In vivo effects of orally administered prednisolone on prostaglandin and leucotriene production in ulcerative colitis

Fatty acids and lipid mediators in inflammatory bowel disease: from mechanism to treatment

Inflammatory Bowel Disease (IBD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract. Though the pathogenesis of IBD remains unclear, diet is increasingly recognized as a pivotal factor influencing its onset and progression. Fatty acids, essential components of dietary lipids, play diverse roles in IBD, ranging from anti-inflammatory and immune-regulatory functions to gut-microbiota modulation and barrier maintenance. Short-chain fatty acids (SCFAs), products of indigestible dietary fiber fermentation by gut microbiota, have strong anti-inflammatory properties and are seen as key protective factors against IBD. Among long-chain fatty acids, saturated fatty acids, trans fatty acids, and ω-6 polyunsaturated fatty acids exhibit pro-inflammatory effects, while oleic acid and ω-3 polyunsaturated fatty acids display anti-inflammatory actions. Lipid mediators derived from polyunsaturated fatty acids serve as bioactive molecules, influencing immune cell functions and offering both pro-inflammatory and anti-inflammatory benefits. Recent research has also highlighted the potential of medium- and very long-chain fatty acids in modulating inflammation, mucosal barriers, and gut microbiota in IBD. Given these insights, dietary intervention and supplementation with short-chain fatty acids are emerging as potential therapeutic strategies for IBD. This review elucidates the impact of various fatty acids and lipid mediators on IBD and delves into potential therapeutic avenues stemming from these compounds.

Prostaglandin E-major Urinary Metabolite as a Biomarker for Pediatric Ulcerative Colitis Activity

OBJECTIVES

Prostaglandin E-major urinary metabolite (PGE-MUM) is a useful biomarker for adult ulcerative colitis (UC) activity. In the present study, we evaluated whether PGE-MUM can also be a biomarker of pediatric UC activity and compared its efficacy in predicting UC activity with that of C-reactive protein and erythrocyte sedimentation rate.

METHODS

Twenty-nine pediatric patients with UC (8-18 years) and 29 healthy age- and sex-matched subjects were enrolled. UC activity was evaluated using the Pediatric Ulcerative Colitis Activity Index, highest Mayo endoscopic scoring (Mayo), and Matts grading (Matts) for histologic scoring, and the sum of Mayo (total of 6 segments) and Matts in all patients with UC. PGE-MUM levels were measured using a radioimmunoassay.

RESULTS

PGE-MUM levels were elevated in endoscopically and histologically active UC patients, but not in patients with endoscopic and histologic remission or controls. PGE-MUM levels positively and significantly correlated with UC activity. PGE-MUM levels were positively correlated with Pediatric Ulcerative Colitis Activity Index (r = 0.594), highest Mayo (r = 0.462), the sum of Mayo (r = 0.694), and the sum of Matts (r = 0.613), but not with highest Matt (r = 0.352). The sum of Mayo and the sum of Matts, which reflect total colon inflammation, showed highest correlation with PGE-MUM. C-reactive protein levels did not correlate with any UC activity scores. Erythrocyte sedimentation rate exhibited correlation (r = 0.490) with the sum of Mayo only.

CONCLUSIONS

PGE-MUM is a reliable biomarker that reflects both the endoscopic and histologic activity of the entire colon in pediatric UC.

Antispasmodic and myorelaxant effects of the flavoring agent methyl cinnamate in gut: potential inhibition of tyrosine kinase

Methyl cinnamate (MC) is a safe flavoring agent useful to food industry. Although chemically analog to tyrosine kinase inhibitors, there is little information regarding its biological actions. Here, we aimed at assessing the MC effects on gastrointestinal contractility and the putative involvement of tyrosine kinase in the mediation of these effects. Isometric contractions were recorded in rat isolated strips from stomach, duodenum and colon segments. In gastric strips, MC (3-3000 µM) showed antispasmodic effects against carbachol-induced contractions, which remained unchanged by either l-NAME or tetraethylammonium pretreatment and occurred with potency similar to that obtained against contractions evoked by potassium or U-46619. In colon strips, MC was four times more potent than in gastric ones. MC and the positive control genistein inhibited phasic contractions induced by acetylcholine in Ca2+-free medium, an effect fully prevented by sodium orthovanadate. Both MC and genistein decreased the spontaneous contractions of duodenal strips and shortened the time necessary for gastric fundic tissues to reach 50% of maximal relaxation. In freshly isolated colon myocytes, MC decreased the basal levels of cytoplasmic Ca2+, but not the potassium-elicited cytoplasmic Ca2+ elevation. Colon strips obtained from rats subjected to intracolonic acetic acid instillation showed reduced contractility to potassium, which was partially recovered in MC-treated rats. Inhibitory effect of nifedipine against cholinergic contractions, blunted in acetic acid-induced colitis, was also recovered in MC-treated rats. In conclusion, MC inhibited the gastrointestinal contractility with a probable involvement of tyrosine kinase pathways. In vivo, it was effective to prevent the deleterious effects of colitis resulting from acetic acid injury.

Urinary leukotriene E4 excretion: a biomarker of inflammatory bowel disease activity

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders collectively referred to as inflammatory bowel diseases (IBD). Cysteinyl leukotrienes are proinflammatory 5-lipoxygenase-derived products that play a major role in the immune and inflammatory response. Consequently, they may be involved in the pathogenesis of IBD. The aim of this study was therefore to evaluate 1) the urinary excretion of leukotriene E(4) (LTE(4)) in IBD patients and healthy volunteers, and 2) the association between LTE(4) production and the activity (relapse/remission) of the disease.

METHODS

IBD patients and healthy volunteers were prospectively recruited. CD and UC activity was determined on inclusion with the Crohn's Disease Activity Index and Clinical Activity Index, respectively. Urine was collected and the urinary excretion of LTE(4) was measured by liquid chromatography tandem mass spectrometry.

RESULTS

32 CD patients, 28 UC patients, and 30 controls were enrolled in the study. LTE(4) urinary excretion was significantly increased (P < 0.01) in CD [52.0 pg/mg creatinine (10th-90th percentiles: 26.2-148.0)] and UC [64.1 pg/mg creatinine (10th-90th percentiles: 26.7-178.0)] patients compared to controls [32.3 pg/mg creatinine (10th-90th percentiles: 21.8-58.8)]. LTE(4) levels were higher (P < 0.001) in patients with active disease than in patients in remission, for whom the levels of LTE(4) were similar to the levels of controls.

CONCLUSIONS

Cysteinyl leukotriene pathway activation could contribute to the inflammation associated with IBD. The quantification of urinary LTE(4) could be an interesting noninvasive biomarker for the assessment of IBD activity.

Colonic expression of leukotriene-pathway enzymes in inflammatory bowel diseases

BACKGROUND

Leukotrienes derived from the 5-lipoxygenase pathway are proinflammatory lipid mediators that possibly play a role in inflammatory bowel diseases. The expression of 5-lipoxygenase pathway proteins has not previously been examined in colonic mucosa in inflammatory bowel disease.

RESULTS

Quantitative immunohistochemical analyses showed that, compared to those of the control subjects (n = 9), colonic biopsies from patients with active inflammatory bowel disease (n = 17) had 3- to 7-fold higher mean counts of cells expressing 5-lipoxygenase (P = 0.03), 5-lipoxygenase-activating protein (P = 0.005), and the leukotriene A(4) hydrolase (P = 0.004), which make up the biosynthetic pathway of the potent neutrophil chemotaxin leukotriene B(4). Immunoexpression of the leukotriene C(4) synthase was unaltered (P > 0.2). The increased representation of leukotriene B(4)-pathway enzymes was associated with higher counts of neutrophils (P = 0.0001), macrophages (P = 0.03), eosinophils (P = 0.0004), CD8(+) T cells (P < 0.001), activated T cells (P < 0.05), and B cells (P < 0.05) but not of mast cells (P > 0.9). These eicosanoid and cellular changes were most marked in the subgroup of patients with ulcerative colitis (n = 9), and were absent in patients with quiescent disease (n = 6). The anomalies in the 5-lipoxygenase pathway were accompanied as expected by more cells immunostaining for cytokine-inducible COX-2 (P = 0.004, n = 17), but this study also revealed a greater number of cells expressing COX-1 in the samples from the patients in the ulcerative colitis subgroup (P = 0.03, n = 9).

CONCLUSIONS

The 5-lipoxygenase data provide a cellular basis for increased tissue synthesis of the leukotriene B(4), as reflected in the colonic mucosa and rectal dialysates of patients with active inflammatory bowel disease, which contributes to neutrophil influx and colonic injury. The COX-1/COX-2 data highlight the ambiguous functional role of prostanoid pathways in inflammatory bowel diseases.

Interleukin-1beta targets interleukin-6 in progressing dextran sulfate sodium-induced experimental colitis

Inflammatory bowel disease (IBD) is an immunologically mediated disorder that is characterized by chronic, relapsing, and inflammatory responses. Dextran sulfate sodium (DSS)-induced experimental colitis in mice has been recognized as a useful model for human IBD and interleukin (IL)-1beta is a key cytokine in the onset of IBD. The purpose of the present study was to clarify which pro-inflammatory mediators are targeted by IL-1beta in mice with DSS-induced colitis. First, we found that DSS markedly induced IL-1beta production in both dose- and time-dependent manners (P < 0.05 and P < 0.01, respectively) in murine peritoneal macrophages (pMphi), while that of tumor necrosis factor-alpha was insignificant. Further, the expressions of mRNA and protein for IL-1beta were increased in colonic mucosa and pMphi from mice that received drinking water containing 5% DSS for 7 days (P < 0.01, each). In addition, the expressions of IL-6, granulocyte macrophage-colony stimulating factor, inducible nitric oxide synthase, and cyclooxygenase-2 mRNA were also time dependently increased (P < 0.01, each). Furthermore, administration of rIL-1beta (10 microg/kg, i.p.) significantly induced the expressions of IL-1beta and IL-6 mRNA in colonic mucosa from non-treated mice (P < 0.01). Anti-mIL-1beta antibody treatments (50 microg/kg, i.p.) attenuated DSS-induced body weight reduction and shortening of the colorectum (P < 0.05, each), and abrogated the expressions of IL-1beta and IL-6 mRNA in colonic mucosa (P < 0.01, each). Our results evidently support the previous findings that IL-1beta is involved in the development of DSS-induced experimental colitis in mice, and strongly suggest that IL-1beta targets itself and IL-6 for progressing colonic inflammation.

Review article: exploration of the genetic aetiology of inflammatory bowel disease--implications for diagnosis and therapy

Genomic technologies offer new approaches to the investigation of the aetiology and pathophysiology of inflammatory bowel disease. An important field relevant to inflammatory bowel disease therapy is the pharmacogenetic investigation of gene variations that may predict responses to certain medications in order to target these therapeutic interventions more precisely. To date, only about 12,000 of the estimated 30,000-50,000 human genes have been characterized. Therefore, the use of techniques for a global analysis of gene expression may allow the identification of new pathways or molecules in the therapeutic mechanisms of drugs. Recently, NOD2 has been identified as the first disease gene in inflammatory bowel disease. DLGS and OCTN-1 have been named as further disease genes. Although the detection of disease-associated variants has greatly advanced our understanding of the primary events that lead to the development of inflammatory bowel disease in a subgroup of patients with Crohn's disease, the implications of the findings for diagnostic and therapeutic algorithms are less clear. However, it appears that there is a clear association between certain subphenotypes of Crohn's disease and the disease-associated variants in the NOD2 gene. It can be anticipated that genomic findings will profoundly influence the future therapy of inflammatory bowel disease.

Evaluation of new therapies for inflammatory bowel disease

The pathophysiology of inflammatory bowel disease (IBD) is gradually being unravelled and new therapies are being developed to target the disturbed biological processes. This article outlines the clinical features of IBD, its current therapy and pathogenesis. The difficulties for clinical pharmacologists and gastroenterologists associated with designing, executing and interpreting clinical trials in IBD are then discussed. The final section reviews methods that can used to demonstrate the pharmacological actions of new treatments in patients with IBD. It is emphasized that proof of the therapeutic efficacy of a novel agent with a specific mechanism of action yields not only clinical benefit to patients with IBD, but also indicates the importance of the targeted biochemical pathway in the pathogenesis of the disease.

Amelioration of TNBS-induced colon inflammation in rats by phospholipase A2 inhibitor

The pathophysiology of inflammatory bowel disease (IBD) involves the production of diverse lipid mediators, namely eicosanoids, lysophospholipids, and platelet-activating factor, in which phospholipase A2 (PLA2) is the key enzyme. Accordingly, it has been postulated that control of lipid mediator production by inhibition of PLA2 would be useful for the treatment of IBD. This hypothesis was tested in the present study by examining the therapeutic effect of a novel extracellular PLA2 inhibitor (ExPLI), composed of carboxymethylcellulose-linked phosphatidylethanolamine (CMPE), on trinitrobenzenesulfonic acid-induced colitis. Intraperitoneal administration of CMPE suppressed the colitis as measured by mortality rate, intestinal permeability, plasma PLA2 activity, intestinal myeloperoxidase activity, and histological morphometry. Current therapeutic approaches for inflammatory conditions focus on the selective control of a lipid mediator(s) (e.g., prostaglandins or leukotrienes). The present study supports the concept that inclusive control of lipid mediator production by PLA2 inhibition is a plausible approach to the treatment of colitis and introduces the ExPLIs as a prototype of a novel NSAID for the treatment of intestinal inflammation.

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.

Mouse colitis induced by Escherichia coli producing Yersinia enterocolitica 60-kilodalton heat-shock protein: light and electron microscope study

In patients with inflammatory bowel disease (IBD), including ulcerative colitis (UC), heat-shock protein (Hsp) 60 has been detected in serum and the intestinal tract. Our mouse colitis model was established using Escherichia coli transformed with Yersinia enterocolitica Hsp60 gene as an immunizing antigen, and examined light and electron microscopically as compared with lesions of UC. The large intestine of mice injected with Hsp60 antigen showed swollen goblet cells, glandular dilation, erosion, ulceration, and infiltration of inflammatory cells. The change like crypt abscesses was also found, and various phases of inflammation were observed simultaneously in individual mice. In addition, the reticulum fibers were absent ultrastructurally in the subepithelial reticular layer. Hyperplasia of the thymus was found in antigen-treated mice. These lesions were similar to those of UC. These results suggest that UC-like enteritis in mice was induced by using Hsp60, considered as one of the pathogens for UC.

Changes in plasma and colonic mucosa fatty acid profiles in rats with ulcerative colitis induced by trinitrobenzene sulfonic acid

Polyunsaturated fatty acids have a key role in the pathogenesis of inflammatory bowel disease since some of the arachidonic acid-derived eicosanoids have been found to be increased in inflamed intestinal mucosa in the acute phase of human disease. The aim of this study was to prospectively assess plasma and colon mucosa fatty acid patterns in rats with experimental ulcerative colitis. Twenty rats were treated with trinitrobenzene sulfonic acid and 20 with NaCl; two groups were killed after one week and two after two weeks to evaluate colon damage. Plasma was obtained by aortic puncture and colonic mucosa was scraped off and the fatty acid pattern was determined by gas-liquid chromatography. Total, saturated, and monounsaturated plasma fatty acids were significantly higher in both periods of ulcerative colitis as compared to controls. Plasma n-6 fatty acids were increased after treatment, but no significant changes were observed concerning to n-3 fatty acids. With regard to colon mucosa, saturated and monounsaturated fatty acids did not change because of the disease; however, n-6 fatty acids decreased in the first week and increased in the second week and n-3 fatty acids were increased. Changes on the fatty acid distribution in plasma did not parallel to those of colonic mucosa except for 22:6(n-3). We have also found that experimental ulcerative colitis induced by trinitrobenzene sulfonic acid reproduces many of the features related to changes in plasma and colon mucosa fatty acids observed in the human disease.

Dietary monounsaturated n-3 and n-6 long-chain polyunsaturated fatty acids affect cellular antioxidant defense system in rats with experimental ulcerative colitis induced by trinitrobenzene sulfonic acid

The intrarectal administration of trinitrobenzene sulfonic acid in rats induces ulcerative colitis, which results in histological alterations of colonic mucosa, severe modification of the cellular antioxidant defense system, and enhanced production of inflammatory eicosanoids. This study evaluated the influence of different dietary fatty acids, i.e., monounsaturated, n-3, and n-3 + n-6 polyunsaturated fatty acids, on the recovery of the colonic mucosa histological pattern, the cellular antioxidant defense system of colon, and PGE2 and LTB4 colonic mucosa contents in a model of ulcerative colitis induced by intrarectal administration of trinitrobenzene sulfonic acid. Administration of dietary n-3 polyunsaturated fatty acids led to a minimum stenosis score, a higher histological recovery, lower colon alkaline phosphatase and gamma-glutamyltranspeptidase activities, and lower mucosal levels of PGE2 and LTB4 compared with the other two experimental groups. However, glutathione transferase, glutathione reductase, glutathione peroxidase, and catalase activities were lower in the group treated with n-3 polyunsaturated fatty acids than in the groups fed with either the monounsaturated or the n-6 + n-3 polyunsaturated enriched diet. We conclude that n-3 polyunsaturated fatty acids can be administered to prevent inflammation in ulcerative colitis, but they cause a decrease in the colonic antioxidant defense system, promoting oxidative injury at the site of inflammation.

Shigella dysenteriae type 1 toxin induced lipid peroxidation in enterocytes isolated from rabbit ileum

To evaluate the role of reactive oxygen species (ROS) in Shigella dysenteriae 1 toxin (STx) mediated intestinal infection, the ligated rabbit small intestinal loops were injected with STx. The enterocytes isolated from STx treated rabbit ileal loops had a significantly higher level of lipid peroxidation as compared to enterocytes isolated from control rabbit ileum. To study the role of second messengers in STx mediated intestinal damage, the in vivo and in vitro effects of modulators of lipid peroxidation of enterocytes were used. The presence of Ca2+-ionophore A23187 enhanced the extent of lipid peroxidation in enterocytes isolated from the control and STx treated rabbit ileum. However, 1-verapamil only marginally decreased the lipid peroxidation level of enterocytes isolated from STx treated rabbit ileum. The in vitro effect of modulators was in agreement with in vivo studies. Dantrolene significantly decreased the extent of lipid peroxidation of enterocytes isolated from STx treated rabbit ileum. PMA significantly increased the lipid peroxidation level of enterocytes isolated from control ileum. However, PMA could not further enhance the lipid peroxidation level of enterocytes isolated from STx treated rabbit ileum. The presence of H-7 significantly decreased the extent of lipid peroxidation of enterocytes isolated from STx treated rabbit ileum. In vitro effect of PMA and H-7 was in agreement with that of in vivo findings. The role of arachidonic acid metabolites, prostaglandins (PGs), in mediating STx induced lipid peroxidation was also studied. The presence of indomethacin (a PG synthesis inhibitor) significantly decreased the lipid peroxidation induced by STx. These findings suggest that lipid peroxidation induced by STx is mediated through cytosolic calcium. The increase in (Ca2+)i leads to activation of PKC. A significant decrease in the enterocyte levels of antioxidant enzymes superoxide dismutase, catalase and reduced glutathione in STx treated rabbit ileum as compared to control was seen. A significant decrease in vitamin E levels was also observed. This suggests that there is decreased endogenous intestinal protection against ROS in STx mediated intestinal infection which could contribute to enterocyte membrane damage that ultimately leads to changes in membrane permeability and thus to fluid secretion.

n-3 fatty acids only delay early relapse of ulcerative colitis in remission

Relapse prevention by dietary n-3 fatty acids (5.1 g/day) was studied in a double-blind, placebo-controlled trial of 64 patients with ulcerative colitis in remission and off steroids. 5-ASA compounds were stopped three months after randomization and clinical disease activity monitored for two years. Macroscopic and histologic activity and extension was assessed by colonoscopy at entry and at exit. Both treatment groups were well matched at start. Nine patients on placebo and eight on n-3 fatty acids stopped taking their medication prematurely. Actuarial relapse-free survival was improved by n-3 fatty acids only during months 2 and 3 (2P < 0.05-0.01), but cumulative relapse rate at two years was similar for those taking placebo (18/33 = 55%) and n-3 fatty acids (18/31 = 58%). There was also no consistent difference in clinical, macroscopic, and histologic disease activity between treatment groups. The n-3 fatty acids temporarily retard, but do not prevent, relapse of ulcerative colitis.

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.

Mediators of inflammation in chronic inflammatory bowel disease

A distinguishing feature of inflammatory bowel disease (IBD) is its apparently spontaneous, chronic relapsing course. Despite extensive research over several decades the etiology of IBD remains unknown, but evidence has accumulated to suggest that the mucosal inflammatory response may be caused by (i) a defective mucosal barrier function resulting in an abnormally increased exposure to luminal antigens and toxins, (ii) an appropriate immunologic response to an unusual infection, antigen or toxin, or (iii) an inappropriate immunological response to ubiquitous antigens or stimuli. In recent years, the identification of established and potential mediators of inflammation has expanded to include eicosanoids, platelet activating factor, biogenic amines, kinins, complement-derived peptides, chemotactic peptides, cytokines, neuropeptides, and reactive metabolites of oxygen and nitrogen. Thus, the study of the inflammatory process has become ever more complex. Until the predisposing and trigger factors have been identified the achievement of a more rational and effective approach to therapy in IBD relies on interruption of the mechanisms responsible for excess mediator formation. As summarized in this review on the role of soluble mediators of inflammation, several Danish gastroenterologists have been profoundly engaged in basic and clinical research in the past 25 years to place some pieces of the confusing puzzle of IBD.

Selective blockade of leukotriene production by a single dose of the FPL 64170XX 0.5% enema in active ulcerative colitis

5-Lipoxygenase products of arachidonic acid metabolism are thought to play a central role in the secondary amplification of the inflammatory response of several inflammatory diseases, including ulcerative colitis. FPL 64170XX is a selective inhibitor of the enzyme 5-lipoxygenase. Concentrations of leukotriene B4 and prostaglanding E2 in rectal dialysis fluid from 23 males with clinically and sigmoidoscopically active, distally located ulcerative colitis were measured by radioimmunoassays in a double-blind, placebo-controlled, parallel design study before and after rectal administration of an enema containing 0.5% of FPL 64170XX. Repeated measures analysis of leukotriene B4, after adjusting for baseline, showed a significant treatment effect (P = 0.0014). The concentration of leukotriene B4 from rectal dialysates in patients receiving the active drug dropped to 15% (95% confidence interval 5-40%) of the placebo level in the second dialysis following administration of FPL 64170XX 0.5%. By contrast, prostaglanding E2 concentrations doubled (P = 0.0068) in patients receiving FPL 64170XX 0.5% with no change in the placebo group. These findings demonstrate that a single dose of FPL 64170XX 0.5% enema selectively blocks the generation of the 5-lipoxygenase product, leukotriene B4, to a mean of 85% in the target tissue of inflammation. Topical administration of this new leukotriene synthesis inhibitor may prove to be a clinically useful approach to the treatment of active, distally located ulcerative colitis.

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.

Blockade of leukotriene production by a single oral dose of MK-0591 in active ulcerative colitis

BACKGROUND

5-Lipoxygenase products of arachidonic acid metabolism are thought to play a central role in the secondary amplification of the inflammatory response in a number of human inflammatory diseases, such as ulcerative colitis. MK-0591 (3-(1((4-chlorophenyl)methyl)-3((1,1-dimethyl-ethyl)thio)-5(quinolin+ ++-2ylmethyl-oxy)-1H-indol-2yl)-2,2-dimethyl-propanoate) exerts its effect by binding to the 5-lipoxygenase activating protein, thereby inhibiting the translocation and activation of 5-lipoxygenase.

METHODS

Concentrations of leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) in rectal dialysis fluid, ex vivo biosynthesis of LTB4 in whole blood, and urinary excretion of leukotriene E4 (LTE4) from 16 patients with mild to moderately active distally located ulcerative colitis were measured by use of radioimmunoassays in a double-blind, placebo-controlled parallel-design study before and after oral administration of a 250 mg dose of MK-0591 or placebo.

RESULTS

The mean LTB4 concentration in rectal dialysis fluid was lowered after MK-0591 by > 90% (p < 0.05) from 4 to 8 hours, with a maximum inhibition of 97.5% +/- 3.4% (mean +/- SD) at 20 to 24 hours after dosing, whereas PGE2 was unchanged. In whole blood, MK-0591 decreased ex vivo biosynthesis of LTB4 (p < 0.01), with a maximum inhibition of 96.4% +/- 2.1% at 4 hours after dosing. Urinary excretion of LTE4 was reduced by more than 85% (p < 0.001) from 4 to 48 hours. No adverse events were observed.

CONCLUSION

These findings show that a single oral 250 mg dose of MK-0591 results in nearly complete blockade of systemic leukotriene production and LTB4 formation in the target tissue of inflammation (the rectum). Controlled multiple-dose trials to assess the clinical efficacy of this novel 5-lipoxygenase-activating protein inhibitor seem to be worthwhile.

Effect of leukotriene C4D4 antagonist on colonic damage induced by intracolonic administration of trinitrobenzene sulfonic acid in rats

We examined the effects of eicosanoid antagonists on colonic damage induced by trinitrobenzene sulfonic acid (TNB) in a rat inflammatory bowel model. TNB (30 mg) dissolved in 0.25 ml of 50% ethanol, was given intrarectally. The appropriate doses of ONO-1078 (a leukotriene C4D4 antagonist), ONO-4057 (a leukotriene B4 antagonist), and OKY-046 (a thromboxane A2 synthetase inhibitor) were given to obtain the same blood level, either 4 h before (pre-treatment model) or 24 h after (the post-treatment model) the administration of TNB (n = 8 in all groups). Drugs were given once daily for 6 days through a gastric feeding tube. Autopsy was performed on the 7th day. Colonic damage was assessed in terms of colonic damage scores, and myeloperoxidase (MPO) activity and eicosanoid concentrations in colonic tissues were measured. Compared with the group given TNB alone, the colonic damage score was reduced to 10% in the pre-treatment model with ONO-1078, but the score was not reduced in other groups, MPO activity was not changed in any group. The concentration of leukotriene C4 was reduced with ONO-1078 treatment, in both pre- and post-treatment models. These results demonstrated that a leukotriene C4D4 antagonist reduced colonic inflammation; however, its anti-inflammatory effect was limited in this colitis model.

Increased group II phospholipase A2 in colonic mucosa of patients with Crohn's disease and ulcerative colitis

The immunochemical protein content of group II phospholipase A2 (PLA2) and PLA2 enzymatic activity were measured for colonic mucosal biopsy samples obtained from patients with either Crohn's disease of the colon or ulcerative colitis, and control patients without inflammatory bowel disease. Immunoreactive group II PLA2 (IR-PLA2 II) content and PLA2 activity in actively inflamed colonic mucosa of Crohn's disease patients were significantly higher than those in inactively inflamed mucosa of Crohn's disease patients and the colonic mucosa of controls. IR-PLA2 II content and PLA2 activity in severely inflamed mucosa of ulcerative colitis patients were significantly higher than those in the colonic mucosa of the controls. Mucosal PLA2 enzymatic activity was closely correlated with mucosal IR-PLA2 II content in patients with Crohn's disease and ulcerative colitis. These results suggest that an increase in PLA2 enzymatic activity in inflamed colonic mucosa of Crohn's disease and ulcerative colitis was mainly attributed to increased protein content of group II PLA2, and that an increase in mucosal group II PLA2 may be involved in the pathogenesis of intestinal inflammation of Crohn's disease and ulcerative colitis.

Treatment of ulcerative colitis with high doses of oral prednisolone. The rate of remission, the need for surgery, and the effect of prolonging the treatment

Treatment of acute attacks of ulcerative colitis in 89 patients with doses of prednisolone above or equal to 40 mg resulted in an overall remission in 67%. Remission rate and colectomy rate were 47% and 42%, respectively, when the disease was severe, 80% and 13% when moderate, and 84% and 3% when mild. The need for surgery was 28% in pancolitis, 11% in left-sided colitis, and 5% in proctitis. After subsequent treatment episodes colectomy was performed in 35% of patients with pancolitis, in 37% with left-sided colitis, and in 5% with proctitis. The median total duration of therapy in patients who went into clinical remission was 4 months, and the median dose just above 3 g prednisolone. Patients who stayed in remission during the follow-up received a significantly higher start dose and total dose of prednisolone in the treatment episode than patients who had a relapse. In 25 patients treatment with doses equal to or above 75 mg of prednisolone was continued beyond 10 days, and 11 patients experienced remission whereas 14 patients had surgery performed. Orally administered corticosteroids produce results comparable to those obtained after the previously suggested intravenous regimen.

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.

A randomized controlled study of evening primrose oil and fish oil in ulcerative colitis

In a placebo-controlled study, 43 patients with stable ulcerative colitis were randomized to receive either MaxEPA (n = 16), super evening primrose oil (n = 19), or olive oil as placebo (n = 8) for 6 months, in addition to their usual treatment. Treatment with MaxEPA increased red-cell membrane concentrations of eicosapentaenoic acid (EPA) at 3 months by three-fold and at 6 months by four-fold (both P < 0.01), and doubled docosahexaenoic acid (DHA) levels at 6 months (P < 0.05). Treatment with super evening primrose oil increased red-cell membrane concentrations of dihomogamma-linolenic acid (DGLA) by 40% at 6 months (P < 0.05), whilst treatment with placebo reduced levels of DGLA and DHA at 6 months (both P < 0.05). Clinical outcome was assessed by patient diary cards, sigmoidoscopy and histology of rectal biopsy specimens. Super evening primrose oil significantly improved stool consistency compared to MaxEPA and placebo at 6 months, and this difference was maintained 3 months after treatment was discontinued (P < 0.05). There was however, no difference in stool frequency, rectal bleeding, disease relapse, sigmoidoscopic appearance or rectal histology in the three treatment groups. Despite manipulation of cell-membrane fatty acids, fish oils do not exert a therapeutic effect in ulcerative colitis, while evening primrose oil may be of some benefit.

Interleukin-2 activity of colonic lamina propria mononuclear cells in a rat model of experimental colitis

BACKGROUND

Altered interleukin 2 (IL-2) production has been implicated in the pathogenesis of inflammatory bowel diseases.

METHODS

The temporal relationship between IL-2, prostaglandin E2 (PGE2) production, and mucosal injury was evaluated by isolated colonic lamina propria mononuclear cells (LPMC), using the trinitrobenzene sulfonic acid model of rat colitis.

RESULTS

Spontaneous LPMC IL-2 activity was significantly increased in chronic (5 weeks) but not acute (5 days) or resolved colitis groups. IL-2 activity after concanavalin A activation was highest in the groups with resolved and chronic colitis. PGE2 production was significantly increased in LPMC cultures in acute or chronic colitis as well as the ethanol control groups but not the resolved colitis group. The addition of indomethacin to LPMC cultures decreased PGE2 levels in all groups, whereas IL-2 activity increased only for the chronic and resolved colitis groups. No correlation was found between PGE2 and IL-2 production by LPMC.

CONCLUSIONS

In this experimental model, LPMC IL-2 production varied according to the severity and duration of the inflammation. Increased PGE2 production does not appear to be responsible for the IL-2 alterations in colitis.

Primary colonic epithelial cell culture of the rabbit producing prostaglandins

We have established primary colonic epithelial cell culture from adult rabbits and examined effects of anti-inflammatory drugs on prostaglandin (PG) E2 production. Colonic epithelium of adult rabbits was scraped and minced into small pieces. They were incubated for isolation in Hanks' balanced salt solution with 0.35% collagenase and Earle's solution with 1 mM EDTA. Isolated cells were cultured in Coon's modified Ham's F-12 medium with 10% fetal bovine serum and antibiotics on collagen coated cell wells. The medium was refed twice a week. The production of PGs was assessed by high pressure liquid chromatography (HPLC). PGE2 and PGF2 alpha were measured by radioimmunoassay. Within 24 hours after inoculation, the cell clumps attached to the surface of the wells and cells began to spread out and grow. Monolayer cultures became confluent in 4 days. Phase contrast microscopy showed that these cells consisted of a homogeneous population of epithelial cells with large oval nuclei, polyhedral shape, and organized sheet-like growth pattern. HPLC profile showed synthesis of 6-keto-PGF1 alpha, thromboxane B2, PGF2 alpha, PGE2, and PGD2 by cultured cells. Quantitatively, 117 +/- 7 ng/mg-protein/hour PGE2 and 7.4 +/- 0.7 ng/mg-protein/hour PGF2 alpha were produced. While hydrocortisone (10(-4) - 10(-2) M) did not show a significant effect on PGE2 production, indomethacin (10(-8) - 10(-6) M), and 5-aminosalicylic acid (2X10(-4)-5X10(-3) M) inhibited PGE2 production. We have established relatively convenient procedure for primary culture of colonic epithelial cells from adult rabbits. Different actions of anti-inflammatory drugs on PGE2 synthesis suggest that these cultured cells might be a good tool for the various cellular functional studies of normal colonic epithelial cells.

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.

Effect of aminophenols (5-ASA and 4-ASA) on colonic interleukin-1 generation

The effect of 5-ASA and 4-ASA, drugs used for the treatment of inflammatory bowel disease, on modulation of experimental colitis and on colonic generation of interleukin-1 was evaluated. Three weeks of treatment with 5-ASA or 4-ASA (50 micrograms/kg) and one week of treatment with 5-ASA significantly decreased colonic interleukin-1 generation and the extent and severity of inflammation in a rat model of colitis induced by trinitrobenzene sulphonic acid. Colonic biopsies were obtained from patients with active ulcerative colitis and organ cultured 24 hours in the absence or presence of the following drugs: sulphasalazine, sulphapyridine, 5-ASA and 4-ASA (25-100 micrograms/ml). Interleukin-1 content in tissue cultured in the presence of 5-ASA (100 micrograms/ml) was two-thirds of its content in tissue cultured in drug free medium and its release into the medium was decreased by 50%. Sulphasalazine 50 micrograms/ml significantly decreased by 33% the tissue content but did not affect interleukin-1 release and a higher dose was not more effective. Sulphapyridine and 4-ASA in doses up to 100 micrograms/ml did not affect either interleukin-1 colonic content or its release into the culture medium. We conclude that pharmacological suppression of colonic interleukin-1 generation may be one, although not the sole mechanism to explain the therapeutic efficacy of 5-ASA in the treatment of inflammatory bowel disease.

Raised serum activity of phospholipase A2 immunochemically related to group II enzyme in inflammatory bowel disease: its correlation with disease activity of Crohn's disease and ulcerative colitis

Calcium dependent phospholipase A2 activity in the mixed micelles of 1-palmitoyl-2-oleoyl-phosphatidylglycerol and cholate was measured in sera of 39 patients with Crohn's disease, 40 patients with ulcerative colitis, and 40 healthy controls. The phospholipase A2 activity was significantly raised in those sera of the patients with active Crohn's disease and those with moderate and severe ulcerative colitis. The major phospholipase A2 activity derived from the sera was separated into two peaks by reverse phase high performance liquid chromatography. The phospholipase A2 active fractions were immunochemically characterised using specific antibody directed against human group II phospholipase A2 purified from rheumatoid synovial fluid. The results suggest that raised serum phospholipase A2 activity in patients with Crohn's disease and ulcerative colitis was mainly attributed to the two forms of phospholipase A2 immunochemically related to group II enzyme. In patients with Crohn's disease, serum phospholipase A2 activity decreased in parallel with clinical improvement, and correlated with serum C-reactive protein and erythrocyte sedimentation rate. The results suggest that serum phospholipase A2 activity may serve as an additional indicator of disease activity. Serum phospholipase A2 activity in patients with ulcerative colitis tends to increase in relation with endoscopic severity, and may be a more sensitive laboratory index than serum C-reactive protein and erythrocyte sedimentation rate to evaluate disease activity.

Colorectal leukotriene B4 synthesis in vitro in inflammatory bowel disease: inhibition by the selective 5-lipoxygenase inhibitor BWA4C

The in vitro synthesis of leukotriene B4 (LTB4) was evaluated in colorectal biopsy specimens and resection tissue from patients with inflammatory bowel disease. The in vitro formation of LTB4 from biopsy tissues stimulated with calcium ionophore A23187 correlated with the degree of mucosal inflammation assessed at sigmoidoscopy, and with neutrophil infiltration measured as myeloperoxidase activity. Biopsy specimens from patients taking prednisolone formed less LTB4 than those from patients not on prednisolone, with comparable levels of inflammation seen at sigmoidoscopy. The formation of LTB4 was reduced dose-dependently by the acetohydroxamic acid 5-lipoxygenase inhibitor BWA4C, with no significant inhibition of prostaglandin E2 or thromboxane B2 synthesis. In inflamed colonic resection tissue from colitic patients, the IC50 for inhibition of LTB4 formation by BWA4C was 0.03 mumol/l, compared with an IC50 of 0.8 mumol/l for NDGA. Thus, BWA4C is a potent and selective inhibitor of LTB4 synthesis in colonic tissue from patients with ulcerative colitis. Acetohydroxamic acid 5-lipoxygenase inhibitors, exemplified by BWA4C, may be useful to evaluate the clinical importance of LTB4 in ulcerative colitis, and offer a novel therapy for the disease.

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.

Incorporation of fatty acids from fish oil and olive oil into colonic mucosal lipids and effects upon eicosanoid synthesis in inflammatory bowel disease

The incorporation of the fatty acids in fish and olive oil into the colonic mucosa of patients with inflammatory bowel disease was examined during 12 weeks' dietary supplementation with the oils, and the influence on colonic mucosal prostaglandin and thromboxane generation was measured. With a dietary supplement of 18 g fish oil daily, concentrations of the major polyunsaturated fatty acids in fish oil, eicosapentaenoic acid and docosahexaenoic acid, were significantly raised in mucosal lipids. The first time these were measured, after three weeks' supplementation, the mean increases in eicosapentaenoic and docosahexaenoic acid were seven fold and 1.5 fold respectively, and these increases were maintained during the 12 week study. Arachidonic acid values fell throughout the study and this reduction was significant at 12 weeks. Mucosal prostaglandin E2 (PGE2), thromboxane B2, and 6-keto prostaglandin F1 alpha synthesis were suppressed, and this reached significance (p less than 0.05) at three and 12 weeks for PGE2 and at 12 weeks for thromboxane B2. The predominant fatty acid in olive oil is oleic acid. Supplementation with 18 g/day resulted in a significant increase in oleic acid in colonic mucosa at 12 weeks (p less than 0.05) and a fall in stearic acid and docosahexaenoic acid; there was no significant change in eicosanoid synthesis. It is concluded that colonic lipids and prostaglandin and thromboxane synthesis can be readily altered by dietary supplementation with fish oil. The extent of incorporation of the fatty acids present in oils is dependent upon the individual fatty acid.

Muscle protein synthesis in patients with rheumatoid arthritis: effect of chronic corticosteroid therapy on prostaglandin F2 alpha availability

Using stable-isotope techniques, we measured rates of quadriceps muscle protein synthesis in twelve women with sero-positive rheumatoid arthritis. The results were compared to those from the normal limb of seven women with unilateral osteoarthritis of the knee. Six patients had never received corticosteroid immuno-suppression, but the other six had taken an average of 8 mg Prednisolone per day for 9 years. Quadriceps atrophy was present in both sets of patients with rheumatoid arthritis (normal legs 444 +/- 182, rheumatoid 190 +/- 40, rheumatoid + steroid 300 +/- 110 micrograms protein/micrograms DNA, means +/- SD, both P less than 0.001). Muscle protein synthesis, calculated by comparing the incorporation of 13C-leucine into biopsy samples taken after an 8 h L-[1-13C] leucine infusion with the time averaged enrichment of blood alpha-ketoisocaproate, was 0.056 +/- 0.005% h-1 in the patients not receiving steroids compared with 0.050 +/- 0.02% h-1 in normals (P greater than 0.05) indicating that muscular atrophy was primarily due to an increase in rate of muscle protein breakdown. Intra-muscular PGE2 concentration was increased in these patients (rheumatoid 0.12 +/- 0.06 ng mg-1 tissue, normals 0.06 +/- 0.03 ng mg-1 tissue, P less than 0.05). Patients taking corticosteroids had a markedly depressed rate of muscle protein synthesis (0.035 +/- 0.008% h-1, P less than 0.05) and reduced intra-muscular PGF 2 alpha concentration (P less than 0.01). We conclude that steroid therapy significantly influences the mechanism of skeletal muscle atrophy in patients with rheumatoid arthritis.

Monocyte zinc and in vitro prostaglandin E2 and interleukin-1 beta production by cultured peripheral blood monocytes in patients with Crohn's disease

This study investigated the relationship between zinc status and prostaglandin E2 and interleukin-1 beta production by cultured monocytes in patients with Crohn's disease. Monocyte zinc was significantly decreased in both 12 inpatients and 22 outpatients compared with controls (P less than 0.001) but lymphocyte and polymorphonuclear cell zinc were normal. When cultured monocytes from 10 outpatients with Crohn's disease were stimulated with lipopolysaccharide, prostaglandin E2 production increased markedly, coupled with a fall in monocyte zinc. In matched controls, prostaglandin E2 production was significantly less and monocyte zinc remained stable. No difference in interleukin-1 release was noted between patients and controls. The addition of prednisolone to cell cultures suppressed prostaglandin E2, interleukin-1 synthesis, and monocyte zinc did not change. Zinc chloride augmented prostaglandin E2 production in patients, but not controls, and interleukin-1 remained stable. These results demonstrate a link between low monocyte zinc concentration and excessive prostaglandin production in patients with Crohn's disease.

Effect of the immune modulating agents cyclophosphamide, methotrexate, hydrocortisone, and cyclosporin A on an animal model of granulomatous bowel disease

This study was undertaken to determine the effect of cyclophosphamide, methotrexate, hydrocortisone, and cyclosporin A on a model of granulomatous infiltration in the terminal ileum and draining lymph nodes of the guinea pig. Treatment groups of six animals were used and compared to untreated groups of 12. Epithelioid cell granulomas and primary macrophage granulomas were induced by the inoculation of BCG (Pasteur) and irradiated Mycobacterium leprae respectively into the terminal ileum of the guinea pig. The response to purified protein derivative of tuberculin was reduced in both groups of animals receiving any of these agents. Cyclophosphamide and methotrexate treated animals inoculated with BCG or M leprae showed a significant reduction of granulomatous infiltration at the inoculation site (p less than 0.05 and p less than 0.001 respectively). BCG inoculated animals treated with either hydrocortisone or cyclosporin A showed no reduction in granulomatous infiltration at either the inoculation site or the draining lymph nodes. By contrast M leprae inoculated animals receiving either of these agents showed a significant reduction of granulomatous infiltration at both the inoculation site (p less than 0.001) and in the primary draining lymph node (p less than 0.001). Ziehl Neelsen staining showed an increased proportion of animals with detectable acid fast bacilli (AFB) at the inoculation site in the groups receiving hydrocortisone (50%) and methotrexate (67%) compared to untreated controls (8%). No AFB were observed in any of the animals inoculated with M leprae. In conclusion, this model may be helpful in elucidating the mechanism of T lymphocyte response in Crohn's disease and the variable clinical response seen with the use of immunosuppressive agents in this condition.

Dietary fish oil reduces progression of chronic inflammatory lesions in a rat model of granulomatous colitis

Eicosanoids are modulators of defensive and inflammatory processes in the gut mucosa, and may be involved in the pathogenesis of chronic inflammatory lesions of the bowel. As omega-3 fatty acids compete with the omega-6 as precursors of eicosanoid synthesis, we compared the effects of dietary supplementation with either sunflower (source of omega-6) or cod liver (source of omega-3) oil on the development of chronic granulomatous lesions in the rat colon. After four weeks on the supplemented diets, plasma omega-6 fatty acid content was significantly higher in the sunflower group, while omega-3 fatty acids predominated in the cod liver group. Inflammatory colitis was then induced by intracolonic administration of trinitrobenzene sulphonic acid. Luminal eicosanoid release, as measured by radioimmunoassay of intracolonic dialysis fluid, increased significantly after the challenge in both groups. Generation of prostaglandin E2 (PGE2) and leucotriene B4 (LTB4) peaked by day 3 and thereafter declined; thromboxane B2 (TXB2), instead, continued to increase from day 3 to 20 in sunflower fed rats, whereas this change was blunted in cod liver animals. The rats were killed 20, 30, or 50 days after the induction of colitis, and the colonic lesions were scored macroscopically (adhesions to surrounding tissues, strictures, ulcerations, and wall thickness) and histologically (ulceration, inflammation, depth of the lesions, and fibrosis). In cod liver animals, the damage score was markedly reduced by day 30, and inflammation and ulceration were almost absent by day 50. In conclusion, a fish oil diet prevents the increase in thromboxane in the chronic state of inflammation and shortens the course of the colonic disease by diminishing both the severity of the lesions and their progression to chronicity.

Cyclic nucleotide concentrations of rectal mucosa in ulcerative colitis

The concentrations of cyclic nucleotides (CN) were examined in rectal mucosal biopsy specimens from 52 patients with active ulcerative colitis (UC) and 10 healthy controls. The three degrees of inflammation, evaluated macroscopically by endoscopy and by morphometry in the specimens by estimating the cellular infiltration of the lamina propria, corresponded nicely with each other. The proliferative-regenerative morphologic changes in the rectal mucosa were graded qualitatively and quantitatively in three groups in accordance with defined criteria. A significant difference in cAMP concentration was only found between the most severe degree of inflammation (infiltration, 44.6%) in UC and healthy controls. cAMP concentration in rectal mucosal specimens was lower at the highest degree of regeneration than in specimens with lower degrees. Thus cAMP may play a role in the epithelial regeneration of rectal mucosa. The values of CN concentration did not correlate with the degree of inflammation in rectal mucosa from patients with UC.