The pathogenesis and consequence of non steroidal anti-inflammatory drug induced small intestinal inflammation in man

Statement on Best Practices in the Use of Pathology as a Diagnostic Tool for Celiac Disease: A Guide for Clinicians and Pathologists

Small intestinal biopsy interpretation has been the cornerstone for the diagnosis of celiac disease for over 50 years. Despite the existence of sensitive and specific serological tests, duodenal mucosal biopsies continue to be obtained in the vast majority of patients in whom a diagnosis of celiac disease is being considered. The accurate evaluation of these biopsies requires coordination and information sharing between the gastroenterologist, laboratory, and pathologist in order to optimize tissue sampling, preparation and interpretation. This document, a collaboration between the Rodger C. Haggitt Gastrointestinal Pathology Society and the North American Association for the Study of Celiac Disease, is intended to provide clinicians and pathologists with a summary of best practices in the use of endoscopy and biopsy for patients with suspected celiac disease. The authors present a comprehensive and critical appraisal of the literature with respect to the topics of endoscopic findings, best methods for the obtaining biopsies, completing the pathology form and pathologic assessment, including evaluating intraepithelial lymphocytes and villous architecture. A discussion of conditions with overlapping pathologic findings in duodenal mucosal biopsies is presented. In order to provide additional guidance for challenging situations, the authors include an appendix containing practical suggestions. This review may be utilized in interdisciplinary discussions to optimize care for patients with possible celiac disease.

Severe enteropathy with villous atrophy in prolonged mefenamic acid users - a currently under-recognized in previously well-recognized complication: Case report and review of literature

RATIONALE

Mefenamic acid-induced enteropathy may be an under-recognized condition because few reported cases and no review of literature to comprehensively describe all reported cases exist. From inception until February 2017, a systematic literature search identified twenty original reports of cases of mefenamic acid-induced enteropathy. Additional five cases were identified at our hospital. All cases were included in the analyses.

PATIENT CONCERNS

Most patients had been regularly taking therapeutic dosages of mefenamic acid for at least three months before symptoms developed. All patients presented with chronic diarrhea with significant weight loss. Approximately one-third of the cases had some degree of anemia and hypoalbuminemia.

DIAGNOSES

Endoscopic findings could range from very mild abnormalities, such as mild atrophic mucosa, to marked abnormalities, such as blunted villi with scalloping appearance in the small intestine and inflamed mucosa with a few superficial ulcers in the ileum and colon. Pathological findings included flattened small intestinal villi and mixed inflammatory infiltrates including eosinophils in lamina propria.

INTERVENTION

After identifying history of prolong mefenamic acid exposure, all patients were prescribed to stop this medication. Nutritional support and substitutional treatment for mefenamic acid were provided as well.

OUTCOMES

All symptoms responded dramatically to drug withdrawal. Some patients could change to use other nonsteroidal anti-inflammatory drugs (NSAIDs) without symptoms reoccurring.

LESSONS

Unlike other traditional NSAIDs, mefenamic acid could induce intestinal villous atrophy. An adequate drug history is crucial to identifying the condition. Protracted diarrhea occurring during treatment should be the indication to cease the medicine promptly.

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).

Toward More GI-Friendly Anti-Inflammatory Medications

OPINION STATEMENT

Despite the introduction 20-30 years ago of potent inhibitors of gastric acid secretion and anti-inflammatory drugs that preferentially inhibit cyclo-oxygenase (COX)-2, the GI adverse effects of nonsteroidal anti-inflammatory drugs (NSAIDs) remain a significant clinical concern and a considerable economic burden. Inhibitors of acid secretion and selective COX-2 inhibitors reduce damage only in the proximal GI tract (stomach and proximal duodenum), but NSAIDs produce injury and bleeding throughout the GI tract. The small intestinal damage caused by NSAIDs is common, difficult to diagnose, and there are no proven-effective preventative or curative therapies. There is also emerging evidence that proton pump inhibitors (PPIs) and histamine H2-receptor antagonists (H2RAs) exacerbate NSAID-induced small intestinal injury. A new approach to solve this clinical problem is to deliver an endogenous, cytoprotective "rescue molecule" together with a COX inhibitor. Hydrogen sulfide (H2S) is a naturally produced, potent protective agent in the GI tract. H2S-releasing NSAIDs have been synthesized and extensively tested in laboratory animals and humans. They exhibit improved anti-inflammatory activity over the parent NSAID, while causing negligible damage in the GI tract.

Polypharmacy of osteoarthritis: the perfect intestinal storm

Osteoarthritis is an increasingly prevalent disorder with an incidence rate that rises sharply with age. Unfortunately, the most commonly used medications for providing symptomatic relief, nonsteroidal anti-inflammatory drugs (NSAIDs), can cause significant gastrointestinal (GI) ulceration. There is recent evidence that agents commonly employed to protect the upper GI tract actually increase the incidence and severity of ulceration and bleeding in the lower intestine. Intestinal injury is more difficult to diagnose and treat than upper GI damage, and symptoms correlate poorly with the severity of tissue injury. Moreover, use of low-dose aspirin for cardioprotection (a common co-treatment with the selective cyclooxygenase-2 inhibitors) further augments intestinal damage, particularly when enteric-coated aspirin is used. Thus, by focusing entirely on prevention of NSAID-induced damage to the upper GI tract, physicians may be inadvertently placing their patients at risk of serious, difficult-to-diagnose injury for which there are no proven-effective therapies and are associated with significantly higher rates of morbidity and mortality.

Skimmed, sterilized, and concentrated bovine late colostrum promotes both prevention and recovery from intestinal tissue damage in mice

Bovine colostrum is a rich source of tissue repair and growth factors, and inhibits gastrointestinal injury induced by the side effects of nonsteroidal antiinflammatory drugs (NSAID), such as indomethacin. Nonsteroidal antiinflammatory drugs are drugs with analgesic and antipyretic effects, but in higher doses they have inflammatory effects. The pathogenesis of small intestinal damage caused by NSAID is unclear. The present study was performed to investigate the antiinflammatory effects of skimmed, sterilized, and concentrated bovine late colostrum on intestinal injury induced by side effects of NSAID, and then to identify the active ingredient in the colostrum for intestinal tissue. In Japan, the sale of bovine colostrum within 5 d after parturition is prohibited by law. Therefore, we focused on bovine late colostrum obtained from healthy lactating cows 6 to 7 d after parturition. Proliferation of small intestine epithelial cells was stimulated in mice fed the colostrum for 1 wk. With regard to indomethacin-induced enteropathy, both prefeeding and postfeeding with colostrum facilitated growth of the intestinal villi, indicating preventive and healing effects. Furthermore, to identify the active ingredient in the colostrum responsible for this effect, the casein and whey fractions were prepared from the colostrum and fed to normal mice. Only the colostrum casein fraction stimulated intestinal villus elongation, whereas the whey fraction and mature milk casein showed no such effect. Taken together, these observations indicate that the skimmed, sterilized, and concentrated bovine late colostrum, especially the casein fraction, could be used to treat the injurious effects of NSAID in the intestine and could be effective for treatment of other ulcerative conditions in the bowel, suggesting that the colostrum has therapeutic potential for intestinal inflammation.

Nonsteroidal antiinflammatory drugs and cyclooxygenase inhibition in the gastrointestinal tract: a trip from peptic ulcer to colon cancer

Aspirin was commercialized more than a 100 years ago. Today, this compound is still widely prescribed, and new mechanisms of action and indications are being tested. Inhibition of cyclooxygenase (COX)-1 and COX-2 by aspirin or its related compounds, nonsteroidal antiinflammatory drugs (NSAIDs), has been associated with both adverse and beneficial effects in the gastrointestinal (GI) tract. Inhibition of COX-1 has been linked to GI adverse effects. Adverse effects of NSAIDs and aspirin in the upper GI tract include esophagitis, peptic ulcer, peptic ulcer complications, and death. Effective preventive therapies are available that have been associated with a progressive decline in the rate of hospitalization due to upper GI complications. NSAIDs and aspirin can also damage the small bowel and the colon. NSAID enteropathy is frequent and in most cases subclinical (increased mucosal permeability, inflammation, erosion, ulcer). However, more serious clinical outcomes such as anemia, bleeding, perforation, obstruction, diverticulitis, and deaths have also been described. Prevention therapy of NSAID damage to the lower GI tract is not well defined. Inhibition of COX-2 by NSAIDs, coxibs, or aspirin seems to provide beneficial effects to the GI tract. Observational studies show that these compounds reduce the risk of both upper and lower GI cancers. Randomized controlled trials have shown that aspirin and coxibs reduce the recurrence rate of colonic polyps, and long-term cohort studies have shown that aspirin reduces the risk of colon cancer time and dose dependently. New studies will have to define the appropriate population that may benefit with these therapies.

Nonsteroidal anti-inflammatory drugs and lower gastrointestinal complications

In addition to the upper GI tract, NSAIDs can damage the small bowel and the colon. NSAID enteropathy is frequent and may be present in more than 60% of patients taking these drugs long term. In most cases, damage is subclinical, including increased mucosal permeability, inflammation, erosions, ulceration, but other more serious clinical outcomes such as anemia, and overall bleeding, perforation, obstruction, diverticulitis and deaths have also been described. The magnitude of these serious outcomes from the lower GI tract is not well defined, but recent data suggest that they may be as frequent and severe as upper GI complications. Contrary to what happens in the upper GI tract, treatment and prevention of NSAID enteropathy is difficult, since the pathogenic mechanisms are different and not well understood. Among other options, misoprostol, antibiotics, and sulphasalazine have been proved to be effective in animal models, but they have not been properly tested in humans. Selective COX-2 inhibition is emerging as a potential alternative to tNSAIDs in the prevention of damage in the lower GI tract in rheumatologic patients. Preliminary studies in healthy volunteers have shown that these drugs are associated with no or less small bowel damage than tNSAIDs plus PPI, although their long-term effects in patients need to be properly tested. Post hoc analysis of previous outcome studies focused on complications of upper GI tract or cardiovascular events have shown contradictory results. Data from one ongoing trial comparing celecoxib versus diclofenac plus PPI and examining serious outcomes from the whole GI tract will probably provide new insights in this area.

Nimesulide inhibits crypt epithelial cell proliferation at 6 hours in the small intestine in CD-1 mice

To determine whether the gut-sparing selectivity of cyclooxygenase-2 inhibitors is related to early crypt kinetic mechanisms, this study compared the primary effects on small intestinal mucosal epithelial cell proliferation and morphometry of a nonselective dual cyclooxygenase inhibitor, indomethacin, with a cyclooxygenase-2 selective inhibitor, nimesulide. Indomethacin downregulated the crypt cell production rate in the proximal small intestine, and nimesulide reduced cell proliferation in the proximal and distal small intestine. Compared to controls, there were smaller proliferating compartments in the crypts in midintestinal segments in both indomethacin- and nimesulide-treated groups, but more dividing cells in the distal intestine in indomethacin-treated group. Crypt cellularity, numbers, and width were unchanged from control values in both treated groups, suggesting a reduction in crypt cell emigration. Despite its selectivity for inhibiting cyclooxygenase-2, nimesulide induces similar but widespread initial effects on intestinal cell kinetics when compared to indomethacin.

Nimesulide alters cell recruitment into mitosis in murine intestinal crypts without influencing the cell production rate

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) that exhibit COX-2 selectivity is associated with fewer gastrointestinal side effects than seen with more traditional NSAIDs. To determine whether the early effects on cell kinetics in the intestinal mucosal epithelium described after COX-2 selective inhibition are sustained following continuous therapy with these inhibitors, assessments of morphometry and cryptal cell proliferation in the murine small intestinal mucosa were made at 24 hr after treatment with indomethacin, a dual COX inhibitor (10 mg/kg body weight intraperitoneally), nimesulide, a selective COX-2 inhibitor (15 mg/kg body weight intraperitoneally), or vehicle. Nimesulide-treated intestine was elongated beyond control values, in contrast to the shorter indomethacin-treated intestine, but anomalous villous forms were present in both treated groups. Both treatments induced expansion and contraction of proliferating compartments in the crypts in different regions of the intestine but nimesulide did not alter crypt cell production rates, in contrast to the down-regulation induced by indomethacin. These findings may provide some of the fundamental basis for the gut-sparing properties seen in patients treated with COX-2 selective inhibitors.

The incidence of Proteus mirabilis infection increases in patients on treatment but does not trigger disease activity

The aim of this study is to determine whether treatment increases the levels of anti-Proteus antibodies (APA) in patients with rheumatoid arthritis (RA). The blood samples of 32 patients suffering from RA who were recruited in our previous study and continued to participate in our follow-up study were collected after 1 year. Their first and follow-up samples were analysed for the presence of IgG isotype and total immunoglobulins (IgG+IgA+IgM) against Proteus mirabalis (PM) using enzyme-linked immunosorbent assay with two kinds of antigen preparations: whole bacteria and sodium dodecyl sulphate (SDS) lysed bacterial extract. All patients were treated with methotrexate and hydroxychloroquine with adequate dose of non-steroidal anti-inflammatory drug. After 1 year, 11 patients were in clinical remission [erythrocyte sedimentation rate (ESR) less than 30 mm/h and C-reactive protein (CRP) less than or equal to 10 mg/l], while the rest of the 21 were in the state of active disease. Correlation and Student's t test were used for statistical analysis. APA titres were significantly elevated in patients after 1 year of therapy. However, the rise was not different between patients who were in clinical remission and those in the state of active disease. APA titre increases in the treatment of RA, and the probable mechanisms are discussed.

Paradox of simultaneous intestinal ischaemia and hyperaemia in inflammatory bowel disease

This review has focused on evidence regarding intestinal perfusion of inflammatory bowel disease (IBD). Basic investigation has defined an altered microvascular anatomy in the affected IBD bowel, which corresponds with diminished mucosal perfusion in the setting of chronic, long-standing inflammation. Diminished perfusion is linked to impaired wound healing, and may contribute to the continued refractory mucosal damage, which characterizes IBD. Alterations in vascular anatomy and physiology in IBD suggests additional possible mechanisms by which micro-vessels may contribute to the initiation and perpetuation of IBD. This begs the following questions: will angiogenesis within the gut lead to sustained inflammation, does the growing vasculature generate factors that transform the surrounding tissue and does angiogenesis generate vascular anastomosis within the gut, with shunting of blood away from the mucosal surface, impairment of metabolism and potentiation of gut damage? Further studies are required to define the mechanisms that underlie the vascular dysfunction and its role in pathophysiology of IBD.

Visible small-intestinal mucosal injury in chronic NSAID users

BACKGROUND & AIMS

Patients who regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) have an increased risk for small-intestinal mucosal ulceration and bleeding, which may present as anemia of undetermined gastrointestinal origin or protein loss. The prevalence and severity of small-intestinal lesions remains unclear. Our aim was to assess the frequency of NSAID-induced small-bowel injury among chronic NSAID users.

METHODS

Ambulatory patients with various types of arthritides who took NSAIDs daily (>3 mo duration) or took either acetaminophen alone or nothing were enrolled in the study. All patients fasted overnight and underwent wireless video capsule endoscopy. Two investigators, blind to therapy, reviewed each video beginning after the pylorus. Lesions were scored as normal, red spots, small erosions, large erosions, or ulcers. An ulcer was defined as a larger lesion with apparent depth and a definite rim.

RESULTS

Forty-one patients, 36 men and 5 women, ages ranging from 22 to 66 years (mean age, 49.8 y) were analyzed including 21 chronic NSAID users and 20 control patients. Small-bowel injury was seen in 71% of NSAID users compared with 10% of controls (P < .001). Injury was mild (few or no erosions, absence of large erosions/ulcers) in 10 NSAID users compared with 2 controls. Five NSAID users had major (>4 erosions or large ulcers/ulcers) damage compared with none in the control group. There were no complications or problems with the capsule endoscopy procedure.

CONCLUSIONS

Endoscopically evident small-intestinal mucosal injury is very common among chronic NSAID users. The role of endoscopically evident injury in unexplained iron-deficiency anemia and hypoalbuminemia among chronic NSAID users remains undetermined.

Mucosal inflammation in a genetic model of spontaneous type I diabetes mellitus

The BioBreeding (BB) rat provides a model of spontaneous type I diabetes mellitus that closely resembles the human disease. Diabetes-prone BB rats demonstrate increased intestinal permeability prior to the development of insulinitis. Studies suggest that alterations in intestinal permeability can lead to increased intestinal inflammatory activity. Diabetes-prone (BBdp) and diabetes-resistant (BBdr) BB rats were examined at 45 days and at >70 days of age following the development of clinical disease (BBd). In separate experiments, tissue was assayed for myeloperoxidase (MPO) or fixed for histological assessment and immunohistochemistry. Blood was obtained for leukocyte MPO measurements and morphological assessment of circulating leukocytes. MPO activity was significantly elevated in the distal small intestine of 45-day-old BBdp rats. In contrast, at >70 days of age, MPO activity was significantly increased throughout the small intestine of BBd and non-diabetic BBdp rats. Subsequently, all measurements were performed in >70-day-old rats. An increase in inflammatory infiltrate was noted in the distal small intestine of BBd rats by light microscopy. Infiltrating cells were identified as bands (a maturing cell type of the neutrophil lineage) and mature neutrophils. The findings suggest diabetes susceptibility is associated with an increase in intestinal inflammatory activity.

Review article: the gastrointestinal safety profile of rofecoxib, a highly selective inhibitor of cyclooxygenase-2, in humans

Highly selective inhibitors of cyclooxygenase-2, such as rofecoxib, are hypothesized to have an improved gastrointestinal tolerability and safety profile compared with non-selective NSAIDs, which inhibit cyclooxygenase-1 and cyclooxygenase-2 non-selectively. This paper reviews data from randomized, double-blind, placebo-controlled studies which investigated the effects of rofecoxib and NSAIDs on the human gastrointestinal tract. In healthy subjects, rofecoxib 25 mg and 50 mg daily had no effect on gastric mucosal prostaglandin synthesis, whilst naproxen 1000 mg daily caused a 70% reduction. Therapeutic doses of rofecoxib 25 mg and 50 mg daily did not increase intestinal permeability or faecal blood loss in healthy subjects, whereas increases in both measures were seen with indometacin 150 mg or ibuprofen 2400 mg. A supra-therapeutic dose of rofecoxib (250 mg) given daily for 7 days did not induce an increase in gastroduodenal erosions in healthy subjects, whilst increased numbers of erosions were found in subjects given ibuprofen 2400 mg or aspirin 2600 mg. The endoscopic findings in healthy subjects were confirmed in two 6-month clinical studies involving 1516 patients with osteoarthritis; the incidences of ulcers following rofecoxib 25 mg or 50 mg daily were similar to placebo and less than ibuprofen 2400 mg. The advantage of rofecoxib over NSAIDs in these studies appears to translate into clinically relevant benefits; an analysis of 5435 patients with osteoarthritis found a significantly lower incidence of gastrointestinal perforations, ulcers and bleeds in patients taking rofecoxib compared with patients taking NSAIDs. Overall, the findings from these studies suggest that, as a result of cyclooxygenase-1 sparing, rofecoxib is significantly less gastrotoxic than non-selective NSAIDs, and may not differ from placebo.

A randomized trial measuring fecal blood loss after treatment with rofecoxib, ibuprofen, or placebo in healthy subjects

PURPOSE

Gastrointestinal microbleeding, as assessed by the measurement of (51)chromium-labeled red blood cells, is a marker of the mucosal injury associated with the use of nonsteroidal anti-inflammatory drugs. This study tested the hypotheses that cyclooxygenase-2 specific inhibition with rofecoxib would cause less fecal blood loss than a therapeutic dose of ibuprofen and would be equivalent to placebo.

SUBJECTS AND METHODS

In this randomized, double-blind group study, gastrointestinal blood loss was assessed by measurement of fecal (51)chromium radioactivity during a 1-week placebo baseline period and during 4 weeks of treatment with rofecoxib (25 mg or 50 mg once daily), ibuprofen (800 mg three times daily), or placebo in 67 healthy subjects. Gastrointestinal blood loss during treatment weeks 2 to 4 (versus the baseline period) was expressed as the geometric mean ratio of fecal radioactivity in weeks 2 to 4 compared with baseline.

RESULTS

Ibuprofen caused significantly (P <0.001) greater gastrointestinal blood loss (geometric mean ratio of 5.2, 95% confidence interval [CI]: 4.2 to 6.3) than the 25-mg dose of rofecoxib (2.6, 95% CI: 2.2 to 3.1), the 50-mg dose of rofecoxib (2.6, 95% CI: 2.2 to 3.0), or placebo (2.1, 95% CI: 1.8 to 2.5). In contrast, gastrointestinal blood loss with both doses of rofecoxib were equivalent to placebo by a predetermined clinical similarity bound.

CONCLUSIONS

In healthy subjects, treatment with rofecoxib, at 2 to 4 times the doses that are currently recommended for the treatment of patients with osteoarthritis, produced significantly less fecal blood loss than a therapeutic dose of ibuprofen and was equivalent to placebo.

Review article: non-steroidal anti-inflammatory drug-induced gastrointestinal permeability

Non-steroidal anti-inflammatory drugs induce damage throughout the entire gastrointestinal tract. Administration of site-specific permeability probes is a non-invasive technique for assessing the functional integrity of the gastrointestinal mucosa. A systematic search tor NSAID-induced permeability studies using MEDLINE and EMBASE, and an analysis of the literature on NSAID-induced gastrointestinal permeability, were carried out. The advantages and disadvantages of the various probes and study protocols are discussed. Identification of the underlying mechanisms of regulatory control of the epithelial tight junction is still needed. A greater appreciation of the pharmacokinetics and distribution of NSAIDs, coupled with gastrointestinal permeability studies, may help delineate the pathogenesis of NSAID-induced gastrointestinal toxicity. Non-invasive tests of gastric, intestinal and colonic permeability have shown promise in both basic research and in clinical practice. While such tests could not replace endoscopy, they may represent clinically useful techniques for identifying patients who would benefit from endoscopy, to assess the response to treatment, and perhaps to predict the clinical course of disease.

Aspirin-like drugs cause gastrointestinal injuries by metallic cation chelation

Aspirin-like (nonsteroidal anti-inflammatory) drugs may cause injuries including ulcers to the gastrointestinal tract by chelation of the divalent and/or multivalent metallic cations in the gastrointestinal mucus and mucosa, as suggested by the chemical properties of these drugs and supported by experimental and clinical data.

Faecal calprotectin shedding after short-term treatment with non-steroidal anti-inflammatory drugs

BACKGROUND

Increased faecal calprotectin shedding indicates gastrointestinal mucosal inflammation.

METHODS

We studied the effect of short-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) on faecal calprotectin shedding in two randomized crossover studies, with treatment regimens of indomethacin or naproxen for 14 days in the first study (n = 16) and lornoxicam or naproxen for 7 days in the second study (n = 18).

RESULTS

The method's reproducibility and stability were satisfactory. Indomethacin and naproxen increased the faecal calprotectin significantly from a base line of 4.7 mg/l to 9.0 mg/l and 8.0 mg/l, respectively. Lornoxicam failed to increase the faecal calprotectin. Shedding after 7 days of naproxen treatment was positively correlated to gastroduodenal mucosal inflammation assessed by endoscopy.

CONCLUSIONS

Although seemingly influenced by concurrent upper airway infections, the study indicates that the calprotectin test may be useful for monitoring the inflammatory response to NSAID treatment, even in short-term setting.

Antiinflammatory drug-induced small intestinal permeability: the rat is a suitable model

Excretion of orally administrated 51Cr-EDTA as a marker of small intestinal permeability (a proposed prerequisite for human enteropathy) is increased by corticosteroids and non-steroidal antiinflammatory drugs (NSAIDs). We have investigated the suitability of the rat as an animal model of small intestinal permeability using orally administered 51Cr-EDTA. We dosed Sprague-Dawley rats with NSAIDs and corticosterone followed by 51Cr-EDTA under conditions reported for humans and measured urinary excretion of the marker. In control rats, the urinary excretion of 51Cr-EDTA exhibited a skewed-to-the-left frequency distribution curve with a median of 2.13% of the dose. No sex-related differences were noticed in the baseline permeability. In male rats, single therapeutically equivalent doses of indomethacin, flurbiprofen, ibuprofen, naproxen, diclofenac, sulindac, nambumetone, and corticosterone, increased the intestinal permeability by different extents with indomethacin eliciting the maximum effect, and the last four drugs showing minimal potencies. Therapeutically relevant doses of aspirin did not have any significant effect. The increase in permeability was dependent upon the NSAIDs dose. Administration of glucose/citrate, misoprostol and sulfasalazine significantly reduced the effect of indomethacin. Misoprostol antagonized the effect of naproxen but H2-antagonists and sucralfate did not. All the above observations made in the rat were similar to those previously reported for humans. Thus the rat is a suitable model for studies of small intestinal permeability.

A comparison of indomethacin with ibuprofen on gastrointestinal mucosal integrity in conventional and germ-free rats

The effects of indomethacin and ibuprofen on gastrointestinal mucosal integrity were studied in conventional and germ-free rats. Only ibuprofen induced significant gastric erosion formation in both conventional and germ-free animals, demonstrating that the presence of micro-organisms is not required in this form of damage. Both indomethacin and ibuprofen caused significant intestinal damage and blood loss in germ-free animals. However, in the conventional counterparts, damage due to indomethacin was enhanced whereas that induced by ibuprofen was not. The results from the present work would suggest that non-steroidal anti-inflammatory drugs such as indomethacin, which are secreted largely in the bile, unlike ibuprofen, may act in concert with bacteria and the constituents of bile to induce, in part, intestinal damage and blood loss.

The pro-drug sulindac may reduce the risk of intestinal damage associated with the use of conventional non-steroidal anti-inflammatory drugs

To test the hypothesis that administration of a non-steroidal anti-inflammatory drug formulated as a pro-drug, inactive as a cyclooxygenase inhibitor until after absorption, might cause less intestinal damage than conventional non-steroidal anti-inflammatory drugs, intestinal permeation to 51Cr-EDTA and mannitol was assessed in healthy volunteers before and after oral treatment for 1 week with either the pro-drug sulindac or the conventional non-steroidal anti-inflammatory drug indomethacin. Indomethacin, but not sulindac, significantly increased intestinal permeation to 51Cr-EDTA and reduced haemoglobin and haematocrit; neither affect mannitol permeation.

Non-steroidal anti-inflammatory drugs and complicated diverticular disease: a case-control study

Fifty patients with severe complications of diverticular disease were compared with two groups of 50 controls, matched for age and sex. The first control group (A) was randomly selected from all emergency hospital admissions, and the second group (B) from patients with uncomplicated diverticular disease. Of the 50 study patients, 24 (48 per cent) were taking non-steroidal anti-inflammatory drugs (NSAIDs) at the time of admission compared with nine (18 per cent) of control group A and ten (20 per cent) of control group B. Both of these differences were statistically significant, indicating a strong association between the ingestion of NSAIDs and the development of severe complications of diverticular disease.

Nutritional status and growth in juvenile rheumatoid arthritis

The specific cause of short stature in juvenile rheumatoid arthritis (JRA) is unknown. One hypothesis links altered growth to inadequate dietary intake. In this study, nutritional status was assessed in 34 children with JRA (8 with systemic JRA, 14 with polyarticular JRA, and 12 with pauciarticular JRA) and 9 healthy controls using 3-day diet records, anthropometrics, and biochemical analyses. Differences in growth were found among the three types of JRA. One third of all subjects were at or below the 10th percentile in height for age (these being predominantly among the systemic and polyarticular groups). With few exceptions, the mean dietary intake for calories and essential nutrients was found to be adequate for each of the three groups. However, more than half of those with systemic JRA reportedly consumed less than the recommended caloric intake for their age and weight. No significant correlations were found linking dietary intake to growth percentiles in any of the groups studied. Biochemical abnormalities were found among the systemic and polyarticular groups. These abnormalities included low plasma levels of vitamins A and C, proteins (albumin, prealbumin, and retinol binding protein) and zinc; and increased levels of copper and glutathione peroxidase activity. Plasma selenium and vitamin E levels were unchanged. The discrepancy between intake and certain circulating nutrient levels may reflect alterations in the requirements, absorption, or use of these nutrients in the presence of chronic inflammation.

51Cr-ethylenediaminetetraacetic acid absorption test. Effects of naproxen, a non-steroidal, antiinflammatory drug

Eighty volunteers were studied to determine the effects of 750 or 1000 mg naproxen daily for a week on intestinal permeability, by means of the 51Cr-ethylenediaminetetraacetic acid (EDTA) absorption test. With 750 mg naproxen (n = 42) the median urinary excretion increased from 2.44% to 3.51% (p less than 0.01), and with 1000 mg (n = 38) from 2.26% to 3.39% (p less than 0.01). When the individual pretreatment absorption was included in the analysis, a statistically significant difference was found between the two doses (19% and 68% median increase as a percentage of base line, respectively (p = 0.04)). Similar results were found in 27 subjects who were given both doses of naproxen. Intraduodenal instillation of the test dose in 18 subjects showed that gastric absorption was negligible, and no correlation was found with upper endoscopy findings, changes in orocoecal transit time, or reported symptoms.

Clinical pharmacology and use of nonsteroidal anti-inflammatory drugs

This review informs clinicians about current clinical usage and pharmacokinetics of newer NSAIDs and aspirin. To understand the effects of these drugs, a review of prostaglandin synthesis and actions is provided.

Importance of intestinal mucosal immunity and luminal bacterial cell wall polymers in the aetiology of inflammatory joint diseases

The distal intestine contains bacterial cell wall polymers capable of inducing acute and chronic polyarthritis if systemically distributed. Parenteral injection of peptidoglycan-polysaccharide (PG-PS) polymers from certain bacterial species produces spontaneously relapsing erosive synovitis in susceptible rat strains, and normally subarthropathic amounts of PG-PS and lipopolysaccharide (endotoxin) can reactivate arthritis initially induced by PG-PS. These experimental results illustrate the inflammatory potential of luminal bacterial products and the importance of genetically determined host susceptibility factors in the pathogenesis of arthritis. Normally, luminal complexing by secretory IgA and an intact epithelial barrier limits uptake of luminal antigen; however, intestinal inflammation enhances mucosal uptake and systemic distribution of potentially injurious macromolecules, including PG-PS and lipopolysaccharide. Occult intestinal inflammation, which may be related to non-steroidal anti-inflammatory drugs or may be disease-associated, occurs in approximately two thirds of patients with rheumatoid arthritis, idiopathic reactive arthritis and ankylosing spondylitis. Enhanced mucosal permeability to macromolecules occurs in rheumatoid arthritis, enteric infections and idiopathic inflammatory bowel disease. Intestinal inflammation is associated with increased mucosal IgG production and circulating immune complexes. Hyperactive IgA synthesis occurs in many types of inflammatory joint disease. Polyclonal IgA is increased in rheumatoid arthritis, Sjögren's syndrome, ankylosing spondylitis, Reiter's syndrome, and reactive arthritis following Yersinia infection. Anti-Klebsiella IgA cross-reacts with HLA-B27 antigen, and antibodies to enteric bacteria are able to lyse lymphocytes from HLA-B27 patients with ankylosing spondylitis. Anti-Yersinia IgA is produced at the mucosa in increased quantities in patients who develop arthritis following Yersinia enteritis, possibly as a consequence of defective cellular immunity. Serum concentrations of IgA correlate with activity of rheumatoid arthritis and ankylosing spondylitis, and serum IgA immune complexes are associated with rheumatoid vasculitis, suggesting that IgA contributes to the pathogenesis of arthritis. We speculate that intestinal injury may also induce or perpetuate arthritis by systemic distribution of inflammatory mediators produced by intestinal immune effector cells.

Misoprostol reduces indomethacin-induced changes in human small intestinal permeability

This study examined whether indomethacin-induced increases in small intestinal permeability in man are prevented by concomitant administration of a prostaglandin analog (misoprostol). Twelve male volunteers were tested as baseline, following misoprostol alone (200 micrograms, at -16, -12, -8.5, -4, -1.5, and +4 hr); following indomethacin alone (75 mg, at -8; 50 mg, -1 hr); and following coadministration of misoprostol and indomethacin as specified above. A 100-ml test solution containing 3-O-methyl glucose (0.2 g), D-xylose (0.5 g), L-rhamnose (1.0 g), and [51Cr]EDTA (100 microCi) was ingested at 8 AM, and a 5-hr collection made for marker analysis to assess active and passive carrier-mediated transport and trans- and intercellular permeation, respectively. Indomethacin increased the permeation of [51Cr]EDTA selectively, and this increase was significantly reduced by the coadministration of misoprostol. These changes were mirrored by changes in [51Cr]EDTA-L-rhamnose urine excretion ratios, which indicates that paracellular permeability was specifically altered. This study supports the suggestion that NSAIDs alter intestinal permeability by a mechanism involving reduced prostaglandin synthesis and indicates that coadministration of misoprostol with NSAIDs may reduce the frequency and severity of NSAID-induced small intestinal inflammation.

Clinicopathological features of nonsteroidal antiinflammatory drug-induced small intestinal strictures

The clinicopathological features in 4 patients are described where nonsteroidal antiinflammatory drugs appear to have caused small intestinal strictures. Two patients had rheumatoid arthritis and 2 patients had osteoarthritis; all had received nonsteroidal antiinflammatory drugs for 1.5-30 yr. Three patients had an initial illness characterized by diarrhea, profound weight loss, and hypoalbuminemia. Intestinal radiology at this stage ranged from subtle changes to those of Crohn's disease. Three patients underwent surgery. At operation the bland external appearance contrasted with the striking mucosal appearances of multiple concentric, circumferential, diaphragmatic strictures that caused luminal stenosis to a pinhole. These septa were due to submucosal fibrosis and the histopathological picture appears to represent a new nosological entity.