Lena Al-Harthi

Maximum suppression of Hiv replication leads to the restoration of Hiv-specific responses in early Hiv disease

ObjectivesIt is predicted that HIV-infected individuals in early HIV disease are the most likely group to achieve immune reconstitution following highly active antiretroviral treatment. We assessed whether suppression of HIV replication in this group would improve immune function. MethodsSeventeen antiretroviral-naïve patients in early HIV disease were evaluated for immune function and lymphocyte phenotyping using standard immunological assays. ResultsAbsolute CD4+ T-cell number increased from a median of 550 to 800 × 106 cells/l while CD8+ T-cell numbers were reduced. The decrease in CD8+ cells correlated with a decrease in the CD8+ memory phenotype. Kinetics of CD4+ naïve and memory T-cell rise indicated that 80% of the maximum CD4+ naïve increase was achieved within 18 weeks whereas maximum CD4+ memory T-cell rise was achieved within 36 weeks. Activation markers (HLA-DR, CD38) and an apoptosis-related marker (CD95) were reduced on CD4+ and CD8+ T cells. Lymphocyte proliferation responses to tetanus toxoid, alloantigen, and anti-CD3/CD28 were restored in patients that were initially unresponsive. At baseline, 31% of the patients responded to HIV p24, which increased to 69% post-therapy. The inducible RANTES response was normalized following therapy whereas inducible interferon-γ, interleukin (IL)-12, and MIP1β were elevated. The depressed inducible IL-10 response, however, was not altered after therapy. ConclusionsThis is one of the first studies to demonstrate the restoration of HIV-1 specific responses in non-acute HIV infection, suggesting early intervention with potent antiretroviral therapy may reverse immune-mediated damage not seen with treated patients who have more advanced disease.

Upregulation of CD4 on CD8+ T cells: CD4dimCD8bright T cells constitute an activated phenotype of CD8+ T cells

Aside from an intermediate stage in thymic T‐cell development, the expression of CD4 and CD8 is generally thought to be mutually exclusive, associated with helper or cytotoxic T‐cell functions, respectively. Stimulation of CD8+ T cells, however, induces the de novo expression of CD4. We demonstrate that while superantigen (staphylococcal enterotoxin B, SEB) and anti‐CD3/CD28 costimulation of purified CD8+ T cells induced the expression of CD4 on CD8+ T cells by 30 and 17%, respectively, phytohaemagglutinin (PHA) stimulation did not induce CD4 expression on purified CD8+ T cells but significantly induced the expression of both CD4 on CD8 (CD4dimCD8bright) and CD8 on CD4 (CD4brightCD8dim) T cells in unfractionated peripheral blood mononuclear cells (PBMC). The level of the PHA‐mediated induction of CD4dimCD8bright and CD4brightCD8dim was at 27 and 17%, respectively. Depletion of CD4+ T cells from PBMC abrogated this PHA‐mediated effect. Autologous CD4+ and CD8+ T‐cell co‐cultures in the presence of PHA induced this CD4dimCD8bright T‐cell expression by 33%, demonstrating a role for CD4 cells in the PHA‐mediated induction of the double positive cells. The induction of CD4dimCD8bright was independent of a soluble factor(s). Phenotypic analysis of CD4dimCD8bright T cells indicated significantly higher levels of CD95, CD25, CD38, CD69, CD28, and CD45RO expression than their CD8+CD4− counterparts. CD4dimCD8bright T cells were also negative for CD1a expression and were predominately T‐cell receptor (TCR) αβ cells. Our data demonstrate that CD4dimCD8bright T cells are an activated phenotype of CD8+ T cells and suggest that CD4 upregulation on CD8+ T cells may function as an additional marker to identify activated CD8+ T cells.

Detection of T cell receptor circles (TRECs) as biomarkers for de novo T cell synthesis using a quantitative polymerase chain reaction–enzyme linked immunosorbent assay (PCR–ELISA)

Currently, phenotypic markers that distinguish between recent thymic emigrants/de novo T cells and the rest of the peripheral T cell pool are lacking. This distinction is critical in studies aimed at evaluating immune reconstitution following intensive chemotherapy, in immunodeficiency-related therapies, or in the elucidation of the kinetics of thymic function. During V(D)J T cell receptor rearrangement, DNA extrachromosomal excision products are generated. These products, known as T cell receptor excision circles (TRECs), are not replicated during mitosis and are thus diluted with each round of cell division. Therefore, TRECs can be used as an indicator of recent thymic emigrants. Thus far, quantitative competitive-polymerase chain reaction (QC-PCR) and real time PCR were used to measure TREC levels. However, QC-PCR relies on radioactivity, is cumbersome when processing many samples at once and the cost of real time PCR does not make it a viable option for many laboratories. We describe here the development of a quantitative PCR-ELISA method for the measurement of coding joint TRECs generated from ValphaJalpha recombination. Our assay is ultra sensitive, relies on biotin labeling rather than radioactivity, is based on a 96-well format making multiple process sampling relatively easy, and is cost effective. Using this PCR-ELISA method, we evaluated thymic output among 22 normal subjects, ranging in age from 22-53 years, and among HIV-infected individuals following highly active antiretroviral therapy (HAART). We demonstrate that an inverse relationship exists between TREC levels and aging in normal individuals and that, among some HIV patients, HAART treatment leads to enhanced thymic output. Our assay has direct relevance in projects examining normal and abnormal thymic function and in immune reconstitution studies.

Bacterial vaginosis-associated microflora isolated from the female genital tract activates HIV-1 expression.

Alteration of cervicovaginal microbial flora can lead to vaginosis, which is associated with an increased risk of HIV-1 transmission. We recently characterized a soluble HIV-inducing factor (HIF) from the cervicovaginal lavage (CVL) samples of women. The goals of this study were to determine the effect of cervicovaginal microflora on HIV-1 expression and to elucidate the relationship between HIF activity and microflora. Physiologically relevant microorganisms, Mycoplasma, diphtheroid-like bacteria, Gardnerella vaginalis, Streptococcus agalactiae, and Streptococcus constellatus, cultured from the CVL of a representative woman with a clinical condition of bacterial vaginosis and possessing HIF activity, induced HIV-1 expression. The magnitude of virus induction varied widely with the greatest stimulation induced by diphtheroid-like bacteria and Mycoplasma. The transcriptional induction by Mycoplasma was mediated by activation of the KB enhancer, an activation mechanism shared with HIF. Also as with HIF, Mycoplasma induced AP-1 dependent transcription. Polymerase chain reaction (PCR)-based speciation showed that the isolate was M. hominis. Our data indicate that bacterial vaginosis-associated microflora can enhance HIV-1 transcription and replication and identify M. hominis as a potential source for HIF activity. The virus-enhancing activities associated with the microflora and HIF may increase genital tract viral load, potentially contributing to HIV transmission.

CD8+ T Cell Activation in Women Coinfected with Human Immunodeficiency Virus Type 1 and Hepatitis C Virus

Immune activation is a hallmark of human immunodeficiency virus type 1 (HIV-1) infection and impacts innate and adaptive immunity. Individuals coinfected with HIV-1 and hepatitis C virus (HCV) may have increased immune activation early in HIV disease because of a high HCV antigen load in tissues such as the liver. We evaluated T cell markers of activation and maturation in women with or without HIV-1 infection, by HCV antibody and HCV RNA status. We found increased percentages of activated CD8(+) T cells (i.e., CD8(+)HLA-DR(+)38(+) cells and CD8(+)CD28(+)HLA-DR(+) cells) but not of CD4(+) T cells among women who tested positive for HIV-1, HCV antibody, and HCV RNA, compared with HIV-1-positive women who tested negative for HCV antibody. Because CD8(+) T cell activation is related to HIV-1 disease progression, these data may have implications for the medical management of patients coinfected with HIV-1 and HCV.

The impact of the ovulatory cycle on cytokine production: evaluation of systemic, cervicovaginal, and salivary compartments.

To understand the impact of the menstrual cycle on immunologic parameters, we measured the level of cytokines and chemokines from plasma, cervicovaginal lavage (CVL), and saliva samples of 6 premenopausal women during the follicular and luteal phases of the ovulatory cycle. We demonstrate that the level of plasma interleukin-8 (IL-8) was 4-fold higher during the follicular phase than the luteal phase (p = 0.004), whereas plasma IL-1beta, IL-4, IL-6, IL-10, interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1alpha (MIP-1alpha), and TNF receptor II (TNFR II) were not altered during the ovulatory cycle. In the vaginal compartment, as measured from CVL samples, the levels of IL-6 and IL-1beta were both 5-fold higher in the follicular than the luteal phase (p = 0.0002 and 0.03, respectively). Salivary cytokine and chemokine samples were similar when measured during the luteal and the follicular phases. Additional analysis of lymphocyte subsets for phenotypic and functional markers indicated that they were not influenced by the ovulatory cycle. Collectively, these data suggest that IL-6, IL-8, and IL-1beta are differentially regulated during the ovulatory cycle.

Activation of Plasmacytoid Dendritic Cells with TLR9 Agonists Initiates Invariant NKT Cell-Mediated Cross-Talk with Myeloid Dendritic Cells

CD1d-restricted invariant NK T (iNKT) cells and dendritic cells (DCs) have been shown to play crucial roles in various types of immune responses, including TLR9-dependent antiviral responses initiated by plasmacytoid DCs (pDCs). However, the mechanism by which this occurs is enigmatic because TLRs are absent in iNKT cells and human pDCs do not express CD1d. To explore this process, pDCs were activated with CpG oligodeoxyribonucleotides, which stimulated the secretion of several cytokines such as type I and TNF-α. These cytokines and other soluble factors potently induced the expression of activation markers on iNKT cells, selectively enhanced double-negative iNKT cell survival, but did not induce their expansion or production of cytokines. Notably, pDC-derived factors licensed iNKT cells to respond to myeloid DCs: an important downstream cellular target of iNKT cell effector function and a critical contributor to the initiation of adaptive immune responses. This interaction supports the notion that iNKT cells can mediate cross-talk between DC subsets known to express mutually exclusive TLR and cytokine profiles.

Activation of CD8 T Cells Predicts Progression of HIV Infection in Women Coinfected with Hepatitis C Virus

BACKGROUND Because activation of T cells is associated with human immunodeficiency virus (HIV) pathogenesis, CD4 and CD8 activation levels in patients coinfected with HIV and hepatitis C virus (HCV) may explain conflicting reports regarding effects of HCV on HIV disease progression. METHODS Kaplan-Meier and multivariate Cox regression models were used to study the risk of incident clinical AIDS and AIDS-related deaths among 813 HCV-negative women with HIV infection, 87 HCV-positive nonviremic women with HIV coinfection, and 407 HCV-positive viremic women with HIV coinfection (median follow-up time, 5.2 years). For 592 women, the percentages of activated CD4 and CD8 T cells expressing HLA-DR (DR) and/or CD38 were evaluated. RESULTS HCV-positive viremic women had a statistically significantly higher percentage of activated CD8 T cells (P < .001) and a statistically significantly higher incidence of AIDS compared with HCV-negative women (P < .001 [log-rank test]). The AIDS risk was greater among HCV-positive viremic women in the highest tertile compared with the lowest tertile (>43% vs <26%) of CD8(+)CD38(+)DR(+) T cells (hazard ratio, 2.94 [95% confidence interval, 1.50-5.77]; P = .001). This difference was not observed in the HCV-negative women (hazard ratio, 1.87 [95% confidence interval, 0.80-4.35]; P = .16). In contrast, CD4 activation predicted AIDS in both groups similarly. Increased percentages of CD8(+)CD38(-)DR(+), CD4(+)CD38(-)DR(-), and CD8(+)CD38(-)DR(-) T cells were associated with a >60% decreased risk of AIDS for HCV-positive viremic women and HCV-negative women. CONCLUSION HCV-positive viremic women with HIV coinfection who have high levels of T cell activation may have increased risk of AIDS. Earlier treatment of HIV and HCV infection may be beneficial.

Negative-Strand Hepatitis C Virus (HCV) RNA in Peripheral Blood Mononuclear Cells from Anti-HCV–Positive/HIV-Infected Women

BACKGROUND Hepatitis C virus (HCV) has been reported to replicate in peripheral blood mononuclear cells (PBMCs), particularly in patients coinfected with HCV and human immunodeficiency virus (HIV). However, there are limited data regarding the prevalence of and the factors associated with extrahepatic replication. METHODS The presence of negative-strand HCV RNA in PBMCs was evaluated by a strand-specific assay for 144 anti-HCV-positive/HIV-infected women enrolled in the Womens Interagency HIV Study. One to 5 PBMC samples obtained from each woman were tested. Multivariate analyses were used to assess for associations with the clinical and demographic characteristics of the women. RESULTS Negative-strand HCV RNA was detected in 78 (25%) of 315 specimens, and, for 61 women (42%), > or = 1 specimen was found to have positive results. The presence of negative-strand HCV RNA in PBMCs was significantly positively associated with an HCV RNA plasma level of > or = 6.75 log copies/mL (P=.04) and consumption of > or = 7 alcoholic drinks per week (P=.02). It was also negatively associated with injection drug use occurring in the past 6 months (P=.03). A negative association with a CD4+ CD38+ DR+ cell percentage of > 10% and a positive association with acquired immunodeficiency syndrome were borderline significant (P=.05). CONCLUSIONS HCV replication in PBMCs is common among HIV-coinfected women and appears to be a dynamic process related to lifestyle, virologic, and immunologic factors.

A menstrual cycle pattern for cytokine levels exists in HIV-positive women: implication for HIV vaginal and plasma shedding.

Objectives To evaluate the effect of the menstrual cycle in HIV-positive women on plasma and genital cytokine levels, interrelationships between vaginal and plasma cytokines, CD4 and CD8 T cell fluctuations, and genital and plasma viral loads. Methods Plasma and cervicovaginal lavage specimens were collected from 55 HIV-positive women with CD4 cell counts < 350 cells/μl during phases of the menstrual cycle. Samples were assayed for IL-1β, IL-6, IL-4, IL-8, IL-10, TGFβ, TNFα, INFγ, MIP1α, MIP1β, RANTES, and TNFR-II using enzyme-linked immunosorbent assays. CD4 and CD8 T cell expression was evaluated by flow cytometry. Repeated measures regression models were used to assess the effect of the menstrual cycle on cytokines and viral load. Multivariate repeated regression models were used to assess the correlation among selected cytokines and between selected cytokines and HIV viral load. Results Vaginal IL-1β, IL-4, IL-6, IL-8, IL-10, MIP1β, RANTES, TGFβ, and TNFR-II were significantly elevated during menses but were not altered during other phases. Plasma cytokine levels were not altered during the menstrual cycle. A positive Candida culture increased vaginal IL-8 during menses, whereas vaginal discharge was associated with a reduction in vaginal IL-4, IL-10, and RANTES. CD4 and CD8 cell numbers did not vary with the menstrual cycle. Vaginal cytokine levels correlated only with vaginal viral load, in a sampling method-dependent manner. Conclusion We provide evidence of elevated vaginal cytokine levels during menses, which appear to regulate vaginal and not plasma HIV shedding, suggesting that a menstrual cycle pattern exists for cytokine production in HIV-positive women impacting vaginal shedding of HIV.