Intestinal antimicrobial gene expression: impact of micronutrients in malnourished adults during a randomized trial.

BACKGROUND: Because both micronutrients and antimicrobial peptides protect against diarrhea, we looked for an effect on intestinal antimicrobial peptide gene expression during a randomized controlled trial of multiple micronutrient (MM) supplementation. METHODS: Consenting adults (n=287) in Lusaka, Zambia, were randomized to receive a daily MM supplement or placebo and were followed up for 3.3 years, with a crossover after 2 years. Intestinal biopsy samples were obtained at annual intervals, and messenger RNA of the intestinal antimicrobial peptides human alpha defensin (HD) 5, HD6, human beta-defensin (hBD) 1, hBD2, and LL-37 were quantified by real-time reverse-transcriptase polymerase chain reaction. Samples were also obtained during diarrhea episodes and after convalescence. RESULTS: There was no effect overall of treatment allocation. However, in malnourished adults (body mass index < or =18.5), HD5 mRNA was increased by 0.8 log transcripts/microg total RNA in MM recipients, compared with HD5 mRNA in placebo recipients (P=.007). During diarrhea, HD5 expression was reduced by 0.8 log transcripts in placebo recipients (P=.02) but was not reduced in MM recipients, nor was it reduced after the crossover. Correlations between HD5 and nutritional status were found that were sex-specific but not explained by serum leptin or adiponectin concentrations. CONCLUSIONS: Micronutrient supplementation was associated with up-regulation of HD5 only in malnourished adults. Interactions between antimicrobial gene expression and nutritional status may help to explain the increased risk of infection in individuals with malnutrition.

Plasma citrulline as a quantitative biomarker of HIV-associated villous atrophy in a tropical enteropathy population.

BACKGROUND & AIMS: Studies have shown that the circulating citrulline concentration is decreased in patients with proximal small bowel villous atrophy from coeliac disease and more so in patients with extensive damage to the intestinal mucosa, but there have been few data on HIV enteritis and tropical enteropathy (TE). Our primary aim was to correlate serum citrulline with the degree of reduction of the enterocyte mass in HIV-infected patients with TE. METHODS: Postabsorptive fasting serum citrulline was measured in 150 TE pts, 44 of whom had HIV infection, using reverse phase, high performance liquid chromatography. Absorptive capacity and permeability were measured after intrajejunal instillation of 4 sugars (5 g lactulose, 1 g L-rhamnose, 0.5 g D-xylose, 0.2 g 3-O methyl D glucose) with assay by thin-layer chromatography. Morphometric analysis was carried out on jejunal biopsies. RESULTS: In HIV positive patients, the median serum citrulline was significantly lower (median 19, interquartile range (IQR) 17-24 µmol/L) than in HIV negative patients (median 27, IQR 23-33 µmol/L; p < 0.001). There were statistically significant correlations (p < 0.005) between citrulline and: crypt depth; villous height/crypt depth ratio; Shenk-Klipstein score; and xylose absoption, only in the HIV positive. CONCLUSIONS: Serum citrulline concentration appears to be a quantitative biomarker of small bowel mass integrity in HIV positive enteropathy and deserves assessment as a surrogate for monitoring anti-retroviral therapy.

Gastric and intestinal barrier impairment in tropical enteropathy and HIV: limited impact of micronutrient supplementation during a randomised controlled trial.

BACKGROUND: Although micronutrient supplementation can reduce morbidity and mortality due to diarrhoea, nutritional influences on intestinal host defence are poorly understood. We tested the hypothesis that micronutrient supplementation can enhance barrier function of the gut. METHODS: We carried out two sub-studies nested within a randomised, double-blind placebo-controlled trial of daily micronutrient supplementation in an urban community in Lusaka, Zambia. In the first sub-study, gastric pH was measured in 203 participants. In the second sub-study, mucosal permeability, lipopolysaccharide (LPS) and anti-LPS antibodies, and serum soluble tumour necrosis factor receptor p55 (sTNFR55) concentrations were measured in 87 participants. Up to three stool samples were also analysed microbiologically for detection of asymptomatic intestinal infection. Gastric histology was subsequently analysed in a third subset (n = 37) to assist in interpretation of the pH data. Informed consent was obtained from all participants after a three-stage information and consent process. RESULTS: Hypochlorhydria (fasting gastric pH > 4.0) was present in 75 (37%) of participants. In multivariate analysis, HIV infection (OR 4.1; 95%CI 2.2-7.8; P < 0.001) was associated with hypochlorhydria, but taking anti-retroviral treatment (OR 0.16; 0.04-0.67; P = 0.01) and allocation to micronutrient supplementation (OR 0.53; 0.28-0.99; P < 0.05) were protective. Hypochlorhydria was associated with increased risk of salmonellosis. Mild (grade 1) gastric atrophy was found in 5 participants, irrespective of Helicobacter pylori or HIV status. Intestinal permeability, LPS concentrations in serum, anti-LPS IgG, and sTNFR55 concentrations did not differ significantly between micronutrient and placebo groups. Anti-LPS IgM was reduced in the micronutrient recipients (P <0.05). CONCLUSIONS: We found evidence of a specific effect of HIV on gastric pH which was readily reversed by anti-retroviral therapy and not mediated by gastric atrophy. Micronutrients had a modest impact on gastric pH and one marker of bacterial translocation. TRIAL REGISTRATION: Current Controlled Trials ISRCTN31173864.