MicroRNA profiling of colon tissue samples following chronic Delta-9-Tetrahydrocannabinol (THC) treatment to chronically SIV-infected rhesus macaques

The study describes miRNA expression in colon tissue following delta 9 tetrahydrocannabinol (Δ9-THC) administration to chronically SIV-infected rhesus macaques. To identify the underlying molecular mechanisms underlying its anti-inflammatory effects, we simultaneously profiled miRNA and mRNA expression in colon of chronically simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs) administered either vehicle (VEH/SIV; n=9) or Δ9- tetrahydrocannabinol (THC; THC/SIV; n=8). Relative to controls, differentially expressed miRNAs were ~2 fold higher in VEH/SIV than THC/SIV RMs. Proinflammatory miR-130a, miR-222 and miR-29b, Lipopolysaccharide-responsive miR-146b-5p and SIV-induced miR-190b were significantly upregulated in VEH/SIV RMs. Compared to VEH/SIV RMs, 10 miRNAs were significantly upregulated in THC-SIV RMs, among which miR-204 was confirmed to directly target MMP8, an extracellular matrix-degrading collagenase that was significantly downregulated in THC/SIV RMs. Moreover, THC/SIV RMs failed to upregulate proinflammatory miR-21, miR-141 and miR-222 and alpha/beta defensins, suggesting attenuated intestinal inflammation. Further, THC/SIV RMs showed higher expression of tight junction proteins (occludin, claudin-3), anti-inflammatory MUC13, keratin-8 (stress protection), PROM1 (epithelial proliferation) and anti-HIV CCL5. Trichrome mason staining detected significant collagen deposition (fibrosis) in the paracortex and B cell follicular zones of axillary lymph nodes from all VEH/SIV but none of the THC/SIV RMs, thus demonstrating the ability of THC to prevent lymph node fibrosis, a serious irreversible consequence of HIV induced chronic inflammation. Furthermore, using flow cytometry, we showed that THC suppressed intestinal T cell proliferation/activation (Ki67/HLADR) and exhaustion (PD1) and increased the percentages of anti-inflammatory CD163+ macrophages. Finally, while THC did not affect CD4+ T cell levels, it significantly reduced CD8+ T cell percentages in blood at 150 and 180 days post SIV infection. These translational findings strongly support a role for differential miRNA/gene induction and T cell activation in THC-mediated suppression of intestinal inflammation in HIV/SIV and potentially other chronic inflammatory diseases of the intestine. Twenty-three age- and weight-matched male Indian rhesus macaques were randomly divided into 3 groups. Group 1 (n=6) remained uninfected. Group 2 (Vehicle only; VEH/SIV, n=9) animals received twice daily intramuscular injections of vehicle and were infected intravenously with 100TCID50 of SIVmac251. Group-3 THC/SIV (n=8) animals received twice daily injections of Δ9-THC and were infected with SIV. Colon tissue was collected at necropsy, ~180 days post SIV infection. ~100 ng of total RNA was first reverse transcribed and preamplified according to the manufacturer’s recommendation. MicroRNA expression profiling was performed using TaqMan ®OpenArray® Human microRNA panels. Data analysis was performed using ExpressionSuite® software. The results from the ExpressionSuite software analysis containing five columns (well, sample, detector, task and CT values) were saved as a tab-delimited text file which was later imported and analyzed using the Omics Office StatMiner qPCR analysis software, TIBCO Spotfire, (Perkin Elmer, Waltham, MA). Omics Office StatMiner Software utilizes the comparative Cτ (ΔΔCτ) method to rapidly and accurately quantify relative gene expression across many genes and samples. miRNA expression data were normalized using the global normalization method and analyzed using the non-parametric Wilcoxon’s rank sum test. Comparisons were made between uninfected and both treatment groups (VEH/SIV and THC/SIV). To determine the effect of chronic THC treatment during SIV infection, comparisons were also made between VEH/SIV and THC/SIV.