Reservoirs for HIV infection and their persistence in the face of undetectable viral load

Molecular Pathogenesis of Human Immunodeficiency Virus-Associated Disease of Oropharyngeal Mucosal Epithelium

The oropharyngeal mucosal epithelia have a polarized organization, which is critical for maintaining a highly efficient barrier as well as innate immune functions. In human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) disease, the barrier and innate immune functions of the oral mucosa are impaired via a number of mechanisms. The goal of this review was to discuss the molecular mechanisms of HIV/AIDS-associated changes in the oropharyngeal mucosa and their role in promoting HIV transmission and disease pathogenesis, notably the development of opportunistic infections, including human cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. In addition, the significance of adult and newborn/infant oral mucosa in HIV resistance and transmission was analyzed. HIV/AIDS-associated changes in the oropharyngeal mucosal epithelium and their role in promoting human papillomavirus-positive and negative neoplastic malignancy are also discussed.

New hope for eradication of HIV from the body: the role of polymeric nanomedicines in HIV/AIDS pharmacotherapy

Human immunodeficiency virus continued to be the greatest challenge and killer disease of the 21st century despite the advent of potent highly active antiretroviral therapy which are limited by their severe adverse effects, significant drug interactions, frequent dosing, limited bioavailability, and less access to viral reservoir sites like macrophages. Nano-medicines are becoming new hopes in avoiding these shortcomings of conventional antiretroviral drugs. The emphasis of this review is mainly the application of polymers based nanomedicines in pharmacotherapy of HIV/AIDS. Most of the studies to date on this area are in vitro and human clinical trials are totally missed. However, many interesting points are uncovered through this review like the possibility of achieving high intracellular concentration of drugs, very good antiretroviral activity, improved bioavailability, reduced toxicity and release of the drugs from nanocarriers for long time reducing the need for frequent dosing. Indeed, a lot of assignments left behind for researchers to overcome the challenges hindering the wider application of nanomedicines in treatment of HIV/AIDS.

Neurologic complications of pediatric human immunodeficiency virus: implications for clinical practice and management challenges in the African setting

Approximately 3.4 million children worldwide are affected with human immunodeficiency virus (HIV)/AIDS with more than 90% of them residing in sub-Saharan Africa, according to the World Health Organization. A significant proportion of the children eligible for treatment with antiretroviral therapy are not currently receiving it. Neurologic manifestations of HIV are common in both adults and children. There is a large spectrum of neurologic conditions that may be caused by the virus; however, early invasion of the central nervous system by the virus, affecting the developing fetal and infant brain, is believed to result in the most common primary HIV-related central nervous system complication, HIV encephalopathy. This article summarizes the spectrum of neuro-HIV in children, focuses on the neurocognitive and behavioral sequelae, reviews the effects of treatment on the primary neurologic effects of the disease, and discusses the specific challenges of identifying and managing these problems in resource-limited contexts, such as those found on the African continent.

Nanotechnology and the treatment of HIV infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals.

Role of mitogen-activated protein kinases, nuclear factor-kappaB, and interferon regulatory factor 3 in Toll-like receptor 4-mediated activation of HIV long terminal repeat

Monocytes/macrophages are known to represent a potential reservoir of human immunodeficiency virus type 1 (HIV-1), which ensures continuous replication of the virus in patients on highly active antiretroviral therapy (HAART). Infected macrophages are a highly productive source of HIV-1 during infections with common opportunistic pathogens. Previous studies report that toll like receptors (TLR)s play a role in HIV-1 replication in macrophages. Here, we investigate the three main pathways activated through TLR4 and the interactions with the HIV-1 long terminal repeat (LTR), using human embryonic kidney (HEK) 293 cells expressing TLR4 and transfected with a luciferase reporter under the control of the HIV-1 LTR. Here, we demonstrate, that TLR4-mediated activation of HIV-LTR is largely governed by the nuclear factor-kappaB pathway. Neither of the mitogen-activated protein kinases ERK1/2, JNK, or p38 nor the transcription factor interferon regulatory factor 3 were involved in the direct transactivation of HIV-LTR through stimulation of TLR4.

Improved oral bioavailability and brain transport of Saquinavir upon administration in novel nanoemulsion formulations

The aim of this investigation was to develop novel oil-in-water (o/w) nanoemulsions containing Saquinavir (SQV), an anti-HIV protease inhibitor, for enhanced oral bioavailability and brain disposition. SQV was dissolved in different types of edible oils rich in essential polyunsaturated fatty acids (PUFA) to constitute the internal oil phase of the nanoemulsions. The external phase consisted of surfactants Lipoid-80 and deoxycholic acid dissolved in water. The nanoemulsions with an average oil droplet size of 100-200 nm, containing tritiated [(3)H]-SQV, were administered orally and intravenously to male Balb/c mice. The SQV bioavailability as well as distribution in different organ systems was examined. SQV concentrations in the systemic circulation administered in flax-seed oil nanoemulsions were threefold higher as compared to the control aqueous suspension. The oral bioavailability and distribution to the brain, a potential sanctuary site for HIV, were significantly enhanced with SQV delivered in nanoemulsion formulations. In comparing SQV in flax-seed oil nanoemulsion with aqueous suspension, the maximum concentration (C(max)) and the area-under-the-curve (AUC) values were found to be five- and threefold higher in the brain, respectively, suggesting enhanced rate and extent of SQV absorption following oral administration of nanoemulsions. The results of this study show that oil-in-water nanoemulsions made with PUFA-rich oils may be very promising for HIV/AIDS therapy, in particular, for reducing the viral load in important anatomical reservoir sites.

Cognitive functioning in school-aged children with vertically acquired HIV infection being treated with highly active antiretroviral therapy (HAART)

In today's era of highly active antiretroviral therapy (HAART), few children with HIV-1 infection experience severe central nervous system (CNS) manifestations indicative of encephalopathy. However, little is known about the neurocognitive strengths and weaknesses of HIV-infected children treated with HAART. This cross-sectional study is the first to systematically investigate the relation between cognitive functioning and medical markers in HIV-infected children and adolescents treated with HAART with varying levels of computed tomography (CT) brain scan abnormalities. The Wechsler Intelligence Scale for Children-Third Edition was administered to 41 vertically infected children (mean age = 11.2 years) treated with HAART for at least 1 year. Other procedures at the time of testing included CT brain scans and collection of CD4 cell counts and plasma HIV1 RNA PCR. Although global cognitive functioning among participants was in the Average range, children with minimal to moderate CT brain scan abnormalities scored significantly lower than children with normal scans on composite measures of cognitive functioning and five specific subtests, especially tasks involving executive functions. Furthermore, children with worse immune status (CD4+ counts < or = 500) scored lower on subtests measuring processing speed. Viral load was unrelated to cognitive test scores. Thus, children with HIV being treated with HAART remain at risk for developing CNS disease. Findings emphasize the importance of conducting neuropsychological assessments in this population, particularly for children with cortical atrophy and absolute CD4+ cell counts < or = 500.

The central nervous system is a viral reservoir in simian immunodeficiency virus--infected macaques on combined antiretroviral therapy: a model for human immunodeficiency virus patients on highly active antiretroviral therapy

This study used a simian immunodeficiency virus (SIV)-macaque model to determine whether virus persists in the central nervous system (CNS) of human immunodeficiency virus (HIV)-infected individuals in which plasma viral load has been suppressed by highly active antiretroviral therapy. SIV-infected macaques were treated with two reverse transcriptase inhibitors: PMPA (q- R-(2-phosphonomethoxypropyl)adenine)which does not cross the blood-brain barrier, and FTC (beta-2('),3(')-dideoxy-3 thia-5-fluorocytidine), which does. Viral DNA and RNA were quantitated in the brain after 6 months of suppression of virus replication in blood and cerebrospinal fluid (CSF). Viral DNA was detected in brain from all macaques, including those in which peripheral viral replication had been suppressed either by antiretroviral therapy or host immune responses. Significant neurological lesions were observed only in one untreated macaque that had active virus replication in the CNS. Expression of the inflammatory markers, major histocmopatibility complex (MHC) II and CD68 was significantly lower in macaques treated with PMPA/FTC. Thus, although antiretroviral treatment may suppress virus replication in the periphery and the brain and reduce CNS inflammation, viral DNA persists in the brain despite treatment. This suggests that the brain may serve as a long-term viral reservoir in HIV-infected individuals treated with antiretroviral drugs that suppress virus replication.

Amphotericin-B-mediated reactivation of latent HIV-1 infection

To date, attempts to eliminate HIV-1 infection from its latent reservoirs, a prerequisite for the development of a curative treatment strategy for HIV-1 infection, have been unsuccessful. We demonstrate that the FDA approved antifungal agent amphotericin B efficiently reactivates HIV-1 infection in THP89GFP cells, a model of HIV-1 latency in macrophages. Although amphotericin B does not directly reactivate latent HIV-1 infection in T cells (e.g., J89GFP), amphotericin-B-stimulated macrophages (THP89GFP cells or primary macrophages) when cocultured with J89GFP cells can induce HIV-1 reactivation in these cells in trans. Because of the close proximity of antigen presenting macrophages and T cells in the primary lymphoid organs, such interaction between antigen presenting macrophages and T cells are frequent, and it seems reasonable to assume that trans-reactivation strategies hold promise to also reactivate latent HIV-1 infection in vivo.

Rational design of drugs that induce human immunodeficiency virus replication

Drugs that induce human immunodeficiency virus type 1 (HIV-1) replication could be used in combination with highly active antiretroviral therapy (HAART) to reduce the size of the latent reservoir that is in part responsible for viral persistence. Protein kinase C (PKC) is a logical target for such drugs because it activates HIV-1 transcription through multiple mechanisms. Here we show that HIV-1 gene expression can be induced by potent synthetic analogues of the lipid second messenger diacylglycerol (DAG) synthesized on a five-member ring platform that reduces the entropy of binding relative to that of the more flexible DAG template. By varying the alkyl side chains of these synthetic DAG lactones, it was possible to maximize their potency and ability to render latently infected T cells sensitive to killing by an anti-HIV-1 immunotoxin while minimizing the side effects of CD4 and CXCR4 downregulation and tumor necrosis factor alpha upregulation. The two lead compounds, LMC03 and LMC07, regulated a series of PKC-sensitive genes involved in T-cell activation and induced viral gene expression in peripheral blood mononuclear cells from HIV-1-infected individuals. These studies demonstrate the potential for the rational design of agents that, in conjunction with HAART and HIV-specific toxins, can be used to decrease or eliminate the pool of latently infected reservoirs by forcing viral expression.

Selectively reduced tat mRNA heralds the decline in productive human immunodeficiency virus type 1 infection in monocyte-derived macrophages

The transcription and splicing of human immunodeficiency virus type 1 (HIV-1) mRNA in primary blood monocyte-derived macrophages (MDM) and CD4(+) peripheral blood lymphocytes (PBL) were compared to determine whether any differences might account for the slower noncytopathic infection of cells of the macrophage lineage. The expression of regulatory mRNAs during acute infection of MDM was delayed by about 12 h compared to that of PBL. In each cell type, an increase in spliced viral mRNAs slightly preceded virus production from the culture. Following the peak of productive infection, there was a proportional decrease in the expression of all regulatory mRNAs detected in PBL. In MDM, a dramatic additional decrease specifically in the tat mRNA species heralded a reduction in virus production. This decline in tat mRNA was reflected by a concomitant decrease in Tat activity in the cells and occurred with the same kinetics irrespective of the age of the cells when infected. Addition of exogenous Tat protein elicited a burst of virus production from persistently infected MDM, suggesting that the decrease in virus production from the cultures is a consequence of the reduction in tat mRNA levels. Our results show that modulation of HIV-1 mRNAs in macrophages during long-term infection, which is dependent on the period of infection rather than cell differentiation or maturation, results in a selective reduction of Tat protein levels at the commencement of a persistent, less productive phase of infection. Determination of the mechanism of this mRNA modulation may lead to novel targets for control of replication in these important viral reservoirs.

Increased affinity and stability of an anti-HIV-1 envelope immunotoxin by structure-based mutagenesis

HIV-infected cells are selectively killed by an immunotoxin in which a truncated form of Pseudomonas exotoxin A is joined to the variable region of a broadly neutralizing antibody (3B3) that recognizes the viral envelope glycoprotein (Env). To improve the efficacy of this molecule, we used three-dimensional structural information and phage selection data to design 23 single and multiple point mutations in the antibody variable region sequences that contact Env. Substituting an aromatic residue for an aspartate in the third complementarity-determining region of V(H) increased the potency of the immunotoxin by approximately 10-fold in a cell-killing assay. Detailed analysis of one such mutant, N31H/Q100eY, revealed both a higher affinity for monomeric and cell surface Env and an increased stability against aggregation compared with the starting immunotoxin. Conversion to a disulfide-linked two-chain format further stabilized the protein. N31H/Q100eY retained the ability to bind to Env from multiple viral isolates, to inhibit Env-mediated cell fusion, and to limit spreading viral infection in peripheral blood mononuclear cells. Such site-directed mutants may increase the utility of immunotoxins for reducing or eradicating persistent HIV-1 infection in humans.