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Increased mucosal neutrophil survival is associated with altered microbiota in HIV infection.

ABSTRACT: Gastrointestinal (GI) mucosal dysfunction predicts and likely contributes to non-infectious comorbidities and mortality in HIV infection and persists despite antiretroviral therapy. However, the mechanisms underlying this dysfunction remain incompletely understood. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species and other potentially harmful effector molecules. Here we used a flow cytometry approach to investigate increased neutrophil lifespan as a mechanism for GI neutrophil accumulation in chronic, treated HIV infection and a potential role for gastrointestinal dysbiosis. We report that increased neutrophil survival contributes to neutrophil accumulation in colorectal biopsy tissue, thus implicating neutrophil lifespan as a new therapeutic target for mucosal inflammation in HIV infection. Additionally, we characterized the intestinal microbiome of colorectal biopsies using 16S rRNA sequencing. We found that a reduced Lactobacillus: Prevotella ratio associated with neutrophil survival, suggesting that intestinal bacteria may contribute to GI neutrophil accumulation in treated HIV infection. Finally, we provide evidence that Lactobacillus species uniquely decrease neutrophil survival and neutrophil frequency in vitro, which could have important therapeutic implications for reducing neutrophil-driven inflammation in HIV and other chronic inflammatory conditions.

SUBMITTER: Hensley-McBain T

PROVIDER: S-EPMC6459500 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Increased mucosal neutrophil survival is associated with altered microbiota in HIV infection.

Hensley-McBain Tiffany T Wu Michael C MC Manuzak Jennifer A JA Cheu Ryan K RK Gustin Andrew A Driscoll Connor B CB Zevin Alexander S AS Miller Charlene J CJ Coronado Ernesto E Smith Elise E Chang Jean J Gale Michael M Somsouk Ma M Burgener Adam D AD Hunt Peter W PW Hope Thomas J TJ Collier Ann C AC Klatt Nichole R NR

PLoS pathogens 20190411 4

Gastrointestinal (GI) mucosal dysfunction predicts and likely contributes to non-infectious comorbidities and mortality in HIV infection and persists despite antiretroviral therapy. However, the mechanisms underlying this dysfunction remain incompletely understood. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species and other potentially harmful effector molecules. Here we used a flow cytometry approach t ...[more]

PMID: 30973942

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Project description:Regardless of infection route, the intestine is the primary site for HIV-1 infection establishment and results in significant mucosal CD4+ T lymphocyte depletion, induces an inflammatory state that propagates viral dissemination, facilitates microbial translocation, and fosters establishment of one of the largest HIV reservoirs. Here we test the prediction that HIV infection modifies the composition and function of the mucosal commensal microbiota.Rectal mucosal microbiota were collected from human subjects using a sponge-based sampling methodology. Samples were collected from 20 HIV-positive men not receiving combination anti-retroviral therapy (cART), 20 HIV-positive men on cART and 20 healthy, HIV-negative men. Microbial composition of samples was analyzed using barcoded 16S Illumina deep sequencing (85,900 reads per sample after processing). Microbial metagenomic information for the samples was imputed using the bioinformatic tools PICRUST and HUMAnN. Microbial composition and imputed function in HIV-positive individuals not receiving cART was significantly different from HIV-negative individuals. Genera including Roseburia, Coprococcus, Ruminococcus, Eubacterium, Alistipes and Lachnospira were depleted in HIV-infected subjects not receiving cART, while Fusobacteria, Anaerococcus, Peptostreptococcus and Porphyromonas were significantly enriched. HIV-positive subjects receiving cART exhibited similar depletion and enrichment for these genera, but were of intermediate magnitude and did not achieve statistical significance. Imputed metagenomic functions, including amino acid metabolism, vitamin biosynthesis, and siderophore biosynthesis differed significantly between healthy controls and HIV-infected subjects not receiving cART.HIV infection was associated with rectal mucosal changes in microbiota composition and imputed function that cART failed to completely reverse. HIV infection was associated with depletion of some commensal species and enrichment of a few opportunistic pathogens. Many imputed metagenomic functions differed between samples from HIV-negative and HIV-positive subjects not receiving cART, possibly reflecting mucosal metabolic changes associated with HIV infection. Such functional pathways may represent novel interventional targets for HIV therapy if normalizing the microbial composition or functional activity of the microbiota proves therapeutically useful.

Project description:Objective: Reg3g has been proposed to have a protective role against infection due to its bactericidal effect on Gram-positive bacteria, but evidence from in vivo studies is lacking. Therefore we generated a Reg3g-/- mouse, to determine its role in intestinal homeostasis and protection against experimental infection. Methods: Reg3g-/- mice were phenotyped using histological methods and a range of innate and immune markers. To investigate the antimicrobial role of Reg3g we experimentally infected mice with Gram-positive Listeria monocytogenes and Gram-negative Salmonella entertitidis and measured translocated bacteria, mucosal and systemic markers of infection. Results: Reg3g-/- mice display altered ileal mucus distribution and increased bacterial contact with the epithelium. , concomitant with This increased the inflammatory status in of the ileal mucosa and increased expression of Il-22, myeloperoxidase (MPO) and serum chemokines in serum. In response to infection, Reg3g-/- mice showed transcriptome changes and elevated levels of mucosal MPO in the ileum, but no increased bacterial translocation to the organs. Conclusions: Reg3g is equally distributed throughout the mucus of wild type (wt) mice and its absence results in an altered distribution of the ileal mucus. Reg3g deficiency also results resulted in increased bacterial contact with the epithelium and heightened inflammatory responses in the ileal mucosa. We propose that Reg3g binds pathogens suggesting it and contributes to mucus barrier function by ensnaring bacteria. Compared to wt mice, Reg3g-/- mice infected with S. enteritidis and L. monocytogenes show an increase of mucosal inflammatory markers indicating the protective, anti-microbial roles of Reg3g in defence against both Gram-positive and -negative bacteria. This study was set up according to a one-treatment, one-control design; treatments were inoculation with either Listeria monocytogenes or Salmonella enteritidis bacterial pathogens. The study results contain transcriptional profiles from infected and sham-infected control C57Bl/6 mice. In total, this study includes data from 2 treatments and 1 control of (pooled) wild-type C57Bl/6 mice and Reg3g-/- KO mutant C57Bl/6 mice = 6 arrays.

Dataset Information

Increased mucosal neutrophil survival is associated with altered microbiota in HIV infection.

Publications

Increased mucosal neutrophil survival is associated with altered microbiota in HIV infection.

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