Lubiprostone ameliorates the cystic fibrosis mouse intestinal phenotype

<p>Abstract</p> <p>Background</p> <p>Cystic fibrosis (CF) is caused by mutations in the <it>CFTR </it>gene that impair the function of CFTR, a cAMP-regulated anion channel. In the small intestine loss of CFTR function creates a dehydrated, acidic luminal environment which is believed to cause an accumulation of mucus, a phenotype characteristic of CF. CF mice have small intestinal bacterial overgrowth, an altered innate immune response, and impaired intestinal transit. We investigated whether lubiprostone, which can activate the CLC2 Cl^-channel, would improve the intestinal phenotype in CF mice.</p> <p>Methods</p> <p><it>Cftr^tm1UNC</it>(CF) and wildtype (WT) littermate mice on the C57BL/6J background were used. Lubiprostone (10 μg/kg-day) was administered by gavage for two weeks. Mucus accumulation was estimated from crypt lumen widths in periodic acid-Schiff base, Alcian blue stained sections. Luminal bacterial load was measured by qPCR for the bacterial 16<it>S </it>gene. Gastric emptying and small intestinal transit in fasted mice were assessed using gavaged rhodamine dextran. Gene expression was evaluated by Affymetrix Mouse430 2.0 microarray and qRT-PCR.</p> <p>Results</p> <p>Crypt width in control CF mice was 700% that of WT mice (<it>P </it>< 0.001). Lubiprostone did not affect WT crypt width but, unexpectedly, increased CF crypt width 22% (<it>P </it>= 0.001). Lubiprostone increased bacterial load in WT mice to 490% of WT control levels (<it>P </it>= 0.008). Conversely, lubiprostone decreased bacterial overgrowth in CF mice by 60% (<it>P </it>= 0.005). Lubiprostone increased gastric emptying at 20 min postgavage in both WT (<it>P </it>< 0.001) and CF mice (<it>P </it>< 0.001). Lubiprostone enhanced small intestinal transit in WT mice (<it>P </it>= 0.024) but not in CF mice (<it>P </it>= 0.377). Among other innate immune markers, expression of mast cell genes was elevated 4-to 40-fold in the CF intestine as compared to WT, and lubiprostone treatment of CF mice decreased expression to WT control levels.</p> <p>Conclusions</p> <p>These results indicate that lubiprostone has some benefits for the CF intestinal phenotype, especially on bacterial overgrowth and the innate immune response. The unexpected observation of increased mucus accumulation in the crypts of lubiprostone-treated CF mice suggests the possibility that lubiprostone increases mucus secretion.</p

The Influence of Specific Adenylyl Cyclase Isoform Expression on Antidepressant Response

Antidepressant drug development has stagnated and new targets are needed. The literature as a whole does not seem to widely consider the notion of antidepressant action in a way that is both non-canonical and significant or fundamental to the drug's mechanism. Ostensibly, the major available drug classes act through targeting monoamine systems, but the monoamine hypothesis fails to explain many findings in depression and antidepressant effects: How, for example, do cells lacking reputake transporters respond to antidepressants, and in a way that recapitulates the fundamental biochemical deviations seen in depression? Where are these drugs acting, and what factors determine one cell's response to antidepressant drugs vs. another cell's response? A long-standing finding of the Rasenick laboratory describes an effect of antidepressant on G protein systems in vitro, in cell lines such as C6 glioma and PC12 pheochromocytoma, both neuroectodermal derivatives. These cell lines show a predictable response to a variety of commonly used antidepressant compounds and classes. However, not all cell lines, such as HEK293, show these responses. Specifically, the antidepressant-responsive cells show a redistribution of G protein Gs from lipid raft to non-raft membrane fractions with increased functional coupling of Gs and adenylyl cyclase, the reciprocal of changes observed in samples from depressed patients. This redistribution is not accompanied by a change in total membrane Gs content. However, Gi and Gq are unaffected. Biochemically, these changes are evidenced by increases in cAMP production compared to untreated controls, subsequent to stimulation with agonists of GPCR-mediated cAMP production. Yet, these cells do not express the serotonin retupake transporter (SERT) or other monoamine reuptake transporters. It appears that the effect of antidepressants on G protein signaling is non-canonical and does not involve monoamine reuptake or other action at a reuptake transporter. The purpose of this study is to further examine contributors to this antidepressant response, with particular emphasis on cellular adenylyl cyclase isoform expression, to further understanding of antidepressants’ mechanisms of action in the search for newer and better treatments

Electrogastrography reveals post-prandial gastric dysmotility in children with cystic fibrosis

OBJECTIVES: Cystic fibrosis patients have a wide spectrum of gastrointestinal disorders. The aim of this study was to investigate the function of gastroenteric neuromusculature and its response to a prokinetic. METHODS: 14 CF children aged 8.6 + 1.3 years were studied by electrogastrography and compared to 10 age-matched controls. A second recording was performed in CF patients after administration of cisapride (0.3 mg/kg). Parameters analyzed were percentage of normal gastric rhythm (2.0 to 4.0 cpm), percentage of tachygastria (4.0 to 9.0 cpm), dominant frequency instability coefficient and power ratio. RESULTS: CF and control groups were not different in age, height or weight. A significant post-prandial increase in percentage of tachygastria (26.7 + 4.5 versus 12.4 + 2.6; P &lt; 0.05) was seen in CF patients, which was not corrected by cisapride. The power ratio showed a statistical increase in 3 cpm (3.7 + 0.8 versus 1.6 + 0.3; P &lt; 0.05) and in tachygastria (5.3 + 1.2 versus 1.7 + 0.4; P &lt; 0.03) in CF compared with controls. Cisapride had an effect on tachygastria power ratio (3.0 + 0.5; P &lt; 0.04). Analysis of normal rhythm and the dominant frequency instability coefficient were not statistically different in CF and controls. CONCLUSION: This study provides evidence of gastric dysmotility in CF patients

Faecal elastase 1 concentration is a marker of duodenal enteropathy

Background: Measurement of faecal elastase (FE1) is used widely to screen for pancreatic exocrine insufficiency (PI). FE1 does not allow differentiation of primary from secondary PI. Aims: To investigate the relation between duodenal morphology and FE1 in children with secondary PI resulting from primary gastrointestinal diseases. Methods: A group of 51 children underwent small intestinal biopsy and FE1 measurement. Villus to crypt ratio (VCR) and inflammation within the lamina propria of duodenal mucosal biopsy specimens were scored and compared with FE1 values. Results: In 51 children from nine diagnostic categories, a highly significant correlation between FE1 and both duodenal morphology and inflammation was found. Conclusion: Small bowel enteropathy is associated with low FE1 concentrations, indicative of secondary exocrine pancreatic insufficiency

Immunologic significance of respirable atmospheric starch granules containing major birch allergen Bet v 1

Background: Birch-pollen allergens are an important cause of early spring hay fever and allergic asthma. Recently, we reported a mechanism for the release of respirable allergenic particles from birch pollen containing the major allergen Bet v 1. In this study, we aimed to assess the immunologic significance of the released Bet v 1-containing starch granules in the environment.Methods: A two-site monoclonal antibody-based assay (ELISA) was employed to quantitate Bet v 1 in high-volume air sampler filter extracts, and immunogold-labelling was used on sections of these extracts to localize Bet v 1. Immunoblot analyses were performed with pooled sera from patients sensitive to birch pollen.Results: Atmospheric starch granules contained Bet v 1, and the concentration increased upon light rainfall. Sera from patients allergic to birch allergens recognized extracts from isolated starch granules.Conclusions: The clinical implications of these findings are that starch granules released from birch pollen are potentially able to trigger allergic asthmatic reactions to Bet v 1, since the allergen occurs in respirable particles. Thus, clinicians can advise asthma patients to remain indoors on days of light rainfall during the birch-pollen season to avoid high levels of allergen exposure