Bile acid absorption from ileoanal pouches using enema scintigraphy

Increased Risk of Gallstone Disease Following Colectomy for Ulcerative Colitis

OBJECTIVES

Biochemical studies suggest that patients who have had a colectomy or restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) are at an increased risk of developing gallstone disease, but epidemiological studies are lacking. We evaluated the risk of gallstone disease following colectomy and IPAA.

METHODS

Individuals who had a colectomy were identified from a national cohort of patients with ulcerative colitis (UC), and controls without colectomy were sampled from within the same cohort, matching on gender, calendar year, and year of birth. We used Cox regression to examine the effect of colectomy on the hazard rates of gallstone disease and cholecystectomy, adjusting for alcoholism, stroke, chronic obstructive pulmonary disease, cancer, cardiac disease, diabetes mellitus, hypothyroidism, hyperlipidemia, cirrhosis, obesity, renal failure, and transient ischemic attacks. The effect of an IPAA was determined for patients who had colectomy by including the procedure as a time-dependent variable.

RESULTS

We identified 4548 patients and matched these to 44 372 controls without colectomy. During a median follow-up of 11.9 years, 1963 patients were hospitalized for gallstone disease. Patients who had a colectomy were at an increased risk (adjusted hazard ratio (HR)=1.63 (1.39-1.91)), and sensitivity analyses of the risk of undergoing cholecystectomy revealed a similar association (adjusted HR=1.55 (1.22-1.98)). An IPAA did not affect the risk of developing gallstones among patients who had a colectomy (adjusted HR=1.03 (0.77-1.37)).

CONCLUSION

The risk of gallstone disease increases following colectomy for UC.

Systematic review: bile acids and intestinal inflammation-luminal aggressors or regulators of mucosal defence?

BACKGROUND

Inflammatory bowel diseases (IBD), comprising Crohn's disease and ulcerative colitis (UC), are chronic conditions attributed to an aberrant immune response to luminal triggers. Recently, published work suggests a pathogenic role for bile acids in this context.

AIM

To perform a systematic review of studies investigating the role of bile acids in intestinal inflammation and present potentially relevant clinical implications.

METHODS

Pubmed search for English language articles published up to May 2015. Terms used were: 'bile', 'bile acid', 'barrier', 'small bowel injury', 'Crohn's' and 'colitis'.

RESULTS

Experimental studies support a variable role for bile acids in intestinal barrier homoeostasis. This may be attributed to different physicochemical properties, variable effects on epithelia and immune cells via bile acids-specific receptors, or through a cross-talk with the gut microbiome. A reduction in the bile acids pool, with lower concentrations of secondary forms, has been recognised for some time in Crohn's disease and associated to ileal dysfunction and bile acids malabsorption. Recent work suggests that these changes, including an increase in sulphated forms, are related to inflammatory activity in both Crohn's disease and UC. The detrimental effects of 'western diet' elements such as emulsifiers and fat, which have been implicated in the development of the current IBD and obesity epidemics, may also be bile acid-mediated.

CONCLUSIONS

Although there are only a few observational clinical studies to support an interaction, in vivo human and animal studies support an association between bile acids metabolism, the gut microbiome and intestinal inflammation. This may well prove to have significant diagnostic and therapeutic implications.

Pouchitis: prevention and treatment

PURPOSE OF REVIEW

Pouchitis, representing a spectrum of disease phenotypes, is the most common long-term complication in patients who have undergone restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA). Its management and prevention are challenging.

RECENT FINDINGS

Treatment modalities vary according to phenotypes of pouchitis. The medical therapy of pouchitis remains largely empiric and antibiotic-based. However, patients may develop de-novo chronic antibiotic-refractory pouchitis (CARP) or progress from acute antibiotic-responsive phenotype. Patients with CARP often require alternative medical approaches to routine antibiotics, including the use of oral or topical mesalazine, corticosteroids, and sometimes immunomodulators or biological agents against tumour necrosis factor. There are two strategies to prevent pouchitis, the primary (i.e., the prevention of the initial episode) and secondary (i.e., the prevention of recurrent episodes) prophylaxis. There are scant data in the literature on nutritional aspects.

SUMMARY

We evaluated the efficacy of current strategies of prevention and treatments of pouchitis and propose algorithms, including attention to nutrition wherein data exist.

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.

Nutrition considerations surrounding restorative proctocolectomy

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the surgical treatment of choice for patients with ulcerative colitis and familial polyposis coli syndromes. Pouch construction uses the distal 30-40 cm of ileum, and there exists a potential for postoperative nutrition consequences. These include vitamin B(12) deficiency, iron deficiency, bile acid malabsorption, and abnormalities of trace elements, fluids, and electrolytes. Patients who have undergone an ileal pouch-anal anastomosis procedure often describe specific food sensitivities that may require diet alteration, even more so than do patients with permanent ileostomy. There may be roles for postoperative probiotic supplementation in an attempt to decrease the rate of "pouchitis" and appropriate preoperative nutrition support to minimize the risk of perioperative complications.

Ileal pouch dysfunction: diagnosis and management

Restorative proctocol ectomy is the elective surgical procedure of choice for most patients who have ulcerative colitis or familial adenomatous polyposis. This major advance has offered an alternative to permanent ileostomy in these patients.

Review article: restorative proctocolectomy, indications, management of complications and follow-up--a guide for gastroenterologists

BACKGROUND

Restorative proctocolectomy with ileal pouch-anal anastomosis is the procedure of choice for the majority of patients with ulcerative colitis who require surgery. Over 2500 patients in the UK have undergone restorative proctocolectomy. It is now increasingly being performed in district general hospitals as well as in specialist inflammatory bowel disease units. Gastroenterologists are increasingly involved in the management of patients following restorative proctocolectomy.

AIM

To provide gastroenterologists with a clear understanding of the investigation and evidence-based management of complications and the aftercare required in patients who have undergone restorative proctocolectomy.

RESULTS

Following restorative proctocolectomy, most patients have an excellent long-term functional outcome. Pouchitis, pelvic sepsis and poor function are the most common causes of failure. The development of cancer is rare; nevertheless, long-term follow-up is required.

CONCLUSIONS

The investigation and management of patients who develop complications require a multidisciplinary team approach to optimize the outcome. Protocols are suggested for investigation and management of patients with complications and for long-term cancer surveillance.

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.

Bile acid absorption after near-total proctocolectomy in dogs: ileal pouch vs. jejunal pouch-distal rectal anastomosis

Bile acid malabsorption is often present in patients after near-total proctocolectomy and ileal pouch-anal canal anastomosis, suggesting ileal dysfunction. Experiments were performed in dogs to compare bile acid absorption after a modified procedure, in which a jejunal pouch was interposed between the terminal ileum and the distal rectum, with that after a conventional ileal pouch operation. Fecal bile acid output (equivalent to hepatic bile acid biosynthesis) and composition were determined by gas chromatography/mass spectrometry in five jejunal pouch dogs and in five ileal pouch dogs more than 6 months after operation. Fecal bile acid output in the jejunal pouch dogs (mean +/- standard deviation) was 215 +/- 59 mg/day (10.1 +/- 2.7 mg/kg-day), a value similar to that obtained in the ileal pouch dogs (261 +/- 46 mg/day [12.8 +/- 3.1 mg/kg-day]; P >0.05). These values were also similar to those reported by others for healthy unoperated dogs, indicating that increased bile acid biosynthesis occurring in response to bile acid malabsorption was not present. Fecal bile acids in pouch dogs were completely deconjugated and extensively 7-dehydroxylated (jejunal pouch = 90.4% dehydroxylated; ileal pouch = 88.6% +/- 6.6% dehydroxylated) and consisted predominantly of deoxycholic acid derivatives. We conclude that when either a jejunal pouch or an ileal pouch is used as a rectal substitute in dogs, an anaerobic pouch flora develops that efficiently deconjugates and dehydroxylates bile acids, rendering them membrane permeable. The resultant passive absorption of unconjugated bile acids appears to compensate for any loss of active ileal absorption of conjugated bile acids, and bile acid malabsorption does not occur.

Ursodeoxycholic acid has no influence on function after restorative proctocolectomy in ulcerative colitis

BACKGROUND

Poor pouch function is associated with impaired bile acid absorption and increased faecal loss of bile acids. Bile acid replacement therapy might therefore be of clinical benefit, provided that diarrhoea is not aggravated by therapy.

AIM

To investigate the role of exogenous bile acid therapy in patients with poor pouch function after restorative proctocolectomy for ulcerative colitis.

PATIENTS AND METHODS

Twenty ulcerative colitis patients with poor pouch function (score > 4 on a 12-point score) were recruited for inclusion to a prospective, randomized, double-blind crossover, placebo-controlled trial of ursodeoxycholic acid (10 mg/kg per day in two divided doses for 1 month).

RESULTS

A total of 16 patients completed the study. There was no significant difference in the functional score or bowel frequency following treatment irrespective of whether the active treatment was given before or after placebo.

CONCLUSIONS

We conclude that ursodeoxycholic acid given over 4 weeks had no influence on functional score or bowel frequency after restorative proctocolectomy for U.C.

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.