Meta-analysis using individual patient data: efficacy and durability of topical alicaforsen for the treatment of active ulcerative colitis

Recruitment and Residence of Intestinal T Cells - Lessons for Therapy in Inflammatory Bowel Disease

Targeting leukocyte trafficking in the management of inflammatory bowel disease [IBD] has been a significant therapeutic advance over the past 15 years. However, as with other advanced therapies, phase III clinical trials report response to trafficking inhibitors in only a proportion of patients, with fewer achieving clinical remission or mucosal healing. Additionally, there have been significant side effects, most notably progressive multifocal leukoencephalopathy in association with the α4 inhibitor natalizumab. This article reviews the mechanisms underpinning T cell recruitment and residence, to provide a background from which the strength and limitations of agents that disrupt leukocyte trafficking can be further explored. The therapeutic impact of trafficking inhibitors is underpinned by the complexity and plasticity of the intestinal immune response. Pathways essential for gut homing in health may be bypassed in the inflamed gut, thus providing alternative routes of entry when conventional homing molecules are targeted. Furthermore, there is conservation of trafficking architecture between proinflammatory and regulatory T cells. The persistence of resident memory cells within the gut gives rise to local established pro-inflammatory populations, uninfluenced by inhibition of trafficking. Finally, trafficking inhibitors may give rise to effects beyond the intended response, such as the impact of vedolizumab on innate immunity, as well as on target side effects. With significant research efforts into predictive biomarkers already underway, it is ultimately hoped that a better understanding of trafficking and residence will help us predict which patients are most likely to respond to inhibition of leukocyte trafficking, and how best to combine therapies.

MicroRNA-based therapeutics for inflammatory disorders of the microbiota-gut-brain axis

An emerging but less explored shared pathophysiology across microbiota-gut-brain axis disorders is aberrant miRNA expression, which may represent novel therapeutic targets. miRNAs are small, endogenous non-coding RNAs that are important transcriptional repressors of gene expression. Most importantly, they regulate the integrity of the intestinal epithelial and blood-brain barriers and serve as an important communication channel between the gut microbiome and the host. A well-defined understanding of the mode of action, therapeutic strategies and delivery mechanisms of miRNAs is pivotal in translating the clinical applications of miRNA-based therapeutics. Accumulating evidence links disorders of the microbiota-gut-brain axis with a compromised gut-blood-brain-barrier, causing gut contents such as immune cells and microbiota to enter the bloodstream leading to low-grade systemic inflammation. This has the potential to affect all organs, including the brain, causing central inflammation and the development of neurodegenerative and neuropsychiatric diseases. In this review, we have examined in detail miRNA biogenesis, strategies for therapeutic application, delivery mechanisms, as well as their pathophysiology and clinical applications in inflammatory gut-brain disorders. The research data in this review was drawn from the following databases: PubMed, Google Scholar, and Clinicaltrials.gov. With increasing evidence of the pathophysiological importance for miRNAs in microbiota-gut-brain axis disorders, therapeutic targeting of cross-regulated miRNAs in these disorders displays potentially transformative and translational potential. Further preclinical research and human clinical trials are required to further advance this area of research.

The Roles of Cardiac Fibroblasts and Endothelial Cells in Myocarditis

In myocarditis caused by various etiologies, activated immune cells and the immune regulatory factors released by them play important roles. But in this complex microenvironment, non-immune cells and non-cardiomyocytes in the heart, such as cardiomyocytes (CMs), cardiac fibroblasts (CFs) and endothelial cells (ECs), play the role of “sentinel”, amplify inflammation, and interact with the cardiomyocytes. The complex interactions between them are rarely paid attention to. This review will re-examine the functions of CFs and ECs in the pathological conditions of myocarditis and their direct and indirect interactions with CMs, in order to have a more comprehensive understanding of the pathogenesis of myocarditis and better guide the drug development and clinical treatment of myocarditis.

When disease extent is not always a key parameter: Management of refractory ulcerative proctitis

Background

Patients with ulcerative proctitis represent a sub-group of ulcerative colitis patients with specific characteristics. Disease-related symptoms, endoscopic findings and patient's personality perspectives create a difficult-to-assess condition in certain cases.

Objectives

To summarize available evidence on the management of refractory ulcerative proctitis and provide insights in treatment options.

Results

/Conclusion: Topical therapy plays a central role due to the location of the disease. However, well-established treatment options may become exhausted in a considerable proportion of ulcerative proctitis patients, indicating the need to advance to more potent therapies in order to induce and maintain clinical response and remission in these refractory cases. Systemic corticosteroids, thiopurines, calcineurin inhibitors, biologic agents and small molecules have all been tested with variable success rates. Investigational interventions as well as surgical procedures are kept as the ultimate resort in multi-treatment resistant cases. Identifying early prognostic factors that herald a disabling disease progression will help in optimizing treatment and avoiding surgery.

Immunohistochemical Study of Adhesion Molecules in Irritable Bowel Syndrome: A Comparison to Inflammatory Bowel Diseases

Background:

The surface of endothelial cells is covered with cell adhesion molecules including E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) that mediate the adhesion and extravasation of leukocytes and play a pivotal role in inflammatory response. The aim of this study was to investigate the role of expression of adhesion molecules in inflammatory bowel disease (IBD) patients, irritable bowel syndrome (IBS) patients, and normal colonic mucosa.

Materials and Methods:

IBS and IBD patients along with normal colonic mucosa were recruited in the study. In all groups, two biopsies were taken from each of the three anatomical sites (terminal ileum, cecum, and rectum). Three monoclonal antibodies, E-selectin mAb, VCAM-1 mAb, and ICAM-1 mAb, were applied for immunohistochemical analysis.

Results:

In IBD patients, the expression of intensity of E-selectin, VCAM-1, and ICAM-1 was found decreased, at least in cecum and rectum, in comparison with IBS patients and controls (P < 0.001, P < 0.005, and P < 0.007, respectively). Comparison of the expression of intensity of the aforementioned molecules in IBS patients and controls revealed significant augmentation at the cecum and rectum of IBS patients.

Conclusions:

The expression of adhesion molecules appeared lower in IBD patients compared to IBS patients and controls. In addition, the expression of adhesion molecules appeared higher in IBS compared to the control group. Therefore, it could be hypothesized that the expression of adhesion molecules could be considered as an early event in the process of proinflammatory IBS group and may be other factors play a crucial role in the process of intestinal inflammation in IBD patients.

Current Strategies and Potential Prospects of Nanomedicine-Mediated Therapy in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) such as Crohn's disease and ulcerative colitis are highly debilitating. IBDs are associated with the imbalance of inflammatory mediators within the inflamed bowel. Conventional drugs for IBD treatment include anti-inflammatory medications and immune suppressants. However, they suffer from a lack of bioavailability and high dose-induced systemic side effects. Nanoparticle (NP)-derived therapy improves therapeutic efficacy and increases targeting specificity. Recent studies have shown that nanomedicines, based on bowel disease's pathophysiology, are a fast-growing field. NPs can prolong the circulation period and reduce side effects by improving drug encapsulation and targeted delivery. Here, this review summarizes various IBD therapies with a focus on NP-derived applications, whereas their challenges and future perspectives have also been discussed.

Oligonucleotides-A Novel Promising Therapeutic Option for IBD

Inflammatory Bowel Diseases (IBD), whose denomination comprehends Crohn's Disease (CD) and Ulcerative Colitis (UC), are intestinal chronic diseases that often require lifelong medical therapy. In the last two decades monoclonal antibodies against the cytokine TNF have become integral parts in the treatment of IBD patients, however there are unwanted side-effects and one third of patients show primary non-response while another subgroup loses response over time. Finding novel drugs which could act as therapies against precise pro-inflammatory molecular targets to avoid unwanted systemic side effects and additionally the process of immunization, represents an important aim for subsequent therapeutic approaches. Oligonucleotide based therapies represent a promising novel concept for the treatment of IBD. The molecular action of oligonucleotides ranges from inhibition of the translational process of mRNA transcripts of pro-inflammatory molecules, to mimicking bacterial DNA which can activate cellular targets for immunomodulation. Alicaforsen, selectively targets ICAM-1 mRNA. ICAM-1 is an adhesion molecule which is upregulated on endothelial cells during IBD, thereby mediating the adhesion and migration of leucocytes from blood to sites of active inflammation. In CD parenteral application of alicaforsen did not show therapeutic efficacy in phase II trials, but it demonstrated an improved efficacy as a topical enema in distal UC. Topical application of alicaforsen might represent a therapeutic perspective for refractory pouchitis as well. SMAD7 is a protein that inhibits the signaling of TGFβ, which is the mainstay of a regulatory counterpart in cellular immune responses. An antisense oligonucleotide against SMAD7 mRNA (mongersen) demonstrated pre-clinical and phase II efficacy in CD, but a phase III clinical trial was stopped due to lack of efficacy. Cobitolimod is a single strand oligonucleotide, which mimics bacterial DNA as its CpG dinucleotide sequences can be recognized by the Toll-like receptor 9 on different immune cells thereby causing induction of different cytokines, for example IL10 and IFNα. Topical application of cobitolimod was studied in UC patients. We will also discuss two other novel oligonucleotides which act on the GATA3 transcription factor (SB012) and on carbohydrate sulfotransferase 15 (STNM01), which could both represent novel promising therapeutic options for the treatment of UC.

The future of nanomedicine in optimising the treatment of inflammatory bowel disease

There have been major advancements in the treatment of inflammatory bowel disease (IBD) over the past three decades. However despite significant progress, the best available treatments continue to demonstrate variable efficacy in patients and are associated with adverse effects. Therefore there remains an unmet clinical need for ongoing therapeutic advances for IBD. In recent years nanomedicines have emerged as promising diagnostic and therapeutic tools. Nanoparticles in particular show promise to facilitate targeted oral drug delivery in IBD. Here we discuss the pitfalls of current therapies and explore the potential for nanoparticles to improve the treatment of IBD. This review examines the range of conventional and novel therapies which have benefited from nanoparticle-mediated delivery and highlights the proven therapeutic efficacy of this approach in preclinical models. These strategies under development represent a novel and innovative treatment for IBD.

Targeting Endothelial Ligands: ICAM-1/alicaforsen, MAdCAM-1

Specific blockade of the endothelial ligands intercellular adhesion molecule-1 [ICAM-1] and mucosal addressin cell adhesion molecule [MAdCAM] involved in leukocyte recruitment to the site of inflammation as therapeutic targets in inflammatory bowel disease [IBD] has been recognized from their overexpression in the inflamed mucosa and successful intervention based on these ligands in preclinical animal models. Interventions to target ICAM-1 in human IBD are confined to the ICAM-1 anti-sense oligonucleotide alicaforsen. While results with parenteral formulations of alicaforsen in Crohn's disease have largely been negative, efficacy signals derived from studies with an enema formulation in ulcerative colitis and pouchitis are promising and have led to a Food and Drug Administration Fast-Track designation for the latter. A large phase III programme in pouchitis is underway. Phase II studies with the anti-MAdCAM-1 antibody [SHP647] delivered positive results in ulcerative colitis and anti-inflammatory signals in Crohn's disease. Furthermore, it was shown that SHP647 does not affect the number and composition of cells in cerebrospinal fluid, suggesting that the compound is not affecting immune surveillance in the central nervous system. In addition, both alicaforsen and SHP647 are promising compounds based on the clear safety profile observed so far.

Immunotherapy in inflammatory bowel disease: Novel and emerging treatments

Inflammatory bowel disease (IBD) is a chronic disabling inflammatory process that affects young individuals, with growing incidence. The etiopathogenesis of IBD remains poorly understood. A combination of genetic and environmental factors triggers an inadequate immune response against the commensal intestinal flora in IBD patients. Thus, a better understanding of the immunological mechanisms involved in IBD pathogenesis is central to the development of new therapeutic options.

Current pharmacological treatments used in clinical practice like thiopurines or anti-TNF are effective but can produce significant side effects and their efficacy may diminish over time. In fact, up to one third of the patients do not have a satisfactory response to these therapies. Consequently, the search for new therapeutic strategies targeting alternative immunological pathways has intensified. Several new oral and parenteral substances are in the pipeline for IBD.

In this review we discuss novel therapies targeting alternative pro-inflammatory pathways like IL-12/23 axis, IL-6 pathway or Janus Kinase inhibitors; as well as others modulating anti-inflammatory signalling pathways like transforming growth factor-β1 (TGF-β1). We also highlight new emerging therapies targeting the adhesion and migration of leukocytes into the inflamed intestinal mucosa by blocking selectively different subunits of α₄β₇ integrins or binding alternative adhesion molecules like MAdCAM-1. Drugs reducing the circulating lymphocytes by sequestering them in secondary lymphoid organs (sphingosine-1-phosphate (S1P) receptor modulators) are also discussed. Finally, the latest advances in cell therapies using mesenchymal stem cells or engineered T regs are reviewed. In addition, we provide an update on the current status in clinical trials of these new immune-regulating therapies that open a new era in the treatment of IBD.

Similar Inhibition of Dynamic Adhesion of Lymphocytes From IBD Patients to MAdCAM-1 by Vedolizumab and Etrolizumab-s

BACKGROUND

Although anti-adhesion therapies are a novel mainstay in the treatment of inflammatory bowel diseases (IBDs), the mechanisms controlling integrin-dependent gut homing are poorly elucidated, and the available techniques for translational functional investigations are limited.

METHODS

We used dynamic adhesion assays to study adhesion of CD4+ T cells, CD8+ T cells, CD19+ B cells, and granulocytes to the addressins MAdCAM-1, VCAM-1, and ICAM-1. The effects of vedolizumab, natalizumab, etrolizumab-s, anti-CD11a, and anti-CD18 antibodies were explored.

RESULTS

Adhesion of peripheral blood leukocytes from IBD patients and control donors could be validly assessed, and integrin-mediated addressin adhesion could be specifically inhibited by anti-integrin antibodies. Numbers of adhering cells were partly, but not completely, related to integrin expression. Vedolizumab and etrolizumab-s resulted in similar reduction of adhesion to MAdCAM-1, and preliminary data proposed an association of dynamic adhesion to MAdCAM-1 with response to vedolizumab therapy.

CONCLUSIONS

Dynamic adhesion assays are an easy and broadly applicable method for IBD research that is useful for future translational studies and potentially also for supporting clinical treatment decisions. 10.1093/ibd/izy077_video1izy077_Video_15786486962001.

The treatment of refractory ulcerative colitis

Ulcerative proctitis is defined as a mucosal inflammation limited to the rectum. Ulcerative proctitis is responsible for distressing symptoms and alteration of patient quality of life. Effective treatment is important to prevent or delay proximal extension of the disease and to improve quality of life. Refractory ulcerative proctitis is defined as the failure of topical and oral 5-aminosalicylic acid and corticosteroids. Medical management of refractory ulcerative proctitis may be challenging as there is little evidence regarding drug efficacy in this clinical situation. Data are currently available for azathioprine, topical tacrolimus and anti-TNF monoclonal antibodies as rescue treatment for refractory ulcerative proctitis. Other biologics may be of benefit despite a lack of dedicated clinical trials. Ultimately, experimental therapies such as epidermal growth factor enemas, appendectomy or fecal transplantation may be tried before restorative proctocolectomy with J pouch anastomosis, which has demonstrated good results with regards to clinical remission and quality of life.

Alicaforsen, an Antisense Inhibitor of Intercellular Adhesion Molecule-1, in the Treatment for Left-Sided Ulcerative Colitis and Ulcerative Proctitis

BACKGROUND

Data on the efficacy of intercellular adhesion molecule-1 antisense oligonucleotide alicaforsen in ulcerative colitis (UC) is inconsistent.

METHODS

All patients, who had received at least one dose of alicaforsen, were analyzed retrospectively. Alicaforsen's efficacy was assessed in patients treated for left-sided UC and proctitis by comparing clinical and (if applicable) endoscopic disease activity before/after treatment.

RESULTS

Twelve patients were treated for left-sided UC or proctitis. Eleven patients received a 6-week course of a once-daily 240 mg alicaforsen enema formulation. In 1 patient, treatment was discontinued, because it was found to be inefficient. Disease activity measured by the partial Mayo score and 6-point symptom score was significantly reduced after treatment (6.0 vs. 2.4, p = 0.011 and 3.7 vs. 1.4, p = 0.008). Faecal calprotectin showed a trend towards reduction (484.4 vs. 179.5 μg/g, p = 0.063). Clinical improvement was achieved in 10 patients (83.3%). In 7 patients, a relapse occurred (70%). Median duration of clinical improvement was 18.0 weeks (range 1-112). Three patients showed an ongoing improvement of >9 months. No adverse events were reported.

CONCLUSIONS

A 6-week course of alicaforsen seemed to be safe and efficacious in inducing clinical improvement in patients with left-sided UC and proctitis. Prolonged clinical improvement was observed in many but not all patients.

Alicaforsen in the treatment of pouchitis

Alicaforsen is a 20-base antisense oligonucleotide inhibiting ICAM-1 production, which is an important adhesion molecule involved in leukocyte migration and trafficking to the site of inflammation. Hitherto, alicaforsen has been granted orphan drug designation and is prescribed as an unlicensed medicine in accordance with international regulation for the treatment of pouchitis and left-sided ulcerative colitis. Given the positive results evolving from one open-label trial and one case series in patients with chronic refractory pouchitis, US FDA has agreed to a rolling submission for a license application for the treatment of pouchitis, which has been recently initiated. Whether alicaforsen leads to higher endoscopic and clinical remission rates as placebo and whether the response can be maintained in the long-term in larger studies is yet unknown. An ongoing multicenter international Phase III trial will definitely address these unanswered questions.

Alicaforsen for the treatment of inflammatory bowel disease

INTRODUCTION

Intracellular adhesion molecule-1 (ICAM-1), is a transmembrane glycoprotein of the immunoglobulin family, constitutively expressed on vascular endothelial cells and upregulated in inflamed colonic tissue. Alicaforsen, a 20 base ICAM-1 anti-sense oligonucleotide and highly selective ICAM-1 inhibitor, down-regulates ICAM-1 mRNA. Areas covered: We review mechanism of action, pharmacokinetics, pre-clinical, clinical and safety data of alicaforsen for the treatment of ulcerative colitis (UC), pouchitis and Crohn's disease (CD). Expert opinion: After 6 weeks of treatment, topical alicaforsen was significantly more effective than placebo in inducing remission in patients with moderate-severe distal UC, with treatment effects lasting up to 30 weeks. No difference was observed in head-head comparison with mesalamine topical enema, although alicaforsen appeared to have more durable treatment effect. Clinical trials of an intravenous formulation in Crohn's disease showed no significant treatment effect compared to placebo. An open-label trial in alicaforsen for pouchitis demonstrated encouraging results, now being assessed in a multi-national phase 3 trial. No major safety signals have been observed in UC patients treated with alicaforsen enemas. The potential as a novel therapy for pouchitis has led to orphan designation for this indication by the FDA and European Medicines Agency.

Clinical Effects of a Topically Applied Toll-like Receptor 9 Agonist in Active Moderate-to-Severe Ulcerative Colitis

BACKGROUND AND AIMS

Toll-like receptors [TLRs] are potential drug targets for immunomodulation. We determined the safety and efficacy of the TLR-9 agonist DNA-based immunomodulatory sequence 0150 [DIMS0150] in ulcerative colitis [UC] patients refractory to standard therapy.

METHODS

In this randomized, double-blind, placebo-controlled trial, 131 patients with moderate-to-severe active UC were randomized to receive two single doses of the oligonucleotide DIMS0150 [30 mg] or placebo administered topically during lower GI endoscopy at baseline and Week 4. The primary endpoint was clinical remission, defined as Clinical Activity Index [CAI] ≤4, at Week 12. Secondary endpoints included mucosal healing and symptomatic remission of key patient-reported outcomes [absence of blood in stool and weekly stool frequency <35].

RESULTS

There was no statistical significant difference between the groups in the induction of clinical remission at Week 12, with 44.4% in the DIMS0150 group vs. 46.5% in the placebo group. However, the proportion of patients who achieved symptomatic remission was 32.1% in the DIMS0150 group vs. 14.0% in the placebo group at Week 4 [p = 0.020], and 44.4% vs. 27.9% at Week 8 [p = 0.061]. More patients on DIMS0150 compared with those on placebo had mucosal healing [34.6% vs. 18.6%; p = 0.09] and histological improvement regarding the Geboes score [30.9% vs. 9.3%; p = 0.0073] at Week 4. Significantly more patients on DIMS0150 were in clinical remission with mucosal healing at Week 4: 21% vs. 4.7% in the placebo group [p = 0.02]. DIMS0150 was well tolerated, and no safety signals compared with placebo were evident.

CONCLUSIONS

Therapy with the topically applied TLR-9 agonist DIMS0150 is a promising and well-tolerated novel therapeutic option for treatment-refractory, chronic active UC patients, warranting further clinical trials.

Oral delivery of macromolecular drugs: Where we are after almost 100years of attempts

Since the first attempt to administer insulin orally in humans more than 90years ago, the oral delivery of macromolecular drugs (>1000g/mol) has been rather disappointing. Although several clinical pilot studies have demonstrated that the oral absorption of macromolecules is possible, the bioavailability remains generally low and variable. This article reviews the formulations and biopharmaceutical aspects of orally administered biomacromolecules on the market and in clinical development for local and systemic delivery. The most successful approaches for systemic delivery often involve a combination of enteric coating, protease inhibitors and permeation enhancers in relatively high amounts. However, some of these excipients have induced local or systemic adverse reactions in preclinical and clinical studies, and long-term studies are often missing. Therefore, strategies aimed at increasing the oral absorption of macromolecular drugs should carefully take into account the benefit-risk ratio. In the absence of specific uptake pathways, small and potent peptides that are resistant to degradation and that present a large therapeutic window certainly represent the best candidates for systemic absorption. While we acknowledge the need for systemically delivering biomacromolecules, it is our opinion that the oral delivery to local gastrointestinal targets is currently more promising because of their accessibility and the lacking requirement for intestinal permeability enhancement.

Antisense approach to inflammatory bowel disease: prospects and challenges

Despite the great success of anti-tumour necrosis factor-based therapies, the treatment of Crohn's disease (CD) and ulcerative colitis (UC) still remains a challenge for clinicians, as these drugs are not effective in all patients, their efficacy may wane with time, and their use can increase the risk of adverse events and be associated with the development of new immune-mediated diseases. Therefore, new therapeutic targets are currently being investigated both in pre-clinical studies and in clinical trials. Among the technologies used to build new therapeutic compounds, the antisense oligonucleotide (ASO) approach is slowly gaining space in the field of inflammatory bowel diseases (IBDs), and three ASOs have been investigated in clinical trials. Systemic administration of alicaforsen targeting intercellular adhesion molecule-1, a protein involved in the recruitment of leukocytes to inflamed intestine, was not effective in CD, even though the same compound was of benefit when given as an enema to UC patients. DIMS0150, targeting nuclear factor (NF) κB-p65, a transcription factor that promotes pro-inflammatory responses, was very promising in pre-clinical studies and is currently being tested in clinical trials. Oral mongersen, targeting Smad7, an intracellular protein that inhibits transforming growth factor (TGF)-β1 activity, was safe and well tolerated by CD patients, and the results of a phase II clinical trial showed the efficacy of the drug in inducing clinical remission in patients with active disease. In this leading article, we review the rationale and the clinical data available regarding these three agents, and we discuss the challenge of using ASOs in IBD.

Nanomedicine and drug delivery strategies for treatment of inflammatory bowel disease

Crohn’s disease and ulcerative colitis are two important categories of human inflammatory bowel disease (IBD). Because the precise mechanisms of the inflammation and immune responses in IBD have not been fully elucidated, the treatment of IBD primarily aims to inhibit the pathogenic factors of the inflammatory cascade. Inconsistencies exist regarding the response and side effects of the drugs that are currently used to treat IBD. Recent studies have suggested that the use of nanomedicine might be advantageous for the treatment of intestinal inflammation because nano-sized molecules can effectively penetrate epithelial and inflammatory cells. We reviewed nanomedicine treatments, such as the use of small interfering RNAs, antisense oligonucleotides, and anti-inflammatory molecules with delivery systems in experimental colitis models and clinical trials for IBD based on a systematic search. The efficacy and usefulness of the treatments reviewed in this manuscript have been demonstrated in experimental colitis models and clinical trials using various types of nanomedicine. Nanomedicine is expected to become a new therapeutic approach to the treatment of IBD.

EPA- and DHA-derived resolvins' actions in inflammatory bowel disease

Inflammatory bowel diseases are chronic diseases divided into two major forms, ulcerative colitis and Crohn's disease, which are both associated with a chronic inflammatory condition of the gastrointestinal tract. Recent studies have shown that the resolution of inflammatory conditions is a biosynthetically active process where new pro-resolution lipid mediators derived from omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), such as E- and D-series resolvins, protectins, and macrophage mediator in resolving inflammation (maresins), have potent anti-inflammatory activity and serve as specialised mediators that play an important role in the resolution of inflammation. Recent studies have also shown the role of resolvins in referred hyperalgesia associated with different inflammatory processes, such as the visceral pain caused by inflammatory bowel disease. There are many reports describing the principal effects of EPA- and DHA-derived mediators in experimental models of inflammatory bowel diseases. This review focuses on the recent studies on the important role played by pro-resolution lipid mediators in controlling the inflammatory process associated with inflammatory bowel diseases.

Inflammatory Bowel Disease: An Overview of Immune Mechanisms and Biological Treatments

Inflammatory bowel diseases (IBD) are characterized by chronic inflammation of the intestinal tract associated with an imbalance of the intestinal microbiota. Crohn's disease (CD) and ulcerative colitis (UC) are the most widely known types of IBD and have been the focus of attention due to their increasing incidence. Recent studies have pointed out genes associated with IBD susceptibility that, together with environment factors, may contribute to the outcome of the disease. In ulcerative colitis, there are several therapies available, depending on the stage of the disease. Aminosalicylates, corticosteroids, and cyclosporine are used to treat mild, moderate, and severe disease, respectively. In Crohn's disease, drug choices are dependent on both location and behavior of the disease. Nowadays, advances in treatments for IBD have included biological therapies, based mainly on monoclonal antibodies or fusion proteins, such as anti-TNF drugs. Notwithstanding the high cost involved, these biological therapies show a high index of remission, enabling a significant reduction in cases of surgery and hospitalization. Furthermore, migration inhibitors and new cytokine blockers are also a promising alternative for treating patients with IBD. In this review, an analysis of literature data on biological treatments for IBD is approached, with the main focus on therapies based on emerging recombinant biomolecules.

Biological therapy for ulcerative colitis

Ulcerative colitis (UC) is a major form of inflammatory bowel disease (IBD) worldwide. Better understanding of the pathogenesis of UC has led to the development of novel therapeutic agents that target specific mediators of the inflammatory cascade. A number of biological agents have been approved by the U.S. Food and Drug Administration (FDA) for the treatment of UC and several more are currently in various phases of drug development. The commonly used agents include TNFα antagonists (e.g. infliximab, adalimumab, and golimumab) and anti-integrin agents (vedolizumab). These biological agents have profoundly influenced the management of UC patients, especially those with refractory disease. This paper reviews the currently available knowledge and evidence for the use of various biological agents in the treatment of UC.

IL-17A alone weakly affects the transcriptome of intestinal epithelial cells but strongly modulates the TNF-α-induced expression of inflammatory mediators and inflammatory bowel disease susceptibility genes

BACKGROUND

In contrast to anti-TNF-α antibodies, anti-IL-17A antibodies lacked clinical efficacy in a trial with patients suffering from Crohn's disease. We therefore analyzed how IL-17A modulates the inflammatory response elicited by TNF-α in intestinal epithelial cells (IEC).

METHODS

Target mRNA levels in IEC and colonic biopsies were assessed by RNA microarray and quantitative real-time PCR. Signaling pathways were analyzed using receptor neutralization and pharmacological inhibitors. Target protein levels were determined by immunoblotting.

RESULTS

Microarray analysis demonstrated that IL-17A alone is a weak inducer of gene expression in IEC (29 regulated transcripts), but significantly affected the TNF-α-induced expression of 547 genes, with strong amplification of proinflammatory chemokines and cytokines (>200-fold increase of CCL20, CXCL1, and CXCL8). Interestingly, IL-17A differentially modulated the TNF-α-induced expression of several inflammatory bowel disease susceptibility genes in IEC (increase of JAK2 mRNA, decrease of FUT2, ICAM1, and LTB mRNA). Negative regulation of ICAM-1 by IL-17A was verified on protein level. The significance of these findings is emphasized by inflamed lesions of patients with inflammatory bowel disease demonstrating significant correlations (P < 0.01, Rho, 0.57-0.85) for JAK2, ICAM1, and LTB mRNA with IL17A and TNF mRNA.

CONCLUSIONS

Our study demonstrates the modulation of inflammatory bowel disease susceptibility gene mRNA in IEC as a novel important property of IL-17A. Given the weak impact of sole IL-17A stimulation on IEC target gene expression, our study provides an important explanation for the lack of clinical efficacy of sole IL-17A neutralization, but suggests a beneficial effect of combined IL-17A/TNF-α that is currently in clinical development.

Managing intractable proctitis and the problematic pouch

Proctitis accounts for a significant proportion of cases of ulcerative colitis (UC), and some patients subsequently develop more extensive disease. However, most patients continue to have limited inflammation, although the changes in the distal colon and rectum can occasionally be severe, and symptoms of increased frequency, rectal bleeding and urgency can be as disabling as they are for patients with more extensive colitis. Furthermore, although symptoms are typically well controlled with standard medications, medically refractory proctitis poses particular problems. Patients generally are not systemically unwell, and there is no added fear of cancer. Therefore, the prospect of colectomy for such limited disease is resisted by patients, physicians and surgeons alike. Unusual therapies, often delivered locally by enema or suppository, have been tested in small case series without definitive outcomes. The pathogenesis of such limited, yet intractable inflammation remains unclear, and the differential diagnosis should be carefully reviewed to ensure that local disease, whether it is infectious, vascular, or a result of injury or degeneration, is not overlooked. Ileo-anal pouch formation is the surgery of choice for about 20% of patients with UC who undergo colectomy. In the majority of cases, this surgery results in an acceptable quality of life and freedom from a stoma. However, in a sizeable minority of cases, pouch dysfunction can cause intractable problems. The causes of pouch dysfunction are varied and must all be considered carefully, particularly in refractory cases. Pouchitis is a common issue and is usually transient and easily treated. However, refractory and chronic pouchitis can be challenging. Ischaemia, injury, infection and Crohn's disease can all cause refractory pouch dysfunction. In a minority of cases, there appears to be no apparent organic pathology, and the presumptive diagnosis is that of a functional pouch disorder. Although it is much rarer, neoplastic changes in the pouch must also be considered, and the risk managed appropriately. The management of both intractable proctitis and the problematic pouch is made more challenging by the wide differential diagnosis that must be considered and by the paucity of high-quality clinical trials to support any one therapy. Key strategies to overcoming these limitations include methodical and systematic investigation and review, and a willingness to tailor therapy to the individual patient. Clinical trials of new treatments should be supported, and data from the experience with small cohorts of patients should be meticulously collected, critically analysed and widely disseminated.

Vedolizumab for the treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease of the large intestine that often develops in the young. A few new treatment options have become available in the past decade, but management of a large proportion of patients still remains challenging because of side effects, unresponsiveness and cost. A novel strategy targeting trafficking of immune cells to the sites of inflammation involves reducing expression or binding of adhesion molecules to integrins. Natalizumab was the first therapeutic antibody blocking infiltration of leukocytes, but because of lack of selectivity to the gut and associated risk of progressive multifocal leukoencephalopathy, it will probably never be tested in ulcerative colitis. In this article we discuss molecules that block leukocyte trafficking to inflamed bowel that have been tested in ulcerative colitis. Because of favourable efficacy and safety data, we will review the development, pharmacology and clinical data of vedolizumab, a gut-selective α4β7 antibody, in depth.

Efficacy of topical versus oral 5-aminosalicylate for treatment of 2,4,6-trinitrobenzene sulfonic acid-induced ulcerative colitis in rats

5-aminosalicylic acid (5-ASA) is drug of choice for the treatment of ulcerative colitis (UC). In this study, the efficacy of topical versus oral 5-ASA for the treatment of UC was examined as well as the action mechanism of this medication. A flexible tube was inserted into the rat cecum to establish a topical administration model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced UC. A total of 60 rats were divided into sham operation group (receiving an enema of 0.9% saline solution instead of the TNBS solution via the tube), model group, topical 5-ASA group, oral Etiasa group (a release agent of mesalazine used as positive control) and oral 5-ASA group (n=12 each). Different treatments were administered 1 day after UC induction. The normal saline (2 mL) was instilled twice a day through the tube in the sham operation group and model group. 5-ASA was given via the tube in the topical 5-ASA group (7.5 g/L, twice per day, 100 mg/kg), and rats in the oral Etiasa group and oral 5-ASA group intragastrically received Etiasa (7.5 g/L, twice per day, 100 mg/kg) and 5-ASA (7.5 g/L, twice per day, 100 mg/kg), respectively. The body weight was recorded every day. After 7 days of treatment, blood samples were drawn from the heart to harvest the sera. Colonic tissues were separated and prepared for pathological and related molecular biological examinations. The concentrations of 5-ASA were detected at different time points in the colonic tissues, feces and sera in different groups by using the high pressure liquid chromatography (HPLC). The results showed that the symptoms of acute UC, including bloody diarrhea and weight loss, were significantly improved in topical 5-ASA-treated rats. The colonic mucosal damage, both macroscopical and histological, was significantly relieved and the myeloperoxidase activity was markedly decreased in rats topically treated with 5-ASA compared with those treated with oral 5-ASA or Etiasa. The mRNA and protein expression of IL-1β, IL-6, and TNF-α was down-regulated in the colonic tissue of rats topically treated with 5-ASA, significantly lower than those from rats treated with oral 5-ASA or Etiasa. The concentrations of 5-ASA in the colonic tissue were significantly higher in the topical 5-ASA group than in the oral 5-ASA and oral Etiasa groups. It was concluded that the topical administration of 5-ASA can effectively increase the concentration of 5-ASA in the colonic tissue, decrease the expression of proinflammatory cytokines, alleviate the colonic pathological damage and improve the symptoms of TNBS-induced acute UC in rats.

Microbial ecological agents and inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a chronic non-specific inflammatory condition of the gastrointestinal tract with unknown etiology. During the exploration of the etiology, treatment and other aspects of IBD, it has been gradually realized that microbial ecological agents (MEAs) are helpful in the treatment of IBD. This article reviews the relationship between MEAs and IBD with regard to the intestinal environment in IBD, the therapeutic effect of MEA in IBD and the possible mechanisms involved.