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Objective: The aim of this study was to investigate the kinetics of Env (gp140)-specific antibody-secreting cells (ASCs) during acute and early chronic simian immunodeficiency virus (SIV) infection, and prior to and postantiretroviral therapy (ART) in rhesus macaques., Design and Methods: At week 0, rhesus macaques were inoculated intravenously with SIVmac239 and the viral loads were allowed to develop. Daily ART was initiated at week 5 post infection until week 18, though the animals were monitored until week 28 for the following parameters: enumeration of SIV gp140-specific ASCs by ELISPOT; quantification of viremia and SIV gp140-specific IgG titres through qRT-PCR and ELISA, respectively; estimation of monocytes, follicular helper T cells (Tfh) and memory B cell frequencies using polychromatic flow cytometry., Results: Direct correlations were consistently found between blood SIV gp140-specific ASC responses and viremia or SIV Env-specific IgG titres. In contrast, SIV gp140-specific ASC responses showed inverse correlations with the percentage of total memory B cells in the blood. In lymph nodes, the magnitude of the SIV gp140-specific ASC responses also followed the viral load kinetics. In contrast, the number of SIV gp140-specific ASCs presented did not correlate with frequencies of circulating activated monocyte (CD14+CD16+) or Tfh cells., Conclusion: Blood and/or lymph node viral loads may regulate the onset and magnitude of SIV gp140-specific ASCs during SIV infection and following ART in rhesus macaques., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Human gut-associated lymphoid tissues (GALT) play a key role in the acute phase of HIV infection. The propensity of HIV to replicate in these tissues, however, is not fully understood. Access and migration of naive and memory CD4 + T cells to these sites is mediated by interactions between integrin α 4 β 7 , expressed on CD4 + T cells, and MAdCAM, expressed on high endothelial venules. We report here that MAdCAM delivers a potent costimulatory signal to naive and memory CD4 + T cells following ligation with α 4 β 7 . Such costimulation promotes high levels of HIV replication. An anti-α 4 β 7 mAb that prevents mucosal transmission of SIV blocks MAdCAM signaling through α 4 β 7 and MAdCAM-dependent viral replication. MAdCAM costimulation of memory CD4 + T cells is sufficient to drive cellular proliferation and the upregulation of CCR5, while naive CD4 + T cells require both MAdCAM and retinoic acid to achieve the same response. The pairing of MAdCAM and retinoic acid is unique to the GALT, leading us to propose that HIV replication in these sites is facilitated by MAdCAM-α 4 β 7 interactions. Moreover, complete inhibition of MAdCAM signaling by an anti-α 4 β 7 mAb, an analog of the clinically approved therapeutic vedolizumab, highlights the potential of such agents to control acute HIV infection.

The GI tract is preferentially targeted during acute/early HIV-1 infection. Consequent damage to the gut plays a central role in HIV pathogenesis. The basis for preferential targeting of gut tissues is not well defined. Recombinant proteins and synthetic peptides derived from HIV and SIV gp120 bind directly to integrin α4β7, a gut-homing receptor. Using both cell-surface expressed α4β7 and a soluble α4β7 heterodimer we demonstrate that its specific affinity for gp120 is similar to its affinity for MAdCAM (its natural ligand). The gp120 V2 domain preferentially engages extended forms of α4β7 in a cation -sensitive manner and is inhibited by soluble MAdCAM. Thus, V2 mimics MAdCAM in the way that it binds to α4β7, providing HIV a potential mechanism to discriminate between functionally distinct subsets of lymphocytes, including those with gut-homing potential. Furthermore, α4β7 antagonists developed for the treatment of inflammatory bowel diseases, block V2 binding to α4β7. A 15-amino acid V2 -derived peptide is sufficient to mediate binding to α4β7. It includes the canonical LDV/I α4β7 binding site, a cryptic epitope that lies 7-9 amino acids amino terminal to the LDV/I, and residues K169 and I181. These two residues were identified in a sieve analysis of the RV144 vaccine trial as sites of vaccine -mediated immune pressure. HIV and SIV V2 mAbs elicited by both vaccination and infection that recognize this peptide block V2-α4β7 interactions. These mAbs recognize conformations absent from the β- barrel presented in a stabilized HIV SOSIP gp120/41 trimer. The mimicry of MAdCAM-α4β7 interactions by V2 may influence early events in HIV infection, particularly the rapid seeding of gut tissues, and supports the view that HIV replication in gut tissue is a central feature of HIV pathogenesis., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: JA, CC and ASF are inventors of patent 20160075786 submitted by the NIAID, NIH that covers the study of reagents that serve as antagonists of the interaction between HIV gp120 and α4β7 mAb. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Purpose of Review: Acute HIV infection is characterized by high-level viral replication throughout the body's lymphoid system, particularly in gut-associated lymphoid tissues resulting in damage to structural components of gut tissue. This damage is irreversible and believed to contribute to the development of immune deficiencies. Antiretroviral therapy (ART) does not restore gut structure and function. Studies in macaques point to an alternative treatment strategy that may ameliorate gut damage. Integrin α 4 β 7 mediates the homing of lymphocytes to gut tissues. Vedolizumab, a monoclonal antibody (mAb) antagonist of α 4 β 7 , has demonstrated efficacy and has been approved for the treatment of inflammatory bowel disease in humans. Here, we describe our current knowledge, and the gaps in our understanding, of the role of α 4 β 7 in HIV pathogenesis and treatment., Recent Findings: When administered to macaques prior to infection, a nonhuman primate analogue of vedolizumab prevents transmission of SIV. In combination with ART, this mAb facilitates durable virologic control following treatment interruption. Targeting α 4 β 7 represents a novel therapeutic approach to prevent and treat HIV infection.

Background: Small chemical compounds which target chemokine receptors have been developed against human immunodeficiency virus type 1 (HIV-1) and are under investigation for use as anti-HIV-1 microbicides. In addition, monoclonal antibodies (mAbs) against chemokine receptors have also been shown to have anti-HIV-1 activities. The objective of the present study was to screen a panel of three anti-CXCR4 specific monoclonal antibodies (mAbs) for their ability to block the HIV-1 infection using in vitro activated primary peripheral blood mononuclear cells (PBMCs)., Results: PBMCs from normal donors were pre-activated with anti-CD3 and anti-CD28 mAbs for 1 day, and aliquots were infected with a low dose of CCR5-tropic (R5), CXCR4 tropic (X4) or dual tropic (X4R5) HIV-1 isolates and cultured in the presence of a panel of anti-CXCR4 mAbs. The panel included clones A145 mAb against the N-terminus, A120 mAb against a conformational epitope consisting of extracellular loops (ECL)1 and ECL2, and A80 mAb against ECL3 of CXCR4. Among these mAbs, the A120 mAb showed the most potent inhibition of infection, by not only X4 but surprisingly also R5 and X4R5 HIV-1. The inhibition of R5 HIV-1 was postulated to result from the novel ability of the A120 mAb to induce the levels of the CCR5-binding β-chemokines MIP-1α, MIP-1β and/or RANTES, and the down modulation of CCR5 expression on activated CD4+ T cells. Neutralizing anti-MIP-1α mAb significantly reversed the inhibitory effect of the A120 mAb on R5 HIV-1 infection., Conclusions: The data described herein have identified a unique epitope of CXCR4 whose ligation not only directly inhibits X4 HIV-1, but also indirectly inhibits R5 HIV-1 infection by inducing higher levels of natural CCR5 ligands.

To elucidate the immunological role for the costimulatory molecule OX40 against the early stage of HIV-1 infection, fresh peripheral blood mononuclear cells (PBMCs) from normal donors were stimulated with immobilized anti-CD3 monoclonal antibody (mAb) together with soluble anti-CD28 mAb for 24 h, infected with CCR5-tropic (R5) HIV-1, and then cocultured in the presence or absence of OX40 ligand (OX40L). Results of these studied showed that OX40 stimulation led to a marked reduction in levels of p24, the frequency of intracellular p24(+) cells, as well as HIV-1-mediated syncytium formation. The suppression was reversed by anti-OX40L mAb. The mechanism underlying the R5 HIV-1 suppression was shown to be mediated in part by the CCR5-binding β-chemokines RANTES, MIP-1α, and MIP-1β, since the effect of the OX40 stimulation was reversed by a neutralizing antibody mixture against these three β-chemokines. Thus, OX40 stimulation enhanced the production of these CCR5-binding β-chemokines by the activated PBMCs and subsequently down-modulated CCR5 expression on the activated CD4(+) T cells. Taken together, the present data revealed a new role for OX40 in HIV-1 infection and documents the fact that OX40 stimulation suppresses the infection of primary activated PBMCs with R5 HIV-1 via enhanced production of R5 HIV-1 suppressing β-chemokines.

In an attempt to simplify the protocol of DC generation in vitro, studies conducted herein show that functional DCs could be generated from bulk peripheral blood mononuclear cells (PBMCs) in media containing GM-CSF and IL-4. Interestingly, when PBMCs, but not purified monocytes, were exposed to either CCR5- or CXCR4-tropic inactivated HIV-1 isolates (iHIV-1) at the initiation of the culture, DC yields were significantly reduced in a dose-dependent manner because of monocyte apoptosis. Similar impairment of DC generation was noted using type I IFNs and poly IC not only in cultures of PBMCs but also using highly enriched monocytes. This effect was reversed by antihuman type I IFN receptor, but not by anti-FasL, anti-TRAIL, anti-TNF, or a mixture of these antibodies. iHIV-1-exposed PBMCs, but not monocytes, produced high levels of IFN-alpha but not IFN-beta. PBMCs depleted of CD123(+) plasmacytoid DCs produced low levels of IFN-alpha and were resistant to iHIV-1-mediated DC impairment. Interestingly, exogenously added TNF reversed the impairment by iHIV-1 in the PBMC cultures. In conclusion, the present results indicate that iHIV-1 impairs the in vitro generation of functional DCs from PBMCs through the induction of IFN-alpha from plasmacytoid DCs in a CD4-dependent fashion in the absence of TNF., (Copyright 2010 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Progenitor mast cells (prMCs), derived from CD34(+) precursors are CD4(+)/CCR5(+)/CXCR4(+) and susceptible to CCR5(R5)-tropic virus but only marginally susceptible to CXCR4(X4)-tropic HIV. As infected prMCs mature within extravascular compartments, they become both latently infected and HIV-infection resistant, and thus capable of establishing an inducible reservoir of CCR5-tropic infectious clones. In this report we provide the first evidence that IgE-FcepsilonRI interactions, occurring during a unique period of mast cell (MC) ontogeny, enhance prMC susceptibility to X4 and R5X4 virus. IgE-FcepsilonRI interactions significantly increased expression of CXCR4 mRNA ( approximately 400- to 1800-fold), enhanced prMC susceptibility to X4 and R5X4 virus ( approximately 3000- to 16,000-fold), but had no significant effect on CD4, CCR3, or CCR5 expression, susceptibility to R5 virus, or degranulation. Enhanced susceptibility to infection with X4 virus occurred during the first 3-5 wk of MC ontogeny and was completely inhibited by CXCR4-specific peptide antagonists and omalizumab, a drug that inhibits IgE-FcepsilonRI interactions. IgE-FcepsilonRI coaggregation mediated by HIVgp120 or Schistosoma mansoni soluble egg Ag accelerated maximal CXCR4 expression and susceptibility to X4 virus by prMCs. Our findings suggest that for HIV-positive individuals with atopic or helminthic diseases, elevated IgE levels could potentially influence the composition of CXCR4-tropic and R5X4-tropic variants archived within the long-lived tissue MC reservoir created during infection.

This autopsy study evaluates the possible cumulative effects of cocaine use in HIV-infected adult individuals on cardiovascular tissue. A total of 187 autopsy case reports and available H&E sections of myocardium and coronary arteries were reviewed. Four major study groups were defined: (A) a total of 63 cases positive for cocaine and negative for HIV (COC); (B) 40 cases positive for HIV/AIDS and negative for cocaine (HIV), (C) 23 cases both HIV/AIDS and cocaine (HIV/COC), and (D) a control group of 61 age-, sex- and race-matched, negative for cocaine and for HIV (CONT). The following morphologic and demographic data were analyzed: heart weight, left ventricular hypertrophy, myocardial fibrosis, thickening of the intramyocardial vessels, myocarditis, acute or remote myocardial infarcts (MI), age, sex, and race. Increased frequency of coronary wall and adventitial infiltrates, myocarditis, and thickened intramyocardial vessels present in HIV/COC group (14.5%, 17.4%, and 17.4% vs. 6.5%, 3.3%, and 0% in CONT group) may indicate possible combined and/or cumulative effects of HIV and cocaine on cardiovascular pathology.

Objective: The purpose of this study was to determine levels of intrauterine infection and transcriptional activity in cord blood mononuclear cells that were collected at term from fetuses who were born to women who were infected with human immunodeficiency virus (HIV) and who received highly active antiretroviral therapy (HAART)., Study Design: RNA and DNA were isolated from maternal placental tissues and fetal cord blood specimens that were obtained at term from pregnant women who were infected with HIV and who received HAART. Levels of integrated HIV provirus and messenger RNA transcripts were determined by real-time polymerase chain reaction., Results: Detectable levels of transcriptionally active integrated provirus were present in approximately 27% of cord blood samples (n = 22) that were collected from fetuses who born to HIV-positive mothers who received HAART. Levels of HIV-p24 antigen in cultures that were detected in randomly selected cord blood samples confirmed the presence of inducible infectious virus., Conclusion: These findings suggest that some fetuses from HIV-infected mothers who receive HAART and who may be HIV-negative infants after delivery can harbor circulating leukocytes that are infected productively by intrauterine transmission of HIV.

We have proposed that, unlike other HIV-vulnerable cell lineages, progenitor mast cells (prMCs), cultured in vitro from undifferentiated bone marrow-derived CD34(+) pluripotent progenitors (PPPs), are susceptible to infection during a limited period of their ontogeny. As infected prMCs mature in culture, they lose expression of viral chemokine coreceptors necessary for viral entry and develop into long-lived, latently infected mature tissue mast cells (MCs), resistant to new infection. In vivo recruitment of prMCs to different tissue compartments occurs in response to tissue injury, growth, and remodeling or allergic inflammation, allowing populations of circulating and potentially HIV-susceptible prMCs to spread persistent infection to diverse tissue compartments. In this report, we provide in vivo evidence to confirm this model by demonstrating that HIV-infected women have both circulating prMCs and placental tissue MCs (PLMCs) that harbor inducible infectious HIV even after highly active antiretroviral therapy (HAART) during pregnancy. Furthermore, infectious virus, capable of infecting alloactivated fetal cord blood mononuclear cells (CBMCs), could be induced in isolated latently infected PLMCs after weeks in culture in vitro. These data provide the first in vivo evidence that tissue MCs, developed from infected circulating prMCs, comprise a long-lived inducible reservoir of persistent HIV in infected persons during HAART.

The loss of CD4(+) T cells and the impairment of CD8(+) T cell function in HIV infection suggest that pharmacological treatment with IL-7 and IL-15, cytokines that increase the homeostatic proliferation of T cells and improve effector function, may be beneficial. However, these cytokines could also have a detrimental effect in HIV-1-infected individuals, because both cytokines increase HIV replication in vitro. We assessed the impact of IL-7 and IL-15 treatment on viral replication and the immunogenicity of live poxvirus vaccines in SIV(mac251)-infected macaques (Macaca mulatta). Neither cytokine augmented the frequency of vaccine-expanded CD4(+) or CD8(+) memory T cells, clonal recruitment to the SIV-specific CD8(+) T cell pool, or CD8(+) T cell function. Vaccination alone transiently decreased the viral set point following antiretroviral therapy suspension. IL-15 induced massive proliferation of CD4(+) effector T cells and abrogated the ability of vaccination to decrease set point viremia. In contrast, IL-7 neither augmented nor decreased the vaccine effect and was associated with a decrease in TGF-beta expression. These results underscore the importance of testing immunomodulatory approaches in vivo to assess potential risks and benefits for HIV-1-infected individuals.

The monitoring of the efficacy of anti-retroviral therapy (ART) is becoming an important issue in the developing world. The current use of CD4 counts, plasma viral loads, and monitoring of drug-resistant viruses are at present either uninformative or costly. Thus, more new cost-effective and practical techniques need to be established and implemented. Towards this goal, our lab has carried out studies on the potential use of CD38 frequency and density expression by flow analysis as a means to assess the efficacy of ART. Results of our studies using whole blood sample from normal healthy donors indicate that CD38 is expressed by a high frequency of not only CD4+ and CD8+ T cells but also most hematopoietic cell lineages analyzed. Detailed studies of CD38 expression along with other cell surface markers using whole blood sample from HIV-1-infected patients showed that the most discriminating change was the increased frequency and density of CD38 expression by CD3+CD8+ T cells. Of importance was our preliminary finding that a reversal of the increased frequency and density of CD38 expression by CD8+ T cells only appeared in the whole blood sample from patients who were responders to ART but not those who were drug failures. These initial data provide a platform and incentive for larger cohort studies including prospective pre- and post-ART for the institution of such monitoring techniques in resource limited settings.

The goal of this communication is to summarize the following-the types of autoimmune responses that have been characterized in human HIV-1 infection; the potential mechanisms that were initially thought to be the basis for such autoimmune responses; the prevalence and incidence of conventional autoimmune diseases with HIV-1 infection; the spectrum of autoimmune disorders following the institution of HAART and its associated mechanisms; the role of such autoimmunity in SIV-infected nonhuman primates; and the molecular basis for autoimmune responses, such as the role of exosomes in lentiviral disease.

Studies on PBMC samples from HIV-1 infected patients have shown that despite substantial number of HIV specific CTLs, these patients gradually progress to AIDS. The present study was conducted to determine whether this paradox was secondary to the influence of protease inhibitors being utilized by these patients. Thus, aliquots of PBMC samples from 10 HIV infected humans with no prior history of anti-retroviral drug therapy (ART) and 6 HIV-infected patients that had been on HAART for > 1 year were analyzed for the frequency of HIV-1 Nef and Gag dominant peptide specific tetramer+ cells, respectively. The tetramer+ PBMCs were analyzed for their ability to synthesize specific peptide induced IFN-gamma utilizing both the ELISPOT and the intracellular cytokine (ICC) assays. Results of the studies showed that there was an overall correlation between the frequency of Nef and Gag peptide tetramer+ cells and the frequency of IFN-gamma synthesizing cells as assayed by either ICC or ELISPOT assay, markedly reduced values of IFN-gamma synthesizing cells per unit tetramer+ cells were noted in both group of patients. These data suggest that the frequency of HIV-specific CD8+ T cells is maintained during the chronic phase of infection, their ability to function is compromised and is not a reflection of ART. While the addition of IL-2, anti-CD40L and allogeneic cells led to partial increase in the ability of the tetramer+ cells to synthesize IFN-gamma, the addition of IL-4, IL-12, anti-CD28 or a cocktail of antiTGF-beta, TNF-alpha and IL-10 failed to augment the IFN-gamma response.

Treating macaques with an anti-α4β7 antibody under the umbrella of combination antiretroviral therapy (cART) during early SIV infection can lead to viral remission, with viral loads maintained at < 50 SIV RNA copies/ml after removal of all treatment in a subset of animals. Depletion of CD8+ lymphocytes in controllers resulted in transient recrudescence of viremia, suggesting that the combination of cART and anti-α4β7 antibody treatment led to a state where ongoing immune responses kept the virus undetectable in the absence of treatment. A previous mathematical model of HIV infection and cART incorporates immune effector cell responses and exhibits the property of two different viral load set-points. While the lower set-point could correspond to the attainment of long-term viral remission, attaining the higher set-point may be the result of viral rebound. Here we expand that model to include possible mechanisms of action of an anti-α4β7 antibody operating in these treated animals. We show that the model can fit the longitudinal viral load data from both IgG control and anti-α4β7 antibody treated macaques, suggesting explanations for the viral control associated with cART and an anti-α4β7 antibody treatment. This effective perturbation to the virus-host interaction can also explain observations in other nonhuman primate experiments in which cART and immunotherapy have led to post-treatment control or resetting of the viral load set-point. Interestingly, because the viral kinetics in the various treated animals differed—some animals exhibited large fluctuations in viral load after cART cessation—the model suggests that anti-α4β7 treatment could act by different primary mechanisms in different animals and still lead to post-treatment viral control. This outcome is nonetheless in accordance with a model with two stable viral load set-points, in which therapy can perturb the system from one set-point to a lower one through different biological mechanisms. Author summary: Some macaques treated with an anti-α4β7 monoclonal antibody along with antiretroviral therapy during the early stages of simian immunodeficiency virus infection had their viral load become undetectable (below 50 SIV RNA copies/ml) after all treatment was stopped, whereas animals not given the antibody all had their viral loads rebound to high levels. Using a mathematical model, we examined four potential ways in which the antibody could have altered the balance between viral growth and immune control to maintain an undetectable viral load. We show that a shift to controlled infection can occur through multiple biologically reasonable mechanisms of action of the anti-α4β7 antibody. [ABSTRACT FROM AUTHOR]

The purpose of this review is to provide an overview of the spectrum of autoimmune responses that we have so far characterized in the simian immunodeficiency virus (SIV)-infected disease susceptible rhesus macaques, the potential role of the lymphopenic state for the generation of the autoimmune response and the important new finding that such autoimmune response in fact can serve to provide both clinical benefit and clinical disease depending on the stage of the disease and the nature of the host proteins that are recognized during this process. [ABSTRACT FROM AUTHOR]

Background Our lab has previously shown that adoptive transfer of in vitro expanded autologous purified polyclonal CD4+ T cells using anti-CD3/CD28 coated beads induced antiviral responses capable of controlling simian immunodeficiency virus (SIV) replication in vivo. Results Expansion on anti-CD3/28 coated beads was found to induce a true polyclonal expansion as CFSE labeled cells uniformly showed dilution of the dye over several days of culture, in contrast to aliquots of the same cells subjected to mitogen stimulation. Of interest was the finding that CD4+ T cells collected before and during early chronic SIV infection or AIDS stage did not show any or only modest differences in proliferative response or expansion kinetics. The reason for such excellent expansion properties was analyzed by the quantitation of telomerase activity in aliquots of expanding CD4+ T cells from sample collected at various times post-infection. First, anti-CD3/28 expanded CD4+ T cells exhibited telomerase levels 2- to 20-fold higher than the starting population of CD4+ T cells. Moreover, while telomerase activity in ex vivo tested CD4+ T cells was found to decrease following SIV infection and disease progression, anti-CD3/28 expansion appeared to restore significant levels of telomerase activity as no difference was noted in telomerase expression between CD4+ T cells expanded from samples collected before or during the chronic SIV infection. When such expanded and CFSE labeled T cells were autologously transferred to monkeys, evidence for extended survival in vivo was provided as CFSE labeled cells were detected to relatively high levels in blood and spleen at 1 week post-infection. Conclusion In summary, the data suggest that anti-CD3/28 mediated expansion of CD4+ T cells retains its immunotherapeutic potential not only during the early stages of lentiviral infection but also at more advanced stages of disease. [ABSTRACT FROM AUTHOR]

We have previously reported that immunization of the severe combined immunodeficiency (SCID) mice reconstituted with human peripheral blood mononuclear cells (PBMC) (hu-PBL-SCID mice) with inactivated human immunodeficiency virus type-1 (HIV-1)-pulsed-autologous dendritic cells (HIV-DC) elicits HIV-1-reactive CD4 + T cells that produce an as yet to be defined novel soluble factor in vitro with anti-viral properties against CCR5 tropic (R5) HIV-1 infection. These findings led us to perform studies designed to identify the lineage of the cell that synthesizes such a factor in vivo and define the epitopes of HIV-1 protein that have specificity for the induction of such anti-viral factor. Results of our studies show that this property is a function of CD4 + but not CD8 + T cells. Human CD4 + T cells were thus recovered from the HIV-DC-immunized hu-PBL-SCID mice and were re-stimulated in vitro by co-culture for 2 days with autologous adherent PBMC as antigen presenting cells, APC previously pulsed with inactivated HIV in IL-2-containing medium to expand HIV-1-reactive CD4 + T cells. Aliquots of these re-stimulated CD4 + T cells were then co-cultured with similar APC's that were previously pulsed with 10 μg/ml of a panel of HIV peptides for an additional 2 days, and their culture supernatants were examined for the production of both the R5 HIV-1 suppression factor and IFN-γ. The data presented herein show that the HIV-1 primed CD4 + T cells produced the R5 suppression factor in response to a wide variety of HIV-1 gag, env, pol, nef or vif peptides, depending on the donor of the CD4 + T cells. Simultaneous production of human interferon (IFN)-γ was observed in some cases. These results indicate that human CD4 + T cells in PBMC of HIV-1 naive donors have a wide variety of HIV-1 epitope-specific CD4 + T cell precursors that are capable of producing the R5 HIV-1 suppression factor upon DC-based vaccination with whole inactivated HIV-1. [ABSTRACT FROM AUTHOR]

Abstract: Autoimmune antibodies and autoimmune responses have been characterized in both human HIV infection and the rhesus macaque (RM) non-human primate model of SIV infection and reasoned to contribute to the pathogenesis of AIDS. Many theories for the induction and maintenance of such responses have been entertained including molecular mimicry between HIV proteins and self molecules, CD4+ T cell loss accompanied by loss of normal immune regulation that dictate self–non-self-reactivity, defective negative/positive selection of T cells to name a few. The precise mechanisms that lead to such immune dysfunction is difficult to study in humans. Our lab has been studying such autoimmune responses in both SIV-infected RM and sooty mangabeys (SM), a species from Africa that are naturally infected with SIV but do not display any detectable signs of immune deficiency or autoimmunity. We submit that this model is an important model since it allows for narrowing down those mechanisms and pathways that are a result of lentiviral infection per se from those that specifically cause disease including autoimmunity. During the course of these studies, we have ruled out a role for plasma and cellular viral loads, anti-viral humoral responses and a variety of cell signaling pathways. We have identified select pathways that appear to play roles in the pathogenesis of lentiviral infection and disease. These include pathways involved in innocent bystander killing by apoptosis of CD4+ T cells, role for differential regulation of the cell cycle, and a role for distinct host proteins that get incorporated by the virions as they are assembled and either bud out of CD4+ T cells or exit the cells in the form of multi-vesicular endosomal particles from monocytes/macrophages from SIV-infected disease susceptible RM and disease-resistant SM. We present our current working model and hypotheses that are designed to elucidate differences that are responsible for such distinct outcomes of lentiviral infection, autoimmunity and disease. We believe that such findings have important implications for the design of vaccines against human HIV infection. [Copyright &y& Elsevier]

The shift from a predominant synthesis of prototype Th1 cytokines to Th2 or Th0 type of cytokines by antigen activated PBMC's from HIV infected humans and SIV infected disease susceptible rhesus macaques (RM) has been shown to be associated with disease progression. Paradoxically, antigen activated PBMC's from sooty mangabeys (SM), which are naturally infected with SIV and are disease resistant despite high viral loads, maintain a predominant Th2 cytokine profile. It has been reasoned that the resistance to perturbations of cytokine synthesis by slow and/or nonprogressor HIV infected patients and SIV infected disease susceptible RM is secondary to inherited polymorphisms within the promoter regions for cytokines. Similar promoter polymorphisms could also contribute to the cytokine profile of PBMC's from SM. To address this issue promoter regions for the major Th1/Th2 cytokines from RM and SM were cloned and sequenced. Sequence analysis of promoter fragments of IL-4, IL-10, IL-12 p40, IFN-gamma and TNF-alpha from the two monkey species showed varying degree of homology ranging from high degree of homology detected for IFN-gamma promoter (>99%) to relatively high degree of polymorphism detected for TNF-alpha promoter (94% homology). In addition, several variable regions within the promoters of IL-12 p40, IL-10 and TNF-alpha in the two species contain polymorphisms in sequences that constitute binding sites of known transcription factors (TF). Such differences are likely to differentially bind TF and thus either qualitatively and/or quantitatively affect the regulation of cytokine synthesis in these two species and potentially contribute to disease progression and/or resistance. [ABSTRACT FROM AUTHOR]

CD4+ T cells play a central role in the immunopathogenesis of HIV/AIDS, and their depletion during chronic HIV infection is a hallmark of disease progression. However, the relative contribution of CD4+ T cells as mediators of antiviral immune responses and targets for virus replication is still unclear. Here, we have generated data in SIV-infected rhesus macaques (RMs) that suggest that CD4+ T cells are essential in establishing control of virus replication during acute infection. To directly assess the role of CD4+ T cells during primary SIV infection, we in vivo depleted these cells from RMs prior to infecting the primates with a pathogenic strain of SIV. Compared with undepleted animals, CD4+ lymphocyte-depleted RMs showed a similar peak of viremia, but did not manifest any post-peak decline of virus replication despite CD8+ T cell- and B cell-mediated SIV-specific immune responses comparable to those observed in control animals. Interestingly, depleted animals displayed rapid disease progression, which was associated with increased virus replication in non-T cells as well as the emergence of CD4-independent SIV-envelopes. Our results suggest that the antiviral CD4+ T cell response may play an important role in limiting SIV replication, which has implications for the design of HIV vaccines. [ABSTRACT FROM AUTHOR]

Summary: Interaction between OX40 expressed on activated T cells and its ligand (OX40L) on antigen presenting cells (APC) provides a co-stimulatory signal for T cells to promote acquired immunity. In the present study, we have examined various culture conditions for optimum OX40L expression on T cells stimulated with immobilized anti-CD3/CD28 monoclonal antibodies (mAbs). Although the day 3 primed T cells expressed minimal OX40L, after repeated stimulations both the CD4+ and CD8+ T cells became OX40L positive as determined by flow cytometry. Interleukin (IL)–12 interfered with the OX40L expression. Among activated T cells, a higher frequency of CD8+ T cells expressed OX40L than CD4+ T cells. By blocking OX40L-OX40 interaction by an anti-OX40 mAb, the number of OX40L+ T cells significantly increased. Screening of various cytokines showed that transforming growth factor (TGF)–β1 was capable of induction of OX40L on the activated T cells within 3 days. The OX40L expressed on T cells was functional, as they bound soluble OX40 and stimulated human immunodeficiency virus–1 (HIV-1) production from cell lines chronically infected with HIV-1 and expressing OX40. Altogether the present study findings indicate that functional OX40L is inducible on human activated CD4+ and CD8+ T cells, and that the expression is enhanced by TGF-β1. [Copyright &y& Elsevier]

CD4[sup +] T-cell dysfunction highlighted by defects within the intracellular signaling cascade and cell cycle has long been characterized as a direct and/or indirect consequence of human immunodeficiency virus (HIV) infection in humans and simian immunodeficiency virus (SIV) infection in rhesus macaques (RM). Dysregulation of the M phase of the cell cycle is a well-documented effect of HIV or SIV infection both in vivo and in vitro. In this study the effect of SIV infection on the modulation of two important regulators of the M phase—polo-like kinases Plk3 and Plk1—was investigated. We have previously shown that PIk3 is markedly downregulated in CD4[sup +] T cells from SIV-infected disease-susceptible RM but not SIV-infected diseaseresistant sooty mangabeys (SM), denoting an association of downregulation with disease progression. Here we show that, in addition to the downregulation, Plk3 exhibits aberrant activation patterns in the CD4[sup +] T cells from SIV-infected RM following T-cell receptor stimulation. Interestingly, in vitro SIV infection of CD4[sup +] T cells leads to the upregulation, rather than downregulation, of Plk3, suggesting that different mechanisms operate in vitro and in vivo. In addition, CD4[sup +] T cells from RM with high viral loads exhibited consistent and significant upregulation of Plk1, concurrent with an aberrant activation-induced Plk1 response, suggesting complex mechanisms of SIV-induced M-phase abnormalities in vivo. Altogether this study presents a novel mechanism underlying M-phase defects observed in CD4[sup +] T cells from HIV or SIV-infected disease-susceptible humans and RM which may contribute to aberrant T-cell responses and disease pathogenesis. [ABSTRACT FROM AUTHOR]