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Acute depletion of activated memory B cells involves the PD-1 pathway in rapidly progressing SIV-infected macaques.

ABSTRACT: Rapid progression to AIDS is a significant problem, especially in developing countries, where the majority of HIV-infected individuals reside. As rapid disease progression is also frequently observed in SIV-infected macaques, they represent a valuable tool to investigate the pathogenesis of this condition in humans. Here, we have shown that pathogenic SIV infection in rhesus macaques resulted in a rapid depletion (as early as week 2) of activated memory B (CD21-CD27+; mBAct) cells that was strongly associated with rapid disease progression. This depletion was progressive and sustained in rapid progressors, but less severe and transient in typical progressors. Because of the rapid and sustained depletion of mBAct cells, rapid progressors failed to develop SIV-specific Ab responses, showed a decline in non-SIV-specific Ab titers, and succumbed faster to intestinal bacterial infections. Depletion of mBAct cells was strongly associated with preferential depletion of mBAct cells expressing programmed death-1 (PD-1), and in vitro blockade of PD-1 improved their survival. Furthermore, in vivo PD-1 blockade in SIV-infected macaques enhanced Ab responses to non-SIV as well as SIV Ags. Our results identify depletion of mBAct cells as a very early predictor of rapid disease progression in pathogenic SIV infection and suggest an important role for the PD-1 pathway in depletion of mBAct cells and impaired humoral immune responses in SIV-infected macaques.

SUBMITTER: Titanji K

PROVIDER: S-EPMC2964982 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Hyperimmune activation is one of the strong predictors of disease progression during pathogenic immunodeficiency virus infections and is mediated in part by sustained type I interferon (IFN) signaling. Combination antiretroviral therapy suppresses hyperimmune activation only partially in HIV-infected individuals. Here, we show that blockade of Programmed Death-1 (PD-1) during chonic SIV infection significantly reduces the expression of transcripts associated with type I IFN signaling in the blood and colorectal tissue of rhesus macaques (RM). The effect of PD-1 blockade on type I IFN signaling was durable and persisted under high viremia, a condition that is seen in nonprogressive SIV infection in their natural hosts. The reduced type I IFN signaling was associated with enhanced expression of some of the junction-associated genes in the colorectal tissue and a profound decrease in LPS levels in plasma suggesting a possible repair of gut associated junctions and decreased microbial translocation. The reduced type I IFN signaling was also associated with enhanced immunity against gut resident pathogenic bacteria, control of gut associated opportunistic infections and survival of SIV-infected RMs. These results reveal novel mechanisms by which PD-1 blockade enhances survival of SIV-infected RMs and have implications for development of novel therapeutic approaches to control HIV/AIDS. SIV negative controls (n=4); SIV infected and control antibody (SYNAGIS) treated (n=3); and SIV infected Programmed Death 1 antibody (PD-1 Ab) treated (n=3) groups of Rhesus macaques PBMCs were isolated by Ficoll-paque plus medium (Amersham) and were lysed in to RNA later reagent (Qiagen) and samples were homogenized with Qiagen Shredder (Qiagen). RNA was extracted with Rneasy mini kit (Qiagen) and was used for microarray experiments. Rhesus GeneChip assays were performed in the Yerkes Microarray Core Facility (www.microarray.emory.edu), one of the Affymetrix Microarray Core Labs.The 0.5Âµg of total RNA sample was analyzed on Rhesus Macaque Genome GeneChip that consists of over 52,000 probe sets (Affymetrix, Santa Clara, CA). Target RNA labeling, hybridization and post-hybridization processing were performed following the Affymetrix GeneChip Expression Analysis standard protocols. In brief, RNA sample was first reverse-transcribed using T7-Oligo(dT) Promoter Primer and SuperScript II in the first-strand cDNAs synthesis reaction. Following RNase H-mediated second-stranded cDNA synthesis, the double-stranded cDNAs were purified by use of a GeneChip sample clean-up module and served as templates in the generation of biotinylated complementary RNAs (cRNAs) in the presence of T7 RNA Polymerase and a biotinylated nucleotide analog/ribonucleotide mix by in vitro transcription (IVT) reaction. The biotinylated cRNAs were cleaned up, fragmented, and hybridized to the rhesus macaque expression arrays at 45Â°C for 16 h with constant rotation at 60 rpm. The gene chips were then washed and stained with Affymetrix fluidics stations 450 and scanned on Affymetrix scanner 3000. The images are processed to collect raw data with GeneChip Operating Software (GCOS) 1.4.

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Acute depletion of activated memory B cells involves the PD-1 pathway in rapidly progressing SIV-infected macaques.

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