Intestinal permeability in the ileal pouch

Normal Ileal Mucus Is Inadequate for Epithelial Protection in Ileal Pouch Mucosa

BACKGROUND

Clinical, nonspecific pouchitis is common after restorative proctocolectomy for ulcerative colitis, but its cause is unknown. A possible lack of protection for the ileal mucosa in its role as a reservoir for colonic-type bacteria may be the missing piece in defining the causes of pouchitis.

OBJECTIVE

The study aimed to review the causes of pouchitis and introduce the hypothesis that inadequate mucus protection in the pouch, combined with a predisposition to abnormal inflammation, is the most common cause of nonspecific pouchitis.

DATA SOURCES

Review of PubMed and MEDLINE for articles discussing pouchitis and intestinal mucus.

STUDY SELECTION

Studies published from 1960 to 2023. The main search terms were "pouchitis," and "intestinal mucus," whereas Boolean operators were used with multiple other terms to refine the search. Duplicates and case reports were excluded.

MAIN OUTCOME MEASURES

Current theories about the cause of pouchitis, descriptions of the role of mucus in the physiology of intestinal protection, and evidence of the effects of lack of mucus on mucosal inflammation.

RESULTS

The crossreference of "intestinal mucus" with "pouchitis" produced 9 references, none of which discussed the role of mucus in the development of pouchitis. Crossing "intestinal mucus" with "pouch" resulted in 32 articles, combining "pouchitis" with "barrier function" yielded 37 articles, and "pouchitis" with "permeability" yielded only 8 articles. No article discussed the mucus coat as a barrier to bacterial invasion of the epithelium or mentioned inadequate mucus as a factor in pouchitis. However, an ileal pouch produces a colonic environment in the small bowel, and the ileum lacks the mucus protection needed for this sort of environment. This predisposes pouch mucosa to bacterial invasion and chronic microscopic inflammation that may promote clinical pouchitis in patients prone to an autoimmune response.

LIMITATIONS

No prior studies address inadequate mucus protection and the origin of proctitis. There is no objective way of measuring the autoimmune tendency in patients with ulcerative colitis.

CONCLUSIONS

Studies of intestinal mucus in the ileal pouch and its association with pouchitis are warranted.

A New Rat Model of Pouchitis After Proctocolectomy and Ileal Pouch-Anal Anastomosis Using 2,4,6-Trinitrobenzene Sulfonic Acid

BACKGROUND

Pouchitis is a common complication after ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis. However, an ideal model remains lacking. Therefore, we aimed to establish an appropriate model resembling human pouchitis.

METHODS

Sprague-Dawley rats were randomly assigned to five groups: TNBS group, DSS group, NS group (following IPAA procedure, administrated with TNBS enema, DSS orally, normal saline enema, respectively), NI group (underwent IPAA), and sham group (underwent switch abdominal surgery). General status, weight change, hematochezia, and fecal scores were recorded. Fecal microbiota were counted under a microscope and analyzed by 16S rRNA gene high-throughput sequencing. Specimens of ileal pouch and small intestine (proximal, mid, distal) were collected to evaluate myeloperoxidase and occludin expression by immunohistochemistry and mRNA expression of pro-inflammatory markers by PCR.

RESULTS

General status, hematochezia, fecal score, and increased mRNA expression of interleukin-6 and TNF-α in the TNBS group were similar to those in the DSS group, whereas the TNBS-induced model displayed a more stable weight change and more serious dysbacteriosis, not only was fecal bacterial diversity reduced, the dominant microbiota was altered. Histopathology scores of the distal small intestine in the TNBS group were lower compared with those in the DSS group (P < 0.05). A significant difference in myeloperoxidase and occludin expression in the small intestine was also detected between the TNBS and DSS groups.

CONCLUSIONS

Our model mimicked the characteristics of human pouchitis and avoided potential side effects in the small intestine, and thus could be employed for further research.

Prevention and Medical Treatment of Pouchitis In Ulcerative Colitis

Approximately 50% of patients who have undergone IPAA surgery for Ulcerative Colitis (UC) develop at least 1 episode of pouchitis. Patients with pouchitis have a wide range of symptoms, endoscopic and histologic features, disease course, and prognosis. To date, there are no universally accepted diagnostic criteria in terms of endoscopy and histology; though, semi-objective assessments to diagnose pouchitis in patients with ileal pouch- anal anastomosis (IPAA) have been proposed using composite scores such as the Pouchitis Triad, Heidelberg Pouchitis Activity Score and Pouchitis Disease Activity Index (PDAI). In a systematic review that included four randomized trials evaluating five agents for the treatment of acute pouchitis, ciprofloxacin was more effective at inducing remission as compared with metronidazole. Rifaximin was not more effective than placebo, while budesonide enemas and metronidazole were similarly effective for inducing remission of acute pouchitis. Patients with pouchitis relapsing more than three times per year are advised maintenance therapy, and guidelines recommend ciprofloxacin or the probiotic VSL#3. In patients with antibiotic-refractory pouchitis, secondary factors associated with an antibiotic-refractory course should be sought and treated. In this review, we will discuss the prevention and management of pouchitis in Ulcerative Colitis patients.

Innate immune factors in the development and maintenance of pouchitis

BACKGROUND

Tight junction proteins (TJPs) and dendritic cells (DC) are critical in the pathogenesis of inflammatory bowel diseases. The ileal pouch formed by restorative proctocolectomy provides a unique human model for studying the pathogenesis of inflammatory bowel diseases. Data implicate the microbiota in the pathogenesis of pouchitis, while the role of innate immune factors remains unclear. We performed longitudinal and cross-sectional studies of patients after restorative proctocolectomy and assessed TJP and DC characteristics in the ileal pouch.

METHODS

Mucosal biopsies were taken from the ileal pouch of patients with ulcerative colitis (UC) and familial adenomatous polyposis (n = 8). Of patients with UC, one group (n = 5) was followed longitudinally over the first year after ileostomy closure, another group had pouchitis (n = 15), and another group no inflammation (n = 18). Dendritic cell phenotype and epithelial cell TJP expression were assessed using flow cytometric analysis.

RESULTS

Increased epithelial expression of the "pore-forming" TJP claudin 2, and DC expression of gut-homing markers CCR 9 and integrin β7, occurred early after ileostomy closure. In patients with UC with pouchitis, epithelial expression of ZO-1 and claudin 1 were reduced, DC were activated with increased CD40, and Toll-like receptor 4 expression increased. In pouchitis, DC expressing CCR 9 were decreased, whereas DC expressing β7 increased.

CONCLUSIONS

Abnormalities were found in TJP expression in the pouch of patients with UC, in particular, increased expression of the pore-forming claudin 2 as an early event in the development of pouch inflammation and an aberrant DC phenotype was characterized in the ileal pouch of patients with UC.

Colonic phenotype of the ileum in Crohn's disease: a prospective study before and after ileocolonic resection

BACKGROUND

Colonic metaplasia has been described in pouchitis. In a prospective study, we investigated whether colonic phenotype may develop in Crohn's disease (CD) ileum. The expression of sulfomucins (colonic mucin), sialomucins, and CD10 (small intestine mucin and phenotype) was evaluated before and after ileocolonic resection for CD.

METHODS

From February 2007 to March 2010, 22 patients with CD undergoing surgery were enrolled. Clinical (Crohn's Disease Activity Index >150) and endoscopic recurrence (Rutgeerts score ≥1) rates were assessed at 6 and 12 months. Ileal samples were taken at surgery (T0), at 6 (T1), and 12 months (T2) for histology, histochemistry (High Iron Diamine-Alcian Blue), and immunohistochemistry (anti-CD10).

RESULTS

In 22 patients, recurrence was assessed at 6 and 12 months (clinical recurrence 9% and 18%; endoscopic recurrence 73% and 77%). In all 22 patients, ileal samples were taken at 6 and 12 months (involved area in patients with recurrence). In 19 of 22 (86.3%) patients, the involved ileum was also studied at surgery. At T0, T1, and T2, the expression of sialomucins and CD10 (small intestine mucin and phenotype) was comparable and higher (P < 0.0001) than the expression of sulfomucins (colonic mucin) (mean [range], T0:82 [35-100] versus 75 [0-100] versus 16 [0-50]; T1:96 [60-100] versus 94.7 [50-100] versus 3.89 [0-40]; T2:93.3 [60-100] versus 88.1 [25-100] versus 6.6 [0-40]). The expression of small-intestine mucin and phenotype was higher at T1 (P = 0.025) versus T0 (P = 0.026). Differently, the expression of colonic mucin was lower at T1 versus T0 (P = 0.027).

CONCLUSIONS

In CD, the ileum involved by severe/established lesions develops a "metaplastic" colonic mucosa phenotype. Differently, CD ileum with no lesions or with early recurrence maintains the "native" small intestine type mucin secretion and phenotype.

Pouchitis: what every gastroenterologist needs to know

Pouchitis is the most common complication among patients with ulcerative colitis who have undergone restorative proctocolectomy with ileal pouch-anal anastomosis. Pouchitis is actually a spectrum of diseases that vary in etiology, pathogenesis, phenotype, and clinical course. Although initial acute episodes typically respond to antibiotic therapy, patients can become dependent on antibiotics or develop refractory disease. Many factors contribute to the course of refractory pouchitis, such as the use of nonsteroidal anti-inflammatory drugs, infection with Clostridium difficile, pouch ischemia, or concurrent immune-mediated disorders. Identification of these secondary factors can help direct therapy.

Etiology of pouchitis

Restorative proctocolectomy with ileal-pouch anal anastomosis (RPC) is the operation of choice for ulcerative colitis (UC) patients requiring surgery. It is also used for patients with familial adenomatous polyposis (FAP). Pouchitis accounts for 10% of pouch failures. It is an idiopathic inflammatory condition that may occur in up to 50% of patients after RPC for UC. It is rarely seen in FAP patients after RPC. The etiology of pouchitis remains unclear. An overlap with UC is suggested by the frequency with which pouchitis affects patients with UC compared with FAP patients. There is significant clinical evidence implicating bacteria in the pathogenesis of pouchitis. Studies using culture and molecular methods demonstrate a dysbiosis of the pouch microbiota in pouchitis. Risk factors, genetic associations, and serological markers of pouchitis suggest that the interactions between the host immune responses and the pouch microbiota underlie the etiology of this idiopathic inflammatory condition. Here we present a detailed review of the data focusing on the pouch microbiota and the immune responses that support this hypothesis. We also discuss the contribution of luminal metabolic factors and the epithelial membrane in the etiology of this inflammatory process. The ileoanal pouch offers a unique opportunity to study the inter-relationships between the gut microbiota and host immune responses from before the onset of disease. For this reason the study of pouchitis could serve as a human model that significantly enhances our understanding of inflammatory bowel diseases in general.

Acute and chronic pouchitis--pathogenesis, diagnosis and treatment

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the procedure of choice for the majority of patients with ulcerative colitis who require surgical treatment. Pouchitis, the most common long-term complication of the procedure, involves a spectrum of disease processes with heterogeneous risk factors, clinical features, disease courses and prognoses. In addition, clinical symptoms of pouchitis are not specific and often overlap with those of other inflammatory and functional pouch disorders, such as Crohn's disease of the pouch and irritable pouch syndrome. Pouchoscopy and biopsy, along with laboratory and radiographic evaluations, are often required for accurate diagnosis in patients with symptoms indicative of pouchitis. Dysbiosis has been implicated as a triggering factor for pouchitis, and concurrent infection with pathogens, such as Clostridium difficile, might contribute to disease relapse and exacerbation. Antibiotic therapy is the main treatment modality. However, the management of antibiotic-dependent and antibiotic-refractory pouchitis remains challenging. Secondary causes of pouchitis, such as ischaemia, NSAID use, the presence of concurrent primary sclerosing cholangitis and other systemic immune-mediated disorders, should be evaluated and properly managed.

Clinical implication of false-positive celiac serology in patients with ileal pouch

BACKGROUND

In patients with symptoms of pouchitis retractable to antibiotic therapy, serology is often ordered to exclude concurrent celiac disease. The clinical utility of celiac serology in patients with ileal pouches is unknown. The aim of this study was to investigate the clinical implications of false-positive celiac serology in patients with ileal pouches.

METHODS

All patients with pouches who had underlying ulcerative colitis and available celiac serology were included from the subspecialty Pouchitis Clinic at the Cleveland Clinic between 2002 and 2007. Chronic antibiotic-refractory pouchitis was diagnosed based on persistent symptomatic pouchitis after a 4-week single- or dual-antibiotic therapy.

RESULTS

A total of 126 patients were studied, and a false-positive celiac serology was observed in 19 patients. Chronic antibiotic-refractory pouchitis was diagnosed in 47% (9/19) of patients with false-positive celiac serology compared with 14% (15/107) of patients with a negative celiac serology (P = .003). In multivariate analysis, the association between false-positive celiac serology and chronic antibiotic-refractory pouchitis remained significant (odds ratio, 5.4; 95% confidence interval, 1.7-16.7; P = .004) after adjusting for sex (P = .03), pouch duration (P = .83), the presence of autoimmune disorders (P = .46), and extraintestinal manifestations (P = .63).

CONCLUSION

False-positive celiac serology appeared to be common in patients with ileal pouch-anal anastomosis and it may be associated with chronic antibiotic-refractory pouchitis.

Pouchitis and pouch dysfunction

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the surgical treatment of choice for most patients with ulcerative colitis who require surgery. Although the surgical procedure offers a cure in some patients, postoperative inflammatory and noninflammatory complications are common. Pouchitis is the most common long-term complication of the procedure. Pouchitis represents a spectrum of disease processes with heterogeneous risk factors, clinical phenotypes, natural history, and prognosis. Accurate diagnosis and classification are important for proper treatment and prognosis.

Pouchitis and pouch dysfunction

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the surgical treatment of choice for most patients with ulcerative colitis who require surgery. Although the surgical procedure offers a cure in some patients, postoperative inflammatory and noninflammatory complications are common. Pouchitis is the most common long-term complication of the procedure. Pouchitis represents a spectrum of disease processes with heterogeneous risk factors, clinical phenotypes, natural history, and prognosis. Accurate diagnosis and classification are important for proper treatment and prognosis.

Inflamed pouch mucosa possesses altered tight junctions indicating recurrence of inflammatory bowel disease

BACKGROUND AND AIMS

The etiology of pouchitis after coloproctomucosectomy with ileal pouch-anal anastomosis in patients with ulcerative colitis is still unknown. Beside changes in luminal antigens, the immunological predisposition is assumed to be responsible. In previous electrophysiological studies, we showed that mucosal barrier and transport function in pouchitis is markedly reduced. Thus, the aim of the present study was to analyze barrier function on the molecular level.

MATERIAL AND METHODS

Pouch biopsies of 36 ulcerative colitis patients were analyzed. Time points were (1) intraoperative immediately prior to ileal pouch-anal anastomosis (n = 13), (2) >1 year after ileostomy closure (pouch, n = 12), and (3) during pouchitis (n = 11). Control terminal ileum biopsies were obtained from eight patients undergoing hemicolectomy due to carcinoma. Expression of tight junction proteins was analyzed by Western blotting and confocal laser-scanning microscopy. To elucidate effects on epithelial barrier properties, impedance spectroscopy was performed in miniaturized Ussing chambers.

RESULTS

In pouchitis, epithelial resistance was markedly reduced compared to non-inflamed pouch and control ileum. Expression of tight junction proteins claudin-1, 3, 4, 5, and 7 and occludin revealed differential expression regulation with the tightening tight junction protein claudin-1 being decreased and an increase of the pore-forming claudin-2, whereas other claudins remained constant. Morphometry indicated the mucosal surface to be unchanged.

CONCLUSION

Pouchitis is characterized by a selective change of tight junction proteins in favor of opening the epithelial tight junction and, thus, the paracellular pathway, which contributes to the inflammatory process. This resembles changes in inflammatory bowel disease (IBD) and indicates IBD recurrence in pouchitis.

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.

Pathogenesis of and unifying hypothesis for idiopathic pouchitis

Ileal pouch-anal anastomosis is the procedure of choice in the surgical management of refractory ulcerative colitis. Pouchitis affects up to 60% of patients following ileal pouch-anal anastomosis for ulcerative colitis. It overlaps significantly with ulcerative colitis such that improvements in our understanding of one will impact considerably on the other. The symptoms are distressing and impinge significantly on patients' quality of life. Despite 30 years of scientific and clinical investigation, the pathogenesis of pouchitis is unknown; however, recent advances in molecular and cell biology make a synergistic hypothesis possible. This hypothesis links interaction between epithelial metaplasia, changes in luminal bacteria (in particular sulfate-reducing bacteria), and altered mucosal immunity. Specifically, colonic metaplasia supports colonization by sulfate-reducing bacteria that produce hydrogen sulfide. This causes mucosal depletion and subsequent inflammation. Although in most cases antibiotics lead to bacterial clearance and symptom resolution, immunogenetic subpopulations can develop a chronic refractory variant of pouchitis. The aims of this paper are to discuss proposed pathogenic mechanisms and to describe a novel mechanism that combines many hypotheses and explains several aspects of pouchitis. The implications for the management of both pouchitis and ulcerative colitis are discussed.

Association between immune-associated disorders and adverse outcomes of ileal pouch-anal anastomosis

OBJECTIVES

Autoimmune disorders (ADs) frequently coexist with inflammatory bowel disease. The aim of the study was to determine whether coexisting AD in patients with ileal pouches increases the risk for chronic antibiotic-refractory pouchitis (CARP) and other inflammatory conditions of the pouch.

METHODS

A total of 622 patients seen in our Pouchitis Clinic were enrolled. We compared the prevalence of adverse outcomes of the pouch (including CARP, Crohn's disease of the pouch, and pouch failure) in patients with or without concurrent AD and assessed the factors for these adverse outcomes.

RESULTS

There were seven pouch disease categories: normal (N=60), irritable pouch syndrome (N=112), active pouchitis (N=131), CARP (N=67), Crohn's disease (N=131), cuffitis (N=83), surgical complications (N=36), and anismus (N=2). The prevalence of AD in these pouch disease categories was 4.5%, 12.5%, 9.2%, 13.4%, 10.7%, 3.8%, 1.5%, and 0%, respectively. The presence of at least one AD at time of pouch surgery was shown to be associated with a twofold increase in the risk for CARP (hazard ratio=2.29; 95% CI: 1.52, 3.46; P<0.001) and for pouch-associated hospitalization (hazard ratio=2.39; 95% CI: 1.59, 3.58; P<0.001). The presence of AD was not associated with increased risk for irritable pouch syndrome, active pouchitis, Crohn's disease, cuffitis, surgical complications, or pouch failure. Patients with Crohn's disease of the pouch had a 2.42 times higher risk for pouch failure (P=0.042) than these without. Active smoking or a history of smoking was shown to be associated with an increased risk for pouch-associated hospitalization and pouch failure.

CONCLUSIONS

AD appears to be associated with an increased risk for CARP, and the presence of the association between these AD and pouch disorders may stimulate further research on the link of these organ systems on an immunological basis.

Predictors for acute and chronic pouchitis following restorative proctocolectomy for ulcerative colitis

OBJECTIVE

This study was undertaken to evaluate the cumulative incidence, onset and risk predicting factors for acute and chronic pouchitis.

METHOD

A consecutive series of patients (n = 210), who underwent restorative proctocolectomy (RPC) and had a minimum follow-up of 12 months was reviewed. The cumulative incidence and onset of pouchitis was determined. Univariate analysis, followed by logistic regression analysis was used to evaluate the association of various demographic, clinical and histopathologic variables with the subsequent development of acute and chronic pouchitis.

RESULTS

A total of 198 patients were included. The mean follow-up was 64 months (range, 12-180). Sixty-four patients (32%) developed pouchitis, 35 acute and 29 chronic. The first episode of pouchitis occurred within the first year in 70% of cases. The presence of backwash ileitis (OR, 2.6; P = 0.015), primary sclerosing cholangitis (PSC; OR, 2; P = 0.018) and the duration of follow-up (OR, 1.1; P = 0.043) were associated with a higher incidence of pouchitis. The duration of follow-up was the only variable associated with acute pouchitis (P = 0.007). The presence of backwash ileitis and PSC were independent risk factors for chronic pouchitis (OR, 5.9; P < 0.001; OR, 2.8; P = 0.001 respectively).

CONCLUSION

Pouchitis is a heterogeneous disease which tends to occur early after restoration of gastrointestinal continuity. Patients with backwash ileitis and/or PSC are at considerable risk of developing chronic pouchitis. The strong association between backwash ileitis, PSC and chronic pouchitis suggests a common link in their pathogenesis.

Permanently increased mucosal permeability in patients with backwash ileitis after ileoanal pouch for ulcerative colitis

OBJECTIVE

Backwash ileitis (BI) has not been identified as a risk factor for pouchitis. The aim of this study was to investigate the barrier function of the ileoanal pouch depending on the presence of BI. The incidence of pouchitis in a population of ulcerative colitis patients with BI is also reported.

MATERIAL AND METHODS

Biopsies were taken from 80 patients with ulcerative colitis: a) terminal ileum prior to pouch creation (pre-IAP); b) 16 months after ileostomy closure (intact pouch); and c) during pouchitis. Patients were stratified into the BI group and the non-BI (ØBI) group. Barrier function was determined in Ussing-chambers as epithelial resistance by impedance analysis and as mannitol permeability from (3)H-mannitol fluxes. Na(+)-glucose co-transport was measured as a change in short-circuit current (I(SC)) after addition of glucose. Relative risk of developing pouchitis was calculated by corrected chi(2) test.

RESULTS

In 13/21 (BI/ØBI) pre-IAP patients, 23/37 (BI/ØBI) with an intact pouch, and 35/7 (BI/ØBI) with pouchitis, epithelial resistance in BI/ØBI was 13.5+/-1.6/14.3+/-0.9 Omega.cm(2) for pre-IAP, 12.7+/-1.3/16.8+/-1.2 Omega x cm(2) (p<0.05 BI versus ØBI) for the intact pouch, and 10.1+/-1.1/9.9+/-1.8 Omega x cm(2) for pouchitis (p<0.05 BI versus ØBI with an intact pouch). No differences were found for electrogenic chloride secretion and active Na(+)-glucose co-transport between BI/ØBI in the three groups. In patients with BI, pouchitis was more common (35 versus 7 patients, odds ratio 33.0 (95% CI 8.3-143.9; p<0.0001)).

CONCLUSIONS

Ulcerative colitis patients with BI show impaired barrier function in the further course of the ileoanal pouch. Thus, BI has a long-term impact on epithelial barrier function.

Impact of orthotopic liver transplant for primary sclerosing cholangitis on chronic antibiotic refractory pouchitis

BACKGROUND & AIMS

The effect of orthotopic liver transplantation (OLT) for primary sclerosing cholangitis (PSC) and post-OLT immunosuppression on the disease course of pouchitis is not clear. The aims of this study were to compare the frequency of chronic antibiotic-refractory pouchitis (CARP) in PSC patients with or without OLT and to assess potential risk factors for CARP in these patients.

METHODS

Ulcerative colitis patients with PSC and ileal pouch-anal anastomosis (IPAA) with or without OLT identified from our prospectively maintained pouch database were analyzed. CARP was diagnosed based on persistent symptomatic pouchitis after a 4-week single- or dual-antibiotic therapy.

RESULTS

A total of 63 PSC/IPAA patients were studied, including 19 patients with OLT and 44 patients without OLT. Fifty patients (79.4%) had CARP. In both univariable and multivariable analyses (adjusting for OLT status), none of the variables studied was associated significantly with CARP (P > .20). All 7 patients (100%) with IPAA-then-OLT were diagnosed as having CARP, of whom 4 developed CARP before OLT, which persisted after OLT, and 3 had CARP after OLT. Of 12 patients with OLT-then-IPAA, 7 (58.3%) developed CARP. The frequency of CARP in OLT-then-IPAA was statistically significantly lower than that in IPAA-then-OLT (58.3% vs 100%; P = .047).

CONCLUSIONS

CARP is common in patients with ulcerative colitis and PSC. OLT in these patients may not affect the frequency of CARP in general and appears not to alter the disease course of pre-existing CARP. However, in a subset of patients, OLT might reduce the risk for the development of de novo CARP.

Pouchitis

While restorative proctocolectomy with ileal pouch-anal anastomosis has significantly improved the quality of life in patients with underlying ulcerative colitis who require surgery, complications can occur. Pouchitis as the most common long-term complication represents a spectrum of disease processes ranging from acute, antibiotic-responsive type to chronic antibiotic-refractory entity. Accurate diagnosis using a combined assessment of symptoms, endoscopy and histology and the stratification of clinical phenotypes is important for treatment and prognosis the disease. The majority of patients respond favorably to antibiotic therapy. However, management of chronic antibiotic-refractory pouchitis remains a challenge.

A prospective multivariate analysis of clinical factors associated with pouchitis after ileal pouch-anal anastomosis

BACKGROUND & AIMS

Although acute pouchitis (AP) after ileal pouch-anal anastomosis (IPAA) for UC is common and easily treated, chronic pouchitis (CP) remains a difficult management issue. The aim of this study was to identify important clinical risk factors associated with AP or CP.

METHODS

AP and CP were prospectively assessed, and demographic, disease, and treatment characteristics were tabulated. Univariate and multivariate analyses were performed to evaluate associations between AP or CP and potential risk factors.

RESULTS

Two hundred IPAA patients were followed for a median of 24 months (range, 3-117 months). Thirty-six patients (18%) developed AP, and 23 patients (12%) developed CP. On univariate analysis, the use of steroids before colectomy and smoking were associated with the development of AP. CP was associated with male gender, smoking, length of follow-up, extraintestinal manifestations, backwash ileitis, and elevated (450x10(9)/L) platelet count. On multivariate analysis, the following risk factors were found to be independently associated with AP: use of steroids before colectomy (odds ratio [OR], 3.7; 95% confidence interval [CI], 1.5-8.9; P = .004) and smoking (OR, 2.3; 95% CI, 1.1-5.3; P = .04). CP was directly associated with extraintestinal manifestations (OR, 3.5; 95% CI, 1.1-11.1; P = .03), elevated platelet count (OR, 3.1; 95% CI, 1.1-8.9; P = .03), and increased length of follow-up (OR, 1.3; 95% CI, 1.1-1.6; P = .002). Smoking reduced the incidence of CP (OR, 0.2; 95% CI, 0.05-0.74; P = .04).

CONCLUSIONS

Clinical factors associated with AP included use of steroids before colectomy and smoking. Factors directly related to CP were extraintestinal manifestations, elevated platelet count, and length of follow-up after IPAA. Smoking appears to protect against the development of CP.

Vascular endothelial growth factor and cyclooxygenase-2 are overexpressed in ileal pouch-anal anastomosis

PURPOSE

Pathophysiology of pouchitis after ileal pouch-anal anastomosis is controversial because of the potential for development of carcinoma. Cyclooxygenase-2-derived prostaglandins may be involved in the inflammatory process and play a role in the pathogenesis of colon cancer. Vascular endothelial growth factor plays a major role in neoangiogenesis and is overexpressed in a number of gastrointestinal malignancies. The goal of this study was to evaluate the expression of cyclooxygenase-2 and vascular endothelial growth factor and to assess neoangiogenesis and epithelial cell proliferation in patients with ileal pouch-anal anastomosis.

METHODS

Endoscopic biopsies were obtained from 15 patients with ileal pouch-anal anastomosis without pouchitis (10 biopsies from the ileal pouch and 10 from ileal nonpouch mucosa) and from 15 subjects with irritable bowel syndrome (10 biopsies from normal-appearing ileum and rectum). Cyclooxygenase-1, cyclooxygenase-2, and vascular endothelial growth factor messenger ribonucleic acid expression was determined by reverse transcriptase polymerase chain reaction. Cyclooxygenase-2 and vascular endothelial growth factor protein expression was evaluated by Western blot. Cyclooxygenase-2, vascular endothelial growth factor, CD34 (neoangiogenesis marker), and Ki67 (proliferation marker) mucosal localizations were evaluated by immunohistochemistry.

RESULTS

Expression of cyclooxygenase-2 and vascular endothelial growth factor was increased in ileal pouch mucosa compared with ileal nonpouch mucosa, normal ileum, and rectum. Cyclooxygenase-2 and vascular endothelial growth factor immunostaining in ileal pouch mucosa was more intense in the crypt area than in the surface epithelium compared with ileal nonpouch mucosa. CD34 (neoangiogenesis marker) and Ki67 (proliferation marker) expression was increased in ileal pouch mucosa.

CONCLUSIONS

Cyclooxygenase-2 and vascular endothelial growth factor are overexpressed in the ileal pouch mucosa. This is associated with increased proliferative activity and neoangiogenesis. Cyclooxygenase-2 and vascular endothelial growth factor overexpression might play a role in the pathogenesis of pouchitis.

Serum biochemical evaluation of patients with functional pouches ten to 20 years after restorative proctocolectomy

BACKGROUND

Restorative proctocolectomy with an ileal pouch-anal anastomosis is a surgical treatment of choice for ulcerative colitis and familial adenomatous polyposis (FAP). Pouchitis is a significant enigmatic morbidity. In the long-term, these patients, we anticipated, would experience biochemical profiling alterations after years of retaining functionally acceptable pouches. This pilot study was aimed at assessing results of essential biochemical variables more than 10 years after surgery.

METHODS

The investigation was carried out in 91 patients; 39 were women. Eight-eight had ulcerative colitis, while three had FAPs. The hand-sewn ileal reservoirs after mucoso-proctocolectomy were 66 S and 25 J. The analyses were compared short-term vs long-term. Patients were investigated and were their own control.

RESULTS

Long-term, incidence of acute and chronic pouchitis was 2 and 13%. Eleven and 4% of patients had hypomagnesaemia and hypocalcaemia. Mean levels were significantly enhanced (p<0.01 and p<0.0002). Hypomagnesaemia corresponded to episodes of pouchitis and was corrected with oral magnesium and antibiotics. Hypoferric anaemia was diagnosed in 7% and treated with oral iron tablets. Chronic pouchitis and recurrent pouch mucosa bleeding were the cause. Hypohemoglobinemia and hypocyanocobalaminemia were noted in 5% and 5%, respectively. Erythrocyte sedimentation rate and white blood cells were supra-normal in 13 and 10%, which corresponded with pouchitis. A significant (p<0.03) steady rise of mean serum immunoglobulin G without correlation to pouchitis was noted.

CONCLUSION

Long-term functional results did not deteriorate. Pouchitis was a significant enigmatic morbidity. Severe or chronic pouchitis complicated hypoferric and vitamin B(12) anemia and hypomagnesaemia.

Ileitis in ulcerative colitis: is it a backwash?

PURPOSE

This study aims to determine the incidence, demography, pathologic nature, and clinical significance of ileitis in ulcerative colitis patients who underwent restorative proctocolectomy.

METHODS

A prospectively collected pouch database and the case notes of 100 consecutive patients who underwent restorative proctocolectomy for ulcerative colitis, under the care of a single surgeon, between 1988 and 2003 were reviewed. The original proctocolectomy specimens and pouch biopsies were reexamined and regraded blind, using the current diagnostic criteria. Patients were divided into two groups, those who had ileitis and those who had not. The demographic, clinical, and pathologic characteristics and the incidence of pouchitis of both groups were compared.

RESULTS

Twenty-two patients had ileitis (22 percent). Compared with those with noninflamed ileum, patients with ileitis had a significantly shorter disease duration (P < 0.005), many of them presented or progressed to a fulminant state requiring acute surgical intervention (P < 0.01), had strong association with pancolitis and primary sclerosing cholangitis (P < 0.001), and had a higher incidence of subsequent development of pouchitis (P < 0.001). There was no correlation between the presence of ileitis and colitis severity.

CONCLUSIONS

Ileitis in ulcerative colitis is not rare and does influence the prognosis, and the term "backw ash" is a misnomer. Ulcerative colitis with ileitis represents a distinct disease-specific subset of patients. Its true incidence and clinical significance can be determined only if detailed microscopic characterization of the terminal ileum is performed routinely in every patient with ulcerative colitis and the clinical outcome of these patients is audited prospectively.

Pouchitis: a spectrum of diseases

Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgical treatment of choice for ulcerative colitis and familial adenomatous polyposis patients who require surgery. Pouchitis is the most common long-term complication after IPAA. Patients with pouchitis represent a heterogeneous group in terms of pathogenesis, clinical presentation, disease course, and prognosis, suggesting a wide range of disease mechanisms. Before the diagnosis of pouchitis is made, other inflammatory and non-inflammatory disease conditions, such as Crohn's disease, cuffitis, and irritable pouch syndrome, should be ruled out. Pouch endoscopy is the most important tool for diagnosis and differential diagnosis. Accurate diagnosis and classification are essential for appropriate management. Although the majority of patients with pouchitis respond to antibiotic therapy, a subset of these patients cannot achieve remission by means of antibiotics and thus require anti-inflammatory or immunosuppressive treatment.

Implications of pouchitis on the functional results following stapled restorative proctocolectomy

PURPOSE

Pouchitis is the most frequent long-term complication of restorative proctocolectomy; its long-term consequences are inadequately described. This prospective study evaluates the effect of pouchitis on the functional results, general health perception, and patient satisfaction.

METHODS

A total of 100 consecutive patients who underwent stapled restorative proctocolectomy for ulcerative colitis were divided into three groups: no pouchitis, acute pouch-itis and chronic pouchitis. Functional results, general health perception, and satisfaction of each group at the latest review were compared only when patients were not symptomatic of active pouchitis.

RESULTS

Pouchitis occurred in 33 patients (17 acute and 16 chronic). There were no significant differences in the long-term functional results between the no pouchitis and acute pouchitis groups. Patients who experienced chronic pouchitis had a significant increase in bowel movements, looseness of stools, urgency, nocturnal seepage, perianal excoriation, and dietary restrictions (P < 0.05). They also had a worse perception of their general health (P < 0.05). Previous chronic pouchitis had no effect on continence, daytime soilage, or gas-feces discrimination. Most patients were satisfied, despite pouchitis, and would recommend the operation to someone else with ulcerative colitis.

CONCLUSIONS

Acute pouchitis is easily treated and results in minimal functional consequences. Even in the absence of clinically active pouchitis, patients who had suffered from chronic pouchitis had poorer functional results and general health perception. This may overshadow the benefits of restorative proctocolectomy. This finding suggests that acute and chronic pouchitis are distinct disease entities and chronic pouchitis may represent a persistent condition that displays episodic symptomatic exacerbation.

Mucin gene expression in the ileoanal reservoir is altered and may be relevant to the risk of inflammation and dysplasia

BACKGROUND

Adaptive colonic phenotypic change of the ileal mucosa is a feature of the ileoanal reservoir (IAR) with time, as described by mucin glycoprotein and histological analysis. Mucin gene expression is altered in colorectal neoplasia and inflammatory bowel disease but little is known of its expression in the IAR.

AIMS

To examine the changes in mucin gene expression contributing to mucosal protection of the IAR against a background of known changes occurring in inflammatory disease and colorectal neoplasia.

PATIENTS

Paraffin embedded specimens from 29 "W" and 11 "J" ileoanal reservoirs were studied. Colonic and ileal control tissue was obtained from normal resection margins.

METHODS

Mucin mRNA was detected by in situ hybridisation using [(35)S]dATP labelled oligonucleotide probes. Mucin core protein was detected by immunohistochemistry.

RESULTS

There was no change in mRNA expression of MUC1-4 in the IAR compared with ileal controls but there was a decrease in the protein product of MUC1 and MUC3. No mRNA transcripts of MUC5AC, 5B, or 6 were detected but protein product of MUC5AC and MUC6 was detected. Both cases of MUC6 positivity and 1/5 cases of MUC5AC positivity were confined to the ulcer associated cell lineage. No dysplasia was detected.

CONCLUSIONS

There is a change in the pattern of the membrane associated mucins MUC1 and MUC3, part of which is in keeping with changes described in colorectal neoplasia. A small number of cases demonstrated mucin gene changes (MUC5AC) which are seen in early neoplasia and this may provide a valuable monitor for such changes in IAR surveillance.

Impairment of epithelial transport but not of barrier function in idiopathic pouchitis after ulcerative colitis

BACKGROUND AND AIMS

Little is known of the permeability of ileoanal pouches. Hence the aim of the present study was to determine changes in permeability and mucosal function after ileo-pouchanal anastomosis (IPAA) in patients with ulcerative colitis.

MATERIALS AND METHODS

Biopsies were taken from 43 patients (male:female ratio 28:15; mean age 35.2 (12.5) years) prior to colectomy (ileum prior to pouch), prior to closure of ileostomy (deviation), and after closure of ileostomy (intact pouch) in the case of pouchitis, and from 14 healthy controls. Tissues were mounted in a miniaturised Ussing chamber. Epithelial and subepithelial resistance was determined by transmural impedance analysis. Active Na(+)-glucose cotransport was measured as change in short circuit current after stepwise addition of glucose, and active Cl(-) secretion was measured after stimulation with theophylline and prostaglandin E(2).

RESULTS

Neither epithelial resistance nor mannitol fluxes were significantly altered compared with intact controls, indicating no barrier defect in pouchitis. Subepithelial resistances of intact pouches and pouchitis were increased compared with deviation (18.2 (1.6) and 24.3 (1.5) v. 13.6 (1.0) Omegaxcm(2)) consistent with an adaptive thickening of the subepithelial layer. In contrast, active Cl(-) secretion of pouchitis tissues was reduced versus intact pouch and controls (1.4 (0.3) v. 4.3 (0.7) and 4.6 (0.7) micromol/h/cm(2)), and Na(+)-glucose cotransport of pouchitis was reduced compared with intact pouch and controls (1.8 (0.5) v. 4.2 (0.8) and 8.8 (1.3) micromol/h/cm(2)).

CONCLUSIONS

Ileal mucosa in pouchitis and terminal ileum prior to IPAA exhibit impaired secretory and absorptive transport functions whereas the epithelial barrier function remains unchanged. This differs from findings in ulcerative colitis. Thus the hypothesis that pouchitis represents a remanifestation of ulcerative colitis has to be questioned.

Mucin expression in the ileoanal reservoir reflects incomplete mucosal adaptation

Restorative proctocolectomy is regarded as a standard surgical procedure for patients who require a proctocolectomy for ulcerative colitis and familial adenomatous polyposis. The ileal mucosa undergoes colonic phenotypic change with time, but the extent and relevance of these changes to the long-term safety of the ileoanal pouch are unclear. The aim of this study was to study the mucin biology of this adaptive process in order to assess its extent and possible impact on pouch safety. Ileoanal pouch biopsies from a cohort of patients and normal ileal and colonic controls were subjected to histological, biochemical, histochemical, and immunohistochemical mucin analysis. Mucin sulphation and sialic acid O-acetylation were studied as parameters of colonic phenotypic change. Fifty-one patients, 16 ileal, and 22 colonic controls were studied. Seventy per cent of biopsies retained villous mucosal architecture, with no cases of dysplasia detected. Ileoanal pouch mucosal sulphation and sialic acid O-acetylation did not reach colonic levels, thus indicating limited evidence for a more colonic phenotype. The data from this study suggest that colonic phenotypic change within the ileoanal reservoir is incomplete, with no cases of dysplasia detected. The degree of phenotypic change is less than in previous studies, which may support, but not prove, our hypothesis that there may be a process of reversion to an ileal type mucosa in the ileoanal reservoir with time.

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.

Long term metabolic consequences of ileal pouch-anal anastomosis for ulcerative colitis

OBJECTIVES

Chronic inflammation in the ileal pouch is the most significant late complication after ileal pouch-anal anastomosis (IPAA). It leads to changes in mucosal morphology, with consequent decreased vitamin B12, bile acid and cholesterol absorption documented. The aims of this study were to evaluate long term metabolic consequences at least 5 yr after IPAA and the influence of pouchitis on pouch histology and on bile acid, lipid, and vitamin B12, A, E, and D metabolism.

METHODS

A total of 104 patients with a J-pouch who were operated on between 1985 and 1994, as well as 21 ulcerative colitis patients with a conventional ileostomy were enrolled for the study. Routine blood tests, vitamin status, vitamin B12 levels, and bile acid absorption were determined, as well as endoscopy with biopsies. The pouchitis disease activity index (PDAI) was calculated. On the basis of histology, IPAA patients were divided into three subgroups: 1) those with no villous atrophy, 2) those with partial villous atrophy, and 3) those with subtotal or total villous atrophy.

RESULTS

Incidence of pouchitis was 42.3%, and was strongly associated with villous atrophy. In IPAA patients with subtotal or total villous atrophy (32.7%), serum levels of albumin, calcium, total cholesterol, triglycerides, and vitamin E were significantly reduced (p < 0.05). The lowest bile acid and vitamin B12 absorption rates were seen in patients with inflammation in the proximal limb. Vitamin D deficiency was seen in 10.6%, and vitamin A and B12 deficiency in approximately 5% of IPAA patients.

CONCLUSIONS

Metabolic consequences after IPAA are associated with pouchitis, grade of villous atrophy, and extent of inflammation in the remaining ileum. Patients with active chronic inflammation need long term follow-up.

Intestinal permeability in Crohn's disease patients and their first degree relatives

BACKGROUND

Family studies suggested that an altered intestinal permeability plays a role in the genesis of Crohn's disease.

AIM

Aim of the present study was to investigate a possible genetic alteration of the mucosal barrier in Crohn's disease.

SUBJECTS

16 Crohn's disease patients and 26 of their cohabiting first degree relatives were studied.

METHODS

To investigate intestinal permeability, Cellobiose/Mannitol test was administered to both groups.

RESULTS

In the two groups, we found that the median intestinal permeability values were higher and statistically different from those obtained in 32 healthy control subjects as well as in five healthy control families. Six (37.5%) Crohn's disease patients and three (11.5%) of their first degree relatives showed increased individual intestinal permeability values. Intestinal permeability alteration in Crohn's disease patients was unrelated to sex, age, disease activity, localisation, duration, treatment schedule, as well as to serum anti-Saccharomyces cervisiae antibody positivity in a pilot study conducted in 7 Crohn's disease patients; anti-Saccharomyces cervisiae antibody values were negative in all 10 first degree relatives investigated.

CONCLUSIONS

These findings demonstrate the increase in IP in 37% of the patients and in 11% of their relatives. More extensive investigation of the correlation between ASCA alterations and IP will be needed in both patients with Crohn's disease and their relatives.

Expression of inducible and endothelial nitric oxide synthases in pouchitis

To study the induction of nitric oxide synthase (NOS) in different forms of pouchitis, we divided patients in five groups: 1) ulcerative colitis, no pouch; 2) no-pouchitis; 3) chronic asymptomatic pouchitis; 4) chronic active pouchitis; and 5) acute pouchitis. Ileal biopsies were scored for NOS-2 (inducible) and NOS-3 (endothelial) immunoreactivity and acute inflammation. In group 1, most specimens lacked NOS-2 immunoreactivity. In group 2, some specimens showed NOS-2 immunoreactive epithelium. In group 3, areas of NOS-2-immunoreactive epithelium were consistently observed in most specimens. In groups 4 and 5, most specimens showed moderate-to-extensive epithelial NOS-2 staining. NOS-2 immunoreactivity scores of groups 1-5 were 0.25 +/- 0.16, 0.67 +/- 0.19, 1.19 +/- 0.40, 2.0 +/- 0.23, and 2.18 +/- 0.12, respectively. Corresponding acute inflammation scores were 0, 0.53 + 0.17, 1.00 +/- 0.33, 1.80 +/- 0.20, and 1.64 +/- 0.15. NOS-2 score correlated with acute inflammation score (p < 0.0001), indicating that NOS-2 induction correlates with both the clinical degree of pouchitis and the severity of acute inflammation. NOS-3 immunoreactivity increased in all pouchitis groups.

The jejunal pouch as a rectal substitute after proctocolectomy

Our hypothesis was that a jejunal pouch used as a rectal substitute after proctocolectomy would slow enteric transit, delay defecation, and decrease stool frequency compared to an ileal pouch so used. Twelve dogs underwent proctocolectomy; six had a jejunal pouch-distal rectal anastomosis and six had an ileal pouch-distal rectal anastomosis. After recovery, postprandial mouth-to-anus transit was slower in jejunal pouch dogs (253 +/- 18 minutes [mean +/- SEM]) than in ileal pouch dogs (112 +/- 7.9 minutes; P <0.05). Moreover, jejunal pouch dogs passed only 4.1 +/- 0.3 stools during the 12 hours after eating, whereas ileal pouch dogs passed 6.3 +/- 0. 9 stools (P <0.05). The mean frequency of proximal ileal pacesetter potentials after feeding was less in jejunal pouch dogs (12 +/- 0.4 cycles/min) than in ileal pouch dogs (16 +/- 0.3 counts/min; P = 0. 01), and jejunal pouches had more action potentials (jejunal = 82% +/- 4.3% of pacesetter potentials had action potentials, ileal = 61% +/- 3.0%; P <0.05). In contrast, gastric emptying and pouch motility, emptying, mucosal integrity, and bacteriologic and histologic properties were similar in the two groups of dogs. We concluded that the jejunal pouch operation slowed enteric transit, delayed defecation, and decreased postprandial stooling compared to the ileal pouch operation.

Ileal pouches: adaptation and inflammation

Ileal pouch-anal anastomosis (IPAA) has become the operation of choice following proctocolectomy for ulcerative colitis (UC) and familial adenomatous polyposis. Functioning ileal pouch mucosa undergoes histological changes resembling the colon (colonic metaplasia). The possible role of stasis and luminal factors--bile acids, short-chain fatty acids and bacteria--are discussed. It seems likely that colonic metaplasia is an adaptive response to the new luminal environment in IPAA. Inflammation in the ileal reservoir ('pouchitis') is the most significant late complication in IPAA. It occurs in 20-30% of patients and is virtually confined to those with prior UC. The clinical picture in pouchitis is highly variable; however, it can be easily categorized into three groups. Nevertheless, in most cases it is likely to represent recurrent UC in the ileal pouch. Current treatments and possible preventative strategies for pouchitis have been outlined.