Role of stasis and oxidative stress in ileal pouch inflammation

Pouchitis: pathophysiology and management

Pouchitis is an acute or chronic inflammatory disease of the ileal reservoir. It is common after restorative proctocolectomy with ileal pouch-anal anastomosis, and treatment of chronic antibiotic-refractory pouchitis has proven challenging. Most cases of acute pouchitis evolve into chronic pouchitis. The aetiology of acute pouchitis is likely to be partly related to the gut microbiota, whereas the pathophysiology of chronic pouchitis involves abnormal interactions between genetic disposition, faecal stasis, the gut microbiota, dysregulated host immunity, surgical techniques, ischaemia and mesentery-related factors. Pouchoscopy with biopsy is the most valuable modality for diagnosis, disease monitoring, assessment of treatment response, dysplasia surveillance and delivery of endoscopic therapy. Triggering or risk factors, such as Clostridioides difficile infection and use of non-steroidal anti-inflammatory drugs, should be modified or eradicated. In terms of treatment, acute pouchitis usually responds to oral antibiotics, whereas chronic antibiotic-refractory pouchitis often requires induction and maintenance therapy with integrin, interleukin or tumour necrosis factor inhibitors. Chronic pouchitis with ischaemic features, fistulae or abscesses can be treated with hyperbaric oxygen therapy.

The Oxidative Stress and Nervous Distress Connection in Gastrointestinal Disorders

Oxidative stress is increasingly recognized as a central player in a range of gastrointestinal (GI) disorders, as well as complications stemming from therapeutic interventions. This article presents an overview of the mechanisms of oxidative stress in GI conditions and highlights a link between oxidative insult and disruption to the enteric nervous system (ENS), which controls GI functions. The dysfunction of the ENS is characteristic of a spectrum of disorders, including neurointestinal diseases and conditions such as inflammatory bowel disease (IBD), diabetic gastroparesis, and chemotherapy-induced GI side effects. Neurons in the ENS, while essential for normal gut function, appear particularly vulnerable to oxidative damage. Mechanistically, oxidative stress in enteric neurons can result from intrinsic nitrosative injury, mitochondrial dysfunction, or inflammation-related pathways. Although antioxidant-based therapies have shown limited efficacy, recognizing the multifaceted role of oxidative stress in GI diseases offers a promising avenue for future interventions. This comprehensive review summarizes the literature to date implicating oxidative stress as a critical player in the pathophysiology of GI disorders, with a focus on its role in ENS injury and dysfunction, and highlights opportunities for the development of targeted therapeutics for these diseases.

Nonrelaxing Pelvic Floor Dysfunction Is an Underestimated Complication of Ileal Pouch-Anal Anastomosis

BACKGROUND & AIMS

Nonrelaxing pelvic floor dysfunction (N-RPFD), or dyssynergic defecation, is the paradoxical contraction and/or impaired relaxation of pelvic floor and anal muscles during defecation. Few studies have evaluated this disorder in patients with an ileal pouch-anal anastomosis (IPAA). We investigated the frequency of N-RPFD in patients with and without chronic pouchitis following IPAA and the effectiveness of biofeedback therapy within this population.

METHODS

We conducted a retrospective study of all patients with an IPAA who underwent anorectal manometry between January 2000 and March 2015 (n = 111). N-RPFD was diagnosed in patients with symptoms consistent with a pouch evacuation disorder and 1 or more of the following abnormal tests: anorectal manometry, balloon expulsion test, barium or magnetic resonance defecography, or external anal sphincter electromyography. Patients who completed biofeedback therapy were identified and assessed to determine symptomatic response.

RESULTS

Of the 111 patients evaluated, 83 (74.8%) met criteria for N-RPFD. A significantly higher proportion of patients with chronic pouchitis were diagnosed with N-RPFD than patients without chronic pouchitis (83.3% vs 62.2%, respectively; P = .012). Most patients diagnosed with N-RPFD had abnormal results from the balloon expulsion test (78.3%); 53.0% of patients diagnosed with N-RPFD had abnormal findings from external anal sphincter electromyography, 25.3% had abnormal defecography findings, and 20.5% had abnormal findings from anorectal manometry. Twenty-two patients completed biofeedback therapy: 15 patients (68.2%) had mild-moderate improvement and 5 patients (22.7%) had significant improvement of symptoms.

CONCLUSIONS

N-RPFD occurs in almost 75% of patients with an IPAA, especially in patients with chronic pouchitis. Biofeedback seems to be an effective therapy for patients with an IPAA and N-RPFD, but further studies are needed for validation.

Review article: the pathogenesis of pouchitis

BACKGROUND

A total proctocolectomy followed by ileal pouch-anal anastomosis is a potentially curative surgery for ulcerative colitis or familial adenomatous polyposis. About 5-35% of patients with ulcerative colitis and 0-11% of patients with familial adenomatous polyposis develop subsequent inflammation of the ileal pouch termed pouchitis.

AIM

To provide a comprehensive analysis of the research studying the possible pathogenesis of pouchitis. The goals were to identify promising areas of investigation, to help focus clinicians, researchers and patients on how to better understand and then potentially manage ileal pouchitis, and to provide avenues for future research investigations.

METHODS

This review examined manuscripts from 1981 to 2015 that discussed and/or proposed hypotheses with supportive evidence for the potential underlying pathogenic mechanism for pouchitis.

RESULTS

The pathogenesis of pouchitis is not definitively understood, but various hypotheses have been proposed, including (i) recurrence of ulcerative colitis, (ii) dysbiosis of the ileal pouch microbiota, (iii) deprivation of nutritional short-chain fatty acids, (iv) mucosal ischaemia and oxygen-free radical injury, (v) host genetic susceptibility and (vi) immune dysregulation. However, none of these alone are able to fully explain pouchitis pathogenesis.

CONCLUSIONS

Pouchitis, similar to inflammatory bowel disease, is a complex disorder that is not caused by any one single factor. More likely, pouchitis occurs through a combination of both dysregulated host inflammatory mechanisms and interaction with luminal microbiota.

Stricture of ileo-anal J pouch anastomosis increased the intensity of pouchitis in an experimental rat model

Background

Pouchitis appears to be the most common complication after restorative proctocolectomy.

Material/Methods

In experimental models we investigated the correlation between the width of anastomosis and the frequency of pouchitis. Twenty-three Wistar rats underwent restorative proctocolectomy under pentobarbital anesthesia. Normal width anastomosis was performed in 11 animals (Group I). In the remaining 12 animals (Group II) the diameter of anastomosis was reduced by 50%. All animals were sacrificed and the pouch mucosa was histologically (Moskowitz score) and immunohistochemically (IL-1, IL-6, IL-10, IL-12 expression) examined.

Results

Morphological assessment of pouchitis symptoms based on Moskowitz scale revealed considerably more severe inflammation (p=0.0079) in the animals from Group II than in the rats from Group I. The expressions of investigated cytokines, assessed qualitatively in histopathological examination, were higher in rats with narrow anastomosis in comparison with animals with normal anastomosis.

Conclusions

The stricture of anastomosis increases the intensity of pouchitis and stimulates the production of interleukins. It seems that anastomotic stricture plays an important role in the development of pouchitis.

Adenocarcinomas After Prophylactic Surgery For Familial Adenomatous Polyposis

The incidence of familial adenomatous polyposis (FAP) is one in 7,000 to 12,000 live births. Virtually, all surgically untreated patients with FAP inevitably develop colorectal-cancer in their lifetime because they carry the adenomatous polyposis coli gene. Thus prophylactic proctocolectomy is indicated. Surgical treatment of FAP is still controversial. There are however, four surgical options: ileorectal anastomosis, restorative proctocolectomy with ileal pouch-anal anastomosis, proctocolectomy with ileostomy, and proctocolectomy with continent-ileostomy. Conventional proctocolectomy options largely lie between colectomy with ileorectal anastomosis or ileal pouch-anal anastomosis. Detractors of ileal pouch-anal anastomosis prefer ileorectal anastomosis because of better functional results and quality of life. The functional outcome of total colectomy with ileorectal anastomosis is undoubtedly far superior to that of the ileoanal pouch; however, the risk for rectal cancer is increased by 30%. Even after mucosectomy, inadvertent small mucosal residual islands remain. These residual islands carry the potential for the development of subsequent malignancy. We reviewed the literature (1975-2012) on the incidence, nature, and possible etiology of subsequent ileal-pouch and anal transit zone adenocarcinoma after prophylactic surgery procedure for FAP. To date there are 24 studies reporting 92 pouch-related cancers; 15 case reports, 4 prospective and 5 retrospective studies. Twenty three of 92 cancers (25%) developed in the pouch mucosa and 69 (75%) in anal transit zone (ATZ). Current recommendation for pouch surveillance and treatment are presented. Data suggest lifetime surveillance of these patients.

Probiotics in the management of inflammatory bowel disease: a systematic review of intervention studies in adult patients

INTRODUCTION

Mounting evidence suggests an important role for the intestinal microbiota in the chronic mucosal inflammation that occurs in inflammatory bowel disease (IBD), and novel molecular approaches have further identified a dysbiosis in these patients. Several mechanisms of action of probiotic products that may interfere with possible aetiological factors in IBD have been postulated.

OBJECTIVE

Our objective was to discuss the rationale for probiotics in IBD and to systematically review clinical intervention studies with probiotics in the management of IBD in adults.

METHODS

A systematic search was performed in PubMed up to 1 October 2011, using defined keywords. Only full-text papers in the English language addressing clinical outcomes in adult patients were included. The 41 eligible studies were categorized on disease type (ulcerative colitis [UC] with/without an ileo-anal pouch and Crohn's disease [CD]) and disease activity. Pooled odds ratios were only calculated per probiotic for a specific patient group when more than one randomized controlled trial was available.

RESULTS

Well designed randomized controlled trials supporting the application of probiotics in the management of IBD are still limited. Meta-analyses could only be performed for a limited number of studies revealing overall risk ratios of 2.70 (95% CI 0.47, 15.33) for inducing remission in active UC with Bifido-fermented milk versus placebo or no additive treatment (n = 2); 1.88 (95% CI 0.96, 3.67) for inducing remission in active UC with VSL#3 versus placebo (n = 2); 1.08 (95% CI 0.86, 1.37) for preventing relapses in inactive UC with Escherichia coli Nissle 1917 versus standard treatment (n = 3); 0.17 (95% CI 0.09, 0.33) for preventing relapses in inactive UC/ileo-anal pouch anastomosis (IPAA) patients with VSL#3 versus placebo; 1.21 (95% CI 0.57, 2.57) for preventing endoscopic recurrences in inactive CD with Lactobacillus rhamnosus GG versus placebo (n = 2); and 0.93 (95% CI 0.63, 1.38) for preventing endoscopic recurrences in inactive CD with Lactobacillus johnsonii versus placebo (n = 2).

CONCLUSION

Further well designed studies based on intention-to-treat analyses by several independent research groups are still warranted to support the promising results for E. coli Nissle in inactive UC and the multispecies product VSL#3 in active UC and inactive pouch patients. So far, no evidence is available to support the use of probiotics in CD. Future studies should focus on specific disease subtypes and disease location. Further insight into the aetiology of IBD and the mechanisms of probiotic strains will aid in selecting probiotic strains for specific disease entities and disease locations.

Implications of urine F2-isoprostane metabolite concentration in horses with colic and its potential use as a predictor for surgical intervention

REASONS FOR PERFORMING STUDY

F2-isoprostanes have been used extensively to quantify lipid peroxidation in association with risk factors in various diseases. Horses with colic may have intestinal ischaemia and/or inflammation characterised by oxidative stress and increased production of isoprostanes.

OBJECTIVES

To gather preliminary data regarding the feasibility of using urine F2-isoprostanes and isoprostane metabolites as early screening tools for the presence of gastrointestinal disease requiring surgical intervention in horses and ultimately develop a stall-side test capable of identifying these horses as early as possible for timely referral.

METHODS

Concentrations of urine isoprostane and isoprostane metabolite were determined by mass spectroscopy and normalised to urine creatinine (Cr) concentrations in urine samples from 42 healthy control horses and 43 horses with gastrointestinal pain or colic.

RESULTS

Horses with colic were treated medically (n = 21) or surgically (n = 22). Mean ± s.d. concentrations of urine isoprostane and isoprostane metabolite were significantly higher in horses with colic (2.94 ± 1.69 and 0.31 ± 0.22 ng/mg Cr, respectively), compared to control horses (1.89 ± 1.39 and 0.22 ± 0.08 ng/mg Cr, respectively). Mean urine isoprostane metabolite concentrations were significantly higher in horses undergoing surgery (0.38 ± 0.28 ng/mg Cr) compared to controls and medical colics (0.26 ± 0.11 ng/mg Cr). Nonsurvivors had significantly higher mean urine isoprostane metabolite concentrations (0.47 ± 0.39 ng/mg Cr) than control or surviving colic horses (0.29 ± 0.24 ng/mg Cr).

CONCLUSIONS

Measurement of urine isoprostane metabolite concentration may be a useful prognostic indicator in equine colic.

POTENTIAL RELEVANCE

Urine isoprostane metabolites may aid in early recognition of surgical colic. Isoprostanes are a potential therapeutic target to prevent further systemic and gastrointestinal tissue injury in horses with colic.

Colonic transformation of ileal pouch-anal anastomosis and of the distal ileum: MRI findings

Colonic metaplasia of the ileal reservoir in patients after ileal pouch-anal anastomosis (IPAA) is described in pathological and histochemical studies. So far, there are no reports on the imaging presentation of colonic transformation. We describe the distinctive post-operative MRI features found in a 28-year-old patient with IPAA after failed conservative treatment of chronic ulcerative colitis. These distinct MRI features of colonic transformation of ileum mimicking normal colon are important to know for radiologists reading MR examinations of patients with IPAA.

Asymmetric endoscopic inflammation of the ileal pouch: a sign of ischemic pouchitis?

BACKGROUND

Pouchitis is associated with dysbiosis and dysregulated mucosal immunity, although secondary pouchitis with special etiologic factors, such as ischemia, can occur. The aim was to describe a disease phenotype of the ileal pouch with an endoscopic appearance suggestive of ischemia.

METHODS

We identified consecutive patients with endoscopic asymmetric inflammation of the pouch (inflammation of side of the pouch with a completely normal other limb of the pouch one limb and a sharp demarcation along the staple suture line). Patients with Crohn's disease (CD) of the pouch or antibiotic-responsive pouchitis, matched for duration of the pouch, served as controls. Histology slides of mucosal biopsies were re-reviewed independently by 2 blinded gastrointestinal pathologists. Demographic, clinical, endoscopic, histologic, and imaging characteristics were compared between the groups.

RESULTS

Ten patients with "ischemic" pouchitis, 15 with CD of the pouch, and 15 with antibiotic-responsive pouchitis were studied. Pyloric gland metaplasia was observed only in the groups with CD of the pouch (23.1%) or antibiotic-responsive pouchitis (13.3%). Of patients with "ischemic" pouchitis, 80% had extracellular hemosiderin or hematoidin deposits (versus 30.8% those with CD of the pouch and 13.3% of those with pouchitis, P = 0.003). The majority of patients (80%) with "ischemic" pouchitis did not respond to conventional antibiotic therapy. It appeared that subsequent abdominal surgeries after pouch construction and a history of postoperative portal vein thrombi were associated with "ischemic" pouchitis.

CONCLUSIONS

Endoscopic asymmetric inflammation of the pouch may represent an ischemia-associated pouchitis with characteristic clinical, radiographic, and histologic features. Its hemodynamic, cellular, and molecular basis of mechanism warrants further study.

Secondary pouchitis: those with identifiable etiopathogenetic or triggering factors

Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgical treatment of choice for the majority of patients with medically refractory ulcerative colitis (UC) or UC with dysplasia, or familial adenomatous polyposis. Various forms of pouchitis frequently occur after surgery. In fact, pouchitis is the most frequent long-term complication of IPAA in patients with UC, with a cumulative prevalence of up to 50%. The etiology and pathogenesis of pouchitis are not entirely clear. It is generally believed that the initiation and development of the disease process of pouchitis is associated with dysbiosis of pouch reservoir, as evidenced by a favorable response to antibiotic therapy. However, the majority of the patients do not show identifiable etiopathogenetic or triggering factors, therefore being labeled to have idiopathic pouchitis. In contrast, a subgroup of patients, particularly those with antibiotic-refractory pouchitis, may have obvious triggering factors for disease flare-up and progression and may be considered to have secondary pouchitis. Therefore, pouchitis can be classified on the basis of etiology into idiopathic and secondary causes. Approximately 20-30% of patients who present with chronic pouchitis have secondary identifiable and triggering factors, including cytomegalovirus or Clostridium difficile infection, ischemia, concurrent immune-mediated disorders, radiation, collagen deposition, and use of nonsteroidal anti-inflammatory drugs. Careful evaluation of these secondary causes of pouchitis that may contribute to resistance to antibiotics should be performed before the introduction of next-line medical therapy.

Confocal laser endomicroscopy for the detection of mucosal changes in ileal pouch after restorative proctocolectomy

BACKGROUND

Pouchitis and dysplasia may affect the reservoir after restorative proctocolectomy.

AIMS

To assess the suitability of confocal laser endomicroscopy for the in vivo diagnosis of mucosal changes in ileal pouch for ulcerative colitis and familial adenomatous polyposis.

METHODS

Standard endoscopy and endomicroscopy were performed in 18 pouches. Confocal images were scored for the presence of villous atrophy, inflammation, ulceration, colonic metaplasia and dysplasia. Targeted biopsies were taken. Endomicroscopic and histological findings were compared.

RESULTS

At standard endoscopy, the signs of pouchitis were recorded in 7/18 (38.9%) patients. At endomicroscopy, pathological features were found in 16/18 (88.9%), villous atrophy in 15/18 (83.3%), inflammation in 13/18 (72.2%), ulceration in 3/18 (16.7%), and colonic metaplasia in 12/18 (67.7%). No dysplasia was observed. At histology, abnormalities were present in 17/18 (94.4%): villous atrophy in 15/18 (83.3%), inflammation in 17/18 (94.4%), ulceration in 6/18 (33.3%), colonic metaplasia in 15/18 (83.3%). Morphological changes of the ileal pouch could be predicted with an accuracy of 94.4% (95% CI: 74.2-99.0). The k-value for intra- and interobserver agreement was 0.93 and 0.78, respectively.

CONCLUSIONS

Endomicroscopy may be helpful in the evaluation of morphologic changes in ileal pouch. The small size of the population sample requires further studies for the results to be confirmed.

Pouchitis: lessons for inflammatory bowel disease

PURPOSE OF REVIEW

One of the significant limitations to the investigation of inflammatory bowel disease (IBD) in humans is the impossibility of studying this condition from the beginning of the disease process to understand the individual contribution of the various microbiological and immunological components to its pathogenesis. Pouchitis can serve as a human model for IBD, as the time of the pouch creation is known, which allows to prospectively study the events that might eventually lead to the development of a form of intestinal inflammation (i.e., pouchitis) that mimics IBD.

RECENT FINDINGS

A considerable amount of progress has been made in the last few years on the mechanisms underlying the pathogenesis of pouchitis. Recent literature suggests that pouchitis may present a spectrum of disease processes, with a wide range of causes, risk factors, clinical phenotypes, disease courses, and prognoses. Genetic, microbiological, and immunological profiles in pouchitis were evaluated.

SUMMARY

Ileal pouch and pouchitis represent a valuable human model to study the evolution of bacterial communities and host-bacteria interactions in IBD by sequentially monitoring microbiological and immunological profile before, during, and after pouch construction and before and after development and treatment of pouchitis.

Pouchitis: an evolving clinical enigma--a review

While the overall incidence of pouchitis is low, extensive research continues at clinical and experimental levels in attempts to unravel its etiology. The ileal pouch and pouchitis together represent a unique in vivo opportunity to study mucosal adaptation and inflammation in depth. In the recent past, molecular data relating to pouchitis has significantly expanded. These data provide invaluable insight into intracellular and extracellular events that underpin mucosal adaptation and inflammation. Advances in classification, risk factor evaluation, and prevention have meant that a review of this data, as well as its relationship to our current understanding of pouchitis, is both timely and warranted. Therefore, the aim of this review is to summarize recent data in the context of the established literature.

Portal vein thrombi after ileal pouch-anal anastomosis: its incidence and association with pouchitis

PURPOSE

Portal vein thrombi (PVT) have recently been linked to ileal pouch-anal anastomosis (IPAA). We assessed the rate of PVT in patients who underwent IPAA and attempted to identify the associated features.

METHODS

We reviewed all patients who underwent IPAA at our hospital between 1997 and 2002, noting demographic, operative, and clinical data. Computed tomography (CT) scans were independently re-reviewed by two radiologists blinded to patient data. Scans were designated as positive, negative, or indeterminate for PVT.

RESULTS

A total of 112 patients underwent IPAA for ulcerative colitis, 28 (25%) of whom had a CT scan done within 8 weeks postoperatively. The indications for CT included prolonged ileus (32.1%), abdominal pain (28.6%), and fever (17.9%). On examining the CT scans, 39% were positive, 14% were indeterminate, and 46% were negative for PVT. There was no association between PVT and pelvic sepsis. Within a mean follow-up of 36.2 months, 15.4% patients without PVT had suffered pouchitis compared with 25% of those with indeterminate scans and 45.5% of those with PVT.

CONCLUSIONS

Portal vein thrombi are a common finding in the subset of patients who require a CT scan after IPAA. Patients who suffer PVT have a higher incidence of postoperative pouchitis. Thus a prospective evaluation of the risk of PVT and its association with pouchitis is warranted.

Systematic review of dysplasia after restorative proctocolectomy for ulcerative colitis

Background

The aim of this systematic review was to assess the prevalence and site of dysplasia after restorative proctocolectomy (RPC) for ulcerative colitis (UC), and to identify risk factors that could be used in a surveillance programme.

Methods

Medical databases were searched for potentially relevant publications between 1978 and 2006. Studies that dealt with RPC for UC and postoperative surveillance were included. Two researchers independently performed study selection, quality assessment, data extraction and analysis.

Results

Twenty-three observational studies and case series were included, with a total of 2040 patients. The pooled prevalence of confirmed dysplasia in the pouch, anal transitional zone or rectal cuff was 1·13 (range 0–18·75) per cent. The prevalence of high-grade dysplasia, low-grade dysplasia and indefinite for dysplasia was 0·15 (range 0–4·49), 0·98 (range 0–15·62) and 1·23 (range 0–25·28 per cent) respectively. Dysplasia was equally frequent in the pouch and rectal cuff or anal transitional zone. Dysplasia and cancer identified before or at operation seemed to be significant predictors of the development of dysplasia. Pouchitis and duration of follow-up were not of predictive value.

Conclusion

Although based on low-level evidence from uncontrolled studies, the prevalence of dysplasia observed after RPC was remarkable. A surveillance programme that takes into account the risk factors found is therefore advocated.

A characterization of anaerobic colonization and associated mucosal adaptations in the undiseased ileal pouch

INTRODUCTION

The resolution of pouchitis with metronidazole points to an anaerobic aetiology. Pouchitis is mainly seen in patients with ulcerative colitis pouches (UCP). We have recently found that sulphate reducing bacteria (SRB), a species of strict anaerobe, colonize UCP exclusively. Herein, we aimed to correlate levels of different bacterial species (including SRB) with mucosal inflammation and morphology.

METHODS

Following ethical approval, fresh faecal samples and mucosal biopsies were taken from 9 patients with UCP and 5 patients with familial adenomatous polyposis pouches (FAPP). For the purposes of comparison, faecal samples and mucosal biopsies were also taken from the stomas of 7 of the 9 patients with UC (UCS). Colonization by four types of strict anaerobes (SRB, Clostridium perfringens, Bifidobacteria and Bacteroides) as well as by three types of facultative anaerobes (Enterococci, Coliforms and Lactobacilli) was evaluated. Inflammatory scores and mucosal morphology were assessed histologically in a blinded fashion by a pathologist.

RESULTS

In general, strict anaerobes predominated over facultative in the UCP (P = 0.041). SRB were present in UCP exclusively. Even after exclusion of SRB from total bacterial counts, strict anaerobes still predominated. In the UCS, facultative anaerobes predominated. Strict and facultative anaerobes were present at similar levels in the FAPP. Enterococci were present at significantly reduced levels in the UCP when compared with the UCS (P = 0.031). When levels of SRB and other anaerobic species were individually correlated with mucosal inflammation and morphology, no trends were observed.

CONCLUSION

We have previously identified that SRB exclusively colonize UCP. In addition we have now identified a novel increase in the strict/facultative anaerobic ratio within the UCP compared to UCS. These stark differences in bacterial colonization, however, appear to have limited impact on mucosal inflammation or morphology.

Pouchitis

Pouchitis is one of the commonest and most debilitating complications of a restorative proctocolectomy. The cause remains elusive, though a number of approaches have been shown to alleviate the condition. This review outlines current evidence relating to pouchitis, obtained from randomised and nonrandomised studies. Medline, the Bath Information Data Service (BIDS) and PubMed were searched using the keywords 'pouchitis' and 'inflammatory bowel disease'. In addition, articles were cross-referenced, and the abstracts of recent colorectal meetings studied.

A neurokinin 1 receptor antagonist reduces an ongoing ileal pouch inflammation and the response to a subsequent inflammatory stimulus

Ileal pouch-anal anastomosis (IPAA) is an excellent surgical option for patients with chronic ulcerative colitis (CUC) requiring colectomy; however, persistent episodes of ileal pouch inflammation, or pouchitis, may result in debilitating postoperative complications. Because considerable evidence implicates substance P (SP) as an inflammatory mediator of CUC, we investigated whether SP participates in the pathophysiology of pouchitis. With the use of a rat model of IPAA that we developed, we showed that ileal pouch MPO levels and neurokinin 1 receptor (NK-1R) protein expression by Western blot analysis were significantly elevated 28 days after IPAA surgery. In situ hybridization and immunohistochemistry showed that the increase in NK-1R protein expression was localized to the lamina propria and epithelia of pouch ileum. The intraperitoneal administration of the NK-1R antagonist (NK-1RA) CJ-12,255 for 4 days, starting on day 28, was effective in reducing MPO levels. Starting on day 28, animals with IPAA were given 5% dextran sulfate sodium (DSS) in their drinking water for 4 days, which caused histological and physical signs of clinical pouchitis concomitant with significant increases in ileal pouch MPO concentrations as well as NK-1R protein expression by Western blot analysis. In situ hybridization and immunohistochemistry showed that the increase in NK-1R protein expression was especially evident in crypt epithelia of pouch ileum. When the NK-1RA was administered 1 day before starting DSS and continued for the duration of DSS administration, the physical signs of clinical pouchitis and the rise in MPO were prevented. These data implicate SP in the pathophysiology of pouchitis and suggest that NK-1RA may be of therapeutic value in the management of clinical pouchitis.

Anatomic and functional characteristics of the rat ileal pouch

BACKGROUND

The definitive operation for chronic ulcerative colitis (UC) and familial adenomatous polyposis is total proctocolectomy with ileal pouch-anal anastomosis (IPAA). Mild inflammation (pouchitis) is omnipresent in pouches and becomes severe in 50% of UC patients with IPAA. The etiology of pouchitis is likely due to combined genetic, microbial, and immunologic factors. Epithelial cell exposure to surgical trauma and/or to changes in intestinal bacterial composition may account for the inflammatory infiltrate. Progress in understanding pouchitis is restricted by the lack of suitable animal models.

METHODS

An ileal pouch-rectal anastomosis [IPRA] in rats was developed to reproduce a model of human IPAA and clinical, gross and histologic criteria were determined.

RESULTS

Many shared features with human ileal pouch were observed.

CONCLUSION

IPRA is an important in vivo model to study mechanisms of repair, defense and immunity that may contribute to pouchitis.

Increased urinary F2-isoprostanes in patients with Crohn's disease

OBJECTIVES

Reactive oxygen metabolites have been suggested to participate in the pathogenesis of Crohn's disease, but the evidence supporting this contention in vivo is incomplete. Isoprostaglandin F2alpha type III (iPF2alpha-III, or 15-F2t-IsoP) is a prostaglandin F2alpha isomer produced in vivo by free radical-catalyzed peroxidation of arachidonic acid. We aimed to investigate urinary iPF2alpha-III concentrations as an index of lipid peroxidation in 23 patients with Crohn's disease compared with 23 healthy controls, and to test whether lipid peroxidation correlates to clinical relapse and inflammation.

METHODS

Urinary iPF2alpha-III was measured by gas chromatography/electronic impact mass spectrometry.

RESULTS

Urinary iPF2alpha-III concentrations were significantly higher in patients with Crohn's disease than in healthy controls (median [range] = 130 [38-622] vs 91 [35-152] pmol/mmol of creatinine, respectively; p < 0.01). There was a trend toward significance for patients with clinical relapse versus patients with clinical remission (median [range] = 155 [38-622] vs 96 [64-253] pmol/mmol of creatinine, respectively; p = 0.09). A significant correlation was found between urinary iPF2alpha-III and plasma C-reactive protein concentrations, suggesting a link between lipid peroxidation and inflammation.

CONCLUSION

This study provides evidence of increased lipid peroxidation in patients suffering from Crohn's disease, especially in patients with clinical relapse. iPF2alpha-III quantification has to be investigated as a prognosis biomarker in patients suffering from Crohn's disease.

Pouchitis in a rat model of ileal J pouch-anal anastomosis

Endorectal ileal pouch-anal anastomosis (IPAA) has become the operation of choice for patients with chronic ulcerative colitis. Although this procedure improves the quality of life, pouchitis remains a significant postoperative complication. Because our understanding of the pathophysiology of pouchitis may, in part, be due to the lack of small animal model, our aim was to develop a model of IPAA in a rat that mimics its clinical counterpart. Colectomy, proctectomy, construction of an ileal J pouch, and ileal pouch-rectal anastomosis as a model of IPAA was performed in Sprague-Dawley and Lewis rats. Radiographic contrast studies were performed to quantitate intestinal transit. The presence of activated neutrophils was quantified by measuring mucosal myeloperoxidase (MPO) activity. Oxidative stress was quantitated by measuring urinary 8-isoprostane (8-IP) levels. Anaerobic and aerobic bacterial counts were determined on Brucella and tryptic soy agar plates, respectively. Dextran sulfate sodium (DSS) was used to exacerbate ileal J pouch inflammation. Mortality was low, and animals gained weight normally after recovery. Stasis was documented radiographically. MPO levels were elevated (p < 0.05) in the ileal J pouch 30 and 60 days after IPAA, indicating an inflammation that was associated with stasis and bacterial overgrowth. 8-IP levels were elevated by 80% compared with controls. Oral administration of 5% DSS to IPAA rats with further elevated MPO and 8-IP levels in concert with a pouchitis-like syndrome that included the physical, gross, and histologic characteristics of clinical pouchitis. An understanding of the pathophysiology of pouchitis is essential to the future development of new therapeutic modalities. This model is applicable to investigating several key etiologic mechanisms purportedly related to pouchitis.

Surgery of the small bowel

This review deals with various developments in the field of small-bowel surgery, including the role of ileal pouch-anal anastomosis and ileorectal anastomosis in the treatment of ulcerative colitis and familial adenomatous polyposis. We discuss modern trends in the surgical management of Crohn disease, and the increasing use of laparoscopy in the management of inflammatory bowel disease and small-bowel obstruction. In addition to looking at small-bowel tumors, this review deals with the current status of small-bowel transplantation.