Urokinase and the intestinal mucosa: evidence for a role in epithelial cell turnover

Background—The functions of urokinase inintestinal epithelia are unknown.
Aims—To determine the relation of urokinaseexpressed by intestinal epithelial cells to their position in thecrypt-villus/surface axis and of mucosal urokinase activity toepithelial proliferative kinetics in the distal colon.
Methods—Urokinase expression was examinedimmunohistochemically in human intestinal mucosa. Urokinase activitywas measured colorimetrically in epithelial cells isolated sequentiallyfrom the crypt-villus axis of the rat small intestine. In separate experiments, urokinase activity and epithelial kinetics (measured stathmokinetically) were measured in homogenates of distal colonic mucosa of 14 groups of eight rats fed diets known to alter epithelial turnover.
Results—From the crypt base, an ascendinggradient of expression and activity of urokinase was associated withthe epithelial cells. Median mucosal urokinase activities in each ofthe dietary groups of rats correlated positively with autologous mediannumber of metaphase arrests per crypt (r=0.68; p<0.005)and per 100 crypt cells (r=0.75; p<0.001), but not withcrypt column height.
Conclusions—Localisation of an enzyme capable ofleading to digestion of cell substratum in the region where cells areloosely attached to their basement membrane, and the association of its activity with indexes of cell turnover, suggest a role for urokinase infacilitating epithelial cell loss in the intestine.

Keywords:urokinase; intestinal epithelium; colon; epithelialproliferation

     

Colonic epithelial cell proliferation in hereditary non-polyposis colorectal cancer

Background—Despite the recentdiscovery of four genes responsible for up to 90% of all cases ofhereditary non-polyposis colorectal cancer (HNPCC), there will still befamilies in whom predictive testing is not possible. A phenotypicbiomarker would therefore be useful. An upwards shift of theproliferative compartment in colonic crypts is reported to be one ofthe earliest changes in premalignant mucosa.
Aims—To assess the role of cryptcell proliferation as a phenotypic biomarker in HNPCC.
Patients—Thirty five patients at50% risk of carrying the HNPCC gene (21 of whom subsequently underwentpredictive testing and hence gene carrier status was known) and 18controls.
Methods—Crypt cell proliferationwas measured at five sites in the colon using two different techniques.Labelling index was determined using the monoclonal antibody MIB1 andwhole crypt mitotic index was measured using the microdissection andcrypt squash technique. The distribution of proliferating cells within the crypts was also assessed.
Results—There were no significantdifferences in the total labelling index or mean number of mitoses percrypt, nor in the distribution of proliferating cells within the crypt,between the study and control groups at any site. When the 21 patients in whom gene carrier status was known were analysed separately therewere no significant differences in the measured indices ofproliferation between the HNPCC gene carriers and non-gene carriers.
Conclusion—Crypt cell proliferationis not a discriminative marker of gene carriage in HNPCC.

Keywords:cell proliferation; hereditary non-polyposiscolorectal cancer

     

Severe upper gastrointestinal polyposis associated with sparse colonic polyposis in a familial adenomatous polyposis family with an APC mutation at codon 1520

Background—Familial adenomatouspolyposis usually results in colonic polyposis with hundredsto thousands of polyps, congenital hypertrophy of the retinal pigmentepithelium (CHRPE), and variable extracolonic features. Recent reportsindicate that patients with distal mutations between codons 1445 and1578 do not express CHRPE and have a high incidence of desmoid tumours.
Patients—The family studied has an unusualphenotype of sparse colonic polyposis but profuse uppergastrointestinal polyposis. Affected subjects do not have CHRPE.
Methods—The protein truncation testfollowed by sequencing identified a 2 base pair deletion at codon 1520 in the APC gene. This results in a frameshift creating a stop codon 13 codons downstream.
Results—This family demonstrates that sparsecolonic polyposis but severe upper tract polyposis may be associatedwith mutations between codons 1445 and 1578.
Conclusions—Study of duodenal and colonic polypsin further cases with mutations in this region is warranted. Suchmutations may preferentially cause duodenal adenomas and desmoidtumours as somatic mutations in these tumours also occur in thisregion, unlike colorectal tumours where somatic mutations occur moreproximally. This study emphasises the importance of screening the uppergastrointestinal tract even when the colonic disease is mild.

Keywords:familial adenomatous polyposis; duodenal polyps; APCmutations; colorectal polyps

     

Mucin gene expression in human embryonic and fetal intestine

Background—The intestinal epithelium is coveredby a continuous layer of mucus which is secreted by well differentiatedepithelial cells. Disregulation of the expression of mucins has beenreported to have possible implications in the neoplastic process which affects intestinal mucosae. It is well known that preneoplastic andneoplastic tissues can express fetal phenotypic characteristics.
Aims—To assess whether the expression of mucingenes in the intestinal tract is linked to the stage of cellulardifferentiation and tissue development, by studying the expression ofsix mucin genes in human fetal small intestine and colon, and alsoadult tissues.
Methods—In situ hybridisation was used to studymRNA expression of MUC2, MUC3, MUC4, MUC5B, MUC5AC, and MUC6 in 32 human embryos and fetuses (6.5-27 weeks gestation). Normal adultmucosae were used as controls.
Results—Three mucin genes, MUC2, MUC4, andMUC5AC, were differently expressed in fetal intestine compared withexpression in normal adults.
Conclusion—These differences in mucin geneexpression suggest a possible regulatory role for these products inintestinal epithelial cell differentiation.

Keywords:mucin genes; mucins; intestine; differentiation; human fetus

     

The distal colon provides reserve storage capacity during colonic fluid overload

Background—In addition to its absorptive functionthe capacity of the colon to retain fluid might be relevant incompensating for increased fluid loads and prevention of diarrhoea. Thedistal colon is considered to be mainly a conduit without extensivestorage function.
Aims—To evaluate colonic volume capacity in amodel of pure osmotic diarrhoea.
Methods—A non-absorbable, iso-osmotic solution(OS) containing polyethylene glycol (500 ml) was infused into thecaecum of nine healthy volunteers; the control group (n=5) received anequal amount of an easily absorbable electrolyte solution (ES). Fluids were radiolabelled with technetium-99m and gamma camera images wereobtained for 48 hours. Counts in the proximal and distal colon weremeasured and regional and overall colonic transit and stool output were quantified.
Results—After OS, in contrast to ES, faecal outputwas increased significantly (p<0.05), but colonic transit after OS was not different from transit after ES (p>0.05). This indicates storage of OS in the colon: after OS infusion, counts in the proximal colondecreased linearly while the distal colon stored approximately 30% ofradioactivity for the whole 48 hour study period. After OS, stooloutput correlated with distal (p<0.01), but not with proximal(p>0.05), colonic transit. In constrast, after ES, stool output wasdetermined by proximal colonic transit (p<0.05) but not by transitthrough the distal colon (p>0.05).
Conclusion—The distal colon retainsnon-absorbable fluid volumes extensively. In our model transit throughthe distal colon—but not the proximal colon—determined the time atwhich diarrhoea occurred.

Keywords:osmotic diarrhoea; colonic transit; storagecapacity; colonic scintigraphy

     

Colorectal neoplasm detection using virtual colonoscopy: a feasibility study

Background—Virtual colonoscopy is a potentiallypowerful tool for non-invasive colorectal evaluation. In vitro studieshave established its accuracy in simulated polyp detection but little data exist regarding its use in clinical practice.
Aims—To evaluate the ability of virtualcolonoscopy to detect colorectal cancers and polyps in patients withendoscopically proven colorectal neoplasms and to correlate thefindings of virtual colonoscopy with those of conventional colonoscopy,surgery, and histopathology.
Patients—Thirty eight patients with endoscopicfindings suggestive of colorectal carcinoma.
Methods—Virtual colonoscopy was performed usingthin section helical computed tomography (CT) of the abdomen and pelvisafter rectal insufflation of room air. Commercially available software was used to generate endoscopic "fly through" examinations of thecolon from the CT data. Results were correlated with the findings ofconventional colonoscopy and with the surgical and histopathological outcome in each case.
Results—Thirty eight pathologically provencolorectal cancers and 23 adenomatous polyps were present. On virtualcolonoscopy, all cancers and all polyps measuring greater than 6 mm insize were identified; there were two false positive reports of polyps. On conventional colonoscopy, there was one false positive report of amalignant sigmoid stricture; four subcentimetre polyps were overlooked.Virtual colonoscopy enabled visualisation of the entire colon in 35 patients; conventional colonoscopy was incomplete in 14 patients.Virtual colonoscopy correctly localised all 38cancers, compared with32 using conventional colonoscopy.
Conclusion—Virtual colonoscopy is a feasiblemethod for evaluating the colon; it may have role in diagnosis ofcolorectal cancer and polyps.

Keywords:colonic neoplasms; computed tomography; computersimulation

     

Heterogeneity in responses by primary adult human colonic epithelial cells to purified enterotoxin of Bacteroides fragilis

Background—Enterotoxigenic strains ofBacteroides fragilis (ETBF) have been implicated indiarrhoeal illness in livestock and children, but their role in adulthuman colonic disease is unknown.
Aims—To investigate responses by primary adulthuman colonic epithelial cells to purified B fragilistoxin (BFT).
Methods—BFT was purified from culture supernatantof a highly toxigenic strain of ETBF. Morphological changes to primarycolonic epithelial cells, in response to purified BFT, were studied in organ culture of colonic biopsy specimens from 15adults.
Results—BFT induced epithelial cell cytotoxicityin colonic biopsy specimens from 12/15 subjects. The BFT inducedmorphological changes were characterised by epithelial cell rounding,separation from adjacent cells, and detachment from the basementmembrane. In severely affected specimens, almost all the epithelialcells were affected. There was heterogeneity between subjects in the rate at which BFT induced epithelial cell cytotoxicity occurred. Furthermore, in colonic biopsy specimens from three subjects, exposureto BFT did not induce any significant morphological changes toepithelial cells.
Conclusion—BFT is capable of inducingcytotoxicity in primary adult human colonic epithelial cells. Such aneffect of ETBF derived BFT on epithelial cells in the colon in vivowould be expected to lead to mucosal inflammation and diarrhoea.Heterogeneity in responses by primary colonocytes probably reflects theoutcome of host-BFT interactions. Such interactions in vivo coulddetermine the occurrence of colonic disease in some individuals but not others.

Keywords:Bacteroides fragilis; enterotoxin; epithelial cells; apoptosis

     

Rectal cell proliferation and colon cancer risk in patients with hypergastrinaemia

Background—The influence of gastrin on the colonicmucosa is still uncertain. Some authors have suggested a stimulatingeffect on the growth of normal and malignant colonic epithelium, while others have shown no association between gastrin and neoplastic development.
Aims—To evaluate the effect of gastrin oncolorectal cell proliferation, patients with chronic endogenoushypergastrinaemia underwent proctoscopy. Biopsy specimens were taken inorder to study rectal cell kinetics.
Patients and controls—Ten patients with chronicautoimmune gastritis (CAG), six patients with Zollinger-Ellisonsyndrome (ZES), and 16 hospital controls took part in this study.Patients with CAG and ZES had basal serum gastrin concentrationssignificantly higher than controls (p<0.001).
Methods—Immunohistochemistry was performed on 3 µm sections of rectal biopsy specimens incubated with5'-bromodeoxyuridine.
Results—The percentage of proliferating cells inthe entire crypts (overall labelling index) was similar in all thegroups. However, the labelling frequency in the upper two fifths of the glands (ϕh value) was significantly higher in patients with CAG orZES compared with controls (p<0.01 in both patient groups versus controls).
Conclusions—Endogenous hypergastrinaemia isassociated with rectal cell proliferation defects, similar to thoseobserved in conditions at high risk for colon cancer. The effect of theincreased serum concentrations of gastrin on the colorectal mucosaafter treatment with drugs inhibiting gastric acid secretion should be investigated.

     

HIV enteropathy: comparative morphometry of the jejunal mucosa of HIV infected patients resident in the United Kingdom and Uganda

Aims—To compare jejunal mucosalmorphometry in HIV infected patients resident in London and Uganda.
Patients—Twenty HIV positivepatients from London and 16 from Uganda were studied, and compared withHIV negative control subjects from both sites.
Methods—Stools and biopsy specimenswere examined for enteropathogens. Surface area to volume (S:V) ratiowas estimated morphometrically, mean crypt length of jejunal biopsyspecimens was measured, and HIV infected cells detectedimmunohistochemically were quantified.
Results—Enteric pathogens weredetected in none of the London patients, and in three Ugandan patients.S:V ratio was lower, and mean crypt length higher, in the specimens ofLondon patients than in normal subjects, but there was no difference inS:V ratio or mean crypt length between Ugandan patients and controls. A negative correlation was present between S:V ratio and mean crypt length in all biopsy specimens analysed. HIV infected cells were detected only in lamina propria.
Conclusion—Infection of cells inthe lamina propria of the jejunum with HIV stimulates crypt cellproliferation, and a fall in villous surface area. The mucosal responseto HIV is masked by other pathogens in the African environment.

Keywords:HIV; jejunum; AIDS; enteropathy

     

Dietary fibre and intestinal microflora: effects on intestinal morphometry and crypt branching

^a Anatomy Department, Medical Biology Centre, Queen's University of Belfast, ^b Robert Gordon University, Kepplestone, Aberdeen, ^c Imperial Cancer Research Fund, Histopathology Unit, Lincoln's Inn Fields, London

Correspondence to: Dr R A Goodlad, Imperial Cancer Research Fund, 35-43 Lincoln's Inn Fields, London WC2A 3PN, UK.

Accepted for publication 19 January 1998

Background—Fermentable dietary fibre has many effects on the gastrointestinal tract. One is to alter epithelial crypt cell proliferation, especially in the colon. A discrepancy between epithelial cell production rates and intestinal weights has been noted previously: crypt cell production rates only increase if bacterial fermentation occurs, but intestinal wet weight can increase in the same animals without bacterial fermentation of fibre.
Aims—To quantify intestinal cell populations in order to resolve the above paradox.
Methods—Conventional and germ-free rats were fed fibre-free or fibre supplemented diets and their intestines were quantified by morphometry.
Results—There was evidence of fibre associated muscle hypertrophy in the colon, but the main effect of fibre was an increase in the number of crypts per circumference and also the number of branched crypts in the proximal colon in both groups. There was also a large increase in the number of branched crypts in the mid colon of the germ-free rats (both fibre-free and fibre supplemented). Fibre had a direct (bacteria independent) effect on goblet cells in the small intestine and a direct effect on the goblet cells in the colon, which was attenuated by the presence of bacteria. There was a notable decline in the number of enteroendocrine cells in the small intestine of the germ-free animals.
Conclusions—Fibre has several direct and indirect effects on the gut. In the proximal colon it can directly increase the number of crypts present. This provides a means for increasing intestinal mass in addition to intestinal crypt cell production.
(GUT 1998;:799-806)

Keywords: fibre;  fermentation;  microflora;  mucus;  intestine;  epithelium

     

Detection of anti-colon antibodies in inflammatory bowel disease using human cultured colonic cells

Background—Investigationof anti-colon antibodies may be simplified if a sensitive method andhomogeneous source of antigen were available.
Aims—To examine theanti-colon antibody response using human colonic carcinoma cell linesas antigen.
Subjects—Patients withinflammatory bowel disease and other gastrointestinal disorders andhealthy controls were studied.
Methods—Comparativeenzyme linked immunosorbent assays (ELISAs) were performed to assessthe value of whole Caco-2, HT-29, and LS-180 cells as antigen. Theantigenic determinants of the immune response were characterised bywestern blot analysis.
Results—Serademonstrated immunoreactivity against each of the cell lines, butdifferent epitopes were recognised. Applying whole Caco-2 cells asantigen in an ELISA, the prevalence of anti-colon antibodies wassignificantly greater in patients with ulcerative colitis (36%) thanCrohn's disease (13%), other gastrointestinal disorders (13%) andhealthy controls (0) (p<0.05). The immune response was not associatedwith one predominant antigen.
Conclusions—Fixedwhole cell ELISA is a simple and feasible method for studying theanti-colon antibody response. This response is non-specific, beingdirected against multiple antigens, and is likely to be anepiphenomenon of inflammatory bowel disease, more so for ulcerativecolitis than Crohn's disease.

Keywords:anti-colon antibodies; inflammatory boweldisease

     

Folate depletion impairs DNA excision repair in the colon of the rat

Background/Aims—Diminishedfolate status appears to promote colonic carcinogenesis by, as of yet,undefined mechanisms. Impaired DNA repair plays a significant role inthe evolution of many colon cancers. Since folate is essential for thede novo synthesis of nucleotides and sincefolate depletion has previously been associated with excessive DNAstrand breaks, it was hypothesised that folate depletion may impair DNArepair. Studies were therefore performed to examine whether folatedepletion affects the two major categories of DNA repair.
Methods—Study 1: eightweanling male Sprague-Dawley rats were fed on diets containing either 0 or 8 mg folate/kg diet with 1% succinylsulphathiazole for four weeks.After viable colonocytes had been harvested, DNA excision repair wasevaluated by a single cell gel electrophoresis assay. Study 2: eighteenanimals were fed on similar diets for five weeks. Also in study 2, 18 additional rats were fed on the same defined diet withoutsuccinylsulphathiazole for 15 weeks. Weekly injections with theprocarcinogen, 1,2-dimethylhydrazine (20 mg base/kg), were administeredto the latter group of animals. Five microsatellite loci from differentchromosomes were investigated for instability in hepatic and colonic DNA.
Results—In study 1, asignificantly retarded rate of DNA excision repair was observed in thefolate deficient colonocytes compared with controls (p<0.05). In study2, there was no evidence of instability at the five microsatellite lociassociated with either short or long term folate depletion.
Conclusions—Folatedeficiency impairs DNA excision repair in rat colonic mucosa; a similardegree of deficiency, even when administered in conjunction with acolonic carcinogen, did not produce evidence of a widespread defect inmismatch repair.

Keywords:folate; colon cancer; DNA repair; single cell gelelectrophoresis; microsatellite instability; rat

     

Reduced susceptibility of mice overexpressing transforming growth factor α to dextran sodium sulphate induced colitis

Background—Transforminggrowth factor α (TGF-α) knockout mice have increased susceptibilityto dextran sodium sulphate (DSS) induced colitis.
Aim—To substantiatethe findings that TGF-α is a key mediator of colonic mucosalprotection and/or repair mechanisms by evaluating the susceptibility ofmice overexpressing TGF-α to DSS induced colitis.
Methods—TGF-αoverexpression was induced in transgenic mice by ZnSO₄administration in drinking water (TG+). Three groups were used ascontrols: one transgenic group without ZnSO₄ administration (TG−), and two non-transgenic littermate groups receivingZnSO₄ (Non-TG+) or only water (Non-TG−). Acute colitiswas induced in all groups by administration of DSS (5%, w/v) indrinking water for six days ad libitum.
Results—About 35-39%of the entire colonic mucosa was destroyed in Non-TG−, Non-TG+, andTG− animals compared with 9% in TG+ mice. The crypt damage score was18.7 (0.9), 18.2 (1.0), 18.9(0.8), and 6.8 (1.5) (means (SEM)) inNon-TG−, Non-TG+, TG−, and TG+ mice respectively. Mucin andbromodeoxyuridine staining were markedly enhanced in colons of TG+ micecompared with controls, indicating increased mucosal protection and regeneration.
Conclusions—Thesignificantly reduced susceptibility of mice overexpressing TGF-α toDSS further substantiates that endogenous TGF-α is a pivotal mediatorof protection and/or healing mechanisms in the colon.

Keywords:transforming growth factor α; epidermal growthfactor; dextran sodium sulphate; colitis; inflammatory bowel disease; transgenic mice

     

Macromolecular transport across the rabbit proximal and distal colon

Background—Although many studieshave investigated macromolecular uptake in the stomach and smallintestine, little is known about macromolecular uptake in the colon.
Aims—To investigate the mechanismsinvolved in the transport of large antigenically intact macromoleculesacross the proximal and distal colonic epithelium in the rabbit.
Methods—The mucosal to serosalmovement of bovine serum albumin (BSA) was examined in modified Ussingchambers under short circuited conditions. The mucosal surface wasexposed to varying concentrations of BSA, and after a 50 minuteequilibration period, the mucosal to serosal flux of immunologicallyintact BSA was determined by ELISA. Total BSA flux was determined by the transport of radiolabelled ¹²⁵I-BSA.
Results—Intact BSA transport inproximal and distal colonic tissue showed saturable kinetics. IntactBSA transport in the proximal and distal segment was 7% and 2% of thetotal ¹²⁵I-BSA flux respectively. Immunologically intactBSA transport in the distal segment was significantly less than that inthe proximal segment. Intact BSA transport in the proximal colon was significantly reduced following treatment with sodium fluoride, colchicine, and tetrodotoxin. Cholinergic blockade had no effect on theuptake of intact BSA.
Conclusion—The findings indicatethat the transport of intact macromolecules across the proximal anddistal large intestine is a saturable process. Further, intact BSAtransport in the proximal colon is an energy dependent process thatutilises microtubules and is regulated by the enteric nervous system.

     

Increased state of activation of CD4 positive T cells and elevated interferon γ production in pouchitis

Background—Immunoregulatory abnormalities of Tcells might be of importance in the pathogenesis of pouchitis afterileoanal pouch anastomosis (IAP).
Aims—To characterise T cell subsets, their stateof activation, and production of cytokines in inflamed and non-inflamedpouches in patients with ulcerative colitis (UC) and familialadenomatous polyposis (FAP). The influence of T cell activation onmucosal transformation was also studied.
Patients—Mucosal biopsy specimens were taken from42 patients with IAP (33 with UC and nine with FAP).
Methods—Mononuclear cells were isolated bystandard techniques and characterised by three colour flow cytometry.Interferon γ (IFN-γ) production was studied using the ELISPOT technique.
Results—In patients with UC with pouchitis therewas a significant increase in the CD4:CD8 ratio, expression ofactivation markers on CD3+ cells, and number of IFNγ producingmononuclear cells compared with patients with UC without pouchitis(CD4:CD8 ratio 1.3 (range 0.7-2.7) versus 0.6 (0.1-1.0), p=0.012). Inaddition, a positive correlation between increased crypt depth and thenumber of CD4+ cells (r=0.57) was shown.
Conclusion—The observed increase in activatedmucosal CD4+ T cells and IFN-γ production might lead to mucosaldestruction and crypt hyperplasia as seen in pouchitis.

Keywords:pouchitis; T cell activation; mucosaltransformation

     

Increasing butyrate concentration in the distal colon by accelerating intestinal transit

Background—Populations at low risk of coloniccancer consume large amounts of fibre and starch and pass acid, bulkystools. One short chain fatty acid (SCFA), butyrate, is the colon'smain energy source and inhibits malignant transformation in vitro.
Aim—To test the hypothesis that altering colonictransit rate alters colonic pH and the SCFA content of the stools.
Patients—Thirteen healthy adults recruited by advertisement.
Methods—Volunteers consumed, in turn, wheat bran,senna and loperamide, each for nine days with a two week washout period between study periods, dietary intake being unchanged. Before, and inthe last four days of each intervention, whole gut transit time (WGTT),defaecation frequency, stool form, stool β-glucuronidase activity,stool pH, stool SCFA concentrations and intracolonic pH (using aradiotelemetry capsule for continuous monitoring) were assessed.
Results—WGTT decreased, stool output and frequencyincreased with wheat bran and senna, vice versa with loperamide. The pH was similar in the distal colon and stool. Distal colonic pH fell withwheat bran and senna and tended to increase with loperamide. FaecalSCFA concentrations, including butyrate, increased with senna and fellwith loperamide. With wheat bran the changes were non-significant,possibly because of the short duration of the study. Baseline WGTTcorrelated with faecal SCFA concentration (r=−0.511,p=0.001), with faecal butyrate (r=−0.577, p<0.001) andwith distal colonic pH (r=0.359, p=0.029).
Conclusion—Bowel transit rate is a determinant ofstool SCFA concentration including butyrate and distal colonic pH. This may explain the inter-relations between colonic cancer, dietary fibreintake, stool output, and stool pH.

     

Is there an excess risk for colorectal cancer in patients with ulcerative colitis and concomitant primary sclerosing cholangitis? A population based study

Background—Patients with ulcerative colitis havean increased risk of colorectal cancer. Duration, age, and extent ofthe disease at diagnosis are the only established risk factors.Patients with ulcerative colitis and concomitant primary sclerosingcholangitis (PSC) have been reported to have a higher frequency ofcolonic DNA aneuploidy and/or dysplasia than expected, findingsindicating an increased risk of colorectal cancer compared with otherpatients with ulcerative colitis.
Methods—A population based cohort consisting of125 patients with a verified diagnosis of PSC was followed up bylinkage to the Swedish Cancer Registry for the occurrence of colorectal cancer.
Results—There were 12 colorectal cancers. Sixcancers were diagnosed prior to the diagnosis of PSC. Among the 104 patients with an intact colon at the time of the diagnosis of PSC there was a cumulative risk for colorectal cancer of 16% after 10 years. Among the 58 patients with a diagnosis of ulcerative colitis and colorectal cancer prior to the diagnosis of PSC, there were five colorectal cancers corresponding to a cumulative risk of 25% after 10years.
Conclusions—Patients with ulcerative colitis andconcomitant PSC seem to constitute a subgroup with a high risk forcolorectal cancer.

     

Mast cell mediated ion transport in intestine from patients with and without inflammatory bowel disease

Background—Mast cells have been shown to regulateintestinal ion transport in animal models and normal human colon buttheir physiological role in human intestinal inflammatory disorders is unknown.
Aims—To examine mast cell regulation of iontransport in inflammatory bowel disease (IBD).
Subjects and methods—Small and large intestinewas obtained from patients with and without IBD undergoing surgicalresection. Short circuit current (Isc) responses to rabbitantihuman IgE, histamine, and electrical stimulation were measured inUssing chambers. Specimens were also examined for mast cell numbers and degree of inflammation.
Results—Isc responses to anti-IgEand histamine were smaller in magnitude in IBD compared with non-IBDtissues. In all tissues, anti-IgE Isc responses werereduced by about 80% in chloride free buffer. The histamineH₁ receptor antagonist, pyrilamine, decreased anti-IgEresponses in non-IBD tissues. Greater inhibition with pyrilamine wasseen in IBD small intestine but its effect was less in IBD colon.Histamine pretreatment of non-IBD control tissues reduced anti-IgEresponses to levels seen in IBD colon but had no effect in smallintestine. Mast cell numbers were greater in IBD compared with non-IBDsmall intestine while no differences were observed between the colonicgroups. Isc responses to anti-IgE were not correlated withthe degree of mucosal inflammation.
Conclusions—This study provides further evidencethat mast cells are capable of mediating alterations of ion transportin human gut but that this regulatory role may be altered in IBD. Thedata suggest that prior activation of mast cells with release ofhistamine may account for the reduced secretory response to anti-IgEobserved in IBD colonic tissues.

Keywords:mast cells; intestine; ion transport; histamine; ulcerative colitis; Crohn's disease

     

Spontaneous secretion of interferon γ and interleukin 4 by human intraepithelial and lamina propria gut lymphocytes

Background—Cytokines secreted by intestinal Tlymphocytes probably play a critical role in regulation of the gutassociated immune responses.
Aims—To quantify interferon γ (IFN-γ) andinterleukin 4 (IL-4) secreting cells (SC) among human intraepithelial(IEL) and lamina propria (LPL) lymphocytes from the duodenum and rightcolon in non-pathological situations and in the absence of in vitro stimulation.
Patients—Duodenal and right colonic biopsyspecimens were obtained from patients with no inflammation of theintestinal mucosa.
Methods—Intraepithelial and lamina propria cellsuspensions were assayed for numbers of cells spontaneously secretingIFN-γ and IL-4 by a two site reverse enzyme linked immunospottechnique (ELISPOT).
Results—The relatively high proportion ofduodenal lymphocytes spontaneously secreting IFN-γ (IEL 3.6%; LPL1.9%) and IL-4 (IEL 1.3%; LPL 0.7%) contrasted with the very lownumbers of spontaneously IFN-γ SC and the absence of spontaneouslyIL-4 SC among peripheral blood mononuclear cells. In the basal state,both IFN-γ and IL-4 were mainly produced by CD4⁺ cells.Within the colon, only 0.2% of IEL and LPL secreted IFN-γ in thebasal state, and 0.1% secreted IL-4.
Conclusions—Compared with peripheral lymphocytessubstantial proportions of intestinal epithelial and lamina proprialymphocytes spontaneously secrete IFN-γ and/or IL-4. These cytokinesare probably involved in the normal homoeostasis of the humanintestinal mucosa. Disturbances in their secretion could play a role inthe pathogenesis of gastrointestinal diseases.

     

Medium term effects of a new 5HT3 antagonist, alosetron, in patients with carcinoid diarrhoea

Background—Carcinoid diarrhoea is associated withrapid small bowel and proximal colonic transit. Intravenousadministration of a serotonin type 3 receptor (5HT₃)antagonist restores postprandial colonic tone towards normal incarcinoid patients.
Aims—To evaluate the medium term effects of anoral 5HT₃ antagonist, alosetron, on symptoms, stool fat,and transit in patients with carcinoid diarrhoea.
Methods—In 27 patients with carcinoid diarrhoea,symptoms were recorded daily and gastrointestinal transit was measuredby scintigraphy in a three dose (0.1, 0.5, 2.0 mg, twice daily), randomised (1:1:1), parallel group, four week study. Placebo was givenduring the first week. Loperamide (2 mg capsules) was used as rescue medication.
Results—There were numerical improvements inmedian diarrhoea score, stool weight, loperamide use, and overallcolonic transit at four hours, but no overall significant drug effectwas shown. Alosetron reduced the proximal colon emptying rate (p<0.05in 20 evaluable comparisons), but did not significantly alter small bowel transit.
Conclusions—Alosetron retardation of proximalcolonic emptying in patients with carcinoid diarrhoea confirms thepotential role of a 5HT₃ mechanism in this disorder. Dosesof alosetron higher than 2.0 mg twice daily will be required forsymptomatic benefit in carcinoid diarrhoea.

Keywords:carcinoid diarrhoea; alosetron; serotoninergicagents; antagonist; colonic transit