Nos2, demonstrating that protection from colitis requires l-arginine. Fecal microbiota transfers from Tie2-Cre Arg1fl/fl mice into WT recipients ameliorated intestinal inflammation, while transfers from WT littermates into Arg1-deficient mice prevented an advanced recovery from colitis. Thus, an increased availability of l-arginine as well as altered intestinal microbiota and metabolic products accounts for the accelerated resolution from colitis in the absence of Arg1. Consequently, l-arginine metabolism may serve as a target for clinical intervention in IBD patients.

Endothelial and Cardiac Dysfunction in Inflammatory Bowel Diseases: Does Treatment Modify the Inflammatory Load on Arterial and Cardiac Structure and Function?

Inflammatory bowel diseases (IBD), largely represented by Crohn's disease (CD) and ulcerative colitis (UC), alter gastrointestinal physiology and mucosal immunity through a complex inflammatory process. These diseases can lead to significant arterial endothelial dysfunction. There is also evidence linking IBD with a modification of cardiac structure and function. A growing body of research has associated IBD with an acceleration of arterial stiffness and atherosclerosis and an increased risk of cardiovascular (CV) morbidity and mortality. The focus of this review is two-fold. Firstly, the literature on IBD in relation to CV dysfunction was evaluated (mainly based on 25 relevant surveys carried out between 2005 and 2018). The vast majority of these studies support a significant association of IBD with a deterioration in CV function. Secondly, the literature available regarding the effect of IBD treatment on CV dysfunction was considered based on studies published between 2007 and 2018. This literature search suggests that IBD treatment may have the potential to ameliorate CV dysfunction resulting in CV benefits. This review will analyse the literature as well as consider emerging research perspectives regarding how IBD treatment could improve CV dysfunction.

Factors Influencing Drug Disposition of Monoclonal Antibodies in Inflammatory Bowel Disease: Implications for Personalized Medicine

Monoclonal antibody (mAb) therapies have revolutionized the treatment of several chronic inflammatory diseases, including the inflammatory bowel diseases (IBD), Crohn's disease, and ulcerative colitis. While efficacious, responses to these therapies vary considerably from patient to patient, due in part to inter- and intra-individual variability in pharmacokinetics (PK) and drug exposure. The concept of personalized medicine to monitor drug exposure and to adjust dosing in individual patients is consequently gaining acceptance as a powerful tool to optimize mAb therapy for improved outcomes in IBD. This review provides a brief overview of the different mAbs currently approved or in development for the treatment of IBD, including their presumed mechanisms of action and PK properties. Specifically described are (1) the factors known to affect mAb PK and drug exposure in patients with IBD, (2) the value of population PK/pharmacodynamic (PD) modeling to identify and understand the influence of these factors on drug exposure and effect, and (3) the clinical evidence for the potential of therapeutic drug monitoring (TDM) to improve IBD outcomes in response to mAb-based therapy. Incorporation of PK/PD parameters into clinical decision support tools has the potential to guide therapeutic decision making and aid implementation of personalized medicine strategies in patients with IBD.

Functional rare variants influence the clinical response to anti-TNF therapy in Crohn's disease

BACKGROUND

The effect of low-frequency functional variation on anti-tumor necrosis factor alpha (TNF) response in Crohn's disease (CD) patients remains unexplored. The objective of this study was to investigate the impact of functional rare variants in clinical response to anti-TNF therapy in CD.

METHODS

CD anti-TNF naïve patients starting anti-TNF treatment due to active disease [Crohn's Disease Activity Index (CDAI > 150)] were included. The whole genome was sequenced using the Illumina Hiseq4000 platform. Clinical response was defined as a CDAI score <150 at week 14 of anti-TNF treatment. Low-frequency variants were annotated and classified according to their damaging potential. The whole genome of CD patients was screened to identify homozygous loss-of-function (LoF) variants. The TNF signaling pathway was tested for overabundance of damaging variants using the SKAT-O method. Functional implication of the associated rare variation was evaluated using cell-type epigenetic enrichment analyses.

RESULTS

A total of 41 consecutive CD patients were included; 3250 functional rare variants were identified (2682 damaging and 568 LoF variants). Two homozygous LoF mutations were found in HLA-B and HLA-DRB1 genes associated with lack of response and remission, respectively. Genome-wide LoF variants were enriched in epigenetic marks specific for the gastrointestinal tissue (colon, p = 4.11e-4; duodenum, p = 0.011). The burden of damaging variation in the TNF signaling pathway was associated with response to anti-TNF therapy (p = 0.016); damaging variants were enriched in epigenetic marks from CD8⁺ (p = 6.01e-4) and CD4+ (p = 0.032) T cells.

CONCLUSIONS

Functional rare variants are involved in the response to anti-TNF therapy in CD. Cell-type enrichment analysis suggests that the gut mucosa and CD8⁺ T cells are the main mediators of this response.

Novel phase I trial design to evaluate the addition of cediranib or selumetinib to preoperative chemoradiotherapy for locally advanced rectal cancer: the DREAMtherapy trial

BACKGROUND

The DREAMtherapy (Dual REctal Angiogenesis MEK inhibition radiotherapy) trial is a novel intertwined design whereby two tyrosine kinase inhibitors (cediranib and selumetinib) were independently evaluated with rectal chemoradiotherapy (CRT) in an efficient manner to limit the extended follow-up period often required for radiotherapy studies.

PATIENTS AND METHODS

Cediranib or selumetinib was commenced 10 days before and then continued with RT (45 Gy/25#/5 wks) and capecitabine (825 mg/m2 twice a day (BID)). When three patients in the cediranib 15-mg once daily (OD) cohort were in the surveillance period, recruitment to the selumetinib cohort commenced. This alternating schedule was followed throughout. Three cediranib (15, 20 and 30 mg OD) and two selumetinib cohorts (50 and 75 mg BID) were planned. Circulating and imaging biomarkers of inflammation/angiogenesis were evaluated.

RESULTS

In case of cediranib, dose-limiting diarrhoea, fatigue and skin reactions were seen in the 30-mg OD cohort, and therefore, 20 mg OD was defined as the maximum tolerated dose. Forty-one percent patients achieved a clinical or pathological complete response (7/17), and 53% (9/17) had an excellent clinical or pathological response (ECPR). Significantly lower level of pre-treatment plasma tumour necrosis factor alpha (TNFα) was found in patients who had an ECPR. In case of selumetinib, the 50-mg BID cohort was poorly tolerated (fatigue and diarrhoea); a reduced dose cohort of 75-mg OD was opened which was also poorly tolerated, and further recruitment was abandoned. Of the 12 patients treated, two attained an ECPR (17%).

CONCLUSIONS

This novel intertwined trial design is an effective way to independently investigate multiple agents with radiotherapy. The combination of cediranib with CRT was well tolerated with encouraging efficacy. TNFα emerged as a potential predictive biomarker of response and warrants further evaluation.

Novel Imaging Approaches in Inflammatory Bowel Diseases

Inflammatory bowel diseases are chronic autoimmune conditions of the gastrointestinal tract, mainly grouped into ulcerative colitis or Crohn's disease. Traditionally, symptoms have been used to guide IBD management, but this approach is fatally flawed, as symptoms don't correlate with disease activity and often fail to predict disease complications, especially with Crohn's disease. Hence, there is increasing recognition of the need for treatment algorithms based on objective measures of bowel inflammation. In this review, we will focus on advancements in the endoscopic and radiological imaging armamentarium that allow detailed assessments from intestinal mucosa to mesentery.

The Innate and Adaptive Immune System as Targets for Biologic Therapies in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory condition causing inflammation of gastrointestinal and systemic cells, with an increasing prevalence worldwide. Many factors are known to trigger and maintain inflammation in IBD including the innate and adaptive immune systems, genetics, the gastrointestinal microbiome and several environmental factors. Our knowledge of the involvement of the immune system in the pathophysiology of IBD has advanced rapidly over the last two decades, leading to the development of several immune-targeted treatments with a biological source, known as biologic agents. The initial focus of these agents was directed against the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) leading to dramatic changes in the disease course for a proportion of patients with IBD. However, more recently, it has been shown that a significant proportion of patients do not respond to anti-TNF-α directed therapies, leading a shift to other inflammatory pathways and targets, including those of both the innate and adaptive immune systems, and targets linking both systems including anti-leukocyte trafficking agents-integrins and adhesion molecules. This review briefly describes the molecular basis of immune based gastrointestinal inflammation in IBD, and then describes how several current and future biologic agents work to manipulate these pathways, and their clinical success to date.

Current and emerging therapeutic targets for IBD

Various therapeutic advances have led to a paradigm shift in the clinical management of patients with IBD. The introduction of immunosuppressive (such as azathioprine) and biologic agents (such as TNF blockers) has markedly reduced the need to use corticosteroids for therapy. Furthermore, the α4β7 integrin blocker vedolizumab has been introduced for clinical IBD therapy. Moreover, various new inhibitors of cytokines (for example, IL-6-IL-6R and IL-12-IL-23 blockers or apremilast), modulators of cytokine signalling events (for example, JAK inhibitors or SMAD7 blocker), inhibitors of transcription factors (for example, GATA3 or RORγt) and new anti-adhesion and anti-T-cell-activation and migration strategies (for example, β7 integrin, sphingosine 1-phosphate receptors and MAdCAM1 inhibitors, regulatory T-cell therapy and stem cells) are currently being evaluated in controlled clinical trials. This Review aims to provide a comprehensive overview about current and future therapeutic approaches for IBD therapy. Furthermore, potential mechanisms of action of these therapeutic approaches and their implications for clinical therapy in IBD are discussed.

Expression and Localization of miR-21 and miR-126 in Mucosal Tissue from Patients with Inflammatory Bowel Disease

BACKGROUND

microRNAs (miRNAs) are small noncoding RNAs that guide degradation of mRNA and regulate protein expression. miRNA based diagnostic biomarkers for ulcerative colitis (UC) and Crohn's disease (CD) are emerging but information about the cellular localization of many miRNAs is limited and more detailed histologic evaluation of miRNA expression patterns is needed to understand their immunobiological function.

METHODS

Formalin-fixed paraffin-embedded colon biopsies from 10 patients with UC and 8 patients with CD together with 9 controls were examined by RT-qPCR and quantitative in situ hybridization (ISH). The cellular expression of miR-21 positive cells was further characterized using immunohistochemical cellular markers.

RESULTS

Increased levels of miR-21 and miR-126 were found in UC compared with controls and increased levels of miR-21 were observed in UC compared with CD by both RT-qPCR and quantitative in situ hybridization. miR-126 was localized to endothelial cells and miR-21 to cells in the lamina propria. Multiplex immunohistochemical staining showed miR-21 expression in subsets of CD68 macrophages and CD3 T cells in UC, however, far the majority of the miR-21 positive cells could not be categorized among CD68, CD3, and CD19 cells.

CONCLUSIONS

This study shows that miR-126 levels are increased in UC and expressed in endothelial cells. miR-21 is expressed in subsets of monocytes/macrophages and T cells and may work as a potential biomarker to distinguish UC from CD. Quantitative in situ hybridization may be a powerful tool for such analysis as it combines overall expression with validation of cellular origin. Studies in larger cohorts may confirm this for clinical diagnostics.

Molecular mechanism of action of anti-tumor necrosis factor antibodies in inflammatory bowel diseases

Anti-tumor necrosis factor (TNF) antibodies are successfully used in the therapy of inflammatory bowel diseases (IBD). However, the molecular mechanism of action of these agents is still a matter of debate. Apart from neutralization of TNF, influence on the intestinal barrier function, induction of apoptosis in mucosal immune cells, formation of regulatory macrophages as well as other immune modulating properties have been discussed as central features. Nevertheless, clinically effective anti-TNF antibodies were shown to differ in their mode-of-action in vivo and in vitro. Furthermore, the anti-TNF agent etanercept is effective in the treatment of rheumatoid arthritis but failed to induce clinical response in Crohn’s disease patients, suggesting different contributions of TNF in the pathogenesis of these inflammatory diseases. In the following, we will review different aspects regarding the mechanism of action of anti-TNF agents in general and analyze comparatively different effects of each anti-TNF agent such as TNF neutralization, modulation of the immune system, reverse signaling and induction of apoptosis. We discuss the relevance of the membrane-bound form of TNF compared to the soluble form for the immunopathogenesis of IBD. Furthermore, we review reports that could lead to personalized medicine approaches regarding treatment with anti-TNF antibodies in chronic intestinal inflammation, by predicting response to therapy.

MRI texture analysis parameters of contrast-enhanced T1-weighted images of Crohn's disease differ according to the presence or absence of histological markers of hypoxia and angiogenesis

Purpose

To investigate if texture analysis parameters of contrast-enhanced MRI differ according to the presence of histological markers of hypoxia and angiogenesis in Crohn’s disease (CD).

Methods

Seven CD patients (mean age 38 (19–75), 3 male)) undergoing ileal resection underwent 3T MR enterography including axial ultrafast spoiled gradient-echo T1 post IV gadolinium chelate. Regions of interest were placed in bowel destined for resection and registered to trans-mural histological sections (n = 28 across 7 bowel sections) via MRI of the resected specimen. Microvessel density (MVD) and staining for markers of hypoxia (HIF 1α) and angiogenesis (VEGF) were performed. Texture analysis features were derived utilizing an image filtration-histogram technique at spatial scaling factor (SSF) 0–6 mm, including mean, standard deviation, mean of positive pixels, entropy, kurtosis and skewness and compared according to the presence or absence of histological markers of hypoxia/angiogenesis using Mann–Whitney U/Kruskal–Wallis tests and with the log of MVD using simple linear regression.

Results

Mean, standard deviation and mean of positive pixels were significantly lower in sections expressing VEGF. For example at SSF 6 mm, median (inter-quartile range) of mean, standard deviation and mean of positive pixels in those with VEGF expression were 150.1 (134.7), 132.4 (49.2) and 184.0 (91.4) vs. 362.5 (150.2), 216.3 (100.1) and 416.6 (80.0) in those without (p = 0.001, p = 0.004 and p = 0.001), respectively. There was a significant association between skewness and MVD (ratio 1.97 (1.15–3.41)) at SSF = 2 mm.

Conclusions

Contrast-enhanced MRI texture analysis features significantly differ according to the presence or absence of histological markers of hypoxia and angiogenesis in CD.

The Role of the Mesentery in Crohn's Disease: The Contributions of Nerves, Vessels, Lymphatics, and Fat to the Pathogenesis and Disease Course

Crohn's disease (CD) is a complex gastrointestinal disorder involving multiple levels of cross talk between the immunological, neural, vascular, and endocrine systems. The current dominant theory in CD is based on the unidirectional axis of dysbiosis-innate immunity-adaptive immunity-mesentery-body system. Emerging clinical evidence strongly suggests that the axis be bidirectional. The morphologic and/or functional abnormalities in the mesenteric structures likely contribute to the disease progression of CD, to a less extent the disease initiation. In addition to adipocytes, mesentery contains nerves, blood vessels, lymphatics, stromal cells, and fibroblasts. By the secretion of adipokines that have endocrine functions, the mesenteric fat tissue exerts its activity in immunomodulation mainly through response to afferent signals, neuropeptides, and functional cytokines. Mesenteric nerves are involved in the pathogenesis and prognosis of CD mainly through neuropeptides. In addition to angiogenesis observed in CD, lymphatic obstruction, remodeling, and impaired contraction maybe a cause and consequence of CD. Lymphangiogenesis and angiogenesis play a concomitant role in the progress of chronic intestinal inflammation. Finally, the interaction between neuropeptides, adipokines, and vascular and lymphatic endothelia leads to adipose tissue remodeling, which makes the mesentery an active participator, not a bystander, in the disease initiation and precipitation CD. The identification of the role of mesentery, including the structure and function of mesenteric nerves, vessels, lymphatics, and fat, in the intestinal inflammation in CD has important implications in understanding its pathogenesis and clinical management.

Direct effect of infliximab on intestinal mucosa sustains mucosal healing: exploring new mechanisms of action

BACKGROUND

Infliximab is effective in inflammatory bowel disease through several mechanisms, possibly acting at the mucosal level.

AIM

To assess the role of infliximab on intestinal mucosa and whether it contributes to mucosal healing.

METHODS

Human colonic mucosal biopsies were incubated with or without infliximab. Cultured biopsies were evaluated for histological staining, CD68, CD3, E-cadherin and phospho-extracellular signal-regulated kinases (ERK) expression, and apoptosis. A scratch assay and MTT assay were performed with Caco2 cells in the presence of infliximab and/or tumour necrosis factor (TNF)-α or treated with supernatants obtained from human peripheral blood mononuclear cells or human intestinal fibroblasts treated with TNF-α and infliximab alone or in association.

RESULTS

Infliximab-treated biopsies displayed a better histological appearance, reduced inflammation with an increase of E-cadherin, phospho-ERK and apoptosis. Supernatants showed lower TNF-α, IL-17, IL-6 and IL-8 concentration, with an increase in fibroblast-growth-factor. Motility at scratch assay and proliferation at MTT assay of Caco2 cells displayed differential modulation by TNF-α and infliximab, directly or through supernatants of human intestinal fibroblasts and human peripheral blood mononuclear cells exposed to them.

CONCLUSION

Infliximab contributes to the mucosal healing process by acting directly at an intestinal mucosal level; infliximab indirectly affects epithelial cell migration and proliferation by acting on both fibroblasts and leukocytes.

Angiogenesis and Vascular Endothelial Growth Factor-A Expression Associated with Inflammation in Pediatric Crohn's Disease

BACKGROUND AND AIMS

Angiogenesis is a component of chronic inflammatory diseases including inflammatory bowel disease. Some studies describe increased angiogenesis associated with acute disease in adult Crohn's disease and ulcerative colitis, while animal models aid investigations of mechanism and pathophysiology of angiogenesis. We aim to explore the role of angiogenesis and its pathways in pediatric Crohn's disease.

METHODS

Surgical specimens were obtained from pediatric Crohn's disease (both inflamed and non-inflamed regions of ileum) and control patients. Samples were examined for inflammation, microvessel density, and molecular expression of vascular endothelial growth factor-A, platelet-derived growth factor-β, angiopoietin-1, and angiopoietin-2.

RESULTS

Angiogenesis and inflammation were increased in parallel in Crohn's disease compared to controls. We also discovered increased angiogenesis in Crohn's disease tissue that was relatively free of inflammatory disease. Vascular endothelial growth factor-A gene expression (P = 0.034) was elevated in Crohn's disease over controls, while gene expression of platelet-derived growth factor-β (P = 0.069), angiopoietin-1 (P = 0.206), and angiopoietin-2 (P = 0.082) was not significantly elevated.

CONCLUSIONS

We confirm that inflammation-associated angiogenesis is upregulated in pediatric Crohn's disease. This population also exhibits elevated mucosal angiogenesis at the surgical margin with limited inflammation. This suggests that angiogenesis is an additional pathologic characteristic to potentially identify normal mucosa and margins of surgical resection that are uninvolved with disease and, furthermore, may have implications for monitoring complete disease remission. We further identify the vascular endothelial growth factor-A pathway involvement in the disease process, which may serve as a future molecular target for anti-angiogenic therapy in inflammatory bowel disease.

Mechanisms behind efficacy of tumor necrosis factor inhibitors in inflammatory bowel diseases

Biological treatment with tumor necrosis factor (TNF) inhibitors is successful in the management of inflammatory bowel disease (IBD). All TNF inhibitors antagonize the pro-inflammatory cytokine TNF-α but with varying efficacies in IBD. The variations in efficacy probably are caused by structural differences between the agents that affect their mechanisms of action and pharmacokinetic properties. Several mechanisms have been proposed, such as modulation of the expression of pro-inflammatory mediators and a reduction in the number of activated immune cells. However, it seems that clinical efficacy is the result of a number of different mechanisms and that binding of transmembrane TNF by TNF inhibitors. Knowledge of the mechanisms of action has been obtained mainly through the use of in vitro assays that may differ significantly from the situation in vivo. This review discusses the available data on TNF inhibitors in order to identify mechanisms of importance for their efficacy in IBD. Thus, a better understanding of the mechanistic basis for clinical efficacy can lead to a more rational use of TNF inhibitors in the management of IBD.

Angiogenesis in Inflammatory Bowel Disease

Angiogenesis is an important component of pathogenesis of inflammatory bowel disease (IBD). Chronic inflammation and angiogenesis are two closely related processes. Chronic intestinal inflammation is dependent on angiogenesis and this angiogenesis is modulated by immune system in IBD. Angiogenesis is a very complex process which includes multiple cell types, growth factors, cytokines, adhesion molecules, and signal transduction. Lymphangiogenesis is a new research area in the pathogenesis of IBD. While angiogenesis supports inflammation via leukocyte migration, carrying oxygen and nutrients, on the other hand, it has a major role in wound healing. Angiogenic molecules look like perfect targets for the treatment of IBD, but they have risk for serious side effects because of their nature.

Development of a Recombinant Xenogeneic Tumor Necrosis Factor Alpha Protein Vaccine To Protect Mice from Experimental Colitis

Previous studies have highlighted the efficacy of tumor necrosis factor alpha (TNF-α) inhibitors, including monoclonal antibodies and soluble receptors, in the treatment and management of intestinal bowel disease (IBD). However, because of the immunogenicity of xenogeneic TNF-α inhibitors, antidrug antibodies (ADAs) can be triggered after repeated administration. An alternative way to target TNF-α is active immunization to elicit the production of high titers of neutralizing antibodies. In this study, we prepared a xenogeneic TNF-α protein vaccine and studied the protective effects in experimental colitis models. The xenogeneic TNF-α protein vaccine could overcome self-tolerance and induce TNF-α-specific neutralizing antibody. Moreover, the xenogeneic TNF-α protein vaccine could protect mice from acute and chronic colitis induced by dextran sodium sulfate (DSS). One possible explanation for this protective effect is the production of TNF-α-specific neutralizing antibody, which absorbed the biological activity of mouse TNF-α (mTNF-α) and failed to induce T lymphocyte apoptosis. In summary, use of the xenogeneic TNF-α protein vaccine may be a potent therapeutic strategy for IBD.

Changes in dynamic contrast-enhanced pharmacokinetic and diffusion-weighted imaging parameters reflect response to anti-TNF therapy in Crohn's disease

OBJECTIVE

To investigate the effect of tumour necrosis factor (TNF)-α antagonists on MRI dynamic contrast-enhanced (DCE) and diffusion-weighted imaging (DWI) parameters in Crohn's disease (CD).

METHODS

42 patients with CD (median age 24 years; 22 females) commencing anti-TNF-α therapy with baseline and follow-up (median 51 weeks) 1.5-T MR enterography (MRE) were retrospectively identified. MRE included DCE (n = 20) and/or multi-b-value DWI (n = 17). Slope of enhancement (SoE), maximum enhancement (ME), area under the time-intensity curve (AUC), Ktrans (transfer constant), ve (fractional volume of the extravascular-extracellular space), apparent diffusion coefficient (ADC) and ADCfast/slow were derived from the most inflamed bowel segments. A physician global assessment of disease activity (remission, mild, moderate and severe) at the time of MRE was assigned, and the cohort was divided into responders and non-responders. Data were compared using Mann-Whitney U test and analysis of variance.

RESULTS

Follow-up Ktrans, ME, SoE, AUC and ADCME changed significantly in clinical responders but not in non-responders, baseline {[median [interquartile range (IQR)]: 0.42 (0.38), 1.24 (0.52), 0.18 (0.17), 17.68 (4.70) and 1.56 mm(2) s(-1) (0.39 mm(2) s(-1)) vs follow-up [median (IQR): 0.15 (0.22), 0.50 (0.54), 0.07 (0.1), 14.73 (2.06) and 2.14 mm(2) s(-1) (0.62 mm(2) s(-1)), for responders, respectively, p = 0.006 to p = 0.037}. SoE was higher and ME and AUC lower for patients in remission than for those with severe activity [mean (standard deviation): 0.55 (0.46), 0.49 (0.28), 14.32 (1.32)] vs [0.32 (0.37), 2.21 (2.43) and 23.05 (13.66), respectively p = 0.017 to 0.033]. ADC was significantly higher for patients in remission [2.34 mm(2) s(-1) (0.67 mm(2) s(-1))] than for those with moderate [1.59 mm(2) s(-1) (0.26 mm(2) s(-1))] (p = 0.005) and severe disease [1.63 mm(2) s(-1) (0.21 mm(2) s(-1))] (p = 0.038).

CONCLUSION

DCE and DWI parameters change significantly in responders to TNF-α antagonists and are significantly different according to clinically defined disease activity status.

ADVANCES IN KNOWLEDGE

DCE and DWI parameters change significantly in responders to TNF-α antagonists in CD, suggesting an effect on bowel wall vascularity.

Nitric oxide interferes with hypoxia signaling during colonic inflammation

CONTEXT

Intestinal inflammation can induce a local reduction in oxygen levels that triggers an adaptive response centered on the expression of hypoxia-inducible factors (HIFs). Nitric oxide, a well-described inflammatory mediator, may interfere with hypoxia signaling.

OBJECTIVES

We aimed to evaluate the role of nitric oxide in hypoxia signaling during colonic inflammation.

METHODS

Colitis was induced by single (acute) or repeated (reactivated colitis) trinitrobenzenosulfonic acid administration in rats. In addition, one group of rats with reactivated colitis was also treated with Nw-Nitro-L-arginine methyl ester hydrochloride to block nitric oxide synthase. Colitis was assessed by macroscopic score and myeloperoxidase activity in the colon samples. Hypoxia was determined using the oxygen-dependent probe, pimonidazole. The expression of HIF-1α and HIF-induced factors (vascular endothelial growth factor - VEGF and apelin) was assessed using Western blotting.

RESULTS

The single or repeated administration of trinitrobenzenosulfonic acid to rats induced colitis which was characterized by a high macroscopic score and myeloperoxidase activity. Hypoxia was observed with both protocols. During acute colitis, HIF-1α expression was not increased, but VEGF and apelin were increased. HIF-1α expression was inhibited during reactivated colitis, and VEGF and apelin were not increased. Nw-Nitro-L-arginine methyl ester hydrochloride blockade during reactivated colitis restored HIF-1α, VEGF and apelin expression.

CONCLUSIONS

Nitric oxide could interfere with hypoxia signaling during reactivated colitis inflammation modifying the expression of proteins regulated by HIF-1α.

Anti-angiogenic therapeutic strategies in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplastic disorder, characterized by recurrent nosebleeds (epistaxis), multiple telangiectases and arteriovenous malformations (AVMs) in major organs. Mutations in Endoglin (ENG or CD105) and Activin receptor-like kinase 1 (ACVRL1 or ALK1) genes of the TGF-β superfamily receptors are responsible for HHT1 and HHT2 respectively and account for the majority of HHT cases. Haploinsufficiency in ENG and ALK1 is recognized at the underlying cause of HHT. However, the mechanisms responsible for the predisposition to and generation of AVMs, the hallmark of this disease, are poorly understood. Recent data suggest that dysregulated angiogenesis contributes to the pathogenesis of HHT and that the vascular endothelial growth factor, VEGF, may be implicated in this disease, by modulating the angiogenic–angiostatic balance in the affected tissues. Hence, anti-angiogenic therapies that target the abnormal vessels and restore the angiogenic–angiostatic balance are candidates for treatment of HHT. Here we review the experimental evidence for dysregulated angiogenesis in HHT, the anti-angiogenic therapeutic strategies used in animal models and some patients with HHT and the potential benefit of the anti-angiogenic treatment for ameliorating this severe, progressive vascular disease.

Long-term risk of mesenteric ischemia in patients with inflammatory bowel disease: a 13-year nationwide cohort study in an Asian population

BACKGROUND

It is unclear whether patients with inflammatory bowel disease (IBD) have higher risks of developing mesenteric ischemia.

METHODS

We enrolled 9,363 patients who had been hospitalized because of IBD between January 1998 and December 2010, along with 37,452 control patients who were matched at a 1:4 proportion for age, sex, and index year. We accounted the cumulative incidences and hazard ratios (HRs) of developing mesenteric ischemia during the 13-year study period.

RESULTS

Patients with IBD had a considerably higher incidence rate of subsequent mesenteric ischemia compared with the controls (22.7 vs 3.09 per 10,000 person-years), with adjusted HR of 6.33 (95% confidence interval: 4.75 to 8.43). A multivariate stratified analysis showed that the mesenteric ischemia risk after adjustment for comorbidities is significantly higher in patients of all age groups, particularly in patients younger than 44 years (adjusted HR: 48.0; 95% confidence interval: 11.3 to 203.9). Moreover, patients with IBD were at highest risk of developing mesenteric ischemia within the first year of follow-up.

CONCLUSIONS

Careful follow-up and effective therapy are necessary to reduce the excessive risk in these patients.

The neurotensin-HIF-1α-VEGFα axis orchestrates hypoxia, colonic inflammation, and intestinal angiogenesis

The expression of neurotensin (NT) and its receptor (NTR1) is up-regulated in experimental colitis and inflammatory bowel disease; NT/NTR1 interactions regulate gut inflammation. During active inflammation, metabolic shifts toward hypoxia lead to the activation of hypoxia-inducible factor (HIF)-1, which enhances vascular endothelial growth factor (VEGF) expression, promoting angiogenesis. We hypothesized that NT/NTR1 signaling regulates intestinal manifestations of hypoxia and angiogenesis by promoting HIF-1 transcriptional activity and VEGFα expression in experimental colitis. We studied NTR1 signaling in colitis-associated angiogenesis using 2,4,6-trinitrobenzenesulfonic acid-treated wild-type and NTR1-knockout mice. The effects of NT on HIF-1α and VEGFα were assessed on human colonic epithelial cells overexpressing NTR1 (NCM460-NTR1) and human intestinal microvascular-endothelial cells. NTR1-knockout mice had reduced microvascular density and mucosal integrity score compared with wild-type mice after 2,4,6-trinitrobenzenesulfonic acid treatment. VEGFα mRNA levels were increased in NCM460-NTR1 cells treated with 10(-7) mol/L NT, at 1 and 6 hours post-treatment. NT exposure in NCM460-NTR1 cells caused stabilization, nuclear translocation, and transcriptional activity of HIF-1α in a diacylglycerol kinase-dependent manner. NT did not stimulate tube formation in isolated human intestinal macrovascular endothelial cells but did so in human intestinal macrovascular endothelial cells cocultured with NCM460-NTR1 cells. Our results demonstrate the importance of an NTR1-HIF-1α-VEGFα axis in intestinal angiogenic responses and in the pathophysiology of colitis and inflammatory bowel disease.

Enhanced apoptosis of monocytes from complication-free juvenile-onset diabetes mellitus type 1 may be ameliorated by TNF-α inhibitors

Diabetes mellitus type 1 is associated with an enhanced apoptosis of different cells and tissues, accelerating occurrence of diabetic microvascular complications. The aim of our study was to determine spontaneous apoptotic potential of the monocyte subsets in juvenile-onset complication-free diabetes mellitus type 1 and to compare them with the corresponding values of the healthy. Moreover, we wanted to assess effects of TNF-R1 blocking agents and those of general TNF-α blocker (Infliximab) on spontaneous apoptosis of monocytes. Sixty randomly selected DM1 patients (14.5 ± 3.2 years) and 30 healthy (13.5 ± 2.8 years) volunteers were enrolled in the study. Our results indicate that three monocyte subsets are distinguishable in the groups of young diabetic patients and the healthy, similarly to in the blood of adults. DM1 patients were characterized by higher values of apoptotic monocytes than the healthy. The manipulation with drugs inhibiting TNF-R1 expression diminished the pool of CD16(+) apoptotic monocytes. Infliximab reduced the apoptotic CD16(-) cells. In conclusion, diabetes mellitus type 1 is associated with greater apoptosis of three monocyte subsets which may contribute to the development of microvascular complications. TNF-α modifiers appear to ameliorate monocyte apoptosis. They may be useful for controlling excessive monocyte apoptosis in diabetic patients.

The effects of infliximab or adalimumab on vascular endothelial growth factor and angiopoietin 1 angiogenic factor levels in inflammatory bowel disease: serial observations in 37 patients

BACKGROUND

Infliximab and adalimumab effectiveness might be related with changes in angiogenic factors. The aim of the study was to compare the concentrations of angiogenic proteins in patients with inflammatory bowel disease (IBD) and healthy controls and to analyze changes in the levels during infliximab and adalimumab treatment.

METHODS

A prospective case-control study was conducted in 37 patients with IBD starting treatment with infliximab (16 with Crohn's disease and 6 with ulcerative colitis) or adalimumab (15 with Crohn's disease) and 40 control subjects. Four samples were taken from IBD patients, one before each of the first 3 doses of infliximab/adalimumab and one at week 14. Serum levels of vascular endothelial growth factor (VEGF), placental growth factor, angiopoietin 1 (Ang1), angiopoietin 2, and Tie2 were measured using enzyme-linked immunosorbent assay.

RESULTS

Patients with IBD had higher VEGF levels than control subjects (511.5 ± 255.6 versus 395.5 ± 256.4; P = 0.05). Patients who achieved remission at the third dose of anti-TNF-alpha had lower VEGF levels at baseline (453.5 ± 250.7 versus 667.5 ± 153.9 pg/mL) and before the second (409.7 ± 217 versus 681.3 ± 350.6 pg/mL) and third (400.5 ± 222.8 versus 630.4 ± 243.1 pg/mL) doses compared with those with no remission (P < 0.05). Ang1 levels decreased before each treatment dose in patients who achieved remission (P < 0.05). High baseline VEGF levels predicted for a poor response to anti-TNF-alpha therapy (area under the receiver operating characteristics curve = 0.8), whereas high Ang1 levels were associated with disease remission (area under the receiver operating characteristics curve = 0.7). Concentrations of angiogenic proteins did not correlate with clinical activity scores.

CONCLUSIONS

Circulating VEGF and Ang1 levels decrease after anti-TNF-alpha therapy and may predict response to treatment. Whether these changes are a direct effect of anti-TNF-alpha therapy or a sign of disease improvement remains to be elucidated.

The potential role of angiogenic factors in rheumatoid arthritis

Angiogenesis is an important phenomenon in the pathogenesis of some diseases, such as numerous types of tumors and autoimmunity, and also a number of soluble and cell-bound factors may stimulate neovascularization in inflammatory reaction processes. Here, by highlighting the significance of angiogenesis reaction in rheumatoid arthritis (RA), we will mainly focus on the role of various growth factors, cytokines, enzymes, cells, hypoxic conditions and transcription factors in the angiogenic process and we will then explain some therapeutic strategies based on blockage of angiogenesis and modification of the vascular pathology in RA.

Therapeutic effects of diammonium glycyrrhizinate combined with safflower solution on ulcerative colitis in rats

AIM: To evaluate the therapeutic effects of diammonium glycyrrhizinate (DG) combined with safflower solution (SS) on experimental colitis and on the expression of interleukin-8 (IL-8) in rats.

METHODS: Forty Sprague-Dawley rats were randomized into a normal control group, a treatment group (DG combined with SS), a DG group and a TNBS control group, with 10 rats in each group. Colitis was induced by rectal administration of TNBS in rats in the treatment group, DG group and TNBS control group. Rats in the treatment group were treated with DG (40 mg/kg) and SS (400 mg/kg) every day, and the DG group was treated with DG (40 mg/kg) every day. Disease activity index (DAI) and histological damage score were calculated, and the expression of IL-8 in colon tissues was detected by immunohistochemistry.

RESULTS: In the normal control group, treatment group, DG group and TNBS control group, DAIs were 1.4 ± 0.3, 2.4 ± 0.2, 3.8 ± 0.4 and 7.6 ± 0.9, respectively; histological damage scores were 1.5 ± 0.4, 2.4 ± 0.4, 3.7 ± 0.6 and 6.3 ± 1.1, respectively; and the positive percentages of IL-8 were 15.7% ± 3.7%, 20.8% ± 4.7%, 34.7% ± 4.9% and 56.4% ± 6.9%, respectively. Compared with the TNBS control group, DAI and histological injury scores were significantly improved in the treatment group and DG group, and the expression of IL-8 was decreased significantly in the treatment group (P < 0.01 or < 0.05). Compared with the DG group, DAI and histological damage scores were significantly improved and the expression of IL-8 was decreased significantly in the treatment group (P < 0.01 or < 0.05).

CONCLUSION: DG combined with SS exerts a better effect than DG alone in the treatment of experimental ulcerative colitis in rats, and the underlying mechanism is possibly associated with affecting the expression of IL-8.

Advances in therapeutic interventions targeting the vascular and lymphatic endothelium in inflammatory bowel disease

PURPOSE OF REVIEW

The review summarizes the current knowledge of the roles played by the vascular and lymphatic endothelium throughout the gut in the pathogenesis of inflammatory bowel disease (IBD) and gives an update on emerging strategies targeting both vasculatures.

RECENT FINDINGS

Enormous efforts have been made to understand the mechanisms underlining the origin, development and maintenance of intestinal chronic inflammation. In particular, new studies focused their attention on the role played by the microvascular and lymphatic endothelium in the pathogenesis of IBD. During inflammation, whereas the microvasculature is responsible for the entry and distribution of immune cells in the mucosa, the lymphatic system controls leukocyte exit, bacterial clearance and edema absorption. The study of these events, which are aberrant during chronic inflammation, has resulted in the identification and validation of several targets for the treatment of experimental colitis, some of which have translated into effective treatments for patients with IBD.

SUMMARY

Although much attention has been paid to the microvascular endothelium and to antiangiogenic therapies, specific studies on the lymphatic vasculature and its functions in IBD are still at the initial stage, and other molecular mechanisms, genes, molecules and new pathways must definitely be explored.

Leukocyte traffic control: a novel therapeutic strategy for inflammatory bowel disease--an update

Adhesion molecules play a key role in the pathogenetic mechanisms of inflammatory bowel disease (IBD), both in Crohn's disease (CD) and ulcerative colitis (UC). In the last decade, some progress has been made in understanding their key role in leukocyte trafficking control in terms of basic research, but evidence of clinical efficacy is lacking. In the last 2 years, new molecules directed against integrins and integrin receptors have been developed and investigated in clinical trials, showing that anti-α4β7 integrin agents can be effective and safe for the induction and maintenance of remission in active CD and UC. Preliminary data show that anti-MAdCAM, anti-β7 and anti-integrin receptor agents are not all effective in IBD. Such results open new perspectives on clinical management of IBD, and new directions in understanding the role of adhesion molecules and leukocyte recruitment both in CD and UC.

The proto-oncogene c-Fos transcriptionally regulates VEGF production during peritoneal inflammation

Vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) are key mediators of adverse peritoneal membrane remodeling in peritoneal dialysis eventually leading to ultrafiltration failure. Both are pleiotropic growth factors with cell type-dependent regulation of expression and biological effects. Here we studied regulation of TGF-β1-induced VEGF expression in human peritoneal mesothelial cells in the absence or presence of proinflammatory stimuli, tumor necrosis factor-α (TNF-α) or interleukin-1β (IL-1β). Quiescent human peritoneal mesothelial cells secreted only trace amounts of VEGF. Stimulation with TGF-β1 resulted in time- and dose-dependent increases in VEGF mRNA expression and protein release. TNF-α and IL-1β alone had minimal effects but acted in synergy with TGF-β1. Combined stimulation led to induction of transcription factor c-Fos and activation of the VEGF promoter region with high-affinity binding sites for c-Fos. Inhibition of c-Fos by small interfering RNA interference or by pharmacological blockade with SR-11302 decreased VEGF promoter activity and downregulated its expression and release. Exposure of human peritoneal mesothelial cells to dialysate effluent containing increased levels of TGF-β1, TNF-α, and IL-1β obtained during peritonitis resulted in a dose-dependent VEGF induction that was significantly attenuated by SR-11302. Thus, dialysate TGF-β1, IL-1β, and TNF-α act through c-Fos to synergistically upregulate VEGF production in peritoneal mesothelium and may represent an important regulatory link between inflammation and angiogenesis in the peritoneal membrane.

Mechanisms of action of anti-tumor necrosis factor α agents in Crohn's disease

Crohn's disease (CD) is characterized by inflammation that can affect any part of the gastrointestinal tract. It is a chronic destructive condition that follows a relapsing-remitting course and can lead to disability and a poor quality of life. Lifelong pharmacotherapy with systemic immunomodulator therapies remains the cornerstone of CD management. Advances in understanding of the immunopathogenic mechanisms underlying chronic gut inflammation in CD have led to the development of effective biological therapies for patients with CD. Tumor necrosis factor α (TNF-α) is a potent proinflammatory cytokine that plays a pivotal role in the development of Crohn's inflammation. Therapies designed to target this cytokine have revolutionized treatment of CD since their introduction in the late 1990s, thanks to their ability to induce and maintain remission, heal mucosa, reduce hospital admissions and surgical procedures, and restore quality of life. Despite widespread use of these therapies in CD, their precise mechanism of action remains unclear, although several different mechanisms have been proposed. This review summarizes the biology of the TNF-α cytokine and the development of biological therapies targeting TNF-α, and updates our current understanding of mechanisms of action of the commercially available anti-TNF-α therapies used in the treatment of CD.

Vascular endothelial growth factor receptor-2 inhibition in experimental murine colitis

BACKGROUND

In the setting of inflammatory bowel disease, inflammation is associated with a simultaneous increase in angiogenesis; moreover, elevated vascular endothelial growth factor (VEGF) levels implicate angiogenesis as a pathologic contributor to disease severity. We hypothesize that selectively inhibiting vascular endothelial growth factor receptor-2 (VEGFR2) in a model of murine colitis will reduce angiogenesis, resulting in decreased inflammation and disease severity, providing mechanistic insight into the role of pathologic angiogenesis in IBD.

MATERIALS AND METHODS

In a dextran sodium sulfate model of murine colitis, anti-VEGFR2 monoclonal antibody (DC101) or placebo was administered. Clinical assessments followed by histologic and molecular tissue analysis were performed to quantify inflammation, microvessel density (MVD), VEGF and VEGFR2 gene expression, and phosphorylated mitogen-activated protein kinase protein expression.

RESULTS

Weight loss began after d 6 with the treatment group demonstrating a more favorable percent weight change. Inflammation and MVD were similar between cohorts, both increasing in parallel toward a plateau. VEGF and VEGFR2 messenger RNA expression were not significantly different, but phosphorylated mitogen-activated protein kinase was elevated in the DC101 cohort (P = 0.03).

CONCLUSIONS

Despite a more favorable weight change profile in the treated group, no difference was observed between cohorts regarding clinical disease severity. However, a parallel rise in inflammation and MVD was observed coinciding with weight loss, suggesting their relationship in IBD. VEGFR2 downstream signaling was significantly elevated in the treated cohort, possibly by VEGF-independent signal transduction. Early and effective inhibition of angiogenesis by limiting downstream VEGF signaling or targeting multiple angiogenic pathways may block angiogenesis, thereby reducing disease severity and provide evidence toward the mechanism and clinical benefit of antiangiogenics in the setting of IBD.

Effect of treatment with safflower solution on expression of VEGF and bFGF in ulcerative colitis in rats

AIM: To evaluate the therapeutic effect of safflower solution on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced ulcerative colitis in rats and to explore the underlying mechanisms by observing the expression of vascular endothelial growth factor (VEGF) and basal fibroblast growth factor (bFGF).

METHODS: Thirty Wistar rats were randomly divided into normal control group, model group and safflower group. Ulcerative colitis was induced in the safflower group and model group with TNBS by enema. Rats of the safflower group were intraperitoneally injected with safflower solution. After ten days, all rats were killed. Disease activity index (DAI), colon macroscopic damage score (CMDS) and histological damage score were evaluated. Pathological changes in the colonic mucosa were examined by HE staining. The expression of VEGF and bFGF in the colonic mucosa was detected by real time-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC).

RESULTS: Compared to normal controls, the DAI, CMDS and histological damage scores in model rats were significantly increased (all P < 0.01). Compared to the model group, the above parameters were significantly improved in the safflower group (all P < 0.05). Compared to normal controls, the expression levels of VEGF and bFGF in model rats were increased significantly (all P < 0.01). Treatment with safflower solution significantly decreased the expression levels of VEGF mRNA and protein in ulcerative colitis (both P < 0.05).

CONCLUSION: Treatment with safflower solution could reduce inflammatory injury in a rat model of ulcerative colitis possibly by reducing the expression of VEGF and inhibiting pathologic angiogenesis in the colonic mucosa.

Integrated models of care in managing inflammatory bowel disease: a discussion

The World Health Organization has recommended the integrated model of care as the current best practice of care, and, in recent years, it has been gaining popularity worldwide in various settings. However, there have been very few reports on applications of this model to the care of patients with gastrointestinal problems and no reports in the case of inflammatory bowel disease (IBD). However, several IBD centres worldwide have been using the model as part of their standard care. This discussion paper aims to bring together these units' shared experiences with a range of integrated models of care in order to identify common features and provide recommendations on aspirational care for IBD patients.

Expansion of CD14+CD16+ monocytes producing TNF-α in complication-free diabetes type 1 juvenile onset patients

We concentrated on the complication-free phase of juvenile onset type 1 diabetes mellitus (T1DM) searching for associations between concentration of inflammatory factors TNF-α, CRP and VEGF and two monocyte subsets the CD14(++)CD16(-) and CD14(+)CD16(+). We analysed a randomly selected group of 150 patients without complications (disease duration 2.74 ± 2.51 years) at the start of the project and 5 years later. They were compared with 24 patients with retinopathy (6.53 ± 3.39 years of disease) and 30 healthy volunteers. Our results indicate that in the complication-free period the concentration of TNF-α significantly increased and continued to increase after retinopathy was established. After 5 years the percentage and absolute number of CD14(+)CD16(+) monocytes doubled in complication-free patients. Our study indicates that the size of CD14(+)CD16(+) monocyte subset may be used alternatively to CRP values as an indicator of inflammation grade. Our results imply the necessity of trials using anti-TNF-α therapy in the complication-free phase of the disease.

Pretreatment with anti-VEGF therapy may exacerbate inflammation in experimental acute colitis

AIM

Our previous investigations of angiogenesis in inflammatory bowel disease showed that vascular endothelial growth factor (VEGF) blockade reduced colonic neovascularization and inflammation. We hypothesized that pretreatment with bevacizumab, a monoclonal anti-VEGF antibody, would attenuate the severity of angiogenesis and inflammation in a murine model of colitis.

METHODS

C57BL/6 mice were treated with intraperitoneal injections of bevacizumab (250 μg/dose) before induction of colitis with dextran sulfate sodium (DSS). The colons were examined at predetermined time points. Colonic inflammation and microvessel density were assessed microscopically.

RESULTS

All mice acutely developed melena and weight loss (18.8% ± 1.1% control vs 20.2% ± 1.1% treated, P = .37) and regained a similar weight percentage after the recovery (26.5% ± 4.0% vs 20.9% ± 4.4%, P = .37). Microvessel density acutely increased in both groups in response to DSS, with a trend toward inhibited angiogenesis in the treated group at the conclusion of the acute phase (194,100 ± 14,240 vs 149,400 ± 17,590 μm(2), P = .11). Bevacizumab-treated mice exhibited significantly increased inflammation after the acute phase (8.3 ± 0.8 vs 13.0 ± 2.0, P = .05), but were similar to control after the recovery (7.3 ± 1.5 vs 5.5 ± 1.0, P = .27).

CONCLUSIONS

Preemptive VEGF inhibition does not significantly attenuate angiogenesis and, in fact, worsens inflammation in a model of acute colitis. Preventive VEGF blockade may disrupt healing and exacerbate injury via alternative angiogenic or inflammatory pathways.

Anti-TNF-alpha therapy enhances the effects of enzyme replacement therapy in rats with mucopolysaccharidosis type VI

Background

Although enzyme replacement therapy (ERT) is available for several lysosomal storage disorders, the benefit of this treatment to the skeletal system is very limited. Our previous work has shown the importance of the Toll-like receptor 4/TNF-alpha inflammatory pathway in the skeletal pathology of the mucopolysaccharidoses (MPS), and we therefore undertook a study to examine the additive benefit of combining anti-TNF-alpha therapy with ERT in a rat model of MPS type VI.

Methodology/Principal Findings

MPS VI rats were treated for 8 months with Naglazyme® (recombinant human N-acetyl-galactosamine-4-sulfatase), or by a combined protocol using Naglazyme® and the rat-specific anti-TNF-alpha drug, CNTO1081. Both protocols led to markedly reduced serum levels of TNF-alpha and RANKL, although only the combined treatment reduced TNF-alpha in the articular cartilage. Analysis of cultured articular chondrocytes showed that the combination therapy also restored collagen IIA1 expression, and reduced expression of the apoptotic marker, PARP. Motor activity and mobility were improved by ERT, and these were significantly enhanced by combination treatment. Tracheal deformities in the MPS VI animals were only improved by combination therapy, and there was a modest improvement in bone length. Ceramide levels in the trachea also were markedly reduced. MicroCT analysis did not demonstrate any significant positive effects on bone microarchitecture from either treatment, nor was there histological improvement in the bone growth plates.

Conclusions/Significance

The results demonstrate that combining ERT with anti-TNF- alpha therapy improved the treatment outcome and led to significant clinical benefit. They also further validate the usefulness of TNF-alpha, RANKL and other inflammatory molecules as biomarkers for the MPS disorders. Further evaluation of this combination approach in other MPS animal models and patients is warranted.