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Disruption of colonic barrier function and induction of mediator release by strains of Campylobacter jejuni that invade epithelial cells

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World Journal of Gastroenterology 2008年第48期14卷 7345-7352页

作者： Johannes Beltinger Jo del Buono Maeve M Skelly John Thornley Robin C Spiller William A Stack Christopher J Hawkey Wolfson Digestive Diseases Centre Nottingham University Hospital QMC Campus

AIM: To study the mechanisms by which Campylobacter jejuni (C. jejuni) causes inflammation and diarrhea. In particular, direct interactions with intestinal epithelial cells and effects on barrier function are poorly under- stood. METHODS: To model the initial pathogenic effects of C. jejuni on intestinal epithelium, polarized human colonic HCA-7 monolayers were grown on permeabilized filters and infected apically with clinical isolates of C. jejuni. Integrity of the monolayer was monitored by changes in monolayer resistance, release of lactate dehydrogenase, mannitol fluxes and electron microscopy. Invasion of HCA-7 cells was assessed by a modified gentamicin protection assay, translocation by counting colony forming units in the basal chamber, stimulation of mediator release by immunoassays and secretory responses in monolayers stimulated by bradykinin in an Ussing chamber. RESULTS: All strains translocated across monolayers but only a minority invaded HCA-7 cells. Strains that invaded HCA-7 cells destroyed monolayer resistance over 6 h, accompanied by increased release of lactate dehydrogenase, a four-fold increase in permeability to [3H] mannitol, and ultrastructural disruption of tight junctions, with rounding and lifting of cells off the filter membrane. Synthesis of interleukin (IL)-8 and prostaglandin E2 was increased with strains that invaded the monolayer but not with those that did not. CONCLUSION: These data demonstrate two distinct effects of C. jejuni on colonic epithelial cells and provide an informative model for further investigation of initial host cell responses to C. jejuni.

关键词： Campylobacter jejuni Cell invasion Cellculture chloride secretion Colonocyte HCA-7 cells Membrane permeability Monolayer Mucosal barrier Ussing chamber

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Luminal oxidants selectively modulate electrogenic ion transport in rat colon

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World Journal of Gastroenterology 2006年第34期12卷 5523-5527页

作者： Julio M Mayol Yolanda Adame-Navarrete Pilar Alarma-Estrany Elena Molina-Roldan Fernando Huete-Toral Jesus A Fernandez-Represa Servicio De Cirugia I Hospital Clinico San Carlos Universidad Complutense De Madrid Madrid 28040 Spain

AIM： To investigate the effects of luminal exposure to H2O2 and two related thiol oxidizing agents on basal and stimulated chloride secretion in native colon using electrophysiological and pharmacological approaches. METHODS： Unstripped rat distal colon segments were mounted in Ussing chambers. Potential difference, calculated resistance and short-circuit current across unstripped colon segments were monitored with a dual voltage/current clamp. Paracellular permeability was assessed by measuring the mucosa-to-serosa flux of a fluorescent probe （FITC）. RESULTS： Luminal exposure to hydrogen peroxide transitorily stimulated chloride secretion without altering barrier function. This stimulatory effect could be blocked by basolateral atropine but not indomethacin. The cysteine and methionine oxidizing compounds, phenylarsine oxide and chloramine T respectively, mimicked the effect of H2O2, except for a drop in transcolonic resistance after 30 min. In contrast to the observed stimulatory effect on basal secretion, cAMP-stimulated electrogenic ion transport was blunted by luminal H2O2. However, the Ca^2＋- activated response remained unchanged. CONCLUSION： H2O2 may be an important selective modulator of intestinal ion and water secretion in certain pathologic conditions such as inflammation or ischemiareperfusion by multiple mechanisms.

关键词： chloride secretion Ion transport Rat distal colon Hydrogen peroxide Acetylcholine Atropine

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