N-acetyl-L-cysteine combined with mesalamine in the treatment of ulcerative colitis: Randomized, placebo-controlled pilot study

Enhancement of efferocytosis through biased FPR2 signaling attenuates intestinal inflammation

Efficient clearance of dying cells (efferocytosis) is an evolutionarily conserved process for tissue homeostasis. Genetic enhancement of efferocytosis exhibits therapeutic potential for inflammation resolution and tissue repair. However, pharmacological approaches to enhance efferocytosis remain sparse due to a lack of targets for modulation. Here, we report the identification of columbamine (COL) which enhances macrophage-mediated efferocytosis and attenuates intestinal inflammation in a murine colitis model. COL enhances efferocytosis by promoting LC3-associated phagocytosis (LAP), a non-canonical form of autophagy. Transcriptome analysis and pharmacological characterization revealed that COL is a biased agonist that occupies a part of the ligand binding pocket of formyl peptide receptor 2 (FPR2), a G-protein coupled receptor involved in inflammation regulation. Genetic ablation of the Fpr2 gene or treatment with an FPR2 antagonist abolishes COL-induced efferocytosis, anti-colitis activity and LAP. Taken together, our study identifies FPR2 as a potential target for modulating LC3-associated efferocytosis to alleviate intestinal inflammation and highlights the therapeutic value of COL, a natural and biased agonist of FPR2, in the treatment of inflammatory bowel disease.

Potential Use of Antioxidant Compounds for the Treatment of Inflammatory Bowel Disease

Since inflammatory bowel diseases (IBDs) are chronic, the development of new effective therapeutics to combat them does not lose relevance. Oxidative stress is one of the main pathological processes that determines the progression of IBD. In this regard, antioxidant therapy seems to be a promising approach. The role of oxidative stress in the development and progression of IBD is considered in detail in this review. The main cause of oxidative stress in IBD is an inadequate response of leukocytes to dysbiosis and food components in the intestine. Passage of immune cells through the intestinal barrier leads to increased ROS concentration and the pathological consequences of exposure to oxidative stress based on the development of inflammation and impaired intestinal permeability. To combat oxidative stress in IBD, several promising natural (curcumin, resveratrol, quercetin, and melatonin) and artificial antioxidants (N-acetylcysteine (NAC) and artificial superoxide dismutase (aSOD)) that had been shown to be effective in a number of clinical trials have been proposed. Their mechanisms of action on pathological events in IBD and clinical manifestations from their impact have been determined. The prospects for the use of other antioxidants that have not yet been tested in the treatment of IBD, but have the properties of potential therapeutic candidates, have been also considered.

Extraintestinal Manifestations in Induced Colitis: Controversial Effects of N-Acetylcysteine on Colon, Liver, and Kidney

Ulcerative colitis (UC) is a chronic and recurrent inflammatory bowel disease (IBD) characterized by continuous inflammation in the colonic mucosa. Extraintestinal manifestations (EIM) occur due to the disruption of the intestinal barrier and increased permeability caused by redox imbalance, dysbiosis, and inflammation originating from the intestine and contribute to morbidity and mortality. The aim of this study is to investigate the effects of oral N-acetylcysteine (NAC) on colonic, hepatic, and renal tissues in mice with colitis induced by dextran sulfate sodium (DSS). Male Swiss mice received NAC (150 mg/kg/day) in the drinking water for 30 days before and during (DSS 5% v/v; for 7 days) colitis induction. On the 38th day, colon, liver, and kidney were collected and adequately prepared for the analysis of oxidative stress (superoxide dismutase (SOD), catalase (CAT), glutathione reduced (GSH), glutathione oxidized (GSSG), malondialdehyde (MDA), and hydrogen peroxide (H2O2)) and inflammatory biomarkers (myeloperoxidase (MPO) -, tumor necrosis factor alpha - (TNF-α, and interleukin-10 (IL-10)). In colon, NAC protected the histological architecture. However, NAC did not level up SOD, in contrast, it increased MDA and pro-inflammatory effect (increased of TNF-α and decreased of IL-10). In liver, colitis caused both oxidative (MDA, SOD, and GSH) and inflammatory damage (IL-10). NAC was able only to increase GSH and GSH/GSSG ratio. Kidney was not affected by colitis; however, NAC despite increasing CAT, GSH, and GSH/GSSG ratio promoted lipid peroxidation (increased MDA) and pro-inflammatory action (decreased IL-10). Despite some beneficial antioxidant effects of NAC, the negative outcomes concerning irreversible oxidative and inflammatory damage in the colon, liver, and kidney confirm the nonsafety of the prophylactic use of this antioxidant in models of induced colitis, suggesting that additional studies are needed, and its use in humans not yet recommended for the therapeutic routine of this disease.

Personalized redox medicine in inflammatory bowel diseases: an emerging role for HIF-1α and NRF2 as therapeutic targets

Inflammatory bowel diseases (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), are intimately associated with inflammation and overproduction of reactive oxygen species (ROS). Temporal and inter-individual variabilities in disease activity and response to therapy pose significant challenges to diagnosis and patient care. Discovery and validation of truly integrative biomarkers would benefit from embracing redox metabolomics approaches with prioritization of central regulatory hubs. We here make a case for applying a personalized redox medicine approach that aims to selectively inhibit pathological overproduction and/or altered expression of specific enzymatic sources of ROS without compromising physiological function. To this end, improved 'clinical-omics integration' may help to better understand which particular redox signaling pathways are disrupted in what patient. Pharmacological interventions capable of activating endogenous antioxidant defense systems may represent viable therapeutic options to restore local/systemic redox status, with HIF-1α and NRF2 holding particular promise in this context. Achieving the implementation of clinically meaningful mechanism-based biomarkers requires development of easy-to-use, robust and cost-effective tools for secure diagnosis and monitoring of treatment efficacy. Ultimately, matching redox-directed pharmacological interventions to individual patient phenotypes using predictive biomarkers may offer new opportunities to break the therapeutic ceiling in IBD.

Effects of N-acetylcysteine supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in rheumatoid arthritis patients: a randomized double-blind placebo-controlled trial

Considering the importance of inflammation and oxidative stress in the development of rheumatoid arthritis (RA) as well as anti-inflammatory and antioxidant features of N-acetylcysteine (NAC), this study was conducted to evaluate the effect of NAC supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in RA patients. In a randomized double-masked placebo-controlled trial, 74 RA subjects were chosen and randomly divided into two groups to take 600 mg of NAC or placebo twice daily for 3 months. Before and after the study, disease activity was assessed via disease activity score-28 (DAS-28), and serum malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione peroxidase (GPX) activity, nitric oxide (NO), high-sensitivity C-reactive protein (hs-CRP), fasting blood sugar (FBS), lipid profile, and erythrocyte sedimentation rate (ESR) were measured. Seventy patients completed the trial. Compared to baseline, NAC significantly reduced morning stiffness (P < 0.001), DAS-28 (P < 0.001), ESR (P = 0.004), MDA (P < 0.001), NO (P < 0.001), hs-CRP (P = 0.006), FBS (P < 0.001), and low-density lipoprotein cholesterol (LDL-C) (P = 0.023) and significantly increased GPx activity (P = 0.015) and high-density lipoprotein cholesterol (HDL-C) level (P = 0.001). After treatment, remarkable differences were only seen between the two groups in serum NO (P = 0.003), FBS (P = 0.010), and HDL-C (P < 0.001) adjusted for baseline measures. There were no significant changes in morning stiffness, DAS-28, ESR, hs-CRP, MDA, TAC, GPx activity, triglyceride, total cholesterol, and LDL-C levels compared to the placebo group. In conclusion, NAC did not improve RA disease activity, but reduced NO and FBS and increased HDL-C levels. It appears that NAC should not be consumed as a replacement for routine medications prescribed in RA therapy, but it can be used as an adjunctive therapy.

Effects of Troponoids on Mitochondrial Function and Cytotoxicity

The α-hydroxytropolones (αHTs) are troponoid inhibitors of hepatitis B virus (HBV) replication that can target HBV RNase H with submicromolar efficacies. αHTs and related troponoids (tropones and tropolones) can be cytotoxic in cell lines as measured by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays that assess mitochondrial function. Previous studies suggest that tropolones induce cytotoxicity through inhibition of mitochondrial respiration. Therefore, we screened 35 diverse troponoids for effects on mitochondrial function, mitochondrial/nuclear genome ratios, cytotoxicity, and reactive oxygen species (ROS) production. Troponoids as a class did not inhibit respiration or glycolysis, although the α-ketotropolone subclass interfered with these processes. The troponoids had no impact on the mitochondrial DNA/nuclear DNA ratio after 3 days of compound exposure. The patterns of troponoid-induced cytotoxicity among three hepatic cell lines were similar for all compounds, but three potent HBV RNase H inhibitors were not cytotoxic in primary human hepatocytes. Tropolones and αHTs increased ROS production in cells at cytotoxic concentrations but had no effect at lower concentrations that efficiently inhibit HBV replication. Troponoid-mediated cytotoxicity was significantly decreased upon the addition of the ROS scavenger N-acetylcysteine. These studies show that troponoids can increase ROS production at high concentrations within cell lines, leading to cytotoxicity, but are not cytotoxic in primary hepatocytes. Future development of αHTs as potential therapeutics against HBV may need to mitigate ROS production by altering compound design and/or by coadministering ROS antagonists to ameliorate increased ROS levels.

Effect of N-acetylcysteine on remission maintenance in patients with ulcerative colitis: A randomized, double-blind controlled clinical trial

BACKGROUND

The use of antioxidant agents is suggested as a complementary therapy in UC patients for the prevention of flares. Considering the potent antioxidant activity of N-acetylcysteine (NAC), in the present study we aimed to assess the effect of this supplement on remission maintenance in patients with ulcerative colitis (UC).

METHODS

In the present double-blind randomized controlled clinical trial, 168 volunteer UC patients who were on high dose corticosteroid and Mesalamine for flare-up management, were recruited. The patients received 800 mg NAC or placebo for 16 weeks. Simultaneously, the prednisolone dose was tapered. The patients were followed up six more weeks post-intervention. The primary efficacy of the treatment was remaining in remission. The secondary outcomes were the endoscopic relapse, serum level of hs-CRP, hemoglobin, and fecal calprotectin level.

RESULTS

During 22 weeks follow up, 25 patients experienced relapses, six of them were in the NAC group and 19 of them were in the placebo group. There was a significant difference between the NAC and placebo groups regarding the relapse-free period (P = 0.007). Compared with the NAC group, significantly more patients in the placebo group had an endoscopic relapse (p < 0.001). At the end of the intervention period (16 weeks) and 6 weeks post-intervention, the mean fecal calprotectin, serum erythrocyte sedimentation rate, and hs-CRP levels were significantly lower in the NAC group compared with the placebo group (p < 0.05).

CONCLUSION

The findings indicated that NAC had a significantly more positive effect on the maintenance of remission compared with placebo in UC patients that were in the steroid-tapering phase of therapy.

N-Acetylcysteine (NAC): Impacts on Human Health

N-acetylcysteine (NAC) is a medicine widely used to treat paracetamol overdose and as a mucolytic compound. It has a well-established safety profile, and its toxicity is uncommon and dependent on the route of administration and high dosages. Its remarkable antioxidant and anti-inflammatory capacity is the biochemical basis used to treat several diseases related to oxidative stress and inflammation. The primary role of NAC as an antioxidant stems from its ability to increase the intracellular concentration of glutathione (GSH), which is the most crucial biothiol responsible for cellular redox imbalance. As an anti-inflammatory compound, NAC can reduce levels of tumor necrosis factor-alpha (TNF-α) and interleukins (IL-6 and IL-1β) by suppressing the activity of nuclear factor kappa B (NF-κB). Despite NAC's relevant therapeutic potential, in several experimental studies, its effectiveness in clinical trials, addressing different pathological conditions, is still limited. Thus, the purpose of this chapter is to provide an overview of the medicinal effects and applications of NAC to human health based on current therapeutic evidence.

Metabolic activation and colitis pathogenesis is prevented by lymphotoxin β receptor expression in neutrophils

Inflammatory bowel disease is characterized by an exacerbated intestinal immune response, but the critical mechanisms regulating immune activation remain incompletely understood. We previously reported that the TNF-superfamily molecule TNFSF14 (LIGHT) is required for preventing severe disease in mouse models of colitis. In addition, deletion of lymphotoxin beta receptor (LTβR), which binds LIGHT, also led to aggravated colitis pathogenesis. Here, we aimed to determine the cell type(s) requiring LTβR and the mechanism critical for exacerbation of colitis. Specific deletion of LTβR in neutrophils (LTβRΔN), but not in several other cell types, was sufficient to induce aggravated colitis and colonic neutrophil accumulation. Mechanistically, RNA-Seq analysis revealed LIGHT-induced suppression of cellular metabolism, and mitochondrial function, that was dependent on LTβR. Functional studies confirmed increased mitochondrial mass and activity, associated with excessive mitochondrial ROS production and elevated glycolysis at steady-state and during colitis. Targeting these metabolic changes rescued exacerbated disease severity. Our results demonstrate that LIGHT signals to LTβR on neutrophils to suppress metabolic activation and thereby prevents exacerbated immune pathogenesis during colitis.

An insight on safety, efficacy, and molecular docking study reports of N-acetylcysteine and its compound formulations

N-acetylcysteine (NAC) is considered as the body's major antioxidant molecules with diverse biological properties. In this review, the pharmacokinetics, safety and efficacy report on both the preclinical and clinical summary of NAC is discussed. Both in vitro and in vivo preclinical studies along with the clinical data have shown that NAC has enormous biological properties. NAC is used in the treatment of acetaminophen poisoning, diabetic nephropathy, Alzheimer's disease, schizophrenia, and ulcerative colitis, etc. Numerous analytical techniques, for instance, UPLC, LC-MS, HPLC, RP-IPC are primarily employed for the estimation of NAC in different single and fixed-dose combinations. The molecular docking studies on NAC demonstrate the binding within Sudlow's site-I hydrogen bonds and formation of NAC and BSA complexes. Various hydrophobic and hydrophilic amino acids generally exist in making contact with NAC as NAC-BSA complexes. Docking studies of NAC with the active site of the urease exposed an O-coordinated bond through nickel 3002 and a hydrogen bond through His-138. NAC and its analogs also made the allosteric pockets that helped to describe almost all favorable pose for the chaperone in a complex through the protein. Thus, we intended to highlight the several health benefits of this antioxidant compound and applications in pharmaceutical product development.

Preventing Colitis-Associated Colon Cancer With Antioxidants: A Systematic Review

Inflammatory bowel disease (IBD) patients have an increased risk of developing colitis-associated colon cancer (CAC); however, the basis for inflammation-induced genetic damage requisite for neoplasia is unclear. Several studies have shown that IBD patients have signs of increased oxidative damage, which could be a result of genetic and environmental factors such as an excess in oxidant molecules released during chronic inflammation, mitochondrial dysfunction, a failure in antioxidant capacity, or oxidant promoting diets. It has been suggested that chronic oxidative environment in the intestine leads to the DNA lesions that precipitate colon carcinogenesis in IBD patients. Indeed, several preclinical and clinical studies show that different endogenous and exogenous antioxidant molecules are effective at reducing oxidation in the intestine. However, most clinical studies have focused on the short-term effects of antioxidants in IBD patients but not in CAC. This review article examines the role of oxidative DNA damage as a possible precipitating event in CAC in the context of chronic intestinal inflammation and the potential role of exogenous antioxidants to prevent these cancers.

The effects of N-Acetylcysteine on serum level of inflammatory biomarkers in adults. Findings from a systematic review and meta-analysis of randomized clinical trials

PURPOSE

Randomized Clinical Trials (RCTs) have provided varied and conflicting findings regarding the effect of N-acetylcysteine (NAC) on inflammatory biomarkers. This study was conducted to review existing literature to determine whether NAC supplementation can affect inflammatory biomarkers in adults.

METHODS

Bibliographic databases of Scopus, and PubMed were used for relevant papers published until October 2019. Results were reported as weighted mean differences (WMD) with 95% confidence intervals (CI) using multi-level models. Cochrane's Q and I-squared (I2) tests were used to determine heterogeneity among studies.

RESULTS

Twenty-four RCTs which include 1057 sample size were entered to analysis. NAC doses and intervention duration ranged from 400 to 2000 mg/d, and 1 to 80 weeks, respectively. Oral supplementation of NAC reduced serum level of C-reactive protein (CRP) [WMD: -0.61 mg/L, 95% CI: -1.18 to -0.03, P = 0.039, I2 = 79.6%], and interleukin-6 (IL-6) [WMD: -0.43 pg/mL, 95% CI: -0.69 to -0.17, P = 0.001, I2 = 89.3%]. However, the effect of oral NAC supplementation on other inflammatory biomarkers was nonsignificant. Dose-response investigation showed a non-linear association between oral NAC supplementation with CRP.

CONCLUSION

Oral NAC supplementation reduced serum level of CRP and IL-6, but did not affect other inflammatory biomarkers. Nevertheless, more RCTs seems to be required to explore how NAC in different dosage and different routes of administration can affect inflammatory biomarkers.

Oxidative Stress and Redox-Modulating Therapeutics in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is associated with the production of reactive species that target cysteine redox switches in proteins, thereby affecting gene regulation, DNA damage, ion transport, intermediary metabolism, and mitochondrial function. Precursors of reactive species are derived from organic and inorganic compounds and their cofactors, including amino acids, vitamins, oxygen, nitrite, and sulfate. Nutrition and the gut microbiome fuel this process to a significant extent. The production of reactive species in IBD is reflected by a reduction in systemic free thiols, the major components of the antioxidant machinery. Systemic free thiols are amenable to nutritional or therapeutic intervention. This opens up future avenues for therapeutic modulation of redox status in IBD.

Efficacy and clinical monitoring strategies for immune checkpoint inhibitors and targeted cytokine immunotherapy for locally advanced and metastatic colorectal cancer

Colorectal cancer (CRC) is the fourth most common cancer type and is the second leading cause of cancer deaths annually in the United States. Conventional treatment options include postoperative (adjuvant) and preoperative (neoadjuvant) chemotherapy and radiotherapy. Although these treatment modalities have shown to decrease tumor burden, a major limitation to chemothearpy/radiotherapy is the high recurrence rate in patients. Immune-modulation strategies have emerged as a promising new therapeutic avenue to reduce this recurrence rate while minimizing undesirable systemic side effects. This review will focus specifically on the mechanisms of monoclonal antibodies: immune checkpoint inhibitors and cytokines, as well as current drugs approved by the Food and Drug Administration (FDA) and new clinical/pre-clinical trials. Finally, this review will investigate emerging methods used to monitor tumor response post-treatment.

Hydrogen peroxide production by lactobacilli promotes epithelial restitution during colitis

Inflammatory bowel disease (IBD) is a multifactorial chronic inflammatory disease of the gastrointestinal tract, characterized by cycles of acute flares, recovery and remission phases. Treatments for accelerating tissue restitution and prolonging remission are scarce, but altering the microbiota composition to promote intestinal homeostasis is considered a safe, economic and promising approach. Although probiotic bacteria have not yet fulfilled fully their promise in clinical trials, understanding the mechanism of how they exert beneficial effects will permit devising improved therapeutic strategies. Here we probe if one of the defining features of lactobacilli, the ability to generate nanomolar H2O2, contributes to their beneficial role in colitis. H2O2 generation by wild type L. johnsonii was modified by either deleting or overexpressing the enzymatic H2O2 source(s) followed by orally administering the bacteria before and during DSS colitis. Boosting luminal H2O2 concentrations within a physiological range accelerated recovery from colitis, while significantly exceeding this H2O2 level triggered bacteraemia. This study supports a role for increasing H2O2 within the physiological range at the epithelial barrier, independently of the enzymatic source and/or delivery mechanism, for inducing recovery and remission in IBD.

Pathomechanisms of Oxidative Stress in Inflammatory Bowel Disease and Potential Antioxidant Therapies

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease whose incidence has risen worldwide in recent years. Accumulating evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of IBD. This review highlights the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms in the gastrointestinal (GI) tract, the involvement of oxidative stress signaling in the initiation and progression of IBD and its relationships with genetic susceptibility and the mucosal immune response. In addition, potential therapeutic strategies for IBD that target oxidative stress signaling are reviewed and discussed. Though substantial progress has been made in understanding the role of oxidative stress in IBD in humans and experimental animals, the underlying mechanisms are still not well defined. Thus, further studies are needed to validate how oxidative stress signaling is involved in and contributes to the development of IBD.

ROS in gastrointestinal inflammation: Rescue Or Sabotage?

The intestine is composed of many distinct cell types that respond to commensal microbiota or pathogens with immune tolerance and proinflammatory signals respectively. ROS produced by mucosa-resident cells or by newly recruited innate immune cells are essential for antimicrobial responses and regulation of signalling pathways including processes involved in wound healing. Impaired ROS production due to inactivating patient variants in genes encoding NADPH oxidases as ROS source has been associated with Crohn's disease and pancolitis, whereas overproduction of ROS due to up-regulation of oxidases or altered mitochondrial function was linked to ileitis and ulcerative colitis. Here, we discuss recent advances in our understanding of how maintaining a redox balance is crucial to preserve gut homeostasis.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Roles of Dietary Amino Acids and Their Metabolites in Pathogenesis of Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) is a kind of chronic inflammation, which has increasing incidence and prevalence in recent years. IBD mainly divides into Crohn's disease (CD) and ulcerative colitis (UC). It is hard to cure IBD completely, and novel therapies are urgently needed. Amino acids (AAs) and their metabolites are regarded as important nutrients for humans and animals and also play an important role in IBD amelioration. In the present study, the potential protective effects of AAs and their metabolites on IBD had been summarized with the objective to provide insights into IBD moderating using dietary AAs and their metabolites as a potential adjuvant therapy.

Antioxidant Supplements and Gastrointestinal Diseases: A Critical Appraisal

The gastrointestinal tract digests and absorbs dietary nutrients, protects the body against physical and chemical damage from contents in its lumen, provides immunity against external antigens, and keeps an optimum environment for the gut microbiota. These functions cannot be performed normally in several diseases of which the following are discussed here: irritable bowel syndrome and inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis. Because these diseases are associated with oxidative stress, a host of antioxidant supplements are used for maintenance and recovery of the gut functions. However, the benefits of these supplements have not been established. The available 80 human trials were rated for levels of confidence and for benefits of the antioxidant supplements. For Crohn's disease, the supplements for which clear benefits occurred in at least 2 studies were allopurinol, Boswellia serrata (frankincense or shallaki), Artemesia species (wormwood), Tripterygium wilfordii (léi gōng téng), and omega-3 fatty acids. Similar beneficial supplements for ulcerative colitis were allopurinol, Matricaria chamomilla (chamomile), Curcuma longa (curcumin in turmeric), and omega-3 fatty acids. There was also a clear benefit for ulcerative colitis in 2 studies where a multiherbal Chinese medicine preparation and an Ayurvedic medicine preparation were used. For irritable bowel syndrome, there was only a marginal benefit of some of the antioxidant supplements. Thus, some antioxidant supplements may be beneficial at certain stages of specific diseases. This is consistent with the current concept that antioxidants act by inhibiting oxidative stress pathways in a tissue- and environment-specific manner and not by simply acting as scavengers.

Colonic and Hepatic Modulation by Lipoic Acid and/or N-Acetylcysteine Supplementation in Mild Ulcerative Colitis Induced by Dextran Sodium Sulfate in Rats

Lipoic acid (LA) and N-acetylcysteine (NAC) are antioxidant and anti-inflammatory agents that have not yet been tested on mild ulcerative colitis (UC). This study aims to evaluate the action of LA and/or NAC, on oxidative stress and inflammation markers in colonic and hepatic rat tissues with mild UC, induced by dextran sodium sulfate (DSS) (2% w/v). LA and/or NAC (100 mg·kg·day^-1, each) were given, once a day, in the diet, in a pretreatment phase (7 days) and during UC induction (5 days). Colitis induction was confirmed by histological and biochemical analyses (high performance liquid chromatography, spectrophotometry, and Multiplex®). A redox imbalance occurred before an immunological disruption in the colon. NAC led to a decrease in hydrogen peroxide (H₂O₂), malondialdehyde (MDA) levels, and myeloperoxidase activity. In the liver, DSS did not cause damage but treatments with both antioxidants were potentially harmful, with LA increasing MDA and LA + NAC increasing H₂O₂, tumor necrosis factor alpha, interferon gamma, and transaminases. In summary, NAC exhibited the highest colonic antioxidant and anti-inflammatory activity, while LA + NAC caused hepatic damage.

Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine

Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.

Antioxidant therapy for treatment of inflammatory bowel disease: Does it work?

Oxidative stress (OS) is considered as one of the etiologic factors involved in several signals and symptoms of inflammatory bowel diseases (IBD) that include diarrhea, toxic megacolon and abdominal pain. This systematic review discusses approaches, challenges and perspectives into the use of nontraditional antioxidant therapy on IBD, including natural and synthetic compounds in both human and animal models. One hundred and thirty four papers were identified, of which only four were evaluated in humans. Some of the challenges identified in this review can shed light on this fact: lack of standardization of OS biomarkers, absence of safety data and clinical trials for the chemicals and biological molecules, as well as the fact that most of the compounds were not repeatedly tested in several situations, including acute and chronic colitis. This review hopes to stimulate researchers to become more involved in this fruitful area, to warrant investigation of novel, alternative and efficacious antioxidant-based therapies.

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Major biomarkers used for evaluation of antioxidant therapy were MPO, TBARS/MDA and glutathione levels.

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Challenges were identified for the yet poor use of antioxidant therapy in IBD.

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This review stimulates the investigation of alternative and efficacious antioxidant therapies.

Review article: the role of oxidative stress in pathogenesis and treatment of inflammatory bowel diseases

In this review, we focus on the role of oxidative stress in the aetiology of inflammatory bowel diseases (IBD) and colitis-associated colorectal cancer and discuss free radicals and free radical-stimulated pathways as pharmacological targets for anti-IBD drugs. We also suggest novel anti-oxidative agents, which may become effective and less-toxic alternatives in IBD and colitis-associated colorectal cancer treatment. A Medline search was performed to identify relevant bibliography using search terms including: ‘free radicals,’ ‘antioxidants,’ ‘oxidative stress,’ ‘colon cancer,’ ‘ulcerative colitis,’ ‘Crohn’s disease,’ ‘inflammatory bowel disease.’ Several therapeutics commonly used in IBD treatment, among which are immunosuppressants, corticosteroids and anti-TNF-α antibodies, could also affect the IBD progression by interfering with cellular oxidative stress and cytokine production. Experimental data shows that these drugs may effectively scavenge free radicals, increase anti-oxidative capacity of cells, influence multiple signalling pathways, e.g. MAPK and NF-kB, and inhibit pro-oxidative enzyme and cytokine concentration. However, their anti-oxidative and anti-inflammatory effectiveness still needs further investigation. A highly specific antioxidative activity may be important for the clinical treatment and relapse of IBD. In the future, a combination of currently used pharmaceutics, together with natural and synthetic anti-oxidative compounds, like lipoic acid or curcumine, could be taken into account in the design of novel anti-IBD therapies.

An anti-inflammatory diet as treatment for inflammatory bowel disease: a case series report

Background

The Anti-Inflammatory Diet (IBD-AID) is a nutritional regimen for inflammatory bowel disease (IBD) that restricts the intake of certain carbohydrates, includes the ingestion of pre- and probiotic foods, and modifies dietary fatty acids to demonstrate the potential of an adjunct dietary therapy for the treatment of IBD.

Methods

Forty patients with IBD were consecutively offered the IBD-AID to help treat their disease, and were retrospectively reviewed. Medical records of 11 of those patients underwent further review to determine changes in the Harvey Bradshaw Index (HBI) or Modified Truelove and Witts Severity Index (MTLWSI), before and after the diet.

Results

Of the 40 patients with IBD, 13 patients chose not to attempt the diet (33%). Twenty-four patients had either a good or very good response after reaching compliance (60%), and 3 patients’ results were mixed (7%). Of those 11 adult patients who underwent further medical record review, 8 with CD, and 3 with UC, the age range was 19–70 years, and they followed the diet for 4 or more weeks. After following the IBD-AID, all (100%) patients were able to discontinue at least one of their prior IBD medications, and all patients had symptom reduction including bowel frequency. The mean baseline HBI was 11 (range 1–20), and the mean follow-up score was 1.5 (range 0–3). The mean baseline MTLWSI was 7 (range 6–8), and the mean follow-up score was 0. The average decrease in the HBI was 9.5 and the average decrease in the MTLWSI was 7.

Conclusion

This case series indicates potential for the IBD-AID as an adjunct dietary therapy for the treatment of IBD. A randomized clinical trial is warranted.

Oral 5-aminosalicylic acid for induction of remission in ulcerative colitis

BACKGROUND

Oral 5-aminosalicylic acid (5-ASA) preparations were intended to avoid the adverse effects of sulfasalazine (SASP) while maintaining its therapeutic benefits. Previously, it was found that 5-ASA drugs in doses of at least 2 g/day, were more effective than placebo but no more effective than SASP for inducing remission in ulcerative colitis. This updated review includes more recent studies and evaluates the efficacy and safety of 5-ASA preparations used for the treatment of mild to moderately active ulcerative colitis.

OBJECTIVES

The primary objectives were to assess the efficacy, dose-responsiveness and safety of oral 5-ASA compared to placebo, SASP, or 5-ASA comparators for induction of remission in active ulcerative colitis. A secondary objective of this systematic review was to compare the efficacy and safety of once daily dosing of oral 5-ASA with conventional (two or three times daily) dosing regimens.

SEARCH METHODS

A computer-assisted literature search for relevant studies (inception to January 20, 2012) was performed using MEDLINE, EMBASE and the Cochrane Library. Review articles and conference proceedings were also searched to identify additional studies.

SELECTION CRITERIA

Studies were accepted for analysis if they were randomized controlled clinical trials of parallel design, with a minimum treatment duration of four weeks. Studies of oral 5-ASA therapy for treatment of patients with active ulcerative colitis compared with placebo, SASP or other formulations of 5-ASA were considered for inclusion. Studies that compared once daily 5-ASA treatment with conventional dosing of 5-ASA (two or three times daily) and 5-ASA dose ranging studies were also considered for inclusion.

DATA COLLECTION AND ANALYSIS

The outcomes of interest were the failure to induce global/clinical remission, global/clinical improvement, endoscopic remission, endoscopic improvement, adherence, adverse events, withdrawals due to adverse events, and withdrawals or exclusions after entry. Trials were separated into five comparison groups: 5-ASA versus placebo, 5-ASA versus sulfasalazine, once daily dosing versus conventional dosing, 5-ASA versus comparator 5-ASA, and 5-ASA dose-ranging. Placebo-controlled trials were subgrouped by dosage. SASP-controlled trials were subgrouped by 5-ASA/SASP mass ratios. Once daily versus conventional dosing studies were subgrouped by formulation. 5-ASA-controlled trials were subgrouped by common 5-ASA comparators (e.g. Asacol, Claversal, Salofalk and Pentasa). Dose-ranging studies were subgrouped by 5-ASA formulation. We calculated the relative risk (RR) and 95% confidence intervals (95% CI) for each outcome. Data were analyzed on an intention to treat basis.

MAIN RESULTS

Forty-eight studies (7776 patients) were included. The majority of included studies were rated as low risk of bias. 5-ASA was significantly superior to placebo with regard to all measured outcome variables. Seventy-two per cent of 5-ASA patients failed to enter clinical remission compared to 85% of placebo patients (RR 0.86, 95% CI 0.81 to 0.91). A dose-response trend for 5-ASA was also observed. No statistically significant differences in efficacy were found between 5-ASA and SASP. Fifty-four per cent of 5-ASA patients failed to enter remission compared to 58% of SASP patients (RR 0.90, 95% CI 0.77 to 1.04). No statistically significant differences in efficacy or adherence were found between once daily and conventionally dosed 5-ASA. Forty-two per cent of once daily patients failed to enter clinical remission compared to 44% of conventionally dosed patients (RR 0.95, 95% CI 0.82 to 1.10). Eight per cent of patients dosed once daily failed to adhere to their medication regimen compared to 6% of conventionally dosed patients (RR 1.36, 95% CI 0.64 to 2.86). There does not appear to be any difference in efficacy among the various 5-ASA formulations. Forty-eight per cent of patients in the 5-ASA group failed to enter remission compared to 50% of patients in the 5-ASA comparator group (RR 0.94, 95% CI 0.86 to 1.03). A pooled analysis of the ASCEND (I, II and III, n = 1459 patients) studies found no statistically significant difference in clinical improvement between Asacol 4.8 g/day and 2.4 g/day used for the treatment of moderately active ulcerative colitis. Thirty-seven per cent of patients in the 4.8 g/day group failed to improve clinically compared to 41% of patients in the 2.4 g/day group (RR 0.89; 95% CI 0.78 to 1.01). Subgroup analysis indicated that patients with moderate disease may benefit from the higher dose of 4.8 g/day. One study compared (n = 123 patients) Pentasa 4 g/day to 2.25 g/day in patients with moderate disease. Twenty-five per cent of patients in the 4 g/day group failed to improve clinically compared to 57% of patients in the 2.25 g/day group (RR 0.44; 95% CI 0.27 to 0.71). A pooled analysis of two studies comparing MMX mesalamine 4.8 g/day to 2.4 g/day found no statistically significant difference in efficacy (RR 1.03, 95% CI 0.82 to 1.29). 5-ASA was generally safe and common adverse events included flatulence, abdominal pain, nausea, diarrhea, headache and worsening ulcerative colitis. There were no statistically significant differences in the incidence of adverse events between 5-ASA and placebo, once daily and conventionally dosed 5-ASA, 5-ASA and comparator 5-ASA formulation and 5-ASA dose ranging (high dose versus low dose) studies. SASP was not as well tolerated as 5-ASA. Twenty-nine percent of SASP patients experienced an adverse event compared to 15% of 5-ASA patients (RR 0.48, 95% CI 0.37 to 0.63).

AUTHORS' CONCLUSIONS

5-ASA was superior to placebo and no more effective than SASP. Considering their relative costs, a clinical advantage to using oral 5-ASA in place of SASP appears unlikely. 5-ASA dosed once daily appears to be as efficacious and safe as conventionally dosed 5-ASA. Adherence does not appear to be enhanced by once daily dosing in the clinical trial setting. It is unknown if once daily dosing of 5-ASA improves adherence in a community-based setting. There do not appear to be any differences in efficacy or safety among the various 5-ASA formulations. A daily dosage of 2.4 g appears to be a safe and effective induction therapy for patients with mild to moderately active ulcerative colitis. Patients with moderate disease may benefit from an initial dose of 4.8 g/day.

Oxidative stress and redox signaling mechanisms of inflammatory bowel disease: updated experimental and clinical evidence

Inflammatory bowel disease (IBD) comprises primarily the chronic relapsing inflammatory disorders, Crohn's disease and ulcerative colitis, with the former affecting any part of the gastrointestinal tract and the latter mainly afflicting the colon. The precise etiology of IBD remains unclear, and it is thought that interactions among various factors, including genetic factors, the host immune system and environmental factors, cause disruption of intestinal homeostasis, leading to dysregulated inflammatory responses of the gut. As inflammation is intimately related to formation of reactive intermediates, including reactive oxygen and nitrogen species (ROS/RNS), oxidative stress has been proposed as a mechanism underlying the pathophysiology of IBD. This review is intended to summarize succinctly recent new experimental and clinical evidence supporting oxidative stress as a pathophysiological component of IBD and point to the potential of using antioxidant compounds as promising therapeutic modalities of human IBD. The sources of ROS/RNS and the redox signaling mechanism underlying oxidative stress and inflammation in IBD are discussed to provide insight into the molecular basis of oxidative stress as a pathophysiological factor in IBD.

5-aminosalicylic acid (5-ASA) can reduce levels of oxidative DNA damage in cells of colonic mucosa with and without fecal stream

BACKGROUND

No studies have evaluated the effectiveness of 5-ASA against oxidative DNA damage in experimental models of diversion colitis.

AIM

To evaluate the effects of 5-ASA against oxidative DNA damage in an experimental model of diversion colitis.

METHODS

Twenty-six Wistar rats were divided into two groups corresponding to sacrifice at 2 or 4 weeks after fecal diversion of the left colon by means of proximal colostomy and distal mucosa fistula. Each group was divided into two subgroups according to intervention in excluded colon performed with 0.9% saline solution or 5-ASA. Level of oxidative DNA damage was determined by comet assay in cells obtained from segments with and without fecal stream before and after H2O2 challenge. For statistical analysis, was used one-way analysis of variance (ANOVA), adopting a 5% significance level (P<0.05).

RESULTS

Levels of DNA damage were always higher in colon segments without fecal stream, regardless of the intervention solution employed. DNA damage in colon segments with and without fecal stream in animals irrigated with 5-ASA was lower when compared with those treated with saline solution, regardless of time of irrigation. These levels remained lower after intervention with 5-ASA, even after H2O2 challenge.

CONCLUSIONS

Enema with 5-ASA reduces oxidative DNA damage in epithelial cells of colon segments without fecal stream, even after H2O2 challenge, confirming the effects of 5-ASA against DNA damage by oxygen free radicals.

Blockade of a chemokine, CCL2, reduces chronic colitis-associated carcinogenesis in mice

Accumulating evidence indicates the crucial contribution of chronic inflammation to various types of carcinogenesis, including colon carcinoma associated with ulcerative colitis and asbestosis-induced malignant mesothelioma. Ulcerative colitis-associated colon carcinogenesis can be recapitulated in mice by azoxymethane administration followed by repetitive dextran sulfate sodium ingestion. In the course of this carcinogenesis process, the expression of a macrophage-tropic chemokine, CCL2, was enhanced together with intracolonic massive infiltration of macrophages, which were a major source of cyclooxygenase (COX)-2, a crucial mediator of colon carcinogenesis. Mice deficient in CCL2-specific receptor, CCR2, exhibited less macrophage infiltration and lower tumor numbers with attenuated COX-2 expression. Moreover, CCL2 antagonists decreased intracolonic macrophage infiltration and COX-2 expression, attenuated neovascularization, and eventually reduced the numbers and size of colon tumors, even when given after multiple colon tumors have developed. These observations identify CCL2 as a crucial mediator of the initiation and progression of chronic colitis-associated colon carcinogenesis and suggest that targeting CCL2 may be useful in treating colon cancers, particularly those associated with chronic inflammation.