Extensive pathological changes of the colon in cystic fibrosis and high-strength pancreatic enzymes

Pathogenesis of fibrosing colonopathy: the role of methacrylic acid copolymer

Fibrosing colonopathy is a serious bowel disorder which was first seen in 1991 in patients with cystic fibrosis treated with high doses of pancreatic enzyme supplements. Epidemiological evidence from two case-control studies, temporal data and direct experimental evidence support the conclusion that there is a causal relationship between the disease and intake of high doses of the excipient, methacrylic acid copolymer, which is used to coat certain brands of pancreatic enzyme. A high intake of lipase, the active ingredient in pancreatic enzymes, is not a risk factor for fibrosing colonopathy in the absence of methacrylic acid copolymer. Excipients may be toxic if used in new patient populations such as children and in doses exceeding the safe levels predicted by animal toxicology.

The role of MRI in the intestinal complications in cystic fibrosis

Fibrosing colonopathy is a complication recently detected in children with cystic fibrosis (CF), and is thought to be associated with the use of high-strength pancreatic enzymes. The goal of this study was to evaluate the effectiveness of magnetic resonance (MR) in detecting possible pathologic gut findings in patients with CF under pancreatic enzyme treatment. Twenty-five patients with CF and pancreatic insufficiency, all under treatment with high-dose pancreatic enzymes, were studied by MR. MR was performed on a 1.5-T magnet by T1-weighted, 2D-FLASH fat-suppression, breath-hold sequences before and after intravenous administration of gadolinium, and by T2-weighted Turbo Spin-Echo (TSE) and Half-Fourier Acquisition Single-Shot Turbo Spin Echo (HASTE) fat-suppression, breath-hold sequences. A superparamagnetic negative oral contrast agent was given 1.5 h before the examination. MR showed a wall thickening of the terminal ileum and the ascending colon (>4-12 mm) in 22 patients; nine of them (wall thickness >4-6 mm) showed both a moderate hyperintensity of the bowel wall on T2-weighted sequences and an enhancement after intravenous gadolinium on T1-weighted sequences; 13 patients (wall thickness >6-12 mm) showed both a great wall enhancement after intravenous gadolinium and an increased signal intensity of the bowel wall on T2-weighted sequences. Fecal impaction without bowel wall involvement was detected in three patients. MR proved to be a useful, noninvasive, diagnostic tool for the evaluation of patients with CF and fibrosing colonopathy. The signal hyperintensity on T2-weighted sequences and the great wall enhancement after intravenous gadolinium administration indicating an acute edematous condition, provide the clinicians useful information for the therapeutic adjustment.

Cystic fibrosis colonopathy

An epidemic of fibrosing colonopathy, a new disease caused by the prolonged administration of excessive doses of pancreatic enzymes, was first reported in 1994. More than 60 cases were known to occur worldwide before dosage guidelines were enforced. Predisposing factors were young age, previous intestinal surgery, meconium ileus equivalent, and use of H2 blockers, corticosteroids, and DNase. Abnormal features included foreshortened colon, strictures, marked submucosal fibrosis, ascites, and nodular hyperplasia of the liver. Histologic examination showed eosinophilia, mild cryptitis, epithelial regeneration, and widespread interruption of the muscularis mucosa. These findings are distinct from, but share many of the features of, those of Crohn's's disease and ischemic bowel disease. The pathogenic mechanisms remain unknown.

Cystic fibrosis with fibrosing colonopathy in the absence of pancreatic enzymes

Fibrosing colonopathy, characterized by dense submucosal fibrosis in the large bowel, is a disorder associated with bowel dysfunction in patients with cystic fibrosis who receive pancreatic enzyme supplementation. Most commonly, patients present with a distended abdomen and abdominal pain. Radiographs frequently demonstrate colonic wall thickening and luminal narrowing. Here I describe a neonate with cystic fibrosis who presented with both clinical and histological features of fibrosing colonopathy who had not received pancreatic enzymes. This report expands our understanding of the pathogenesis of fibrosing colonopathy.

High-dose pancreatic-enzyme supplements and fibrosing colonopathy in children with cystic fibrosis

BACKGROUND

Fibrosing colonopathy has been reported in young children with cystic fibrosis, the majority of whom take high-strength pancreatic-enzyme supplements to control intestinal malabsorption. We conducted a case-control study in the United States to investigate the relation between dose and type of pancreatic-enzyme supplement and fibrosing colonopathy.

METHODS

Children with histopathologically confirmed cases of fibrosing colonopathy who required colectomy for colonic strictures from January 1, 1990, through December 31, 1994, were identified. Each of these patients was matched according to age at the time of surgery and medical center with up to four controls with cystic fibrosis who did not have fibrosing colonopathy.

RESULTS

We studied 29 patients (mean age, 5.0 years) with fibrosing colonopathy (case patients) and 105 controls (mean age, 5.2 years). The mean dose of pancreatic-enzyme supplement was 50,046 units of lipase per kilogram of body weight per day for the case patients and 18,985 units per kilogram per day for the controls. A history of gastrointestinal complications attributed to cystic fibrosis and the use of histamine H2-receptor blockers, corticosteroids, or recombinant human DNase (dornase alfa) were associated with a higher incidence of fibrosing colonopathy. After adjustment for a history of such complications and the use of these medicines, the relative risk of fibrosing colonopathy that was associated with a dose of 24,001 to 50,000 units of lipase per kilogram per day, as compared with a dose of 0 to 24,000 units per kilogram per day, was 10.9 (95 percent confidence interval, 1.6 to 71.8), and that associated with a dose of more than 50,000 units per kilogram per day was 199.5 (95 percent confidence interval, 9.9 to 4026.0). The strength, coating, and manufacturer of the products used were not associated with the risk of fibrosing colonopathy.

CONCLUSIONS

In young children with cystic fibrosis, we found a strong relation between high daily doses of pancreatic-enzyme supplements and the development of fibrosing colonopathy. Our findings support recommendations that the daily dose of pancreatic enzymes for most patients should remain below 10,000 units of lipase per kilogram.

The pathology of fibrosing colonopathy of cystic fibrosis: a study of 12 cases and review of the literature

The authors studied eight colectomy and eight biopsy specimens from 12 patients with cystic fibrosis who had developed fibrosing colonopathy, a complication observed in patients receiving high-strength enzyme replacement. The colectomies originated from five male and three female patients ranging in age from 18 months to 6 years. Five individuals had localized strictures of the right colon and three had stenosing fibrosis of the entire colon. The affected colon had a cobblestone appearance, submucosal fibrosis, thickening of the muscularis propria and chronic mucosal inflammation in all patients, with active cryptitis in four. Moderate to severe infiltration by eosinophils, with increase in the number of mast cells, and widespread interruption of the muscularis mucosa were present in every case. Four colectomies were preceded by endoscopic biopsies; four patients who have not undergone surgery also underwent biopsy. All the biopsies showed evidence of active or chronic inflammation, and all had increased mucosal eosinophils. Prolonged colonic mucosal contact with either the enzymes and/or the enteric coating itself may lead to mucosal colonic ulceration and inflammation. Topical allergy may then promote the stenosing fibroplasia.

Colonic stricture in cystic fibrosis unmasked by successful transjugular intrahepatic portosystemic stent shunt (TIPSS)

TIPSS was successfully performed in a 10-year-old female cystic fibrosis (CF) patient with bleeding gastric varices due to portal hypertension; precipitation of portosystemic encephalopathy later unveiled the presence of a latent colonic stricture associated with high potency pancreatic enzymes. The unusual sequence of events resulting from the co-existence of two CF pathologies are described, and the implications of treatment discussed.

Neuropathy and vasculopathy in colonic strictures from children with cystic fibrosis

Colonic strictures are rare in patients who have cystic fibrosis, but recently have developed in those who have been treated with delayed-release high-dose pancreatic enzyme supplements. Colonic strictures from eight such pediatric patients showed neural abnormalities consisting of ganglion cell hyperplasia and ectopia, and intermyenteric plexus hyperplasia. Cholinergic and adrenergic stains of mucosal nerve fibers were more prominent in histological sections of the cystic fibrosis strictures than in sections from colons of children without cystic fibrosis. The mean grade of staining with acetylcholinesterase in the lamina propria of the strictured cystic fibrosis colons was 2.38 +/- 1.25, compared with .93 +/- .93 (P < .055) in bowels from children without cystic fibrosis. The mean grade for tyrosine hydroxylase staining in the lamina propria was 2 +/- .97 in the strictures and was .79 +/- .81 (P < .05) in the bowels of children who did not have cystic fibrosis. Vasoactive intestinal peptide staining in bowels from children with cystic fibrosis with and without stricture did not differ significantly from that of children without cystic fibrosis. Vasculopathy consisting of fibrointimal hyperplasia in submucosal veins and mesenteric arteries was found only in colonic strictures owing to cystic fibrosis. Colonic strictures in patients with cystic fibrosis who received high-dose pancreatic enzyme supplements contain ganglion cell abnormalities, and mucosal cholinergic and adrenergic activity may be increased in these strictures. The stricture vasculopathy may be drug-related and/or related to increased catecholamine activity.

Fibrosing colonopathy in cystic fibrosis

The introduction of enteric coated pancreatic enzyme supplements in the early 1980s was undoubtedly one of the major advances in the care of children with cystic fibrosis. Further refinements in the presentation of these preparations inevitably followed, to improve patient acceptability and compliance. The emergence of fibrosing colonopathy took clinicians dealing with cystic fibrosis completely by surprise, and in the last two years there has been a gradual appreciation that as far as pancreatic enzyme products are concerned 'More is not necessarily better'. However, it is encouraging that, in the UK, there have been no histologically confirmed cases in children receiving high strength pancreatic enzyme preparations since July 1994. Hopefully this trend will continue and the causal factors will be defined, ensuring that this serious complication can be effectively prevented in the future.

Colonic strictures in patients with cystic fibrosis: results of a survey of 114 cystic fibrosis care centers in the United States

We describe 15 cases of stricture of the colon requiring surgery in cystic fibrosis patients identified from a survey of 114 cystic fibrosis care centers in the United States. Patient ages ranged from 2 to 8 years, seven of the 15 patients were female. A history of meconium ileus was reported in nine of the 15 cases. Fibrosis of the submucosa was described in 14 surgical pathology reports. Pancreatic enzyme use history was available from 14 reports. All had taken delayed-release products for 6-96 months at average doses ranging from 6,700 to 29,100 units lipase/kg/meal, but only eight of them used products containing >20,000 units lipase per capsule prior to surgery.

Fibrosing colonopathy in cystic fibrosis: results of a case-control study

Fibrosing colonopathy was first described in cystic fibrosis (CF) children in 1994. We have done a nested case-control study to identify possible associations with this condition. A case ascertainment within the UK CF population to identify any cases that occurred between January, 1984, and April, 1994, found 14 cases, all under 14 years and confirmed by independent histopathological review. All had presented since April, 1993; 12 were boys and six had received some or all of their care in Liverpool. Each case was matched, by date of birth, with four controls from the UK CF Registry. Information was obtained about cases and controls from their case records and by a structured interview with the families. In the 12 months before surgery, there was an association between the occurrence of fibrosing colonopathy and use of high-strength pancreatic enzyme preparations. This association was dose related. Odds ratio per extra 1000 high-strength capsules was 1.45 (95% CI 1.14-1.84). For use of protease, the odds ratio per million extra units per kg was 1.55 (1.19-2.03). For usage of individual high-strength products at any time during the 12 months before surgery some differences were observed; for Creon 25000 the odds ratio was 0.38 (0.10-1.42), for Nutrizym 22 43.4 (2.51-751), and for Pancrease HL 8.4 (1.95-36.1). These last two confidence intervals are extremely wide and compatible with these two products having the same odds ratios. Laxative use was independently predictive (odds ratio 2.42 [1.20-4.94]). We conclude that there is a dose-related association between high-strength pancreatic enzyme preparations and fibrosing colonopathy.

Calcium-activated chloride conductance is not increased in pancreatic duct cells of CF mice

Calcium-activated anion secretion is elevated in the pancreatic ductal epithelium of transgenic cf/cf mice which lack the cystic fibrosis transmembrane conductance regulator (CFTR). To elucidate whether this effect is due to increased activity of calcium-activated chloride channels, we have studied the relationship between CFTR and calcium-activated chloride currents in pancreatic duct cells isolated from Cambridge cf/cf mice. CFTR chloride currents activated by cAMP were detected in 59% (29/49) of wild-type cells and in 50% (20/40) of heterozygous cells. However, we could not detect any CFTR currents in the homozygous cf/cf cells (0/25). The maximum CFTR current density measured at a membrane potential of 60 mV was 23.5 +/- 2.8 pA/pF (n = 29) in wild-type cells, and about half that value, i.e. 12.4 +/- 1.6 pA/pF (n = 20) in heterozygotes (P = 0.004). Calcium-activated chloride currents were detected in 73% (24/33) of wild-type, 75% (21/28) of heterozygous and in 58% (7/12) of homozygous cf/cf cells. There was no significant difference between the steady-state calcium-activated current densities in the three genotypic groups; the current measured at 60 mV being 527 +/- 162 pA/pF (n = 24) from wild-type, 316 +/- 35 pA/pF (n = 21) from heterozygote and 419 +/- 83 pA/pF (n = 7) from homozygous cells. Our data suggest that lack of CFTR does not enhance the calcium-activated chloride conductance in murine pancreatic duct cells.

Relation of thickening of colon wall to pancreatic-enzyme treatment in cystic fibrosis

Fibrotic strictures of the colon in association with colon-wall thickening on abdominal ultrasound have been described in children with cystic fibrosis. We determined the prevalence of colon-wall thickening in 99 children with cystic fibrosis (aged 6 months to 17 years, 45 male) and 38 healthy controls (aged 1 month to 39 years, 21 male). In controls, peristalsis was uniformly rapid and maximum wall thickness of the fully relaxed colon was 0.8 mm (median 0.6 mm). 24% of the patients had a colon-wall thickness of 1.5 mm or more (maximum 3.4 mm); 48% of children on high-strength pancreatin receiving more than 265 units/kg per day of protease had thickening of more than 1.5 mm compared with less than 12% of children on any other dose. Children on high-strength pancreatin were 5.2 (95% CI 1.2-21) times more likely to have colon-wall thickness of 1.5 mm or more than children taking less than 265 units/kg per day of protease in a standard-strength preparation. This risk rose to 10 (2.5-39) times more likely if laxatives were taken with a high-strength preparation. Lipase or amylase intake, age, sex, genotype, and other medical or drug history were not significantly associated with colon-wall thickening. 1 child required a hemicolectomy for bowel obstruction and another developed haemorrhagic colitis. In 17 children, 2 months after stopping high-strength, high protease, preparations and efforts to reduce enzyme intake, colon-wall thickness had regressed from a median 2.0 mm (range 1.0-3.4) to 1.8 mm (0.9-2.7) (p = 0.005). The use of high-strength pancreatin preparations in conjunction with a high protease intake probably causes thickening of the wall of the colon.