Small intestinal injury caused by NSAIDs/aspirin: finding new from old

The influence of different proton pump inhibitors and potassium-competitive acid blockers on indomethacin-induced small intestinal injury

BACKGROUND AND AIM

The influence of gastric acid inhibitors (GAIs) on nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy is controversial. Herein, the influences of different GAIs on NSAID-induced intestinal injury and the underlying mechanisms are clarified.

METHODS

Indomethacin (IND; 10 mg/kg/day) was administered to mice to induce small intestinal injury. Disease activity was examined macroscopically and histologically. The permeability of small intestine was evaluated by measuring plasma lipopolysaccharide levels. 16S rDNA sequencing was performed to determine the composition of intestinal flora.

RESULTS

Among the four GAIs, ilaprazole (IPZ) significantly attenuated IND-induced small intestinal injury and maintained the integrity of the mucosal barrier. Omeprazole (OPZ) and vonoprazan (VPZ) ameliorated ulceration without significant differences, while rabeprazole (RPZ) failed to protect against the injury. To explore the potential mechanism, we investigated changes in the gut microbiota mediated by GAIs. After 5-day administration, GAIs significantly altered the composition of the gut microbiota. The IND group had a significant decrease in alpha diversity compared with the control group, and this decrease was reversed by OPZ and IPZ treatment, respectively. After IPZ treatment, the community membership was more assembled in the control group than the IND group. Further, we found that Lactobacillus was significantly increased in the groups of OPZ, IPZ, and VPZ, while Bacteroides was significantly increased in the RPZ group.

CONCLUSION

Our results indicated that GAIs have different influences on the mucosal barrier, possibly by altering the composition of intestinal microbiota, and the impacts mediated by various GAIs in the IND-induced intestinal damage model seem different.

Clinical features of obscure gastrointestinal bleeding undergoing capsule endoscopy: A retrospective cohort study

Background

Capsule endoscopy has been widely used to investigate obscure gastrointestinal bleeding (OGIB) in the small intestine since its approval in 2001. However, the clinical features of OGIB remain unclear.

Aim

We retrospectively examined the clinical features and risk factors of OGIB in patients who underwent capsule endoscopy in our hospital.

Methods

We included 420 of the 431 patients who underwent capsule endoscopy from June 2014 to May 2021, in whom the small intestine could be observed. We retrospectively compared the clinical features and treatment of OGIB cases, with or without active small bowel bleeding (n = 173), with other cases (n = 247). Patient sex, age, diabetes mellitus, and heart failure histories were matched for the analysis.

Results

The male/female ratio was 247/173 and the average age was 51.54 years. In multivariate analysis, the use of direct oral anticoagulants was significant (P = 0.016), and vascular lesions (P = 0.018) were observed in OGIB cases. When OGIB cases with and without active small bowel bleeding were compared, serum albumin level was lower in cases with active bleeding (P = 0.031). When treatment of OGIB cases were compared, those without vascular lesions could be treated conservatively (P = 0.0047). In the 1:1 propensity score matching analysis, serum creatinine level was elevated in cases of active bleeding (P = 0.029), and cases without vascular lesions were treated conservatively (P = 0.010).

Conclusions

Use of direct oral anticoagulants is frequently associated with OGIB. OGIB patients without vascular lesions may be treated conservatively.

Protective role of resolvin D1, a pro-resolving lipid mediator, in nonsteroidal anti-inflammatory drug-induced small intestinal damage

Resolvin D1, a specialized pro-resolving lipid mediator produced from docosahexaenoic acid by 15- and 5-lipoxygenase, exerts anti-inflammatory effects driving to the resolution of inflammation. The present study aimed to elucidate its role in small intestinal damage induced by nonsteroidal anti-inflammatory drug (NSAID). Indomethacin was administered orally to C57BL/6J male mice, which were sacrificed 24 h later to collect small intestine specimens. Before administration of indomethacin, mice were subjected to intraperitoneal treatment with resolvin D1 or oral administration of baicalein, a 15-lipoxygenase inhibitor. Small intestinal damage induced by indomethacin was attenuated by pretreatment with resolvin D1. Furthermore, resolvin D1 reduced the gene expression levels of interleukin-1β, tumor necrosis factor-α, and CXCL1/keratinocyte chemoattractant. Conversely, the inhibition of 15-lipoxygenase activity by baicalein increased the expression of genes coding for these inflammatory cytokines and chemokine, leading to exacerbated small intestinal damage, and reduced the concentration of resolvin D1 in the small intestinal tissue. Exogenous treatment with resolvin D1 negated the deleterious effect of baicalein. 15-lipoxygenase was mainly expressed in the epithelium and inflammatory cells of the small intestine, and its gene and protein expression was not affected by the administration of indomethacin. Inhibition of the resolvin D1 receptor, lipoxin A4 receptor /formyl peptide receptor 2, by its specific inhibitors Boc-1 and WRW4 aggravated indomethacin-induced small intestinal damage. Collectively, these results indicate that resolvin D1 produced by 15-lipoxygenase contributes to mucoprotection against NSAID-induced small intestinal damage through its anti-inflammatory effect.

Protective effects of orally administered shark compound peptides from Chiloscyllium plagiosum against acute inflammation

The anti-inflammatory effects of shark compound peptides (SCP) from Chiloscyllium plagiosum were investigated. Results showed that SCP enhanced the viability of RAW 264.7 macrophages in vitro in a dose-dependent manner. Orally administered SCP exhibited potent anti-inflammatory activity in lipopolysaccharide (LPS)-challenged mice by suppressing serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), as well as nitric oxide (NO). Moreover, SCP significantly inhibited the inflammatory rise of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and creatinine (CRE), while blocking the decline of cholinesterase (CHE), with an efficacy close to aspirin. This research showed that orally administered SCP from C. plagiosum notably downregulated uncontrolled inflammatory responses, and conferred substantial protection from endotoxin-induced acute hepatic damage and renal functional impairment. Therefore, oral supplementation of SCP can be used as a preventive approach to reduce the risk of inflammatory-related diseases.

The protective effect of Bifidobacterium bifidum G9-1 against mucus degradation by Akkermansia muciniphila following small intestine injury caused by a proton pump inhibitor and aspirin

Proton pump inhibitors (PPIs) can alleviate upper gastrointestinal injury but paradoxically exacerbate aspirin (ASA)-induced small intestine injury. In this study, our goal was to simulate this exacerbation by developing an appropriate animal model, which may help in establishing treatments. Methods: Male mice were fed a 60% fructose diet for 9 weeks, then administered 200 mg/kg ASA 3 h before sacrifice. The PPI omeprazole was administered intraperitoneally once daily for 9 weeks. Bifidobacterium bifidum G9-1 was administered orally for the last week. In addition, Akkermansia muciniphila was administered orally for 9 weeks instead of omeprazole. Results: ASA-induced small-intestine injury was observed in high-fructose fed mice. Omeprazole exacerbated ASA-induced intestinal damage, significantly decreased Bifidobacteria levels, and significantly increased A. muciniphila counts in the jejunum. The direct administration of A. muciniphila caused thinning of the jejunum mucus layer, which was also observed in mice that received ASA and omeprazole. On the other hand, the administration of Bifidobacterium bifidum G9-1 inhibited A. muciniphila growth and reduced thinning of the mucus layer. The number of goblet cells in the jejunum was reduced by the administration of ASA and omeprazole, while Bifidobacterium bifidum G9-1 prevented the reduction. Conclusions: These results suggest that omeprazole-induced gut dysbiosis promotes Akkermansia growth and inhibits Bifidobacterium growth, leading to a thinning of the mucus layer through a reduction in goblet cells in the small intestine. Probiotics are, therefore, a promising approach for the treatment of small intestine 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.

Study on the characteristic of intestinal flora in patients with dual antiplatelet therapy

Objective: The objective of the study was to explore the intestinal flora in patients with dual antiplatelet therapy.Method: We collected fresh stool specimens from 10 patients receiving dual antiplatelet therapy and 10 healthy people as control group. Then, we extracted faecal DNA, amplified 16 s rNDA V3-V4 area, and applied Illumina Miseq to analyse the structure of intestinal flora.Result: At class level, DAPT group show higher abundance of class Bacilli and lower abundance of class Erysipelotrichia. At order level, the abundance of order Lactobacillales in DAPT group is higher (p < .05), while the abundance of order Erysipelotrichales is lower in DAPT group (p < .05). At family level, the abundance of family Streptococcaceae and family Lactobacillaceae in DAPT group is higher (p < .05), while the abundance of family Acidaminococcaceae and family Erysipelotrichaceae is lower in DAPT group (p < .05). At genus level, the abundance of genus Streptococcus and genus Klebsiella in DAPT group is higher (p < .05), while the abundance of genus Blautia, genus Phascolarctobacterium and genus Megamonas is lower in DAPT group (p < .05).Conclusion: Taking aspirin and clopidogrel will not cause a change in the biodiversity of intestinal flora. There are significant differences in the intestinal flora of DAPT group compared with the control group at class, order, family and genus level.

Investigation of small intestinal lesions in dialysis patients using capsule endoscopy

INTRODUCTION

Although gastrointestinal hemorrhage is an important complication for dialysis patients, the details of many points remain unclear with regard to small intestinal lesions.

METHODS

Capsule endoscopy was performed in fecal occult blood-positive dialysis (n =16) and non-dialysis (n = 20) patients after upper and lower gastrointestinal endoscopies failed to reveal hemorrhagic lesions.

FINDINGS

Erosive lesions were observed in 50.0% (8/16) and 25.0% (5/20) of the dialysis and non-dialysis groups, respectively. Vascular lesions were observed in 62.5% (10/16) and 25.0% (5/20), respectively. Vascular lesions were observed at a significantly higher rate in the dialysis patients (P = 0.041), but no significant difference was noted in erosive lesions (P = 0.188). Of patients taking proton pump inhibitor (PPI), Non-Steroidal Anti-Inflammatory Drugs, and antiplatelet drugs, only oral PPI administration was associated with vascular lesions (P = 0.02).

DISCUSSION

In dialysis patients, vascular lesions are the most common among small intestinal lesions, suggesting that they may have caused previously unexplained gastrointestinal hemorrhage in dialysis patients. It was also suggested that the frequent use of PPI may be a cause of small intestinal lesions.

Disruption of female reproductive function by endotoxins

Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia, and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.

Down-regulation of hepatic CYP3A1 expression in a rat model of indomethacin-induced small intestinal ulcers

The liver and the small intestine are closely related in the processes of drug absorption, metabolism and excretion via the enterohepatic circulation. Small intestinal ulcers are a serious adverse effect commonly occurring in patients taking nonsteroidal anti-inflammatory drugs. However, the influence of small intestinal ulcers on drug metabolism has not been established. This study examined the expressional changes of cytochrome P450 (CYP) in the liver using an indomethacin-induced small intestinal ulcer rat model and in cultured cells. After the administration of indomethacin to rats, ulcers were observed in the small intestine and expression of CYP3A1, the major isoform of hepatic CYP, was significantly down-regulated in the liver, accompanied by increased expression of inducible nitric oxide synthase, tumor necrosis factor α, interleukin (IL)-1β and IL-6, in the small intestine and the liver. The indomethacin-induced small intestinal ulceration, the increase in inflammatory mediators in the small intestine and the liver, and the down-regulation of CYP3A1 expression in the liver were inhibited by co-administration of ampicillin, an antibacterial agent. In the human hepatic HepG2 cell line, IL-1β, IL-6 and NOC-18, an NO donor, caused down-regulation of CYP3A4, the major isoform of human CYP3A. Thus, this study suggests that after indomethacin treatment small intestinal ulcers cause the down-regulation of CYP3A1 in the rat liver through an increase in ulcer-derived inflammatory mediators. Copyright © 2016 John Wiley & Sons, Ltd.

Clinical importance of nonsteroidal anti-inflammatory drug enteropathy: the relevance of tumor necrosis factor as a promising target

The pathogenesis of nonsteroidal anti-inflammatory drug (NSAID) enteropathy is still unclear, and consequently, there is no approved therapeutic strategy for ameliorating such damage. On the other hand, molecular treatment strategies targeting tumor necrosis factor (TNF) exerts beneficial effects on NSAID-induced intestinal lesions in rodents and rheumatoid arthritis patients. Thus, TNF appears to be a potential therapeutic target for both the prevention and treatment of NSAID enteropathy. However, the causative relationship between TNF and NSAID enteropathy is largely unknown. Currently approved anti-TNF agents are highly expensive and exhibit numerous side effects. Hence, in this review, the pivotal role of TNF in NSAID enteropathy has been summarized and plant-derived polyphenols have been suggested as useful alternative anti-TNF agents because of their ability to suppress TNF activated inflammatory pathways both in vitro and in vivo.

A multicenter, randomized, double-blind, placebo-controlled trial of high-dose rebamipide treatment for low-dose aspirin-induced moderate-to-severe small intestinal damage

BACKGROUND

Low-dose aspirin (LDA) frequently causes small bowel injury. While some drugs have been reported to be effective in treating LDA-induced small intestinal damage, most studies did not exclude patients with mild damage thought to be clinically insignificant.

AIM

We conducted a multicenter, randomized, double-blind, placebo-controlled trial to assess the efficacy of a high dose of rebamipide, a gastroprotective drug, for LDA-induced moderate-to-severe enteropathy.

METHODS

We enrolled patients who received 100 mg of enteric-coated aspirin daily for more than 3 months and were found to have more than 3 mucosal breaks (i.e., erosions or ulcers) in the small intestine by capsule endoscopy. Eligible patients were assigned to receive either rebamipide 300 mg (triple dose) 3 times daily or placebo for 8 weeks in a 2:1 ratio. Capsule endoscopy was then repeated. The primary endpoint was the change in the number of mucosal breaks from baseline to 8 weeks. Secondary endpoints included the complete healing of mucosal breaks at 8 weeks and the change in Lewis score (an endoscopic score assessing damage severity) from baseline to 8 weeks.

RESULTS

The study was completed by 38 patients (rebamipide group: n = 25, placebo group: n = 13). After 8 weeks of treatment, rebamipide, but not placebo, significantly decreased the number of mucosal breaks (p = 0.046). While the difference was not significant (p = 0.13), the rate of complete mucosal break healing in the rebamipide group (32%, 8 of 25) tended to be higher than that in the placebo group (7.7%, 1 of 13). Rebamipide treatment significantly improved intestinal damage severity as assessed by the Lewis score (p = 0.02), whereas placebo did not. The triple dose of rebamipide was well tolerated.

CONCLUSIONS

High-dose rebamipide is effective for the treatment of LDA-induced moderate-to-severe enteropathy.

TRIAL REGISTRATION

UMIN Clinical Trials Registry UMIN000003463.

Nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and gastrointestinal injury: contrasting interactions in the stomach and small intestine

Nonsteroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs) are among the most frequently prescribed groups of drugs worldwide. The use of NSAIDs is associated with a high number of significant adverse effects. Recently, the safety of PPIs has also been challenged. Capsule endoscopy studies reveal that even low-dose NSAIDs are responsible for gut mucosal injury and numerous clinical adverse effects, for example, bleeding and anemia, that might be difficult to diagnose. The frequent use of PPIs can exacerbate NSAID-induced small intestinal injury by altering intestinal microbiota. Thus, the use of PPI is considered to be an independent risk factor associated with NSAID-associated enteropathy. In this review, we discuss this important clinical problem and review relevant aspects of epidemiology, pathophysiology, and management. We also present the hypothesis that even minor and subclinical injury to the intestinal mucosa can result in significant, though delayed, metabolic consequences, which may seriously affect the health of an individual. PubMed was searched using the following key words (each key word alone and in combination): gut microbiota, microbiome, non-steroidal anti inflammatory drugs, proton pump inhibitors, enteropathy, probiotic, antibiotic, mucosal injury, enteroscopy, and capsule endoscopy. Google engine search was also carried out to identify additional relevant articles. Both original and review articles published in English were reviewed.

New evidence on the impact of antithrombotics in patients submitted to small bowel capsule endoscopy for the evaluation of obscure gastrointestinal bleeding

Objectives. Small bowel capsule endoscopy (SBCE) plays a decisive role in the obscure gastrointestinal bleeding (OGIB) diagnosis. Antithrombotics may increase bleeding risk in patients with preexistent lesions or through direct mucosal aggression. We aimed to correlate antithrombotics usage with lesions with bleeding potential found in SBCE. Methods. Retrospective single-center study including 274 consecutive SBCE performed over 7 years for OGIB. The lesions were classified as P0 (no bleeding potential), P1 (uncertain bleeding potential: erosions), and P2 (high bleeding potential: angioectasias, ulcers, and tumors). We assessed antiplatelet and anticoagulant drug use during the 60 days preceding SBCE. Results. One-third of the patients were under antithrombotic therapy. The diagnostic yield of SBCE for P2 lesions was 30.0%. Angioectasias (20.4%) were the most frequently observed lesions. There was a significant correlation between anticoagulant drug use and a higher incidence of P2 lesions in the small bowel (43.2% versus 26.5%; OR = 2.11, P = 0.026). We found no significant correlation between antiplatelets and lesions with bleeding potential in SBCE. Conclusions. Small bowel lesions with high bleeding potential were more frequently detected when the patient was on anticoagulant drugs, resulting in a twofold risk. Antiplatelet drugs were not associated with small bowel lesions.

Role of transient receptor potential vanilloid 4 activation in indomethacin-induced intestinal damage

Gastrointestinal ulcers and bleeding are serious complications of nonsteroidal anti-inflammatory drug (NSAID) use. Although administration of antibiotics and Toll-like receptor 4 knockdown mitigate NSAID-induced enteropathy, the molecular mechanism of these effects is poorly understood. Intestinal hyperpermeability is speculated to trigger the initial damage due to NSAID use. Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel expressed throughout the gastrointestinal tract epithelium that is activated by temperature, extension, and chemicals such as 5,6-epoxyeicosatrienoic acid (5,6-EET). The aim of this study was to investigate the possible role of TRPV4 in NSAID-induced intestinal damage. TRPV4 mRNA and protein expression was confirmed by RT-PCR and immunochemistry, respectively, in mouse and human tissues while TRPV4 channel activity of the intestinal cell line IEC-6 was assessed by Ca(2+)-imaging analysis. TRPV4 activators or the NSAID indomethacin significantly decreased transepithelial resistance (TER) in IEC-6 cells, and indomethacin-induced TER decreases were inhibited by specific TRPV4 inhibitors or small-interfering RNA TRPV4 knockdown, as well as by the epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide, which decreased 5,6-EET levels. In TRPV4 knockout mice, indomethacin-induced intestinal damage was significantly reduced compared with WT mice. Taken together, these results show that TRPV4 activation in the intestinal epithelium caused epithelial hyperpermeability in response to NSAID-induced arachidonic acid metabolites and contributed to NSAID-induced intestinal damage. Thus, TRPV4 could be a promising new therapeutic target for the prevention of NSAID-induced intestinal damage.

Anti-tumour necrosis factor agents reduce non-steroidal anti-inflammatory drug-induced small bowel injury in rheumatoid arthritis patients

OBJECTIVE

The role of tumour necrosis factor α (TNFα) in the pathogenesis of non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal damage remains unclear. We evaluated the preventive effect of anti-TNF therapy against NSAID-induced enteropathy in rheumatoid arthritis (RA) patients.

DESIGN

Capsule endoscopy was performed in 95 consecutive RA patients who received NSAID for more than 3 months, with or without anti-TNF therapy over a period of 3 months. The findings were scored from 0 to 4: 0, normal; 1, red spots; 2, one to four erosions; 3, more than four erosions; and 4, large erosions/ulcers. The relationship between the use of anti-TNF therapy and the risk of severe damage (scores 3 or 4) or the most severe damage (score 4) was assessed using multiple logistic regression analysis. Furthermore, a propensity score matching analysis was performed to reduce the effects of TNF selection bias.

RESULTS

By stratifying the patients on the basis of anti-TNF therapy, we obtained crude OR of 0.23 for severe damage (95% CI 0.09 to 0.65) and 0.37 for the most severe damage (95% CI 0.16 to 0.86). This protective effect of anti-TNF therapy remained robust to adjustments for baseline characteristics, with the adjusted OR for severe damage and the most severe damage ranging from 0.23 to 0.26 and 0.06 to 0.41, respectively. Propensity score matching yielded similar results and showed the protective effects of anti-TNF therapy against severe and most severe damage.

CONCLUSIONS

Anti-TNF therapy may protect against NSAID-induced small intestinal damage in RA patients.

Role of small intestinal bacterial overgrowth in severe small intestinal damage in chronic non-steroidal anti-inflammatory drug users

OBJECTIVE. Enteric bacteria play a significant role in the pathogenesis of non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal damage. However, the association between small intestinal bacterial overgrowth (SIBO) and NSAID-induced small intestinal damage remains unclear. The aim of the study was to examine the association between SIBO and the presence of NSAID-induced severe small intestinal damage or its symptoms in chronic NSAID users. MATERIALS AND METHODS. Forty-three patients who had been using NSAIDs for over 3 months were enrolled. They were examined by capsule endoscopy and a lactulose hydrogen breath test (LHBT). We defined severe small intestinal damage as the presence of more than four small erosions or large erosions/ulcers. The LHBT result was considered positive if there was an increase in the level of breath hydrogen gas of >20 ppm above baseline. RESULTS. Out of 43 patients, 22 (51%) had severe small intestinal damage. The LHBT was positive in 5 of 21 patients (24%) without severe small intestinal damage and in 13 of 21 patients (59%) with severe small intestinal damage. Multiple logistic regression analysis showed that an LHBT-positive result was significantly associated with increased odds ratio for severe small intestinal damage (OR, 6.54; 95% CI, 1.40-30.50). There was no significant difference in the presence of symptoms between the LHBT-positive and LHBT-negative patients with severe small intestinal damage. CONCLUSION. SIBO might have a role in the development of severe small intestinal damage in chronic NSAID users.

[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.

Intestinal and hepatic expression of cytochrome P450s and mdr1a in rats with indomethacin-induced small intestinal ulcers

BACKGROUND

Non-steroidal anti-inflammatory drugs induce the serious side effect of small intestinal ulcerations (SIUs), but little information is available regarding the consequences to drug metabolism and absorption.

AIM

We examined the existence of secondary hepatic inflammation in rats with indomethacin (INM)-induced SIUs and assessed its relationship to the cytochrome P450 (CYP) and P-glycoprotein (mdr1a), the major drug-metabolizing factors in the small intestine and the liver.

METHODS

Gene expression of the CYP family of enzymes and mdr1a was measured with quantitative real-time polymerase chain reaction (qPCR). Vancomycin (VCM), a poorly absorbed drug, was administered intraduodenally to rats with SIUs.

RESULTS

INM induced SIUs predominantly in the lower region of the small intestine with high expression of inflammatory markers. Liver dysfunction was also observed, which suggested a secondary inflammatory response in rats with SIUs. In the liver of rats with SIUs, the expression of CYP2C11, CYP2E1, and CYP3A1 was significantly decreased, and loss of CYP3A protein was observed. Although previous studies have shown a direct effect of INM on CYP3A activity, we could not confirm any change in hepatic CY3A4 expression (major isoform of human CYP3A) in vitro. The plasma VCM concentration was increased in rats with SIUs due to partial absorption from the mucosal injury, but not in normal mucosa.

CONCLUSIONS

INM-induced SIUs had a subtle effect on intestinal CYP expression, but had an apparent action on hepatic CYP, which was influenced, at least in part, by the secondary inflammation. Furthermore, drug absorption was increased in rats with SIUs.

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.

Effector and memory T cell responses to commensal bacteria

Barrier surfaces are home to a vast population of commensal organisms that together encode millions of proteins; each of them possessing several potential foreign antigens. Regulation of immune responses to this enormous antigenic load represents a tremendous challenge for the immune system. Tissues exposed to commensals have developed elaborate systems of regulation including specialized populations of resident lymphocytes that maintain barrier function and limit potential responses to commensal antigens. However, in settings of infection and inflammation these regulatory mechanisms are compromised and specific effector responses against commensal bacteria can develop. This review discusses the circumstances controlling the fate of commensal specific T cells and how dysregulation of these responses could lead to severe pathological outcomes.

Design, synthesis and biological evaluation of enzymatically cleavable NSAIDs prodrugs derived from self-immolative dendritic scaffolds for the treatment of inflammatory diseases

It has been reported that delivery systems based on dendritic prodrugs of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) improved the properties of drug molecules and reduced the side effects and irritation on the gastric mucosa. To find a more effective way in NSAIDs dendritic prodrugs, in this paper, three different dendritic scaffolds of enzymatically cleavable naproxen conjugates have been synthesized in a convergent approach and well characterized by NMR and MS techniques. These self-immolative dendritic NISADs prodrugs programmed to release multiple molecules of the potent naproxen after a single enzymatic activation step, and in 50% human plasma, the drug released from the compound T3 reaching 47.3% after 24h in vitro assay. Moreover, all prodrugs were also found to maintain more significant anti-inflammatory activity, no significant cytotoxicity against HEK293 cells and less degree of ulcerogenic potential in vivo than their monomeric counterpart naproxen. These results provided an effective entry to the development of new dendritic NSAIDs prodrugs.