Nanomedicine applications towards the cure of HIV

Combination antiretroviral therapy (cART) successfully suppresses HIV replication. However, daily and lifelong treatment is necessary to manage patient illness because cART neither eradicates infected cells from reservoirs nor reconstitutes HIV-specific immunity that could kill infected cells. Toward the cure of HIV, different nanomedicine classes have been developed with the following disease-modifying properties: to eradicate the virus by activation of latently infected CD4+ T-cells and reservoirs flushing; to kill the infected cells in the reservoirs by boosting of HIV-specific T cells; and to prevent infection by the use of microbicides with improved epithelial penetration and drug half-life. Preclinical and clinical trials consistently demonstrated that DermaVir, the most advanced nanomedicine, induces long-lasting memory T-cell responses and reduces viral load in comparison with placebo. DermaVir and the nanomedicine pipelines have the potential to improve the health of HIV-infected people at lower costs, to decrease antiretroviral drug exposure, and to contribute to the cure of HIV/AIDS.From the Clinical EditorDespite the leaps and bounds in the development of antiretroviral therapy, HIV remains a significant public health challenge. In this review, applications of nanomedicine- based technologies are discussed in the context of HIV treatment, including virus elimination by activation of latently infected CD4+ T-cells; infected cell elimination in the reservoirs by boosting HIV-specific T cells, and by preventing infection by the use of microbicides with improved epithelial penetration and drug half-life.     

Therapeutic potential of dendritic cell-based immunization against HBV in transgenic mice

Hepatitis B virus (HBV) transgenic mice that express HBV envelope proteins represent a model of chronic HBV infection suitable for the development of therapeutic immunization strategies. To address immunologically therapeutic effects induced by peptide-pulsed DCs, HBV transgenic mice were immunized with peptide-pulsed DCs, and the mice were killed after three times of immunization and the splenocytes were stimulated in vitro and detected by IFN-gamma ELISPOT and cytotoxic T lymphocyte (CTL) activity. The data demonstrated that HBV-specific CD8+ T cell response could be induced and CD8+ T cells had specific CTL activity. Furthermore, ELISA and fluorescent quantitative PCR were performed to detect the level of serum HBsAg and HBV DNA and the results demonstrated that HBV-specific peptide-pulsed DCs could significantly reduce the concentration of serum HBsAg and HBV DNA. The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were measured and no significant differences were observed between the different groups, which indicated that no hepatocellular injury occurred. Taken together, the data strongly demonstrated that CD8+ T cell responses and antiviral immunity were elicited in HBV transgenic mice, suggesting that peptide-pulsed DCs could elicit an effective antiviral immunity.     

HIV蛋白酶抑制剂与细胞凋亡

HIV感染人体后造成大量CD4 + T淋巴细胞的凋亡 ,从而破坏免疫系统 ,使机体无法抵抗病毒的入侵 ,导致免疫缺陷。目前的药物靶点都针对病毒本身 ,无法清除体内储存病毒的感染细胞 ,而HIV蛋白酶抑制剂治疗HIV/AIDS患者后可以减少HIV感染引起的细胞凋亡 ,帮助机体恢复免疫功能 ,并且这种作用与其抑制病毒的作用是相独立的 ,这提示了可以通过免疫重建的策略来治疗AIDS。本文综述了HIV蛋白酶抑制剂的研究和发展概况 ,其作用特点以及对细胞凋亡的影响。明确HIV蛋白酶抑制剂与细胞凋亡的关系 ,可以启发新的思路从细胞着手 ,通过恢复机体的免疫能力来对抗病毒 ,从根本上治疗AIDS。     

Sulfated pentagalloyl glucose (Y-ART-3) inhibits HIV replication and cytopathic effects in vitro, and reduces HIV infection in hu-PBL-SCID mice

To evaluate the efficacy of Y-ART-3 as an antiviral drug for HIV infections, its anti-HIV activity was assessed in vitro in cell culture systems and in vivo in hu-PBL-SCID mice. The results indicated that Y-ART-3 invariably inhibited not only HIV-1, but also HIV-2 and SIV strains. Its mechanism of action is ascribed to inhibition of viral adsorption to CD4-positive cells. In an in vivo study, human Ig- and CD4-positive cells were detected at similar levels in Y-ART-3-treated hu-PBL-SCID mice that were infected with HIV, and in PBS-treated control hu-PBL SCID mice that were not infected with HIV. If HIV positivity was calculated using the number of tests in which HIV was detected (i.e. PCR, and p24 from co-cultures of spleen and peritoneal wash cells), a significant effect of Y-ART-3 at a dose of 4 mg/kg was noted. Therefore, Y-ART-3 may be considered to be a potent and effective anti-HIV compound.     

HIV Neuropathogenesis: a Tight Rope Walk of Innate Immunity

During the course of HIV-1 disease, virus neuroinvasion occurs as an early event, within weeks following infection. Intriguingly, subsequent central nervous system (CNS) complications manifest only decades after the initial virus exposure. Although CNS is commonly regarded as an immune-privileged site, emerging evidence indicates that innate immunity elicited by the CNS glial cells is a critical determinant for the establishment of protective immunity. Sustained expression of these protective immune responses, however, can be a double-edged sword. As protective immune mediators, cytokines have the ability to function in networks and co-operate with other host/viral mediators to tip the balance from a protective to toxic state in the CNS. Herein, we present an overview of some of the essential elements of the cerebral innate immunity in HIV neuropathogenesis including the key immune cell types of the CNS with their respective soluble immune mediators: (1) cooperative interaction of IFN-γ with the host/virus factor (platelet-derived host factor (PDGF)/viral Tat) in the induction of neurotoxic chemokine CXCL10 by macrophages, (2) response of astrocytes to viral infection, and (3) protective role of PDGF and MCP-1 in neuronal survival against HIV Tat toxicity. These components of the cerebral innate immunity do not act separately from each other but form a functional immunity network. The ultimate outcome of HIV infection in the CNS will thus be dependent on the regulation of the net balance of cell-specific protective versus detrimental responses.     

抗HCV治疗对HCV/HIV混合感染者白细胞及CD4细胞影响的探讨

目的：了解抗HCV治疗对HCV/HIV混合感染者白细胞及CD4细胞的影响。方法回顾分析本科收治的12例HCV/HIV混合感染者在抗HCV治疗过程中白细胞及CD4细胞变化情况。结果12例接受PEG-IFNα-2a联合利巴韦林抗病毒治疗者，均出现不同程度的白细胞及CD4细胞计数的减少。其中同时使用含有齐多夫定的HAART方案者白细胞及CD4细胞计数减少最为明显。结论对于HCV/HIV混合感染者，在抗HCV治疗过程中应密切注意白细胞及CD4细胞的变化，抗HCV治疗前应尽可能更换含有齐多夫定片的HAART治疗方案。     

Vaccines and vaccine strategies against HIV

The HIV/AIDS pandemic is a global emergency and a preventive HIV vaccine is urgently needed. HIV has, however, proved a difficult pathogen to vaccinate against. This is largely because HIV has a very high mutation rate and can escape immune responses, it has a latent stage where it can rest silently integrated into host DNA, and neutralising antibodies that can neutralise diverse field strains have so far proved difficult to induce. There is however, considerable evidence now that HIV-specific CD4 and CD8 T cells can provide partial control of HIV replication and delay or prevent disease. Technologies to quantify and analyse HIV-specific T cells have advanced recently, and in particular ELISpot, intracellular cytokine staining and tetramer studies have provided clear analyses of the ability of HIV vaccines to induce T cell responses. The use of pools of overlapping HIV peptides as in vitro antigens has also provided a standardised reagent for accurate measurement of T cell responses. HIV protein vaccines have not induced broad neutralising antibodies or T cell responses and failed to protect humans in the only phase III efficacy trial yet completed. Viral vectors, such as canarypox, engineered to express HIV genes, have induced HIV-specific CD8 T cell responses in a minority of subjects in phase II trials and are proceeding to human efficacy trials. Currently, the most effective method of inducing CD8+ CTL immunity in non-human primates utilises priming with naked plasmid DNA and then boosting with recombinant viral vectors both encoding various parts of the HIV genome. Such vaccines have induced non-sterilising immunity to virulent Simian/Human immunodeficiency virus exposure in macaques and have entered phase I trials. Multiple other approaches are also being evaluated in what has become a global effort for a vaccine to prevent AIDS. Although an HIV vaccine is still a long way off, there is reason to be optimistic that a vaccine to prevent AIDS will eventually be developed.     

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suppresses the humoral and cell-mediated immune responses to influenza A virus without affecting cytolytic activity in the lung.

The immune response to influenza virus is exquisitely sensitive to suppression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); however, the cellular mechanisms underlying the suppressive effects of TCDD are unknown. Mice exposed to TCDD exhibited a dose-responsive increase in mortality following an otherwise non-lethal influenza virus infection. Given that cytotoxic T lymphocytes (CTL) are generally thought to resolve primary infections in the lung, we tested the hypothesis that exposure to TCDD suppresses T-cell responsiveness, leading to decreased CTL in the lung. After infection with influenza virus, naive CD8+ lymphocytes are activated and differentiate in the mediastinal lymph node (MLN). In mice exposed to TCDD and infected with influenza virus, the number of CD8+ MLN cells was reduced 60% compared to vehicle-treated mice. Moreover, MLN cells from TCDD-treated mice failed to develop cytolytic activity, and the production of interleukin (IL)-2 and interferon (IFN)-gamma was suppressed. Exposure to TCDD also altered the production of virus-specific antibodies, decreased the recruitment of CD8+ cells to the lung, reduced the percentage and number of bronchoalveolar lavage cells bearing a CTL phenotype (CD8+CD44hiCD62L(l) degrees ), and suppressed IL-12 levels in the lung. Despite our findings that exposure to TCDD suppressed T cell-dependent functions, the cytolytic activity of lung lavage cells from TCDD and vehicle treated mice was equivalent, and IFN gamma levels in the lungs of mice treated with TCDD were enhanced 10-fold. Thus, while exposure to TCDD suppressed a number of responses associated with the development of adaptive immunity to influenza virus, a direct link between these effects and enhanced susceptibility to influenza remains unclear.     

Cell cycle dysregulation during HIV infection: perspectives of a target based therapy

Human immunodeficiency virus (HIV) infection is characterized by a severe depletion of both CD4+ and CD8+ T cells, representing the result of virus-mediated killing of infected lymphocytes and the programmed cell death (apoptosis) of the uninfected bystander cells. Since only a small fraction of T lymphocytes are depleted by viral killing, apoptosis represents one of the most important mechanism of T cell death during HIV infection. Several apoptotic pathways can be triggered by the different stimuli: persistent T lymphocyte activation; altered death receptor (Fas, TNF-R, TRAIL R1-R2) membrane expression; viral proteins as well as gp120, Tat, and Nef; host factors such as the unbalance of cytokine synthesis by lymphocyte. Nevertheless, new evidences have demonstrated that the persistent HIV induced T cell activation and proliferation cause a cell cycle dysregulation resulting in a 5-fold increase in apoptotic cells. This perturbation represents a link between HIV infection, T cell activation, accelerated cell turnover and increased apoptosis and may thus represent a new therapeutic target. In fact, Interleukin-2 administration reverts such a cell cycle dysregulation and reduces activation induced T cell apoptosis. Herein we analyze the main HIV-related mechanisms of host cell death, that are dysregulation of the cell cycle and apoptosis induction of T lymphocytes. Finally, the role of cytokines at the site of infection and their association with apoptosis will be discussed to get insights into the immunological perturbations accounting for an accelerated disease progression. Current therapeutic approaches and strategies, like HAART and recombinant cytokines, that may, successfully, improve the immune-system dysregulation, are also discussed.     

An IL-15 dependent CD8 T cell response to selected HIV epitopes is related to viral control in early-treated HIV-infected subjects

In some early-treated HIV-positive patients, Structured Treatment Interruption (STI) is associated to spontaneous control of viral rebound. Thus, in this clinical setting, we analyzed the immunological parameters associated to viral control. Two groups of early treated patients who underwent STI were retrospectively defined, according to the ability to spontaneously control HIV replication (Controller and Non-controller). Plasma cytokine levels were analyzed by multiplex analysis. CD8 T cell differentiation was determined by polychromatic flow cytometry. Antigen-specific IFN-gamma production was analyzed by ELISpot and intracellular staining after stimulation with HIV-peptides. Long-term Elispot assays were performed in the presence or absence of IL-15. Plasma IL-15 was found decreased over a period of time in Non-Controller patients, whereas a restricted response to Gag (aa.167-202 and 265-279) and Nef (aa.86-100 and 111-138) immunodominant epitopes was more frequently observed in Controller patients. Interestingly, in two Non-Controller patients the CD8-mediated T cells response to immunodominant epitopes could be restored in vitro by IL-15, suggesting a major role of cytokine homeostasis on the generation of protective immunity. In early-treated HIV+ patients undergoing STI, HIV replication control was associated to CD8 T cell maturation and sustained IL-15 levels, leading to HIV-specific CD8 T cell responses against selected Gag and Nef epitopes.     

Cytokine and chemokine based control of HIV infection and replication

HIV infects and propagates into CD4+ T lymphocytes and macrophages, although many other cell types play an important role in virus spreading and pathogenesis. In addition to regulatory viral proteins, the cytokine network has early been implicated as a major controller of the plastic capacity of HIV to spread productively or rather remain silently integrated in the chromosomes of infected cells. The recent discovery of CCR5 and CXCR4 as essential entry co-receptors together with CD4 has highlighted a novel and potentially important step in the pharmacological hunt for more effective antiviral agents. In addition to regulate HIV expression and replication, several cytokines have demonstrated the capacity of up- or down-modulating chemokine receptors including CCR5 and CXCR4 with the consequence of influencing the susceptibility of T cells and macrophages to HIV infection. Pharmacological agents such as pertussis toxin B-oligomer have demonstrated HIV suppressive effects via non competitive binding of CCR5, whereas interferons or interleukin-16 (IL-16) can prevent post-entry steps in HIV expression. At the clinical level, several cytokines or their receptors are useful markers for monitoring disease progression and its consequence on the immune system. Cytokine-based therapy represents a realistic complementary approach to traditional antiretroviral therapy potentially capable of restoring important adaptive or innate immune functions ultimately curtailing HIV spreading and its consequences on the immune system, as exemplified by the experimental clinical use of IL-2.     

Apoptosis and HIV infection: about molecules and genes

During the evolution, the immune system has developed several strategies to fight viral infections. Apoptosis, autophagy and necrosis are different types of cell death that play a main role in the interactions between infective agents and the host, since they are often important defence mechanisms that have to avoid the spreading of the infection. In turn, viruses have evolved numerous ways to evade the host immune system by influencing the behaviour and functionality of several components. HIV infects and kills CD4+ T helper lymphocytes, preferentially those that are antigen-specific, but also encodes proteins with apoptotic capacities, including gp120, gp160, Tat, Nef, Vpr, Vpu, Vif and, last but not least, the viral protease. This latter protein can kill infected and uninfected lymphocytes through the action of several host molecules, mainly members of the tumor necrosis factor family, or via the mitochondrial apoptotic pathway. The proinflammatory state that is characteristic of both the acute and chronic phase of HIV infection facilitates cell death, and is an additional cause of immune damage. Potent antiretroviral drugs that are largely use in therapy can reduce apoptosis by different mechanisms, that not only include the diminished production of the virus by infected cells and the subsequent reduction of inflammation, but also a direct action on the viral protease. The role of the host genetic background is finally crucial in understanding the process of cell death in HIV infection.     

Differential toxicity of reactive metabolites of clindamycin and sulfonamides in HIV-infected cells: influence of HIV infection on clindamycin toxicity in vitro

Hypersensitivity adverse drug reactions are much more common among patients with acquired immunodeficiency syndrome (AIDS) than in the general population. High rates of hypersensitivity reactions to clindamycin have been noted. To investigate the role of reactive metabolites in these reactions, the authors studied toxicity of clindamycin and sulphamethoxazole (SMX) and their metabolites in uninfected and human immunodeficiency virus (HIV)-infected MOLT3 cells. Infected and uninfected cells were incubated with clindamycin or sulphamethoxazole hydroxylamine in increasing concentrations; reactive metabolites were generated by coincubation of cells and drug with murine microsomes and a microsomal activating system. Over a concentration range of 0 to 400 microM SMX-HA, there was a significant concentration-dependent increase in cell death in HIV-infected compared to uninfected cells (28%+/-3% vs 8%+/-5% at 400 microM, P < .05). In contrast, coincubation of cells with clindamycin, microsomes, and a microsomal activating system, as well as combinations of primaquine or pyrimethamine, was not associated with an increase in cell death among infected compared to uninfected cells. No concentration-toxicity was demonstrated. These data support the role of reactive metabolites in adverse drug reactions to sulfonamides during HIV infection, whereas alternate mechanism(s) may be responsible for increased rates of adverse drug reactions to clindamycin among patients with AIDS.     

慢性HBV感染者外周血淋巴细胞亚群的特征性研究

目的 分析慢性HBV感染者外周血T细胞亚群的特征及病程不同阶段的变化及意义.方法 采用流式细胞分析技术对75例慢性HBV感染者的外周血T细胞亚群进行检测,分析其差异及意义并与正常对照组相比较.结果 乙肝肝硬化患者的外周血白细胞及淋巴细胞绝对数低于慢性乙肝患者、携带者及正常对照组:与正常对照组比较,慢性乙肝、肝硬化患者的外周血CD4 T细胞、CD8 T细胞、NK细胞计数减少,并且随病情的进展逐渐降低.结论 HBV感染者体内存在T淋巴细胞亚群失衡和细胞免疫功能紊乱.外周血T淋巴细胞亚群随病情进展而减少,主要为CD4 T细胞、CD8 T细胞、NK细胞的减少.     

Antiviral and interferon-inducing activities of a new peptidomannan, KS-2, extracted from culture mycelia of Lentinus edodes

Oral (PO) administration of KS-2 to adult DDI mice resulted in a peak serum interferon (IF) titer of 800 units (U)/ml 20 hours after administration with detectable levels persisting until 30 hours. After intraperitoneal (IP) injection, a peak serum IF titer of 1,600 U/ml was detected and it followed the same time course as that of oral administration. The IF induced by KS-2 shared certain physico-chemical properties with the standard preparation of immune IF and was not neutralized by an antiserum against type I IF. In mice infected intranasally (IN) with influenza A2 (H2N2) virus, KS-2 was found to possess significant protective activities. Efficacy of the agent was evidenced by an increase in survivor number, a prolongation of mean survival time, an inhibition of the development of lung consolidation induced by the viral infection and a decrease in virus titer in lung tissues. Both PO and IP administrations of KS-2 protected mice against infection and significant antiviral activities were achieved not only by prophylactic but also chemotherapeutic administration. The protective activities of KS-2 against influenza virus infection in mice are discussed in view of the immunopotentiation of the host animals.     

HIV vaccines: progress to date

The quest for an effective and safe HIV-1 vaccine has been and still is the aspiration of many scientists and clinicians worldwide. Until recently, the hopes for an effective vaccine were thwarted by the disappointing results and early termination in September 2007 of the STEP study, which saw a subgroup of male vaccine recipients at an increased risk of HIV-1 infection, and the failure of earlier trials of vaccines based on recombinant envelope proteins to provide any level of protection. The results of the STEP study raised important questions in the field of HIV vaccines, including the use of recombinant adenovirus vectors as immunogens, the rationale for the development of T-cell-based vaccines and the development pathway for these vaccines, in terms of assessment of immunogenicity and the challenge models used. The study of neutralizing antibodies has demonstrated that the induction of high-titre, broadly neutralizing antibodies in the majority of recipients is likely to be highly problematic. However, the results of the RV144 Thai trial released in September 2009 have brought new optimism to the field. This study employed envelope-based immunogens delivered as a priming vaccination with a recombinant poxvirus vector and boosting with recombinant proteins. This regimen provided modest protection to HIV-1 infection in a low-risk population. Although the correlates of protection are currently unknown, extensive studies are underway to try to determine these. Neutralizing antibodies were not induced in the RV144 study; however, considerable titres of binding antibodies to HIV-1 viral envelope (Env) were. It is speculated that these antibodies may have provided a means of protection by a mechanism such as antibody-dependent cell-mediated cytotoxicity. In addition, no CD8+ T-cell responses were induced, but robust CD4+ T-cell responses were, and correlates of protection are being sought by analysing the quality of this aspect of the vaccine-induced immune response. The current paradigm for an optimal HIV-1 vaccine is to design immunogens and vaccination protocols that allow the induction of both broadly neutralizing humoral and broadly reactive and effective cell-mediated immunity, to act at sites of possible infection and post-infection, respectively. However, this is challenged by the results of the RV144 trial as neither of these responses were induced but modest protection was observed. Understanding the biology and immunopathology of HIV-1 early following infection, its modes of transmission and the human immune system's response to the virus should aid in the rational design of vaccines of increased efficacy.     

Analysis of immune cells in a patient with post-transfusion hepatitis caused by human cytomegalovirus

Cellular immune responses are associated with the pathogenesis of human cytomegalovirus (HCMV) hepatitis. We investigated a patient with post-transfusion HCMV hepatitis. A 9 year-old girl was involved in a traffic accident and suffered from traumatic damage to the left kidney and diaphragm and received a pelvic bone fracture. At emergency surgery she was transfused with 1200 ml of fresh whole donor blood. Abnormal liver function was observed in the 10 days after surgery. Titers of serum anti-HCMV IgG and IgM antibodies were elevated at 11, 17 and 25 weeks after operation. We analyzed the surface markers of peripheral blood mononuclear cells obtained 21 weeks after surgery. The CD4/CD8 ratio and the number of CD16 + CD56 decreased. We detected HCMV immediate early (IE) DNA in the fractionated peripheral blood cells (polymorphonuclear leukocytes, CD2+, CD4+ and CD8+ T lymphocytes) by polymerase chain reaction. The histology of liver biopsy at 23 weeks after operation showed the findings of acute hepatitis and the absence of HCMV IE antigen. It was considered that the immunosuppressive condition associated with the trauma, operation or transfusion itself induced the reactivation of HCMV or that transfused blood cells infected with HCMV caused reinfection. It was also speculated that HCMV hepatitis was not only due to the direct damage of hepatic cells by HCMV, but also due to the cellular immune responses associated with HCMV infection.