Xiao-Li Huang

Prolonged Suppression of Human Immunodeficiency Virus Type 1 (HIV-1) Viremia in Persons with Advanced Disease Results in Enhancement of CD4 T Cell Reactivity to Microbial Antigens but Not to HIV-1 Antigens

CD4 T cell responses were studied for >2 years in 27 zidovudine-experienced patients with advanced human immunodeficiency virus type 1 (HIV-1) infection who received triple combination drug therapy with indinavir, zidovudine and lamivudine or zidovudine plus lamivudine or zidovudine alone for 24-42 weeks before switching to the three-drug therapy. Subjects initially given the three drugs had viremia suppressed to undetectable levels and increases in T cell proliferative and cytokine responses to microbial antigens through 2 years of follow-up. Patients receiving the triple-drug therapy after either indinavir or zidovudine-lamivudine treatment had similar increases in T cell responses only if they also had suppression of virus load. CD4 T cell reactivity to HIV-1 antigens was not restored. Prolonged indinavir-zidovudine-lamivudine treatment has significant but incomplete enhancing effects on CD4 T cell reactivity, which could be important in host control of microbial and persistent HIV-1 infections.

Induction of Anti-Human Immunodeficiency Virus Type 1 (HIV-1) CD8+ and CD4+ T-Cell Reactivity by Dendritic Cells Loaded with HIV-1 X4-Infected Apoptotic Cells

ABSTRACT T-cell responses to X4 strains of human immunodeficiency virus type 1 (HIV-1) are considered important in controlling progression of HIV-1 infection. We investigated the ability of dendritic cells (DC) and various forms of HIV-1 X4 antigen to induce anti-HIV-1 T-cell responses in autologous peripheral blood mononuclear cells from HIV-1-infected persons. Immature DC loaded with HIV-1 IIIB-infected, autologous, apoptotic CD8− cells and matured with CD40 ligand induced gamma interferon production in autologous CD8+ and CD4+ T cells. In contrast, mature DC loaded with HIV-1 IIIB-infected, necrotic cells or directly infected with cell-free HIV-1 IIIB were poorly immunogenic. Thus, HIV-1-infected cells undergoing apoptosis serve as a rich source of X4 antigen for CD8+ and CD4+ T cells by DC. This may be an important mechanism of HIV-1 immunogenicity and provides a strategy for immunotherapy of HIV-1-infected patients on combination antiretroviral therapy.

Delivery of Liposome-Encapsulated HIV Type 1 Proteins to Human Dendritic Cells for Stimulation of HIV Type 1-Specific Memory Cytotoxic T Lymphocyte Responses

An important aspect of vaccine development involves delivery of antigens to antigen-presenting cells for the induction of potent antigen-specific T lymphocyte responses. We investigated the effect of a cationic liposome, lipofectin, on delivery of whole proteins to human dendritic cells (DCs) derived from blood mononuclear cells by culture in interleukin 4 and granulocyte-monocyte colony-stimulating factor for stimulation of human immunodeficiency virus type 1 (HIV-1)-specific memory cytotoxic T lymphocyte (CTL) responses. Delivery of HIV-1 Gag, Pol, and Env proteins to DCs by lipofectin stimulated greater anti-HIV-1 memory CTL responses in cells from HIV-1-infected subjects than those induced by DCs loaded with protein alone. The CTLs were CD8+ and HLA class I restricted. Antigen presentation was enhanced by chloroquine, but blocked by brefeldin A and peptide aldehyde inhibitors of proteasomes, indicating that the classic MHC class I cytosolic pathway was used for processing and presentation of HIV-1 protein by the DCs. Stimulation of anti-HIV-1 CTLs by this safe, inexpensive, and broadly applicable approach may be used in DC-based therapies for HIV-1 infection.

Dendritic Cell Function during Chronic Hepatitis C Virus and Human Immunodeficiency Virus Type 1 Infection

ABSTRACT Hepatitis C virus (HCV) infection can persist despite HCV-specific T-cell immunity and can have a more aggressive course in persons coinfected with human immunodeficiency virus type 1 (HIV-1). Defects in antigen-presenting, myeloid dendritic cells (DCs) could underlie this T-cell dysfunction. Here we show that monocyte-derived DCs from persons with chronic HCV infection, with or without HIV-1 coinfection, being treated with combination antiretroviral therapy produced lower levels of interleukin 12 (IL-12) p70 in response to CD40 ligand (CD40L), whereas the expression of DC surface activation and costimulatory molecules was unimpaired. The deficiency in IL-12 production could be overcome by addition of gamma interferon (IFN-γ) with CD40L, resulting in very high, comparable levels of IL-12 production by DCs from HCV- and HIV-1-infected subjects. Smaller amounts of IL-12 p70 were produced by DCs treated with the immune modulators tumor necrosis factor alpha and IL-1β, with or without IFN-γ, and the amounts did not differ among the uninfected and infected subjects. Blocking of IL-10 with an anti-IL-10 monoclonal antibody in the CD40L-stimulated DC cultures from HCV-infected persons increased the level of IL-12 p70 production. The ability of DCs from HCV-infected persons to stimulate allogeneic CD4+ T cells or induce IL-2, IL-5, or IL-10 in a mixed lymphocyte reaction was not impaired. Thus, myeloid DCs derived from persons with chronic HCV infection or with both HCV and HIV-1 infections have defects in IL-12 p70 production related to IL-10 activity that can be overcome by treatment of the DCs with CD40L and IFN-γ. DCs from these infected subjects have a normal capacity to stimulate CD4+ T cells. The functional effectiveness of DCs derived from HCV-infected individuals provides a rationale for the DC-based immunotherapy of chronic HCV infection.

A Phase I study of subcutaneous recombinant interleukin-2 in patients with advanced Hiv disease while on zidovudine

ObjectiveA Phase I study of subcutaneous recombinant interleukin-2 (rlL-2). DesignSixteen patients with advanced HIV infection receiving 600–1200mg zidovudine per day were divided into three groups, which received sequentially 0.2 x106, 0.7x106 or 2x106 units/m2 per day of rlL-2 subcutaneously for 5 consecutive days. SettingFive-day admission to an academic tertiary care hospital. Patients, participantsSixteen unblinded, non-randomized volunteers. InterventionsSubcutaneous rlL-2. Main outcome measuresTolerance, toxicity, hematologic, immunologic and antiviral responses. ResultsrlL-2 was well-tolerated at the highest dosage, except in two patients who developed significant lymphopenia by the second day of rlL-2 administration, with rebound within 48 h after rlL-2 therapy. The number of eosinophils, CD4+ and CD8+ cells, and percentage of CD16+ (natural killer) cells, remained elevated above baseline for up to 10 weeks. Circulating rlL-2 receptor levels increased transiently during and immediately following rlL-2 administration. A twofold increase in natural killer cell activity against uninfected and HIV-infected targets was observed, but did not persist beyond 10 weeks following rlL-2 administration. There was a transient decrease in blastogenesis to phytohemagglutinin of patients receiving the highest dose of r-IL-2, but no significant change in viral burden. ConclusionsSubcutaneous rlL-2 in advanced HIV-infected patients on zidovudine was tolerated with side-effects similar to intravenous IL-2.

Primary Human Immunodeficiency Virus Type 1-Specific CD8+ T-Cell Responses Induced by Myeloid Dendritic Cells

ABSTRACT Induction of an antigenically broad and vigorous primary T-cell immune response by myeloid dendritic cells (DC) in blood and tissues could be important for an effective prophylactic or therapeutic vaccine to human immunodeficiency virus type 1 (HIV-1). Here we show that a primary CD8+ T-cell response can be induced by HIV-1 peptide-loaded DC derived from blood monocytes of HIV-1-negative adults and neonates (moDC) and by Langerhans cells (LC) and interstitial, dermal-intestinal DC (idDC) derived from CD34+ stem cells of neonatal cord blood. Optimal priming of single-cell gamma interferon (IFN-γ) production by CD8+ T cells required CD4+ T cells and was broadly directed to multiple regions of Gag, Env, and Nef that corresponded to known and predicted major histocompatibility complex class I epitopes. Polyfunctional CD8+ T-cell responses, defined as single-cell production of more than one cytokine (IFN-γ, interleukin 2, or tumor necrosis factor alpha), chemokine (macrophage inhibitory factor 1β), or cytotoxic degranulation marker CD107a, were primed by moDC, LC, and idDC to HIV-1 Gag and reverse transcriptase epitopes, as well as to Epstein-Barr virus and influenza A virus epitopes. Thus, three major types of blood and tissue myeloid DC targeted by HIV-1, i.e., moDC, LC, and idDC, can prime multispecific, polyfunctional CD8+ T-cell responses to HIV-1 and other viral antigens.

Maturation of dendritic cells for enhanced activation of anti‐HIV‐1 CD8+ T cell immunity

Maturation of dendritic cells (DC) to enhance their capacity to activate T cell immunity to HIV‐1 is a key step in immunotherapy of HIV‐1 infection with DC. We compared maturation of DC derived from HIV‐1‐uninfected subjects and infected subjects on antiretroviral therapy (ART) or ART naïve by CD40 ligand (CD40L) and combinations of TLR3 ligand polyinosinic:polycytidylic acid [poly(I:C)] and inflammatory cytokines IFN‐γ, IFN‐α, IL‐1β, and TNF‐α. The greatest levels of virus‐specific IFN‐γ production by CD8+ T cells were stimulated by DC treated with CD40L, followed by DC treated with the poly(I:C)‐cytokine combination. The highest levels of IL‐12p70 were produced by DC treated with CD40L + IFN‐γ, followed by CD40L and the poly(I:C)‐cytokine combination. Neutralization of IL‐12p70 indicated that it was only partially involved in direct enhancement of antiviral CD8+ T cell activity. DC stimulation of antiviral CD8+ T cell reactivity was enhanced by activated CD4+ T cells at low concentrations but was suppressed at higher CD4+ T cell concentrations. Maturation of DC with CD40L obviated the need for CD4+ T cell help and overcame this suppressive activity. Finally, we showed that DC from HIV‐1‐infected subjects on ART, which were treated with the poly(I:C)‐cytokine combination, retained the capacity to produce IL‐12p70 and activate anti‐HIV‐1 CD8+ T cell responses after restimulation with CD40L, with or without IFN‐γ. Thus, DC from HIV‐1‐infected subjects can be engineered with CD40L or a poly(I:C)‐cytokine combination for enhancing CD8+ T cell responses to HIV‐1, which has potential applications in HIV‐1 immunotherapy.

CD8+ T-Cell Gamma Interferon Production Specific for Human Immunodeficiency Virus Type 1 (HIV-1) in HIV-1-Infected Subjects

ABSTRACT The CD8+-T-cell response to human immunodeficiency virus type 1 (HIV-1) is considered to be important in host control of infection and prevention of AIDS. We have developed a single-cell enzyme immunoassay (enzyme-linked immunospot assay) specific for gamma interferon (IFN-γ) production stimulated by either autologous B-lymphoblastoid cell lines (B-LCL) infected with vaccinia virus vectors expressing HIV-1 proteins or synthetic peptides representing known HIV-1 CD8+ cytotoxic T-lymphocyte (CTL) epitopes. Single-cell IFN-γ production stimulated by HIV-1 Gag-, Pol-, and Env-expressing B-LCL was a reliable measure of HIV-1-specific T-cell immunity in peripheral blood CD8+ T cells from HIV-1 infected individuals. This method was more sensitive than stimulation of IFN-γ by direct infection of the cultures with HIV-1–vaccinia virus vectors. Comparable results were found for IFN-γ production in CD8+ T cells from HIV-1-negative, cytomegalovirus (CMV)-seropositive, healthy donors stimulated with B-LCL expressing the CMV pp65 lower matrix protein. HIV-1 peptides were immunodominant for both CD8+ single-cell IFN-γ production and CTL precursor frequencies. The number of cells producing IFN-γ decreased in individuals with late-stage HIV-1 infection and was temporally enhanced during combination antiretroviral therapy with two reverse transcriptase nucleoside inhibitors and a protease inhibitor.

Multiple T-Cell Responses to Human Immunodeficiency Virus Type 1 Are Enhanced by Dendritic Cells

ABSTRACT Human immunodeficiency virus type 1 (HIV-1)-specific T-cell reactivity has been related to protection from disease progression. Optimal T-cell reactivity to HIV-1 presumably requires antigen processing and presentation by professional antigen-presenting cells, particularly dendritic cells (DC). Here we examined whether multiple HIV-1-specific T-cell functions are enhanced by stimulation with HIV-1 peptide-loaded DC derived from HIV-1-infected subjects on antiretroviral therapy. We first found that mature DC increased the number of gamma interferon (IFN-γ)-producing T cells detected by enzyme-linked immunospot assay to overlapping 15-mer peptides of HIV-1 Gag and Nef, compared to stimulation with peptide-loaded, immature DC or to peptides without DC. IFN-γ production was lower in response to large pools of the Gag and Nef peptides, regardless of presentation by DC. We further observed that HIV-1 peptide-loaded, mature DC stimulated greater CD8+ and CD4+ T-cell proliferation than did the peptides without DC and that T-cell proliferation was lower in response to larger pools of the peptides. The lower T-cell IFN-γ and proliferation responses to the larger peptide pools were related to lower T-cell viability. Finally, the number of polyfunctional CD8+ and CD4+ T cells stimulated by HIV-1 peptide-loaded, mature DC, defined as positive by intracellular staining for more than one immune mediator (IFN-γ, interleukin 2, tumor necrosis factor alpha, macrophage inhibitory protein 1β, or CD107a), was greater than that stimulated by the peptides alone. These results indicate that DC can enhance multiple types of HIV-1-specific T-cell functions.

Stimulation of Anti-HIV-1 Cytotoxic T Lymphocytes by Dendritic Cells.

Dendritic cells (DC) are highly specialized antigen-presenting cells (APC) in both primary and secondary T-cell responses. This may be related to their expression of high levels of MHC class I and II antigens (1-4), costimulatory molecules CD40, CD80, and CD86 (5,6), and production of cytokines such as interleukin-12 (IL-12) (7-9), IL-6 (10), and interferon α (IFN-α) (10,11). Moreover, DC can process antigens in various forms by different pathways and induce high levels of both CD4(+)and CD8(+)T-cell reactivity (12).