The Inhibition Effect Of HIV-gp120and Tat On TLR-9-induced Activion In Plasmacytoid Dendritic Cells

AIDS remains a wold threaten to the health of all mankind, prompting researchers rushed into the diagnosis and treatment of AIDS, although they achieved some results, but still can not effectively control the eradication,of AIDS in the world, so we still need to make persistent efforts to study the mechanism of AIDS and thus provide a new theoretical basisfor the development of new drugs.HIV-1envelope protein gp120plays an important role in virus infection. In the process of the virus into the cell, the combination of gp120and CD4molecules lead to conformational change, the fusion of viral envelope and cell membrane and then infect cells. Tat protein is activated as a trans-acting factors plays an important role in the process of HIV gene repliction, the basic area and core area of tat play a key role in the trans-activation.HIV infection mainly attacks the CD4+T cells, the impact of the HIV envelope protein (tgp120) and accessory proteins (tat) on the number and function of CD4+T cells has been studied more thoroughly. In recent years, the relationship between peripheral dendritic cells (pDC) and HIV was more and more attentioned by researchers.but recently studies have shown that HIV can also attack other cells, such as peripheral dendritic cells (pDC), their play central role in both innate and adaptive antiviral immune responses, pDCs are the principal producers of Type1interferons.These cytokines exhibit potent antiviral activity insofar as they regulate the responses of numerous cell subsets involved in both innate and adaptive immune responses against viral pathogens[1]. pDC can also produce other cytokines:as IL-6, TNF-a, IP-10, these cytokines play important role in anti-virus and regulating the immune response. Meanwhile, the DC can also express its rich costimulatory molecules (CD80/B7-1CD86/B7-2, CD40, CD40L, etc.) to provide the necessary second signal for T cell activation, which initiates an immune response. In addition, pDC increase cytotoxicity of NK cell by producing type1interferons.HIVinfection results in a decrease in the number of circulating pDCs[2-3]. Levels of circulating pDCs correlate inversely with plasma viral load and directly with CD4T cell counts[3-4]. These effects can be partially reversed by antiretroviral therapy [5].The underlying cause(s) of these alterations in pDC numbers and activity, as a result of HIV infection, are unknown.Toll-like receptors (TLRs) mainly expressed in dendritic cells and macrophages,an important class of pattern recognition receptors,can selectively recognize pathogen-associated molecular patterns,as a immune system’s first barrier against pathogen invasion.TLR play an important role in the innate immune response, can well control the nature,duration, and intensity.of the inflammatory response, TLR9(Toll-LikeReceptor9) mainly expressed by pDCs, has an important regulatory role in pDC function[6-7].When TLR9stimulated by irritants (CpG-A), the expression of interferon and other cytokines (IL-6, TNF-alpha,IP-10) are increased in pDC, in addition,the expression of surface costimulatory molecules and MHC class Ⅱ molecule are increased, thus contributing to DC maturation, lead to antigen specific immune response, especially the generation of Thl-type response, and thus to mediate the strength and type of acquired immune responses, connect the innate immune response and acquired immune response.At present, the HIV-1structural protein gpl20and the main regulatory protein Tat,the impact of these two proteins in the function and counts of CD4+T cells is studied thoroughly, but currently whether these proteins can influence and regulate the DC differentiation and maturation of is not very clear, rarely reported in the literature.so understand how the HIV proteins (Tat,, gp120) affect the function of pDCs,willgive us a preliminary understanding of pDC may play an important role in the process of HIV immunocompromised. In this paper, we first isolated and purified out of pDCs, stimulated with CpG-A and then with or without the gp120and Tat, to analyze the secretion of cytokines and expression of CD molecules in pDCs, as well as the killing activity of NK cells,willgive us a preliminary understanding of pDC may play an important role in the process of HIV immunocompromised.The Inhibition effect of HIV-gp120and Tat on CPG-A-induced activion in plasmacytoid dendritic cellsObjective:To study the mechanisms that plasmacytoid dendritic cells (pDCs) interact with and respond to HIV, then provide fundamental insights into HIV pathogenesis, hold promise for preventative and even curative strategies.Methods:pDCs were isolated by a BDCA-4dendritic cell isolation kit and its purity was analyzed using flow cytometry. pDcs and PBMCs were stimulated by CpG-A, gp120, tat or CpG-A concomitant treatment with gp120or tat. The expressions of type Ⅰ IFNs and other inflammatory cytokines, including TNF-α, IL-6and IP-10in the culture supernatant were determined by ELISA. In addition,when detect IFN-a and IFN-(3, we also added a PBMC served as controls.The expressions of CD40,CD54,CD80,CD86in pDCs were analyzed by ELISA. NK Cell Cytotoxicity was determined by LDH.Results:(1) Before separation the purity of pDCs is0.41%, after separation the purity of pDCs is up to85.11%.(2) In pDCs, CpG-A can significantly induce high levels of type Ⅰ IFNs which can be inhibited by gp120or tat. The similar results were showed in treated PBMCs. P<0.05CpGA VSCpG-A+gp120and CpGA VS CpG-A+tat (3)In pDCs, CpG-A can significantly induce high levels of TNF-α,IL-6and IP-10which can be inhibited by gP120or tat..P<0.05CpGA VSCpG-A+gP120and CpGA VS CpG-A+tat(4)In pDCs,CpG-A can significantly induce high levels ofCD40,CD54,CD80,CD86which can be inhibited by gP120or tat..P<0.05CpGA VSCpG-A+gP120and CpGA VS CpG-A+tat(5)In pDCs,CpG-A can significantly induce NK Cell Cytotoxicity which can be inhibited by gP120or tat..P<0.05CpGA VSCpG-A+gP120and CpGA VS CpG-A+tatConelusion:(1)CpG-A can significantly induce high levels of type Ⅰ IFNs,TNF一α,IL-6,IP-10, CD40,CD54,CD80,CD86,and enhance NK Cell Cytotoxicity.(2)Gp120and tat can effectively inhibit CpG-A-mediated actiVion in pDCs and then lead to HIV immune deficiency and immune escape,aggravate progression of AIDS. This may provides a new way of thinking to the pathogenesis of AIDS.