Hydroxyurea and interleukin-6 synergistically reactivate HIV-1 replication in a latently infected promonocytic cell line via SP1/SP3 transcription factors

U1 and OM10.1. Myeloid Cell Lines as Surrogate Models of Reversible Proviral Latency

As already discussed for T cell lines, also myeloid cell lines as served as the earliest models of chronic HIV infection. They were particularly relevant in the late 1980s and early 1990s when most experimental in vitro infections were based on laboratory-adapted "T-cell tropic" strains of HIV-1, such as LAI/IIIB or others, that later were found to rely upon CXCR4 as coreceptor for viral entry in addition to CD4 as primary receptor. Although primary macrophages do express CXCR4 together with CD4, virus replication is much less efficient than that observed with CCR5-using "macrophage-tropic" strains, as discussed separately in this book. Although different myeloid cell lines have been used to generate models of chronic HIV-1 infection that could be used to investigate features of proviral reactivation, as reviewed in (Cassol et al. J Leukoc Biol 80:1018-1030, 2006), two cell lines in particular have been broadly used and will be here discussed: the U937-derived U1 and HL-60-derived OM-10.1.

S100A8 and S100A9, biomarkers of SARS-Cov2-infected patients, suppress HIV replication in primary macrophages

S100A8 and S100A9 are members of the Alarmin family; these proteins are abundantly expressed in neutrophils and form a heterodimer complex. Recently, both proteins were identified as novel biomarkers of SARS-CoV-2 infection and were shown to play key roles in inducing an aggressive inflammatory response by mediating the release of large amounts of pro-inflammatory cytokines, called the “cytokine storm.” Although co-infection with SARS-CoV-2 in people living with HIV-1 may result in an immunocompromised status, the role of the S100A8/A9 complex in HIV-1 replication in primary T cells and macrophages is still unclear. Here, we evaluated the roles of the proteins in HIV replication to elucidate their functions. We found that the complex had no impact on virus replication in both cell types; however, the subunits of S100A8 and S100A9 inhibits HIV in macrophages. These findings provide important insights into the regulation of HIV viral loads in SARS-CoV2 co-infection.

Sensing of HIV-1 by TLR8 activates human T cells and reverses latency

During HIV infection, cell-to-cell transmission results in endosomal uptake of the virus by target CD4+ T cells and potential exposure of the viral ssRNA genome to endosomal Toll-like receptors (TLRs). TLRs are instrumental in activating inflammatory responses in innate immune cells, but their function in adaptive immune cells is less well understood. Here we show that synthetic ligands of TLR8 boosted T cell receptor signaling, resulting in increased cytokine production and upregulation of surface activation markers. Adjuvant TLR8 stimulation, but not TLR7 or TLR9, further promoted T helper cell differentiation towards Th1 and Th17. In addition, we found that endosomal HIV induced cytokine secretion from CD4+ T cells in a TLR8-specific manner. TLR8 engagement also enhanced HIV-1 replication and potentiated the reversal of latency in patient-derived T cells. The adjuvant TLR8 activity in T cells can contribute to viral dissemination in the lymph node and low-grade inflammation in HIV patients. In addition, it can potentially be exploited for therapeutic targeting and vaccine development.

The Role of Macrophages in HIV-1 Persistence and Pathogenesis

Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4⁺ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of “shock and kill” to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current “shock and kill” strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.

HIV "shock and kill" therapy: In need of revision

The implementation of antiretroviral therapy 23 years ago has rendered HIV infection clinically manageable. However, the disease remains incurable, since it establishes latent proviral reservoirs, which in turn can stochastically begin reproducing viral particles throughout the patient's lifetime. Viral latency itself depends in large part on the silencing environment of the infected host cell, which can be chemically manipulated. "Shock and kill" therapy intends to reverse proviral quiescence by inducing transcription with pharmaceuticals and allowing a combination of antiretroviral therapy, host immune clearance and HIV-cytolysis to remove latently infected cells, leading to a complete cure. Over 160 compounds functioning as latency-reversing agents (LRAs) have been identified to date, but none of the candidates has yet led to a promising functional cure. Furthermore, fundamental bioinformatic and clinical research from the past decade has highlighted the complexity and highly heterogeneous nature of the proviral reservoirs, shedding doubt on the "shock and kill" concept. Alternative therapies such as the HIV transcription-inhibiting "block and lock" strategy are therefore being considered. In this review we describe the variety of existing classes of LRAs, discuss their current drawbacks and highlight the potential for combinatorial "shocktail" therapies for potent proviral reactivation. We also suggest investigating LRAs with lesser-known mechanisms of action, and examine the feasibility of "block and lock" therapy.

The Role of Macrophages in HIV-1 Persistence and Pathogenesis

Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4⁺ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of "shock and kill" to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current "shock and kill" strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.

HIV-1 infection renders brain vascular pericytes susceptible to the extracellular glutamate

Reduced pericytes' coverage of endothelium in the brain is one of the structural changes leading to breach of the blood-brain barrier during HIV infection. We previously showed in central memory T (T_CM) cells that HIV latency increases cellular susceptibility to DNA damage. In this study, we investigated susceptibility of primary brain pericytes infected with HIV-1 to DNA damage in response to glutamate and TNF-α, both known to induce neuronal death during chronic inflammatory conditions. To infect pericytes, we used a single-cycle HIV-1 pseudotyped with VSV-G envelope glycoprotein and maintained the cultures until latency was established. Our data indicate that pericytes silence HIV-1 expression at similar rate compared to primary T_CM cells. TNF-α and IL-1β caused partial reactivation of the virus suggesting that progression of disease and neuroinflammation might facilitate virus reactivation from latency. Significant increases in the level of γH2AX, which reflect DNA damage, were observed in infected cultures exposed to TNF-α and glutamate at day 2 post-infection. Glutamate, an excitatory neurologic stimuli, also caused increases in the γH2AX level in latently infected pericytes, whereas PARP and DNA-PK inhibitors caused reductions in cell population suggesting that HIV-1 latency affects repairs of single- and double-strand DNA breaks. For comparison, we also analyzed latently infected astrocytes and determined that DNA damage response in astrocytes is less affected by HIV-1. In conclusion, our results indicate that productive infection and HIV-1 latency in pericytes interfere with DNA damage response, rendering them vulnerable to the agents that are characteristic of chronic neuroinflammatory disease conditions.

Serum deprivation/starvation leads to reactivation of HIV-1 in latently infected monocytes via activating ERK/JNK pathway

Despite the high success rate, antiretroviral therapy does not cure the disease completely due to presence of latent viral reservoirs. Although several studies have addressed this issue earlier, the role of serum starvation/deprivation in HIV-1 latency has not been studied. So, we investigated the role of serum starvation in regulating HIV-1 latency. The impact of serum starvation on HIV-1 latency was assessed in latently infected monocytes U1 and T-cells J1.1. Serum starvation breaks HIV-1 latency in U1 cells. Under similar conditions, J1.1 cells failed to show reactivation of virus. We investigated the involvement of cell death pathway and autophagy during the serum starvation in viral reactivation. Inhibition of these pathways did not affect viral reactivation. Furthermore, other crucial factors like NF-κB, SP1 and AKT did not play any role in regulating viral latency. Here, we report that serum deprivation up-regulates ERK/JNK pathway. This leads to phosphorylation of c-Jun which plays an important role in viral reactivation. Treatment of cells with U0126, an ERK kinase inhibitor, potently inhibited viral replication. In summary, we show that serum starvation leads to reactivation of HIV-1 in latently infected monocytes through the ERK/JNK pathway.

In vitro reactivation of latent HIV-1 by cytostatic bis(thiosemicarbazonate) gold(III) complexes

Background

A number of cytostatic agents have been investigated for the ability to reactivate latent viral reservoirs, which is a major prerequisite for the eradication of HIV-1 infection. Two cytostatic bis(thiosemicarbazonate) gold(III) complexes (designated 1 and 2) were tested for this potential in the U1 latency model of HIV-1 infection.

Methods

Cell viability in the presence or absence of 1 and 2 was determined using a tetrazolium dye and evidence of reactivation was assessed by p24 antigen capture following exposure to a latency stimulant, phorbol myristate acetate (PMA) and or test compounds. The latency reactivation mechanism was explored by determining the effect of the complexes on protein kinase C (PKC), histone deacetylases (HDAC) and proinflammatory cytokine production.

Results

The CC₅₀ of the complexes in U1 cells were 0.53 ± 0.12 μM for 1 and 1.0 ± 0.4 μM for 2. In the absence of PMA and at non toxic concentrations of 0.2 and 0.5 μM, 1 and 2 significantly (p ≤ 0.02) reactivated virus in U1 cells by 2.7 and 2.3 fold respectively. In comparison, a 2.6 fold increase (p = 0.03) in viral reactivation was observed for hydroxyurea (HU), which was used as a cytostatic and latent HIV reactivation control. Viral reactivation was absent for the complexes during co-stimulation with PMA indicating the lack of an additive effect between the chemicals as well as an absence of inhibition of PMA induced HIV reactivation but for HU inhibition of the stimulant’s activity was observed (p = 0.01). Complex 1 and 2 activated PKC activity by up to 32% (p < 0.05) but no significant inhibition of HDAC was observed. Increases in TNF-α levels suggested that the reactivation of virus by the complexes may have been due to contributions from the latter and the activation of PKC.

Conclusion

The ethyl group structural difference between 1 and 2 seems to influence bioactivity with lower active concentrations of 1, suggesting that further structural modifications should improve specificity. The cytostatic effect of 1 and 2 and now HIV reactivation from a U1 latency model is consistent with that of the cytostatic agent, HU. These findings suggest that the complexes have a potential dual (cytostatic and reactivation) role in viral “activation/elimination”.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0680-3) contains supplementary material, which is available to authorized users.

Naturally occurring compounds elicit HIV-1 replication in chronically infected promonocytic cells

Since antiretroviral therapy suppresses but does not eradicate HIV-1 infection, methods to purge viral reservoirs are required. Many strategies involve the reactivation of chronically HIV infected cells to induce the expression of integrated viral genome. In this study, five bioactive compounds, the plant derivatives 1-cinnamoyl-3,11-dihydroxymeliacarpin (CDM), nordihydroguaiaretic acid (NDGA), and curcumin (Cur) and the synthetic stigmasterol analogs (22S,23S)-22,23-dihydroxystigmast-4-en-3-one (compound 1) and (22S,23S)-3 β -bromo-5 α ,22,23-trihydroxystigmastan-6-one (compound 2), were evaluated for their ability to elicit HIV replication in promonocytic (U1) and lymphocytic (H9+) HIV-1 chronically infected cells. The results revealed that natural compounds CDM, NDGA, and Cur were able to increase HIV-1 p24 antigen, determined by ELISA, only in latently infected promonocytic cells. CDM would reactivate HIV from latency by modulating the release of IL-6 and TNF- α , since the amount of both cytokines measured through ELISA significantly increased in U1 treated cells. Besides, NDGA increased ROS production, which might be related to the increase on p24 level observed in NDGA treated U1. These findings suggest that CDM, NDGA, and Cur might be candidates for further studies on latency-reversing therapeutics to eliminate latently HIV-1 reservoirs.

HIV-1 latency in monocytes/macrophages

Human immunodeficiency virus type 1 (HIV-1) targets CD4⁺ T cells and cells of the monocyte/macrophage lineage. HIV pathogenesis is characterized by the depletion of T lymphocytes and by the presence of a population of cells in which latency has been established called the HIV-1 reservoir. Highly active antiretroviral therapy (HAART) has significantly improved the life of HIV-1 infected patients. However, complete eradication of HIV-1 from infected individuals is not possible without targeting latent sources of infection. HIV-1 establishes latent infection in resting CD4⁺ T cells and findings indicate that latency can also be established in the cells of monocyte/macrophage lineage. Monocyte/macrophage lineage includes among others, monocytes, macrophages and brain resident macrophages. These cells are relatively more resistant to apoptosis induced by HIV-1, thus are important stable hideouts of the virus. Much effort has been made in the direction of eliminating HIV-1 resting CD4⁺ T-cell reservoirs. However, it is impossible to achieve a cure for HIV-1 without considering these neglected latent reservoirs, the cells of monocyte/macrophage lineage. In this review we will describe our current understanding of the mechanism of latency in monocyte/macrophage lineage and how such cells can be specifically eliminated from the infected host.

Interleukin-2 inhibits HIV-1 replication in some human T cell lymphotrophic virus-1-infected cell lines via the induction and incorporation of APOBEC3G into the virion

IL-2 has been used in culture of primary T cells to maintain cell proliferation. We have previously reported that IL-27 inhibits HIV-1 replication in primary T cells in the presence of IL-2. To gain a better understanding of the mechanisms involved in this inhibitory effect, we attempted to investigate in detail the effects of IL-27 and IL-2 using several cell lines. Unexpectedly, IL-27 did not inhibit HIV-1 in T cell lines, whereas IL-2 inhibited HIV-1 replication in the human T cell lymphotrophic virus (HTLV)-1-transformed T cell lines, MT-2, MT-4, SLB-1, and ATL-2. No effects were seen in HTLV-1-negative cell lines. Utilizing MT-2 cells, we demonstrated that IL-2 treatment inhibited HIV-1 syncytia-inducing ability and dose-dependently decreased supernatant p24 antigen levels by >90%. Using real time PCR and Western blot analysis, we observed that IL-2 treatment induced the host restriction factor, APOBEC3G with accumulation into the lower molecular mass active form as characterized by FPLC. Further analysis revealed that the virus recovered from IL-2-treated MT-2 cells had impaired replication competency. This was found to be due to incorporation of APOBEC3G into the virion despite the presence of Vif. These findings demonstrate a novel role for IL-2 in regulating production of infectious HIV-1 virions in HTLV-1-infected cells through the induction of APOBEC3G.

The role of cytokines in the establishment, persistence and eradication of the HIV reservoir

HIV persists in cellular and anatomical reservoirs during Highly Active Antiretroviral Therapy (HAART). In vitro studies as well as in vivo observations have identified cytokines as important factors regulating the immunological and virological mechanisms involved in HIV persistence. Immunosuppressive cytokines might contribute to the establishment of viral latency by dampening T cell activation and HIV production, thereby creating the necessary immuno-virological condition for the establishment of a pool of latently infected cells. Other cytokines that are involved in the maintenance of memory CD4(+) T cells promote the persistence of these cells during HAART. Conversely, proinflammatory cytokines may favor HIV persistence by exacerbating low levels of ongoing viral replication in lymphoid tissues even after prolonged therapy. The ability of several cytokines to interfere with the molecular mechanisms responsible for HIV latency makes them attractive candidates for therapeutic strategies aimed at reducing the pool of latently infected cells. In this article, we review the role of cytokines in HIV persistence during HAART and discuss their role as potential eradicating agents.

Kinetic characterization of newly discovered inhibitors of various constructs of human T-cell leukemia virus-1 (HTLV-1) protease and their effect on HTLV-1-infected cells

BACKGROUND

Human T-cell leukemia virus-1 (HTLV-1) was the first identified human retrovirus and was shown to be associated with diseases such as adult T-cell leukemia lymphoma and tropical spastic paraparesis/HTLV-1 associated myelopathy. Retroviral proteases (PRs) are essential for viral replication by processing viral Gag and Gag-(Pro)-Pol polyproteins during maturation. Full-length HTLV-1 PR is 125 residues long; whether the C-terminal region is required for catalytic activity is still controversial. In this study, we characterized the effect of C-terminal amino acids of HTLV-1 PR for PR activity and examined the binding of compounds identified by in silico screening. One compound showed inhibition against the virus in infected cells.

METHODS

Truncated (116-, 121- and 122-residue) forms of HTLV-1 PR were prepared and proteins from expression of the genes were purified. In silico screening was performed by docking small molecules into the active site of HTLV-1 PR. The kinetic constants k(cat), K(m), k(cat)/K(m) and inhibition constants K(i) for inhibitors identified by the computational screening were determined. Western blot and ELISA analyses were used to determine the effect of the most potent PR inhibitors on HTLV-1 protein processing in infected cells.

RESULTS

The constructs showed similar catalytic efficiency constants (k(cat)/K(m)); thus HTLV-1 PR C-terminal amino acids are not essential for full activity. Computational screening revealed new PR inhibitors and some were shown to be inhibitory in enzyme assays. In HTLV-1-infected cells, one of the small molecules inhibited HTLV-1 gag cleavage and decreased the amount of HTLV-1 p19 produced in the cells.

CONCLUSIONS

We have identified an HTLV-1 PR inhibitor that is biologically functional. Inhibitor screening will continue to develop possible drugs for therapy of HTLV-1 infection.

Evaluation of the effect of pyrimethamine, an anti-malarial drug, on HIV-1 replication

Co-infection of human immunodeficiency virus (HIV) with malaria is one of the pandemic problems in Africa and parts of Asia. Here we investigated the impact of pyrimethamine (PYR) and two other clinical anti-malarial drugs (chloroquine [CQ] or artemisinin [ART]) on HIV-1 replication. Peripheral blood mononuclear cells (PBMCs) or MT-2 cells were infected with HIV(NL4.3) strain and treated with different concentrations of the anti-malarial drugs. HIV-1 replication was measured using p24 ELISA. We show that 10 μM CQ and ART inhibited HIV-1 replication by 76% and 60% in PBMCs, respectively, but not in MT-2 cells. In contrast, 10 μM PYR enhanced HIV-1 replication in MT-2 cells by >10-fold. A series of molecular mechanism studies revealed that PYR increased intracellular HIV gag proteins without affecting the promoter or the reverse transcriptase activity. The effect of PYR was independent of HTLV-1 produced by MT-2 cells. Of interest, PYR treatment led to S-phase accumulation and increased AZT and d4T antiviral activity by ∼ 4-fold. Taken together, we show that PYR significantly enhances HIV-1 replication by affecting the cellular machinery. Our results could be relevant for the management of malaria and HIV particularly in regions where HIV-1 and malaria epidemics overlap.

Molecular mechanisms of HIV-1 persistence in the monocyte-macrophage lineage

The introduction of the highly active antiretroviral therapy (HAART) has greatly improved survival. However, these treatments fail to definitively cure the patients and unveil the presence of quiescent HIV-1 reservoirs like cells from monocyte-macrophage lineage. A purge, or at least a significant reduction of these long lived HIV-1 reservoirs will be needed to raise the hope of the viral eradication. This review focuses on the molecular mechanisms responsible for viral persistence in cells of the monocyte-macrophage lineage. Controversy on latency and/or cryptic chronic replication will be specifically evoked. In addition, since HIV-1 infected monocyte-macrophage cells appear to be more resistant to apoptosis, this obstacle to the viral eradication will be discussed. Understanding the intimate mechanisms of HIV-1 persistence is a prerequisite to devise new and original therapies aiming to achieve viral eradication.

Oral bacteria induce a differential activation of human immunodeficiency virus-1 promoter in T cells, macrophages and dendritic cells

INTRODUCTION

The human immunodeficiency virus (HIV) can integrate into T cells, macrophages and dendritic cells resulting in a latent infection. Reports have also demonstrated that various microbial and host cell factors can trigger HIV reactivation leading to HIV recrudescence, potentially undermining highly active antiretroviral therapies.

METHODS

This study evaluated the capacity of oral bacteria associated with chronic periodontal infections to stimulate HIV promoter activation in various cell models of HIV latency.

RESULTS

T cells (1G5) challenged with oral bacteria demonstrated a dose-response of HIV promoter activation with a subset of the bacteria, as well as kinetics that were generally similar irrespective of the stimuli. Direct bacterial challenge of the T cells resulted in increased activation of approximately 1.5- to 7-fold over controls. Challenge of macrophages (BF24) indicated different kinetics for individual bacteria and resulted in consistent increases in promoter activation of five fold to six fold over basal levels for all bacteria except Streptococcus mutans. Dendritic cells showed increases in HIV reactivation of 7- to 34-fold specific for individual species of bacteria.

CONCLUSION

These results suggested that oral bacteria have the capability to reactivate HIV from latently infected cells, showing a relationship of mature dendritic cells > immature dendritic cells > macrophages > or = T cells. Expression of various pattern recognition receptors on these various cell types may provide insight into the primary receptors/signaling pathways used for reactivation by the bacteria.

HIV-1 regulation of latency in the monocyte-macrophage lineage and in CD4+ T lymphocytes

The introduction in 1996 of the HAART raised hopes for the eradication of HIV-1. Unfortunately, the discovery of latent HIV-1 reservoirs in CD4+ T cells and in the monocyte-macrophage lineage proved the optimism to be premature. The long-lived HIV-1 reservoirs constitute a major obstacle to the eradication of HIV-1. In this review, we focus on the establishment and maintenance of HIV-1 latency in the two major targets for HIV-1: the CD4+ T cells and the monocyte-macrophage lineage. Understanding the cell-type molecular mechanisms of establishment, maintenance, and reactivation of HIV-1 latency in these reservoirs is crucial for efficient therapeutic intervention. A complete viral eradication, the holy graal for clinicians, might be achieved by strategic interventions targeting latently and productively infected cells. We suggest that new approaches, such as the combination of different kinds of proviral activators, may help to reduce dramatically the size of latent HIV-1 reservoirs in patients on HAART.

Oral infectious diseases: a potential risk factor for HIV virus recrudescence?

As the highly active antiretroviral therapy (HAART) has transitioned human immunodeficiency virus (HIV) infection into a 'chronic disease' management strategy, there is growing evidence that infection with non-HIV pathogens in HIV+ patients may have important public health implications in undermining HAART success and acquired immunodeficiency syndrome progression. Several bacterial and host cell products during infections with non-HIV pathogens have shown the capacity to regulate HIV replication in latently infected cells. A high prevalence of oral infections caused by bacteria, viruses and fungi has been described in HIV+ patients, including periodontal disease. The oral cavity appears to be a site of HIV pathogenesis and potential reservoir for the disease as HIV RNA and DNA forms are present in saliva as well as in gingival crevicular fluid, and oral epithelial cells are susceptible to either cell free or cell-associated HIV infection. The clinical and biological bases of potential associations between chronic oral inflammatory disorders, such as periodontal disease, and exacerbation of HIV viraemia have received little attention. This review attempts to evaluate the current understanding of HIV reactivation as a result of co-infection and/or inflammation induced by non-HIV pathogens in HIV-infected patients, and presents a hypothetic model about the potential role of periodontitis as a global oral infection that potentially contributes to HIV recrudescence.

Ephedrae herba, a component of Japanese herbal medicine Mao-to, efficiently activates the replication of latent human immunodeficiency virus type 1 (HIV-1) in a monocytic cell line

The persistence of latent human immunodeficiency virus type 1 (HIV-1)-infected cellular reservoirs, despite prolonged treatment with highly active antiretroviral therapy (HAART), represents a major hurdle to virus eradication. In this study, we evaluated the effect of Japanese herbal medicine on the induction of HIV-1 replication in latently infected monocytic cell line, U1, in order to eradicate virus efficiently. We found that Mao-to was able to induce HIV-1 replication either alone or in combination with tumor necrosis factor-alpha (TNF-alpha). Among the four components of Mao-to, only Ephedrae herba had strong effects in inducing HIV-1 replication. Analysis by Western blotting revealed that Ephedrae herba induced the nuclear translocation of nuclear factor-kappa B (NF-kappaB). Reporter assay data also showed that Ephedrae herba and, slightly, Mao-to activated the NF-kappaB promoter, indicating that these herbal agents may induce HIV-1 replication through NF-kappaB activation. These findings suggest that Mao-to and its component, Ephedrea herba, may be good candidates to augment HAART by inducing the expression of latent HIV-1 with the ultimate goal of eliminating persistent viral reservoirs in individuals infected with HIV-1.

IL-27, a novel anti-HIV cytokine, activates multiple interferon-inducible genes in macrophages

OBJECTIVE

IL-27 is a novel anti-HIV cytokine that inhibits HIV-1 replication in both CD4 T cells and monocyte-derived macrophages (MDM) as IFN-alpha does. To elucidate the mechanism of the antiviral activity, we compared the activity and the gene expression profile of IL-27-treated cells with that of IFN-alpha-treated cells.

METHODS

CD4 T cells and monocytes were isolated from peripheral blood mononuclear cells of healthy donors. CD4 T cells were stimulated with phytohemagglutinin, and MDM were induced from monocytes using macrophage-colony stimulating factor. HIV-1 replication was monitored by p24 antigen capture assay. The gene expression profiles were analysed using DNA microarray analysis. The increase in the expression of IFN-inducible genes (IFIG) was confirmed by the Quantigene plex assay.

RESULTS

Both cytokines preferentially inhibited HIV-1 replication in MDM compared with CD4 T cells. Quantitative real time polymerase chain reaction, enzyme-linked immunosorbent assay and neutralization assay using anti-IFN indicated that IFN-alpha, IFN-beta and IFN-gamma had no significant impact on IL-27-mediated HIV inhibition. DNA microarray analysis illustrated that IFN-alpha induced 33 and 18 IFIG in MDM and CD4 T cells, respectively. IL-27 induced 28 IFIG in MDM and five IFIG in CD4 T cells. The quantitative assay confirmed that IL-27 activated genes of RNA-dependent kinase, oligoadenylate synthetase, myxovirus protein, and apolipoprotein B messenger RNA-editing enzyme-catalytic polypeptide-like 3G.

CONCLUSION

IL-27 differentially regulates the gene expression between CD4 T cells and MDM. IL-27 significantly induces antiviral genes in MDM as does IFN-alpha, suggesting that IL-27 inhibits HIV replication in MDM via mechanism(s) similar to that of IFN-alpha.

Human cytomegalovirus and human immunodeficiency virus type-1 co-infection in human cervical tissue

Human cytomegalovirus (HCMV) and human immunodeficiency virus type-1 (HIV-1) infect the female genital tract. A human cervical explant model was developed to study single and dual infection by these viruses in the genital compartment. An HCMV strain expressing green fluorescent protein, and two clinical HCMV strains produced peak viral DNA copies at 14 to 21 days post-infection. Peak levels of HIV-1(Ba-L) p24 antigen occurred at 7 days post-infection. HIV-1(Ba-L) appeared to enhance HCMV in co-infected tissues. Singly and dually infected explants produced increased levels of cytokines IL-6, IL-8, and GRO-alpha in culture supernatants. Immunohistochemical and flow cytometric analysis showed HCMV infection of leukocytes with the phenotype CD45+/CD1a+/CD14+/HLA-DR+ but not stromal or endothelial cells. Cells expressing both GFP and HIV-1 p24 antigen were detected in co-infected tissues. The cervical explants provide an ex vivo human model for examining mechanisms of virus-virus interaction and pathogenesis in clinically relevant tissue.