Metronidazole reduces intestinal inflammation and blood loss in non-steroidal anti-inflammatory drug induced enteropathy

Metronidazole may display anti-inflammatory features in periodontitis treatment: A scoping review

AIM

Metronidazole (MTZ) is an antimicrobial agent used to treat anaerobic infections. It has been hypothesized that MTZ may also have anti-inflammatory properties, but the evidence is limited and has not been previously reviewed. Thus, this scoping review aimed to answer the following question: "What is the evidence supporting anti-inflammatory properties of metronidazole that are not mediated by its antimicrobial effects?"

METHODS

A scoping review was conducted according to the PRISMA-ScR statement. Five databases were searched up to January 2023 for studies evaluating the anti-inflammatory properties of MTZ used as monotherapy for treating infectious and inflammatory diseases.

RESULTS

A total of 719 records were identified, and 27 studies (21 in vivo and 6 in vitro) were included. The studies reported experimental evidence of MTZ anti-inflammatory effects on (1) innate immunity (barrier permeability, leukocyte adhesion, immune cell populations), (2) acquired immunity (lymphocyte proliferation, T-cell function, cytokine profile), and (3) wound healing/resolution of inflammation.

CONCLUSION

Taken together, this scoping review supported a potential anti-inflammatory effect of MTZ in periodontitis treatment. We recommend that future clinical studies should be conducted to evaluate specific MTZ anti-inflammatory pathways in the treatment of periodontitis.

The impact of metronidazole on pain persistence after fertility-sparing endometriosis surgery: METROFERT randomized study

BACKGROUND

Recent studies have shown that a disrupted microbiome is associated with endometriosis. Despite endometriosis affecting 1 in 10 reproductive-aged women, there is a lack of innovative and nonhormonal long-term effective treatments. Studies have reported an approximately 20% to 37.5% persistence of pain after fertility-sparing endometriosis surgery. Metronidazole has been shown to decrease inflammatory markers and the size of endometriosis lesions in animal studies.

OBJECTIVE

To determine if modulating the microbiome with oral metronidazole for 14 days after fertility-sparing endometriosis surgery decreases pain persistence postoperatively.

STUDY DESIGN

This was a randomized, multicenter, placebo-controlled, double-blind trial. Individuals 18 to 50 years old were prospectively randomized to placebo vs oral metronidazole for 14 days immediately after endometriosis fertility-sparing excision surgery. The primary outcome was binary, subjective pain persistence at 6 weeks postoperatively. Secondary outcomes included quality of life, sexual function, and endometriosis-associated pain scores according to the Endometriosis Health Profile-5, Female Sexual Function Index, and a visual analog scale.

RESULTS

One hundred fifty-two participants were approached from October 2020 to October 2023 to enroll in the study. Sixty-four participants were excluded either because they did not meet inclusion or exclusion criteria or because they declined to participate. Eighty-eight participants were randomized in a 1:1 ratio to receive either the oral placebo or metronidazole after endometriosis excision surgery; 18.2% of participants were lost to follow-up or discontinued treatment and this was not significantly different between the 2 arms, yielding a final cohort of 72 participants. Baseline demographics of the 2 study groups were similar. There was no statistically significant improvement in the primary outcome of binary subjective pain persistence between the metronidazole group compared to placebo (84% vs 88%, P=.74) at 6 weeks postoperatively. Further, no significant differences between treatments were detected in the secondary outcomes.

CONCLUSION

A postoperative 14-day regimen of oral metronidazole immediately after fertility-sparing endometriosis surgery was not associated with any significant differences between treatment groups in the persistence of endometriosis-related pain symptoms compared to placebo at 6 weeks.

Use of Saccharomyces boulardii CNCM I-745 as therapeutic strategy for prevention of nonsteroidal anti-inflammatory drug-induced intestinal injury

BACKGROUND AND PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. This study examined the protective effects of the probiotic Saccharomyces boulardii CNCM I-745 in a rat model of diclofenac-induced enteropathy.

EXPERIMENTAL APPROACH

Enteropathy was induced in 40-week-old male rats by intragastric diclofenac (4 mg·kg-1 BID for 14 days). S. boulardii CNCM I-745 (3 g·kg-1 BID by oral gavage) was administered starting 14 days before (preventive protocol) or along with (curative protocol) diclofenac administration. Ileal damage, inflammation, barrier integrity, gut microbiota composition and toll-like receptors (TLRs)-nuclear factor κB (NF-κB) pathway were evaluated.

KEY RESULTS

Diclofenac elicited intestinal damage, along with increments of myeloperoxidase, malondialdehyde, tumour necrosis factor and interleukin-1β, overexpression of TLR2/4, myeloid differentiation primary response 88 (Myd88) and NF-κB p65, increased faecal calprotectin and butyrate levels, and decreased blood haemoglobin levels, occludin and butyrate transporter monocarboxylate transporter 1 (MCT1) expression. In addition, diclofenac provoked a shift of bacterial taxa in both faecal and ileal samples. Treatment with S. boulardii CNCM I-745, in both preventive and curative protocols, counteracted the majority of these deleterious changes. Only preventive administration of the probiotic counteracted NSAID-induced decreased expression of MCT1 and increase in faecal butyrate levels. Occludin expression, after probiotic treatment, did not significantly change.

CONCLUSIONS AND IMPLICATIONS

Treatment with S. boulardii CNCM I-745 prevents diclofenac-induced enteropathy through anti-inflammatory and antioxidant activities. Such effects are likely to be related to increased tissue butyrate bioavailability, through an improvement of butyrate uptake by the enteric mucosa.

Review article: drug-induced small bowel injury

BACKGROUND

Drug-induced gastrointestinal injury has been increasingly reported, but its exact incidence is not known. The small and large intestines represent the most affected sites of injury, accounting for 20%-40% of all gastrointestinal side effects.

AIM

To provide an updated literature review detailing medications linked to the development of small bowel injury.

METHODS

We conducted a literature search on PubMed from its inception to May 1, 2021. We included English-language original studies, meta-analyses, systematic reviews, review articles and case reports.

RESULTS

Drug-induced enteropathy can range from asymptomatic histological changes resulting in a subtle, self-limited disease to a chronic inflammatory condition mimicking inflammatory bowel disease, or bowel perforation. Endoscopy can demonstrate erythema, mucosal friability, oedema, erosions, ulcers or strictures in severe cases. Histology may include mucosal erosions and ulcerations, focal active enteritis, villous atrophy, epithelial apoptosis or necrotising enteritis. A well-established association has been found with the use of nonsteroidal anti-inflammatory drugs, immunosuppressants, chemotherapeutic agents, antibiotics, immunotherapies, etanercept and olmesartan. Possible associations have been reported with other biologic agents, medications used for glycemic control, antihypertensives, cholinesterase inhibitors, potassium and iron supplements, with conflicting data regarding contraceptives/hormonal therapy and isotretinoin.

CONCLUSION

Physicians should be aware of the manifestations of drug-induced enteropathy as early recognition can lead to prompt discontinuation of the offending therapy and, therefore, a reduced risk of future complications.

The role of gut and genital microbiota and the estrobolome in endometriosis, infertility and chronic pelvic pain

BACKGROUND

Endometriosis is a chronic, burdensome condition that is historically understudied. Consequently, there is a lack of understanding of the etiology of the disease and its associated symptoms, including infertility and chronic pelvic pain (CPP). Endometriosis development is influenced by estrogen metabolism and inflammation, which are modulated by several factors including the microbiome and the estrobolome (the collection of genes encoding estrogen-metabolizing enzymes in the gut microbiome). Therefore, there is increasing interest in understanding the role of microbiota in endometriosis etiology.

OBJECTIVE AND RATIONALE

To date, there is no cure for endometriosis and treatment options often are ineffective. This manuscript will review the potential relationship between the microbiome and endometriosis, infertility and CPP and highlight the available data on the microbiome in relation to endometriosis and its related symptoms. The overarching goal of this manuscript is to inform future microbiome research that will lead to a deeper understanding of the etiology of the disease and possible diagnostic modalities and treatments. The potential impact of the microbiome on estrogen regulation modulated by the estrobolome, as well as inflammation and other endometriosis-promoting mechanisms within the genital tract, will be reviewed. The methodological limitations of microbiome-related studies will be critically assessed to provide improved guidelines for future microbiome and clinical studies.

SEARCH METHODS

PubMed databases were searched using the following keywords: endometriosis AND microbiome, infertility AND microbiome, pelvic pain AND microbiome, IVF (in-vitro fertilization) AND microbiome, endometriosis AND infertility. Clinical and preclinical animal trials that were eligible for review, and related to microbiome and endometriosis, infertility or CPP were included. All available manuscripts were published in 2002-2021.

OUTCOMES

In total, 28 clinical and 6 animal studies were included in the review. In both human and animal studies, bacteria were enriched in endometriosis groups, although there was no clear consensus on specific microbiota compositions that were associated with endometriosis, and no studies included infertility or CPP with endometriosis. However, bacterial vaginosis-associated bacteria and Lactobacillus depletion in the cervicovaginal microbiome were associated with endometriosis and infertility in the majority (23/28) of studies. Interpretation of endometrial studies is limited owing to a variety of methodological factors, discussed in this review. In addition, metadata outlining antibiotic usage, age, race/ethnicity, menopausal status and timing of sample collection in relation to diagnosis of endometriosis was not consistently reported. Animal studies (6/6) support a bidirectional relationship between the gut microbiota and endometriosis onset and progression.

WIDER IMPLICATIONS

There is evidence that a dysbiotic gut or genital microbiota is associated with multiple gynecologic conditions, with mounting data supporting an association between the microbiome and endometriosis and infertility. These microbiomes likely play a role in the gut-brain axis, which further supports a putative association with the spectrum of symptoms associated with endometriosis, including infertility and CPP. Collectively, this review highlights the demand for more rigorous and transparent methodology and controls, consistency across the field, and inclusion of key demographic and clinical characteristics of disease and comparison participants. Rigorous study designs will allow for a better understanding of the potential role of the microbiome in endometriosis etiology and the relationship to other disorders of the female reproductive tract.

Potential Strategies in the Prevention of Nonsteroidal Anti-inflammatory Drugs-Associated Adverse Effects in the Lower Gastrointestinal Tract

With the increasing use of nonsteroidal anti-inflammatory drugs (NSAIDs), the incidence of lower gastrointestinal (GI) complications is expected to increase. However, unlike upper GI complications, the burden, pathogenesis, prevention and treatment of NSAID-associated lower GI complications remain unclear. To date, no cost-effective and safe protective agent has been developed that can completely prevent or treat NSAID-related lower GI injuries. Selective COX-2 inhibitors, misoprostol, intestinal microbiota modulation, and some mucoprotective agents have been reported to show protective effects on NSAID-induced lower GI injuries. This review aims to provide an overview of the current evidence on the prevention of NSAID-related lower GI injuries.

Gut Microbiota in NSAID Enteropathy: New Insights From Inside

As a class of the commonly used drugs in clinical practice, non-steroidal anti-inflammatory drugs (NSAIDs) can cause a series of adverse events including gastrointestinal injuries. Besides upper gastrointestinal injuries, NSAID enteropathy also attracts attention with the introduction of capsule endoscopy and double balloon enteroscopy. However, the pathogenesis of NSAID enteropathy remains to be entirely clarified. Growing evidence from basic and clinical studies presents that gut microbiota is a critical factor in NSAID enteropathy progress. We have reviewed the recent data about the interplay between gut microbiota dysbiosis and NSAID enteropathy. The chronic medication of NSAIDs could change the composition of the intestinal bacteria and aggravate bile acids cytotoxicity. Meanwhile, NSAIDs impair the intestinal barrier by inhibiting cyclooxygenase and destroying mitochondria. Subsequently, intestinal bacteria translocate into the mucosa, and then lipopolysaccharide released from gut microbiota combines to Toll-like receptor 4 and induce excessive production of nitric oxide and pro-inflammatory cytokines. Intestinal injuries present in the condition of intestinal inflammation and oxidative stress. In this paper, we also have reviewed the possible strategies of regulating gut microbiota for the management of NSAID enteropathy, including antibiotics, probiotics, prebiotics, mucosal protective agents, and fecal microbiota transplant, and we emphasized the adverse effects of proton pump inhibitors on NSAID enteropathy. Therefore, this review will provide new insights into a better understanding of gut microbiota in NSAID enteropathy.

Efficacy of postoperative oral metronidazole for haemorrhoidectomy pain: a randomized double-blind, placebo-controlled trial

AIM

The aim of this work was to examine the efficacy of oral metronidazole in reducing posthaemorrhoidectomy pain versus placebo.

METHOD

Forty patients were randomized to either metronidazole and standard care or placebo and standard care (21 metronidazole, 19 placebo) in a double-blinded, randomized controlled trial. The main outcome measure was posthaemorrhoidectomy pain scores over 21 days, measured on a 10-point Likert scale.

RESULTS

There were no significant differences between groups with regards to age, gender, smoking status, self-reported general health or quality of life, haemorrhoid-related pain, haemorrhoid-related impact on quality of life, reported satisfaction with surgery, experience of surgery, median overall pain score or likelihood of recommending surgery to others. For reported median worst pain scores and defaecation-related pain, a trend to significance was identified between groups on days 16 and 18-21, with the metronidazole group reporting less pain. However, these differences were not significant when prespecified Bonferroni correction criteria were used. Using multilevel mixed effects modelling, the impact of time on median worst pain score was identified to be highly significant (P < 0.0001) whereas treatment allocation (placebo versus metronidazole) did not significantly affect the improvement in patients' reported pain (P = 0.8837).

CONCLUSION

Our data do not support the hypothesis that postoperative metronidazole has a clinically meaningful effect on posthaemorrhoidectomy pain. This study adds to the previous literature, and implies that it should not be routinely used as an adjunct to analgesia.

The Protective Effect of 5-Aminosalicylic Acid Against Non-Steroidal Anti-Inflammatory Drug-Induced Injury Through Free Radical Scavenging in Small Intestinal Epithelial Cells

Background and objectives: Non-steroidal anti-inflammatory drugs (NSAIDs) have been among the major causes of small intestinal injury in clinical practice. As such, the current study investigated the protective effect of 5-aminosalicylic acid (5-ASA) against an NSAID-induced small intestinal injury. Materials and Methods: IEC-6 cells were treated with various concentrations of indomethacin with or without 5-ASA in a serum-free medium, after which an 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Dromide (MTT) assay, a cell apoptosis assay, a caspase-3 activity assay, a reactive oxygen species (ROS) content and Superoxide dismutase 2 (SOD2) activity measurement, a Western blotting for occludin and zonula occludens-1 (ZO-1) and a wound healing assay were conducted. Results: 5-ASA ameliorated indomethacin-induced cell apoptosis and an increase in the intracellular ROS content while augmenting the indomethacin-induced suppression of SOD2 activity in IEC-6 cells. Moreover, 5-ASA reversed the indomethacin-induced attenuation of occludin and ZO-1 expression and promoted faster wound healing effects in IEC-6 cells following an indomethacin-induced injury. Conclusions: Our results suggested that 5-ASA protects small intestinal cells against an NSAID-induced small intestinal injury by scavenging free radicals. Therefore, 5-ASA could be a potential treatment for an NSAID-induced small intestinal injury.

Current knowledge on non-steroidal anti-inflammatory drug-induced small-bowel damage: a comprehensive review

Recent advances in small-bowel endoscopy such as capsule endoscopy have shown that non-steroidal anti-inflammatory drugs (NSAIDs) frequently damage the small intestine, with the prevalence rate of mucosal breaks of around 50% in chronic users. A significant proportion of patients with NSAIDs-induced enteropathy are asymptomatic, but some patients develop symptomatic or complicated ulcers that need therapeutic intervention. Both inhibition of prostaglandins due to the inhibition of cyclooxygenases and mitochondrial dysfunction secondary to the topical effect of NSAIDs play a crucial role in the early process of injury. As a result, the intestinal barrier function is impaired, which allows enterobacteria to invade the mucosa. Gram-negative bacteria and endogenous molecules coordinate to trigger inflammatory cascades via Toll-like receptor 4 to induce excessive expression of cytokines such as tumor necrosis factor-α and to activate NLRP3 inflammasome, a multiprotein complex that processes pro-interleukin-1β into its mature form. Finally, neutrophils accumulate in the mucosa, resulting in intestinal ulceration. Currently, misoprostol is the only drug that has a proven beneficial effect on bleeding small intestinal ulcers induced by NSAIDs or low-dose aspirin, but its protection is insufficient. Therefore, the efficacy of the combination of misoprostol with other drugs, especially those targeting the innate immune system, should be assessed in the next step.

[NSAID enteropathy]

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most commonly used drugs in the world, and their side effects are very high. First of all, these are NSAID gastropathy, but in the long term, 5070% of NSAIDs cause damage to the small intestine (NSAID enteropathy), sometimes with serious consequences. To date, no drugs have been proposed with proven effectiveness to prevent this side effect. Apparently, this is not due to the fully clarified mechanism of pathogenesis. The most promising is the hypothesis of the participation of individual representatives of microflora in the development of enteropathy. Therefore, modulating the intestinal flora with the help of probiotics can be the basic therapeutic strategy for the prevention and treatment of such damage.

NSAID-Gut Microbiota Interactions

Nonsteroidal anti-inflammatory drugs (NSAID)s relieve pain, inflammation, and fever by inhibiting the activity of cyclooxygenase isozymes (COX-1 and COX-2). Despite their clinical efficacy, NSAIDs can cause gastrointestinal (GI) and cardiovascular (CV) complications. Moreover, NSAID use is characterized by a remarkable individual variability in the extent of COX isozyme inhibition, therapeutic efficacy, and incidence of adverse effects. The interaction between the gut microbiota and host has emerged as a key player in modulating host physiology, gut microbiota-related disorders, and metabolism of xenobiotics. Indeed, host-gut microbiota dynamic interactions influence NSAID disposition, therapeutic efficacy, and toxicity. The gut microbiota can directly cause chemical modifications of the NSAID or can indirectly influence its absorption or metabolism by regulating host metabolic enzymes or processes, which may have consequences for drug pharmacokinetic and pharmacodynamic properties. NSAID itself can directly impact the composition and function of the gut microbiota or indirectly alter the physiological properties or functions of the host which may, in turn, precipitate in dysbiosis. Thus, the complex interconnectedness between host-gut microbiota and drug may contribute to the variability in NSAID response and ultimately influence the outcome of NSAID therapy. Herein, we review the interplay between host-gut microbiota and NSAID and its consequences for both drug efficacy and toxicity, mainly in the GI tract. In addition, we highlight progress towards microbiota-based intervention to reduce NSAID-induced enteropathy.

Drug-Induced Small Bowel Injury: a Challenging and Often Forgotten Clinical Condition

PURPOSE OF REVIEW

Most drugs are given by the oral route. Oral intake allows direct contact between the drug and the entire GI tract mucosa, exposing it to potential topical damage until absorption. Medication-induced GI symptoms and lesions are therefore commonly encountered in clinical practice. This review will examine the most common drugs or classes of drugs affecting small bowel function and/or structure.

RECENT FINDINGS

Since non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used medicines, NSAID enteropathy is highly prevalent and brings about considerable morbidity. Antimicrobials and proton-pump inhibitors profoundly modify intestinal microbiota, affecting gut sensory and motor functions, while other drugs (like iron and gold derivatives) impair intestinal permeability. Olmesartan (and likely ACE inhibitors) induce villous atrophy and consequent malabsorption. Mycophenolate mofetil, cancer chemotherapeutic agents, and immune checkpoint inhibitors cause intestinal inflammation, abdominal pain, and diarrhea. Potassium chloride supplements may induce small bowel ulceration, stenosis, and perforation while the cotraceptive pill and anticoagulants are associated with intestinal ischemia and spontaneous intramural hematoma, respectively. In clinical practice, a deep knowledge of clinical pharmacology and toxicology and a high degree of suspicion of drug-related adverse events are mandatory. Only then, the practicing physician will be able to diagnose medication-induced small bowel lesions correctly and will implement the best strategies to treat them.

Effectiveness of acid suppressants and other mucoprotective agents in reducing the risk of occult gastrointestinal bleeding in nonsteroidal anti-inflammatory drug users

Acid suppressants such as histamine-2 receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) are effective in preventing gastrointestinal (GI) bleeding in nonsteroidal anti-inflammatory drugs (NSAIDs) users. Despite widespread acid suppressant use, there remain concerns about several potential risks of long-term use. Therefore, we investigated whether gastroprotective agents (GPAs) other than acid suppression therapy are effective in preventing NSAID-related GI injury. To this end, we studied 9,133 patients with osteoarthritis or rheumatoid arthritis who used NSAIDs for ≥1 month. A decrease of 2 g/dL or more in the hemoglobin level was considered a GI injury indicator. The GPAs included acid suppressants and other mucoprotective agents. Acid suppressants included PPIs and H2RAs. Other mucoprotective agents included misoprostol, rebamipide, and eupatilin. During a median follow-up period of 27 (range, 4.3-51.3) weeks, occult GI bleeding occurred in 1,191 (13%) patients. A comparison of patients who used GPAs concomitantly with that of nonusers in a multivariable analysis revealed the hazard ratios (HRs; 95% confidence intervals [CIs]) for occult GI bleeding were 0.30 (0.20-0.44), 0.35 (0.29-0.43), 0.47 (0.23-0.95), 0.43 (0.35-0.51), and 0.98 (0.86-1.12) for PPIs, H2RAs, misoprostol, rebamipide, and eupatilin, respectively. Compared to PPI co-treatment, H2RA, misoprostol, rebamipide, and eupatilin co-treatments were associated with occult GI bleeding HRs (95% CIs) of 1.19 (0.79-1.79), 1.58 (0.72-3.46), 1.44 (0.96-2.16), and 3.25 (2.21-4.77), respectively. Our findings suggest that mucoprotective agents, such as rebamipide and misoprostol, as well as acid suppressants, are effective in reducing the risk for GI injury in NSAID users.

The Spectrum of Small Intestinal Lesions in Patients with Unexplained Iron Deficiency Anemia Detected by Video Capsule Endoscopy

Background and objectives: Video-capsule endoscopy (VCE) has shown a large range (38⁻83%) of diagnostic yield in unexplained iron deficiency anemia (IDA) and obscure-occult bleeding. Therefore, we retrospectively investigated the VCE-detected spectrum and the prevalence of small bowel injuries and associated risk factors in inpatients with both of the above reported conditions. Methods: We selected inpatients with IDA (hemoglobin <12 g/dL in women, <13 g/dL in men) and obscure-occult bleeding. We excluded VCE indications other than IDA. Complete medical histories and laboratory tests were collected. All subjects underwent PillCam SB2/SB3. The VCE feature Lewis score was calculated when appropriate. We used the t-test and Fisher's exact test for continuous and categorical variables, respectively, in univariate analysis. For multivariate analysis, we used binomial logistic regression. Results: We retrieved 109 patients (female:male ratio of 53:56; age 63.4 ± 18.9 years). Eighty patients (73.4%) showed ≥1 small bowel lesions. The Lewis score was calculated in 41 patients: 13 (31.7%) showed a mild (<135) and 28 (68.3%) a moderate-severe (135⁻790 and >790, respectively) score. In univariate analysis, the small bowel transit time (6.2 ± 2.9 versus 5.2 ± 2.1 h; p = 0.049) and non-steroidal anti-inflammatory drug use for at least two weeks (17.5% versus 0%; p = 0.01) were significantly higher in subjects with injuries. These associations were not confirmed at multivariate analysis. The severity of a lesion directly correlated with proton pump inhibitor (PPI) use and duration (not confirmed in multivariate analysis). VCE can reveal the source of obscure-occult bleeding in a high percentage of unexplained IDAs. A wide spectrum of endoscopic pictures may be found. Known as well as supposed risk factors for small bowel lesions may be detected.

Fluoropyrimidine-induced intestinal mucosal injury is associated with the severity of chemotherapy-related diarrhea

BACKGROUND AND AIM

Although the fluoropyrimidines are effective chemotherapeutic agents for malignant gastrointestinal tumors, they sometimes cause enteritis with diarrhea. Severe treatment-related diarrhea may result in chemotherapy discontinuation. We investigated the relationship between diarrhea severity and fluoropyrimidine-induced small intestinal mucosal injury.

METHODS

We performed small bowel capsule endoscopy in patients undergoing chemotherapy including fluoropyrimidine for a malignant tumor between May 2017 and June 2018 and analyzed the relationship between the endoscopic findings and diarrhea severity. We also performed a cross-sectional analysis of patient factors and routes of chemotherapy to identify risk factors of fluoropyrimidine-induced small intestinal injury.

RESULTS

Small bowel capsule endoscopy was successfully completed in 16 eligible patients. The diarrhea grade (per the Common Terminology Criteria for Adverse Events, version 4.0) was significantly correlated with the percentage of patients with a small intestinal mucosal break (grade 0, 16.7%; grade 1, 57.1%; grade 2, 100%; p = .016, Cochran-Armitage trend test). Compared to patients receiving intravenous therapy, those receiving an orally administered fluoropyrimidine had a significantly greater number of small intestinal mucosal breaks (median number of breaks [range]; intravenous 5-fluorouracil, 0 [0-13]; oral fluoropyrimidine, 6.5 [1-20]; p = .0162, Mann-Whitney U test).

CONCLUSIONS

Many patients with diarrhea caused by chemotherapy including fluoropyrimidine had small intestinal mucosal breaks. Additionally, small intestinal mucosal breaks were more severe in patients receiving a regimen of oral treatment than in those receiving a regimen of intravenous therapy. These outcomes have important implications for investigations of new strategies for preventing anti-cancer drug-induced diarrhea.

Bactericidal/Permeability-Increasing Fold-Containing Family B Member 4 May Be Associated with NSAID-Induced Enteropathy

BACKGROUND

There is considerable individual variability in nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy.

AIM

To identify the SNP that is most significantly involved with NSAID-induced enteropathy.

METHODS

One hundred fifty human subjects who were known to have a certain degree of loxoprofen- or celecoxib-induced small-intestinal damage from a previous study were enrolled. The subjects were divided into groups based on treatments and also on the increased number of small intestinal mucosal breaks. The candidate SNP was selected by an initial analysis of GWAS among the groups in various combinations. After the initial analysis, the gene including the specified SNP was analyzed in detail using GWAS and genotype imputation.

RESULTS

After analysis, 70 subjects receiving the loxoprofen treatment and 69 subjects receiving celecoxib treatment were determined to be eligible for the analysis. The minimum p value in GWAS was detected in the analysis of 16 cases with an increase of five or more mucosal breaks and 123 controls with zero to four mucosal breaks. In the GWAS, five SNPs in the bactericidal/permeability-increasing fold-containing family B member 4 (BPIFB4) gene showed the lowest p value (p = 2.69 × 10^-7 with an odds ratio of 40.9). Of the five SNPs, four were nonsynonymous SNPs (rs2070325: V268I, rs2889732: T320N, rs11699009: F527L, rs11696307: T533I, and rs11696310: intronic). Furthermore, 23 SNPs in BPIFB4 detected by genotype imputation based on the GWAS data also showed suggestive associations (p < 1 × 10^-6).

CONCLUSION

The results indicate that SNPs in BPIFB4 were associated with NSAID-induced small intestinal mucosal injury (UMIN: 000007936).

Pathophysiology of NSAID-Associated Intestinal Lesions in the Rat: Luminal Bacteria and Mucosal Inflammation as Targets for Prevention

Non-steroidal anti-inflammatory drugs (NSAIDs) can damage the small intestine, mainly through an involvement of enteric bacteria. This study examined the pathophysiology of NSAID-associated intestinal lesions in a rat model of diclofenac-enteropathy and evaluated the effect of rifaximin on small bowel damage. Enteropathy was induced in 40-week old male rats by intragastric diclofenac (4 mg/kg BID, 14 days). Rifaximin (delayed release formulation) was administered (50 mg/kg BID) 1 h before the NSAID. At the end of treatments, parameters dealing with ileal damage, inflammation, barrier integrity, microbiota composition, and TLR-NF-κB-inflammasome pathway were evaluated. In addition, the modulating effect of rifaximin on NLRP3 inflammasome was tested in an in vitro cell system. Diclofenac induced intestinal damage and inflammation, triggering an increase in tissue concentrations of tumor necrosis factor and interleukin-1β, higher expression of TLR-2 and TLR-4, MyD88, NF-κB and activation of caspase-1. In addition, the NSAID decreased ileal occludin expression and provoked a shift of bacterial phyla toward an increase in Proteobacteria and Bacteroidetes abundance. All these changes were counterbalanced by rifaximin co-administration. This drug was also capable of increasing the proportion of Lactobacilli, a genus depleted by the NSAID. In LPS-primed THP-1 cells stimulated by nigericin (a model to study the NLRP3 inflammasome), rifaximin reduced IL-1β production in a concentration-dependent fashion, this effect being associated with inhibition of the up-stream caspase-1 activation. In conclusion, diclofenac induced ileal mucosal lesions, driving inflammatory pathways and microbiota changes. In conclusion, rifaximin prevents diclofenac-induced enteropathy through both anti-bacterial and anti-inflammatory activities.

Exosomes derived from high-glucose-stimulated Schwann cells promote development of diabetic peripheral neuropathy

Schwann cells actively interact with axons of dorsal root ganglia (DRG) neurons. Exosomes mediate intercellular communication by transferring their biomaterials, including microRNAs (miRs) into recipient cells. We hypothesized that exosomes derived from Schwann cells stimulated by high glucose (HG) exosomes accelerate development of diabetic peripheral neuropathy and that exosomal cargo miRs contribute to this process. We found that HG exosomes contained high levels of miR-28, -31a, and -130a compared to exosomes derived from non-HG-stimulated Schwann cells. In vitro, treatment of distal axons with HG exosomes resulted in reduction of axonal growth, which was associated with elevation of miR-28, -31a, and -130a and reduction of their target proteins of DNA methyltransferase-3α, NUMB (an endocytic adaptor protein), synaptosome associated protein 25, and growth-associated protein-43 in axons. In vivo, administration of HG exosomes to sciatic nerves of diabetic db/db mice at 7 wk of age promoted occurrence of peripheral neuropathy characterized by impairment of nerve conduction velocity and induction of mechanic and thermal hypoesthesia, which was associated with substantial decreases in intraepidermal nerve fibers. Our findings demonstrate a functional role of exosomes derived from HG-stimulated Schwann cells in mediating development of diabetic peripheral neuropathy.-Jia, L., Chopp, M., Wang, L., Lu, X., Szalad, A., Zhang, Z. G. Exosomes derived from high-glucose-stimulated Schwann cells promote development of diabetic peripheral neuropathy.

Sex differences in NSAID-induced perturbation of human intestinal barrier function and microbiota

Intestinal barrier function and microbiota are integrally related and play critical roles in maintenance of host physiology. Sex is a key biologic variable for several disorders. Our aim was to determine sex-based differences in response to perturbation and subsequent recovery of intestinal barrier function and microbiota in healthy humans. Twenty-three volunteers underwent duodenal biopsies, mucosal impedance, and in vivo permeability measurement. Permeability testing was repeated after administration of indomethacin, then 4 to 6 wk after its discontinuation. Duodenal and fecal microbiota composition was determined using 16S rRNA amplicon sequencing. Healthy women had lower intestinal permeability and higher duodenal and fecal microbial diversity than healthy men. Intestinal permeability increases after indomethacin administration in both sexes. However, only women demonstrated decreased fecal microbial diversity, including an increase in Prevotella abundance, after indomethacin administration. Duodenal microbiota composition did not show sex-specific changes. The increase in permeability and microbiota changes normalized after discontinuation of indomethacin. In summary, women have lower intestinal permeability and higher microbial diversity. Intestinal permeability is sensitive to perturbation but recovers to baseline. Gut microbiota in women is sensitive to perturbation but appears to be more stable in men. Sex-based differences in intestinal barrier function and microbiome should be considered in future studies.-Edogawa, S., Peters, S. A., Jenkins, G. D., Gurunathan, S. V., Sundt, W. J., Johnson, S., Lennon, R. J., Dyer, R. B., Camilleri, M., Kashyap, P. C., Farrugia, G., Chen, J., Singh, R. J., Grover, M. Sex differences in NSAID-induced perturbation of human intestinal barrier function and microbiota.

Rebleeding rate and risk factors in nonsteroidal anti-inflammatory drug-induced enteropathy

OBJECTIVE

Limited evidence is available on rebleeding due to nonsteroidal anti-inflammatory drugs (NSAIDs)-induced enteropathy. Previous studies have primarily analyzed endoscopic findings. Therefore, there is a need to evaluate their clinical implications for patients. This study aimed to evaluate the rebleeding rate and its related risk factors in patients with NSAIDs-induced enteropathy.

METHODS

Of 402 patients with obscure gastrointestinal bleeding who were evaluated with capsule endoscopy, 49 were diagnosed with NSAIDs-induced enteropathy. The clinical characteristics of the patients were retrospectively analyzed. The Charlson comorbidity index was used to stratify the comorbidities. For patients who used additional drugs that influenced their tendency to bleeding, the odds ratio was calculated and used for a quantitative comparison.

RESULTS

The rebleeding rate in patients with NSAIDs-induced enteropathy was 20.4%, within a mean duration of 23.4 months. Age ≥65 years (hazard ratio [HR] 8.628, 95% confidence interval [CI] 1.152-64.625), no additional use of mucoprotective agents (HR 11.712, 95% CI 1.278-76.098) and the continuation of NSAIDs after the first bleeding episode (HR 9.861, 95% CI 1.395-98.344) were independently related to rebleeding due to NSAIDs-induced enteropathy. The underlying comorbidities, drug-related rebleeding risk scores and therapeutic use of proton pump inhibitors were not significantly different (P = 0.209, 0.212 and 0.720, respectively).

CONCLUSIONS

Approximately one-fifth of patients with NSAIDs-induced enteropathy showed rebleeding within 2 years. A careful long-term follow-up should be offered to elderly patients with NSAIDs-induced enteropathy who need continuous NSAID treatment without the additional use of mucoprotective medications.

NSAIDs and the small bowel

PURPOSE OF REVIEW

The review describes the effects of NSAID gastrointestinal toxicity on the small bowel, wherein injury is as prevalent as in the gastroduodenum. This is well documented by capsule endoscopy, which also provides an endoscopic endpoint for novel treatment strategies.

RECENT FINDINGS

Appreciation of the prevalence of NSAID enteropathy has grown with capsule endoscopy and the use of composite end points that include obscure haemoglobin decreases in clinical studies. Along with dual cyclo-oxygenase isoform inhibition, gram-negative antigen presentation plays a role in the pathogenesis of NSAID enteropathy. The concomitant use of proton pump inhibitor (PPI) agents with both selective and nonselective NSAIDs in gastroduodenal protection exacerbates endoscopic enteropathy, which is thought to be due to intestinal dysbiosis. Strategies for small bowel mucosal protection include prostaglandin repletion and augmenting the intestinal flora.

SUMMARY

NSAID- related enteropathy is common and often presents subclinically. The most common presentation is anaemia, which may be less common in those on cyclo-oxygenase (COX)-2 inhibitors than nonselective NSAIDs. PPI use worsens NSAID enteropathy with more occult bleeding and ulceration and has been linked to gram-negative intestinal dysbiosis. If NSAID cessation is not possible, COX-2 inhibition without PPI therapy should be considered in patients with upper gastrointestinal risk factors. Mucoprotective agents such as misoprostol and rebamipide show promise and probiotics may have a future role.

Metronidazole following excisional haemorrhoidectomy: a systematic review and meta-analysis

BACKGROUND

Post-operative pain is a major issue following excisional haemorrhoidectomy. Although metronidazole by both oral and topical administration routes has been shown to reduce pain after haemorrhoidectomy, its use remains a contentious issue. This systematic review and meta-analysis aims to investigate the effect of metronidazole on post-operative pain after excisional haemorrhoidectomy.

METHODS

A systematic review of the literature was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials (RCTs) published in PubMed/MEDLINE, EMBASE, CENTRAL and CINAHL, from inception to December 2016 were retrieved. The primary outcome investigated was post-operative pain reported as visual analogue score (VAS). Secondary outcomes were analgesia use, complications and time to return to normal activity. Meta-analysis was performed using Review Manager version 5.3 software.

RESULTS

Nine randomized controlled trials including 523 patients were included in the final analysis. Five studies used oral administration and four used topical. Meta-analysis showed that post-operative VAS of patients receiving metronidazole by either route was significantly less than those in comparison groups. VAS means decreased at all the time points for both oral and topical metronidazole. Topical and oral routes of administration were not compared in any study. There was no increase in complication rates and return to normal activity was significantly earlier for patients receiving metronidazole (-4.49 days; 95% confidence interval [-7.70, -1.28]; P = 0.006).

CONCLUSIONS

Both topical and oral metronidazole reduce post-operative pain without an increase in complication rates and result in an earlier return to normal activity. Further work is required to determine which the optimum route of administration is.

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.

Non-steroidal anti-inflammatory drug-induced enteropathy

Non-steroidal anti-inflammatory drugs (NSAIDs) are well known to be associated with serious upper gastrointestinal complications, such as peptic ulcer, bleeding, perforation, and obstruction. Recently, attention has been mainly focused on the small bowel injuries caused by NSAIDs, and new endoscopic techniques such as capsule endoscopy and double balloon endoscopy can help in detecting such injuries. This article reviewed the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of small bowel injuries caused by NSAIDs. Small bowel injures by NSAIDs might occur with a similar frequency and extent as those observed in the upper gastrointestinal tract. The pathogenesis of NSAID-induced enteropathy is complex and not clearly understood. The various lesions observed in the small bowel, including petechiae, reddened folds, loss of villi, erosions, and ulcers can be detected by capsule endoscopy. A drug that could prevent or treat NSAID-induced enteropathy has not yet been developed. Therefore, further investigations should be performed to elucidate the pathogenesis of such enteropathy and develop suitable preventive and treatment strategies.

Review article: a practical approach to the clinical management of NSAID enteropathy

Co-prescription of acid suppressive therapy, together with advances in small bowel imaging techniques, have shifted the burden of NSAID-related toxicity from gastro-duodenal to more distal small bowel injury. Due to predominantly subclinical disease, NSAID enteropathy remains under-recognised, with an incidence of 53-80% amongst healthy short-term users, and a prevalence of 50-71% following long-term (>3 months) use. Despite their distinct pathogenesis, those at risk of NSAID-related gastro-duodenal and small bowel complications share several risk factors. Clinical complications of NSAID enteropathy such as protein-losing enteropathy, small bowel strictures and diaphragm disease, confer significant morbidity, and are often irreversible. Small bowel prophylaxis has proven of modest efficacy after short-term, high-dose NSAID use in asymptomatic patients. While selective COX-2 inhibitors are associated with fewer gastro-duodenal complications relative to non-selective NSAIDs, their comparative benefit in protecting against small bowel enteropathy remains unclear. Prophylaxis should be considered in those at high risk of small bowel complications, as treatment options for established disease remain limited; however, the optimal agent remains unclear. We propose a clinical algorithm that may help prevent, monitor, investigate, and manage the sequelae of NSAID-induced small bowel toxicity.

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.

Bacterial translocation in critical illness

Bacterial translocation involves the passage of intestinal bacteria to extraintestinal sites and has been shown to increase morbidity and mortality in critical illness. This review outlines the pathophysiology of bacterial translocation, host defence mechanisms, and reviews the evidence for the clinical management of critically ill patients in order to minimise the negative outcomes associated with bacterial translocation.

Gut Microbiota Mediates Protection Against Enteropathy Induced by Indomethacin

Non-steroidal anti-inflammatory drugs (NSAIDs) can cause significant small bowel injuries. The role of gut microbiota in this NSAID-induced enteropathy is poorly understood. We studied the dynamic changes in gut microbiota following indomethacin administration in mice, and investigated the effects of these adaptive changes on subsequent NSAID-induced enteropathy. The changes in gut microbiota were studied using 16S rRNA sequencing, and the effects of such changes were investigated using antibiotics and a faecal transplantation model. After indomethacin treatment, significant adaptive changes in gut microbiota were observed, including increased abundance of Firmicutes and decreased abundance in that of Bacteroidetes. Depletion of gut microbiota with antibiotics led to a higher mortality (P = 0.0021) in mice compared to controls. Mice pre-transplanted with adaptively changed microbiota showed less small bowel injury and lower levels of pro-inflammatory cytokines when exposed to indomethacin. In summary, this study identifies adaptive changes in the gut microbiota upon indomethacin administration, which can in turn ameliorate further NSAID-induced injury. The heightened mortality with antibiotic depletion of the adaptively changed microbiota suggests its important role in protecting against such injury. This study provides insight for future efforts to target the microbiota as a therapeutic strategy.

Non-steroidal Anti-inflammatory Drug Induced Injury to the Small Intestine

Non-steroidal anti-inflammatory drug (NSAIDs) induced enteropathy represents an important complication of one of the most commonly used drugs worldwide. Due to previous diagnostics difficulties the real prevalence of this disease was underestimated for a long time. The pathogenesis of NSAID-enteropathy is more multifactorial and complex than formerly assumed but has still not been fully uncovered. A combination of the local and systemic effect plays an important role in pathogenesis. Thanks to novel enteroscopy methods (wireless capsule endoscopy, double balloon enteroscopy), small bowel lesions are described in a substantial section of NSAID users although most are clinically asymptomatic. The other non-invasive tests (small bowel permeability, faecal calprotectin, scintigraphy using faecal excretion of 111-indium-labelled leukocytes etc.) proposed for diagnostics are not generally used in clinical practice, mainly because of their non-specificity. Despite intensive research into possible treatment, the main measure for patients with NSAID-enteropathy is still withdrawal of NSAIDs. Double balloon enteroscopy plays an important role in the treatment of complications (bleeding, strictures).

Small bowel protection against NSAID-injury in rats: Effect of rifaximin, a poorly absorbed, GI targeted, antibiotic

Nonsteroidal anti-inflammatory drugs, besides exerting detrimental effects on the upper digestive tract, can also damage the small and large intestine. Although the underlying mechanisms remain unclear, there is evidence that enteric bacteria play a pivotal role. The present study examined the enteroprotective effects of a delayed-release formulation of rifaximin-EIR (R-EIR, 50mg/kg BID, i.g.), a poorly absorbed antibiotic with a broad spectrum of antibacterial activity, in a rat model of enteropathy induced by indomethacin (IND, 1.5mg/kg BID for 14 days) administration. R-EIR was administered starting 7 days before or in concomitance with IND administration. At the end of treatments, blood samples were collected to evaluate hemoglobin (Hb) concentration (as an index of digestive bleeding). Small intestine was processed for: (1) histological assessment of intestinal damage (percentage length of lesions over the total length examined); (2) assay of tissue myeloperoxidase (MPO) and TNF levels, as markers of inflammation; (3) assay of tissue malondialdehyde (MDA) and protein carbonyl concentrations, as an index of lipid and protein peroxidation, respectively; (4) evaluation of the major bacterial phyla. IND significantly decreased Hb levels, this effect being significantly blunted by R-EIR. IND also induced the occurrence of lesions in the jejunum and ileum. In both intestinal regions, R-EIR significantly reduced the percentage of lesions, as compared with rats receiving IND alone. Either the markers of inflammation and tissue peroxidation were significantly increased in jejunum and ileum from IND-treated rats. However, in rats treated with R-EIR, these parameters were not significantly different from those observed in controls. R-EIR was also able to counterbalance the increase in Proteobacteria and Firmicutes abundance induced by INDO. To summarize, R-EIR treatment significantly prevents IND-induced intestinal damage, this enteroprotective effect being associated with a decrease in tissue inflammation, oxidative stress and digestive bleeding as well as reversal of NSAID-induced alterations in bacterial population.

Toll-like receptor (TLR) 2 agonists ameliorate indomethacin-induced murine ileitis by suppressing the TLR4 signaling

BACKGROUND AND AIM

Few drugs have been found satisfactory in the treatment of nonsteroidal anti-inflammatory drugs (NSAIDs)-induced enteropathy. Toll-like receptor (TLR) 4 and aberrant leukocyte migration to the intestinal mucosa are reported to be involved in the pathology of intestinal enteropathy and TLR2 agonists have been found to evoke hyposensitivity to TLR4 stimulation in vitro. In this study, we investigated whether and how lipoarabinomannan (LAM) or lipoteichoic acid (LTA), TLR2 agonists, attenuated indomethacin (IND)-induced intestinal damage.

METHODS

LAM (0.5 mg/kg) or LTA (15 mg/kg) was administered intraperitoneally to mice before IND (10 mg/kg) administration. Disease activity was evaluated macroscopically and histologically. In the migration analysis, fluorescence-labeled leukocyte movement in the intestinal microvessels was observed by intravital microscopy. Expression of P-selectin, MAdCAM-1, TLR2, TLR4, and F4/80 was observed immunohistochemically. In the in vitro analysis, RAW264.7 macrophage cells were preincubated with LAM and stimulated with lipopolysaccharide (LPS), and the mRNA expression levels of TLR4, tumor necrosis factor-α, and interleukin-12p40 were measured.

RESULTS

Pretreatment with LAM or LTA significantly decreased IND-induced injury as well as decreased leukocyte infiltration. Pretreatment with LAM decreased IND-induced TLR4 expression on F4/80(+) macrophages, the level of P-selectin expression, and leukocyte migration in the small intestinal vessels. In the in vitro study, a single administration of LAM decreased TLR4 mRNA expression and inhibited the increase in mRNA expression of inflammatory cytokines by LPS in a dose-dependent manner.

CONCLUSION

TLR2 agonists attenuated IND-induced small intestinal lesions and leukocyte infiltration probably by suppressing the TLR4 signaling pathway in tissue macrophages.

Systematic review: bile acids and intestinal inflammation-luminal aggressors or regulators of mucosal defence?

BACKGROUND

Inflammatory bowel diseases (IBD), comprising Crohn's disease and ulcerative colitis (UC), are chronic conditions attributed to an aberrant immune response to luminal triggers. Recently, published work suggests a pathogenic role for bile acids in this context.

AIM

To perform a systematic review of studies investigating the role of bile acids in intestinal inflammation and present potentially relevant clinical implications.

METHODS

Pubmed search for English language articles published up to May 2015. Terms used were: 'bile', 'bile acid', 'barrier', 'small bowel injury', 'Crohn's' and 'colitis'.

RESULTS

Experimental studies support a variable role for bile acids in intestinal barrier homoeostasis. This may be attributed to different physicochemical properties, variable effects on epithelia and immune cells via bile acids-specific receptors, or through a cross-talk with the gut microbiome. A reduction in the bile acids pool, with lower concentrations of secondary forms, has been recognised for some time in Crohn's disease and associated to ileal dysfunction and bile acids malabsorption. Recent work suggests that these changes, including an increase in sulphated forms, are related to inflammatory activity in both Crohn's disease and UC. The detrimental effects of 'western diet' elements such as emulsifiers and fat, which have been implicated in the development of the current IBD and obesity epidemics, may also be bile acid-mediated.

CONCLUSIONS

Although there are only a few observational clinical studies to support an interaction, in vivo human and animal studies support an association between bile acids metabolism, the gut microbiome and intestinal inflammation. This may well prove to have significant diagnostic and therapeutic implications.

NSAID enteropathy and bacteria: a complicated relationship

The clinical significance of small intestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs) remains under-appreciated. It occurs with greater frequency than the damage caused by these drugs in the upper gastrointestinal tract, but is much more difficult to diagnose and treat. Although the pathogenesis of NSAID enteropathy remains incompletely understood, it is clear that bacteria, bile, and the enterohepatic circulation of NSAIDs are all important factors. However, they are also interrelated with one another. Bacterial enzymes can affect the cytotoxicity of bile and are essential for enterohepatic circulation of NSAIDs. Gram-negative bacteria appear to be particularly important in the pathogenesis of NSAID enteropathy, possibly through release of endotoxin. Inhibitors of gastric acid secretion significantly aggravate NSAID enteropathy, and this effect is due to significant changes in the intestinal microbiome. Treatment with antibiotics can, in some circumstances, reduce the severity of NSAID enteropathy, but published results are inconsistent. Specific antibiotic-induced changes in the microbiota have not been causally linked to prevention of intestinal damage. Treatment with probiotics, particularly Bifidobacterium, Lactobacillus, and Faecalibacteriaum prausnitzii, has shown promising effects in animal models. Our studies suggest that these beneficial effects are due to colonization by the bacteria, rather than to products released by the bacteria.

Environmental and NSAID-enteropathy: dysbiosis as a common factor

At first sight, environmental enteropathy and NSAID enteropathy may appear to have little in common. One occurs almost exclusively in poor countries and the other primarily in rich countries. One is the consequence of unhygienic living conditions, while the other is a consequence of use of a drug for relief of pain and inflammation. However, there may be a common pathogenic link between these two conditions, namely a significant alteration in the microbiome (dysbiosis), and this raises the possibility of common approaches to treatment. Correction of the dysbiosis that is central to the intestinal tissue injury and dysfunction observed in environmental and nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathies is a logical approach to bringing about restoration of intestinal function. For both conditions, removal of the trigger for dysbiosis is the simplest approach, but is not always feasible. Correcting the underlying dysbiosis through the use of probiotics or prebiotics may be a viable option.

The role of mitochondria-derived reactive oxygen species in the pathogenesis of non-steroidal anti-inflammatory drug-induced small intestinal injury

Non-steroidal anti-inflammatory drugs (NSAIDs) have been implemented in clinical settings for a long time for their anti-inflammatory effects. With the number of NSAID users increasing, gastroenterological physicians and researchers have worked hard to prevent and treat NSAID-induced gastric mucosal injury, an effort that has for the large part being successful. However, the struggle against NSAID-induced mucosal damage has taken on a new urgency due to the discovery of NSAID-induced small intestinal mucosal injury. Although the main mechanism by which NSAIDs induce small intestinal mucosal injury has been thought to depend on the inhibitory effect of NSAIDs on cyclooxygenase (COX) activity, recent studies have revealed the importance of mitochondria-derived reactive oxygen species (ROS) production, which occurs independently of COX-inhibition. ROS production is an especially important factor in the increase of small intestinal epithelial cell permeability, an early stage in the process of small intestinal mucosal injury. By clarifying the precise mechanism, together with its clinical features using novel endoscopy, effective strategies for preventing NSAID-induced small intestinal damage, especially targeting mitochondria-derived ROS production, may be developed.

Dipeptidyl peptidase IV inhibition prevents the formation and promotes the healing of indomethacin-induced intestinal ulcers in rats

BACKGROUNDS AND AIMS

We studied the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) as a possible therapy for non-steroidal anti-inflammatory drug (NSAID)-induced intestinal ulcers. Luminal nutrients release endogenous GLP-2 from enteroendocrine L cells. Since GLP-2 is degraded by dipeptidyl peptidase IV (DPPIV), we hypothesized that DPPIV inhibition combined with luminal administration of nutrients potentiates the effects of endogenous GLP-2 on intestinal injury.

METHODS

Intestinal injury was induced by indomethacin (10 mg/kg, sc) in fed rats. The long-acting DPPIV inhibitor K579 was given intragastrically (ig) or intraperitoneally (ip) before or after indomethacin treatment. L-Alanine (L-Ala) and inosine 5'-monophosphate (IMP) were co-administered ig after the treatment.

RESULTS

Indomethacin treatment induced intestinal ulcers that gradually healed after treatment. Pretreatment with ig or ip K579 given at 1 mg/kg reduced total ulcer length, whereas K579 at 3 mg/kg had no effect. Exogenous GLP-2 also reduced intestinal ulcers. The preventive effect of K579 was dose-dependently inhibited by a GLP-2 receptor antagonist. Daily treatment with K579 (1 mg/kg), GLP-2, or L-Ala + IMP after indomethacin treatment reduced total ulcer length. Co-administration (ig) of K579 and L-Ala + IMP further accelerated intestinal ulcer healing.

CONCLUSION

DPPIV inhibition and exogenous GLP-2 prevented the formation and promoted the healing of indomethacin-induced intestinal ulcers, although high-dose DPPIV inhibition reversed the preventive effect. Umami receptor agonists also enhanced the healing effects of the DPPIV inhibitor. The combination of DPPIV inhibition and luminal nutrient-induced GLP-2 release may be a useful therapeutic tool for the treatment of NSAIDs-induced intestinal ulcers.

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.

[Antiplatelet therapy with acetylsalicylic acid: approaches to reducing the frequency of gastrointenstinal adverse reactions]

Acetylsalicylic acid (ASA) is highly effective in preventing cardiovascular events, but associated with increased risk for digestive adverse reactions. The paper provides an update on the epidemiology, mechanisms, and risk factors of esophagogastroduodeno- and enteropathies during long-term low-dose ACA therapy. It outlines the key principles of their prevention.

Gastrointestinal safety of NSAIDs and over-the-counter analgesics

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used. It is well recognised that they may adversely cause damage throughout the gastrointestinal tract and aggravate pre-existing disease. Their side effects on the upper gastrointestinal tract can be assessed by various means; each study type has different clinical connotations. Short-term use (less than 14 days) demonstrates dose-dependent damage of prescribed NSAIDs; the damage is proportional to the acidity of the drugs and not seen with Cyclooxygenase-2 (COX-2) selective inhibitors that have a pKa over 7.0. There have not been any serious outcomes, such as bleeding or perforation in these studies, and Helicobacter pylori (HP) plays no role in this damage. Long-term (3 months or more) endoscopy studies in patients show ulcer rates from 15%-35% with the various NSAIDs, but serious outcomes are exceedingly rare. Epidemiological studies show an association between NSAID intake and serious events. Ibuprofen is consistently at the lower end of toxicity rankings, whereas ketorolac and azapropazone are the worst. The risk of bleeding is increased with advancing age, presence of HP, previous history of bleeding, anticoagulant use, etc. The mega-trials show that COX-2 selective agents halve the bleeding episodes, but NSAID-induced gastric bleeding is very rare usually, less than 1 in 200 subjects taking them for a year. Seventy percent of patients develop NSAID-enteropathy, which is associated with intestinal blood and protein loss and rarely strictures. Over-the-counter (OTC) use of ibuprofen and diclofenac is associated with symptomatic gastrointestinal side effects comparable with placebo. Ibuprofen is shown to be remarkably well tolerated at OTC doses in a number of studies. There are recent studies to suggest that OTC NSAIDs should be taken on a fasting stomach, not with food as commonly advocated.

The impact of non-steroidal anti-inflammatory drugs on the small intestinal epithelium

The small intestine has been called as a dark continent of digestive tract and it had been very difficult to diagnose or treat the disease of small intestine. However recent technological development including video capsule endoscopy or balloon-assisted endoscopy has made us to aware the various diseases of small intestine. By using capsule endoscopy, many researchers reported that more than 70% of patients treated continuously with non-steroidal anti-inflammatory drugs (NSAID) exhibit the mucosal damage of small intestine. In some cases, NSAID not only causes mucosal damage but also results in life threatening bleeding from small intestine, which had not been prevented or cured by gastro-protective drug or anti-gastric acid secretion drug administration. Therefore to investigate and identify the effective drug that protects small intestine from mucosal damage is urgently expected. In spite of extensive investigation in clinical field, only a few drugs such as misoprostol, a synthetic prostaglandin E₁ analogue, has been reported as an effective one but is not satisfactory enough to fulfill the requirement of patients who suffer from NSAID-induced mucosal damage of small intestine. And now, extensive study is being performed using several gastro-mucoprotective drugs by many researchers. In this review, we introduce the current clinical situation in small intestinal injury of patients under NSAID treatment, and to summarize the molecular mechanism by which NSAID, including acetyl salicylic acid, cause small intestinal damage. In addition, we present results of clinical trials performed so far, and refer the possible preventive method or treatment in the near future.

Recent Advances in NSAIDs-Induced Enteropathy Therapeutics: New Options, New Challenges

The injurious effects of NSAIDs on the small intestine were not fully appreciated until the widespread use of capsule endoscopy. It is estimated that over two-thirds of regular NSAID users develop injury in the small intestinal injuries and that these injuries are more common than gastroduodenal mucosal injuries. Recently, chronic low-dose aspirin consumption was found to be associated with injury to the lower gut and to be a significant contributing factor in small bowel ulceration, hemorrhage, and strictures. The ability of aspirin and NSAIDs to inhibit the activities of cyclooxygenase (COX) contributes to the cytotoxicity of these drugs in the gastrointestinal tract. However, many studies found that, in the small intestine, COX-independent mechanisms are the main contributors to NSAID cytotoxicity. Bile and Gram-negative bacteria are important factors in the pathogenesis of NSAID enteropathy. Here, we focus on a promising strategy to prevent NSAID-induced small intestine injury. Selective COX-2 inhibitors, prostaglandin derivatives, mucoprotective drugs, phosphatidylcholine-NSAIDs, and probiotics have potential protective effects on NSAID enteropathy.

Effectiveness of polaprezinc for low-dose aspirin-induced small-bowel mucosal injuries as evaluated by capsule endoscopy: a pilot randomized controlled study

Background

Treatment of low-dose aspirin (LDA)-induced small-bowel injury has not been established. Polaprezinc, a chelate of zinc and L-carnosine, may be efficacious for such injury. We conducted a pilot randomized controlled study to investigate whether polaprezinc is effective against LDA-induced small-bowel injuries.

Methods

Consecutive patients under long-term (>3 months) LDA treatment and who agreed to participate in our study underwent initial capsule endoscopy (CE). Patients with LDA-induced small-bowel injury apparent upon initial CE (n = 20) were randomized into a polaprezinc (150 mg/day for 4 weeks) group and a control (no polaprezinc treatment) group. All underwent follow-up CE after 4 weeks. Changes in the number and characteristics of small-bowel mucosal injuries were compared within and between the two groups.

Results

The median number of reddened lesions and erosions/ulcers upon follow-up CE in the polaprezinc group significantly decreased (P < 0.05). However, there was no significant difference in the median number of reddened lesions and erosions/ulcers upon follow-up CE in the control group.

Conclusions

Co-administration of polaprezinc may be effective against small-bowel mucosal injury associated with long-term LDA therapy.

Trial registration

UMIN Clinical Trials Registry UMIN000003687.

NSAID enteropathy: could probiotics prevent it?

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world; nevertheless, about 50-70% of patients on long-term NSAIDs develop small intestine injury, namely NSAID enteropathy, sometimes with serious outcomes. No medications with proven efficacy are yet available to prevent NSAID enteropathy. A series of therapeutic strategies targeting the different mechanisms involved in small bowel injury have been investigated, but without definitive results. Intestinal bacteria and their degradation products are essential for the development of NSAID-induced small bowel lesions, because "germ-free" animals were found to be resistant to indomethacin injuries. Therefore, it has been suggested that modulating the intestinal flora, for example by using probiotics, could protect against NSAID enteropathy. In this work, we reviewed the main therapeutic strategies for NSAID enteropathy, in particular analyzing the available studies relating to the eventual protective role of probiotics. We found that results are not all concordant; nevertheless, the more recent studies provide better understanding about pathogenetic mechanisms involved in small intestinal injury and the role of probiotics, and show encouraging results. Larger and well-designed studies should be performed to evaluate the actual role of probiotics in NSAID enteropathy, the eventual differences among probiotic strains, dose-responses, and optimal duration of therapy.