Arachidonic acid metabolites and their role in inflammatory bowel disease. An update requiring addition of a pathway

The In Vitro and In Vivo Effect of Lipoxygenase Pathway Inhibitors Nordihydroguaiaretic Acid and Its Derivative Tetra-O-methyl Nordihydroguaiaretic Acid against Brucella abortus 544

This study investigated the contribution of lipoxygenase (LOX) inhibitors, nordihydroguaiaretic acid (NDGA), tetra-O-methyl nordihydroguaiaretic acid (M₄N) and zileuton (ZIL), and thromboxane A2 (TXA₂) inhibitor 4,5-diphenylimidazole (DPI) in the proliferation of Brucella abortus infection. None of the compounds affected the uptake of Brucella into the macrophages. We determined the effect of neutralizing leukotriene B4 (LTB4) receptor and showed that the uptake of the bacteria was inhibited at 30 min post-infection. M₄N treatment attenuated intracellular survival of Brucella at 2 h post-incubation but it was not observed in the succeeding time points. DPI treatment showed reduced survival of Brucella at 24 h post-incubation while blocking LTB4 receptor was observed to have a lower intracellular growth at 48 h post-incubation suggesting different action of the inhibitors in the course of the survival of Brucella within the cells. Reduced proliferation of the bacteria in the spleens of mice was observed in animals treated with ZIL or DPI. Increased serum cytokine level of TNF-α and MCP-1 was observed in mice treated with M₄N or ZIL while a lower IFN-γ level in ZIL-treated mice and a higher IL-12 serum level in DPI-treated mice were observed at 7 d post-infection. At 14 d post-infection, ZIL-treated mice displayed reduced serum level of IL-12 and IL-10. Overall, inhibition of 5-LOX or TXA₂ or a combination therapy promises a potential alternative therapy against B. abortus infection. Furthermore, strong ligands for LTB4 receptor could also be a good candidate for the control of Brucella infection.

PUFA-Induced Metabolic Enteritis as a Fuel for Crohn's Disease

BACKGROUND & AIMS

Crohn's disease (CD) globally emerges with Westernization of lifestyle and nutritional habits. However, a specific dietary constituent that comprehensively evokes gut inflammation in human inflammatory bowel diseases remains elusive. We aimed to delineate how increased intake of polyunsaturated fatty acids (PUFAs) in a Western diet, known to impart risk for developing CD, affects gut inflammation and disease course. We hypothesized that the unfolded protein response and antioxidative activity of glutathione peroxidase 4 (GPX4), which are compromised in human CD epithelium, compensates for metabolic perturbation evoked by dietary PUFAs.

METHODS

We phenotyped and mechanistically dissected enteritis evoked by a PUFA-enriched Western diet in 2 mouse models exhibiting endoplasmic reticulum (ER) stress consequent to intestinal epithelial cell (IEC)-specific deletion of X-box binding protein 1 (Xbp1) or Gpx4. We translated the findings to human CD epithelial organoids and correlated PUFA intake, as estimated by a dietary questionnaire or stool metabolomics, with clinical disease course in 2 independent CD cohorts.

RESULTS

PUFA excess in a Western diet potently induced ER stress, driving enteritis in Xbp1-/-IEC and Gpx4+/-IEC mice. ω-3 and ω-6 PUFAs activated the epithelial endoplasmic reticulum sensor inositol-requiring enzyme 1α (IRE1α) by toll-like receptor 2 (TLR2) sensing of oxidation-specific epitopes. TLR2-controlled IRE1α activity governed PUFA-induced chemokine production and enteritis. In active human CD, ω-3 and ω-6 PUFAs instigated epithelial chemokine expression, and patients displayed a compatible inflammatory stress signature in the serum. Estimated PUFA intake correlated with clinical and biochemical disease activity in a cohort of 160 CD patients, which was similarly demonstrable in an independent metabolomic stool analysis from 199 CD patients.

CONCLUSIONS

We provide evidence for the concept of PUFA-induced metabolic gut inflammation which may worsen the course of human CD. Our findings provide a basis for targeted nutritional therapy.

Simultaneous Quantitation of Lipid Biomarkers for Inflammatory Bowel Disease Using LC-MS/MS

Eicosanoids are key mediators and regulators of inflammation and oxidative stress that are often used as biomarkers for severity and therapeutic responses in various diseases. We here report a highly sensitive LC-MS/MS method for the simultaneous quantification of at least 66 key eicosanoids in a widely used murine model of colitis. Chromatographic separation was achieved with Shim-Pack XR-ODSIII, 150 × 2.00 mm, 2.2 µm. The mobile phase was operated in gradient conditions and consisted of acetonitrile and 0.1% acetic acid in water with a total flow of 0.37 mL/min. This method is sensitive, with a limit of quantification ranging from 0.01 to 1 ng/mL for the various analytes, has a large dynamic range (200 ng/mL), and a total run time of 25 min. The inter- and intraday accuracy (85-115%), precision (≥85%), and recovery (40-90%) met the acceptance criteria per the US Food and Drug Administration guidelines. This method was successfully applied to evaluate eicosanoid metabolites in mice subjected to colitis versus untreated, healthy control mice. In summary, we developed a highly sensitive and fast LC-MS/MS method that can be used to identify biomarkers for inflammation and potentially help in prognosis of the disease in inflammatory bowel disease (IBD) patients, including the response to therapy.

Diagnostic role of computed tomographic enterography differentiating crohn disease from intestinal tuberculosis

OBJECTIVES

The aim of the present study was to evaluate the diagnostic role of computed tomographic enterography (CTE) in distinguishing Crohn disease (CD) from intestinal tuberculosis (ITB).

MATERIALS AND METHODS

From January 2006 to August 2011, a total of 81 consecutive patients (64 patients with CD and 17 patients with ITB) who received CTE on the initial workup were included. In CTE, degree of bowel involvement (number and length), mural change (mural hyperenhancement, stratification, wall thickening, and distribution), adjacent mesenteric change (comb sign, fibrofatty proliferation, fistula, abscess, and lymphadenopathy), and peritoneal change (peritoneal thickening and ascites) were assessed.

RESULTS

Segmental involvement, comb sign, fibrofatty changes, moderate wall thickening, and asymmetric distribution were significantly more common in the patients with CD than those with ITB. A positive comb sign was the most suggestive finding of CD (sensitivity, 74.1%; specificity, 90.9%).

CONCLUSIONS

A positive comb sign is the most suggestive finding that differentiates CD from ITB.

Role of 15-lipoxygenase/15-hydroxyeicosatetraenoic acid in hypoxia-induced pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with a complex aetiology characterized by elevated pulmonary artery resistance, which leads to right heart ventricular afterload and ultimately progressing to right ventricular failure and often death. In addition to other factors, metabolites of arachidonic acid cascade play an important role in the pulmonary vasculature, and disruption of signaling pathways of arachidonic acid plays a central role in the pathogenesis of PAH. 15-Lipoxygenase (15-LO) is upregulated in pulmonary artery endothelial cells and smooth muscle cells of PAH patients, and its metabolite 15-hydroxyeicosatetraenoic acid (15-HETE) in particular seems to play a central role in the contractile machinery, and in the initiation and propagation of cell proliferation via its effects on signal pathways, mitogens, and cell cycle components. Here, we focus on our important research into the role played by 15-LO/15-HETE, which promotes a proliferative, antiapoptotic, and vasoconstrictive physiological milieu leading to hypoxic pulmonary hypertension.

A cell-based assay for screening lipoxygenase inhibitors

Lipoxygenases (LOX) form a family of lipid peroxidizing enzymes within the plant and animal kingdoms. In humans, six functional lipoxygenase isoforms have been identified. 5-LOX, "platelet-type" 12-LOX (p12-LOX) and 15-LOX type 1 (15-LOX1), originally identified in leukocytes, platelets, and reticulocytes, respectively, generate lipid mediators involved in host cellular functions and in the pathophysiology of asthma, cardiovascular diseases, and cancer. The pharmaceutical industry has reinvigorated their programs to develop novel LOX inhibitors in view of recent findings. However, high throughput LOX screening assays to test novel agents against these intracellular enzymes are limited. We describe a cell-based 96-well microplate fluorescence assay tested against several existing LOX inhibitors, and validate the assay by comparing known IC(50) values and HPLC analysis, which may provide a useful screen for novel LOX inhibitors.

Elevated concentrations of linoleic acid in erythrocyte membrane phospholipids in patients with inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn disease (CD), is a disorder characterized by diffuse inflammation of the gastrointestinal tract. The immune response and inflammation are mediated by polyunsaturated fatty acids and influenced by dietary fats and lipid metabolism. This study examined the qualitative and quantitative fat intake of IBD patients and healthy controls on plasma phospholipid and erythrocyte membrane phospholipid (EMP) fatty acid content. Measurement of the fatty acid composition of plasma phospholipid and EMP were performed in 29 UC patients, 20 CD patients, and 31 healthy controls. Anthropometric characteristics and data on dietary intake were also collected. We observed significantly lower lipid intake in UC and CD patients vs controls. The UC and CD patients had significantly higher levels of linoleic acid in their EMP than did controls. There were no significant differences in the levels of n-3 polyunsaturated fatty acids, but there were significantly higher levels of the n-6 in the EMP of UC and CD patients compared with controls. The significant differences persisted after the data were adjusted for potential confounders and lipid intake. Higher levels of linoleic acids and n-6 fatty acids, which are involved in production of proinflammatory mediators, were found in IBD patients compared with controls, thereby implicating n-6 fatty acids in the pathophysiology of the disease.

Drug consumption and the risk of microscopic colitis

BACKGROUND

Microscopic colitis is a rare disease of unknown etiology. It has been described that some drugs could cause or worsen the disease; however, the scientific evidence is limited.

AIM

To investigate the possible association of chronic drug consumption with microscopic colitis.

METHODS

This was a case-control study in which groups of cases were: Group 1-39 patients with collagenous colitis; Group 2-39 patients with lymphocytic colitis; and Group 3-52 patients with chronic watery diarrhea of functional characteristics. 103 subjects formed the control group. At diagnosis, a drug consumption history of at least 2-wk duration was registered. An age- and sex-adjusted logistic regression analysis was used, and the odds ratio (OR, 95% CI) was calculated.

RESULTS

Drug consumption was more frequent in lymphocytic colitis than in the control group (92.3%vs 76.3%, P < 0.05). The mean daily number of drugs by person was also higher in lymphocytic colitis (3.79 +/- 0.44 vs 2.13 +/- 0.22, P= 0.04). The following associations as compared with the control group were observed: Group 1-Consumption of NSAIDs (46.2%vs 23%, OR 2.9, 1.3-6.4), selective serotonin reuptake inhibitors (SSRIs) (18%vs 1%, OR 21, 2.5-177), specifically, sertraline (15.4%vs 0%, P < 0.0005); Group 2-SSRIs (28%vs 1%, OR 37.7, 4.7-304), beta-blockers (13 vs 3%, OR 4.79, 1.04-20), statins (13%vs 3%, OR 4.6, 1.04-20), biphosphonates (8%vs 0%, P= 0.022); Group 3-SSRIs (15%vs 1%, OR 16.2, 2-135), statins (11.5%vs 3%, OR 5.4, 1.2-24). As compared with the chronic diarrhea group, a significant association with the usage of sertraline in LC (P= 0.005) and a trend for NSAIDs in CC (P= 0.057) were found.

CONCLUSIONS

Drug consumption increases the risk of microscopic colitis. Some drugs might be trigger factors of colonic inflammation in predisposed hosts, and others might only worsen self-evolving microscopic colitis.

Essential fatty acid depletion in children with inflammatory bowel disease

OBJECTIVE

Children with inflammatory bowel disease (IBD) suffer from malabsorption and malnutrition and therefore may be at risk of developing polyunsaturated fatty acid (PUFA) deficiency. The aim of this study was to investigate PUFA status in children with IBD and the possible relationship to disease activity and nutritional status.

MATERIAL AND METHODS

We assessed the fatty acid composition of plasma phospholipids (%wt/wt) of 21 children aged 5.5-18 years with IBD (ulcerative colitis, 15; Crohn's disease, 6) with mild or moderate disease activity. The clinical symptoms and biochemical indices of disease activity and nutritional status (lean and fat body mass, Hb, albumin serum conc.) were also determined.

RESULTS

The patients had lower phospholipid PUFAs than 13 healthy, aged-matched controls (25.8+/-5.2 versus 34.2+/-5.7, M+/-SD, p<0.001), mainly due to lower values of linoleic acid (18:2n-6, 14.0+/-3.8 versus 18.3+/-4.3, p<0.01) and its major metabolite arachidonic acid (20:4n-6, 5.3+/-2.0 versus 9.3+/-1.9, p<0.0001). There were also higher values of a-linolenic acid (18:3n-3, 0.3+/-0.4 versus 0.2+/-0.1, p<0.01) while the long-chain n-3 PUFA-eicosapentaenoic and docosahexaenoic acids were normal. Total n-6 PUFA correlated inversely to erythrocyte sedimentation rate (p<0.01), seromucoid (p<0.05) and positively to Hb concentration (p<0.01).

CONCLUSIONS

Children with inflammatory bowel disease have a high risk of n-6 PUFA depletion, which is related to disease activity.

CD4+ T cells from IL-10-deficient mice transfer susceptibility to NSAID-induced Rag colitis

Products of arachidonic acid metabolism are important for mucosal homeostasis, because blockade of this pathway with an NSAID triggers rapid onset of severe colitis in the IL-10 knockout (IL-10(-/-)) model of IBD. Rag mice do not make T or B cells. This study determined whether reconstitution of Rag mice with T cells from IL-10(-/-) mice transferred NSAID colitis susceptibility. Rag mice were reconstituted by intraperitoneal injection with splenocytes from wild-type (WT) or IL-10(-/-) animals. Colitis was induced by using piroxicam and was graded histologically. Isolated lamina propria mononuclear cells (LPMC), lamina propria T cells, and LPMC depleted of T cells from reconstituted Rag mice were studied for cytokine production. Only animals reconstituted with IL-10(-/-) CD4(+) T cells and administered piroxicam developed severe colitis. LPMC from these colitic animals made IFN-gamma, whose production was dependent on T cells. Some IL-10 was produced but only from non-T cells. LPMC from the healthy Rag mice that were reconstituted with WT T cells and were piroxicam resistant made much more IL-10. This was mostly T cell dependent. In conclusion, only CD4(+) T cells from IL-10(-/-) animals leave Rag mice susceptible to NSAID-induced, Th1 colitis. Lamina propria T cells normally make large quantities of IL-10, suggesting that IL-10 from T cells may be protective.

CT of prominent pericolic or perienteric vasculature in patients with Crohn's disease: correlation with clinical disease activity and findings on barium studies

OBJECTIVE. The purpose of this study was to correlate CT findings of prominent pericolic or perienteric vasculature with clinical disease activity, treatment methods, and barium enema study findings in patients with Crohn's disease.

MATERIALS AND METHODS

We retrospectively analyzed 33 patients with Crohn's disease who had undergone both barium enema study and abdominal CT. CT scans were evaluated for the presence and location of prominent vasculature. On the basis of the Crohn's disease activity index, the patients were assigned to one of three categories--active, intermediate, or quiescent disease groups--and the frequency of prominent vasculature was compared among them. Thereafter, erythrocyte sedimentation rates, C-reactive protein levels, treatment methods, and radiographic findings were compared in groups with and without prominent vasculature.

RESULTS

Prominent vasculature was more frequently found in patients with active disease (81%) than in those with intermediate (33%) and quiescent disease (0%) (p < 0.001). The erythrocyte sedimentation rates and C-reactive protein levels were higher in patients with prominent vasculature (but not at a statistically significant rate). Patients with prominent vasculature were more frequently admitted to the hospital (p = 0.024) and received more aggressive treatment (p = 0.049) than patients without prominent vasculature. The main differences of radiographic findings between the group with prominent vasculature and the group without prominent vasculature included the common occurrence of longitudinal and perpendicular ulceration (p = 0.017 for small bowel; p = 0.041 for colon) and the extensive length of organ involvement (p = 0.004 for small bowel; p = 0.036 for colon).

CONCLUSION

Prominent pericolic or perienteric vasculature seen on CT in patients with Crohn's disease suggests that the disease is clinically active, advanced, and extensive and that these patients require more aggressive treatment than patients without this CT finding.

Mammalian arachidonate 15-lipoxygenases structure, function, and biological implications

Lipoxygenases (LOXs) constitute a heterogeneous family of lipid peroxidizing enzymes capable of oxygenating polyunsaturated fatty acids to their corresponding hydroperoxy derivatives. In mammals, LOXs are classified with respect to their positional specificity of arachidonic acid oxygenation into 5-, 8-, 12-, and 15-LOXs. Arachidonate 15-LOXs may be sub-classified into a reticulocyte-type (type-1) and an epidermis-type (type-2) enzyme. Since the leukocyte-type 12-LOXs are very similar to the reticulocyte-type 15-LOXs, these enzymes are designated 12/15-LOXs. Several LOX isoforms, in particular the reticulocyte-type 15-LOX and the human 5-LOX, are well characterized with respect to their structural and functional properties On the other hand, the biological role of most LOX-isozymes including the reticulocyte-type 15-LOC is far from clear. This review is intended to summarize the recent developments in 15-LOX research with particular emphasis to molecular enzymology and regulation of gene expression. In addition, the major hypotheses on the physiological and patho-physiological roles of 15-LOXs will be discussed briefly.

Inflammatory bowel disease and environmental influences

Some environmental factors have been established firmly as influences on the development of IBD, such as smoking and appendectomy. Other behaviors, such as oral contraceptive use and sugar intake, have been suggested as risk factors, but he data conflict sharply. The importance of other behaviors, such as breast-feeding, is even murkier with sharply divergent data. Some issues studied may not be factors in themselves but rather markers for other unidentified influences. The conflicting evidence in many of these studies may be clarified as specific genes are identified and the interplay between these environmental factors and genetic subtypes is investigated.

Efficacy and safety of oral ridogrel in the treatment of ulcerative colitis: two multicentre, randomized, double-blind studies

BACKGROUND

Ridogrel at low doses inhibits thromboxane synthase. Oral ridogrel, from 5 mg once daily to 150 mg twice daily, improves the endoscopic appearance of colonic mucosa and clinical manifestations in mild to moderate ulcerative colitis.

AIM

One US trial and one international trial were conducted to determine the effect of ridogrel on mild to severe active ulcerative colitis.

METHODS

Two 12-week, double-blind, randomized, parallel-group trials were conducted. A US trial compared 0.5 mg, 2.5 mg and 5 mg of ridogrel once daily with placebo. An international trial compared 0.5 mg of ridogrel once daily with 2.5 mg and 5.0 mg of ridogrel once daily and 800 mg of mesalazine (known as mesalamine in the USA) three times daily. The primary efficacy outcome measure was the rate of complete remission.

RESULTS

In the US trial, complete remission was achieved in 20.8% of patients in the 0.5 mg ridogrel group, 17.9% in the 2.5 mg ridogrel group, 20.6% in the 5.0 mg ridogrel group and 13.6% in the placebo group. In the international trial, 14.4% of patients in the 0.5 mg ridogrel group, 19.6% in the 2.5 mg ridogrel group, 19.4% in the 5.0 mg ridogrel group and 16.4% in the mesalazine group experienced complete remission. In the international trial, rates of complete remission at the end-point were greater in the 2.5 mg and 5.0 mg ridogrel groups than in the 0.5 mg ridogrel group, but the differences were not statistically significant. In the US trial, rates of complete remission at the end-point were greater in the 2.5 mg and 5.0 mg ridogrel groups than in the placebo group, but the differences were not statistically significant. Approximately 30% of the patients in each group discontinued treatment before the 12-week end-point owing to a lack of therapeutic response. All doses of ridogrel were well tolerated and comparable with placebo or mesalazine in terms of safety.

CONCLUSIONS

No significant differences in the primary efficacy outcome measure were found between either the 2.5 mg or the 5.0 mg dose of ridogrel and placebo in the US trial and between either the 2.5 mg or the 5.0 mg dose of ridogrel and the 0.5 mg dose of ridogrel, a surrogate dose for placebo, in the international trial. There was no clear indication in either trial of an effective dose of ridogrel in the treatment of ulcerative colitis.

Electrolyte transport in the mammalian colon: mechanisms and implications for disease

The colonic epithelium has both absorptive and secretory functions. The transport is characterized by a net absorption of NaCl, short-chain fatty acids (SCFA), and water, allowing extrusion of a feces with very little water and salt content. In addition, the epithelium does secret mucus, bicarbonate, and KCl. Polarized distribution of transport proteins in both luminal and basolateral membranes enables efficient salt transport in both directions, probably even within an individual cell. Meanwhile, most of the participating transport proteins have been identified, and their function has been studied in detail. Absorption of NaCl is a rather steady process that is controlled by steroid hormones regulating the expression of epithelial Na(+) channels (ENaC), the Na(+)-K(+)-ATPase, and additional modulating factors such as the serum- and glucocorticoid-regulated kinase SGK. Acute regulation of absorption may occur by a Na(+) feedback mechanism and the cystic fibrosis transmembrane conductance regulator (CFTR). Cl(-) secretion in the adult colon relies on luminal CFTR, which is a cAMP-regulated Cl(-) channel and a regulator of other transport proteins. As a consequence, mutations in CFTR result in both impaired Cl(-) secretion and enhanced Na(+) absorption in the colon of cystic fibrosis (CF) patients. Ca(2+)- and cAMP-activated basolateral K(+) channels support both secretion and absorption of electrolytes and work in concert with additional regulatory proteins, which determine their functional and pharmacological profile. Knowledge of the mechanisms of electrolyte transport in the colon enables the development of new strategies for the treatment of CF and secretory diarrhea. It will also lead to a better understanding of the pathophysiological events during inflammatory bowel disease and development of colonic carcinoma.

Effect of intrarectal prostaglandin E2 analogue (enprostil) on trinitrobenzenesulphonic acid-induced colitis in rats

Prostaglandins exert a protective effect on colonic mucosa in experimentally induced colitis. This study investigated the effect of enprostil, a prostaglandin E2 (PGE2) analogue, on trinitrobenzenesulphonic acid (TNBS)-induced colitis in rats. Each rat received a rectal enema containing TNBS (30 mg), followed 24 h later by intrarectal once-daily enprostil (200 microg). Enprostil-treated and control rats were killed on day 3 (enprostil group, n = 5; control, n = 6) or day 10 (enprostil group, n = 5; control, n = 5) after TNBS treatment. The area of damaged mucosa of the colon was measured relative to the total colonic area. We also determined the macroscopic score of mucosal damage, and measured PGE2, 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) and thromboxane B2 (TXB2) concentration in portal vein blood samples. Enprostil significantly reduced both the area of damaged mucosa (including the ulcer area) and the macroscopic score after 3 days' treatment compared with control. Similarly, enprostil significantly reduced plasma concentration of PGE2, 6-keto-PGF1alpha and TXB2 during the acute phase at day 3 of treatment compared with control, but not at day 10. These results suggest that PGE2 enema may have therapeutic potential for treating patients with proctitis or left-sided colitis.

Eicosanoids and the large intestine

During the past three decades, many studies have been conducted to determine the precise role of eicosanoids in colorectal physiology and pathophysiology. This research has increased our understanding of bioactive lipid signaling, and may contribute to the development of more effective therapeutic modalities for digestive diseases in the future. The purpose of this report is to provide a brief overview of the role of eicosanoids in the colon and rectum. This information has been organized according to both functional and disease-related categories. The role of eicosanoids in colonic secretion, motility, inflammatory bowel disease, and colorectal neoplasia will be discussed.

Is administration of n-3 fatty acids by mucosal enema protective against trinitrobenzene-induced colitis in rats?

We investigated the protective role of fish oil (FO-source of n-3 FA) enriched diet (in the first protocol) in 20 rats and FO administration intrarectally (in the second protocol) in 40 rats with trinitrobenzene (TNB) colitis. All colonic specimens were pathologically evaluated, myeloperoxidase enzyme activities were measured, leukotriene B4 (LTB4) and LTC4 levels were determined by radioimmunoassay. In the first protocol 10 rats (group A1) were fed with 8% sunflower and cotton oil enriched diet and (group A2) with 8% FO enriched diet for 6 weeks. At the end of this period, TNB (30 mg in 0.25 ml of 30% ethanol) were intrarectally administered. After 2 weeks, rats were sacrificed. MPO activities (2.47 versus 30.17), LTB4 (34.5 versus 903.3) and LTC4 (77.7 versus 456.0) levels were significantly reduced in group A2 compared with group A1 (P<0.005). There was also a significant difference in pathologic scores (1.55 versus 2.12, P<0.002) between two groups. In the first part of the second protocol, 20 male rats were randomized into two equal groups (B1 and B2) and TNB colitis was induced. After 1 day, 1 ml of saline (group B1) or n-3 FA enemas (group B2) were administered every day for 2 weeks. At the end of this period, rats were sacrificed and evaluated as done for previous groups. Although there was no significant difference between the two groups in comparison with MPO enzyme activities and pathologic scores, the LTB4 (130.1 versus 971.0) and LTC4 (126.0 versus 532.0) levels of FO group were significantly reduced (P<0.005). In the second part of the second protocol, 20 male rats were randomized into two groups. One millilitre of saline (group B3) or FO enemas (group B4) were administered to rats every day for 3 days. At the fourth day, TNB-colitis was induced and after 24 h rats were sacrificed. We could not find any significant difference in MPO activities, pathologic scores, LTB4 and LTC4 levels between groups B3 and B4. In conclusion, FO enriched diet decreased both pathologic damage and tissue LT levels. The second protocol of our study revealed that the long-term FO enemas decreased the LTB4 and LTC4 levels; however, did not have any beneficial effect on the tissue lesions. Short periods of FO enemas did not have a protective role in the occurrence of experimental colitis. The present study showed that FO enemas significantly decreased LT levels. The protective effect of FO (oral and enema) in TNB colitis may open a new insight into the treatment of inflammatory bowel disease.

The effect of immunization with porins on gut pathophysiological response in rats infected with Salmonella typhimurium

Attachment of Salmonella typhimurium to epithelial surfaces elicit significant alterations in different cell signalling events which lead to the development of disease. The present investigation was conducted to evaluate the effect of immunization of rats with porins, on gut physiologic markers following challenge with S. typhimurium. Male albino Wistar rats were immunized with purified porins and challenged by intragastric infection with S. typhimurium. Electrolyte transport, levels of different second messengers and inflammatory mediators were studied. A net absorption of transepithelial fluxes of Na+ and Cl- in immunized-challenged group and secretion in infected group was found. Ca2+ and 3-O-methyl-D-glucose fluxes did not show any change. Significant increase in the levels of [Ca2+]i, cAMP, membrane form of protein kinase C, prostaglandins, NADPH oxidase, Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, total oxygen free radicals, reactive nitrogen intermediates, citrulline and lipid peroxidation was found in the infected group. However, in the immunized-challenged group, the values of all the parameters were found to be almost the same as that of control as well as immunized groups. Na+, K+-ATPase and calmodulin levels were unaltered in all the groups of animals. The results of this study thus suggest that immunization of rats with purified Salmonella porins followed by subsequent challenge with the organism might be helpful for the prevention of multiple physiologic derangements in isolated ileal cells.

L-glutamine enemas attenuate mucosal injury in experimental colitis

PURPOSE

The aim of this study was to investigate the role of 1-glutamine, short chain fatty acid, prednisolone, and mesalazine (5-aminosalicylic acid) enemas on mucosal damage and inflammation in experimental colitis.

METHODS

Colitis was induced in rats with trinitrobenzene sulfonic acid in ethanol. Saline (n = 14), prednisolone (n = 13), 5-aminosalicylic acid (n = 14), 1-glutamine (n = 14), and short chain fatty acid (n = 13) enemas were applied twice daily to the rats for seven days after the induction of colitis. The sham group (n = 9) received only saline enemas. Rats were killed at the seventh day and their colonic macroscopic inflammatory scores were determined. Colonic mucosal gamma glutamyl transpeptidase activity and colonic mucosal malondialdehyde levels were measured. The same measurements but no enemas were done in the control group (n = 7).

RESULTS

There were significant differences in macroscopic inflammatory scores between sham and colitis groups (P < 0.001). The macroscopic inflammatory scores of the colitis group were higher than the short chain fatty acid and glutamine groups (P < 0.05). Whereas the mucosal gamma glutamyl transpeptidase activity was diminished in prednisolone, 5-aminosalicylic acid, and short chain fatty acid groups when compared with the control group; in the colitis, sham, and glutamine groups the activity of this enzyme did not change. The mucosal malondialdehyde levels were significantly lower in the prednisolone and glutamine groups than in the colitis group.

CONCLUSION

Only one of four agents tested, namely, 1-glutamine enemas, could decrease the severity of colitis both morphologically and biochemically. Moreover, L-glutamine prevented the colitis-induced oxidant injury in the colonic mucosa. On the other hand, prednisolone and short chain fatty acids seemed to improve only the physiologic changes of colitis.

Lipid treatment of inflammatory bowel disease

The aetiology of inflammatory bowel disease remains unclear. Local mediators such as arachidonic acid metabolites and peptide mediators (cytokines) appear to contribute to the disease process. The successful administration of neutralizing antibodies against TNF-alpha has confirmed a pathophysiological role for this cytokine in Crohn's disease. Established therapy of inflammatory bowel disease with 5-aminosalicylic acid compounds has been shown to reduce local leukotriene B4 formation by inhibiting lipoxygenases. This therapeutic mechanism formed one rationale for examining the effect of n-3 fatty acids, which also inhibit leukotriene B4 formation, on the course of these diseases. In the first study, published in 1989, we found no beneficial effects of n-3 fatty acids in patients with Crohn's disease; however, there was clinical improvement, just falling short of significance, in patients with ulcerative colitis. Since then two uncontrolled and five controlled studies have further investigated the therapeutic effect of n-3 fatty acids in patients with ulcerative colitis. The size of the patient population in the controlled studies ranged from 10 to 96 patients in the largest study. Two of these studies showed a significant improvement in clinical activity and a steroid-sparing effect, respectively. Another study found only a trend towards improvement and one trial, which also included a treatment group receiving evening primrose oil, found no beneficial effect in the 16 patients receiving n-3 fatty acids. A large, 2 year trial of n-3 fatty acids in patients with ulcerative colitis off steroids, which was recently completed at the Universities of Munich and Mainz, showed a delay of the first episode of relapse, but no reduction in the cumulative relapse rate at 2 years. Controversial results have been published for Crohn's disease. A new enteric-coated formulation reportedly increased the proportion of patients in remission where as another trial using a conventional preparation found no significant effect.

Autoimmunity to tropomyosin isoforms in ulcerative colitis (UC) patients and unaffected relatives

Autoimmunity to cytoskeletal protein tropomyosin (TM) has been demonstrated in UC. However, the TM isoforms involved in this IgG-mediated autoimmune response in UC and the possible presence of serum IgG antibodies against TM (hTMs IgG) in unaffected UC relatives are unknown. The aim of this study was to investigate the human TM (hTM) isoforms recognized by serum IgG from UC and to explore whether hTM IgG antibodies are present in healthy UC relatives. We studied 33 UC patients with 58 unaffected relatives, 31 Crohn's disease (CD) patients with 31 unaffected relatives and 20 controls (C). Serum IgG against four recombinant hTM isoforms (hTM1, 2, 3, 5) were tested by ELISA. p-ANCA were tested by ELISA and immunofluorescence. Serum hTM1 and hTM5 IgG were higher in UC patients than in CD and C (P<0.005). Among UC patients 52% were seropositive for hTM1 and 64% for hTM5 (P<0.001 versus CD and C). In UC, hTM5 IgG were higher in p-ANCA+ than in ANCA- patients (P=0.04). In UC relatives hTM1 IgG were higher than in CD relatives and C (P<0.01). UC relatives were more frequently seropositive for hTM1 than hTM5 IgG (P=0.001). while probands were more frequently seropositive for hTM5 IgG (P=0.008). We conclude that autoimmunity to hTMI and hTM5 is a feature of UC, while hTM1 IgG differentiate UC relatives from controls. A genetic susceptibility to immune recognition of hTM isoforms in UC is suggested.

Relevance of irinotecan hydrochloride-induced diarrhea to the level of prostaglandin E2 and water absorption of large intestine in rats

For characterization of the mechanism(s) of severe diarrhea due to the anticancer agent, irinotecan hydrochloride (CPT-11), examination was made of the relation of CPT-11-related diarrhea to colonic prostaglandin E2 (PGE2) and water absorption in rats. Acute diarrheal symptoms were observed within 1 hr after the administration of CPT-11 to rats, with increased PGE2 and decreased water absorption in the colon. Treatment with atropine at 1 mg/kg, s.c. was noted to inhibit intestinal PGE2 and the CPT-11-related acute diarrheal symptoms, indicating that these diarrheal symptoms were mediated through the cholinergic nervous system accelerated functionally by CPT-11. On the other hand, daily treatment of CPT-11 at the same dose resulted in chronic diarrheal symptoms in all animals 3 days after CPT-11 treatment. Histopathological changes observed in the descending colon and ileum of the rats included degeneration and necrosis of villi and cryptal cells and a decrease in the number of the goblet cells. Significantly increased PGE2 and impaired water absorption of the descending colon were also observed during the chronic diarrheal stage. It can be considered that the chronic diarrheal symptoms appear as a consequence of the gastrointestinal injury characterized by significant increase in PGE2 accompanied by impaired water absorption.

Biochemical tests in diseases of the intestinal tract: their contributions to diagnosis, management, and understanding the pathophysiology of specific disease states

Biochemical testing plays a major role in the complete evaluation of patients with suspected or established intestinal disease. We have classified these tests according to the medium in which they are performed: breath tests, including isotopic and nonisotopic tests, fecal tests, urine tests, serum tests, tissue tests, and other tests. The principles of various tests are outlined, and the role of each test in the evaluation of particular gastrointestinal disorders is discussed.

Anorectal fistula: an unusual presentation in a Crohn's disease patient

An unusual case of an anorectal fistula presenting with hip pain and extensive lower limb muscle wasting in a patient with Crohn's disease is reported. This report emphasizes the important role of a thorough history, a complete physical examination, and a thorough search for evaluating such cases. Any progressive local irritation and pain in a Crohn's disease patient may indicate possible fistulous involvement. Nonspecific laboratory findings such as leukocytosis, anemia, decreased albumin level, and thrombocytosis may be considered as supportive indicators. Barium contrast studies and enhanced computed tomography scan may be helpful but can be falsely negative in the presence of a fistula, as in this case. These findings illustrate that the clinician must not be dissuaded from the diagnosis simply based on negative radiological findings because the presence of a fistula may be impossible to determine preoperatively.

IL-1 stimulates intestinal myofibroblast COX gene expression and augments activation of Cl- secretion in T84 cells

Because interleukin-1 (IL-1) is an important mediator in the inflamed intestine, its effects on enterocyte-subepithelial myofibroblast (SEMF) interaction were investigated in vitro. Acutely juxtaposing T84 cells with 18Co or P2JF SEMF preincubated with IL-1 alpha significantly enhanced T84 short-circuit current (Isc) responsiveness to secretagogues in comparison to SEMF not activated by IL-1 alpha. The sensitivity of T84 cell Isc to Ca(2+)-dependent, but not adenosine 3',5'-cyclic monophosphate-dependent, secretagogues was augmented by IL-1 alpha-treated SEMF. These effects of IL-1 alpha are directly correlated with SEMF prostaglandin E2 (PGE2) production. Both IL-1 alpha augmentation of Cl secretagogue responsiveness and PGE2 formation were inhibited by IL-1 receptor antagonist. Within 5 h, IL-1 alpha stimulated a 10-fold increase in cyclooxygenase (COX)-2 steady-state mRNA levels in 18Co cells. In contrast, COX-1 message levels increased more slowly to two- to threefold above control levels after 24 h incubation. These results demonstrate that the proinflammatory cytokine IL-1 alpha accentuates intestinal SEMF augmentation of enterocyte responsiveness to Ca(2+)-dependent CI-secretagogues. PGE2 is an important mediator of SEMF-enterocyte interaction. The effects of IL-1 alpha on SEMF PGE2 productions are, at least in part, due to stimulation of COX gene expression.

Massive secretory diarrhea and pseudo-obstruction as the initial presentation of Crohn's disease

We report large-volume secretory diarrhea and intestinal pseudo-obstruction in a man whom ultimately proved to have Crohn's disease that responded to sulfasalazine and steroids with resolution of all his symptoms. Although this is an unusual presentation, Crohn's disease should be included in the differential diagnosis in patients whose initial symptoms are intestinal pseudo-obstruction and secretory diarrhea.

Eicosanoids and inflammatory bowel disease

IBD is a disease of unknown cause that involves an amplification of the inflammatory response in the intestinal mucosa. Although not the only offending agents leading to the disease, eicosanoids, the collective group of AA metabolites, may a significant role in the pathogenesis of IBD. This article reviewed the biochemical pathways of eicosanoid formation and the clinical relevance of eicosanoids to IBD. Potential strategies designed to interfere with various aspects of AA metabolism were also outlined. Further clinical trials of newer compounds may soon prove them effective in the management of IBD.

Soluble Fc gamma receptor III (CD 16) and eicosanoid concentrations in gut lavage fluid from patients with inflammatory bowel disease: reflection of mucosal inflammation

BACKGROUND

Activated neutrophils cause tissue injury in inflammatory bowel disease (IBD). Upon activation, they shed soluble Fc gamma IIIb receptors (sFc gamma RIIIb). The subsequent inflammatory response is modulated by several mediators, including neutrophil derived leukotriene B4 (LTB4), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2). The aim of this study was to determine the value of gut lavage sFc gamma RIII and eicosanoid measurements for the assessment of mucosal inflammation in IBD.

METHODS

A total of 18 patients with active IBD, 10 ulcerative colitis (UC), and eight Crohn's disease (CD), and 12 control patients underwent whole gut lavage. Disease activity, endoscopic appearance, and histopathology were graded. Samples were processed for the determination of sFc gamma RIIIb, LTB4, PGE2, and TXB2.

RESULTS

Soluble Fc gamma RIIIb concentrations were increased in both IBD groups. Significant correlations were seen between sFc gamma RIIIb and LTB4 values with histology scores. Mean eicosanoid lavage fluid concentrations in control patients were 14.1 pg/ml for LTB4, 5.6 pg/ml for PGE2, and 397 pg/ml for TXB2. Concentrations of all eicosanoids in IBD patients were significantly increased: LTB4 in UC: mean 73.2 pg/ml, in CD: 96.4 pg/ml (both p < 0.01 v controls). PGE2 in UC: 20.2 pg/ml, in CD: 43.4 pg/ml (p < 0.01). TXB2 in UC: 719.3 pg/ml, in CD: 180.6 pg/ml (both p < 0.05).

CONCLUSIONS

Whole gut lavage fluid analysis is an effective method to study mucosal eicosanoid production. Soluble Fc gamma RIIIb concentrations in gut lavage fluid closely correlate with histological signs of mucosal inflammation and with lavage LTB4 concentration. These data suggest that lavage Fc gamma RIIIb assessment may be used as a simple assay to estimate mucosal neutrophil infiltration in IBD.

Role of cytokines and platelet-activating factor in inflammatory bowel disease. Implications for therapy

BACKGROUND

Platelet-activating factor (PAF) and cytokines, such as interleukins, tumor necrosis factor, and others, are thought to play a role in the inflammatory process involving gastrointestinal disorders such as Crohn's disease, ulcerative colitis, ischemic colitis, or antibiotic-associated colitis.

PURPOSE

This study was undertaken to review the latest literature on the role of PAF and cytokines in the genesis of inflammatory bowel disease and implications for therapy and management.

RESULTS

PAF is an endogenous phospholipid involved in hypersensitivity and inflammatory reactions such as platelet and neutrophil aggregation, vasodilation, increased vascular permeability, and leukocyte adhesion, which have been associated with inflammatory processes. Cytokines are peptides that regulate and coordinate inflammatory and immunologic responses. Increased production of cytokines has been reported during Crohn's disease and ulcerative colitis and is correlated with disease activity.

CONCLUSIONS

Because PAF and cytokines may have an important role in the pathogenesis of inflammatory bowel disease, their inhibition by specific antagonists, mediators, or other agents such as steroids may have a potential therapeutic benefit in treatment and management of these inflammatory diseases in the near future.

Prevalence of essential fatty acid deficiency in patients with chronic gastrointestinal disorders

Patients with chronic intestinal disorders causing malabsorption, nutritional losses through diarrhea, or catabolic illness would be expected to have essential fatty acid (EFA) deficiency (EFAD), but such deficiency has not been demonstrated in patients treated in accordance with the prevailing standard of care. We studied plasma fatty acid patterns of 56 reference or control subjects and 47 patients with chronic intestinal disorders (mostly Crohn's disease) using high-resolution capillary column gas-liquid chromatography. Patients exhibited a shift in fatty acid metabolism similar to that previously shown to be associated with EFAD. Compared with control subjects, patients had (1) decreased polyunsaturated fatty acid (PUFA) levels (43.7% v 50.4%, P < .0001), (2) increased monounsaturated fatty acid (MUFA) levels (25.8% v 22.0%, P < .0001), (3) higher ratios of mead (20:3 omega 9) to arachidonic (20:4 omega 6) acid (0.020 v 0.013, P < .04), and (4) lower concentrations of total (214 v 284 mg/dL, P < .01), saturated ([SFA] 63 v 75 mg/dL, P < .001), MUFA (56 v 63 mg/dL, P < .001), and PUFA (93 v 143 mg/dL, P < .001). Patients had metabolic shifts toward increased production of MUFA and an increased ratio of derivatives to precursors of omega 6 fatty acids, shifts that occur when cells are EFA-deficient. More than 25% of the patients had biochemical evidence of EFAD according to at least one criterion. Optimal diagnosis requires a concurrent evaluation of concentrations of fatty acids in plasma and in lipoproteins (percent fatty acids). On indices of EFA status that depend on percents, ratios, or concentrations of fatty acids or on the production of abnormal fatty acids, the patients were between patients with severe whole-body EFAD and healthy subjects, a state referred to as absolute EFA insufficiency. Patients with chronic intestinal disease should be evaluated for likely EFA deficiencies and imbalances, and treated with substantial amounts of supplements rich in EFAs, such as oral vegetable and fish oils, or intravenous lipids if necessary.

Eicosanoids and the gastrointestinal tract

Determining the role of eicosanoids in gastrointestinal physiology and pathophysiology has been an active area of investigation over the past 20 years. The landmark discovery of prostaglandin endoperoxide synthase and other enzymes involved in the production of arachidonic acid products (lipoxygenases and epoxygenases) ushered in a new era of research. The goal of this review is to distill a large body of work pertaining to studies of eicosanoids in the gastrointestinal tract. This review has been organized according both to functional (secretion and motility) and disease-related (inflammation, mucosal injury, and neoplasia) effects. The aim of this article is to present a clear summary of this area of gastroenterology so that future research can be directed in a logical and productive manner.

Spiral CT demonstration of hypervascularity in Crohn disease: "vascular jejunization of the ileum" or the "comb sign"

OBJECTIVE

To report spiral CT imaging features of the vascular alterations observed in active, early, or recurrent Crohn disease of the small bowel and colon.

METHODS

Spiral CT examinations of the abdomen and pelvis following oral and intravenous contrast were performed in two cases of active Crohn disease.

RESULTS

Spiral CT features of hypervascularity involving the mesenteric vessels of affected segments of bowel include vascular dilatation, tortuosity, and conspicuous prominence and wide spacing of the vasa recta (the "comb" sign). This is attributed to the factors of increased flow and the fibrofatty proliferation in the mesentery and serosa of the affected bowel.

CONCLUSION

Clinical application of these observations may enhance the diagnosis of Crohn disease presenting initially or as an acute recurrence in the differential diagnosis from other conditions.

Jejunal release of prostaglandin E2 in Crohn's disease: relation to disease activity and first-degree relatives

Patients with Crohn's disease of the distal ileum show increased permeability to hyaluronan and increased release of histamine and complement components in uninvolved parts of the proximal jejunum. These abnormalities are related to disease activity, and are not found in first-degree relatives. Increased synthesis of prostaglandins has been observed in inflamed areas of the intestine in active Crohn's disease. Our purpose was to measure luminal prostaglandin release in patients with active and inactive Crohn's disease and their first-degree relatives. Twenty-four patients with Crohn's disease of the distal ileum (10 in remission and 12 with inflammatory activity) and 17 of their first-degree relatives were included and compared with healthy control subjects (n = 39). Ten centimetres of the proximal jejunum was isolated between balloons as described previously and perfused with a balanced electrolyte glucose-containing solution. Luminal concentrations of PGE2 and albumin were measured and their luminal release was calculated. Luminal release of PGE2 was significantly higher in patients with Crohn's disease than in control subjects [69.7 +/- 11.5 and 34.0 +/- 4.7 pg/cm per h (3.7 +/- 0.6 and 1.8 +/- 0.3 ng/L), respectively, P < 0.01]. The PGE2 levels, however, were not positively correlated to disease activity. Furthermore, there was a modest, but significant increase in luminal PGE2 in first-degree relatives [53.6 +/- 7.0 pg/cm per h (2.9 +/- 0.4 ng/L), P < 0.05]. These changes were not accompanied by significant changes in luminal permeation of albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on peroxisomes of colonic mucosa in Crohn's disease

The etiology and pathogenesis of Crohn's disease, a chronic inflammatory bowel pathology, have not been elucidated yet. In particular, the behavior of peroxisomes in inflamed colonic mucosa has not been investigated despite their important role in cellular oxidative metabolism. Using cytochemistry at the ultrastructural level, we have observed these catalase-positive organelles. In addition, biochemical analyses have revealed the specific activities of catalase and cyanide-insensitive acyl-CoA oxidase. Mucosal biopsy specimens from inflamed and noninflamed areas of Crohn's patients were compared to control biopsies. We found that Crohn's disease was marked by an important diminution in the peroxisomal frequency per cell unit area. If catalase activity was not affected by this pathology, cyanide-insensitive acyl-CoA oxidase, an enzyme of the peroxisomal beta-oxidation system, was found diminished in inflamed and in noninflamed areas. In conclusion, our results showed that Crohn's disease is accompanied by peroxisomal modifications but the number and the enzyme activities of colonic peroxisomes are less deeply altered in Crohn's disease than during neoplasia. This fact suggests that a relation may exist between the degree of peroxisomal deficiency and the clinical severity of colonic disease.

Ileal and colonic fatty acid profiles in patients with active Crohn's disease

In patients with active Crohn's disease and in a control group the fatty acid profiles in the whole lipid fraction of ileal and colonic mucosal biopsy specimens were determined by capillary gas chromatography. The biopsy specimens in Crohn's disease patients were taken from the inflamed terminal ileum as well as from the inflamed and macroscopically normal colon. Compared with controls the fatty acid distribution in the inflamed ileal mucosa was significantly characterised by (a) a decrease of 18:2 n6 and 18:3 n3 accompanied by a substantial increase of the highly polyunsaturated fatty acids 20:4 n6, 22:4 n6, and 22:6 n3 and (b) a higher unsaturation index of total fatty acids compared with controls. These changes were similar in the inflamed colon. Additionally, both the inflamed and the macroscopically normal colonic mucosa showed an increase of saturated (18:0) and a decrease of monounsaturated fatty acids (18:1 n9). Fatty acid profiles of ileum and colon showed side variations in controls, but not in the Crohn's disease group. These data suggest that in Crohn's disease changes in the distribution of polyunsaturated fatty acids seem to be the general feature of inflamed mucosa in small and large intestine. Results further suggest that colonic fatty acid metabolism in Crohn's disease is altered by degrees, showing changes in saturated and monounsaturated fatty acids as an additional, primary event.

Salicylates for ulcerative colitis--their mode of action

Delivery of 5-aminosalicylic acid to the colon by sulphasalazine, other azo-bonded compounds and controlled-release preparations is introduced in the context of metabolism by epithelial cells and therapeutic efficacy in ulcerative colitis. Potential modes of action are then reviewed, including actions on luminal bacteria, epithelial cell surface receptors, cellular events (such as nitric oxide release or butyrate oxidation), electrolyte transport and epithelial permeability. Evidence for an influence of salicylates on circulating and lamina propria inflammatory cells is presented, as well as actions on adhesion molecules, chemotactic peptides and inflammatory mediators, such as eicosanoids, platelet-activating factor, cytokines or reactive oxygen metabolites. The precise mechanism will remain uncertain as long as the aetiology of ulcerative colitis is unknown, but a pluripotential mode of action of salicylates is an advantage when influencing the network of events that constitute chronic inflammation.

Roles of leukotriene B4, prostaglandin E2, and cyclic AMP in Campylobacter jejuni-induced intestinal fluid secretion

Infection of rabbit ileal loops with inflammatory Campylobacter jejuni strains caused elevation of cyclic AMP, prostaglandin E2, and leukotriene B4 levels in tissue and fluids. Incubation of cultured Caco-2 cells with loop fluids caused elevated cellular cyclic AMP levels, an effect which was inhibited by antiserum against prostaglandin E2.

Review article: thromboxanes in inflammatory bowel disease--pathogenic and therapeutic implications

Recent work suggests that thromboxanes may play a major pathogenic role in inflammatory bowel disease. Thromboxanes are produced in excess not only in inflamed mucosa but also in Crohn's disease, by uninflamed bowel and by isolated intestinal and peripheral blood mononuclear cells. Their cellular source is likely to include platelets, neutrophils, endothelial and epithelial cells as well as mononuclear cells, possible stimuli to their overproduction being chemotactic peptides, lipopolysaccharide, leukotrienes, platelet activating factor, interleukin-1, bradykinin and angiotensin II. The pro-inflammatory effects of thromboxanes are both direct (diapedesis and activation of neutrophils, mucosal ulceration, reduction of suppressor T-cell activity) and indirect (vasoconstriction, platelet activation). Although corticosteroids and aminosalicylates inhibit thromboxane synthesis, this action does not necessarily explain their therapeutic effect in inflammatory bowel disease. Selective thromboxane synthesis inhibitors and receptor antagonists, however, ameliorate experimental colitis in animals. Picotamide and ridogrel are dual thromboxane pathway blockers already used in man. Drugs of this type could prove useful not only for the prevention of systemic thrombo-embolism but also for suppressing intestinal mucosal inflammation in patients with inflammatory bowel disease.

15-Hydroxy-eicosatetraenoic acid has minor anti-inflammatory properties in colitis

This study was performed to determine whether 15-HETE, which is the major metabolite of arachidonic acid (AA) in inflamed and normal human colonic tissue, has pro- or anti-inflammatory properties. To investigate these effects, 15-HETE (100 micrograms/kg/day) was administered rectally to mice with colitis induced by dextran sodium sulphate (DSS). Colons were removed and examined macroscopically and histologically and specimens were incubated with [14C]-AA and stimulated with A23187. Exogenous eicosanoids were separated by HPLC; the endogenously formed mediators were measured by radioimmunoassay. DSS produced a marked diffuse inflammatory response in the colon, associated with a raised inflammation score (mean 7.6 vs. < 0.5) and a significant increase in endogenously formed metabolites PGE2, LTB4 and 12-HETE. 15-HETE treatment resulted in a slight decrease in inflammation score (6.4 vs. 7.6) and a slight, but not significant, decrease in endogenous LTB4.

Inverse regulation of alpha- and beta-adrenoceptors during trinitrobenzenesulfonic acid (TNB)-induced inflammation in guinea-pig small intestine

The hypothesis has been raised that intestinal motor disturbances induced by inflammation of the digestive tract may reflect alterations in intestinal cell-membrane receptors. This question has been addressed herein for adrenoceptors by performing [3H]prazosin, [3H]rauwolscine and [3H]DHA binding studies on guinea-pig jejunal smooth-muscle membrane preparations from both healthy controls and 3, 6, and 10 days after TNB-induced intestinal inflammation. Each of the adrenoceptor subtype-selective radioligands used bound selectively to a single saturable class of sites, with no significant (p < 0.05) variation of dissociation constant (KD) values along the inflammatory process. In contrast maximal binding capacities (Bmax) for the different radioligands varied moderately but significantly (p < 0.05 and p < 0.01) according to the time after TNB injection. The alpha-adrenoceptors were significantly upregulated, respectively from (mean +/- SE in fmoles/mg of proteins) 27 +/- 3.8 (controls) to 91 +/- 3.1 (day 10) for the alpha 1-subtype, and from 26 +/- 2.7 (controls) to 102 +/- 5.9 (day 10) for the alpha 2-subtype. In contrast beta-adrenoceptors were down-regulated from 384 +/- 34.6 (controls) to 158 +/- 17.2 (day 10). These findings highlighted an apparently inverse pathological regulation of intestinal alpha- and beta- adrenoceptor densities. They suggest that changes in intestinal adrenoceptors, probably resulting from functional denervation of the inflamed bowel tissue, may contribute to the altered intestinal motility observed in inflammatory bowel diseases.

Plasma polyunsaturated fatty acid pattern in active inflammatory bowel disease

Plasma fatty acid patterns were assessed by gas liquid chromatography in 73 patients with active inflammatory bowel disease and 107 healthy controls. The influence of the disease activity on fatty acid profile was also investigated. Plasma fatty acid patterns in patients with ulcerative colitis and Crohn's disease were similar. Plasma C18:3n3 and C22:6n3 were significantly higher in active ulcerative colitis (p = 0.0143 and p < 0.00001 respectively) and in Crohn's disease (p < 0.00001 for both) than in controls, whereas C20:3n6 was significantly lower in patients than in controls, both in ulcerative colitis (p = 0.0001) and in Crohn's disease (p = 0.0041). In more severe disease, plasma polyunsaturated fatty acid concentrations fell with a significant stepwise decrease in the desaturation index (p = 0.0031 in ulcerative colitis and p = 0.0355 in Crohn's disease). Even in patients with severe disease, however, plasma n3 fatty acids (C18:3n3 and C22:6n3) never fell below those of healthy controls. These findings suggest that in active inflammatory bowel disease, an increased biosynthesis might coexist with an increased consumption of polyunsaturated fatty acids. These observations may be of relevance in the pathogenesis of the disease as polyunsaturated fatty acids are involved in tissue eicosanoid synthesis and cellular membrane function, including that of immunocompetent cells. These results also question the rationale of using n3 polyunsaturated fatty acids in the treatment of inflammatory bowel disease.

Acute-phase induction of manganese superoxide dismutase in intestinal epithelial cell lines

Cellular protection from immune-generated oxygen free radicals is initiated by the reduction of oxygen radicals by manganese superoxide dismutase (MnSOD) and copper/zinc superoxide dismutase (Cu/ZnSOD). Using rat adult (IEC-6) and fetal (IRD-98) intestinal epithelial cell lines, factors involved in the regulation of the SODs at the messenger RNA (mRNA) level were examined. Exposure of IEC-6 and IRD-98 to Escherichia coli lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNF-alpha) results in a marked increase in MnSOD mRNA as early as at 1 hour. Cotreatment of cells exposed to LPS or TNF-alpha with actinomycin D or cycloheximide showed that de novo transcription but not protein synthesis is required for the LPS- and TNF-alpha-dependent induction in MnSOD mRNA. Treatment with interleukin 1 beta results in a 12-fold increase in MnSOD mRNA, but no change was observed with interleukin 6 or interferon alpha. No change was observed in the level of Cu/ZnSOD mRNA under any condition tested. The results indicate that MnSOD functions as a cytokine-regulated acute phase protein involved in cellular protection from free radical-mediated damage.

Profuse diarrhea after misoprostol use in a patient with a history of Crohn's disease

OBJECTIVE

To report a case of profuse diarrhea after misoprostol use in a patient with a history of Crohn's disease and to discuss the role of eicosanoids in Crohn's disease.

DATA SOURCES

Patient medical records, case reports, review articles identified by MEDLINE, and personal communication with the physician, patient, and manufacturer.

DATA EXTRACTION

From interviews, the manufacturer, and pertinent published sources by one author and reviewed by the others.

DATA SYNTHESIS

A 55-year-old woman presented to clinic complaining of multiple joint pains. Her medical history was significant for peptic ulcer disease, hypertension, and Crohn's disease in remission since May 1989. Her joint pains were treated with ibuprofen 600 mg po qid and misoprostol 200 micrograms po qid (after meals and at bedtime). Following the administration of three doses of ibuprofen and misoprostol, the patient experienced abdominal cramps, pain, and voluminous, watery diarrhea for two days. Upon discontinuation of the ibuprofen and misoprostol, all of her gastrointestinal symptoms resolved within 12 hours. Rechallenge with ibuprofen alone failed to produce a recurrence of symptoms. Enhanced synthesis of intestinal eicosanoids has been demonstrated in Crohn's disease. Misoprostol, a synthetic analog of one of the eicosanoids, could induce a flare-up of Crohn's disease as suggested in this patient.

CONCLUSIONS

Misoprostol should be used with caution in patients with known inflammatory bowel disease.

Drug therapy for inflammatory bowel disease: Part II

Part II of this two-part article (See The American Journal of Surgery 1992; 164: 85-9) reviews the current definition of the role of immunosuppressive therapy in inflammatory bowel disease (IBD) and the use of antibiotics in IBD, as well as summarizes the uses of the new agents on the horizon for the treatment of IBD. Azathioprine and 6-mercaptopurine have steroid-sparing effects in patients with refractory Crohn's disease and ulcerative colitis, treat Crohn's disease-associated fistulas, and are the first agents to demonstrate efficacy in the prophylaxis of Crohn's disease. Their low risk for the development of lymphoreticular malignancy remains a factor in decisions regarding their long-term use. Cyclosporine is steroid sparing in active chronic Crohn's disease and, given intravenously, may help treat severe, refractory ulcerative colitis. Antibiotics have expanding roles: metronidazole is effective for the primary treatment of Crohn's disease, fistulas, abscess, bacterial overgrowth, and pouchitis (after ileoanal anastomosis). Other potential agents show promise in pilot studies but await controlled trials.