Effect of aminophenols (5-ASA and 4-ASA) on colonic interleukin-1 generation

An In Vitro Study Evaluating the Safety of Mesalazine on Human Nasoepithelial Cells

Chronic rhinosinusitis (CRS) is a disease characterised by the inflammation of the nasal and paranasal cavities. It is a widespread condition with considerable morbidity for patients. Current treatment for chronic rhinosinusitis consists of appropriate medical therapy followed by surgery in medically resistant patients. Although oral steroids are effective, they are associated with significant morbidity, and disease recurrence is common when discontinued. The development of additional steroid sparing therapies is therefore needed. Mesalazine is a commonly used therapeutic in inflammatory bowel disease, which shares a similar disease profile with chronic rhinosinusitis. This exploratory in vitro study aims to investigate whether mesalazine could be repurposed to a nasal wash, which is safe on human nasoepithelial cells, and retains its anti-inflammatory effects. CRS patients' human nasal epithelial cells (HNECs) were collected. HNECs were grown at an air-liquid interface (ALIs) and in a monolayer and challenged with mesalazine or a non-medicated control. Transepithelial electrical resistance, paracellular permeability, and toxicity were measured to assess epithelial integrity and safety. The anti-inflammatory effects of mesalazine on the release of interleukin (IL)-6 and tumour necrosis factor alpha (TNF-α) were analysed using human leukemia monocytic cell line (THP-1). mesalazine did not impact the barrier function of HNEC-ALIs and was not toxic when applied to HNECs or THP-1 cells at concentrations up to 20 mM. mesalazine at 0.5 and 1 mM concentrations significantly inhibited TNF-α release by THP-1 cells. mesalazine effectively decreases TNF-α secretion from THP-1 cells, indicating the possibility of its anti-inflammatory properties. The safety profile of mesalazine at doses up to 20 mM suggests that it is safe when applied topically on HNECs.

Delivery Strategies of Probiotics from Nano- and Microparticles: Trends in the Treatment of Inflammatory Bowel Disease-An Overview

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder, most known as ulcerative colitis (UC) and Crohn's disease (CD), that affects the gastrointestinal tract (GIT), causing considerable symptoms to millions of people around the world. Conventional therapeutic strategies have limitations and side effects, prompting the exploration of innovative approaches. Probiotics, known for their potential to restore gut homeostasis, have emerged as promising candidates for IBD management. Probiotics have been shown to minimize disease symptoms, particularly in patients affected by UC, opening important opportunities to better treat this disease. However, they exhibit limitations in terms of stability and targeted delivery. As several studies demonstrate, the encapsulation of the probiotics, as well as the synthetic drug, into micro- and nanoparticles of organic materials offers great potential to solve this problem. They resist the harsh conditions of the upper GIT portions and, thus, protect the probiotic and drug inside, allowing for the delivery of adequate amounts directly into the colon. An overview of UC and CD, the benefits of the use of probiotics, and the potential of micro- and nanoencapsulation technologies to improve IBD treatment are presented. This review sheds light on the remarkable potential of nano- and microparticles loaded with probiotics as a novel and efficient strategy for managing IBD. Nonetheless, further investigations and clinical trials are warranted to validate their long-term safety and efficacy, paving the way for a new era in IBD therapeutics.

Gut Microbiome-Wide Search for Bacterial Azoreductases Reveals Potentially Uncharacterized Azoreductases Encoded in the Human Gut Microbiome

The human gut is home to trillions of microorganisms that are responsible for the modification of many orally administered drugs, leading to a wide range of therapeutic outcomes. Prodrugs bearing an azo bond are designed to treat inflammatory bowel disease and colorectal cancer via microbial azo reduction, allowing for topical application of therapeutic moieties to the diseased tissue in the intestines. Despite the inextricable link between microbial azo reduction and the efficacy of azo prodrugs, the prevalence, abundance, and distribution of azoreductases have not been systematically examined across the gut microbiome. Here, we curated and clustered amino acid sequences of experimentally confirmed bacterial azoreductases and conducted a hidden Markov model-driven homolog search for these enzymes across 4644 genome sequences present in the representative Unified Human Gastrointestinal Genomes collection. We identified 1958 putative azo-reducing species, corroborating previous findings that azo reduction appears to be a ubiquitous function of the gut microbiome. However, through a systematic comparison of predicted and confirmed azo-reducing strains, we hypothesize the presence of uncharacterized azoreductases in 25 prominent strains of the human gut microbiome. Finally, we confirmed the azo reduction of Acid Orange 7 by multiple strains of Fusobacterium nucleatum, Bacteroides fragilis, and Clostridium clostridioforme Together, these results suggest the presence and activity of many uncharacterized azoreductases in the human gut microbiome and motivate future studies aimed at characterizing azoreductase genes in prominent members of the human gut microbiome. SIGNIFICANCE STATEMENT: This work systematically examined the prevalence, abundance, and distribution of azoreductases across the healthy and inflammatory bowel disease human gut microbiome, revealing potentially uncharacterized azoreductase genes. It also confirmed the reduction of Acid Orange 7 by strains of Fusobacterium nucleatum, Bacteroides fragilis, and Clostridium clostridioforme.

Pre-clinical Investigation of Protective Effect of Nutraceutical D-Glucosamine on TNBS-induced Colitis

The level of precursors involved in the biosynthesis of glycosaminoglycan (GAG), glucosamine synthase, and N-acetyl glucosamine (NAG), are significantly reduced in inflammatory bowel disease (IBD). This results in deficient GAG content in mucosa, which eventually disrupts the gut wall integrity, provoking abnormal immunological responses. This is characterized by colossal liberation of inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interleukins (IL), and reactive oxygen species provoking colonic inflammation. D-glucosamine (D-GLU) is reported to suppress oxidative stress, and pro-inflammatory cytokines and acts as a starting material for biosynthesis of NAG. The potential of D-GLU and its combination with mesalamine (5-ASA) was investigated in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-instigated IBD in Wistar rats. Standard and test drugs were given orally for five days to separate groups of rats. Colonic inflammation was evaluated by disease activity score rate (DASR), colon/body weight ratio, colon length, diameter, colon pH, histological injury and score. Inflammatory biomarkers IL-1β, TNF-α, along with reduced glutathione (GSH), and malondialdehyde (MDA) were assessed. Combination of D-GLU +5-ASA significantly ameliorated severity of colonic inflammation by lowering DASR (P < 0.001) and colon/body weight ratio (P < 0.001), restored the colonic architecture and suppressed the histopathological score (P < 0.001), along with the absence of major adverse reactions. The combination suppressed the levels of inflammatory markers (P < 0.001) and MDA (P < 0.001) while enhancing GSH level (P < 0.001). In comparison to individual 5-ASA and D-GLU, combination of drugs significantly diminished colitis severity through their combined anti-inflammatory and antioxidant effects by acting on multiple targets simultaneously. The combination holds remarkable potential in the management of IBD.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Inflammatory Bowel Disease

According to recent clinical consensus, pharmacotherapy of inflammatory bowel disease (IBD) is, or should be, personalized medicine. IBD treatment is complex, with highly different treatment classes and relatively few data on treatment strategy. Although thorough evidence-based international IBD guidelines currently exist, appropriate drug and dose choice remains challenging as many disease (disease type, location of disease, disease activity and course, extraintestinal manifestations, complications) and patient characteristics [(pharmaco-)genetic predisposition, response to previous medications, side-effect profile, necessary onset of response, convenience, concurrent therapy, adherence to (maintenance) therapy] are involved. Detailed pharmacological knowledge of the IBD drug arsenal is essential for choosing the right drug, in the right dose, in the right administration form, at the right time, for each individual patient. In this in-depth review, clinical pharmacodynamic and pharmacokinetic considerations are provided for tailoring treatment with the most common IBD drugs. Development (with consequent prospective validation) of easy-to-use treatment algorithms based on these considerations and new pharmacological data may facilitate optimal and effective IBD treatment, preferably corroborated by effectiveness and safety registries.

Pharmacotherapy of ulcerative colitis - current status and emerging trends

Ulcerative colitis (UC) is a chronic mucosal inflammation of the large intestine restricted to the rectum and colon. Its clinical course follows an intermittent pattern with episodes of relapse, followed by remission and eventually resulting in mucosal damage. Although there is no permanent cure for UC, the currently available pharmacotherapy aims to induce and maintain clinical remission, promote the healing of colonic mucosa and avert any surgical intervention. The conventional drug therapy comprising of 5-aminosalicylates, thiopurines and corticosteroids has advanced recently in terms of formulations and dosing schedule, resulting in improved efficacy, safety and compliance. Calcineurin inhibitors, such as cyclosporin and tacrolimus, have emerged as steroid sparing agents. The treatment paradigm of UC patients who are refractory to conventional drugs has changed in view of the availability of biologics. Currently, there are four biologics approved by the US FDA for the treatment of UC, namely, infliximab, adalimumab, golimumab and vedolizumab, and several others are undergoing clinical trial. In this comprehensive review, the advantages and limitations of the medical therapy of UC are elaborated with an emphasis on the pharmacokinetic and pharmacodynamic aspects of the drugs.

Xylan from Pineapple Stem Waste: a Potential Biopolymer for Colonic Targeting of Anti-inflammatory Agent Mesalamine

We have successfully conjugated mesalamine (5-aminosalicylic acid, 5-ASA) with xylan, a biopolymer isolated from pineapple stem waste, to form xylan-5-ASA conjugate. The biopolymer was used to provide colon-targeting properties for 5-ASA, a golden standard anti-inflammatory agent commonly used for ulcerative colitis treatment. A series of data from FTIR spectroscopy, UV-Vis spectrophotometry, and HPLC confirmed the xylan-5-ASA conjugate formation. To ensure successful colon targeting properties, in vitro and in vivo drug release studies after oral administration of xylan-5-ASA conjugate to Wistar rats were performed. Xylan-5-ASA conjugate was able to retain 5-ASA release in the upper gastrointestinal tract fluid simulation but rapidly released 5-ASA in the rat colon fluid simulation. In vivo release profile shows a very low peak plasma concentration, reached at 6 h after xylan-5-ASA conjugate administration. The delayed release and the lower bioavailability of 5-ASA from xylan-5-ASA conjugate administration compared to free 5-ASA administration confirmed the successful local colon delivery of 5-ASA using xylan-5-ASA conjugate. The administration of xylan-5-ASA conjugate also exhibited greater efficacy in recovering 2,4,6-trinitrobenzene sulfonic acid-induced colon ulcer compared to free 5-ASA administration. Taken together, xylan isolated from pineapple stem waste is promising to obtain colon targeting property for 5-ASA.

5-Aminosalicylic acid downregulates the growth and virulence of Escherichia coli associated with IBD and colorectal cancer, and upregulates host anti-inflammatory activity

5-aminosalicylate (5-ASA) is widely prescribed for the treatment of inflammatory bowel disease (IBD) and prevention of inflammation-associated colorectal cancer (CRC). Its clinical effect is widely attributed to modulation of host inflammatory responses. However, the recent association of intestinal dysbiosis and selective enrichment in Escherichia coli in patients with IBD and CRC raises the possibility that 5-ASA might also affect the enteric microflora. The aim of this study was to investigate the effect of 5-ASA on the growth and virulence of E. coli associated with IBD and CRC, and its impact on host cell inflammatory responses. Our results show that 5-ASA inhibited E. coli growth in a dose-dependent manner and downregulated the expression of bacterial virulence genes associated with IBD (fliC, fimH, ompC, yfgL, nlpL, lpfA, htrA, dsbA, fyuA, and chuA) and CRC (pks). 5-ASA inhibited E. coli motility (30-70%), epithelial adherence and invasion, and IL-8 secretion (p < 0.05). 5-ASA reduced E. coli survival in J774A.1 macrophages by 20 to 50% (p < 0.01) and TNF-α secretion by infected macrophages up to 30% (p < 0.05). In addition, 5-ASA reduced DNA damage in epithelial cells (Caco-2) induced by pks-positive E. coli. Our results reveal a multifaceted and previously unrecognized effect of 5-ASA on the growth and virulence of IBD- and CRC-associated E. coli, in addition to its inhibitory effect on host cell inflammatory responses. These results suggest that 5-ASA may abrogate the proinflammatory and oncogenic effects of E. coli in patients with IBD and CRC.

Regulatory framework on bioequivalence criteria for locally acting gastrointestinal drugs: the case for oral modified release mesalamine formulations

INTRODUCTION

Bioequivalence testing for locally acting gastrointestinal drugs is a challenging issue for both regulatory authorities and pharmaceutical industries. The international regulatory framework has been characterized by the lack of specific bioequivalence tests that has generated a negative impact on the market competition and drug use in clinical practice. Areas covered: This review article provides an overview of the European Union and United States regulatory frameworks on bioequivalence criteria for locally acting gastrointestinal drugs, also discussing the most prominent scientific issues and advances that has been made in this field. A focus on oral modified release mesalamine formulations will be also provided, with practical examples of the regulatory pathways followed by pharmaceutical companies to determine bioequivalence. Expert commentary: The development of a scientific rationale to demonstrate bioequivalence in this field has been complex and often associated with uncertainties related to scientific and regulatory aspects. Only in recent years, thanks to advanced knowledge in this field, the criteria for bioequivalence assessment are undergoing substantial changes. This new scenario will likely result in a significant impact on pharmaceutical companies, promoting more competition through a clearer regulatory approach, conceived for streamlining the demonstration of therapeutic equivalence for locally acting gastrointestinal drugs.

Pre- and posttherapy assessment of intestinal soluble mediators in IBD: where we stand and future perspectives

Inflammatory bowel disease (IBD) is a chronic inflammatory condition characterized by an abnormal immune response against food or bacterial antigens in genetically predisposed individuals. Several factors of innate and adaptive immune system take part in the inflammatory process, probably actively contributing in endoscopic and histological healing at molecular level. Although it is difficult to discriminate whether they are primary factors in determining these events or they are secondarily involved, it would be interesting to have a clear map of those factors in order to have a restricted number of potentially "good candidates" for mucosal healing. The present review will present a class of these factors and their modulation in course of therapy, starting from pathogenic studies involving several treatments associated with good clinical outcomes. This approach is meant to help in the difficult task of identifying "good candidates" for healing signatures, which could also be possible new therapeutic targets for clinical management of IBD patients.

Topical therapy

Topical therapy with mesalazine and/or corticosteroids is the standard treatment for patients with distal ulcerative colitis. Rectal mesalazine is more effective than rectal systemically active corticosteroids or topically active corticosteroids like budesonide. In patients with mild to moderately active distal ulcerative colitis, topical mesalazine is therefore the treatment of choice. Doses of 1 g or higher are equally effective. The period of treatment is important (4 weeks are more effective than 2 weeks). In the case of nonresponse or nontolerability of rectal mesalazine, rectal budesonide is indicated. The standard dose of budesonide is 2 mg/day. This does not usually induce any corticosteroid-associated adverse events. Treatment with rectal mesalazine plus rectal topically active corticosteroids is even more effective than treatment with either substance alone. To overcome adherence problems with rectal therapy, rectal foam preparations have been developed which are usually better tolerated than enemas.

Design, Synthesis, and Testing of a Molecular Truck for Colonic Delivery of 5-Aminosalicylic Acid

A molecular scaffold bearing eight terminal alkyne groups was synthesized from sucrose. Eight copies of an azide-terminated, azo-linked precursor to 5-aminosalicylic acid were attached to the scaffold via copper(I)-catalyzed azide-alkyne cycloaddition. The resulting compound was evaluated in a DSS model of colitis in BALB/c mice against sulfasalazine as a control. Two independent studies verified that the novel pro-drug, administered in a dose calculated to result in an equimolar 5-ASA yield, outperformed sulfasalazine in terms of protection from mucosal inflammation and T cell activation. A separate study established that 5-ASA appeared in feces produced 24-48 hours following administration of the pro-drug. Thus, a new, orally administered pro-drug form of 5-aminosalicylic acid has been developed and successfully demonstrated.

Multi-Matrix System (MMX®) mesalamine for the treatment of mild-to-moderate ulcerative colitis

INTRODUCTION

Ulcerative colitis (UC) is an inflammatory disease of the colon characterized by periods of active disease and remission. The pathogenesis of this disease is likely a complex interaction of genetic predisposition, environmental factors, and immune system dysregulation, and is not completely understood. A Multi-MatriX (MMX®) system formulation of mesalamine, MMX mesalamine (SPD476; Lialda®; Mesavancol®; Mezavant®), allows for high-dose, once-daily dosing for patients with mild-to-moderate UC. Mesalamine is a topically active agent with anti-inflammatory properties.

AREAS COVERED

Available literature regarding MMX mesalamine is extensively reviewed in this article, covering its chemical makeup, mechanism of action, pharmaceutics and pharmacokinetics, clinical efficacy, and safety and tolerability.

EXPERT OPINION

A dose of 2.4 and 4.8 g was used in large Phase III clinical trials and was efficacious for induction of clinical and endoscopic remission in UC. MMX mesalamine was also efficacious in large multicenter maintenance studies for the maintenance of clinical and endoscopic remission. The introduction of the first once-daily mesalamine has given practitioners and patients more flexibility in dosing administration, which will ultimately lead to higher satisfaction and improved clinical outcomes.

Identification of pancreatic glycoprotein 2 as an endogenous immunomodulator of innate and adaptive immune responses

Pancreatic autoantibodies are Crohn disease-specific serologic markers. The function and immunological role of their recently identified autoantigen, glycoprotein 2 (GP2), are unknown. We therefore investigated the impact of GP2 on modulation of innate and adaptive immune responses to evaluate its potential therapeutic use in mucosal inflammation. Our data indicate a previously unknown function for GP2 as an immunomodulator. GP2 was ubiquitously expressed on cells vital to mucosal immune responses. The expression of GP2 was upregulated on activated human T cells, and it was further influenced by pharmaceutical TNF-α inhibitors. Recombinant GP2 significantly decreased human intestinal epithelial cells, mucosal and peripheral T cell proliferation, apoptosis, and activation, and it distinctly modulated cytokine secretion. Furthermore, intestinal epithelial cells stimulated with GP2 potently attracted T cells. In conclusion, we demonstrate a novel role for GP2 in immune regulation that could provide a platform for new therapeutic interventions in the treatment of Crohn disease.

Aminosalicylates

Symptomatic diverticular disease has a high prevalence in countries with a western lifestyle. Besides antibiotics for acute diverticulitis there are no established medical interventions to prevent or to treat symptomatic diverticular disease. Due to its broad spectrum of anti-inflammatory activities, mesalazine is a candidate for the treatment of symptomatic diverticular disease. A review of the literature shows that randomized open studies using various treatment designs suggest a protective role of mesalazine in preventing recurrences of diverticulitis. Currently, 5 randomized placebo-controlled trials are active which will clarify the role of mesalazine to prevent recurrence of diverticulitis in the near future. Several randomized uncontrolled studies suggest that mesalazine improves symptoms in patients with symptomatic uncomplicated diverticular disease. The analysis of secondary end points from two randomized placebo-controlled trials suggests that mesalazine improves symptoms in diverticular disease although both studies failed to show a statistically significant advantage for mesalazine for the primary study end point. In segmental colitis associated with diverticulosis no prospective systematic studies are available. However, several case reports show a high efficacy of mesalazine in segmental colitis associated with diverticulosis.

Expanding applications: the potential usage of 5-aminosalicylic acid in diverticular disease

Diverticular disease is a common bowel condition, the pathogenesis of which is incompletely understood. Acute exacerbations of diverticular disease usually require dietary changes, antibiotic therapy, and may necessitate urgent surgery. Approximately 25-33% of patients experience symptomatic and acute inflammatory disease recurrence, suggesting that current long-term management is inadequate. Because inflammatory complications of diverticular disease, including diverticulitis, are similarities to inflammatory bowel diseases, evidence suggests that patients may respond to anti-inflammatory therapies used in these conditions. Here, we explore the rationale and evidence for use of inflammatory bowel disease treatment, namely 5-aminosalicylic acid (5-ASA; mesalamine), in diverticular disease, and review clinical data on the efficacy of mesalamine either alone or in combination with other agents for the treatment of diverticular disease. PubMed and conference abstracts were searched for clinical studies examining the use of mesalamine in treating diverticular disease. Studies were evaluated for treatment efficacy in symptom reduction, recurrence prevention, or improving quality of life. The results of our search suggest that single-agent mesalamine can reduce diverticular disease symptoms and improve quality of life more effectively than antibiotic treatment alone. Mesalamine in combination with antibiotics can also reduce symptoms and improve quality of life with greater efficacy than either treatment alone. Combining mesalamine and probiotics treatments may reduce recurrent attacks of diverticular disease. Further randomized, well-controlled studies are required for validation; however, it seems that mesalamine is an important agent in future diverticular disease management.

Aminosalicylates

Aminosalicylates are the most common drugs for the primary treatment of inflammatory bowel disease. Various pro-drugs and formulations were developed in order to improve pharmacological profiles, optimize bioavailability and to gain highest efficacy in the treatment of ulcerative colitis (UC) and Crohn's disease. In vitro studies have greatly contributed to the understanding of the molecular actions in vivo and clinical studies have proven aminosalicylates to be effective and safe. This review summarizes the current knowledge on the molecular, pharmacological and clinical properties of aminosalicylates with respect to chemoprevention for UC-associated colorectal cancer.

Review article: delivery and efficacy of topical 5-aminosalicylic acid (mesalazine) therapy in the treatment of ulcerative colitis

BACKGROUND

The use of topical therapy in the treatment of ulcerative colitis has declined in recent years despite evidence of good efficacy.

AIMS

To review US prescription trends for 5-aminosalicylic acid (5-ASA) since the US approval of Asacol extended-release oral mesalazine (mesalamine) in 1992; to estimate the optimal level of 5-ASA exposure in the distal colon; to determine factors influencing distal colonic exposures; and to compare the effectiveness of different 5-ASA formulations (oral, topical suspension, foam, suppositories) in clinical trials.

METHODS

Review of clinical trials, physiologic studies and prescription trends of various mesalazine formulations for treatment of distal ulcerative colitis.

RESULTS

Between 1992 and 2009, prescriptions for oral mesalazine increased sixfold, whereas topical suspensions declined by 10%. In clinical trials, topical therapy resulted in higher remission and clinical response rates than oral therapy, with trends to earlier improvement. The mucosal concentrations of 5-ASA achieved by topical agents in the distal colon were up to 200-fold higher than those achieved by oral administration alone. Despite active colitis, over 40% of a topically administered 4 g 5-ASA suspension (equal to 1.6 g) reached the sigmoid colon. This likely represents a therapeutic exposure of 5-ASA. Although topical therapies are less convenient than oral medications, treatment algorithms have failed to take into account quality of life improvements resulting from more rapid and complete treatment response.

CONCLUSIONS

Topical mesalazine therapy is superior to oral therapy in distal ulcerative colitis for both therapeutic response and drug delivery. Practice patterns should be re-evaluated in light of this information.

Clinical pharmacology of 5-ASA compounds in inflammatory bowel disease

Mesalamine has been the first-line of therapy in patients with inflammatory bowel disease (IBD) since the 1960s. This article serves as a review of the different 5-aminosalicylic acid compounds, release formulations, use and dosing in the treatment of IBD, in particular ulcerative colitis.

Mesalazine in inflammatory bowel disease: a trendy topic once again?

5-aminosalicylic acid (5-ASA) preparations (eg, mesalazine, mesalamine) are well-established preparations used in the management of inflammatory bowel disease. These drugs are most useful for the treatment of mild to moderate flares of ulcerative colitis and, especially, for maintenance of remission. Although most gastroenterologists are very familiar with these drugs, the interest in these drugs has undergone a resurgence, with new preparations offering convenience and high dosage, while preserving their customary safety. New dosage regimens are likely to become standard practice in the near future. There is also considerable interest in chemoprevention of colorectal cancer in the context of inflammatory bowel disease, and the role of long-term maintenance therapy with 5-ASAs in achieving such chemoprevention. A mechanism of action for such chemoprevention has been provided by the agonism of the peroxisome proliferator-activated receptor-gamma by 5-ASA, which unifies its efficacy as an anti-inflammatory and chemopreventive agent. In the future, even more effective agents based on 5-ASA are expected, based on more powerful agonism of peroxisome proliferator-activated receptor-gamma; 5-ASA preparations have become 'trendy' again.

Update on the role of modified release mesalamine in the management of ulcerative colitis and Crohn's disease

5-aminosalicyclates (5-ASA) remain a key first-line therapy for patients with ulcerative colitis (UC). A range of 5-ASA preparations is available and Eudragit-S^® coated modified release formulations of mesalamine, such as Asacol^®, remain among the most popular choices. We here review the current understanding of the mechanism of action of 5-ASA in inflammatory bowel disease. We evaluate evidence supporting the efficacy and safety of modified release mesalamine for both induction and remission maintenance in UC, including a review of the data from the recent ASCEND studies. We also examine the controversial issue of the role of mesalamine in treatment of Crohn’s disease (CD) and highlight data supporting its use following surgically induced remission of CD. Evidence supporting the use of mesalamine as prophylaxis for colorectal cancer and dysplasia will be considered. Finally, recent developments in our understanding of how to use modified release mesalamine in a safe and cost-effective manner are evaluated, including discussion of the importance of studying patient non-adherence as a key component of future studies in this area.

An open-label prospective randomized multicenter study shows very rapid remission of ulcerative colitis by intensive granulocyte and monocyte adsorptive apheresis as compared with routine weekly treatment

OBJECTIVES

Granulocyte and monocyte adsorptive apheresis (GMA) has shown efficacy in patients with active ulcerative colitis (UC). However, with routine weekly treatment, it may take several weeks to achieve remission, and to date, the efficacy of a more frequent treatment schedule remains unknown. The aim of this study was to assess the clinical efficacy and safety of intensive GMA treatment in patients with active UC.

METHODS

This was an open-label, prospective, randomized multicenter study to compare an intensive, two GMA sessions per week, with the routine, one GMA session per week. A total of 163 patients with mild-to-moderately active UC were randomly assigned to routine weekly treatment or intensive treatment. The maximum number of sessions of GMA permitted was 10. However, when patients achieved remission, GMA was discontinued. Remission rate at the end of the study, time to remission, and adverse events were assessed in both groups.

RESULTS

Of the 163 patients, 149 were available for efficacy analysis as per protocol, 76 were in weekly GMA, and 73 were in intensive GMA. At the end of the study period, clinical remission was achieved in 41 of 76 patients (54.0%) in weekly GMA and in 52 of 73 patients (71.2%) in intensive GMA (P=0.029). The mean time to remission was 28.1+/-16.9 days in the weekly GMA treatment group and 14.9+/-9.5 days in the intensive GMA group (P<0.0001). Intensive GMA was well tolerated without GMA-related serious adverse side effects.

CONCLUSIONS

Intensive GMA in patients with active UC seems to be more efficacious than weekly treatment, and significantly reduced the patients' morbidity time without increasing the incidence of side effects.

Effect of mesalazine on mucosal immune biomarkers in irritable bowel syndrome: a randomized controlled proof-of-concept study

BACKGROUND

Intestinal immune infiltration contributes to symptoms in patients with irritable bowel syndrome (IBS).

AIM

To assesses the effect of mesalazine (mesalamine) on mucosal immune cells in patients with IBS, through a pilot study.

METHODS

A randomized, double-blind, placebo-controlled trial in 20 patients with IBS in tertiary care setting. Patients were randomized to receive placebo or 800 mg mesalazine three times daily for 8 weeks. The primary endpoint was a significant reduction in total colonic immune cells on biopsies obtained at the end of treatment compared to baseline. Secondary endpoints included effects on subsets of immune cells, inflammatory mediators and symptom severity. Intention-to-treat analysis was performed.

RESULTS

Mesalazine markedly reduced immune cells as compared with placebo (P = 0.0082); this effect was ascribed to a marked inhibition of mast cells (P = 0.0014). Mesalazine significantly increased general well-being (P = 0.038), but had no significant effects on abdominal pain (P = 0.084), bloating (P = 0.177) or bowel habits. No serious drug-related adverse events were reported during the study.

CONCLUSIONS

Mesalazine is an effective and safe approach to reduce mast cell infiltration and may improve general well-being in patients with IBS. These results support the hypothesis that immune mechanisms represent potential therapeutic targets in IBS.

Review article: 5-aminosalicylate formulations for the treatment of ulcerative colitis--methods of comparing release rates and delivery of 5-aminosalicylate to the colonic mucosa

BACKGROUND

Many oral 5-aminosalicylic acid (5-ASA) formulations are designed to maximize 5-ASA release in the colon where it acts topically on the colonic mucosa. Delayed-release formulations and azo-prodrugs minimize 5-ASA absorption in the upper gastrointestinal (GI) tract.

AIMS

To review methods for assessing 5-ASA release and colonic distribution from oral formulations, and the potential use of this information for guiding clinical decisions.

METHODS

PubMed and recent conference abstracts were searched for articles describing techniques used to assess 5-ASA release from ulcerative colitis (UC) therapies.

RESULTS

In-vitro GI models, although unable to simulate more complex aspects of GI physiology, can provide useful data on 5-ASA release kinetics and bioaccessibility. Gamma-scintigraphy is useful for investigating GI disintegration of different formulations, but may not accurately reflect 5-ASA distribution. Plasma pharmacokinetic studies provide data on systemic exposure, but not on colonic distribution or mucosal uptake. Mucosal biopsies provide direct evidence of colonic distribution and may predict clinical efficacy, but must be interpreted cautiously because of considerable inter-subject variability and other confounding factors.

CONCLUSION

While assessment of 5-ASA release is important, limitations of individual measurement techniques mean that randomized clinical studies in UC patients remain the best guide for dosing and treatment regimen decisions.

Improving delivery of aminosalicylates in ulcerative colitis: effect on patient outcomes

Developments in drug delivery technology have expanded the formulations of 5-aminosalicylic acid (5-ASA) available to clinicians over the last 50 years. Delivery of adequate doses of 5-ASA to the colon can be achieved by pH-dependent, delayed-release or pro-drug formulations. Despite some variations in the pharmacokinetics between individual preparations, the clinical effects in induction of response and maintenance of remission in ulcerative colitis appear to be consistent. Direct comparison studies between different preparations have yielded similar results in primary endpoints, although differences in secondary endpoints or post hoc analyses have been noted. The development of delivery methods that allow once-daily administration represents a potential means to improve the low medication adherence rates reported in patients with ulcerative colitis.

Mesalamine with MMX technology for the treatment of ulcerative colitis

Mesalamine with MMX Multi Matrix System technology (hereafter referred to as MMX mesalamine) is an oral, high-strength (1.2 g/tablet), once-daily formulation of 5-aminosalicylic acid used for the treatment of ulcerative colitis. This new formulation has been designed to provide delayed and prolonged 5-aminosalicylic acid release throughout the colon. In recent clinical studies, MMX mesalamine (taken as a once-daily dose of 2.4 or 4.8 g) effectively induced clinical remission and mucosal healing versus placebo in patients with active, mild-to-moderate ulcerative colitis. Once remission was achieved, MMX mesalamine effectively maintained disease remission in the majority of patients for at least 12 months. In this paper, we comprehensively review the results of studies exploring the clinical pharmacology, efficacy and safety of MMX mesalamine in patients with ulcerative colitis, and examine the implications of these findings on clinical practice.

Oral 5-ASA therapy in ulcerative colitis: what are the implications of the new formulations?

5-aminosalicylic acid (5-ASA) is the standard first-line treatment for mild-to-moderate ulcerative colitis. A variety of 5-ASA delivery systems are available and in development, including both oral and rectal formulations; all of which aim to deliver the active drug to the colon while minimizing systemic absorption. Because the efficacy of most oral 5-ASA therapies is broadly similar, the appropriate selection of a given formulation often relies on other factors. This article explores the differences between oral 5-ASA formulations in terms of their delivery system, reviews the available data on oral 5-ASA treatment efficacy and tolerability, and examines the rationale for changing from one 5-ASA formulation to another if a patient does not respond to, or worsens on, their existing agent.

Effect of mesalamine on healing in experimental colon anastomosis: a randomised experimental study

OBJECTIVE

We aimed to investigate the effect of mesalamine on healing of experimental colon anastomosis model.

MATERIAL/METHODS

Forty adult male Wistar albino rats were performed segmentary colonic resection and end-to-end anastomosis. Animals were randomly divided into four groups: group I, anastomosis group, received no treatment (GI, n=8); group II, anastomosis+oral mesalamine group (100mg/kg/day); group III, anastomosis+rectal mesalamine (2mL) group, (GIII, n=8); group IV, anastomosis+oral mesalamine+rectal mesalamine (GIV, n=8) group. A sham group (n=8) was constituted and was performed laparotomy. Bursting pressure, hydroxyproline levels and histopathological characteristics of the anastomosis were analyzed.

RESULTS

Although it was not statistically significant, there was an increase in the burst pressure of the mesalamine group. When hydroxyproline measurements were compared there were statistically significant difference between the non-treated colon and all groups. There were significant differences between GI and GIII-GIV, GII and GIV. The differences between group I and II and group II and III were not statistically significant. When we compared the median amount of the histopathological changes, we found significant difference between the anastomosis and the mesalamine groups (P<0.05). But when mesalamine groups were compared with each other we did not observe a significant difference.

CONCLUSION

Mesalamine had positive effects which were not statistically significant on bursting pressure and statistically different significant effects on hydroxyproline (HP) levels based on the way of administration and statistically significant positive effects on histopathologic anastomotic healing in experimental anastomosis model.

Effectiveness of mesalamine and propolis in experimental colitis

This study was conducted to investigate the effects of propolis and mesalamine on experimental colitis in rats. Distal colitis was induced in rats by intracolonic instillation of 2 mL of 4% acetic acid. The animals were randomly assigned to 5 groups: group 1, control, (n=8); group 2, colitis, received no treatment (n=8); group 3, colitis+mesalamine, 2 mL once a day via an enema (n=8); group 4, colitis+propolis, 600 mg/kg once a day via intragastric lavage (n=8); and group 5, colitis+mesalamine+propolis for 1 wk (n=8). Levels of nitric oxide were statistically significantly different in comparisons between groups 1 and 2, groups 2 and 3, and groups 4 and 5. Malondialdehyde levels were significantly different when group 2 was compared with groups 3, 4, and 5. A significant difference was observed when group 3 was compared with group 4 for myeloperoxidase. Most propolis-treated rats had normal histology; mesalamine-treated and propolis+mesalamine-treated rats had inflammatory cell infiltration at rates of 50% and 33%, respectively. The investigators concluded that propolis and mesalamine are efficient independently and in combination, but that their combined effect was not observed to be additive in experimental colitis.

Systemic and local cytokine production in quiescent ulcerative colitis and its relationship to future relapse: a prospective pilot study

BACKGROUND

The main aim of this prospective study was to examine whether systemic (plasma) and local (mucosal) cytokine production is a predictor of future relapse in patients with quiescent ulcerative colitis (UC). The impact of other clinical and laboratory parameters on relapse was also studied.

METHODS

Fifty consecutive patients with quiescent UC were included. At enrollment, blood and mucosal (rectal biopsies) samples were collected. All patients were followed up regularly for 1 year after enrollment. Plasma and mucosal cytokine levels were measured by enzyme-linked immunosorbent assay. To identify independent significant predictive factors for relapse, time-dependent analyses using the Kaplan-Meier method and the Cox proportional hazard model were performed.

RESULTS

Thirty-four patients remained in remission, and 16 patients relapsed during the 1-year follow-up. Higher interleukin (IL)-8 levels in the rectal mucosa were significantly associated with relapse. In contrast, IL-1beta, IL-6, and tumor necrosis factor-alpha levels in the rectal mucosa were not associated with relapse. Conventional blood markers and plasma cytokines (IL-1beta, IL-6, IL-8, and tumor necrosis factor-alpha) did not correlate with relapse. Among clinical factors, age and number of prior relapses were significantly associated with relapse. In multivariate analysis, a higher rectal mucosal IL-8 level (> or = 160 pg/mg of tissue; hazard ratio, 4.7), younger age (<30 yr; hazard ratio, 7.3), and a greater number of prior relapses (> or = 5; hazard ratio, 4.3) were independent significant risk factors for future relapse.

CONCLUSIONS

Rectal mucosal IL-8 measurement might be an additional objective diagnostic tool that can predict relapse in patients with quiescent UC.

Postoperative change of mucosal inflammation at strictureplasty segment in Crohn's disease: cytokine production and endoscopic and histologic findings

PURPOSE

This study was designed to examine postoperative change of mucosal inflammation at strictureplasty segment in Crohn's disease mainly by cytokine measurements.

METHODS

Patients who underwent strictureplasty for Crohn's disease in the terminal ileum were investigated. Mucosal samples at the strictureplasty site were obtained during operation. At 3, 6, and 12 months after operation, biopsy specimens were taken from the strictureplasty site and macroscopically normal ileum at endoscopy. Mucosal cytokine concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

The mucosal concentrations of proinflammatory cytokines (interleukin-1beta, interleukin-6, interleukin-8, and tumor necrosis factor-alpha) and anti-inflammatory mediator (interleukin-1 receptor antagonist) at the strictureplasty segment greatly increased at the time of operation. Interleukin-1beta, interleukin-1 receptor antagonist, interleukin-6, interleukin-8, and tumor necrosis factor-alpha concentrations at the strictureplasty segment decreased during a 12-month period after operation. Twelve months after operation there was no significant difference in each cytokine concentration between the strictureplasty and macroscopically normal segments. The mucosal interleukin-1 receptor antagonist/interleukin-1beta ratio at the strictureplasty segment increased during a 12-month period after operation. Twelve months after operation there was no significant difference in the ratio between the strictureplasty and macroscopically normal segments. The endoscopic and histologic severities of mucosal inflammation at the strictureplasty site also decreased; however, their findings were not normalized during the study.

CONCLUSIONS

During one year after strictureplasty for Crohn's disease, cytokine production at the strictureplasty segment was decreased to the level of the macroscopically normal ileum and an imbalance between proinflammatory and antiinflammatory cytokines was corrected.

A double-blind dose-escalating trial comparing novel mesalazine pellets with mesalazine tablets in active ulcerative colitis

BACKGROUND

Mesalazine as the treatment standard for ulcerative colitis can be applied in different galenical preparations.

AIM

A novel formulation of mesalazine pellets with delayed and prolonged release characteristics was compared with conventional Eudragit L-coated tablets. Furthermore, the effect of mesalazine dose escalation on nonresponders was evaluated in both treatment groups.

METHODS

A total of 233 patients with mild to moderately active ulcerative colitis were randomized to receive either mesalazine (1.5 g/day in three doses) as pellets (n = 115) or tablets (n = 118) for 8 weeks. At insufficient response, the dose was increased to 3.0 g.

RESULTS

The clinical remission rate (clinical activity index < or = 4) for pellets was 67% vs. 68% for tablets which statistically proved to be not inferior (significance level alpha = 2.5%). In patients without dose increase, the remission rate was 47% (pellets) vs. 42% (tablets). Endoscopic improvement was observed in 80% (pellets) vs. 83% (tablets), and histological improvement in 48% (pellets) vs. 52% (tablets) of patients.

CONCLUSIONS

Mesalazine pellets are as effective as tablets in the treatment of mild to moderately active ulcerative colitis. Dose escalation to 3.0 g/day is a valid option for nonresponders to a starting dose of 1.5 g/day.

Mesalamine delivery systems: do they really make much difference?

Sulfasalazine's role as the first-line of therapy in patients with inflammatory bowel disease has led to the development of other "designer" aminosalicylates, which eliminate the sulfa-moiety, and attempt to target the topically active mesalamine to the inflamed bowel. Olsalazine sodium and balsalazide disodium utilize the same azo-bond structure as sulfasalazine, requiring release of active mesalamine by colonic bacteria, and thus targeting these agents to the colon. Other mesalamine delivery systems use pH-dependant- or moisture-release to liberate the active mesalamine in both the large and small bowel. Direct application of mesalamine via enema or suppository is also effective in patients with distal colitis. The pharmacology and thus the undesirable drug absorption rates differ between drugs, although the clinical importance of these characteristics is debatable. Differences in release-systems, the impact of the fed and fasting state, and unique patient intolerances to individual agents demand an understanding of each of these products, and their application to patient therapy.

Mesalamine induces manganese superoxide dismutase in rat intestinal epithelial cell lines and in vivo

Mesalamine (5-ASA) is effective in the treatment of inflammatory bowel diseases. However, the mechanisms of action of 5-ASA remain unclear. IEC-6 and IRD-98, nontransformed rat small intestinal epithelial cell lines, were used to examine the effect of 5-ASA on the expression of manganese superoxide dismutase (MnSOD). Rats were given 5-ASA enemas to determine the effect on colonic MnSOD expression. Treatment with 5-ASA at 0.02 or 2 mg/ml induced MnSOD mRNA levels 2.67-fold or 5.66-fold, respectively. Inhibition of 5-lipoxygenase activating protein with MK-886 or cyclooxygenase with indomethacin did not influence the level of MnSOD mRNA. Nuclear run-on experiments demonstrated an increase in de novo transcription following treatment with 5-ASA. MnSOD protein levels were induced 2-fold at 24 h and 4.23-fold at 48 h following treatment with 1 mg/ml 5-ASA. 5-ASA increased MnSOD 1.7-fold in vivo. Pretreatment with 5-ASA significantly protected IRD-98 cells from tumor necrosis factor-alpha cytotoxicity. This is the first example of transcriptional gene regulation by 5-ASA. The induction of MnSOD by 5-ASA may contribute to the therapeutic mechanism of 5-ASA.

Inhibition of platelet activation by 5-aminosalicylic acid in inflammatory bowel disease

BACKGROUND

Platelets play an important role in inflammation and are activated in inflammatory bowel disease. Micro-vascular thrombosis in the gut wall leading to intestinal micro-infarction may be a pathogenic feature of Crohn's disease. 5-Aminosalicylic acid is an effective treatment for patients with inflammatory bowel disease.

AIMS

To assess the effects of 5-aminosalicylic acid on platelet activation, when taken orally and in vitro by patients with inflammatory bowel disease.

METHODS

Spontaneous and thrombin-induced platelet activation were studied using fluorescent antibodies to the activated platelet surface glycoprotein P-selectin and flow cytometry.

RESULTS

Baseline platelet activation in inflammatory bowel disease was significantly greater than that in controls (P=0.0003). Independent of diagnosis or disease activity, spontaneous ex-vivo platelet activation was 50% lower in patients with inflammatory bowel disease taking 5-aminosalicylic acid orally than in those not on such treatment (P < 0.05). In vitro, 5-aminosalicylic acid significantly reduced both spontaneous (P < 0. 03 for >/=1 microM 5-aminosalicylic acid) and thrombin-induced platelet activation (P < 0.02 for >/= 1 microM 5-aminosalicylic acid).

CONCLUSIONS

5-Aminosalicylic acid given either orally or in vitro inhibits platelet activation. If this effect reflects an in vivo action in the gut, it could contribute to the beneficial actions of 5-aminosalicylic acid in inflammatory bowel disease.

Intestinal anti-inflammatory activity of UR-12746, a novel 5-ASA conjugate, on acute and chronic experimental colitis in the rat

The present study was undertaken to investigate the intestinal anti-inflammatory effects of UR-12746 on the acute and chronic stages of a trinitrobenzene sulphonic acid (TNBS) experimental model of inflammatory bowel disease (IBD) in the rat. UR-12746 is a novel, locally-acting compound which combines, through an azo bond, 5-aminosalicylic (5-ASA) and UR-12715, a potent platelet activating factor (PAF)-antagonist. UR-12746 oral pretreatment of colitic rats (50 and 100 mg kg(-1)) reduced acute colonic damage when evaluated 2 days after colonic insult. Postreatment for 4 weeks with UR-12746 (50 and 100 mg kg(-1)) resulted in a faster recovery of the damaged colonic mucosa, which was macroscopically significant from the third week. The intestinal anti-inflammatory effect of UR-12746 was associated with a decrease in leukocyte infiltration in the colonic mucosa, which was evidenced both biochemically, by a reduction in myeloperoxidase activity, and histologically, by a lower leukocyte count after morphometric analysis. This effect was higher than that seen with sulphasalazine, when assayed at the same doses and in the same experimental conditions. Several mechanisms can be involved in the beneficial effects showed by UR-12746: inhibition of leukotriene B(4) synthesis in the inflamed colon, improvement of the altered colonic oxidative status, and reduction of colonic interleukin-1beta production. The results suggest that the intestinal anti-inflammatory activity of UR-12746 can be attributed to the additive effects exerted by 5-ASA and UR-12715, the PAF antagonist compound, that are released in the colonic lumen after reduction of the azo bond by the intestinal bacteria.

Prolonged-release mesalazine: a review of its therapeutic potential in ulcerative colitis and Crohn's disease

Prolonged-release mesalazine (Pentasa) consists of ethylcellulose-coated microgranules from which mesalazine (known in the US as mesalamine) is released in the small and large intestine in a diffusion-dependent manner. Dose-dependent improvements in clinical and endoscopic parameters have been reported with prolonged-release mesalazine 2 and 4 g/day in clinical trials in patients with mild to moderately active ulcerative colitis. Induction of clinical and endoscopic remission was achieved in more patients receiving a daily dosage of 4 g/day than in those receiving placebo. In patients with ulcerative colitis in remission, prolonged-release mesalazine is effective in reducing the rate of relapse. Higher dosages tend to be more effective, and a 12-month remission rate of 64% has been reported for patients treated with a 4 g daily dosage of this formulation. Comparative data indicate that prolonged-release mesalazine has similar efficacy in maintaining remission to molar equivalent doses of sulfasalazine. Data from a study in patients with mild to moderately active Crohn's disease indicates that higher dosages (4 g/day) of prolonged-release mesalazine are more effective than placebo in reducing disease activity. After 16 weeks' treatment, 64% of patients receiving a 4 g/day dosage experienced clinical improvement and 43% attained remission. In studies of patients in remission of Crohn's disease, the formulation appears to be more effective in preventing relapse in patients with isolated small bowel disease than in those with colonic involvement. The tolerability profile of oral prolonged-release mesalazine is similar to that of placebo and the incidence of adverse events does not appear to be dose-related. Nausea/vomiting, diarrhoea, abdominal pain and dyspepsia occur most frequently, although their incidence is low. Reports of nephrotoxicity during prolonged-release mesalazine treatment are rare.

CONCLUSIONS

Oral prolonged-release mesalazine is effective for maintenance and induction of remission of mild to moderately active colitis, both in patients with distal disease and in those with pancolitis. The formulation has similar efficacy to that of equimolar concentrations of sulfasalazine. Prolonged-release mesalazine also appears to be effective in the treatment of Crohn's disease, and maintenance therapy is of particular value in patients with isolated small bowel involvement. Evidence suggests that higher dosages (3 to 4 g/day) of prolonged-release mesalazine have additional therapeutic benefits over lower dosages in patients with inflammatory bowel disease without increasing the incidence of adverse events.

Antioxidant effects of aminosalicylates and potential new drugs for inflammatory bowel disease: assessment in cell-free systems and inflamed human colorectal biopsies

BACKGROUND

The therapeutic efficacy of 5-aminosalicylic acid in inflammatory bowel disease may be related to its antioxidant properties.

AIM

To compare in vitro the antioxidant effects of conventional drugs (5-aminosalicylic acid, corticosteroids, metronidazole), with new aminosalicylates (4-aminosalicylic acid, balsalazide) and other potential therapies (ascorbate, N-acetylcysteine, glutathione, verapamil).

METHODS

Compounds were assessed for efficacy in reducing the in vitro production of reactive oxygen species by cell-free systems (using xanthine/xanthine oxidase, with or without myeloperoxidase) and by colorectal biopsies from patients with ulcerative colitis using luminol-amplified chemiluminescence.

RESULTS

5-aminosalicylic acid and balsalazide were more potent antioxidants than 4-aminosalicylic acid or N-acetyl-5-aminosalicylic acid in cell-free systems. 5-aminosalicylic acid (20 mM) and balsalazide (20 mM) inhibited rectal biopsy chemiluminescence by 93% and 100%, respectively, compared with only 59% inhibition by 4-aminosalicylic acid (20 mM). Hydrocortisone, metronidazole and verapamil had no significant effect on chemiluminescence in any system. Ascorbate (20 mM) inhibited chemiluminescence by 100% in cell-free systems and by 60% in rectal biopsies. N-acetyl cysteine (10 mM), and both oxidized and reduced glutathione (10 mM), completely inhibited chemiluminescence in cell-free systems, but not with rectal biopsies.

CONCLUSIONS

The antioxidant effects of compounds varies between cell-free systems and inflamed colorectal biopsies. The effect of drugs on the chemiluminescence produced by these two assay systems is useful for screening potentially new antioxidant treatments for inflammatory bowel disease. Ascorbate seems worth further study as a novel therapy.

Oral delayed-release mesalazine: a review of its use in ulcerative colitis and Crohn's disease

Oral delayed-release mesalazine is an enteric-coated formulation which releases mesalazine in the terminal ileum and colon. Up to 74% of patients with mild to moderately active ulcerative colitis experience endoscopic or symptomatic improvement (including remission) or both when treated with oral delayed-release mesalazine 2.4 to 4.8 g/day. There is a trend towards a better response in patients receiving higher daily dosages of oral delayed-release mesalazine, especially in patients with active distal disease. In patients with left-sided ulcerative colitis, oral balsalazide 6.75 g/day appears to be more effective than oral delayed-release mesalazine 2.4 g/day, but a higher dosage of oral delayed-release mesalazine 4.8 g/day may provide additional benefit in these patients. Oral delayed-release mesalazine 0.8 to 4.4 g/day appears to be as effective as sulfasalazine 2 to 4 g/day, prolonged-release mesalazine 1.5 g/day or balsalazide 3 g/day in maintaining remission in patients with ulcerative colitis. The optimal dosage of oral delayed-release mesalazine for the maintenance of remission is unclear. However, oral delayed-release mesalazine 1.6 g/day with rectal mesalazine 4g, administered twice weekly, was more effective than oral drug alone in maintaining remission in patients at high risk of relapse. In patients with left-sided or distal disease oral olsalazine 1 g/day appeared to be superior to oral delayed-release mesalazine 1.2 g/day for maintenance of symptomatic remission. Limited data in patients with Crohn's disease have shown oral delayed-release mesalazine 0.4 to 4.8 g/day to be an effective therapy for active disease (remission in up to 45% of patients) and for quiescent disease (relapse in 34% of recipients over a duration of up to 12 months). Preliminary data indicate that oral delayed-release mesalazine 2.4 g/day is effective in preventing postoperative recurrence of Crohn's disease. Oral delayed-release mesalazine is effective and well tolerated in sulfasalazine-intolerant patients with ulcerative colitis or Crohn's disease.

CONCLUSIONS

Oral delayed-release mesalazine is effective in patients with mild to moderately active or quiescent ulcerative colitis. Available data suggest that patients with left-sided or distal ulcerative colitis are likely to require higher daily dosages of oral delayed-release mesalazine or supplementation with rectal mesalazine. Oral delayed-release mesalazine also appears to be effective in active and quiescent Crohn's disease. The drug is well tolerated and it appears to be effective in sulfasalazine-intolerant patients.

Antioxidants inhibit the in vitro production of inflammatory cytokines in Crohn's disease and ulcerative colitis

BACKGROUND

Modulation of cytokine secretion may be of interest in the treatment of Crohn's disease or ulcerative colitis.

METHODS

The effect of three antioxidants - butylated hydroxyanisol, tetrahydropapaveroline and nordihydroguaiaretic acid - on the production of tumour necrosis factor (TNF), interleukin (IL) 1, IL-6 and IL-8 (measured by enzyme-linked immunosorbent assay) by peripheral mononuclear cells and biopsies of inflamed colonic mucosa from inflammatory bowel disease patients were studied.

RESULTS

We observed a decrease in IL-1 and IL-6 production by peripheral mononuclear cells from inflammatory bowel disease patients (approximately 50% of control). The three drugs did not decrease IL-6 and IL-8 secretion by colonic biopsies, whereas they did inhibit IL-1 and, to some degree, TNF production. The cytokine-inhibitory effect of antioxidants seems to be more pronounced in ulcerative colitis than in Crohn's disease.

CONCLUSION

Our results suggest that the studied antioxidants, or related compounds, may be of interest in inflammatory bowel disease treatment.

The mechanisms of action of disease-modifying antirheumatic drugs: a review with emphasis on macrophage signal transduction and the induction of proinflammatory cytokines

1. Rheumatoid arthritis (RA) is probably the most common source of treatable disability. A major problem in modern rheumatology is that the mechanism(s) of action of the currently used disease-modifying antirheumatic drugs (DMARDs) remain unclear. Many of these drugs entered rheumatology mainly through clinical intuition and have been used for decades. 2. The former T-cell-centered paradigm of rheumatoid inflammation has given way to a model of inflammation highlighting the macrophage and its proinflammatory cytokines. In particular, tumor necrosis factor alpha (TNF-alpha) has gained prominence as a central proinflammatory mediator in RA, and antibodies against TNF-alpha have been successfully used in patients with RA. 3. This review will summarize the recent advances in determining the mechanisms of action of the currently used DMARDs, with particular emphasis on their effects on the induction of TNF-alpha and interleukin 1 (IL-1) in mononuclear phagocytes. Although some DMARDs, such as auranofin, antimalarials and tenidap, act as inhibitors of the induction of these cytokines in monocytes or macrophages or both, other drugs, such as methotrexate, D-penicillamine and aurothiomalate, do not seem to affect either TNF-alpha or IL-1. 4. The drugs' effects on proinflammatory cytokine induction are correlated to those on other macrophage responses.

Mucosal interleukin-6 secretion in ulcerative colitis. Effects of anti-inflammatory drugs and T-cell stimulation

BACKGROUND

We have studied modulation of mucosal interleukin-6 (IL-6) secretion by T-cell activation and by anti-inflammatory agents in inflammatory bowel disease.

METHODS

In vitro secretion of IL-6 by biopsy specimens from patients with active ulcerative colitis was investigated in the presence of cyclosporin-A (CsA) and drugs that have other anti-inflammatory actions. Biopsy specimens from patients with quiescent ulcerative colitis or controls were stimulated with anti-CD3 antibody to activate mucosal T cells.

RESULTS

Stimulation of control specimens increased IL-6 secretion (median increase, 147%; p < 0.003), which was prevented by CsA. In quiescent ulcerative colitis there was enhanced spontaneous secretion of IL-6 but a smaller, non-significant increase after T-cell activation (125%). Dexamethasone inhibited secretion in active ulcerative colitis (p < 0.006). 5-Aminosalicylic acid, 6-mercaptopurine, methotrexate, and indomethacin had no effect. There also tended to be a small reduction with CsA, but this just failed to reach statistical significance.

CONCLUSIONS

In quiescent ulcerative colitis the enhanced spontaneous secretion of IL-6 may be a consequence of mucosal T-cell or macrophage activation: the smaller increase after T-cell stimulation suggests that one or both of these two cell types are already pre-activated.

Salicylates for ulcerative colitis--their mode of action

Delivery of 5-aminosalicylic acid to the colon by sulphasalazine, other azo-bonded compounds and controlled-release preparations is introduced in the context of metabolism by epithelial cells and therapeutic efficacy in ulcerative colitis. Potential modes of action are then reviewed, including actions on luminal bacteria, epithelial cell surface receptors, cellular events (such as nitric oxide release or butyrate oxidation), electrolyte transport and epithelial permeability. Evidence for an influence of salicylates on circulating and lamina propria inflammatory cells is presented, as well as actions on adhesion molecules, chemotactic peptides and inflammatory mediators, such as eicosanoids, platelet-activating factor, cytokines or reactive oxygen metabolites. The precise mechanism will remain uncertain as long as the aetiology of ulcerative colitis is unknown, but a pluripotential mode of action of salicylates is an advantage when influencing the network of events that constitute chronic inflammation.

Aetiology and pathogenesis of chronic inflammatory bowel disease

While Crohn's disease and ulcerative colitis are both conditions characterized by intestinal inflammation, with some overlap in their clinical and histological features, they are essentially different in pathogenesis. Crohn's disease appears to be primarily a condition of chronic T-lymphocyte activation, with tissue damage induced by secondary macrophage activation. What activates the T-cells is unknown. In this chapter we look at the evidence for and against cell-wall deficient mycobacteria species, viral infection of vascular endothelium and luminal contents as potential mechanisms of chronic activation. In ulcerative colitis, by contrast, there is no strong evidence for T-cell activation, and humoral mechanisms predominate. While the finding of atypical anti-neutrophil cytoplasmic antibodies (P-ANCAs) may be useful in screening, the only novel pathogenetic discovery is the co-localization of a 40 kD colonic autoantibody with immunoglobulins and complement on the apical enterocyte surface. Despite the fundamental differences in initiating mechanisms, the two conditions have many 'downstream' inflammatory processes in common. We discuss the evidence for local production of cytokines, arachidonic acid metabolites and reactive oxygen and nitrogen radicals, highlighting the potential adverse consequences for intestinal vascular integrity.

Review article: the mode of action of the aminosalicylates in inflammatory bowel disease

Sulphasalazine and other 5-aminosalicylic acid (5-ASA)-containing drugs are used in the treatment of acute inflammatory bowel disease and in the maintenance of clinical remission. Despite their use for over 50 years, the mechanism of action of this class of drugs remains uncertain, although a number of possibilities are discussed in this review. It seems likely that the aminosalicylates are important free radical scavengers, can reduce leukotriene production and can inhibit the cellular release of interleukin-1, all of which are likely to be important in reducing the acute inflammatory response in inflammatory bowel disease. The effects of these drugs on prostaglandin production are more contentious, but it appears that 10(-5) to 10(-4) M concentrations stimulate production of prostaglandins which may be cytoprotective, while higher doses of these drugs inhibit prostaglandin production. The aminosalicylates may maintain remission in inflammatory bowel disease by preventing leucocyte recruitment into the bowel wall. The drugs inhibit the chemotactic response to leukotriene B4, reduce the synthesis of platelet activating factor and also inhibit leucocyte adhesion molecule upregulation.