Indomethacin-induced mitochondrial dysfunction and oxidative stress in villus enterocytes

Wheat peptides inhibit the activation of MAPK and NF-κB inflammatory pathways and maintain epithelial barrier integrity in NSAID-induced intestinal epithelial injury

The use of non-steroidal anti-inflammatory drugs (NSAIDs) has negative effects on the gastrointestinal tract, but the proton pump inhibitors currently in use only protect against gastrointestinal disease and may even make NSAID-induced enteropathy worse. Therefore, new approaches to treating enteropathy are required. This study aimed to investigate the protective effect of wheat peptides (WPs) against NSAID-induced intestinal damage in mice and their mechanism. Here, an in vivo mouse model was built to investigate the protective and reparative effects of different concentrations of WPs on NSAID-induced intestinal injury. WPs ameliorated NSAID-induced weight loss and small intestinal tissue damage in mice. WP treatment inhibited NSAID-induced injury leading to increased levels of oxidative stress and expression levels of inflammatory factors. WPs protected and repaired the integrity and permeability injury of the intestinal tight junction induced by NSAIDs. An in vitro Caco-2 cell model was built with lipopolysaccharide (LPS). WP pretreatment inhibited LPS-induced changes in the Caco-2 cell permeability and elevated the levels of oxidative stress. WPs inhibited LPS-induced phosphorylation of NF-κB p65 and mitogen-activated protein kinase (MAPK) signaling pathways and reduced the expression of inflammatory factors. In addition, WPs increased tight junction protein expression, which contributed to improved intestinal epithelial dysfunction. Our results suggest that WPs can ameliorate NSAID-induced impairment of intestinal barrier functional integrity by improving intestinal oxidative stress levels and reducing inflammatory factor expression through inhibition of NF-κB p65 and MAPK signaling pathway activation. WPs can therefore be used as potential dietary supplements to reduce NSAID-induced injury of the intestine.

Nonsteroidal anti-inflammatory drugs sensitize epithelial cells to Clostridioides difficile toxin-mediated mitochondrial damage

Clostridioides difficile damages the colonic mucosa through the action of two potent exotoxins. Factors shaping C. difficile pathogenesis are incompletely understood but are likely due to the ecological factors in the gastrointestinal ecosystem, mucosal immune responses, and environmental factors. Little is known about the role of pharmaceutical drugs during C. difficile infection (CDI), but recent studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) worsen CDI. The mechanism underlying this phenomenon remains unclear. Here, we show that NSAIDs exacerbate CDI by disrupting colonic epithelial cells (CECs) and sensitizing cells to C. difficile toxin-mediated damage independent of their canonical role of inhibiting cyclooxygenase (COX) enzymes. Notably, we find that NSAIDs and C. difficile toxins target the mitochondria of CECs and enhance C. difficile toxin-mediated damage. Our results demonstrate that NSAIDs exacerbate CDI by synergizing with C. difficile toxins to damage host cell mitochondria. Together, this work highlights a role for NSAIDs in exacerbating microbial infection in the colon.

Pain killers: the interplay between nonsteroidal anti-inflammatory drugs and Clostridioides difficile infection

Clostridioides difficile is one of the leading causes of nosocomial infections worldwide. Increases in incidence, severity, and healthcare cost associated with C. difficile infection (CDI) have made this pathogen an urgent public health threat worldwide. The factors shaping the evolving epidemiology of CDI and impacting clinical outcomes of infection are not well understood, but involve tripartite interactions between the host, microbiota, and C. difficile. In addition to this, emerging data suggests an underappreciated role for environmental factors, such as diet and pharmaceutical drugs, in CDI. In this review, we discuss the role of nonsteroidal anti-inflammatory drugs (NSAIDs) and eicosanoids in CDI.

Reprogramming of H3K9bhb at regulatory elements is a key feature of fasting in the small intestine

β-hydroxybutyrate (β-OHB) is an essential metabolic energy source during fasting and functions as a chromatin regulator by lysine β-hydroxybutyrylation (Kbhb) modification of the core histones H3 and H4. We report that Kbhb on histone H3 (H3K9bhb) is enriched at proximal promoters of critical gene subsets associated with lipolytic and ketogenic metabolic pathways in small intestine (SI) crypts during fasting. Similar Kbhb enrichment is observed in Lgr5⁺ stem cell-enriched epithelial spheroids treated with β-OHB in vitro. Combinatorial chromatin state analysis reveals that H3K9bhb is associated with active chromatin states and that fasting enriches for an H3K9bhb-H3K27ac signature at active metabolic gene promoters and distal enhancer elements. Intestinal knockout of Hmgcs2 results in marked loss of H3K9bhb-associated loci, suggesting that local production of β-OHB is responsible for chromatin reprogramming within the SI crypt. We conclude that modulation of H3K9bhb in SI crypts is a key gene regulatory event in response to fasting.

Terranova et al. demonstrate that fasting induces production of HMGCS2 and β-hydroxybutyrate in small intestine (SI) crypt cells. This causes enrichment of H3K9bhb within regulatory regions of critical metabolic genes in crypt epithelial cells. Loss of intestinal Hmgcs2 impairs H3K9bhb enrichment and affects expression of H3K9bhb-associated metabolic gene programs.

Gastroprotective Effects of Spirulina platensis, Golden Kiwifruit Flesh, and Golden Kiwifruit Peel Extracts Individually or in Combination against Indomethacin-Induced Gastric Ulcer in Rats

This study was conducted to investigate the therapeutic effect of hydro-alcoholic extract of Spirulina platensis (SP), golden kiwifruit (Actinidia chinensis) flesh (KF), and golden kiwifruit peel (KP) individually or in combination (SFP) on indomethacin-induced gastric ulcer in rats. Negative control rats (GI) were orally administered distilled water in parallel with other treatments. The positive control rat group (GII) was administered 30 mg kg⁻¹ indomethacin to induce gastric ulcers. The KF and KF extracts were used individually or together with SP in treating indomethacin-induced gastric ulcerated rat groups. Gastric ulcerated rat’s groups GIII, GIV, GV, GVI, and GVII were orally administered at 30 mg kg⁻¹ rat body weight as total phenolic content (TPC) equivalent from SP, KF, KP, SPF extracts, and Lansoprazole (30 mg kg⁻¹, as reference drug) daily up to 14 days, respectively. The relevant biochemical parameters, antioxidant biomarkers, and histopathological examination were examined. Remarkably, treating rats with SP, KF, KP, and SFP extracts markedly reduced gastric juice and stomach volume expansion induced by indomethacin. The SP significantly retrieved the pH of gastric juice to a regular rate compared to GI. The ulcer index (UI) was significantly attenuated by SP, KF, KP, and SFP administration. The protection index percentage (PI %) was 80.79, 54.51, 66.08, 75.74, and 74.86% in GIII, GIV, GV, GVI, and GVII, respectively. The gastric mucin content was significantly better attenuated by 95.7 in GIII compared to its content in GI. Lansoprazole increased mucin content by 80.3%, which was considerably lower than SP and SFP. SP, KF, KP, SFP, and Lansoprazole improved the reform of gastric mucosal-increased secreted mucus by 95.6, 61.3, 64.8, 103.1, and 80.2% in GIII, GIV, GV, GVI, and GVII, respectively. Interestingly, SFP efficiently increased vit. B₁₂ level by 46.0% compared to other treatments. While Lansoprazole administrating did not significantly attenuate vit. B₁₂ level. The SP and SFP improved iron and Hemoglobin (HB) levels depending on treatment. SP, KF, KP, and SFP significantly decreased the malondialdehyde (MDA) and increased reduced glutathione (GSH) as well as superoxide dismutase (SOD) levels in blood and stomach tissues. The most potent effect was observed with SP, and SFP was even better than Lansoprazole. Histopathologically, treating rats with SP extract showed a marked reduction of gastric damage and severity changes induced by indomethacin. KP was much better than KF in lessening gastric histopathological damages caused by indomethacin. SFP significantly alleviates gastric histopathological alterations. The lansoprazole-treated group (GVII) greatly relieved the gastric histopathological changes and recorded mild focal necrosis and desquamation of the mucosa in addition to mild oedema in the serosal layer. In conclusion, the presented results proved the antiulcer potential of SP and A. chinensis extracts against an indomethacin-induced gastric ulcer in rats, which may be due to their antioxidant and anti-inflammation efficiency. Thus, these data suggested that SP, KF, KP, and SFP extracts as natural and safe alternatives have a gastroprotective potential against indomethacin-induced gastric ulceration. The antioxidative and anti-inflammatory properties are probable mechanisms.

Plasma membrane integrity: implications for health and disease

Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.

A reactive oxygen species-responsive antioxidant nanotherapy for the treatment of drug-induced tissue and organ injury

Drug-induced tissue injury has become a growing public health problem. Gastrointestinal injury and liver dysfunction are the most common side effects related to drug therapies, resulting in high morbidity and mortality in recent years. The overproduction of reactive oxygen species (ROS) is critically involved in the pathogenesis of drug-induced tissue injury. Consequently, antioxidant therapy represents a very promising strategy for the treatment of drug-induced tissue injury. Herein, a multifunctional antioxidant nanotherapy (TON) is engineered from a cyclodextrin-derived ROS-responsive material and a radical scavenger tempol, and is capable of eliminating a broad spectrum of ROS. After oral administration, TON can passively accumulate in the inflamed gastrointestinal tissues in mice with indomethacin-induced gastrointestinal injury. Correspondingly, TON shows superior efficacy in two representative murine models of indomethacin-induced gastrointestinal injury and acetaminophen-induced hepatic injury via attenuating oxidative stress and mitigating inflammatory responses. Additionally, preliminary in vitro and in vivo experiments demonstrate the good safety profile of TON. Consequently, the ROS-responsive antioxidant nanotherapy TON is promising for the treatment of drug-induced tissue and organ injury.

Glycomacropeptide Ameliorates Indomethacin-Induced Enteropathy in Rats by Modifying Intestinal Inflammation and Oxidative Stress

Nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy is considered a serious and increasing clinical problem without available treatment. Glycomacropeptide (GMP) is a 64-amino acid peptide derived from milk κ-casein with numerous biological activities. The aim of this study was to investigate the protective effect of GMP on NSAID enteropathy in rats. Enteropathy was induced by seven days oral indomethacin administration. Rats were orally GMP treated from seven days previous and during the establishment of the enteropathy model. Changes in metabolism, hematological and biochemical blood alterations, intestinal inflammation and oxidative damage were analyzed. Integrity barrier markers, macroscopic intestinal damage and survival rate were also evaluated. GMP treatment prevented anorexia and weight loss in animals. Furthermore, prophylaxis with GMP ameliorated the decline in hemoglobin, hematocrit, albumin and total protein levels. The treatment had no therapeutic efficacy on the decrease of occludin and mucin (MUC)-2 expression in intestinal tissue. However, GMP markedly decreased neutrophil infiltration, and CXCL1, interleukin-1β and inducible nitric oxide synthase expression. Nitric oxide production and lipid hydroperoxide level in the small intestine were also diminished. These beneficial effects were mirrored by preventing ulcer development and increasing animal survival. These results suggest that GMP may protect against NSAID enteropathy through anti-inflammatory and antioxidant properties.

Study of Melatonin as Preventive Agent of Gastrointestinal Damage Induced by Sodium Diclofenac

Safety profile of nonsteroidal anti-inflammatory drugs (NSAIDs) has been widely studied and both therapeutic and side effects at the gastric and cardiovascular level have been generally associated with the inhibitory effect of isoform 1 (COX-1) and 2 (COX-2) cyclooxygenase enzymes. Now there are evidences of the involvement of multiple cellular pathways in the NSAIDs-mediated-gastrointestinal (GI) damage related to enterocyte redox state. In a previous review we summarized the key role of melatonin (MLT), as an antioxidant, in the inhibition of inflammation pathways mediated by oxidative stress in several diseases, which makes us wonder if MLT could minimize GI NSAIDs side effects. So, the aim of this work is to study the effect of MLT as preventive agent of GI injury caused by NSAIDs. With this objective sodium diclofenac (SD) was administered alone and together with MLT in two experimental models, ex vivo studies in pig intestine, using Franz cells, and in vivo studies in mice where stomach and intestine were studied. The histological evaluation of pig intestine samples showed that SD induced the villi alteration, which was prevented by MLT. In vivo experiments showed that SD altered the mice stomach mucosa and induced tissue damage that was prevented by MLT. The evaluation by quantitative reverse transcription PCR (RT-qPCR) of two biochemical markers, COX-2 and iNOS, showed an increase of both molecules in less injured tissues, suggesting that MLT promotes tissue healing by improving redox state and by increasing iNOS/NO that under non-oxidative condition is responsible for the maintenance of GI-epithelium integrity, increasing blood flow and promoting angiogenesis and that in presence of MLT, COX-2 may be responsible for wound healing in enterocyte. Therefore, we found that MLT may be a preventive agent of GI damages induced by NSAIDs.

Comparative effect of indomethacin (IndoM) on the enzymes of carbohydrate metabolism, brush border membrane and oxidative stress in the kidney, small intestine and liver of rats

Indomethacin (IndoM) has prominent anti-inflammatory and analgesic-antipyretic properties. However, high incidence and severity of side-effects on the structure and functions of the kidney, liver and intestine limits its clinical use. The present study tested the hypothesis that IndoM causes multi-organ toxicity by inducing oxidative stress that alters the structure of various cellular membranes, metabolism and hence functions. The effect of IndoM was determined on the enzymes of carbohydrate metabolism, brush border membrane (BBM) and oxidative stress in the rat kideny, liver and intestine to understand the mechanism of IndoM induced toxicity. Adult male Wister rats were given IndoM (20 mg/kg) intra-peritoneally in sodium bicarbonate twice a day for 3 d. The body weights of the rats were recorded before and after experimental procedure. IndoM administration significantly increased blood urea nitrogen, serum creatinine, cholesterol and alkaline phosphatase but inorganic phosphate indicating IndoM induced renal, hepatic and intestinal toxicity. Activity of lactate dehydrogenase along with glucose-6- and fructose-1, 6-bis phosphatase, glucose-6-phosphate dehydrogenase and NADP-malic enzyme increased but malate dehydrogenase decreased in all tissues. Lipid peroxidation (LPO) significantly increased whereas the antioxidant enzymes decreased in all rat tissues studied. The results indicate that IndoM administration caused severe damage to kidney, liver and intestine by icreasing LPO, suppressing antioxidant enzymes and inhibiting oxidative metablolism. The energy dependence was shifted to anaerobic glycolysis due to mitochondrial damage supported by increased gluconeogenesis to provide more glucose to meet energy requirements.

Repeated administration of the NSAID meloxicam alters the plasma and urine lipidome

Non-steroidal anti-inflammatories (NSAIDs), such as meloxicam, are the mainstay for treating painful and inflammatory conditions in animals and humans; however, the repeated administration of NSAIDs can cause adverse effects, limiting the long-term administration of these drugs to some patients. The primary aim of this study was to determine the effects of repeated meloxicam administration on the feline plasma and urine lipidome. Cats (n = 12) were treated subcutaneously with either saline solution or 0.3 mg/kg body weight of meloxicam daily for up to 31 days. Plasma and urine lipidome were determined by LC-MS before the first treatment and at 4, 9 and 13 and 17 days after the first administration of meloxicam. The repeated administration of meloxicam altered the feline plasma and urine lipidome as demonstrated by multivariate statistical analysis. The intensities of 94 out of 195 plasma lipids were altered by the repeated administration of meloxicam to cats (p < 0.05). Furthermore, we identified 12 lipids in plasma and 10 lipids in urine that could serve as biomarker candidates for discriminating animals receiving NSAIDs from healthy controls. Expanding our understanding about the effects of NSAIDs in the body could lead to the discovery of mechanism(s) associated with intolerance to NSAIDs.

In vitro screening of cell bioenergetics to assess mitochondrial dysfunction in drug development

Drug-induced mitochondrial toxicity is considered as a common cellular mechanism that can induce a variety of organ toxicities. In the present manuscript, 17 in vitro mitochondrial toxic drugs, reported to induce Drug-Induced Liver Injury (DILI) and 6 non-mitochondrial toxic drugs (3 with DILI and 3 without DILI concern), were tested in HepG2 cells using a bioenergetics system. The 17 mitochondrial toxic drugs represent a wide variety of mitochondrial dysfunctions as well as DILI and include 4 pairs of drugs which are structurally related but associated with different DILI concerns in human. Cell bioenergetics were measured using the XF96e analyzer which simultaneous monitor oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), indirect measurements of oxidative phosphorylation and glycolysis, respectively. OCR associated with ATP production, maximal respiration, proton leak and spare respiratory capacity, were also assessed. Duplicate experiments resulted in a sensitivity of 82% (14/17) and specificity of 83% (5/6). The addition of stressors improved specificity considerably. Cut-offs, statistics and rules are clearly discussed to facilitate the use of this assay for screening purposes. Overall, the authors consider that this assay should be part of the battery of safety screening assays at early stages of drug development.

The Relationship Between Nonsteroidal Anti-inflammatory Drug Use and Age-related Macular Degeneration

PURPOSE

To describe the relationship between the incidence of age-related macular degeneration (AMD) and nonsteroidal anti-inflammatory drug (NSAIDs) use.

DESIGN

Prospective cohort study.

METHODS

This study consisted of participants in the California Men's Health Study. Those who completed surveys in 2002-2003 and 2006 were included. Men who self-reported use of aspirin, ibuprofen, naproxen, valdecoxib, celecoxib, and/or rofecoxib at least 3 days per week were considered NSAID users. Patients were categorized as non-users, former users, new users, or longer-term users based on survey responses. NSAID use was also categorized by type: any NSAIDs, aspirin, and/or non-aspirin NSAIDs. Age, race/ethnicity, smoking status, education, income, alcohol use, and Charlson comorbidity index score were included in the multivariate analysis as risk factors for AMD.

RESULTS

A total of 51 371 men were included. Average follow-up time was 7.4 years. There were 292 (0.6%) and 1536 (3%) cases of exudative and nonexudative AMD, respectively. Longer-term use of any NSAID was associated with lower risk of exudative AMD (hazard ratio [HR] 0.69, 95% confidence interval [CI] 0.50-0.96, P = .029). New users of any NSAIDs (HR = 0.79, 95% CI 0.68-0.93, P = .0039) and aspirin (HR = 0.82, 95% CI 0.70-0.97, P = .018) had a lower risk of nonexudative AMD, although this trend did not persist in longer-term users. The relationship between exudative or nonexudative AMD and the remaining categories of NSAID use were not significant.

CONCLUSION

The overall impact of NSAIDs on AMD incidence is small; however, the lower risk of exudative AMD in longer-term NSAID users may point to a protective effect and deserves further study as a possible mechanism to modulate disease risk.

Mechanisms of Damage to the Gastrointestinal Tract From Nonsteroidal Anti-Inflammatory Drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) can damage the gastrointestinal tract, causing widespread morbidity and mortality. Although mechanisms of damage involve the activities of prostaglandin-endoperoxide synthase 1 (PTGS1 or cyclooxygenase [COX] 1) and PTGS1 (COX2), other factors are involved. We review the mechanisms of gastrointestinal damage induction by NSAIDs via COX-mediated and COX-independent processes. NSAIDs interact with phospholipids and uncouple mitochondrial oxidative phosphorylation, which initiates biochemical changes that impair function of the gastrointestinal barrier. The resulting increase in intestinal permeability leads to low-grade inflammation. NSAID inhibition of COX enzymes, along with luminal aggressors, results in erosions and ulcers, with potential complications of bleeding, protein loss, stricture formation, and perforation. We propose a model for NSAID-induced damage to the gastrointestinal tract that includes these complex, interacting, and inter-dependent factors. This model highlights the obstacles for the development of safer NSAIDs.

Indomethacin elicits proteasomal dysfunctions develops apoptosis through mitochondrial abnormalities

Non-steroidal anti-inflammatory drugs (NSAIDs) are a class of drugs that are mainly used to treat pain, inflammation, and fever via cyclooxygenase-2 (COX-2) inhibition. There are abundant findings that uncover the hidden critical chemotherapeutics potential of NSAIDs in cancer treatment. However, still the precise mechanism by which NSAIDs could be used as an effective anti-tumor agent in the prevention of carcinogenesis is not well understood. Here, we show that indomethacin, a well-known NSAID, induces proteasomal dysfunction that results in accumulation of unwanted proteins, mitochondrial abnormalities, and successively stimulate apoptosis in cells. We observed the interaction of indomethacin with proteasome and noticed the massive accumulation of intracellular ubiquitin-positive proteins, which might be due to the suppression of proteasome activities. Furthermore, we also found that exposure of indomethacin causes the accumulation of critical proteasomal substrates that consequently generate severe mitochondrial abnormalities and prompt up key apoptotic events in cells. Our results demonstrate how indomethacin affects normal proteasomal functions and induces mitochondrial apoptosis in cells. These findings also improve our current understanding of how NSAIDs can exhibit crucial anti-proliferative effects in cells. In near future, our findings may suggest a new possible strategy for the development of specific proteasome inhibitors in conjunction with other chemo-preventive anticancer agents.

Current Topics of Strategy of NSAID-Induced Small Intestinal Lesions

Small intestinal mucosal injuries have been recently recognized as common complications associated with non-steroidal anti-inflammatory drugs (NSAIDs) because video capsule endoscopy and balloon enteroscopy are now available for the detection of small intestinal lesions. Small intestinal injury occurs not in an acid-dependent mechanism but by various factors such as enteric bacteria, bile acids, prostaglandin (PG) deficiency and topical factors (abnormal intestinal mucosal permeability, mitochondrial dysfunction, reactive oxygen species, endoplasmic reticulum stress and so on), and there is no well-established prophylactic approach. Several experimental and clinical studies found the effectiveness of some of the mucoprotective drugs, PG analogs, but not that of acid suppressants. Considering the effect of proton pump inhibitors (PPIs) for upper gastrointestinal (GI) disease and in the small intestine, the following 2 kinds of strategies against NSAID-induced GI injuries may be recommended. In patients with a high risk of upper GI disease (peptic ulcer etc.), simultaneous administration of a PPI (for upper GI disease) and a mucoprotective drug (for small intestine) is needed to prevent NSAID-induced GI injury. In other cases, an effective mucoprotective drug is enough for the protection of the entire digestive tract, that is, starting from the esophagus to the small intestine. These strategies may fulfill both economical and curative effects.

The protective effect of procyanidin against LPS-induced acute gut injury by the regulations of oxidative state

Background

A 2 × 4 factorial arrangement of treatments was used to investigate the protective effect of procyanidin (PCA) against lipopolysaccharide (LPS)-induced acute gut injury by the regulations of oxidative state for a 21-days feeding trial.

Methods

A total of 384 1-days-old broiler chicks were assigned to 8 treatments with 8 replicate of 6 broiler chickens per pen. Broiler chickens fed diets based on 4 levels of dietary PCA (0, 0.05, 0.075 and 0.1 % of the requirements). Half of the birds from each treatment group were challenged with 0.9 % NaCl solution or LPS (250 μg/kg body weight, injection administered) at 16, 18 and 21 days of age.

Results

The results indicated that, prior to LPS challenge, there was no dietary effect on bird growth performance (P > 0.05). The injection of LPS were also not associated with any significant changes in poultry performance (P > 0.05). But LPS injection increased serum diamine oxidase (DAO) level and the malondialdehyde (MDA) content of intestinal mucosa (P < 0.05), cause adverse effects to the morphology of the small intestine (P < 0.05), decreased the glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activity of intestinal mucosa (P < 0.05). When LPS-challenged birds were pretreated with PCA, serum DAO concentration and MDA activity in jejunal and ileal mucosa were dramatically attenuated, and improved the morphology of the small intestine as well (P < 0.05).

Conclusion

In conclusion, PCA is able to prevent LPS-induced oxidative stress response in vivo, improved the morphology of the small intestine. The beneficial effect of PCA may depend on increasing the activity of body’s antioxidant enzymes and scavenging free radical activity.

Mitochondrial dysfunction in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) represents a group of idiopathic disorders characterized by chronic or recurring inflammation of the gastrointestinal tract. While the exact etiology of disease is unknown, IBD is recognized to be a complex, multifactorial disease that results from an intricate interplay of genetic predisposition, an altered immune response, changes in the intestinal microbiota, and environmental factors. Together, these contribute to a destruction of the intestinal epithelial barrier, increased gut permeability, and an influx of immune cells. Given that most cellular functions as well as maintenance of the epithelial barrier is energy-dependent, it is logical to assume that mitochondrial dysfunction may play a key role in both the onset and recurrence of disease. Indeed several studies have demonstrated evidence of mitochondrial stress and alterations in mitochondrial function within the intestinal epithelium of patients with IBD and mice undergoing experimental colitis. Although the hallmarks of mitochondrial dysfunction, including oxidative stress and impaired ATP production are known to be evident in the intestines of patients with IBD, it is as yet unclear whether these processes occur as a cause of consequence of disease. We provide a current review of mitochondrial function in the setting of intestinal inflammation during IBD.

Gastrointestinal dysfunction in autism spectrum disorder: the role of the mitochondria and the enteric microbiome

Autism spectrum disorder (ASD) affects a significant number of individuals worldwide with the prevalence continuing to grow. It is becoming clear that a large subgroup of individuals with ASD demonstrate abnormalities in mitochondrial function as well as gastrointestinal (GI) symptoms. Interestingly, GI disturbances are common in individuals with mitochondrial disorders and have been reported to be highly prevalent in individuals with co-occurring ASD and mitochondrial disease. The majority of individuals with ASD and mitochondrial disorders do not manifest a primary genetic mutation, raising the possibility that their mitochondrial disorder is acquired or, at least, results from a combination of genetic susceptibility interacting with a wide range of environmental triggers. Mitochondria are very sensitive to both endogenous and exogenous environmental stressors such as toxicants, iatrogenic medications, immune activation, and metabolic disturbances. Many of these same environmental stressors have been associated with ASD, suggesting that the mitochondria could be the biological link between environmental stressors and neurometabolic abnormalities associated with ASD. This paper reviews the possible links between GI abnormalities, mitochondria, and ASD. First, we review the link between GI symptoms and abnormalities in mitochondrial function. Second, we review the evidence supporting the notion that environmental stressors linked to ASD can also adversely affect both mitochondria and GI function. Third, we review the evidence that enteric bacteria that are overrepresented in children with ASD, particularly Clostridia spp., produce short-chain fatty acid metabolites that are potentially toxic to the mitochondria. We provide an example of this gut–brain connection by highlighting the propionic acid rodent model of ASD and the clinical evidence that supports this animal model. Lastly, we discuss the potential therapeutic approaches that could be helpful for GI symptoms in ASD and mitochondrial disorders. To this end, this review aims to help better understand the underlying pathophysiology associated with ASD that may be related to concurrent mitochondrial and GI dysfunction.

Reactive oxygen species-scavenging nanomedicines for the treatment of oxidative stress injuries

This Progress Report describes a development of two types of reactive oxygen species (ROS)-scavenging nanomedicines for the treatment of oxidative stress injuries, referred to as pH-sensitive redox nanoparticle (RNP(N) ) and pH-insensitive redox nanoparticle (RNP(O) ), which are prepared by self-assembling amphiphilic block copolymers possessing nitroxide radicals as a side chain of hydrophobic segment via amine and ether linkages, respectively. Due to a protonation of amino groups in hydrophobic core, RNP(N) disintegrates in low pH environments such as ischemic, inflamed, and tumor tissues, resulting in increased ROS-scavenging activity because of the exposed nitroxide radicals from the core. Utilizing pH-responsiveness of RNP(N) , it shows remarkable therapeutic effects on oxidative stress injuries such as renal and cerebral ischemia-reperfusion injuries after intravenous administration. Moreover, RNP(N) shows an enhancement of the activity of anticancer drugs by suppression of activation of transcription factors in tumor due to the ROS scavenging. On the other hand, orally administered RNP(O) has notable characteristics such as preferential accumulation in mucosa and inflamed area of gastrointestinal tract and no uptake into blood stream. Based on these characters, RNP(O) shows a remarkable therapeutic effect for the gastrointestinal inflammation without any adverse effects. Thus, ROS-scavenging nanomedicines have therapeutic efficacy in numerous oxidative stress diseases.

Distinct adipogenic differentiation phenotypes of human umbilical cord mesenchymal cells dependent on adipogenic conditions

The umbilical cord (UC) matrix is a source of multipotent mesenchymal stem cells (MSCs) that have adipogenic potential and thus can be a model to study adipogenesis. However, existing variability in adipocytic differentiation outcomes may be due to discrepancies in methods utilized for adipogenic differentiation. Additionally, functional characterization of UCMSCs as adipocytes has not been described. We tested the potential of three well-established adipogenic cocktails containing IBMX, dexamethasone, and insulin (MDI) plus indomethacin (MDI-I) or rosiglitazone (MDI-R) to stimulate adipocyte differentiation in UCMSCs. MDI, MDI-I, and MDI-R treatment significantly increased peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT-enhancer binding protein alpha (C/EBPα) mRNA and induced lipid droplet formation. However, MDI-I had the greatest impact on mRNA expression of PPARγ, C/EBPα, FABP4, GPD1, PLIN1, PLIN2, and ADIPOQ and lipid accumulation, whereas MDI showed the least. Interestingly, there were no treatment group differences in the amount of PPARγ protein. However, MDI-I treated cells had significantly more C/EBPα protein compared to MDI or MDI-R, suggesting that indomethacin-dependent increased C/EBPα may contribute to the adipogenesis-inducing potency of MDI-I. Additionally, bone morphogenetic protein 4 (BMP4) treatment of UCMSCs did not enhance responsiveness to MDI-induced differentiation. Finally to characterize adipocyte function, differentiated UCMSCs were stimulated with insulin and downstream signaling was assessed. Differentiated UCMSCs were responsive to insulin at two weeks but showed decreased sensitivity by five weeks following differentiation, suggesting that long-term differentiation may induce insulin resistance. Together, these data indicate that UCMSCs undergo adipogenesis when differentiated in MDI, MDI-I, and MDI-R, however the presence of indomethacin greatly enhances their adipogenic potential beyond that of rosiglitazone. Furthermore, our results suggest that insulin signaling pathways of differentiated UCMSCs are functionally similar to adipocytes.

Proanthocyanidin from grape seed extracts protects indomethacin-induced small intestinal mucosal injury

Proanthocyanidin (grape seed proanthocyanidin extracts, GSPEs) is an antioxidant and scavenges free radicals. Excessive oxidative stress and free radical production are major components in the pathogenesis of NSAID-induced small intestinal injury. We investigated the effect of GSPEs on indomethacin-induced intestinal mucosal injury in the rat. Rats were allocated into four groups: the null control group, the indomethacin control group, the low-dose GSPEs group, and the high-dose GSPEs group. GSPEs were administered for 4 days. Then indomethacin and GSPEs were coadministered for the following 2 days by oral route. The dose of indomethacin was 200 mg/Kg. The doses of GSPEs were 100 mg/Kg for low-dose group and 300 mg/Kg for high-dose group. Luminal bleeding was solely observed in one of 5 rats from indomethacin control group. The number of ulcer count was reduced to 0.1 ± 0.3 per rat in GSPEs treated group compared to 1.4 ± 0.5 per rat in indomethacin control group. Submucosal inflammatory cell infiltration was also reduced to 50% in GSPEs treated group. The tissue level of prostaglandin E2 was not affected by GSPEs treatment. GSPEs attenuated the indomethacin-induced small intestinal injury irrespective of the tissue PGE2 depletion and glutathione consumption.

Down-regulation of collagen I biosynthesis in intestinal epithelial cells exposed to indomethacin: a comparative proteome analysis

In contrast to accumulated knowledge about gastroduodenal injury associated with nonsteroidal antiinflammatory drugs (NSAIDs) such as indomethacin, small intestinal mucosal injuries have been noticed only recently, and the precise mechanism remains to be elucidated. To clarify the mechanism, we performed 2-DE on IEC-6 rat normal intestinal cells that were treated with indomethacin (200μΜ, 24h) or a vehicle control and identified 18 up-regulated and 8 down-regulated proteins through MALDI-TOF/TOF mass spectrometry. Among these proteins, collagen I and proteins involved in collagen I biosynthesis and maturation, including prolyl 4-hydroxylase subunit α1, protein disulfide isomerase A3 (PDIA3), calreticulin, and endoplasmin, were all down-regulated by indomethacin. Immunohistochemical staining of the intestinal mucosa of indomethacin-administered rats showed a decrease of collagen I on the apical surface of intestinal cells. Cell death induced by indomethacin was prominently suppressed when IEC-6 cells were grown on collagen I-coated plates. cis-4-Hydroxy-l-proline, a proline analog that inhibits collagen synthesis, depressed IEC-6 cell viability in a concentration-dependent manner. Cell death was also induced by short interfering RNA knockdown of endogenous collagen I in IEC-6 cells. In conclusion, by comparative proteome analysis, we identified down-regulation of collagen I as an important mechanism in NSAID-induced intestinal injury.

BIOLOGICAL SIGNIFICANCE

Small intestinal lesions induced by NSAIDs are of great concern in clinical settings. Various hypotheses have been proposed for the origin of these inflammatory responses, such as reduction in the blood flow, intestinal hypermotility, abnormal intestinal mucosal permeability, mitochondrial dysfunction, and reactive oxygen species, many of which are related to the inhibition of prostaglandin synthesis. However, the precise mechanism is yet to be known. The cellular process of the lesions must involve up- and down-regulations of a large number of proteins and complex interactions between them. To elucidate it, global and systematic identification of the proteins in intestinal cells affected by NSAIDs is essential. We found that the proteins exhibiting reduced expression by indomethacin treatment are collagen I and the proteins involved in collagen I synthesis and maturation. Consistent with this, immunohistochemical analysis showed that the indomethacin-treated rat intestinal mucosal cells exhibits decreased collagen I expression on its apical surface. Furthermore, the cell-protective effect of collagen on intestinal mucosal cells was demonstrated by the use of a collagen-synthesis inhibitor, short interfering RNA (siRNA) knockdown of endogenous collagen I, and cell cultivation on collagen I-coated plates versus uncoated plates. These results give important information on the role of the collagen synthesis in intestinal mucosa in the mechanism of NSAID-induced small intestinal lesions.

Deleterious effects of indomethacin in the mid-gestation human intestine

The use of the anti-inflammatory drug indomethacin (INDO) in preterm infants has been associated with an increased risk of developing enteropathies. In this study, we have investigated the direct impact of INDO on the human mid-gestation intestinal transcriptome using serum-free organ culture. After determining the optimal dose of 1 μM of INDO (90% inhibition of intestinal prostaglandin E2 production and range of circulating levels in treated preterm babies), global gene expression profiles were determined using Illumina bead chip microarrays in both small and large intestines after 48 h of INDO treatment. Using Ingenuity Pathway Analysis software, we identified critical metabolic pathways that were significantly altered by INDO in both intestinal segments including inflammation and also glycolysis, oxidative phosphorylation and free radical scavenging/oxidoreductase activity, which were confirmed by qPCR at the level of individual genes. Taken together, these data revealed that INDO directly exerts multiple detrimental effects on the immature human intestine.

Acetyl salicylic acid induces damage to intestinal epithelial cells by oxidation-related modifications of ZO-1

Acetyl salicylic acid (ASA) is one of the most frequently prescribed medications for the secondary prevention of cardiovascular and cerebrovascular events. It has recently been reported to cause small intestinal mucosal injury at a considerably higher rate than previously believed. The aim of this study is to investigate the mechanism by which this occurs using an in vitro small intestine model focusing on the role of oxidative stress and cell permeability. Differentiated Caco-2 exhibits a phenotype similar to human small intestinal epithelium. We measured whether ASA induced the increase of differentiated Caco-2 permeability, the decrease of tight junction protein expression, the production of reactive oxygen species (ROS), and the expression of ROS-modified zonula occludens-1 (ZO-1) protein. In some experiments, Mn(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP, a superoxide dismutase mimetic) was used. The nontoxic concentration of ASA decreased transepithelial electrical resistance and increased the flux of fluorescein isothiocyanate-conjugated dextran across Caco-2 in a time-dependent manner. The same concentration of ASA significantly decreased ZO-1 expression among TJ proteins as assessed by Western blot and immunocytochemistry and increased ROS production and the expression of oxidative stress-modified ZO-1 protein. However, MnTMPyP suppressed the ASA-induced increased intercellular permeability and the ASA-induced ROS-modified ZO-1 expression. Our findings indicate that ASA-induced ROS production can specifically modify the expression of ZO-1 protein and induce increased cell permeability, which may ultimately cause small intestinal mucosal injury.

Indomethacin-induced translocation of bacteria across enteric epithelia is reactive oxygen species-dependent and reduced by vitamin C

The enteric epithelium must absorb nutrients and water and act as a barrier to the entry of luminal material into the body; this barrier function is a key component of innate immunity. Nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy occurs via inhibition of prostaglandin synthesis and perturbed epithelial mitochondrial activity. Here, the direct effect of NSAIDs [indomethacin, piroxicam (cyclooxygenase 1 and 2 inhibitors), and SC-560 (a cyclooxygenase 1 inhibitor)] on the barrier function of human T84 epithelial cell line monolayers was assessed by transepithelial electrical resistance (TER) and internalization and translocation of a commensal Escherichia coli. Exposure to E. coli in the presence and absence of drugs for 16 h reduced TER; however, monolayers cotreated with E. coli and indomethacin, but not piroxicam or SC-560, displayed significant increases in internalization and translocation of the bacteria. This was accompanied by increased reactive oxygen species (ROS) production, which was also increased in epithelia treated with E. coli only. Colocalization revealed upregulation of superoxide synthesis by mitochondria in epithelia treated with E. coli + indomethacin. Addition of antioxidants (vitamin C or a green tea polyphenol, epigallocathechin gallate) quenched the ROS and prevented the increase in E. coli internalization and translocation evoked by indomethacin, but not the drop in TER. Evidence of increased apoptosis was not observed in this model. The data implicate epithelial-derived ROS in indomethacin-induced barrier dysfunction and show that a portion of the bacteria likely cross the epithelium via a transcellular pathway. We speculate that addition of antioxidants as dietary supplements to NSAID treatment regimens would reduce the magnitude of decreased barrier function, specifically the transepithelial passage of bacteria.

Inhibition of mitochondrial complex I by various non-steroidal anti-inflammatory drugs and its protection by quercetin via a coenzyme Q-like action

Mitochondrial dysfunction plays a major role in the development of oxidative stress and cytotoxicity induced by non-steroidal anti-inflammatory drugs (NSAIDs). A major objective of the present study was to investigate whether in vitro the NSAIDs, aspirin, indomethacin, diclofenac, piroxicam and ibuprofen, which feature different chemical structures, are able to inhibit mitochondrial complex I. All NSAIDs were effective inhibitors when added both, directly to mitochondria isolated from rat duodenum epithelium (50 μM) or to Caco-2 cells (250 μM). In the former system, complex I inhibition was concentration-dependent and susceptible to competition and reversion by the addition of coenzyme Q (32.5-520 μM). Based on reports suggesting a potential gastro-protective activity of quercetin, the ability of this flavonoid to protect isolated mitochondria against NSAIDs-induced complex I inhibition was evaluated. Low micromolar concentrations of quercetin (1-20 μM) protected against such inhibition, in a concentration dependent manner. In the case of aspirin, quercetin (5 μM) increased the IC50 by 10-fold. In addition, the present study shows that quercetin (5-10 μM) can behave as a "coenzyme Q-mimetic" molecule, allowing a normal electron flow along the whole electron transporting chain (complexes I, II, III and IV). The exposed findings reveal that complex I inhibition is a common deleterious effect of NSAIDs at the mitochondrial level, and that such effect is, for all tested agents, susceptible to be prevented by quercetin. Data provided here supports the contention that the protective action of quercetin resides on its, here for first time-shown, ability to behave as a coenzyme Q-like molecule.

Differential protective effects of quercetin, resveratrol, rutin and epigallocatechin gallate against mitochondrial dysfunction induced by indomethacin in Caco-2 cells

The beneficial effects of dietary polyphenols on health are due not only to their antioxidant properties but also to their antibacterial, anti-inflammatory and/or anti-tumoral activities. It has recently been proposed that protection of mitochondrial function (which is altered in several diseases such as Alzheimer, Parkinson, obesity and diabetes) by these compounds, may be important in explaining the beneficial effects of polyphenols on health. The aim of this study was to evaluate the protective effects of dietary polyphenols quercetin, rutin, resveratrol and epigallocatechin gallate against the alterations of mitochondrial function induced by indomethacin (INDO) in intestinal epithelial Caco-2 cells, and to address the mechanism involved in such damaging effect by INDO, which generates oxidative stress. INDO concentration dependently decreases cellular ATP levels and mitochondrial membrane potential in Caco-2 cells after 20min of incubation. INDO also inhibits the activity of mitochondrial complex I and causes accumulation of NADH; leading to overproduction of mitochondrial O(2)()(-), since it is prevented by pyruvate. Quercetin (0.01mg/ml), resveratrol (0.1mg/ml) and rutin (1mg/ml) protected Caco-2 cells against INDO-induced mitochondrial dysfunction, while no protection was observed with epigallocatechin gallate. Quercetin was the most efficient in protecting against mitochondrial dysfunction; this could be due to its ability to enter cells and accumulate in mitochondria. Additionally its structural similarity with rotenone could favor its binding to the ubiquinone site of complex I, protecting it from inhibitors such as INDO or rotenone. These findings suggest a possible new protective role for dietary polyphenols for mitochondria, complementary of their antioxidant property. This new role might expand the preventive and/or therapeutic use of PPs in conditions involving mitochondrial dysfunction and associated with increased oxidative stress at the cellular or tissue levels.

Apple peel polyphenol extract protects against indomethacin-induced damage in Caco-2 cells by preventing mitochondrial complex I inhibition

The aim of this work was to investigate the role of mitochondrial dysfunction in the development of oxidative stress and cytotoxicity induced by indomethacin and to evaluate the potential of an apple peel polyphenol extract (APPE) in protecting against these events. Indomethacin induced, time-dependently, mitochondrial and oxidative perturbations which led to cell losses. An inhibition of complex I activity, shown for first time here, which resulted in a concomitant drop in cellular ATP and an increment in mitochondrial superoxide production, was observed after 10 min of exposure. These early cytotoxicity-triggering events were followed by an increase in the intracellular production of superoxide (20 min), an elevation in the activity of xanthine oxidase which led to an increased lipid peroxidation (30 min), and a decline in cell viability which manifested after 40 min. These events were selectively prevented using allopurinol, tempol and APPE (a standardized apple peel polyphenol extract). While the oxidative and cell lytic effects of indomethacin were equally prevented by the three agents, only APPE protected against complex I inhibition and its downstream oxidative consequences. Since tempol (a SOD mimetic) prevented the elevation in xanthine oxidase activity, and allopurinol (a xanthine oxidase inhibitor) totally abolished the increment in lipid peroxidation and loss of cell viability, it appears that a superoxide-dependent increase in xanthine oxidase activity is critical to trigger cytotoxicity. Thus, preventing the early increment in superoxide formation that, as a result of inhibiting complex I, takes place within mitochondria would be key toward protecting the cells against the oxidative and cytolytic effects of indomethacin. The ability of APPE in preventing the inhibition of complex I and the subsequent superoxide-dependent increase in XO activity warrants further studies to evaluate the mechanism involves in the protecting effect of APPE against the indomethacin-associated adverse effects in vivo.

Is metabolic stress a common denominator in inflammatory bowel disease?

The enteric epithelium represents the major boundary between the outside world and the body, and in the colon it is the interface between the host and a vast and diverse microbiota. A common feature of inflammatory bowel disease (IBD) is decreased epithelial barrier function, and while a cause-and-effect relationship can be debated, prolonged loss of epithelial barrier function (whether this means the ability to sense bacteria or exclude them) would contribute to inflammation. While there are undoubtedly individual nuances in IBD, we review data in support of metabolic stress--that is, perturbed mitochondrial function--in the enterocyte as a contributing factor to the initiation of inflammation and relapses in IBD. The postulate is presented that metabolic stress, which can arise as a consequence of a variety of stimuli (e.g., infection, bacterial dysbiosis, and inflammation also), will reduce epithelial barrier function and perturb the enterocyte-commensal flora relationship and suggest that means to negate enterocytic metabolic stress should be considered as a prophylactic or adjuvant therapy in IBD.

Enhanced translocation of bacteria across metabolically stressed epithelia is reduced by butyrate

BACKGROUND

The gut microflora in some patients with Crohn's disease can be reduced in numbers of butyrate-producing bacteria and this could result in metabolic stress in the colonocytes. Thus, we hypothesized that the short-chain fatty acid, butyrate, is important in the maintenance and regulation of the barrier function of the colonic epithelium.

METHODS

Confluent monolayers of the human colon-derived T84 or HT-29 epithelial cell lines were exposed to dinitrophenol (DNP (0.1 mM), uncouples oxidative phosphorylation) + Escherichia coli (strain HB101, 10(6) cfu) +/- butyrate (3-50 mM). Transepithelial resistance (TER), and bacterial internalization and translocation were assessed over a 24-hour period. Epithelial ultrastructure was assessed by transmission electron microscopy.

RESULTS

Epithelia under metabolic stress display decreased TER and increased numbers of pseudopodia that is consistent with increased internalization and translocation of the E. coli. Butyrate (but not acetate) significantly reduced the bacterial translocation across DNP-treated epithelia but did not ameliorate the drop in TER in the DNP+E. coli exposed monolayers. Inhibition of bacterial transcytosis across metabolically stressed epithelia was associated with reduced I-kappaB phosphorylation and hence NF-kappaB activation.

CONCLUSIONS

Reduced butyrate-producing bacteria could result in increased epithelial permeability particularly in the context of concomitant exposure to another stimulus that reduces mitochondria function. We speculate that prebiotics, the substrate for butyrate synthesis, is a valuable prophylaxis in the regulation of epithelial permeability and could be of benefit in preventing relapses in IBD.

Assessment and prevention of gastrointestinal toxicity of non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for analgesic, anti-inflammatory and, in the case of aspirin, for anti-thrombotic actions. The serious gastrointestinal side-effects associated with these drugs are of concern and pose a significant obstacle to their use. This review discusses the pathogenic mechanisms by which the conventional acidic NSAIDs induce gastrointestinal toxicity, with particular emphasis on non-prostaglandin effects. Methods of assessment of NSAID-induced enteropathy are reviewed, with particular emphasis on the use of functional measurement of NSAID-induced changes in the gastrointestinal tract. The advances in our knowledge of the pathogenesis of these effects have resulted in the development of a range of novel NSAIDs. Where functional assessment of the effects of NSAIDs has been employed, it appears to be more useful as an indicator of early-stage changes rather than a predictor of the effects of long-term NSAID exposure. Successful pharmaceutical strategies now offer considerable promise for reducing the severity of NSAID damage to the gastrointestinal tract. The utility of intestinal permeability measurements for selection and assessment of these strategies is discussed.

Metabolic stress evokes decreases in epithelial barrier function

The epithelial lining of the gastrointestinal tract is the major interface between the external world (e.g., the gut lumen) and the body, and as such the proper maintenance and regulation of epithelial barrier function is a key determinant of digestive health and host well-being. Many enteropathies are associated with increased gut permeability, including inflammatory bowel disease (IBD). Maintaining the barrier function of the epithelium, independent of whether paracellular or transcellular permeation pathways are considered, is an energy-dependent process. Here we present an overview of the impact that metabolic stress (e.g., reductions in epithelial ATP synthesis) can have on permeability characteristics of epithelial monolayers and show that metabolic stress in the presence of a commensal flora results in a significant loss of epithelial integrity, and that this increase in epithelial permeability can be enhanced by the presence of tumor necrosis factor-alpha (TNFalpha). We speculate that the combination of these factors in vivo would result in significant perturbations in epithelial barrier function that could be of pathophysiological significance and contribute to the initiation of IBD or the induction of disease relapses.

Orengedokuto and berberine improve indomethacin-induced small intestinal injury via adenosine

BACKGROUND

Recent endoscopic technology has revealed that small intestinal injury is a serious threat to patients receiving nonsteroidal anti-inflammatory drugs (NSAIDs). We previously showed that Japanese herbal medicine, Orengedokuto (OGT; Huang-Lian-Jie-Du-Tang in Chinese), protects mice from lethal indomethacin (IND)-induced enteropathy. To elucidate the mechanism of the protective effect of OGT, we performed microarray analyses and high power statistical analyses of microarray data using new bioinformatics tools.

METHODS

Female BALB/c mice were subcutaneously injected with IND (20 mg/kg) once a day for 2 days. OGT-treated mice received a diet containing OGT from the first IND injection until the end of the experiment. Gene expression signals of small intestine were obtained with GeneChip. Analyses for overrepresentation of Gene Ontology categories were conducted using MetaGene Profiler (MGP) and the changes were visualized by Cell Illustrator Online (CIO). Furthermore, active ingredients of OGT were investigated.

RESULTS

MGP and CIO suggested a critical role for the adenosine system, especially adenosine deaminase (ADA), a key enzyme of adenosine catabolism. Quantitative real time RT-PCR and in situ hybridization showed that OGT decreased the expression of ADA, which possibly resulted in the elevation of the anti-inflammatory nucleoside adenosine. Blockade of the adenosine A2a receptor abrogated the protective effect of OGT. Berberine, a major ingredient of OGT, suppressed ADA expression and reduced the incidence of lethality.

CONCLUSIONS

OGT may prevent IND-induced enteropathy by decreasing ADA which results in the elevation of adenosine. Modulation of the adenosine system may be an efficient therapeutic strategy for NSAID-induced enteropathy.

Rescue strategies against non-steroidal anti-inflammatory drug-induced gastroduodenal damage

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most commonly prescribed drugs worldwide, which attests to their efficacy as analgesic, antipyretic and anti-inflammatory agents as well as anticancer drugs. However, NSAID use also carries a risk of major gastroduodenal events, including symptomatic ulcers and their serious complications that can lead to fatal outcomes. The development of "coxibs" (selective cyclooxygenase-2 [COX-2] inhibitors) offered similar efficacy with reduced toxicity, but this promise of gastroduodenal safety has only partially been fulfilled, and is now dented with associated risks of cardiovascular or intestinal complications. Recent advances in basic science and biotechnology have given insights into molecular mechanisms of NSAID-induced gastroduodenal damage beyond COX-2 inhibition. The emergence of newer kinds of NSAIDs should alleviate gastroduodenal toxicity without compromising innate drug efficacy. In this review, novel strategies for avoiding NSAID-associated gastroduodenal damage will be described.

Effect of fat feeding on pro-oxidant and anti-oxidant enzyme systems in rat intestine: possible role in the turnover of enterocytes

Immature epithelial cells generated in the crypt base undergo differentiation while progressing to the villus tip, where the cells upon apoptosis are detached from the underlying muscular tissue. We previously reported that lipid peroxidation might be involved in the turnover of enterocytes across the crypt-villus axis in rat intestine (Dig Dis Sci 52:1840-1844, 2007). To examine whether long-term feeding of fat with different fatty-acid composition influences this process, in the present study we investigated the effect of feeding fish oil (n - 3) and corn oil (n - 6) polyunsaturated fatty acids on lipid per-oxidation and anti-oxidant systems in different epithelial cell fractions isolated in rat intestine. Feeding fish oil or corn oil markedly enhanced lipid per-oxidation levels of enterocytes throughout villus height compared with control, but there was no difference in the distribution profile of pro- and anti-oxidant enzyme systems and lipid per-oxidation across the crypt-villus axis under these conditions. Analysis of lipid peroxidation levels in different cell fractions revealed that the thiobarbituric acid reactive substance were 9- to 11-fold higher at the villus tip compared with at the crypt base. The activities of glutathione reductase and glutathione-S-transferase were 2- to 5-fold higher in villus tip compared to the crypt region. However, the activities of superoxide dismutase and catalase were 6- to 8-fold high at the crypt base compared with at villus tip cells. Immunocytolocalization of superoxide dismutase showed high staining in crypt base compared with that in villus, tip cells. These findings further suggest that generation of reactive oxygen species in enterocytes across the crypt-villus axis may be involved in turnover of enterocytes across the crypt-villus unit in rat intestine.