Effect of gender on the manifestations of celiac disease: Evidence for greater malabsorption in men

Background: Nitric oxide (NO) produced in excess by the inflamed human colon is generally considered a pathway of mucosal damage. In an attempt to quantify colonic mucosal production of NO in various forms of colitis we performed 'steady-state' gas perfusion of whole colon in 11 patients with ulcerative colitis, 10 patients with collagenous colitis and 20 controls with uninflamed mucosa. Methods: The tip of a Teflon tube was placed in the caecum during colonoscopy. Subsequently, argon was infused at a constant rate for 70-180 min. Argon and NO in gas sampled from the rectum were measured by neutron activation analysis and the chemiluminescence technique, respectively. Results: The use of argon as a marker of colonic NO output was justified by complete recovery (96% ± 2; mean ± s- x ; n = 5) of argon in gas collected from the rectum and a constant output of NO at varying perfusion rates (25, 50 and 75 ml/min; coefficient of variation 21%; n = 6). In patients with ulcerative colitis, colonic output of NO was 10-fold higher ( P < 0.001) than in controls and positively correlated ( P < 0.01) to indices of disease activity. In patients with collagenous colitis, colonic output of NO was 50-fold higher ( P < 0.01) than in controls during periods with watery diarrhoea ( n = 6), but within the range observed in ulcerative colitis in the absence of diarrhoea ( n = 4). Conclusions: Argon gas perfusion of whole colon using chemiluminescence technique for measurement of NO is a reliable method for quantification of colonic mucosal NO production. Increased colonic production of NO in collagenous colitis, which exceeds the output observed even in extensive ulcerative colitis, militates against the theory that NO per se is a cause of mucosal injury.     

Expression of nitric oxide synthases and effects of L-arginine and L-NMMA on nitric oxide production and fluid transport in collagenous colitis

BACKGROUND AND AIMS: Luminal nitric oxide (NO) is greatly increased in the colon of patients with collagenous and ulcerative colitis. To define the source and consequence of enhanced NO production we have studied expression of NO synthase (NOS) isoforms and nitrotyrosine in mucosal biopsies from these patients. In addition, effects on colonic fluid transfer caused by manipulating the substrate of NOS were studied in patients with collagenous colitis. PATIENTS: Eight patients with collagenous colitis, nine with active ulcerative colitis, and 10 with uninflamed bowel were included. METHODS: Expression of NOS isoforms was quantified by western blotting. Inducible NOS (iNOS) and nitrotyrosine were localised by immunohistochemistry. Modulation of NOS activity by topical N(G)-monomethyl-L-arginine (L-NMMA) or L-arginine was assessed during perfusion of whole colon. Plasma and perfusate nitrite/nitrate (NOx) was measured by Griess' reaction. RESULTS: Both in collagenous and ulcerative colitis, expression of iNOS was 10(2)-10(3) higher (p<0.001) than in uninflamed bowel and localised primarily to the epithelium. Endothelial NOS was evenly expressed in all groups while neuronal NOS was undetectable. Nitrotyrosine was markedly expressed in active ulcerative colitis but rarely detected in collagenous colitis and never in uninflamed bowel. In collagenous colitis, the output of NOx was markedly increased compared with uninflamed bowel (283 (58) v <37 nmol/min; p<0.01) and fluid was net secreted. L-NMMA reduced the output of NOx by 13-66% (95% confidence intervals) and secretion of fluid by 25-109% whereas L-arginine increased the output of NOx by 3-39% and secretion of fluid by 15-93%. CONCLUSIONS: In collagenous colitis, as opposed to ulcerative colitis, upregulation of iNOS occurs in the absence of nitrotyrosine formation and mucosal damage. Excess generation of NO may be the primary cause of diarrhoea in this condition.     

Expression of inducible nitric oxide synthase and effects of L-arginine on colonic nitric oxide production and fluid transport in patients with "minimal colitis"

OBJECTIVE: Some patients with idiopathic, chronic diarrhoea have minimal, non-specific colonic inflammation. As nitric oxide (NO) acts as a secretagogue in the colon, we studied the expression of inducible NO synthase (iNOS) in mucosal biopsies and the effects of NOS stimulation on colonic transfer of fluid and output of NO in patients with "minimal colitis". MATERIAL AND METHODS: Twelve patients with idiopathic, chronic diarrhoea and "minimal colitis" and 6 healthy volunteers were included in the study. Expression of iNOS in colonic mucosal biopsies was quantified by Western blot analysis and localized by immunohistochemistry. The effects of topical L-arginine or placebo on colonic net fluid transfer and nitrite/nitrate (NOx) output were assessed during "steady state" perfusion of the whole colon. Concentrations of NOx were measured by Griess' assay. RESULTS: The expression of iNOS was increased 10-fold (p<0.01) in patients with "minimal colitis" compared with that in healthy volunteers and localized to the colonic epithelium. Colonic absorption of fluid was impaired (mean (SEM) 1.5 (0.2) versus 3.0 (0.2) ml/min, p<0.001) and the output of NOx was increased (47 (4) nmol/min versus <37 nmol/min, p<0.05) in patients with "minimal colitis" compared with that in healthy volunteers. Luminal L-arginine (20 mM) reduced colonic absorption of fluid in both groups (95% confidence intervals (CIs) 21-50% in patients with "minimal colitis" versus 4-18% in healthy volunteers), but an increase in NOx output was detectable only in the group of patients (8-106%). In time control experiments, colonic net transfer rates of fluid and outputs of NOx were unaffected by placebo. CONCLUSIONS: In patients with idiopathic, chronic diarrhoea and histopathological evidence of "minimal colitis", colonic absorption of fluid is impaired, while epithelial expression of iNOS and mucosal production of NO is enhanced. It could be speculated that NO in excess contributes to the diarrhoea observed in "minimal colitis".     

Different distribution of mast cells and macrophages in colonic mucosa of patients with collagenous colitis and inflammatory bowel disease

BACKGROUND/AIMS: Chronic inflammatory cells in colonic mucosa is a histopathologic feature in patients with collagenous colitis and inflammatory bowel disease. The aim of this study was to compare the distribution of mast cells and macrophages in the colonic mucosa of patients with collagenous colitis, Crohn's disease, and ulcerative colitis. METHODOLOGY: Patients with histologically confirmed collagenous colitis (n = 13), Crohn's disease (n = 20) or ulcerative colitis (n = 20) and normal control patients (n = 20) were included in this study. Biopsy specimens were obtained from the sigmoid colon of each patient, and immunostained using antibodies to tryptase (AA1) and CD68. The number of mast cells and macrophages located in upper and lower part of the lamina propria was determined. RESULTS: The number of mast cells in the upper part of lamina propria in patients with collagenous colitis (286 +/- 89/mm2, mean +/- SD), Crohn's disease (330 +/- 84/mm2) and ulcerative colitis (355 +/- 90/mm2), was higher than normal controls (201 +/- 44/mm2). The number of mast cells in the lower part of lamina propria in patients with Crohn's disease (345 +/- 87/mm2) and ulcerative colitis (363 +/- 86/mm2) was higher than collagenous colitis (266 +/- 63/mm2) and normal controls (309 +/- 60/mm2). The number of macrophages in the lower part of lamina propria in patients with Crohn's disease (330 +/- 63/mm2) and ulcerative colitis (301 +/- 60/mm2) was higher than in collagenous colitis (247 +/- 46/mm2) and normal controls (242 +/- 52/mm2), although there were no significant differences in the number of macrophages present in the upper part of the lamina propria among the four groups. CONCLUSIONS: Our data showed the presence of a different distribution of mast cells and macrophages in collagenous colitis and inflammatory bowel disease, and these suggest that because mucosal mast cells have been implicated in the development of Th2 response collagenous colitis is more of a Th2 type reaction rather than Th1.     

Intraluminal excretion of PAF,lysoPAF, and acetylhydrolase in patients with ulcerative colitis

PAF-acether (PAF) is a phospholipid synthesized by numerous inflammatory cells. PAF can produce several pathological changes in various organs, especially in the colon. In animals PAF causes colonic ulceration and inflammation, which are similar to the anatomic lesions seen in human ulcerative colitis. The aim of this study was to measurein vivo colonic production of PAF in active ulcerative colitis using a modified colonic perfusion method. Ten patients with active ulcerative colitis and six control patients were investigated. A colonic segment was continuously perfused with a buffer and the liquid was recovered 20 cm distally, after a 45-min period of equilibration, at 20-min intervals. PAF, lysoPAF, and acetylhydrolase were measured in the colonic samples. PAF and lysoPAF outputs were significantly higher in patients with active ulcerative colitis compared to controls patients. There was a significant correlation between colonic PAF output and, respectively, macroscopic mucosal lesions and myeloperoxidase colonic output. We thus conclude: (1) the colonic perfusion method allowsin vivo study of the metabolism of PAF during ulcerative colitis and could also be used to study the efficiency of PAF antagonists in UC; and (2) colonic production of PAF is increased during ulcerative colitis and correlated to local injury and inflammation. Whether or not PAF plays a role in the pathogenesis of ulcerative colitis remains open for further investigations.     

Metachronous occurrence of collagenous colitis and ulcerative colitis.

Collagenous colitis and ulcerative colitis are distinct disorders. A 67 year old woman with clinical and histological evidence of collagenous colitis had an abrupt symptomatic exacerbation while taking anti-inflammatory treatment with sulphasalazine and prednisone. Repeat colorectal endoscopy showed active mucosal inflammation and colonic biopsy specimens were consistent with active ulcerative colitis. After bowel rest, total parenteral nutrition, intensification of the anti-inflammatory regimen, and withdrawal of non-steroidal anti-inflammatory drugs (which she had taken continuously for osteoarthritis) diarrhoea abated. Colorectal biopsy specimens obtained when the patient's symptoms had improved showed inactive ulcerative colitis with no evidence of collagenous colitis. This may be the first case to be reported of the metachronous association of collagenous and ulcerative colitis.     

Glycoprotein composition of colonic mucosa. Specific alterations in ulcerative colitis

A micromethod has been developed to permit determination of human colonic mucin glycoprotein heterogeneity in biopsy specimens of colonic mucosa. Sialic acid, galactose, and galactosamine residues of oligosaccharide side chains from colonic glycoproteins were radiolabeled by combined metaperiodate and galactose oxidase treatment followed by sodium borotritide reduction. Mucin glycoproteins were separated from nonmucin components by mini-Sepharose 4B column chromatography. Subsequent chromatography of labeled mucin of normal controls (n = 15) on diethylaminoethyl-cellulose demonstrated at least six labeled mucin species. Labeled mucin species I-VI were found to cochromatograph with corresponding unlabeled mucin species prepared from large surgical specimens. An identical mucin profile was observed in normal biopsy specimens from rectum (n = 5), sigmoid (n = 10), transverse (n = 5), and ascending colon (n = 4). However, mucin profiles from sigmoid mucosa of patients with ulcerative colitis (n = 14) demonstrated a selective decrease in mucin species IV, which was also present in specimens from uninvolved proximal colon (n = 7). This finding persisted in patients who had a subsequent biopsy at times of clinical and histologic remission (n = 8). In addition, colonic mucin from samples of ulcerative colitis patients in remission had a relative decrease in mucin fraction III and an increase in fraction V when compared to patients with active disease. Normal mucin profiles were found in a variety of colonic disease controls including Crohn's (n = 9), ischemic (n = 4), infectious (n = 8), and radiation (n = 3) colitis. These observations indicate the presence of a relatively uniform mucin profile throughout the normal colon and substantiate the association of specific alterations in colonic mucin with ulcerative colitis.     

Effect of intravenous L-NMMA on nitric oxide production in collagenous colitis

BACKGROUND: Nitric oxide (NO) is greatly increased in the colon of patients with inflammatory bowel disease of different aetiology, including collagenous colitis. In man, NO can be generated from NO synthases as well as from non-enzymatic sources. The source of the NO found in luminal intestinal gas has not been exactly pinpointed. We investigated the effect of the NO synthase inhibitor L-NMMA on intestinal concentrations of NO in patients with clinically active collagenous colitis. In addition, we measured NO levels from the respiratory tract. METHODS: Ten patients with active collagenous colitis were studied. NO levels were measured from the respiratory tract and in the rectum before and after i.v. administration of L-NMMA (7.5 mg/kg) using a chemiluminescence method. RESULTS: Airway NO release decreased markedly, and mean arterial blood pressure increased in all patients following L-NMMA treatment. Basal rectal NO levels were high (median > 10000 ppb) and decreased markedly in 5 patients after L-NMMA. In contrast, NO levels remained completely unchanged or even increased in the other 5 patients. CONCLUSION: Rectal levels of NO are greatly increased in patients with symptomatic collagenous colitis. Intravenous administration of an NO synthase inhibitor reduced rectal NO only in half of the patients despite clear evidence of effective systemic NO synthase inhibition. This could indicate alternative NOS-independent sources of intestinal NO in this disease.     

Mucosal blood flow and generation of superoxide in rat experimental colitis induced by succinic acid

As we consider succinic acid to be an exacerbating factor in ulcerative colitis, we investigated its influence on rat colonic mucosa in terms of mucosal blood flow and superoxide generation. We measured mucosal blood flow by the hydrogen gas clearance method and superoxide generation by the chemiluminescence method, and observed histopathological findings to determine the effects of succinic acid. After the instillation of succinic acid of any concentration tested to the colon, mucosal blood flow decreased. Histopathologically, the higher the concentration of succinic acid, the greater was the erosion formation in the colonic mucosa, while significant polymorpho-nuclear cell infiltration and superoxide generation from colon tissue were observed with 0.01% succinic acid compared with higher or lower concentrations. Succinic acid, at fecal concentrations found in active stage ulcerative colitis, appears to be implicated in mucosal injury, mediated by a decrease in colonic mucosal blood flow and infiltration of superoxide-generating polymorpho-nuclear cells into the mucosa.     

Colonic mucosal tears in collagenous colitis

In general, the colonic mucosa is macroscopically normal in collagenous colitis, although minor, non-specific abnormalities may be found. Significant endoscopic abnormalities, “mucosal tears” representing longitudinal mucosal lacerations, have been reported in a few patients with collagenous colitis. We report the cases of three women with collagenous colitis and mucosal tears detected at the index colonoscopy in order to illustrate the endoscopic characteristics and review the literature. Including the present cases, a total of 12 patients with mucosal tears and collagenous colitis have been reported. In 10 patients, the mucosal lacerations involved the ascending or the transverse colon. Three of the 12 patients had a colonic perforation immediately after the colonoscopy. The colonoscopist should be aware that the risk of perforation is likely to be increased when mucosal tears are present.     

Colonic mucosal tears in collagenous colitis

In general, the colonic mucosa is macroscopically normal in collagenous colitis, although minor, non-specific abnormalities may be found. Significant endoscopic abnormalities, "mucosal tears" representing longitudinal mucosal lacerations, have been reported in a few patients with collagenous colitis. We report the cases of three women with collagenous colitis and mucosal tears detected at the index colonoscopy in order to illustrate the endoscopic characteristics and review the literature. Including the present cases, a total of 12 patients with mucosal tears and collagenous colitis have been reported. In 10 patients, the mucosal lacerations involved the ascending or the transverse colon. Three of the 12 patients had a colonic perforation immediately after the colonoscopy. The colonoscopist should be aware that the risk of perforation is likely to be increased when mucosal tears are present.     

Increased group II phospholipase A2 in colonic mucosa of patients with Crohn's disease and ulcerative colitis.

The immunochemical protein content of group II phospholipase A2 (PLA2) and PLA2 enzymatic activity were measured for colonic mucosal biopsy samples obtained from patients with either Crohn's disease of the colon or ulcerative colitis, and control patients without inflammatory bowel disease. Immunoreactive group II PLA2 (IR-PLA2 II) content and PLA2 activity in actively inflamed colonic mucosa of Crohn's disease patients were significantly higher than those in inactively inflamed mucosa of Crohn's disease patients and the colonic mucosa of controls. IR-PLA2 II content and PLA2 activity in severely inflamed mucosa of ulcerative colitis patients were significantly higher than those in the colonic mucosa of the controls. Mucosal PLA2 enzymatic activity was closely correlated with mucosal IR-PLA2 II content in patients with Crohn's disease and ulcerative colitis. These results suggest that an increase in PLA2 enzymatic activity in inflamed colonic mucosa of Crohn's disease and ulcerative colitis was mainly attributed to increased protein content of group II PLA2, and that an increase in mucosal group II PLA2 may be involved in the pathogenesis of intestinal inflammation of Crohn's disease and ulcerative colitis.     

Colonic propulsive and postprandial motor activity in patients with ulcerative colitis in remission

BACKGROUND: Although it is known that colon motility is abnormal in ulcerative colitis, data are still scarce with regard to the underlying mechanisms. Recent evidence suggests that the propulsive activity is highly increased during the active phase of the disease, probably contributing to the diarrhoea. However, data are even scarcer in the quiescent phase of the disease. AIMS: To assess the colonic high-amplitude and low-amplitude propulsive activity and the colonic motor response to eating in patients with ulcerative colitis in remission. PATIENTS AND METHODS: Fourteen patients were recruited, all with the disease in remission as documented by clinical and endoscopic criteria. Twenty-four hour manometric recordings were obtained in these patients, and compared to those of 16 healthy controls. RESULTS: The high-amplitude propagated contractions were similar in both groups (5.8+/-2.6 events in ulcerative colitis patients and 5.5+/-0.8 in controls (P=0.13)), whereas patients tended to display a higher number of low-amplitude propagated events (134.4+/-34 vs. 60.9+/-16 in controls (P=0.058)). No differences were found in the colonic motor response to eating between patients and controls. CONCLUSIONS: Colonic propulsive activity in ulcerative colitis in remission is almost normal, even though the low-amplitude propagated activity tends to be similar to that observed in patients with the irritable bowel syndrome, thus possibly contributing to the persistence of abdominal symptoms in a subgroup of patients.     

Mucosal secretion and expression of basic fibroblast growth factor in patients with collagenous colitis

Objectives: Collagenous colitis (CC), a condition of unknown ethiology and pathophysiology, is characterized by watery diarrhea and increased amounts of collagen in the colonic mucosa. Basic fibroblast growth factor (bFGF) is a potent multifunctional growth factor that stimulates proliferation and differentiation of fibroblasts that was recently detected in high intraluminal concentrations in patients with ulcerative colitis. In this study we examined the secretion and expression of bFGF in the colorectal mucosa of patients with CC.
Methods Ten CC patients and 10 control patients underwent colonoscope-based segmental perfusion of the descending colon and rectum. The concentrations of bFGF in perfusate and serum were determined by immunochemical methods, and the expression of bFGF was analyzed immunohistochemically in biopsy samples from colonic mucosa.
Results The median concentrations of bFGF in perfusates from the descending colon and rectum were increased 4-fold in CC patients compared with control patients. The median concentration of bFGF in serum was not significantly different in patients and controls. Immunohistochemical staining of bFGF was located in the colorectal epithelial cells and in exsudate on the luminal side of these cells. In the lamina propria, inflammatory cells and fibroblasts contained bFGF. There were no differences in the intensity of bFGF staining in surface epithelium or lamina propria between patients and controls.
Conclusion Local investigation of the colorectal mucosa seems to be crucial when studying the pathophysiology of CC. Increased colorectal mucosal secretion of bFGF in patients with CC may promote differentiation of fibroblasts and thereby lead to increased subepithelial collagen deposition.     

Measurement of colonic mucosal concentrations of 5-aminosalicylic acid is useful for estimating its therapeutic efficacy in distal ulcerative colitis: comparison of orally administered mesalamine and sulfasalazine

OBJECTIVES: Oral 5-aminosalicylic acid (5-ASA) preparations have been used frequently in the treatment of ulcerative colitis. However, there have been few reports investigating the relationship between colonic mucosal concentrations of 5-ASA and its clinical efficacy when oral sulfasalazine or 5-ASA compounds were administered. The aim of this study is to compare the mucosal concentrations of 5-ASA ensured by sulfasalazine or mesalamine, and to define the clinical significance of the measurement of 5-ASA concentrations in the treatment of distal ulcerative colitis. MATERIALS AND METHODS: Biopsies were taken from the rectum and sigmoid colon of the oral sulfasalazine group (n = 13) and the slow-release 5-ASA (mesalamine) group with (n = 5) or without (n = 11) rectal administration of 5-ASA. High-pressure liquid chromatography was used to measure the tissue concentrations of 5-ASA and its metabolites. We compared the 5-ASA concentrations of the sulfasalazine group with the mesalamine group. Furthermore, we analyzed the relationship between tissue 5-ASA concentrations and the Disease Activity Index (DAI). RESULTS: The concentrations of 5-ASA and acetyl-5-ASA in the sulfasalazine group were higher than those in the group taking oral mesalamine alone (p < 0.01). The concentration of 5-ASA was much higher in the patients who received oral and rectal mesalamine in an enema than in the patients who had oral mesalamine alone. There was a significant inverse correlation between the DAI and concentrations of 5-ASA in the rectum (r = 0.712, p < 0.001). CONCLUSIONS: We demonstrated that the colonic mucosal concentration of 5-ASA was significantly higher in the sulfasalazine group than in the mesalamine group. Furthermore, the concentrations of mucosal 5-ASA may be a good marker for the estimation of its efficacy in the treatment of ulcerative colitis.     

Greatly increased mucosal nitric oxide in ulcerative colitis determined in situ by a novel nitric oxide-selective microelectrode

Although current nitric oxide (NO) electrodes are simple, selective and sensitive, they are fragile and hard to use in clinical studies of patients. By preparing an improved NO electroneedle that overcomes these defects, we directly measured mucosal NO concentrations in 11 patients (six male, five female; mean 26.0 years old) with ulcerative colitis (UC) and five normal volunteers (three male, two female; mean 28.3 years old) in situ . An electroneedle was inserted into colonic mucosa through a biopsy channel during colonoscopy. The information concerning the concentration of NO generated and the appearances of the colonic mucosa at the same site were obtained simultaneously. In the ulcerative colitis patients, NO concentrations were significantly increased at all 24 mucosal sites tested. These included sites where: there was an absence of visible inflammation (five sites); the mucosa was mildly inflamed (eight sites); the mucosa was moderately inflamed (five sites); or severely inflamed (six sites). The NO concentrations in ulcerative colitis patients were 12–72 times higher than the NO levels in normal controls (10 sites). At the same 10 sites in four ulcerative colitis patients, the high NO concentrations were decreased by 53% after glucocorticoid treatment. These data are consistent with those of previous studies utilizing different NO electrodes. Excess mucosal NO is generated from inducible NO synthase in the inflamed mucosa itself and the invading inflammatory cells. Our results suggested that mucosal NO could be a marker for the extent of inflammation and its various actions correlated with the pathogenesis, natural history and prognosis of UC. Using the NO microelectrode system reported here, the concentration of NO generated can be monitored in real-time while observing the mucosal condition at the same site during endoscopy. This novel NO electrode may contribute to understanding the role of NO in colonic mucosal inflammation.     

Deficiency of colonic telomerase in ulcerative colitis

OBJECTIVE: GI epithelial cells express telomerase, a ribonucleoprotein that prevents telomeric shortening in proliferating cells. Telomerase levels are high in cancer, but little is known about telomerase expression in other diseases. We, therefore, designed experiments to determine telomerase expression in different colonic segments and to compare this with corresponding segments in patients with ulcerative colitis. Colorectal cancers and adenomatous polyps were included as disease controls. METHODS: In total, telomerase expression was determined in colonic tissues obtained from 62 patients. Twenty-five patients had ulcerative colitis, 21 had normal colons, 11 had colorectal cancer, and nine had adenomatous polyps. Endoscopic biopsies were collected prospectively at colonoscopy, processed for telomerase assays (Telomeric Repeat Amplification Protocol), hematoxylin and eosin staining, and scored for inflammation. RESULTS: Telomerase activity is expressed in arbitrary units (median 95% confidence interval). In the normal colon, telomerase activity in the cecum, transverse, sigmoid, and rectum was 255 (171-449), 707 (374-895), 561 (468-1426), and 563 (402-846), respectively. Telomerase was higher in the distal three segments when compared with the cecum (p = 0.005). In ulcerative colitis, there was a marked decrease in telomerase activity in the cecum 152 (59-272), p = 0.04, transverse 180 (129-365), p < 0.001, sigmoid 352 (114-464), p = 0.005, and rectum 180 (70-337), p = 0.001 when compared with normals. Telomerase activity correlated negatively with inflammation (r = -0.32, p = 0.001) and was also decreased in microscopically normal areas. Cancers expressed high levels of telomerase. CONCLUSIONS: Colonic mucosal expression of telomerase is reduced in ulcerative colitis. Levels are low even in microscopically normal mucosa, suggesting that telomerase deficiency may contribute to the pathogenesis of the disease.     

Phospholipase A2 activity of colonic mucosa in patients with ulcerative colitis.

Activation of enzyme phospholipase A2 (EC 3.1.1.4), the major liberator of arachidonic acid, has been proposed as a component in the pathogenesis of inflammatory bowel disease. To test the hypothesis that phospholipase A2 activity is increased in ulcerative colitis, enzyme activity was investigated in colonic biopsies using radiolabelled Escherichia coli as substrate. The study comprised patients with ulcerative colitis (n = 19) and controls without inflammatory bowel disease (n = 7). Ulcerative colitis patients were grouped into those with active disease (n = 8) and those in remission (n = 11) at the time of colonoscopy. No differences were found in mucosal phospholipase A2 activity between patients with active disease, patients in remission and controls. With the present assay we were unable to demonstrate activation of phospholipase A2 as a mechanism in the inflammatory process of ulcerative colitis.     

Vascular Endothelial Growth Factor (VEGF)—A Possible Mediator of Inflammation and Mucosal Permeability in Patients with Collagenous Colitis

Patients with collagenous colitis have watery diarrhea and histopathologically thickened collagen layer with discrete signs of mucosal inflammation. Vascular endothelial growth factor (VEGF) is a potent angiogenic, mitogenic, permeability, and fibrosis enhancing peptide and it was studied by segmental perfusion and immunohistochemistry in patients and controls. The concentrations of VEGF were significantly increased in perfusates from both the descending colon and the rectum in patients compared to controls but this difference was not found in serum. Immunohistochemical staining showed expression of VEGF within colon epithelial cells, inflammatory cells, and fibroblasts in the lamina propria. The intensity of staining in the surface epithelium was not different between patients and controls but in the lamina propria the intensity was significantly higher among controls. Patients with collagenous colitis have increased colorectal mucosal secretion of VEGF, which may lead to albumin leakage and promote fibrosis with deposition of collagen.