Unknown,Transcriptomics,Genomics,Proteomics

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Early SIV infection and effects of pathogenic and commensal enteric bacteria on expression in ileum tissue

ABSTRACT: We used the ileal loop model to assess the effects of enteric bacteria organisms on host gene expression in intestinal tissue independent of and following early SIV infection. SIV infection in the gut causes rapid and severe immune dysfunction and damage to the intestinal structure, this may alter the intimate interaction with lumenal organisms. This study was performed to determine whether early SIV infection, prior to the depletion of CD4+ T cells, can alter interaction of the host with pathogenic Salmonella serovar Typhimurium (ST) or commensal Lactobacillus plantarum (LP), and to further understand the earliest changes to the intestinal mucosa following SIV infection. We used microarray analysis to detail the global program of gene expression underlying changes in the ileum following early SIV infection, and if these changes in any way alter the host interaction/ response to pathogenic and commensal enteric bacteria. A subset of animals were infected with SIVmac251 for 2.5 days, following which they underwent a loop surgery where the ileum was sectioned off with surgical ties and bacteria (ST or LP) or their respective media controls (LB or MRS) were injected intralumenally. Following 5 hours of incubation the loops were excised and frozen. Tissue sections were cut and RNA extracted for gene expression analysis. Rhesus Macaques infected with SIVmac251 for 2.5 days compared to uninfected controls. Comparisons are of ileum loop sections injected with Salmonella serovar Typhimurium, Lactobacillus Plantarum or respective media controls LB or MRS.

ORGANISM(S): Macaca mulatta

SUBMITTER: Satya Dandekar

PROVIDER: E-GEOD-52589 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Epithelial cells of the mammalian intestine are covered with a mucus layer that prevents direct contact with intestinal microbes but also constitutes a substrate for mucus-degrading bacteria. To study the effect of mucus degradation on the host response, germ-free mice were colonized with Akkermansia muciniphila. This anaerobic bacterium belonging to the Verrucomicrobia is specialized in the degradation of mucin, the glycoprotein present in mucus, and found in high numbers in the intestinal tract of human and other mammalian species. Efficient colonization of A. muciniphila was observed with highest numbers in the cecum, where most mucin is produced. In contrast, following colonization by Lactobacillus plantarum, a facultative anaerobe belonging to the Firmicutes that ferments carbohydrates, similar cell-numbers were found at all intestinal sites. Whereas A. muciniphila was located closely associated with the intestinal cells, L. plantarum was exclusively found in the lumen. The global transcriptional host response was determined in intestinal biopsies and revealed a consistent, site-specific, and unique modulation of about 750 genes in mice colonized by A. muciniphila and over 1500 genes after colonization by L. plantarum. Pathway reconstructions showed that colonization by A. muciniphila altered mucosal gene expression profiles toward increased expression of genes involved in immune responses and cell fate determination, while colonization by L. plantarum led to up-regulation of lipid metabolism. These indicate that the colonizers induce host responses that are specific per intestinal location. In conclusion, we propose that A. muciniphila modulates pathways involved in establishing homeostasis for basal metabolism and immune tolerance toward commensal microbiota. Keywords: Analysis of target gene regulation by using microarrays Adult germ-free female NMRI-KI mice (45 – 65 days) were used for bacterial mono-association. Two bacterial strains were used in this study, A. muciniphila MucT (ATTC BAA-835) and L. plantarum WCFS1 (NCIMB 8826). A. muciniphila was grown anaerobically in a basal mucin based medium and L. plantarum was grown anaerobically at 37°C in Man-Rogosa-Sharpe broth (MRS; Le Pont de Claix, France). After 7 days of colonization, mice were killed by cervical dislocation and terminal ileum, cecum and ascending colon specimens were sampled.

Project description:The study describes miRNA expression in intact duodenum following chronic delta 9 tetrahydrocannabinol (M-NM-^T9-THC) administration to SIV-infected rhesus macaques. Chronic M-NM-^T9-THC administration to uninfected macaques significantly and positively modulated intestinal miRNA expression by increasing the total number of differentially expressed miRNAs from 14 to 60 days post infection (DPI). At 60DPI, ~28% of miRNAs showed decreased expression in VEH/SIV compared to none in the THC/SIV group. Furthermore, compared to the VEH/SIV group, THC selectively upregulated the expression of miR-10a, miR-24, miR-99b, miR-145, miR-149 and miR-187 previously shown to target proinflammatory molecules. NOX4, a potent reactive oxygen species generator was confirmed as a direct miR-99b target. A significant increase in NOX4+ crypt epithelial cells was detected in VEH/SIV compared to the THC/SIV group. We speculate that miR-99b-mediated NOX4 downregulation may protect the intestinal epithelium from oxidative stress-induced damage. Twelve age and weight matched male Indian rhesus macaques were randomly divided into 4 groups. Group 1 (n=1) received vehicle (1:1:18 of emulphor : alcohol : saline) and no infection. Group 2 (THC only, n=3) animals received twice daily intramuscular injections of M-NM-^T9-THC and no infection. Group-3 THC/SIV, (n=4) animals received twice daily injections of vehicle and were infected intravenously with 100TCID50 of SIVmac251. Group-4 (VEH/SIV, n=4) animals received twice daily injections of M-NM-^T9-THC similar to group 1 for four weeks prior to SIV infection. Duodenal pinch biopsies were collected before infection and thereafter at 14 and 30 days post infection. All animals were necropsied at 60 days post SIV infection. ~100 ng of total RNA was first reverse transcribed and preamplified according to the manufacturerM-bM-^@M-^Ys recommendation. microRNA expression profiling was performed using TaqMan M-BM-.OpenArrayM-BM-. Human microRNA panels. Data analysis was performed using ExpressionSuiteM-BM-. software. Data was normalized to three endogenous controls (RNU44, RNU48 and snoU6). Delta CT values were calculated by subtracting individual miRNA CT values from an average of all three endogenous controls. Comparisons were made between preinfection and all three treatment groups at 14, 30 and 60 DPI. To determine the effect of chronic THC treatment during SIV infection, comparisons were also made between VEH/SIV and THC/SIV at all three time points.

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Early SIV infection and effects of pathogenic and commensal enteric bacteria on expression in ileum tissue

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