M A Gassull

Effect of olive oil on early and late events of colon carcinogenesis in rats: modulation of arachidonic acid metabolism and local prostaglandin E2 synthesis

BACKGROUND Animal model studies have shown that the colon tumour promoting effect of dietary fat depends not only on the amount but on its fatty acid composition. With respect to this, the effect of n9 fatty acids, present in olive oil, on colon carcinogenesis has been scarcely investigated. AIMS To assess the effect of an n9 fat diet on precancer events, carcinoma development, and changes in mucosal fatty acid composition and prostaglandin (PG)E2 formation in male Sprague-Dawley rats with azoxymethane induced colon cancer. METHODS Rats were divided into three groups to receive isocaloric diets (5% of the energy as fat) rich in n9, n3, or n6 fat, and were administered azoxymethane subcutaneously once a week for 11 weeks at a dose rate of 7.4 mg/kg body weight. Vehicle treated groups received an equal volume of normal saline. Groups of animals were colectomised at weeks 12 and 19 after the first dose of azoxymethane or saline. Mucosal fatty acids were assessed at 12 and 19 weeks. Aberrant crypt foci and the in vivo intracolonic release of PGE2 were assessed at week 12, and tumour formation at week 19. RESULTS Rats on the n6 diet were found to have colonic aberrant crypt foci and adenocarcinomas more often than those consuming either the n9 or n3 diet. There were no differences between the rats on the n9 and n3 diets. On the other hand, administration of both n9 and n3 diets was associated with a decrease in mucosal arachidonate concentrations as compared with the n6 diet. Carcinogen treatment induced an appreciable increase in PGE2 formation in rats fed the n6 diet, but not in those fed the n3 and n9 diets. CONCLUSIONS Dietary olive oil prevented the development of aberrant crypt foci and colon carcinomas in rats, suggesting that olive oil may have chemopreventive activity against colon carcinogenesis. These effects may be partly due to modulation of arachidonic acid metabolism and local PGE2synthesis.

Cytomegalovirus infection in ulcerative colitis: A prospective, comparative study on prevalence and diagnostic strategy

Background: Cytomegalovirus (CMV) infection has been reported in ulcerative colitis (UC), especially in severe, steroid‐refractory disease. However, its role in steroid‐refractoriness remains unknown. Our goals were to evaluate the prevalence of CMV disease in UC, the best diagnostic strategy, and the influence of disease activity and/or treatment in its development. Methods: Prospective, observational study including 114 subjects with active UC requiring intravenous steroids, steroid‐refractory UC, inactive UC on mesalamine, inactive UC on azathioprine, and healthy controls. CMV antibodies, pp65‐antigenemia, and rectal biopsies for hematoxylin and eosin staining, immunohistochemistry, and CMV‐pp67 mRNA were performed. These procedures were repeated after medical treatment only in patients with active UC. CMV disease was defined by the presence of inclusion bodies and/or positive immunohistochemistry in colonic biopsies. Results: CMV disease was found in 6 steroid‐refractory, CMV‐IgG‐positive UC patients but not among controls, inactive UC, or steroid‐responding UC patients. In 5 out of the 6 patients, CMV disease was diagnosed after 7–10 days on cyclosporine. Conclusions: CMV disease in UC only affects seropositive, steroid‐refractory UC patients. Steroid/cyclosporine treatment together with disease activity may predispose to latent colonic CMV reactivation. The impact of antiviral therapy on the clinical outcome of these patients remains to be elucidated.

Bacterial translocation in cirrhotic rats. Its role in the development of spontaneous bacterial peritonitis.

Bacterial translocation occurs in ascitic cirrhotic rats, but its association with ascites infection is unknown. The aim of this study was to assess the relation between bacterial translocation and ascites infection in cirrhotic rats. Male Sprague-Dawley rats were induced to cirrhosis with intragastric CCl4. Ascitic fluid, portal and peripheral blood, mesenteric lymph nodes, liver and spleen samples were cultured before death in those cirrhotic rats with less (group A) or more (group B) than 250 polymorphonuclear neutrophils/mm3 in ascitic fluid, as well as in healthy control rats. Histological examination of jejunum, ileum, and caecum was also performed. Bacterial translocation occurred in 45% of ascitic rats (without differences between groups A and B), but in 0% controls (p = 0.01). Bacterial translocation was associated with positive ascitic fluid culture in 60% of the cases. In all of them the same bacterial species was isolated in both mesenteric lymph node and ascitic fluid. Submucosal caecal oedema (100%), ileal lymphangiectasia (41%), and caecal inflammatory infiltrate (41%) occurred in ascitic rats, the last being associated with ascitic fluid positive culture (p = 0.04). These results suggests that bacterial translocation occurs frequently in ascitic cirrhotic rats, and may play a permissive, but not unique, part in a number of ascites infections. Whether histological changes seen in cirrhotic ascitic rats favour bacterial translocation remains to be elucidated.

Serum selenium and risk of large size colorectal adenomas in a geographical area with a low selenium status

OBJECTIVE:Selenium is a fundamental nutrient to human health that might have anticarcinogenic effects. Previous studies have assessed the possible relationship of selenium status to colorectal adenomas with controversial results. We primarily aimed to assess the relationship of serum selenium status with the presence of large size colorectal adenomas in subjects living in a poor selenium region. The serum selenium status in colorectal cancer was also evaluated.METHODS:Serum selenium levels were measured in 28 patients with large size sporadic adenomatous polyps, 24 patients with colorectal adenocarcinomas, and 35 age-matched healthy individuals. A logistic regression analysis was performed to assess the relationship of serum selenium to colorectal adenomatous polyps after adjusting for confounding variables (age, sex, smoking habit, and alcohol drinking).RESULTS:Among subjects aged ≤60 yr, mean serum selenium levels were significantly lower in both patient groups (adenoma, 57.9 ± 4.3 μg/L; cancer, 43.7 ± 6.6 μg/L) than in healthy controls (88.9 ± 8 μg/L) (p = 0.0001). There were no difference among subjects >60 yr old. A significant inverse association between selenium status and the diagnosis of large size adenomatous polyps after adjusting for confounding variables was found (adjusted p = 0.029). Subjects with higher selenium status (≥75th percentile value of 82.11 μg/L) had a lower probability (OR = 0.17, 95% CI = 0.03–0.84) to be in the adenoma group than subjects with lower selenium status (<82.11 μg/L). This association was more marked in subjects aged ≤60 yr (adjusted p value = 0.04, OR = 0.08, 95% CI = 0.007–0.91), and was not significant in older subjects.CONCLUSIONS:Results suggest that high selenium status may decrease the risk of large size adenomas in a low selenium region, and that this preventive effect seems to be exclusive to subjects ≤60 yr. These results will need to be confirmed in additional epidemiological studies before recommending selenium supplementation in patients with colon adenomas.

Enteral nutrition in inflammatory bowel disease.

To assess the effect of the addition of enteral tube feeding with polymeric diets to the standard treatment of acute attacks of inflammatory bowel disease a total of 43 patients admitted to hospital (23 with Crohns disease and 20 with ulcerative colitis) were studied retrospectively. Total enteral nutrition was given to 26 as the sole nutritional supply and to 17 in conjunction with a normal ward diet, when appropriate, according to the severity of attack (control group). Nutritional state was assessed and classified in all patients at admission and at the end of the study, by measuring the triceps skinfold thickness, mid arm muscle circumference, and serum albumin concentration as representative of body fat, muscle protein, and visceral protein, respectively. At admission the three nutritional variables were not statistically different between the groups. There was a significantly positive effect on mid arm muscle circumference in patients on total enteral nutrition compared with the control group, but there was no effect on either triceps skinfold thickness or serum albumin concentration. The percentage of subjects requiring intravenous albumin infusion, however, was significantly less in the group fed enterally than in the control group. In addition, fewer patients in the group fed enterally required surgical treatment compared with the control group, despite the fact that one of the criteria for starting enteral nutritional support was the expectancy that surgery would be needed. Total enteral nutrition was well tolerated and no major side effects arose during its use in patients with acute exacerbations of inflammatory bowel disease.

Changes of the mucosal n3 and n6 fatty acid status occur early in the colorectal adenoma-carcinoma sequence.

Despite data favouring a role of dietary fat in colonic carcinogenesis, no study has focused on tissue n3 and n6 fatty acid (FA) status in human colon adenoma-carcinoma sequence. Thus, FA profile was measured in plasma phospholipids of patients with colorectal cancer (n = 22), sporadic adenoma (n = 27), and normal colon (n = 12) (control group). Additionally, mucosal FAs were assessed in both diseased and normal mucosa of cancer (n = 15) and adenoma (n = 21) patients, and from normal mucosa of controls (n = 8). There were no differences in FA profile of both plasma phospholipids and normal mucosa, between adenoma and control patients. There were considerable differences, however, in FAs between diseased and paired normal mucosa of adenoma patients, with increases of linoleic (p = 0.02), dihomogammalinolenic (p = 0.014), and eicosapentaenoic (p = 0.012) acids, and decreases of alpha linolenic (p = 0.001) and arachidonic (p = 0.02) acids in diseased mucosa. A stepwise reduction of eicosapentaenoic acid concentrations in diseased mucosa from benign adenoma to the most advanced colon cancer was seen (p = 0.009). Cancer patients showed lower alpha linolenate (p = 0.002) and higher dihomogammalinolenate (p = 0.003) in diseased than in paired normal mucosa. In conclusion changes in tissue n3 and n6 FA status might participate in the early phases of the human colorectal carcinogenesis.

Abnormal plasma polyunsaturated fatty acid pattern in non-active inflammatory bowel disease.

An abnormal plasma polyunsaturated fatty acid pattern (PUFA) (increased n3 and decreased n6 PUFA) has been reported in active inflammatory bowel disease (IBD). The possibility of a primary defect in the PUFA metabolism in IBD was hypothesised. The aim of this study was to assess plasma PUFA pattern in inactive inflammatory bowel disease and to ascertain whether patients who had had a colectomy and who were suffering from ulcerative colitis have a similar PUFA pattern than those patients with non-active ulcerative colitis and who had not had a colectomy. Plasma fatty acids were analysed by semi-capillary column gas-liquid chromatography in three groups of patients with inactive IBD (24 patients with inactive ulcerative colitis who had not had a colectomy, 15 patients with ulcerative colitis who had had a colectomy, and 27 patients with Crohns disease). Plasma concentration and percentage of C22:6n3 and unsaturation index were significantly higher in patients with inactive ulcerative colitis without a colectomy and the Crohns disease group (p < 0.0001) than in controls. Plasma concentration and percentage of C22:6n3 and the unsaturation index remained significantly higher, in both the operated and non-operated ulcerative colitis patients when compared with controls (p < 0.0001). These results suggest that in inactive IBD, an increased PUFA biosynthesis might be the cause of the high values of n3 compounds. These findings although seen in active disease, are more noticeable in remission because of the lack of artefactual factors (malnutrition, steroids, inflammation). In addition, persistence of high values in both groups of ulcerative colitis patients--that is, those who had had a colectomy and those who had not suggests the existence of a primary abnormality in the PUFA metabolism in IBD.

Infliximab safety profile and long-term applicability in inflammatory bowel disease: 9-year experience in clinical practice

Aliment Pharmacol Theru200231, 553–560

Tuberculous Chemoprophylaxis Requirements and Safety in Inflammatory Bowel Disease Patients Prior to Anti-TNF Therapy

Background: Preventive actions are advised since the use of anti‐tumor necrosis factor (TNF) agents is known to increase the risk of tuberculosis (TB). No data related to the effectiveness and safety of the preventive chemoprophylaxis (ChP) for TB in inflammatory bowel disease (IBD) patients are available. The goal was to evaluate the requirements, effectiveness, and safety profile of ChP in IBD patient candidates for anti‐TNF therapy. Methods: All IBD patients diagnosed with latent TB while evaluated for anti‐TNF therapy from the IBD database of 9 Spanish centers were included. Epidemiological and clinical data, risk factors for hepatotoxicity, ChP regimens, and side effects were registered. Results: Sixty‐three out of 497 IBD evaluated patients (12.5%) had latent TB. Sixty‐eight percent were on immunomodulators and 42% on systemic corticosteroids when a TB skin test (TST) was performed. The detection of a positive TST was done in 86% after a single exposure, but 14% needed a booster. All but 1 were treated with isoniazid alone for 6 or 9 months, and only 1 case required ChP discontinuation because of hepatotoxicity. No risk factors for hepatotoxicity were found. No cases of active TB were noticed in the 67 patients further treated with anti‐TNF therapy. Conclusions: More than 10% of Spanish IBD patients who are candidates for anti‐TNF therapy have latent TB. TST retest is required to identify at least 14% of such patients; therefore, it should be considered if the initial TST is negative. ChP is safe in IBD patients even in those taking concomitant, potentially hepatotoxic drugs.

Antineutrophil cytoplasmic antibodies in sera from colectomised ulcerative colitis patients and its relation to the presence of pouchitis.

BACKGROUND: Few studies have evaluated the influence of colectomy on antineutrophil cytoplasmic antibody (ANCA) positivity in ulcerative colitis (UC). In small series of patients it has been suggested that ANCA positivity in UC might be predictive for development of pouchitis after colectomy. AIMS: To assess the prevalence of ANCA in UC patients treated by colectomy and a Brookes ileostomy (UC-BI) or ileal pouch anal anastomosis (UC-IPAA), and the relation between the presence of ANCA, the type of surgery, and the presence of pouchitis. SUBJECTS: 63 UC patients treated by colectomy (32 with UC-BI and 31 with UC-IPAA), 54 UC, and 24 controls. METHODS: Samples were obtained at least two years after colectomy. ANCA were detected by indirect immunofluorescent assay. RESULTS: There were no differences between patients with (36.3%) or without pouchitis (35.0%) and between patients with UC (55%), UC-BI (40.6%), and UC-IPAA (35.4%). However, ANCA prevalence significantly decreases in the whole group of operated patients (38.0%) compared with non-operated UC (p = 0.044). CONCLUSIONS: The prevalence of ANCA in operated patients was significantly lower than in non-operated UC, suggesting that it might be related either to the presence of inflamed or diseased tissue. ANCA persistence is not related to the surgical procedure and it should not be used as a marker for predicting the development of pouchitis.