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

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 [(3)H] mannitol, and ultrastructural disruption of tight junctions, with rounding and lifting of cells off the filter membrane. Synthesis of interleukin (IL)-8 and prostaglandin E(2) 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.

Evaluation of faecal occult blood test and lactoferrin latex agglutination test in screening hospitalized patients for diagnosing inflammatory and non-inflammatory diarrhoea in Dhaka, Bangladesh.

BACKGROUND: Inflammatory diarrhoea (ID) resulting from Shigella, Salmonella, Campylobacter and Entamoeba histolytica requires specific diagnosis for therapy. Differentiation between ID and non-inflammatory diarrhoea (NID) is often not clinically possible. A faecal occult blood test (FOBT) correlates with faecal leucocytes. Lactoferrin indicates an inflammatory process as a marker for faecal leucocytes. We evaluated diagnostic values of lactoferrin latex agglutination test (LT) either alone or in combination with FOBT, correlating with stool microscopy and microbiology in differentiating ID from NID. METHODS: The study population constituted patients enrolled in 2% systematic sampling of patients under Diarrhoeal Disease Surveillance System of Dhaka Hospital, ICDDR,B. RESULTS: Between July and November 2002, 594 patients were enrolled; evaluation of FOBT and LT were done in 448/594 (75%) patients from whom either a single enteropathogen (315/594, 53%) or no pathogen (133/594, 22%) were identified and 146 were excluded for multiple pathogens. Invasive and non-invasive pathogens were isolated from 24% and 76% of the patients. FOBT and LT were positive in 40% and 39% of the samples. The sensitivities, specificities, PPVs, NPVs, and accuracies of FOBT were 55, 63, 24, 87 and 62%, and LT were 52, 64, 23, 86 and 62%, respectively. CONCLUSION: FOBT and LT are not useful in differentiating ID from NID in diarrhoeal patients in Dhaka, Bangladesh.

Mechanisms of venoocclusive disease resulting from the combination of cyclophosphamide and roxithromycin.

BACKGROUND: High doses (>or=500 mg/m) of cyclophosphamide are known to cause venoocclusive disease (VOD). The authors recently observed a patient treated with immunosuppressive cyclophosphamide doses (100 mg/day) and roxithromycin who developed VOD. Because roxithromycin inhibits cytochrome P450 (CYP) 3A4 and P-glycoprotein, the patient may have been exposed to higher cyclophosphamide and/or cyclophosphamide metabolite concentrations. METHODS: The effect of roxithromycin on the metabolism and toxicity of cyclophosphamide was studied using human hepatic microsomes and a human endothelial cell line. RESULTS: Cyclophosphamide or roxithromycin at concentrations from 0.05 to 500 micromol/L were not toxic to endothelial cells as assessed by lactate dehydrogenase (LDH) leakage assay. However, the combination of roxithromycin (500 micromol/L) and cyclophosphamide was toxic for all the tested cyclophosphamide concentrations (0.05 to 500 micromol/L) without clear concentration dependence (LDH ratio 38.3 +/- 11.0 [mean +/- SEM] for the combination with cyclophosphamide 0.05 micromol/L and 50.2 +/- 10.2 for the combination with cyclophosphamide 500 micromol/L; P

Hepatic veno-occlusive disease associated with immunosuppressive cyclophosphamide dosing and roxithromycin.

OBJECTIVE: To report on a patient developing hepatic veno-occlusive disease while being treated with immunosuppressive doses of cyclophosphamide (< or =2 mg/kg). CASE SUMMARY: A 66-year-old woman with autoimmune hemolytic anemia developed hepatic veno-occlusive disease while being treated with immunosuppressive cyclophosphamide 100 mg/day in combination with roxithromycin (total dose 600 mg/day). After all drugs were stopped, the patient recovered within 2 weeks. The Naranjo probability scale indicated a probable relationship between veno-occlusive disease and treatment with cyclophosphamide in this patient. DISCUSSION: Since roxithromycin inhibits CYP3A4, which is involved with cyclophosphamide metabolism, a drug-drug interaction could have been responsible. In addition, roxithromycin is an inhibitor of the drug transporter P-glycoprotein, possibly leading to accumulation of cyclophosphamide in endothelial cells. Alternatively, since cyclophosphamide has been reported to induce apoptosis, roxithromycin could have rendered endothelial cells more vulnerable for apoptosis. CONCLUSIONS: In specific patients, cyclophosphamide can be associated with hepatic veno-occlusive disease at immunosuppressive doses.