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Background: The pathophysiological role of pancreatic digestive hydrolases in intestinal ischemia-reperfusion (I/R) injury is still not clear. Here, we studied whether ischemia-induced injury to the small intestine can be explained by the autodigestion hypothesis., Materials and Methods: Mesenteric I/R was induced in rats by superior mesenteric artery occlusion (90 min) and reopening (120 min). Thirty minutes before superior mesenteric artery occlusion, aprotinin (14.7 mg/kg), orlistat (5 mg/kg), and their combination or α1-proteinase inhibitor (60 mg/kg) were injected into the lumen of the small intestine. Systemic and vital parameters, intestinal microcirculation, and mucosal barrier function were monitored during the observation phase; markers of small intestinal injury, as well as trypsin-, chymotrypsin-, elastase-, and lipase-like activities in intestinal effluates were assessed at the end., Results: The pattern of small intestinal injury correlated inversely with the local alterations in microvascular tissue perfusion and corresponded with the intestinal distribution of trypsin-like activity. Aprotinin almost completely inhibited trypsin-like activity (P < 0.05) and significantly reduced intestinal tissue injury. Combined with orlistat, it also increased the postischemic blood pressure (P < 0.05) but not the intestinal barrier function. Macroscopic as well as the histologic alterations were decreased by α1-proteinase inhibitor, which significantly improved postischemic blood pressure (P < 0.05)., Conclusions: The I/R-induced pattern of small intestinal injury is likely to result from both local differences in tissue ischemia and the digestive activity of migrated pancreatic trypsin. Therefore, administration of aprotinin and orlistat into ischemic small intestines may be a therapeutic option in patients with a poor diagnosis., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Nonsteroidal anti-inflammatory drugs (NSAIDs) can induce intestinal mucosal damage, but the underlying mechanisms remain poorly understood. The present study investigated the effects of celecoxib, etoricoxib, indomethacin, and diclofenac on small bowel integrity in rats. Male rats were treated orally with test drugs for 14 days. Animals were processed for assessment of blood hemoglobin levels and hepatic mitochondrial functions, microscopic evaluation of small intestinal damage, Western blot analysis of cyclooxygenase-1 and -2 (COX-1, COX-2) expression, and assay of malondialdehyde (MDA), myeloperoxidase (MPO), and prostaglandin E2 (PGE2) levels in small intestine. Indomethacin and diclofenac decreased blood hemoglobin levels, whereas etoricoxib and celecoxib were without effects. Celecoxib caused a lower degree of intestinal damage in comparison with the other test drugs. Indomethacin and diclofenac, but not etoricoxib or celecoxib, reduced intestinal PGE2 levels. Test drugs did not modify intestinal COX-1 expression, although they enhanced COX-2, with the exception of celecoxib, which downregulated COX-2. Indomethacin, diclofenac, and etoricoxib altered mitochondrial respiratory parameters, although celecoxib was without effects. Indomethacin or diclofenac increased MDA and MPO levels in both jejunum and ileum. In the jejunum, etoricoxib or celecoxib did not modify such parameters, whereas in the ileum, etoricoxib, but not celecoxib, increased both MDA and MPO levels. These findings suggest that nonselective NSAIDs and etoricoxib can induce enteropathy through a topic action, whereas celecoxib lacks relevant detrimental actions. The selectivity profile of COX-1/COX-2 inhibition by test drugs and the related effects on prostaglandin production do not appear to play a major role in the pathogenesis of enteropathy.

Aims: We examined changes in the expression of a pro-angiogenic factor, vascular endothelial growth factor (VEGF), and an anti-angiogenic factor, endostatin, as well as matrix metalloproteinase (MMP)-2 and MMP-9 in the rat small intestine after administration of indomethacin and investigated the roles of these factors in the healing of indomethacin-induced small intestinal ulcers., Main Methods: Male SD rats were given indomethacin (10mg/kg) p.o. and euthanized at various time points (3-24h and 2-7days) after the administration. To impair the healing of these lesions, low-dose of indomethacin (2mg/kg) was given p.o. once daily for 6days starting 1day after ulceration. Levels of VEGF, endostatin, MMP-2 and MMP-9 were determined by Western blotting., Key Findings: The expression of both VEGF and endostatin was upregulated after the ulceration. Repeated administration of low-dose indomethacin impaired the ulcer healing with a decrease of VEGF expression and a further increase of endostatin expression, resulting in a marked decrease in the ratio of VEGF/endostatin expression. The levels of MMP-2 and MMP-9 were both significantly increased after the ulceration, but these responses were suppressed by the repeated indomethacin treatment. The healing of these ulcers was significantly delayed by the repeated administration of MMP inhibitors such as ARP-101 and SB-3CT., Significance: The results confirm the importance of the balance between pro-angiogenic and anti-angiogenic activities in the healing of indomethacin-induced small intestinal damage and further suggest that the increased expression of MMP-2 and MMP-9 is another important factor for ulcer healing in the small intestine., (© 2013.)

Lactobacillus rhamnosus GG (LGG) and Bifidobacterium lactis Bb12 (Bb12) were assessed for their potential to prevent indomethacin-induced ulceration in the small intestine of Sprague-Dawley rats. Rats were gavaged skim milk, LGG, or Bb12 twice daily for 14 days. Between days 7-14, rats were gavaged indomethacin (Indo; 6 mg/kg). At sacrifice, small intestine was scored for ulceration and sampled for histologic, immunohistochemical, and myeloperoxidase (MPO) analyses. Indo+LGG-treated rats exhibited a 2.3-fold increase in MPO activity and a 9.8-fold increase in ulceration area compared to Indo-treated controls; these parameters did not differ significantly between Indo+Bb12 and Indo-treated controls. Crypt cell apoptosis decreased by 82% in Indo+Bb12-treated and 55% in Indo+LGG-treated rats compared to Indo-treated controls. Proliferation increased by 209% in Indo+LGG-treated animals compared to Indo-treated controls. Bb12 did not reduce indomethacin-induced intestinal ulceration, whereas LGG actually increased some indicators of injury. LGG and Bb12, at the doses tested, cannot alleviate indomethacin-induced intestinal injury.

Diabetes-prone BioBreeding (BBdp) rats often present an enteropathy that may precede the onset of autoimmune insulitis. The aim of the present study was to assess the influence of sex, the time course, the strain specificity, the distribution along the intestinal tract and the effect of diet for the changes in the activity of gut invertase, maltase and lactase found in BBdp rats, as compared with both Wistar-Furth (WF) and diabetes-resistant BioBreeding (BBc) rats. These hydrolases were measured, therefore, at day 10, 30, 45, 70, 95 and 120 in three intestinal segments of WF, BBc and BBdp rats fed, after weaning, either a protective hydrolysed casein diet, which decreases the incidence of diabetes in the BBdp rats, or one of two diabetogenic diets (National Toxicology Program; NTP or wheat-gluten-based; WG) [corrected]. Except for a somewhat lower lactase activity in the BBdp rats, no obvious difference in hydrolyase activity between the three strains of rats was observed at day 10. Between days 30 and 120, however, the activity of the hydrolases, especially that of invertase and lactase, was lower in the BBdp rats than in either the WF or BBc rats, at least when considering the animals fed either the NTP or WG diet. These findings support the view that BBdp rats exposed to a diabetogenic diet develop an enteropathy well before the onset of autoimmune insulitis, in a manner somehow comparable with the situation found in some type 1 diabetic patients, in whom coeliac disease may be diagnosed before diabetes onset.

Pelvic radiotherapy almost always induces intestinal symptoms. We investigated the radiation-induced damage to the small intestinal mucosa and evaluated its relationship with symptoms, using cellobiose/mannitol permeability test (CE/MA) and plasma postheparin diamine oxidase test (PHD) in 20 patients treated with pelvic radiotherapy. The symptoms developed during radiotherapy were noted. Intestinal permeability significantly (p=0.013) increased from 0.021 +/- 0.026 to 0.047 +/- 0.055 (mean +/- SD) after 15 days of radiotherapy, while it returned to normal values (0.010 0.015) at the end of radiotherapy. PHD values did not change. All patients developed intestinal symptoms. These findings indicate that pelvic radiotherapy induces an early small bowel mucosa damage followed by mucosal adaptation. Acute intestinal symptoms during pelvic radiotherapy may not depend only on small intestinal mucosal damage.

The fact that the enzymes splitting food nutrients, those of protein nature in particular, not only in the epithelial cells of the small bowel, but in the lower structures of the intestinal wall, i.e. in the stromal and muscle serous layers, is shown for the first time. They are integral parts of the intestinal enzymatic barrier that protects the internal medium of the body from penetration of proteins and peptides. The activities of the enzymes which are present in the epithelial, stromal, and muscle serous layers have been demonstrated to be substantially changed in disorders (immobilization in the presence of starvation, surgical interventions into the small bowel). It is suggested that examining the functions of the postepithelial enzymatic barrier along with those of the epithelial and immunological ones will provide a deeper insight into some certain disorders of the alimentary tract.

The authors studied duodenal myoelectric activity and the activity of trypsin, alpha 1-antitrypsin, alpha 2-macroglobulin, alpha-amylase, and kallikrein after 15-minute occlusion of the hepatic portal vein. The correlation was found between the activity of alpha 1-antitrypsin and the phases of the myoelectrical complex. It is concluded that the discharge of pancreatic proteases during an operative trauma may underlie the pathogenesis of postoperative inhibition of intestinal peristalsis.

The effect of chronic dietary antigen challenge on the intestine was examined in sensitized rats. Three groups of Hooded-Lister rats were studied: animals sensitized to egg albumin; sham-sensitized animals; and unmanipulated controls. In sensitized rats, serum immunoglobulin E titers to egg albumin were greater than or equal to 1:64, whereas control and pair-fed rats showed no response. Sensitized rats received egg albumin 1 mg/ml in drinking water and rat chow ad libitum. Pair-fed animals also received egg albumin but were pair-fed with sensitized animals. Controls received water and rat chow ad libitum. Chronic antigen challenge resulted in reduced food intake and weight gain in sensitized animals. When the rats were killed after 9 days of antigen exposure, proximal intestine from experimental animals showed decreased disaccharidase activity, brush-border microvillus surface, area, and villus height. Crypt depth and enterocyte migration rate were increased. Mucosal mast cell involvement was suggested by mast cell proliferation, evidence of mast cell degranulation, and increased serum rat mast cell protease II levels. At the time of death, only sensitized jejunum demonstrated an increase in short-circuit current in Ussing chambers in response to antigen challenge. The findings indicate that chronic antigen exposure leads to intestinal injury, reduced food intake, and diminished weight gain.

Intestinal mucosal damage and restitution were examined following antigen-induced systemic anaphylaxis in Nippostrongylus brasiliensis immunized rats. The rats were injected intravenously with N. brasiliensis antigen or saline. At 60 min, morphological and biochemical parameters were determined in jejunum and ileum, and the epithelial permeability was assessed by measuring recovery of 51Cr-ethylenediaminetetraacetic acid in the blood after injecting it into a ligated segment. Antigen challenge resulted in significant abnormalities: (1) villus damage with sloughing of enterocytes; (2) decreased activities of brush border enzymes; (3) decreased levels of mucosal histamine and rat mast cell protease II (mast cell mediators), and (4) increased uptake of 51Cr-ethylenediaminetetraacetic acid. Progression of the injury was examined by taking consecutive biopsies at 15-min intervals for 60 min and then at 5 h. At 15 min, an abnormality was present in all sections which ranged from minor oedema and enterocyte detachment at villus tips to virtual complete destruction of the apical region. Restitution occurred by villus contraction with migration of the epithelium over the damaged regions. At 5 h, the epithelium had resealed, but the villi were significantly reduced in height.

To investigate further the pathophysiology of rotavirus-induced diarrhea, changes in specific activities of eight relevant intestinal enzymes [alkaline phosphatase, thymidine kinase, lactase, maltase, sucrase, Na+,K+-adenosine triphosphatase (ATPase), adenylate and guanylate cyclases] were measured following infection of suckling mice with murine rotavirus (epizootic diarrhea of infant mouse strain) and compared with age-matched control mice. The concentration of lactose within the lumen of the gastrointestinal tract during infection was also measured. During the course of infection, activities of alkaline phosphatase and lactase decreased, whilst the activity of thymidine kinase increased. Precocious maturation profiles of sucrase and maltase enzymes were observed. No significant changes were detected in the activities of Na+,K+-ATPase or the adenylate and guanylate cyclases. These results are discussed in relation to existing and novel hypotheses on the pathogenesis of rotavirus-induced diarrhea.

In comparison to normal controls (n = 71) the activity of intestinal alkaline phosphatase in feces is reduced in chronic bowel disease using an immunoprecipitation method: patients with Crohns disease (n = 40) or inactive ulcerative colitis (n = 29) demonstrate small changes of fecal intestinal alkaline phosphate activity in comparison to normal controls. Intestinal alkaline phosphatase is reduced in patients with active ulcerative colitis (n = 11) to 50%, in patients with uraemic enteropathy (n = 18) to 30% and in patients with coeliac disease (n = 14) to 20% of the activity observed in normal controls. During cytostatic treatment of malignant tumors, fecal intestinal alkaline phosphatase activity increases as a sign of toxic damage of the intestinal mucosa.

In 63 infants and children with a histological normal mucosa of the duodenum, without an isolated defect of enzyme and with a normal increase of xylose and glucose in serum after a combined xylose-lactose loading test the activities of disaccharidases were log normal distributed. The asymmetric distributions were transformed into symmetric ones and the geometric mean (x) as well as the range (+/- 2 s) of maltase, saccharase, isomaltase, lactase and trehalase were calculated. Only the activity of lactase shows a significant dependency on age. In the first year of age the lower limit (x -- 2 s) of this enzyme is much higher than later.

Activities of lactase, sucrase, and maltase were determined in small intestinal biopsies of 125 children with coeliac disease, cow's milk protein intolerance, transient gluten intolerance, nonspecific enteropathies, and controls. Four cases of primary disaccharidase deficiencies could be identified. In the enteropathies, morphometric data were more closely correlated to the degree of the mucosal lesion (r = -0.92 for crypt depth) than were disaccharidase activities (r = 0.61 for lactase). In a stepwise discriminant analysis of the patient groups, based upon immunological, morphometric, and biochemical variables, lactase activity was a valuable secondary criterion, ranking third among the variables used.

We report what we believe to be the first proven marked concomittant elevations in serum creatine kinase (CK) and lactic dehydrogenase (LD) in a patient with bowel necrosis. The necrosis was the result of infarction secondary to bowel strangulation. The serum from this patient showed elevation of total CK activity resulting from an abnormal amount of MM, MB, and BB isoenzymes with LD2, LD3, and LD5 yielding 18 per cent, 19 per cent, and 29 per cent, respectively, of the total LD activity.

The interrelationship of enterokinase and trypsin activities were investigated in 133 infants and children with a variety of gastrointestinal and pancreatic disorders. Fourteen patients with diarrhea and grade II mucosal injury revealed a significant (P less than 0.01) reduction of enterokinase, trypsin, and disaccharidase activites as compared to 59 children with normal mucosa. Nine patients with cystic fibrosis and pancreatic insufficiency had normal mucosal enterokinase activity and elevated intraluminal enterokinase activity with very low or no trypsin activity. Patients with hypoproteinemia and gastrointestinal protein loss, associated with intestinal lymphangiectasia (4 patients) and intestinal lymphoid nodular hyperplasia (3 patients), had normal or insignificant decrease of enterokinase and trypsin activities. In patients with steatorrhea, a normal sweat test, normal intestinal mucosa, and absent trypsin activity, two entities were defined. One group (3 patients) was diagnosed as Schwachman-Diamond syndrome with pancreatic insufficiency and normal mucosal and intraluminal enterokinase activity. The second group (2 patients) with absent mucosal and intraluminal enterokinase activity and normal lipase and amylase activities was diagnosed as congenital enterokinase deficiency.

Few studies have been published on peptide hydrolase activities of human small intestine mucosa. We developed methods to screen tissue extracts for such enzymes and to quantitate hydrolase activities for dipeptides containing the aromatic amino acid L-phenylalanine. The screening procedure indicated glycyl-L-proline hydrolase activity was reduced in biopsy specimens from patients with flattened intestinal mucosa. To explore this further, we established optimal assay conditions for hydrolase activities (a) glycyl-L-proline, (b) L-phenylalanyl-L-proline, (c) L-alanyl-L-phenylalanine, and (d) L-phenylalanylglycine. Biopsy specimens from patients with various intestinal disorders, but without flattened mucosa, and from three patients with flattened mucosa, showed a disproportionate reduction in activities (a) and (b), with the reduction being significantly more marked in the latter patients. We suggest that intestinal imidopeptide hydrolase activities, such as (a) and (b), are sensitive to changes in intestinal disease generally, particularly to the altered physiology associated with flattening of the mucosa, and are secondary to, rather than a cause of, the intestinal pathology. Our finding that intestinal alkaline phosphatase activity tended to parallel imidopeptide hydrolase activity, and that activity (a) was partially localized to the particulate fraction of mucosal homogenate, suggested that imidopeptide hydrolase activities may be located in the microvilli of the intestinal epithelium and that, like alkaline phosphatase activity, they may be reduced in flattened mucosae, in part at least because of the pathologic changes in the microvilli. In our studies of control subjects we did not detect peptide hydrolase activity deficiency analogous to asymptomatic disaccharidase deficiency.