Dataset Information

Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia.

ABSTRACT: Circulating monocytes exhibit an apoptotic resistance phenotype during HIV viremia in association with increased MT expression. MTs are known to play an important role in zinc metabolism and immune function. We now show, in a cross-sectional study using peripheral monocytes, that expression of MT1 isoforms E, G, H, and X is increased significantly in circulating monocyte cells from HIV+ subjects during chronic viremic episodes as compared with uninfected subjects. This increase in expression is also observed during acute viremia following interruption of suppressive ART. Circulating monocytes from HIV+ donors were also found to have elevated zinc importer gene Zip8 expression in conjunction with elevated intracellular zinc levels in contrast to CD4(+)T-lymphocytes. In vitro HIV-1 infection studies with elutriated MDM confirm a direct relation between HIV-1 infection and increased MDM MT1 (isoform G) gene expression and increased intracellular zinc levels. A direct link between elevated zinc levels and apoptosis resistance was established using a cell-permeable zinc chelator TPEN, which reversed apoptosis resistance effectively in monocytes from HIV-infected to levels comparable with uninfected controls. Taken together, increases in MT gene expression and intracellular zinc levels may contribute directly to maintenance of an immune-activated monocyte by mediating an increased resistance to apoptosis during active HIV-1 viremia.

SUBMITTER: Raymond AD

PROVIDER: S-EPMC2924602 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia.

Raymond Andrea D AD Gekonge Bethsebah B Giri Malavika S MS Hancock Aidan A Papasavvas Emmanouil E Chehimi Jihed J Kossenkov Andrew V AV Nicols Calen C Yousef Malik M Mounzer Karam K Shull Jane J Kostman Jay J Showe Louise L Montaner Luis J LJ

Journal of leukocyte biology 20100615 3

Circulating monocytes exhibit an apoptotic resistance phenotype during HIV viremia in association with increased MT expression. MTs are known to play an important role in zinc metabolism and immune function. We now show, in a cross-sectional study using peripheral monocytes, that expression of MT1 isoforms E, G, H, and X is increased significantly in circulating monocyte cells from HIV+ subjects during chronic viremic episodes as compared with uninfected subjects. This increase in expression is ...[more]

PMID: 20551211

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Project description:Steroid-refractory acute rejection is a risk factor for inferior renal allograft outcome. We aimed to gain insight into the mechanisms underlying steroid resistance by identifying novel molecular markers of steroid-refractory acute rejection. Eighty-three kidney transplant recipients (1995-2005), who were treated with methylprednisolone during a first acute rejection episode, were included in this study. Gene expression patterns were investigated in a discovery cohort of 36 acute rejection biopsies, and verified in a validation cohort of 47 acute rejection biopsies. In the discovery set, expression of metallothioneins (MT) was significantly (P<0.000001) associated with decreased response to steroid treatment. Multivariate analysis resulted in a predictive model containing MT-1 as an independent covariate (AUC=0.88, P<0.0000001). In the validation set, MT-1 expression was also significantly associated with steroid resistance (P=0.029). Metallothionein expression was detected in macrophages and tubular epithelial cells. Parallel to the findings in patients, in vitro experiments of peripheral blood mononuclear cells from 11 donors showed that non-response to methylprednisolone treatment is related to highly elevated MT levels. High expression of metallothioneins in renal allografts is associated with resistance to steroid treatment. Metallothioneins regulate intracellular concentrations of zinc, through which they may diminish the zinc-requiring anti-inflammatory effect of the glucocorticoid receptor. Transcriptional profiles of 40 renal allograft biopsy samples were analyzed using Illumina HumanRef-8 v3.0 BeadChips (Illumina, San Diego, CA). Expression profiles were investigated in total RNA isolated from biopsy samples of 18 patients with steroid responsive acute rejection and 18 patients with steroid resistant acute rejection. Four biopsies, taken during acute decrease of graft function but with no histomorphologic indication of rejection, were included as controls.

Project description:Whereas human immunodeficiency virus (HIV) persists in tissue macrophages during antiretroviral therapy (ART), the role of circulating monocytes as HIV reservoirs remains controversial. Three magnetic bead selection methods and flow cytometry cell sorting were compared for their capacity to yield pure CD14+ monocyte populations. Cell sorting by flow cytometry provided the purest population of monocytes (median CD4+ T-cell contamination, 0.06%), and the levels of CD4+ T-cell contamination were positively correlated with the levels of integrated HIV DNA in the monocyte populations. Using cell sorting by flow cytometry, we assessed longitudinally the infection of monocytes and other cell subsets in a cohort of 29 Thai HIV-infected individuals. Low levels of HIV DNA were detected in a minority of monocyte fractions obtained before and after 1 year of ART (27% and 33%, respectively), whereas HIV DNA was readily detected in CD4+ T cells from all samples. Additional samples (2 to 5 years of ART) were obtained from 5 individuals in whom monocyte infection was previously detected. Whereas CD4+ T cells were infected at high levels at all time points, monocyte infection was inconsistent and absent in at least one longitudinal sample from 4/5 individuals. Our results indicate that infection of monocytes is infrequent and highlight the importance of using flow cytometry cell sorting to minimize contamination by CD4+ T cells.IMPORTANCE The role of circulating monocytes as persistent HIV reservoirs during ART is still controversial. Several studies have reported persistent infection of monocytes in virally suppressed individuals; however, others failed to detect HIV in this subset. These discrepancies are likely explained by the diversity of the methods used to isolate monocytes and to detect HIV infection. In this study, we show that only flow cytometry cell sorting yields a highly pure population of monocytes largely devoid of CD4 contaminants. Using this approach in a longitudinal cohort of HIV-infected individuals before and during ART, we demonstrate that HIV is rarely found in monocytes from untreated and treated HIV-infected individuals. This study highlights the importance of using methods that yield highly pure populations of cells as flow cytometry cell sorting to minimize and control for CD4+ T-cell contamination.

Dataset Information

Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia.

Publications

Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia.

Similar Datasets

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