Influence of interleukin-15 on CD8+ natural killer cells in human immunodeficiency virus type 1-infected chimpanzees

Practical NK cell phenotyping and variability in healthy adults

Human natural killer (NK) cells display a wide array of surface and intracellular markers that indicate various states of differentiation and/or levels of effector function. These NK cell subsets exist simultaneously in peripheral blood and may vary among individuals. We examined variety among selected NK cell receptors expressed by NK cells from normal donors, as well as the distribution of select NK cell subsets and NK cell receptor expression over time in several individual donors. Peripheral blood mononuclear cells were evaluated using flow cytometry via fluorochrome-conjugated antibodies against a number of NK cell receptors. Results were analyzed for both mean fluorescence intensity (MFI) and the percent positive cells for each receptor. CD56(bright) and CD56(dim) NK cell subsets were also considered separately, as was variation in receptor expression in NK cell subsets over time in selected individuals. Through this effort, we provide ranges of NK cell surface receptor expression for a local adult population as well as provide insight into intra-individual variation.

High frequencies of polyfunctional CD8+ NK cells in chronic HIV-1 infection are associated with slower disease progression

Natural killer (NK) cells are effector and regulatory innate immune cells and play a critical role in the first line of defense against various viral infections. Although previous reports have indicated the vital contributions of NK cells to HIV-1 immune control, nongenetic NK cell parameters directly associated with slower disease progression have not been defined yet. In a longitudinal, retrospective study of 117 untreated HIV-infected subjects, we show that higher frequencies as well as the absolute numbers of CD8(+) CD3(-) lymphocytes are linked to delayed HIV-1 disease progression. We show that the majority of these cells are well-described blood NK cells. In a subsequent cross-sectional study, we demonstrate a significant loss of CD8(+) NK cells in untreated HIV-infected individuals, which correlated with HIV loads and inversely correlated with CD4(+) T cell counts. CD8(+) NK cells had modestly higher frequencies of CD57-expressing cells than CD8(-) cells, but CD8(+) and CD8(-) NK cells showed no differences in the expression of a number of activating and inhibiting NK cell receptors. However, CD8(+) NK cells exhibited a more functional profile, as detected by cytokine production and degranulation.

IMPORTANCE

We demonstrate that the frequency of highly functional CD8(+) NK cells is inversely associated with HIV-related disease markers and linked with delayed disease progression. These results thus indicate that CD8(+) NK cells represent a novel NK cell-derived, innate immune correlate with an improved clinical outcome in HIV infection.

T cell interleukin-15 surface expression in chimpanzees infected with human immunodeficiency virus

Interleukin-15 (IL-15) contributes to natural killer cell development and immune regulation. However, IL-15 and interferon-gamma (IFN-γ) production are significantly reduced during progression to AIDS. We have previously reported that HIV infected chimpanzees (Pan troglodytes) express CD3-CD8+ IFN-γ+ natural killer (NK) cells with an inverse correlation to plasma HIV viral load. To expand on our initial study, we examined a larger population of HIV infected chimpanzees (n=10). Whole blood flow cytometry analyses showed that recombinant gp120 (rgp120) or recombinant IL-15 induces specific CD3-CD8+ IFN-γ+ NK cells at higher levels than CD3+CD8+ IFN-γ+ T cells in HIV infected specimens. Interestingly, peripheral blood T cells exhibited 0.5-3% IL-15 surface Tcell/NKT cell phenotypes, and rIL-15 stimulation significantly (P<0.007) up-regulated CD4+CD25+ T cell expression. Importantly, these data demonstrate novel T cell interleukin-15 expression and indicate a plausible regulatory mechanism for this cell-type during viral infection.

Developing Combined HIV Vaccine Strategies for a Functional Cure

Increasing numbers of HIV-infected individuals have access to potent antiretroviral drugs that control viral replication and decrease the risk of transmission. However, there is no cure for HIV and new strategies have to be developed to reach an eradication of the virus or a natural control of viral replication in the absence of drugs (functional cure). Therapeutic vaccines against HIV have been evaluated in many trials over the last 20 years and important knowledge has been gained from these trials. However, the major obstacle to HIV eradication is the persistence of latent proviral reservoirs. Different molecules are currently tested in ART-treated subjects to reactivate these latent reservoirs. Such anti-latency agents should be combined with a vaccination regimen in order to control or eradicate reactivated latently-infected cells. New in vitro assays should also be developed to assess the success of tested therapeutic vaccines by measuring the immune-mediated killing of replication-competent HIV reservoir cells. This review provides an overview of the current strategies to combine HIV vaccines with anti-latency agents that could act as adjuvant on the vaccine-induced immune response as well as new tools to assess the efficacy of these approaches.

Cytokine production and dysregulation in HIV pathogenesis: lessons for development of therapeutics and vaccines

Numerous studies have characterized the cytokine modulation observed in human immunodeficiency virus (HIV) infected individuals, from initial infection through chronic disease. Progressive and non-progressive HIV infection models show the cytokine milieu differs in terms of production and responsiveness in these two groups, suggesting an understanding of the role cytokines play during infection is necessary for directing the immune response toward viral control. This review will cover cytokine induction and dysfunction during HIV pathogenesis, with a focus on the interplay between cytokines and transcription factors, T cell activation, and exhaustion. We highlight cytokines that have either vaccine adjuvant or therapeutic potential and discuss the need to identify key factors required for prevention of progression, clearance of infection, or protection from acquisition.

A plasma biomarker signature of immune activation in HIV patients on antiretroviral therapy

BACKGROUND

Immune activation is a strong predictor of disease progression in HIV infection. Combinatorial plasma biomarker signatures that represent surrogate markers of immune activation in both viremic and aviremic HIV patients on combination antiretroviral therapy (cART) have not been defined. Here, we identify a plasma inflammatory biomarker signature that distinguishes between both viremic and aviremic HIV patients on cART and healthy controls and examine relationships of this signature to markers of disease progression.

METHODS

Multiplex profiling and ELISA were used to detect 15 cytokines/chemokines, soluble IL-2R (sIL-2R), and soluble CD14 (sCD14) in plasma from 57 HIV patients with CD4 nadir <300 cells/µl and 29 healthy controls. Supervised and unsupervised analyses were used to identify biomarkers explaining variance between groups defined by HIV status or drug abuse. Relationships between biomarkers and disease markers were examined by Spearman correlation.

RESULTS

The majority (91%) of HIV subjects were on cART, with 38% having undetectable viral loads (VL). Hierarchical clustering identified a biomarker cluster in plasma consisting of two interferon-stimulated gene products (CXCL9 and CXCL10), T cell activation marker (sIL-2R), and monocyte activation marker (sCD14) that distinguished both viremic and aviremic HIV patients on cART from controls (p<0.0001) and were top-ranked in variables important in projection plots. IL-12 and CCL4 were also elevated in viremic and aviremic patients compared to controls (p<0.05). IL-12 correlated with IFNα, IFNγ, CXCL9, and sIL-2R (p<0.05). CXCL10 correlated positively with plasma VL and percentage of CD16+ monocytes, and inversely with CD4 count (p = 0.001, <0.0001, and 0.04, respectively).

CONCLUSION

A plasma inflammatory biomarker signature consisting of CXCL9, CXCL10, sIL-2R, and sCD14 may be useful as a surrogate marker to monitor immune activation in both viremic and aviremic HIV patients on cART during disease progression and therapeutic responses.

The role of IL-15 in challenging Acquired Immunodeficiency Syndrome

OBJECTIVE

To determine the functions of in vitro primed Natural Killer (NK) cells in Human Immunodeficiency Virus (HIV-1) infection and the role of IL-2, IL-12 and IL-15 in enhancing the NK survival and activity in terms of viral suppression and of purging of HIV provirus.

METHODS

Peripheral Blood Mononuclear Cells (PBMCs) and CD4+ T lymphocytes cells obtained from eight healthy donors were infected in vitro with HIV-1 and p24 was measured with and without IL-2, IL-12 and IL-15. We studied the effect of NK pulsed in vitro with IL-2, IL-12 and IL-15 on HIV replication by measurement of p-24 and DNA-provirus load when added into the culture of PBMCs and CD4+ T lymphocytes cells infected in vitro. We evaluated the effect of NK cells pulsed with IL-2, IL-12 and IL-15 on HIV replication and DNA-load into the culture of CD4+ T lymphocytes cells and PBMCs by trans-well chamber.

RESULTS

We found high levels of p24 in the supernatants of PBMCs and CD4+ T lymphocytes cells cultured with IL-2, IL-12, and IL-15. We observed a significant reduction of p24 in the culture both of infected PBMCs and CD4+ T lymphocytes cells in which was added NK pulsed with IL-15. We did not obtain the some results with NK pulsed with IL-2 and IL-12. We observed a power effect of NK pulsed with IL-15 on HIV-DNA. The trans-well chamber experiments showed that the effect of NK is both direct and both mediated by realizing of soluble factors.

CONCLUSIONS

This study highlights some important effects of IL 15 on NK in HIV patients anyway our results are preliminary and descriptive and others studies will be needed to provide rationale for immune therapies.

Natural killer cells: versatile roles in autoimmune and infectious diseases

Natural killer (NK) cells are essential members of innate immunity and they rapidly respond to a variety of insults via cytokine secretion and cytolytic activity. Effector functions of NK cells form an important first line of innate immunity against viral, bacterial and parasitic infections, as well as an important bridge for the activation of adaptive immune responses. The control of NK-cell activation and killing is now understood to be a highly complex system of diverse inhibitory and activatory receptor-ligand interactions, sensing changes in MHC expression. NK cells have a functional role in innate immunity as the primary source of NK-cell-derived immunoregulatory cytokines, which have been identified in target organs of patients suffering from autoimmune diseases, and play a critical role in early defense against infectious agents. This review focuses on recent research of NK cells, summarizing their potential immunoregulatory role in modulating autoimmunity and infectious diseases.

Innate and adaptive factors regulating human immunodeficiency virus type 1 genomic activation

Over the past decade, antiretroviral therapy targeting the viral entry process, reverse transcriptase, integrase, and protease, has prolonged the lives of people infected with human immunodeficiency virus type 1 (HIV-1). However, despite the development of more effective therapeutic strategies, reservoirs of viral infection remain. This review discusses molecular mechanisms surrounding the development of latency from the site of integration to pre- and post-integration maintenance of latency, including epigenetic factors. In addition, an overview of innate and adaptive cells important to HIV-1 infection are examined from the viewpoint of cytokines released and cytokines that act on these cells to explore an overall understanding of HIV-1 proviral genome activation. Finally, this review is discussed from the viewpoint of how an understanding of the interplay of all of these factors will help guide the next generation of therapies.

The macrophage in HIV-1 infection: from activation to deactivation?

Macrophages play a crucial role in innate and adaptative immunity in response to microorganisms and are an important cellular target during HIV-1 infection. Recently, the heterogeneity of the macrophage population has been highlighted. Classically activated or type 1 macrophages (M1) induced in particular by IFN-γ display a pro-inflammatory profile. The alternatively activated or type 2 macrophages (M2) induced by Th-2 cytokines, such as IL-4 and IL-13 express anti-inflammatory and tissue repair properties. Finally IL-10 has been described as the prototypic cytokine involved in the deactivation of macrophages (dM). Since the capacity of macrophages to support productive HIV-1 infection is known to be modulated by cytokines, this review shows how modulation of macrophage activation by cytokines impacts the capacity to support productive HIV-1 infection. Based on the activation status of macrophages we propose a model starting with M1 classically activated macrophages with accelerated formation of viral reservoirs in a context of Th1 and proinflammatory cytokines. Then IL-4/IL-13 alternatively activated M2 macrophages will enter into the game that will stop the expansion of the HIV-1 reservoir. Finally IL-10 deactivation of macrophages will lead to immune failure observed at the very late stages of the HIV-1 disease.

Natural killer cells in immunodefense against infective agents

Following the discovery of innate immune receptors, the topics of innate immunity and its role in defense against infective agents have recently blossomed into very active research fields, after several decades of neglect. Among innate immune cells, natural killer (NK) cells are endowed with the unique ability to recognize and kill cells infected with a variety of pathogens, irrespective of prior sensitization to these microbes. NK cells have a number of other functions, including cytokine production and immunoregulatory activities. Major advances have recently been made in the understanding of the role of NK cells in the physiopathology of infectious diseases. The cellular and molecular mechanisms regulating the acquisition of effector functions by NK cells and their triggering upon pathogenic encounters are being unraveled. The possibility that the power of NK cells could be harnessed for the design of innovative treatments against infections is a major incentive for biologists to further explore NK cell subset complexity and to identify the ligands that activate NK cell receptors.

New players in cytokine control of HIV infection

Cytokines are involved early in the pathogenesis of HIV infection and disease progression as a component of immunologic dysregulation and immunodeficiency and as determinants controlling virus replication. Several steps, before and after retroviral integration into host DNA in T cells and macrophages, are affected by cytokines whereas CCR5 and CXCR4 binding chemokines can interfere with viral entry. A growing number of potential players--including the gamma-common interleukin (IL)-7, IL-15, and IL-21 together with IL-17, IL-18, IL-19, IL-20, IL-23, and IL-27--are discussed in terms of their perturbation in HIV infection and of their effects on virus replication. Thus, an increasing intersection of HIV infection and the cytokine network represents a crucial determinant of virus replication and immunologic dysregulation and will likely play a key role in the development of effective strategies of HIV prevention and immunologic reconstitution.