Marilena Fazi

Mutations of the Apc gene in experimental colorectal carcinogenesis induced by azoxymethane in F344 rats

We investigated in the rat the role of the Apc gene, which is mutated in familial adenomatous polyposis and sporadic colon cancer in the process leading from normal colonic mucosa to aberrant crypt foci (ACF) and finally to adenomas and adenocarcinomas. We analysed mutations in exon 15 of the rat Apc gene using in vitro synthesized protein assay in 66 ACF and in 28 colon tumours induced by azoxymethane. No Apc mutations were found in ACF, whereas five mutations were found in the tumours. The data suggest that mutations of the Apc gene are associated with the transition from ACF to adenoma and adenocarcinoma and not from normal mucosa to ACF.

Telocytes in Crohn's disease

Crohns disease (CD) is a relapsing chronic inflammatory disorder that may involve all the gastrointestinal tract with a prevalence of terminal ileum. Intestinal lesions have a characteristic discontinuous and segmental distribution and may affect all layers of the gut wall. Telocytes (TC), a peculiar type of stromal cells, have been recently identified in a variety of tissues and organs, including gastrointestinal tract of humans and mammals. Several roles have been proposed for TC, including mechanical support, spatial relationships with different cell types, intercellular signalling and modulation of intestinal motility. The aim of our study was to investigate the presence and distribution of TC in disease‐affected and ‐unaffected ileal specimens from CD patients compared with controls. TC were identified by CD34/PDGFRα immunohistochemistry. In affected CD specimens TC disappeared, particularly where fibrosis and architectural derangement of the intestinal wall were observed. In the thickened muscularis mucosae and submucosa, few TC entrapped in the fibrotic extracellular matrix were found. A discontinuous network of TC was present around smooth muscle bundles, ganglia and enteric strands in the altered muscularis propria. At the myenteric plexus, the loss of TC network was paralleled by the loss of interstitial cells of Cajal network. In the unaffected CD specimens, TC were preserved in their distribution. Our results suggest that in CD the loss of TC might have important pathophysiological implications contributing to the architectural derangement of the intestinal wall and gut dysmotility. Further functional studies are necessary to better clarify the role of TC loss in CD pathophysiology.

Indications and results of side-to-side isoperistaltic strictureplasty in Crohn’s disease

Purpose: Strictureplasty has commonly been used for short stenotic tracts, but it has rarely been applied to stenoses longer than 10 cm. Michelassi proposed a side-to-side isoperistaltic strictureplasty for single or multiple strictures that affected long bowel tracts. The experience and results obtained to date with this type of strictureplasty are limited. We therefore decided to review the cases in which we performed this procedure. Methods: Thirty-one patients, aged 21 to 66 years, underwent this operation between August 1996 and October 2002. Indications for surgery included subocclusion in 22 patients, malnutrition in 9 patients, and fistula or abscess in 6 patients. Two side-to-side isoperistaltic strictureplasties have been performed in jejunum, 6 in jejunum-ileum, 16 in the proximal ileum, 1 in terminal ileum, and 6 in the ileo-cecal tract. Results: The average length ofside-to-side isoperistaltic strictureplasty as 32. 1 cm (range, 10–54 cm). Sixteen patients also underwent concomitant bowel resection and 17 patients have received additional strictureplasty. There was no perioperative mortality, nor were there any postoperative complications requiring reoperation. In all patients intestinal occlusion and malnutrition were resolved. Decrease of activity indices was observed in 62. 3 percent of patients within 6 months after surgery. At an average follow-up of 26. 4 months, six patients required reoperation, but in only one of them did the recurrence involve a previous strictureplasty site. In that case the side-to-side isoperistaltic strictureplasty was soft and was without signs of inflammation or stenosis. Conclusions: Side-to-side isoperistaltic strictureplasty seems to provide a technical solution leading to improvement when long intestinal inflamed tract are treated. Longer follow-up and larger experience is needed to validate this observation.

Identification of Mucin Depleted Foci in the Human Colon

Aberrant crypt foci (ACF) originally described in rodents treated with colon-specific carcinogens have been identified also in humans at high risk of colon cancer (CRC) and are extensively used as cancer biomarkers. However, studies documenting the heterogeneity of ACF have questioned their precancerous nature. Recently, we described dysplastic foci depleted of mucins (MDF) in the colon of rats treated with colon-specific carcinogens. Like colon tumors, MDFs show activation of Wnt signaling driven by mutations in the β-catenin gene and Apc, a key gene in colorectal carcinogenesis. Because MDFs have been identified thus far only in rodents, we wanted to search for similar lesions in humans. Familial adenomatous polyposis (FAP) subjects, carrying germ-line mutations in the APC gene, are at high risk of CRC. Therefore, we first searched for MDF-like lesions in unsectioned colon samples from FAP patients and then in patients with sporadic CRC. MDFs were present in the colon of FAP patients (average of 0.0577 lesions/cm2) and at a much lower density in CRC patients (average of 0.0006 lesions/cm2). ACFs were also observed in all patients. Histologic preparations of all the MDFs identified in FAP and CRC consisted of microadenomas at variable grades of dysplasia. The occurrence of MDF-like lesions in high-risk patients provides evidence that these lesions have a counterpart in human pathology and, as observed in rodents, may represent the very early stages of CRC.

Redox State and O2•- Production in Neutrophils of Crohn's Disease Patients:

The aim of this in vitro study was to evaluate the intracellular redox state and respiratory burst (RB) in neutrophils of patients with Crohns disease (CD). The intracellular redox state and RB in neutrophils was assessed by the superoxide anion (O2•-) production induced in these cells after stimulation by various factors related to the molecular mechanisms that, if altered, may be responsible for an abnormal immune response. This can, in part, cause the onset of inflammation and tissue damage seen in CD. This study demonstrated a decreased glutathione/glutathione disulfide (GSH/GSSG) ratio index of an increased oxidative state in CD patient neutrophils. Moreover, our findings showed a decrease in tumor necrosis factor (TNF-α)- or phorbol 12-myristate 13-acetate (PMA)–induced O2•- production in CD patient neutrophils adherent to fibronectin as compared with controls. A decreased adhesion was also demonstrated. For this reason, the involvement of altered mechanisms of protein kinase C (PKC) and β-integrin activation in CD patient neutrophils is suggested. These data also showed that the harmful effects of TNF-α cannot be caused by excessive reactive oxygen species (ROS) production Induced by neutrophils. Decreased cell viability after a prolonged time of adhesion (20 hrs) was also measured in CD patient neutrophils. The findings of this study demonstrate, for the first time, that granulocyte-macrophage colony–stimulating factor (GM-CSF), a compound recently used in CD therapy, is able to activate the RB for a prolonged time both in control and CD patient neutrophils. Increased viability of CD patient neutrophils caused by GM-CSF stimulation was also observed. In conclusion, our results indicate that decreased O2•- production and adhesion, caused, in part, by an anomalous response to TNF-α, together with low GSH level and low cell viability, may be responsible for the defective neutrophil function found in CD patients. This can contribute to the chronic inflammation and relapses that characterize this pathology. A possible role of GM-CSF in inducing O2•- production and in restoring the defensive role of neutrophils in CD patients is suggested.

Beneficial effect of prolonged heme oxygenase 1 activation in a rat model of chronic heart failure

SUMMARY We and others have previously demonstrated that heme oxygenase 1 (HO-1) induction by acute hemin administration exerts cardioprotective effects. Here, we developed a rat model of heart failure to investigate whether a long-term induction of HO-1 by chronic hemin administration exerted protective effects. Sprague Dawley rats that underwent permanent ligation of the left coronary artery were closely monitored for survival rate analysis and sacrificed on day 28 post-operation. Administration of hemin (4 mg/kg body weight) every other day for 4 weeks induced a massive increase in HO-1 expression and activity, as shown by the increased levels of the two main metabolic products of heme degradation, bilirubin and carbon monoxide (CO). These effects were associated with significant improvement in survival and reduced the extension of myocardial damage. The ischemic hearts of the hemin-treated animals displayed reduced oxidative stress and apoptosis in comparison with the non-treated rats, as shown by the decreased levels of lipid peroxidation, free-radical-induced DNA damage, caspase-3 activity and Bax expression. Besides, chronic HO-1 activation suppressed the elevated levels of myeloperoxidase (MPO) activity, interleukin 1β (IL-1β) production and tumor necrosis factor-α (TNFα) production that were evoked by the ischemic injury, and increased the plasma level of the anti-inflammatory cytokine IL-10. Interestingly, HO-1 inhibitor zinc protoporphyrin IX (ZnPP-IX; 1 mg/kg) lowered bilirubin and CO concentrations to control values, thus abolishing all the cardioprotective effects of hemin. In conclusion, the results demonstrate that chronic HO-1 activation by prolonged administration of hemin improves survival and exerts protective effects in a rat model of myocardial ischemia by exerting a potent antioxidant activity and disrupting multiple levels of the apoptotic and inflammatory cascade.

Modification of azoxymethane intestinal carcinogenesis in rats by feeding sucrose boluses, pasta, and glucose

We studied whether repeated boluses of sucrose or diets containing carbohydrates with a variable glycemic index (GI) affect intestinal carcinogenesis in rats. Male F344 rats were treated twice (1 wk apart) with 15 mg/kg sc azoxymethane (AOM) and then divided into four experimental dietary groups with different carbohydrate composition and administration schedules: the sucrose group was fed 44% (wt/wt) sucrose (GI = 65), the bolus group was fed sucrose as carbohydrate and 43 boluses of sucrose (10-15 g/kg) at various time intervals, the pasta group was fed pasta [77% (wt/wt) cooked pasta, GI = 55], and the glucose group was fed 44% (wt/wt) glucose (GI = 97). All nutrients, including carbohydrates, were provided in similar amount to the different groups. The experiment was terminated between Day 230 and Day 245 after AOM administration. At this time the pasta group had significantly higher cecal short-chain fatty acids than the other groups. Intestinal adenomas and cancers occurred with the same frequency in the bolus, sucrose, and glucose groups. On the contrary, we observed a significant decrease (p = 0.03) in the cumulative incidence of intestinal adenomas, but not adenocarcinomas, in the pasta group compared with the sucrose group (intestinal adenoma incidence in the pasta group was 31% compared with 63% in the sucrose group, 46% in the bolus group, and 37% in the glucose group). In conclusion, these results do not support the hypothesis that sucrose boluses or carbohydrates with a high GI stimulate colon carcinogenesis, but they indicate that foods such as pasta may exert a protective effect.

Effect of butyrate enemas on gene expression profiles and endoscopic/histopathological scores of diverted colorectal mucosa: A randomized trial

BACKGROUND A temporary stoma is often created to protect a distal anastomosis in colorectal surgery. Short-chain fatty acids, mainly butyrate, are the major fuel source for the epithelium and their absence in the diverted tract may produce mucosal atrophy and inflammation. AIMS To investigate whether the administration of sodium butyrate enemas (Naburen(©), Promefarm, Italy) could prevent mucosal inflammation and atrophy and affect gene expression profiles after ileo/colostomy. METHODS We performed a randomized, double-blind, placebo-controlled clinical trial, in patients with enterostomy performed for inflammatory bowel disease, colorectal cancer or diverticulitis. Twenty patients were randomly allocated to receive 30ml of sodium butyrate 600mmol/L (group A) or saline (group B), b.i.d. for 30 days. RESULTS In group A endoscopic scores were significantly improved (p<0.01) while mucosal atrophy was reduced or unchanged; in group B mucosal atrophy was increased in 42.8% of patients. Despite the high dose of butyrate used, no short-chain fatty acids were detectable by gas chromatography-mass spectrometry in colorectal biopsies. Group A patients showed up-regulation of genes associated with mucosal repair such as Wnt signalling, cytoskeleton regulation and bone morphogenetic protein-antagonists. CONCLUSION Butyrate enemas may prevent the atrophy of the diverted colon/rectum, thus improving the recovery of tissue integrity.

Systemic sclerosis-like histopathological features in the myocardium of uPAR-deficient mice

Objective Cardiomyopathy is among the leading causes of death from systemic sclerosis (SSc). Urokinase-type plasminogen activator receptor (uPAR)-deficient mice have been recently reported to display important histopathological hallmarks of SSc, including dermal fibrosis, reduced dermal capillary density, and pulmonary fibrosis. Here, we investigated whether uPAR-deficient mice could display the histopathological features of SSc-related cardiomyopathy. Methods Ventricular myocardial specimens from uPAR-deficient and wild-type mice at 12 and 24 weeks of age were analysed by both light microscopy and transmission electron microscopy. Picrosirius red staining and hydroxyproline content of myocardial specimens were quantified. Myofibroblast and microvessel counts were determined by immunofluorescence for α-smooth muscle actin and CD31, respectively. Endothelial cell apoptosis was assessed by a combined TUNEL/CD31 immunofluorescence assay. Expression of uPAR in human SSc and control ventricular myocardial autopsy specimens was determined by immunohistochemistry. Results The myocardium of 24-week-old uPAR-deficient mice displayed focal ischaemic lesions with cardiomyocyte hypertrophy, myofibril rarefaction and contraction band necrosis. At 24 weeks of age, interstitial and perivascular collagen deposition and myofibroblast counts were significantly greater in myocardial tissue of uPAR-deficient mice than in wild-type mice. In uPAR-deficient mice, myocardial fibrosis was paralleled by microvascular endothelial cell apoptosis and reduced capillary density. uPAR expression was significantly downregulated in the myocardium of patients with SSc. Conclusions Typical histopathological features of SSc-related cardiomyopathy are mimicked by uPAR-deficient mice. The downregulation of uPAR in the myocardium of patients with SSc may suggest similar underlying pathogenetic mechanisms. uPAR-deficient mice could be used as a preclinical model to study the mechanisms and therapeutic approaches of myocardial involvement in SSc.

Long-term Results and Recurrence-Related Risk Factors for Crohn Disease in Patients Undergoing Side-to-Side Isoperistaltic Strictureplasty.

IMPORTANCE Side-to-side isoperistaltic strictureplasty (SSIS) is useful in patients undergoing surgery for Crohn disease (CD) to avoid wide small-bowel resections. To our knowledge, there are no definitive data regarding its recurrence risk factors. OBJECTIVE To evaluate the results obtained in a monocentric population of patients with CD who have undergone SSIS. DESIGN, SETTING, AND PARTICIPANTS From August 1996 to March 2010, 91 patients with CD underwent SSIS in our center. In this prospective observational study, side-to-side isoperistaltic strictureplasty was according the Michelassi technique in 69 patients and the Tonelli technique in 22 patients. Factors relating to the patient and the CD, surgery, and pharmacological therapy during the preoperative and perioperative periods were evaluated in association with medical or surgical recurrence. EXPOSURE Side-to-side isoperistaltic strictureplasty. MAIN OUTCOMES AND MEASURES The recurrence-free curve was estimated using Kaplan-Meier analysis. Patients were stratified into cohorts in relation to the considered categorical variables and data were compared by using the Mantel-Cox log-rank test. Cox proportional hazard regression analysis was used to set up a predictive model simultaneously exploring the effects of all independent variables on a dichotomous outcome recurrence in relation to time. RESULTS Among the 91 patients, the mean (SD) age was 39.5 (11.2) years and preoperative disease duration was 97.9 (85.8) months; 83 patients (91.2%) were followed up, of whom 37 (44.58%) experienced a recurrence at a mean (SD) of 55.46 (36.79) months after surgery (range, 9-140 months). The recurrence in the SSIS site at a mean (SD) of 48.25 (29.94) months after surgery affected 24 of 83 patients (28.9%), 9 being medical and 15 being surgical recurrence. Recurrence in the SSIS was statistically significantly associated with the time elapsed between diagnosis and surgery (P = .03). A borderline association between family history of CD and surgical recurrence (P = .054) was also found. Multivariate analysis identified the age at diagnosis (χ2 = 5.56; P = .02) and at surgery (χ2 = 7.77; P = .005), family history (χ2 = 6.26; P = .01), and smoking habit (χ2 = 10.06; P = .007) as independent risk factors for recurrence. CONCLUSIONS AND RELEVANCE In the short-term, SSIS leads to a resolution of symptoms in more than 90% of cases and the recurrence rate in the SSIS area is acceptable, even after long-term follow-up.