Molecular Mechanism of Stimulation of Na-K-ATPase by Leukotriene D4 in Intestinal Epithelial Cells

Na-K-ATPase provides a favorable transcellular Na gradient required for the functioning of Na-dependent nutrient transporters in intestinal epithelial cells. The primary metabolite for enterocytes is glutamine, which is absorbed via Na-glutamine co-transporter (SN2; SLC38A5) in intestinal crypt cells. SN2 activity is stimulated during chronic intestinal inflammation, at least in part, secondarily to the stimulation of Na-K-ATPase activity. Leukotriene D4 (LTD4) is known to be elevated in the mucosa during chronic enteritis, but the way in which it may regulate Na-K-ATPase is not known. In an in vitro model of rat intestinal epithelial cells (IEC-18), Na-K-ATPase activity was significantly stimulated by LTD4. As LTD4 mediates its action via Ca-dependent protein kinase C (PKC), Ca levels were measured and were found to be increased. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, also mediated stimulation of Na-K-ATPase like LTD4, while BAPTA-AM (Ca chelator) and calphostin-C (Cal-C; PKC inhibitor) prevented the stimulation of Na-K-ATPase activity. LTD4 caused a significant increase in mRNA and plasma membrane protein expression of Na-K-ATPase α1 and β1 subunits, which was prevented by calphostin-C. These data demonstrate that LTD4 stimulates Na-K-ATPase in intestinal crypt cells secondarily to the transcriptional increase of Na-K-ATPase α1 and β1 subunits, mediated via the Ca-activated PKC pathway.

Comparison of the expression, activity, and fecal concentration of intestinal alkaline phosphatase between healthy dogs and dogs with chronic enteropathy

OBJECTIVE To compare expression, activity, and fecal concentration of intestinal alkaline phosphatase (IAP) between healthy dogs and dogs with chronic enteropathy (CE). ANIMALS 9 healthy university-owned Beagles and 109 healthy client-owned dogs (controls) and 28 dogs with CE (cases). PROCEDURES Cases were defined as dogs with persistent (> 3 weeks) gastrointestinal signs that failed to respond to antimicrobials and anti-inflammatory doses of prednisolone or dietary trials, did not have mechanical gastrointestinal abnormalities as determined by abdominal radiography and ultrasonography, and had a diagnosis of lymphoplasmacytic enteritis or eosinophilic gastroenteritis on histologic examination of biopsy specimens. Duodenal and colonic mucosa biopsy specimens were obtained from the 9 university-owned Beagles and all cases for histologic examination and determination of IAP expression (by real-time quantitative PCR assay) and activity (by enzyme histochemical analysis). Fecal samples were obtained from all dogs for determination of fecal IAP concentration by a quantitative enzyme reaction assay. RESULTS For dogs evaluated, IAP expression and activity were localized at the luminal side of epithelial cells in the mucosa and intestinal crypts, although both were greater in the duodenum than in the colon. Active IAP was detected in the feces of all dogs. Intestinal alkaline phosphatase expression and activity were lower for cases than for controls, and fecal IAP concentration for dogs with moderate and severe CE was lower than that for dogs with mild CE. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with CE had impaired IAP expression and activity. Additional research is necessary to elucidate the role of IAP in the pathogenesis of CE.

A case of pediatric patient with acute enteritis due to CTX-M-1 5 extended-spectrum β-lactamase-producing Salmonella Blockley

This clinical case report concerns a pediatric patient with acute enteritis caused by multi-drug resistant Salmonella enterica serovar Blockley (Salmonella Blockley). A 3-year-old boy presented to our emergency room with a 5-day history of fever, abdominal pain, and bloody diarrhea. Stool culture tested positive for a Salmonella species, while the blood culture was negative. The patient was successfully treated with an oral antibiotic regimen of fosfomycin. The stool isolate was found to be resistant to multiple drugs, including cefpodoxime, cefotaxime, ceftazidime, and aztreonam, and was confirmed to be a CTX-M-15 extended-spectrum β-lactamase (ESBL)-producing strain of Salmonella Blockley. This is the first report of a pediatric patient in Japan with acute enteritis caused by a CTX-M-15 ESBL- producing strain of Salmonella Blockley.

Nod2-Rip2 Signaling Contributes to Intestinal Injury Induced by Muramyl Dipeptide Via Oligopeptide Transporter in Rats

BACKGROUND AND AIMS

PepT1 can transport bacterial oligopeptide products and induce intestinal inflammation. Our aim was to investigate the mechanism of the small intestine injury induced by bacterial oligopeptide product muramyl dipeptide (MDP) which is transported by PepT1.

METHODS

We perfused the jejunum with a solution with or without MDP, or with a solution of MDP + Gly-Gly and explored the degree of inflammation to determine the role of PepT1-Nod2 signaling pathway in small intestine mucosa.

RESULTS

MDP perfusion induced inflammatory cell accumulation and intestinal damage, accompanied by an increase in mucosal Nod2 and Rip2 transcript expression. NFκB activity and inflammatory cytokine expression, including serum levels of TNF-α, IL-1β, and IL-6, increased in the MDP group compared to the controls; these effects were reversed by perfusion of the nutritional dipeptide Gly-Gly.

CONCLUSION

MDP can be transported through PepT1, causing inflammatory damage in the rat small intestine. Nod2-Rip2-NFκB signaling involved in the small intestinal inflammatory injury caused by MDP which is transported through PepT1.

Local corticosterone production and angiotensin-I converting enzyme shedding in a mouse model of intestinal inflammation

AIM: To investigate local corticosterone production and angiotensin-I converting enzyme (ACE) protein expression and their interaction in healthy and inflamed intestine.

METHODS: Acute intestinal inflammation was induced to six weeks old male Balb/c mice by administration of either 3% or 5% dextran sodium sulfate (DSS) in drinking water for 7 d (n = 12 in each group). Healthy controls (n = 12) were given tap water. Corticosterone production and ACE protein shedding were measured from ex vivo incubates of the small and large intestine using EIA and ELISA, respectively. Morphological changes of the intestinal wall were assessed in hematoxylin-eosin stained tissue preparations of jejunum and distal colon. Effects of angiotensin II, captopril and metyrapone on corticosterone production was assessed by incubating pieces of small intestine of healthy mice in the presence of 0.1, 1 or 10 μmol/L angiotensin II, 1, 10 or 100 μmol/L captopril or 1, 10 or 100 μmol/L metyrapone solutions and measuring corticosterone released to the incubation buffer after 90 min (n = 5 in each group).

RESULTS: Both concentrations of DSS induced inflammation and morphological changes in large intestines but not in small intestines. Changes were observed as distortions of the crypt structure, mucosal erosion, immune cell infiltration to the mucosa and submucosal edema. Ex vivo corticosterone production (2.9 ± 1.0 ng/mL vs 2.0 ± 0.8 ng/mL, P = 0.034) and ACE shedding (269.2 ± 97.1 ng/mL vs 175.7 ± 52.2 ng/mL, P = 0.016) were increased in small intestines in 3% DSS group compared to the controls. In large intestine, corticosterone production was increased compared to the controls in both 3% DSS (229 ± 81 pg/mL vs 158 ± 30 pg/mL, P = 0.017) and 5% DSS groups (366 ± 163 pg/mL vs 158 ± 30 pg/mL, P = 0.002). Large intestine ACE shedding was increased in 5% DSS group (41.5 ± 9.0 ng/mL vs 20.9 ± 5.2 ng/mL, P = 0.034). Angiotensin II treatment augmented corticosterone production in small intestine at concentration of 10 μmol/L (0.97 ± 0.21 ng/mg protein vs 0.40 ± 0.09 ng/mg protein, P = 0.036).

CONCLUSION: Intestinal ACE shedding is increased by DSS-induced intestinal inflammation and parallels local corticosterone production. ACE product angiotensin II stimulates corticosterone formation in healthy intestine.

Effects of rifaximin on indomethacin-induced intestinal damage in guinea-pigs

AIM

Enterobacterial translocation into the gut mucosa is the first step required for activation of neutrophils and inducible nitric oxide synthase (iNOS), involved in the pathogenesis of indomethacin-induced intestinal lesions. Rifaximin may limit NSAID-associated intestinal damage by decreasing the bacterial load. We aimed to study the effect of rifaximin on indomethacin-induced intestinal damage in guinea-pigs.

MATERIALS AND METHODS

Twenty-four guinea pigs, equally divided in four interventional groups (A-D), received indomethacin, given orally once daily (30 mg/kg) for three consecutive days. In groups B, C, D different doses of rifaximin (50 mg/kg, 100 mg/kg and 200 mg/kg) were given orally two hours before indometachin administration. Semi-quantitative grades were measure for gross findings, degenerative lesions, neutrophils and eosinophils infiltrates and iNOS immunopositivity. Statistical comparisons used Mann Whitney Test, with a Bonferroni correction for alpha (p ≤ 0.016).

RESULTS

Statistical analysis of graded gross findings, microscopic degenerative lesions, endothelium damage and iNOS immunopositivity found no difference between A and B groups. Significant fewer gross findings (U = 3, p = 0.015), microscopic degenerative lesions (U = 2, p = 0.008) and lower grades for iNOS immunopositivity (U = 0, p = 0.002) were found in group C compared with group A. In group D, significant lower grades for iNOS immunopositivity were obtained (U = 0, p = 0.002) compared with group A and fewer degenerative lesions without reaching statistical significance (U = 4, p = 0.026).

CONCLUSIONS

100 mg/kg of rifaximin proved efficient in preventing gut degenerative lesions induced by indomethacin in a guinea pig model, the iNOS activity being significantly decreased.

Curcumin protects intestinal mucosal barrier function of rat enteritis via activation of MKP-1 and attenuation of p38 and NF-κB activation

Background

Intestinal mucosa barrier (IMB) dysfunction results in many notorious diseases for which there are currently few effective treatments. We studied curcumin's protective effect on IMB and examined its mechanism by using methotrexate (MTX) induced rat enteritis model and lipopolysaccharide (LPS) treated cell death model.

Methodology/Principal Findings

Curcumin was intragastrically administrated from the first day, models were made for 7 days. Cells were treated with curcumin for 30 min before exposure to LPS. Rat intestinal mucosa was collected for evaluation of pathological changes. We detected the activities of D-lactate and diamine oxidase (DAO) according to previous research and measured the levels of myeloperoxidase (MPO) and superoxide dismutase (SOD) by colorimetric method. Intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were determined by RT-PCR and IL-10 production was determined by ELISA. We found Curcumin decreased the levels of D-lactate, DAO, MPO, ICAM-1, IL-1β and TNF-α, but increased the levels of IL-10 and SOD in rat models. We further confirmed mitogen-activated protein kinase phosphatase-1 (MKP-1) was activated but phospho-p38 was inhibited by curcumin by western blot assay. Finally, NF-κB translocation was monitored by immunofluorescent staining. We showed that curcumin repressed I-κB and interfered with the translocation of NF-κB into nucleus.

Conclusions/Significance

The effect of curcumin is mediated by the MKP-1-dependent inactivation of p38 and inhibition of NF-κB-mediated transcription. Curcumin, with anti-inflammatory and anti-oxidant activities may be used as an effective reagent for protecting intestinal mucosa barrier and other related intestinal diseases.

A novel model of ischemic enteritis induced in rats by stenosis of the superior mesenteric artery

AIMS

We established a new model of ischemic enteritis in rats and evaluated its usefulness for screening prophylactic drugs.

MAIN METHODS

Male SD rats were used after 18 h of fasting. Under ether anesthesia, the superior mesenteric artery (SMA) was exposed, and a calibrated stenosis was produced by placing a needle on a blood vessel, ligating both the vessel and needle, and then removing the needle from the ligature.

KEY FINDINGS

The stenosis caused severe damage on the anti-mesenteric side of the small intestine within 3 days; the severity of the damage increased with the gauge of a needle. No damage occurred in the small intestine following the stenosis with a needle of less than 21 gauge. Multiple hemorrhagic lesions occurred at an incidence of 100% when a 23-gauge needle was used. The development of enteritis was accompanied by enterobacterial invasion in the mucosa, with an up- regulation of inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production. The ischemia-induced enteritis was significantly prevented by repeated treatment with aminoguanidine (a selective iNOS inhibitor), L-NAME (a nonselective NOS inhibitor), ampicillin, and aztreonam (a gram- negative bacterium antibiotic), but not vancomycin (a gram-positive bacterium antibiotic).

SIGNIFICANCE

These results showed that a novel model of ischemic enteritis is induced in rats by stenosis of the SMA, this model may be useful for screening drugs against ischemic enteritis, and gram-negative bacteria as well as iNOS/NO are involved in the pathogenesis of enteritis in this model.

5-aminosalicylic acid improves indomethacin-induced enteropathy by inhibiting iNOS transcription in rats

Nitric oxide has been implicated in the pathogenic mechanism of inflammatory bowel disease states. We evaluated indomethacin-induced enteropathy in rats, in relation to the expression of the inducible isoform of NO synthase (iNOS) using aminosalicylic acid (5-ASA), its isomer 4-ASA (10 or 50 mg/kg/day, po), and dexamethasone, an iNOS transcription inhibitor (3 mg/kg/day, sc). Enteropathy was induced by indomethacin (7.5 mg/kg/day, sc) for two days and the small intestine was examined for lesions over the next 14 days. Indomethacin-induced small-intestinal ulcer size, mucosal myeloperoxidase activity, iNOS expression and serum nitrite/nitrate levels were maximally increased by day 4 and gradually decreased by day 14. Treatment with 5-ASA, but not 4-ASA, decreased indomethacin-induced ulcer length, myeloperoxidase activity, serum nitrite/nitrate levels and iNOS expression at day 4. Dexamethasone had a greater effect than 5-ASA in reducing myeloperoxidase activity and ulcer length by 26 and 32%, respectively. Dexamethasone also reduced serum nitrate/nitrite and iNOS expression to their basal levels. In conclusion, inhibition of iNOS expression by 5-ASA appears to be associated with diminished intestinal ulceration in indomethacin-induced enteropathy.

Blockade of tumor necrosis factor-alpha-converting enzyme improves experimental small intestinal damage by decreasing matrix metalloproteinase-3 production in rats

OBJECTIVE

Tumor necrosis factor (TNF)-alpha-converting enzyme (TACE), which has been purified, regulates maturity of TNF-alpha. Matrix metalloproteinases (MMPs) play a key role in various inflammatory conditions. The incidence of intestinal damage has increased, but the mechanism and treatment have not been well understood. The purpose of this study was to investigate the roles of TACE and MMP in indomethacin (Indo)-induced intestinal damage as well as the therapeutic effects of TACE inhibitor and selective MMP inhibitor (sMMPi) on this intestinal damage in rats.

MATERIAL AND METHODS

In the first experiment, serial changes in intestinal ulcers and the production of MMP were investigated. In the second experiment, we assessed the effect of three TACE and/or MMP inhibitors and the production of TNF-alpha, TACE, MMP-3, -9 and tissue inhibitor of MMP (TIMP)-1. The rats were divided into five groups: a control group, and four groups that received Indo alone, Indo plus TACE inhibitor (GM6001), Indo plus a selective MMP-3 inhibitor and Indo plus an MMP-9/13 inhibitor, respectively.

RESULTS

MMP-3 was overexpressed at 24 h after Indo administration, when intestinal injury was most prominent macroscopically and microscopically. GM6001 significantly decreased ulcer severity and suppressed MMP-3 in a dose-dependent fashion. The selective MMP-3 inhibitor dose-dependently ameliorated intestinal damage to the same degree as GM6001, but the MMP-9 inhibitor had no effect on the injury.

CONCLUSIONS

MMP-3 inhibition ameliorates intestinal damage without apparently affecting either TNF-alpha or TACE production and the dose-response curve suggests that the beneficial effect of the so-called TACE inhibitor is actually mainly mediated via MMP-3 inhibition rather than TNF-alpha inhibition.

Mitogen-activated protein kinase and activator protein-1 dependent signals are essential for Bacteroides fragilis enterotoxin-induced enteritis

The approximately 20-kDa heat-labile toxin produced by enterotoxigenic Bacteroides fragilis is known to be associated with the development of enteritis. However, the molecular mechanism involved is not yet fully understood. In this study, we assessed whether B. fragilis enterotoxin (BFT)-induced enteritis is related to mitogen-activated protein kinase (MAPK) signaling pathways. In human colon epithelial cells, BFT activated three major MAPK cascades. The activation of p38 was sustained for a relatively long period, while the stimulation of extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) was transient. BFT stimulation also activated AP-1 signals composed of c-Jun/c-Fos heterodimers. The p38 inhibitor SB203580 and the ERK inhibitor U0126 reduced not only AP-1 activity, but also decreased IL-8 and MCP-1 expression. In addition, the overexpression of superrepressors for c-Jun and Ras induced by BFT stimulation decreased the levels of IL-8 and MCP-1 production. Furthermore, SB203580 prevented BFT-induced colitis in the mouse ileum, as evidenced by significant decreases in villous destruction, neutrophil infiltration, and mucosal congestion. These results suggest that a pathway, including Ras, MAPK, and subsequent AP-1 activation, is required for IL-8 and MCP-1 expression in intestinal epithelial cells exposed to BFT, and can be involved in the development of enteritis.

Effect of chronic cold stress on intestinal epithelial cell proliferation and inflammation in rats

The present study evaluated the effect of chronic cold stress on intestinal epithelial cell proliferation and inflammation. Male Wistar rats were subjected to cold exposure for three weeks. At the end of the cold exposure, intestinal cell proliferation, luminal nitrite and protein levels, intestinal myeloperoxidase activity and mast cell numbers were evaluated. Severely compromised proliferation rate of the crypt-base cells was observed under chronic stress conditions. Cells isolated from stressed rats showed a decreased DNA content in villus and lower villus cell fractions and an increased DNA content in the crypt cells, as compared to controls. Chronic cold stress resulted in increased luminal nitrite, luminal protein levels, and intestinal myeloperoxidase activity. The number of mast cells was significantly elevated under chronic stress conditions. Chronic cold stress resulted in a compromised intestinal epithelial cell proliferation rate and induced inflammation in the rat small intestine, through the combined action of nitric oxide, neutrophils and mast cells.

Inhibition of Rho kinase modulates radiation induced fibrogenic phenotype in intestinal smooth muscle cells through alteration of the cytoskeleton and connective tissue growth factor expression

BACKGROUND

Late radiation enteritis in humans is associated with accumulation of extracellular matrix and increased connective tissue growth factor (CTGF) expression that may involve intestinal muscular layers.

AIMS

We investigated the molecular pathways involved in maintenance of radiation induced fibrosis by gene profiling and postulated that alteration of the Rho pathway could be associated with radiation induced fibrogenic signals and CTGF sustained expression.

PATIENTS AND METHODS

Ileal biopsies from individuals with and without radiation enteritis were analysed by cDNA array, and primary cultures of intestinal smooth muscle cells were established. Then, the effect of pharmacological inhibition of p160 Rho kinase, using Y-27632, was studied by real time reverse transcription-polymerase chain reaction, western blot, and electrophoretic mobility shift assay.

RESULTS

Molecular profile analysis of late radiation enteritis showed alterations in expression of genes coding for the Rho proteins. To investigate further the involvement of the Rho pathway in intestinal radiation induced fibrosis, primary intestinal smooth muscle cells were isolated from radiation enteritis. They retained their fibrogenic differentiation in vitro, exhibited a typical cytoskeletal network, a high constitutive CTGF level, increased collagen secretory capacity, and altered expression of genes coding for the Rho family. Rho kinase blockade induced a simultaneous decrease in the number of actin stress fibres, alpha smooth muscle actin, and heat shock protein 27 levels. It also decreased CTGF levels, probably through nuclear factor kappaB inhibition, and caused decreased expression of the type I collagen gene.

CONCLUSION

This study is the first showing involvement of the Rho/Rho kinase pathway in radiation fibrosis and intestinal smooth muscle cell fibrogenic differentiation. It suggests that specific inhibition of Rho kinase may be a promising approach for the development of antifibrotic therapies.

Glutamine decreases lipopolysaccharide-induced intestinal inflammation in infant rats

Using a gastrostomy-fed (GF) rat infant "pup-in-a-cup" model, the effects of protein deprivation and supplemental glutamine (Gln) and glutamate (Glu) were examined to test the hypothesis that Gln decreases the proinflammatory response induced by LPS in the developing infant rat small intestine. Four groups of 6- to 7-day-old pups were fed a rat milk substitute (RMS), one providing 100% and three providing 25% of normal protein intake for another 6 days. Two of the 25% protein-fed groups received supplemental Gln or Glu. GF and LPS treatment blunted body growth and intestinal villus height and increased intestinal cytokine-induced neutrophil chemoattractant (CINC) mRNA in the protein-deprived, non-Gln-treated group compared with mother-fed pups (P < 0.05). Gln blunted intestinal CINC mRNA (P < 0.05), but Glu did not. Intestinal CINC peptide in the LPS-treated pups provided 100 and 25% protein was elevated approximately 13-fold compared with the mother-reared pups (P < 0.001). Gln and Glu decreased intestinal CINC peptide by 73 and 80%, respectively. GF, LPS-treated pups also had a higher level of plasma CINC peptide (P < 0.05). Gln but not Glu decreased plasma CINC peptide (P < 0.05). An approximate sixfold elevation of intestinal MPO activity in the GF, LPS-treated rats was decreased by Gln and Glu by 92% (P < 0.001) and 54% (P < 0.05), respectively. Intestinal and plasma TNF-alpha were increased in GF, LPS-treated pups (P < 0.01), and Gln and Glu both blunted this increase (P < 0.05) in the intestine but not in the plasma. The results indicate that Gln decreases the LPS-induced inflammatory response in infant rat intestine under different conditions of protein intake.

A retrospective analysis of hepatic injury in horses with proximal enteritis (1984-2002)

The purpose of this study was to test the hypothesis that horses with proximal enteritis (PE) are predisposed to hepatic injury. We also determined whether the presence of liver injury in horses with PE was associated with other clinicopathologic abnormalities or affected outcome. The medical records of all horses admitted for evaluation of colic and gastric reflux between 1984 and 2002 were reviewed. Horses were considered to have PE if the diagnosis was made at surgery or postmortem examination or if they had clinical findings consistent with PE. Horses with a small intestinal strangulating obstruction (SISO) were used as the control group. Historic and clinicopathologic data were collected for each horse. The data were analyzed by descriptive statistics, parametric and nonparametric analyses, and logistic regression. Horses with PE had significantly higher serum gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) activities than horses with SISO (P < .05). Horses with PE were 12.1 times more likely to have high GGT activities than were horses with SISO. Horses with PE had an increased risk of at least 1 hepatic enzyme being increased if a high anion gap or large volume of reflux was present. Our conclusion is that horses with PE are more likely to have hepatic injury than horses with SISO. The mechanism of hepatic injury may involve ascending infection from the common bile duct, absorption of endotoxin or inflammatory mediators from the portal circulation, or hepatic hypoxia resulting from systemic inflammation and endotoxemic shock.

[Digestive pathology and digestive function of small intestine mucous layer]

The research of small intestine mucous layer at children and adults is carried out. It is revealed high meanings enzyme distribution in human small intestine mucous layer and their change at celiac disease, food allergy, short-bowel syndrome.

Total parenteral nutrition adversely affects gut barrier function in neonatal piglets

Sepsis is the most common morbidity in preterm infants, who often receive total parenteral nutrition (TPN). We hypothesized that gut barrier function is compromised in TPN-fed compared with enterally fed newborn piglets (ENT pigs). Colostrum-deprived newborn pigs were implanted with jugular venous and bladder catheters under general anesthesia. Pigs were either administered TPN (n = 15) or fed formula (ENT pigs, n = 15). After 6 days, pigs were gavaged a solution of mannitol, lactulose, and polyethylene glycol 4000 (PEG 4000) and urine was collected for 24 h. At 7 days, small bowel samples were assayed for myeloperoxidase activity, morphometry, and tight junction protein abundance. Intestinal contents and peripheral organ sites were cultured for bacteria. Urinary recovery (%dose) of mannitol (53 vs. 68) was lower, whereas that of lactulose (2.93 vs. 0.18) and PEG 4000 (12.78 vs. 0.96) were higher in TPN vs. ENT pigs, respectively (P < 0.05). Incidence of translocation was similar in TPN and ENT pigs. Myeloperoxidase activity was increased in TPN vs. ENT pigs in the jejunum (P < 0.001) and was weakly correlated with lactulose (R2 = 0.32) and PEG 4000 (R2 = 0.38) recovery. Goblet cell counts did not change, but intraepithelial lymphocyte numbers decreased with TPN. Only claudin-1 protein abundance was increased in the TPN group. We conclude that TPN is associated with impairment of neonatal gut barrier function as measured by permeability but not translocation.

Impaired activation of cytosolic phospolipase A(2) in inflamed canine colonic circular muscle

BACKGROUND & AIMS

Arachidonic acid (AA) is a critical second messenger in several cell types. We examined whether cholinergic AA acts as a second messenger in contraction of colonic circular muscle cells and if this role is altered by inflammation.

METHODS

The experiments were performed on single dispersed cells. AA release was measured by high-performance liquid chromatography. Escherichia coli membranes labeled with (3)H-AA were used as a substrate for determining phospholipase A(2) (PLA(2)) activity, and Western immunoblotting for protein expression.

RESULTS

Acetylcholine and the PLA(2) activator melittin induced cell contractions and AA release. Both effects were inhibited by the PLA(2) inhibitor ONO-RS-082. Cytosolic and membrane PLA(2) activities increased in response to acetylcholine. These were blocked by ONO-RS-082 and cytosolic PLA(2) 100-kilodalton antibody, but not by dithiothreitol, a secretory PLA(2) inhibitor. Acetylcholine- and melittin-stimulated release of AA and their contractile response were attenuated in inflamed cells. Immunoblotting indicated that the protein expression of cPLA(2) was suppressed during inflammation.

CONCLUSIONS

AA acts as a second messenger in muscarinic receptor-activated contractions of colonic circular muscle cells. cPLA(2) is the primary enzyme that releases AA in these cells; its expression as well as activation are significantly attenuated by inflammation. The attenuated release of AA may partly account for the inhibition of colonic circular muscle tone and phasic contractions observed during inflammation.

p38 MAP kinase activation by Clostridium difficile toxin A mediates monocyte necrosis, IL-8 production, and enteritis

Clostridium difficile toxin A causes acute neutrophil infiltration and intestinal mucosal injury. In cultured cells, toxin A inactivates Rho proteins by monoglucosylation. In monocytes, toxin A induces IL-8 production and necrosis by unknown mechanisms. We investigated the role of mitogen-activated protein (MAP) kinases in these events. In THP-1 monocytic cells, toxin A activated the 3 main MAP kinase cascades within 1 to 2 minutes. Activation of p38 was sustained, whereas stimulation of extracellular signal-regulated kinases and c-Jun NH(2)-terminal kinase was transient. Rho glucosylation became evident after 15 minutes. IL-8 gene expression was reduced by 70% by the MEK inhibitor PD98059 and abrogated by the p38 inhibitor SB203580 or by overexpression of dominant-negative mutants of the p38-activating kinases MKK3 and MKK6. SB203580 also blocked monocyte necrosis and IL-1beta release caused by toxin A but not by other toxins. Finally, in mouse ileum, SB203580 prevented toxin A-induced neutrophil recruitment by 92% and villous destruction by 90%. Thus, in monocytes exposed to toxin A, MAP kinase activation appears to precede Rho glucosylation and is required for IL-8 transcription and cell necrosis. p38 MAP kinase also mediates intestinal inflammation and mucosal damage induced by toxin A.

Site-specific lesion formation, inflammation and inducible nitric oxide synthase expression by indomethacin in the rat intestine

The involvement of nitric oxide (NO) formed by the inducible isoform of NO synthase (iNOS) has been investigated in the development of rat intestinal lesions following indomethacin administration. Over a 72-h period, indomethacin (10 mg kg(-1), s.c.) provoked a time-dependent increase in expression of iNOS (assessed by the conversion of radiolabelled L-arginine to citrulline) and enhancement of vascular leakage of radiolabelled human serum albumin in the jejunum which commenced 18 h after indomethacin. Similar effects were not observed in the ileum, colon or caecum. In addition, macroscopic lesions were detectable and myeloperoxidase activity (an index of neutrophil recruitment) were increased in the rat jejunum 18-24 h after indomethacin, but remained at basal levels in the ileum and colon. These findings suggest that indomethacin provokes a site-selective expression of iNOS in the rat jejunum which correlates with lesion formation and vascular leakage, whereas both the ileum and colon are spared.

Suppression of food intake is linked to enteric inflammation in nematode-infected rats

Our aim was to investigate the cause-effect relationship between intestinal inflammation induced by infection with enteric stages of Trichinella spiralis and decreased host food intake. A suppression of food intake in T. spiralis-infected rats occurred within the first 24 h postinfection (PI) and was maximized by day 6 PI. Food intake, cumulated over an 8-day PI period, decreased by 59% compared with uninfected animals. The anti-inflammatory glucocorticoid betamethasone 21-phosphate was orally administered to rats in their drinking water to suppress T. spiralis-induced jejunal inflammation. When treated with a low dose of glucocorticoid (5.2 microg/ml), food intake in infected rats was still significantly reduced, but only by 21% compared with glucocorticoid-treated, uninfected rats. At the highest glucocorticoid dose (10.4 microg/ml) administered, infection-induced reduction in food intake was not different from that of glucocorticoid-treated, uninfected counterparts. The elevation in jejunal myeloperoxidase activity caused by infection was also significantly blunted by oral glucocorticoid treatment. Our results suggest that suppressed host food intake during enteric T. spiralis infection is directly linked to intestinal inflammation.

Exposure to ionizing radiation increases responsiveness to neural secretory stimuli in the ferret jejunum in vitro

Experiments were designed to determine the effects of ionizing radiation on jejunal epithelial function in the ferret in vitro. Basal and stimulated electrolyte transport were determined in Ussing chambers at 0.5, 2, 24 and 48 h post-irradiation. Tissue histamine and 5-hydroxytryptamine levels were measured. Myeloperoxidase activity was also measured as an index of inflammation. Basal short circuit current was reduced at 2 h post-irradiation, but was elevated at 48 h. Basal conductance was significantly increased by 24 and 48 h. Responsiveness to electrical field stimulation was depressed at 0.5 h, and was greater than control by 24 and 48 h post-irradiation. Similarly, short circuit current responses to prostaglandin E2 were depressed at 0.5 h and elevated at 24 h. No significant change was observed in the response to carbachol post-irradiation, indicating that alterations in responsiveness were not likely at the level of the enterocyte. Changes in responsiveness to electrical field stimulation correlated significantly with increases in mucosal mast cell numbers. Myeloperoxidase activity, indicative of neutrophil infiltration, did not increase post-irradiation, nor was there histological evidence of an inflammatory cell infiltrate. There were no changes in tissue histamine or 5-hydroxytryptamine. Histology also revealed little microscopic morphological change from shams in tissue from irradiated ferrets. The results of this study demonstrate effects of irradiation on electrolyte transport in the ferret jejunum. The enhanced neurally evoked electrolyte transport observed at 24-48 h post-irradiation was not correlated with the development of inflammation, but was correlated with changes in mast cell numbers.

Phospholipase A2 stimulation of rat intestinal epithelial cell (IEC-6) migration

The effect of phospholipase A2 (PLA2) on intestinal epithelial cell migration was investigated using an in vitro wounding model of confluent monolayers of IEC-6. PLA2 (0.001-2 U/ml) enhanced IEC-6 cell migration in a dose dependent manner. Addition of 4-bromophenacyl bromide (BPB) (a PLA2 inhibitor) to PLA2 completely blocked the migration-promoting effect. However, addition of piroxicam (a cyclooxygenase inhibitor) or nordihydroguaiaretic acid (a lipoxygenase inhibitor) had no influence on the effect. Lysophosphatidylcholine (lysoPC) (0.01-5,000 ng/ml), one of the products of phosphatidylcholine by PLA2, dose-dependently enhanced IEC-6 cell migration as well. A combination of PsLA2 (1 U/ml) and lysoPC (1,000 ng/ml) had no additive effect or migration. Moreover, the migration-promoting effect of PLA2 that was blocked by BPB was recovered by lysoPC. After pretreatment of IEC-6 cells with replication-inhibiting doses of mitomycin C, the enhanced migration induced by PLA2 or lysoPC was still observed. These observations suggest that PLA2 may, independently of proliferation, enhance intestinal epithelial cell migration mainly via lysoPC.

Enhanced expression of matrilysin, collagenase, and stromelysin-1 in gastrointestinal ulcers

Programmed expression of several matrix metalloproteinases is an important feature of cutaneous wound healing. To study whether this also applies to gastrointestinal ulcer healing, we used in situ hybridization with 35S-labeled probes to localize sites of collagenase, stromelysin-1, and matrilysin expression in 26 samples representing peptic ulcers, Crohn's disease, and ulcerative colitis. In contrast to skin wounds, collagenase mRNA was not detected in the surface epithelium bordering gastrointestinal ulcer areas. However, together with stromelysin-1 mRNA, it was abundantly expressed by the granulation tissue in all types of ulcers. Signal for matrilysin mRNA and protein was detected in the mucosal epithelium bordering the ulcerations but never in the ulcer stroma. The gut basement membrane was disrupted under the matrilysin-producing epithelial cells as assessed by immunostaining for laminin. Tissue inhibitor of metalloproteinases (TIMP-1) mRNA never co-localized with matrilysin-positive mucosal epithelial cells. These data indicate that matrilysin plays a significant role in epithelial remodelling occurring in gastrointestinal ulcerations whereas collagenase and stromelysin-1 are involved in the reparative processes in the ulcer bed.

Sensitivity and specificity of canine serum total amylase and isoamylase activity determinations

Serum isoamylases were determined prospectively in dogs with pancreatic and extrapancreatic diseases. Mean serum isoamylase determinations were significantly different (p less than 0.05) between normal dogs and dogs with pancreatitis and exocrine pancreatic insufficiency. The sensitivity of serum isoamylase determination exceeded that of total amylase activity for the diagnosis of pancreatitis. Serum isoamylase determinations were less influenced by extrapancreatic diseases compared to total amylase activity when used in the diagnosis of pancreatic disease. Neither serum isoamylase determination nor total amylase activity had adequate sensitivity to support their use in the diagnosis of exocrine pancreatic insufficiency. There were significant (p less than 0.05) linear correlations between isoamylase determinations, total amylase activity, and trypsin-like immunoreactivity concentration.

Intestinal disaccharidase and alkaline phosphatase activities in experimental rabbit mucoid enteropathy

Mucoid enteropathy was induced experimentally by ligation of the cecum, and the activities of mucosal disaccharidases and alkaline phosphatase were measured at different locations along the small intestine of the sick and control rabbits. In the duodenum of rabbits with mucoid enteropathy, the activity of acid beta-galactosidase II was elevated and hetero beta-galactosidase declined. In the jejunum, the activities of lactase, acid beta-galactosidase I and II, hetero beta-galactosidase, trehalase, sucrase and alkaline phosphatase were significantly lower in animals with mucoid enteropathy. In the ileum, acid beta-galactosidase II, hetero beta-galactosidase, maltase, trehalase, sucrase and alkaline phosphatase showed decreased activity in rabbits with mucoid enteropathy.

Wheat-sensitive enteropathy in Irish setter dogs: possible age-related brush border abnormalities

The pathogenesis of a wheat-sensitive enteropathy was explored in a litter bred from two Irish setters with a naturally occurring enteropathy. Jejunal biopsies from all eight progeny exhibited morphological changes comparable to those in the parents, while biochemical abnormalities appeared to be related to age. In biopsies obtained from the first group of four dogs at eight months, the activities of alkaline phosphatase and of leucyl-2-naphthylamidase were almost undetectable while disaccharidases were unaltered. In contrast, analytical subcellular fractionation of biopsies obtained from the second group of four dogs at nine months showed that specific activities now reflected a major deficiency of brush border alkaline phosphatase, and normal brush border leucyl-2-naphthylamidase accompanied by elevated soluble activity. Further studies are indicated to determine whether these findings represent an age-related abnormality affecting specific microvillus membrane proteins.

Enteropathogenic Escherichia coli enteritis: evaluation of the gnotobiotic piglet as a model of human infection

The pathogenicity of classical enteropathogenic Escherichia coli strains of human origin was investigated in gnotobiotic piglets. One to two day old piglets in groups of four were infected perorally with approximately 10(8) colony forming units of one of eight enteropathogenic E coli strains or a non-pathogenic control strain. Animals were necropsied 24 or 48 hours after infection and their intestines were subjected to histological examination, quantitative bacterial culture and estimation of lactase activity. Four enteropathogenic E coli strains caused mild to moderate diarrhoea in nine of the 16 piglets inoculated with them. Piglets given two of these strains later became moribund. One enteropathogenic E coli strain caused a severe illness unaccompanied by diarrhoea. Inflammation of the intestinal mucosa occurred with all eight enteropathogenic E coli strains, but not with the control strain. Pathological changes were most pronounced in the distal ileum and colon and adherent bacteria were seen on the surface of the inflamed mucosa. The extent of the inflammatory response in infected piglets for the most part paralleled the severity of the clinical signs, the degree of bacterial colonisation and the reduction in lactase activity. Electron microscopic examination of tissue from piglets infected with three different strains showed that bacterial adherence to the apical plasma membrane of epithelial cells was accompanied by distinctive ultrastructural changes. These included degeneration of the microvillous brush border, together with cupping and pedestal formation of the plasma membrane at sites of bacterial attachment. The same changes have been seen in naturally occurring enteropathogenic E coli diarrhoea in humans and rabbits. The combined clinical and pathological findings indicate that the neonatal gnotobiotic piglet is a suitable model of infection with enteropathogenic E coli.

[State of the small intestine in rabbits with salmonella infections]

The paper is concerned with the results of morphological and biochemical studies of the duodenum and ileum in young rabbits with salmonellosis. It was shown that all the parts of the small intestine were involved into the pathological process. Enzymopathy developed in the presence of acute catarrhal inflammation and erosive enteritis accompanied by ulceration of necrotized lymph follicles of Peyer's patches of the small intestine. The activity of maltase and alkaline phosphatase was found to be most vulnerable. Of crucial significance in the development of diarrhea in experimental young rabbits were pronounced morphological alterations and derangement of enzyme-forming function in the small intestine.

Clinical aspects of gut enzymology

Enzymological alterations in functional disturbances and in diseases of the intestine are reviewed. Examples are given for diagnostic significance (e.g. in Hirschsprung's and Crohn's diseases), for pathogenetic considerations (e.g. in hypolactasia and in celiac disease), and for secondary involvement of the liver (e.g. in intestinal tumors and after bypass surgery) and are discussed in more detail.

Structural and functional abnormalities of the small intestine in infants and young children with rotavirus enteritis

Structural and functional alterations in duodenal mucosa from 17 children with rotavirus enteritis were assessed. Structural changes were found in specimens from all patients. Patients with the most severe mucosal damage were more likely to require intravenous therapy to correct dehydration. Depression of one or more mucosal disaccharidases was found in 14 of 16 patients. Repeat duodenal biopsy three to eight weeks later in six patients showed marked improvement. The study clearly shows that rotavirus can cause a marked structural and functional lesion in the upper small intestine which is rapidly reversible.

Serum angiotensin-converting enzyme (SACE) in sarcoidosis and other granulomatous disorders

Serum angiotensin-converting enzyme (SACE) activity was significantly higher in 90 patients with sarcoidosis (55 +/- [S.D.] 23 nmol min-1 ml-1) than in 80 healthy controls (34 +/- 9 nmol min-1 ml-1). Steroid therapy modified SACE activity; 60 sarcoidosis patients who were not being treated with steroids had significantly higher enzyme activities (58 +/- 24 nmol min-1 ml-1) than 30 steroid-treated sarcoidosis patients (40 +/- 19 nmol min-1 ml-1). In 50% of the non-steroid treated sarcoidosis patients SACE activity was more than 2 S.D. above the mean value for the controls. SACE activity was measured in 22 tuberculous patients (38 +/- 14 nmol min-1 ml-1), 20 leprosy patients (34 +/- 9 nmol min-1 ml-1), 31 with primary biliary cirrhosis (44 +/- 20 nmol min-1 ml-1), 26 with inflammatory bowel disease (31 +/- 9 nmol min-1 ml-1), 8 with hepatic granulomatous disease, 5 with Hodgkin's disease, and 2 with schistosomiasis. The combined false-positive rate for these non-sarcoidosis patients was 10%. Serial SACE assays provide useful information on the course of sarcoidosis and response to steroid treatment.

[Intestinal enzymopathies of children (author's transl)]

In recent years it has been successfully demonstrated that, in relation to congenital metabolic abnormalities, every enzyme of the gastro-intestinal tract may be absent or inactive.. In serious diseases of the intestinal tract, secondary inactivation of numerous enzymes may result. In this comprehensive presentation the pathology of the disaccharidases, the peptidases and lypolysis is described, the physiology being gone into briefly in each case. Furthermore, all known disturbances of absorption of sugar, aminoacids and fats are briefly dealt with. Finally, congenital chloridorrhea is described.

Alterations of selected intestinal enzymes in hamsters with hamster enteritis syndrome

Portions of duodenum, jejunum, and ileum from 21 hamsters clinically affected with enteritis were examined for enzymes. Utilizing a variety of techniques, the activities of alkaline phosphatase, nonspecific esterases, leucine aminopeptidase, beta-glucuronidase, and methyl green pyroninophilia were determined. The activities of enzymes normally associated with tissue proliferation and active protein synthesis were decreased, whereas those enzymes associated by cytolysis were increased.

Serum lysozyme in Crohn's disease and ulcerative colitis

Serum lysozyme (muramidase) concentrations were determined in patients with different types of inflammatory bowel disease and in normal subjects. The mean (plus or minus S.E.M.) lysozyme concentration for each group was as follows: controls, 8.8 plus or minus 0.3, ulcerative colitis, 9.3 plus or minus 0.6, Crohn's disease, 26.3 plus or minus 1.4. a and bacterial and nonbacterial enteritis, 8.9 plus or minus 0.7 mug per milliliter. Thus, mean enzyme levels were significantly greater in Crohn's disease than in ulcerative colitis (p smaller than 0.001), bacterial and nonbacterial enteritis (p smaller than 0.001) and healthy volunteers (p smaller than 0.001). The elevation of serum lysozyme in Crohn's disease may be related to tissue macrophages because no correlation was found between either the serum lysozyme concentration and the white-cell counts or the absolute numbers of circulating granulocytes or monocytes. Our findings suggest that serum lysozyme may be useful in the differential diagnosis of Crohn's disease from other types of bowel inflammation.