Thinking about HIV: the intersection of virus, neuroinflammation and cognitive dysfunction

Oscillatory markers of neuroHIV-related cognitive impairment and Alzheimer's disease during attentional interference processing

People with HIV (PWH) frequently experience mild cognitive decline, which is typically attributed to HIV-associated neurocognitive disorder (HAND). However, such declines could also be a sign of early Alzheimer's disease (AD) in older PWH. Distinguishing these two pathologies in PWH is exceedingly difficult, as there is a major knowledge gap regarding their neural and neuropsychological bases. In the current study, we begin to address this knowledge gap by recording magnetoencephalography (MEG) during a flanker interference task in 31 biomarker-confirmed patients on the AD spectrum (ADS), 25 older participants with HAND, and 31 cognitively-normal controls. MEG data was examined in the time-frequency domain using a data-driven approach. Our results indicated that the clinical groups (ADS/HAND) performed significantly worse than controls on the task and exhibited aberrations in interference-related theta and alpha oscillations, some of which were disease-specific. Specifically, patients (ADS/HAND) exhibited weaker interference activity in frontoparietal and cingulate cortices compared to controls, while the ADS group exhibited stronger theta interference than those with HAND in frontoparietal, occipital, and temporal cortices. These results reveal overlapping and distinct patterns of neurophysiological alterations among those with ADS and HAND in attentional processing centers and suggest the existence of unique oscillatory markers of each condition.

Role of MMP-13-77A/G polymorphism in HIV-associated neurocognitive disorders patients

Many diseases including HIV-Associated Neurocognitive Disorder (HAND) are impacted by matrix metalloproteinases (MMPs). MMP-13 play a role to cleave the collagen. MMP-13 contributes to peripheral neuropathy and induces unmyelinated axon degeneration. MMP-13-77A/G polymorphism has been associated to a lower level of MMP-13. MMP-13 have been linked to increased expression in a number of diseases including neurological disease. Hence we analyzed the effect of MMP-13-77A/G polymorphism in pateints with and without HAND. The PCR-Restriction fragment length polymorphism approach was used to genotype MMP-13-77A/G polymorphism. The MMP-13-77AG genotype was shown to be more prevalent in HAND patients than in controls and showed a risk for severe HAND (44.4% vs. 34.8%, P = 0.16, OR = 1.79). When compared to healthy controls, the MMP-13-77AG genotype was found to be prevalent in HAND patients (44.4 %vs. 38.2%, P = 0.66, OR = 1.26). MMP-13-77AG genotype was overrepresented (51.5% vs. 38.2%, OR = 1.70, P = 0.29) in HAND patients who had advanced HIV disease. In without HAND patients, the MMP-13-77AG genotype was found be lessor in advanced stage of HIV disease when compared with healthy controls and it was associated with a reduced risk for advancement in disease (38.2% vs. 11.82%, P = 0.03, OR = 0.18). Smokers were more likely to have the MMP-13-77AG genotype than non-smokers, indicating an elevated risk of HAND severity (60.0% vs. 40.0%, P = 0.50, OR = 2.29, 95%). In patients with and without HAND, alcohol intake enhanced the risk for developing HAND and its severity when the MMP-13-77GG genotype was present (P = 0.78, OR = 2.10, P = 0.78, OR = 2.10). In conclusion, Individuals with alcohol usage and the MMP-13-77GG genotype may have additive effect on HAND development and its severity. Individuals of without HAND and MMP-13-77AG genotype showed reduced risk for advancement of HIV disease.

Early Inflammatory Signatures Predict Subsequent Cognition in Long-Term Virally Suppressed Women With HIV

Immunologic function is an important determinant of cognition. Here we examined the contribution of early immune signatures to cognitive performance among HIV-infected, virally suppressed women (HIV+VS) and in HIV-uninfected (HIV-) women. Specifically, we measured serum inflammatory markers, developed combinatory immune signatures, and evaluated their associations with cognition. Forty-nine HIV+VS women in the Women’s Interagency HIV Study (WIHS) who achieved viral suppression shortly after effective antiretroviral therapy (ART) initiation, and 56 matched HIV− women were selected. Forty-two serum inflammatory markers were measured within 2 years of effective ART initiation for HIV+VS women, and at an initial timepoint for HIV− women. The same inflammatory markers were also measured approximately 1, 7, and 12 years later for all women. Of the 105 women with complete immune data, 83 (34 HIV+VS, 49 HIV−) also had cognitive data available 12 years later at ≥1 time points (median = 3.1). We searched for combinatory immune signatures by adapting a dynamic matrix factorization analytic method that builds upon Tucker decomposition followed by Ingenuity^® Pathway Analysis to facilitate data interpretation. Seven combinatory immune signatures emerged based on the Frobenius residual. Three signatures were common between HIV+VS and HIV− women, while four signatures were unique. These inflammatory signatures predicted subsequent cognitive performance in both groups using mixed-effects modeling, but more domain-specific associations were significant in HIV+VS than HIV− women. Leukocyte influx into brain was a major contributor to cognitive function in HIV+VS women, while T cell exhaustion, inflammatory response indicative of depressive/psychiatric disorders, microglial activity, and cytokine signaling predicted both global and domain-specific performance for HIV− women. Our findings suggest that immune signatures may be useful diagnostic, prognostic, and immunotherapeutic targets predictive of subsequent cognitive performance. Importantly, they also provide insight into common and distinct inflammatory mechanisms underlying cognition in HIV− and HIV+VS women.

Indolylarylsulfones, a fascinating story of highly potent human immunodeficiency virus type 1 non-nucleoside reverse transcriptase inhibitors

Indolylarylsulfones are a potent class of human immunodeficiency virus type 1 non-nucleoside reverse transcriptase inhibitors. In this review, the structure activity relationship (SAR) studies to improve the profile of sulfone L-737,126 discovered by Merck AG have been analysed with focus on introduction of the 3′,5′-dimethyl groups at the 3-phenylsulfonyl moiety, the 2-hydroxyethyl tail at the indole-2-carboxamide nitrogen, coupling of the carboxamide nitrogen with one or two glycinamide and alaninamide units, a fluorine atom at position 4 of the indole ring and correlation between configuration of the asymmetric centre and linker length. IAS derivatives look like promising drug candidates for the treatment of AIDS and related infections in combination with other antiretroviral agents.

Nucleoside Reverse Transcriptase Inhibitors (NRTIs) Induce Pathological Pain through Wnt5a-Mediated Neuroinflammation in Aging Mice

Highly Active Antiretroviral Therapy (HAART) has significantly contributed to the increase of HIV-infected survivors over 50 years of age. Unfortunately, patients are required to stay on long-term HAART, which may be causally related to the development of neurological problems such as chronic pain. Little is known about the contribution of HAART or its therapeutic agents to the pathogenesis of pain during aging. In this study, we determined the effect of nucleoside reverse transcriptase inhibitors (NRTIs) on the development of mechanical allodynia and the potential underlying mechanism in aging mice (15.5 months). We found that systemic administration of individual NRTIs, including ddC (2'-3'-dideoxycytidine), ddI (didanosine), AZT (3'-azido-3'-deoxythymidine) and d4T (2', 3'-didehydro-2', 3'-dideoxythymidine), induced allodynia in similar magnitudes and temporal profiles. We used ddC as a representative to investigate cellular and molecular processes induced by NRTIs in the spinal cord that probably underlie the development of allodynia. The results showed that ddC caused evident neuroinflammation in the spinal cord, suggested by the up-regulation of proinflammatory cytokines TNF-α and IL-1β and the reactions of microglia and astrocytes. In addition, we found that Wnt5a, a critical regulator of neuroinflammation, was also up-regulated. Pharmacological inhibition of Wnt5a blocked ddC-induced up-regulation of TNF-α and astrocyte reaction, while activation of Wnt5a signaling potentiated these processes. Furthermore, our data showed that inhibition of Wnt5a significantly reversed ddC-induced mechanical allodynia in aging mice. The results collectively suggest that NRTIs may contribute to the development of chronic pain in aging patients by inducing Wnt5a-regulated neuroinflammation.

Peripheral TNFα elevations in abstinent alcoholics are associated with hepatitis C infection

Substantial evidence supports the view that inflammatory processes contribute to brain alterations in HIV infection. Mechanisms recently proposed to underlie neuropathology in Alcohol Use Disorder (AUD) include elevations in peripheral cytokines that sensitize the brain to the damaging effects of alcohol. This study included 4 groups: healthy controls, individuals with AUD (abstinent from alcohol at examination), those infected with HIV, and those comorbid for HIV and AUD. The aim was to determine whether inflammatory cytokines are elevated in AUD as they are in HIV infection. Cytokines showing group differences included interferon gamma-induced protein 10 (IP-10) and tumor necrosis factor α (TNFα). Follow-up t-tests revealed that TNFα and IP-10 were higher in AUD than controls but only in AUD patients who were seropositive for Hepatitis C virus (HCV). Specificity of TNFα and IP-10 elevations to HCV infection status was provided by correlations between cytokine levels and HCV viral load and indices of liver integrity including albumin/globulin ratio, fibrosis scores, and AST/platelet count ratio. Because TNFα levels were mediated by HCV infection, this study provides no evidence for elevations in peripheral cytokines in "uncomplicated", abstinent alcoholics, independent of liver disease or HCV infection. Nonetheless, these results corroborate evidence for elevations in IP-10 and TNFα in HIV and for IP-10 levels in HIV+HCV co-infection.

Acute and chronic viral infections

A large number of viruses belonging to various families are able to cause central nervous system (CNS) infections and contribute significantly to burden of disease in humans globally. Most viral CNS infections are benign and self-limiting, and most remain undiagnosed. However, some viruses can cause severe inflammation, leading to morbidity and mortality, and result in severe long-term residual damage and neurologic dysfunction in patients. The potential of viruses to cause CNS inflammation greatly varies depending on host factors, such as age, sex, and genetic background, as well as viral factors. Despite the need for protection against viral invasion and replication, the extent of the immune response in the CNS is carefully regulated to prevent excessive inflammation and tissue destruction leading to irretrievable loss of neurons. Direct cytopathology is for many virus infections a major cause of neurologic symptoms; however, the antiviral immune response can in some instances contribute substantially to pathology. This chapter highlights a selection of clinically important neurotropic viruses that infect the CNS and cause neurologic diseases such as meningitis, encephalitis, and myelitis in humans, with a focus on neuropathologic findings.

Altered Associations between Pain Symptoms and Brain Morphometry in the Pain Matrix of HIV-Seropositive Individuals

Pain remains highly prevalent in HIV-seropositive (HIV+) patients despite their well-suppressed viremia with combined antiretroviral therapy. Investigating brain abnormalities within the pain matrix, and in relation to pain symptoms, in HIV+ participants may provide objective biomarkers and insights regarding their pain symptoms. We used Patient-Reported Outcome Measurement Information System (PROMIS®) pain questionnaire to evaluate pain symptoms (pain intensity, pain interference and pain behavior), and structural MRI to assess brain morphometry using FreeSurfer (cortical area, cortical thickness and subcortical volumes were evaluated in 12 regions within the pain matrix). Compared to seronegative (SN) controls, HIV+ participants had smaller surface areas in prefrontal pars triangularis (right: p = 0.04, left: p = 0.007) and right anterior cingulate cortex (p = 0.03) and smaller subcortical regions (thalamus: p ≤ 0.003 bilaterally; right putamen: p = 0.01), as well as higher pain scores (pain intensity-p = 0.005; pain interference-p = 0.008; pain-behavior-p = 0.04). Furthermore, higher pain scores were associated with larger cortical areas, thinner cortices and larger subcortical volumes in HIV+ participants; but smaller cortical areas, thicker cortices and smaller subcortical volumes in SN controls (interaction-p = 0.009 to p = 0.04). These group differences in the pain-associated brain abnormalities suggest that HIV+ individuals have abnormal pain responses. Since these abnormal pain-associated brain regions belong to the affective component of the pain matrix, affective symptoms may influence pain perception in HIV+ patients and should be treated along with their physical pain symptoms. Lastly, associations of lower pain scores with better physical or mental health scores, regardless of HIV-serostatus (p < 0.001), suggest adequate pain treatment would lead to better quality of life in all participants.

Soluble TLR2 and 4 concentrations in cerebrospinal fluid in HIV/SIV-related neuropathological conditions

HIV in the central nervous system (CNS) mainly infects microglial cells which are known to express toll-like receptors (TLRs). This paper aimed to study the role of soluble TLR2 (sTLR2), sTLR4, and other inflammatory markers in cerebrospinal fluid (CSF) in HIV/Simian immunodeficiency virus (SIV)-related neurological sequelae. We determined sTLR2 and sTLR4 levels in CSF and serum/plasma of SIV-infected rhesus macaques with and without neurological sequelae, as well as in HIV-infected patients with and without cognitive impairments and Alzheimer's disease (AD) patients and matched controls. CSF cytokines and chemokines levels were analyzed in macaques as markers of neuroinflammation, while neopterin and S100B CSF concentrations were measured in HIV-infected patients as microglial and astrocyte marker, respectively. We found detectable levels of sTLR2 and sTLR4 in CSF of macaques and humans. Furthermore, CSF sTLR2 and sTLR4 concentrations were higher in SIV-infected macaques with neurological sequelae compared to those without neurological complications (p = 0.0003 and p = 0.0006, respectively). CSF IL-8 and monocyte chemoattractant protein-1 (MCP-1) levels were elevated in macaques with neurological sequelae, and a positive correlation was found between CSF levels of sTLR2/4 and IL-8 and MCP-1. Also in humans, elevated CSF sTLR4 levels were found in HIV-infected patients with cognitive impairments compared to HIV-infected patients with normal cognition (p = 0.019). Unlike CSF S100B levels, neopterin correlated positively with sTLR2 and sTLR4. No difference was found in plasma and CSF sTLR2 and sTLR4 levels between AD patients and control subjects (p = 0.26). In conclusion, CSF sTLR2 and sTLR4 may play a role in HIV/SIV-related neuroinflammation and subsequent neuropathology.

Natural Products as Anti-HIV Agents and Role in HIV-Associated Neurocognitive Disorders (HAND): A Brief Overview

As the threat of Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) persists to rise, effective drug treatments are required to treat the infected people. Even though combination antiretroviral therapy (cART) provides stable viral suppression, it is not devoid of undesirable side effects, especially in persons undergoing long-term treatment. The present therapy finds its limitations in the emergence of multidrug resistance and accordingly finding new drugs and novel targets is the need of the hour to treat the infected persons and further to attack HIV reservoirs in the body like brain, lymph nodes to achieve the ultimate goal of complete eradication of HIV and AIDS. Natural products such as plant-originated compounds and plant extracts have enormous potential to become drug leads with anti-HIV and neuroprotective activity. Accordingly, many research groups are exploring the biodiversity of the plant kingdom to find new and better anti-HIV drugs with novel mechanisms of action and for HIV-associated neurocognitive disorders (HAND). The basic challenge that still persists is to develop viral replication-targeted therapy using novel anti-HIV compounds with new mode of action, accepted toxicity and less resistance profile. Against this backdrop, the World Health Organization (WHO) suggested the need to evaluate ethno-medicines for the management of HIV/AIDS. Consequently, there is need to evaluate traditional medicine, particularly medicinal plants and other natural products that may yield effective and affordable therapeutic agents. Although there are a good number of reports on traditional uses of plants to treat various diseases, knowledge of herbal remedies used to manage HIV/AIDS and HAND are scanty, vague and not well documented. In this review, plant substances showing a promising action that is anti-HIV and HAND will be explored along with what they interact. Since some plant substances are also known to modulate several cellular factors which are also involved in the replication of HIV and hence their role as potential candidates will be discussed. HIV/AIDS being an exceptional epidemic, demands an exceptional approach and that forms very much focus for the current review.

Imaging neuroinflammation? A perspective from MR spectroscopy

Neuroinflammatory mechanisms contribute to the brain pathology resulting from human immunodeficiency virus (HIV) infection. Magnetic resonance spectroscopy (MRS) has been touted as a suitable method for discriminating in vivo markers of neuroinflammation. The present MRS study was conducted in four groups: alcohol dependent (A, n = 37), HIV-infected (H, n = 33), alcohol dependent + HIV infected (HA, n = 38) and healthy control (C, n = 62) individuals to determine whether metabolites would change in a pattern reflecting neuroinflammation. Significant four-group comparisons were evident only for striatal choline-containing compounds (Cho) and myo-inositol (mI), which follow-up analysis demonstrated were due to higher levels in HA compared with C individuals. To explore the potential relevance of elevated Cho and mI, correlations between blood markers, medication status and alcohol consumption were evaluated in H + HA subjects. Having an acquired immune deficiency syndrome (AIDS)-defining event or hepatitis C was associated with higher Cho; lower Cho levels, however, were associated with low thiamine levels and with highly active antiretroviral HIV treatment (HAART). Higher levels of mI were related to greater lifetime alcohol consumed, whereas HAART was associated with lower mI levels. The current results suggest that competing mechanisms can influence in vivo Cho and mI levels, and that elevations in these metabolites cannot necessarily be interpreted as reflecting a single underlying mechanism, including neuroinflammation.

Nanomedicines in the future of pediatric therapy

Nanotechnology has become a key tool to overcome the main (bio)pharmaceutical drawbacks of drugs and to enable their passive or active targeting to specific cells and tissues. Pediatric therapies usually rely on the previous clinical experience in adults. However, there exists scientific evidence that drug pharmacokinetics and pharmacodynamics in children differ from those in adults. For example, the interaction of specific drugs with their target receptors undergoes changes over the maturation of the different organs and systems. A similar phenomenon is observed for toxicity and adverse effects. Thus, it is clear that the treatment of disease in children cannot be simplified to the direct adjustment of the dose to the body weight/surface. In this context, the implementation of innovative technologies (e.g., nanotechnology) in the pediatric population becomes extremely challenging. The present article overviews the different attempts to use nanotechnology to treat diseases in the pediatric population. Due to the relevance, though limited available literature on the matter, we initially describe from preliminary in vitro studies to preclinical and clinical trials aiming to treat pediatric infectious diseases and pediatric solid tumors by means of nanotechnology. Then, the perspectives of pediatric nanomedicine are discussed.

Perinatally acquired HIV infection: long-term neuropsychological consequences and challenges ahead

Over the past three decades, perinatal HIV infection in the United States has evolved from a fatal disease to a manageable chronic illness. As the majority of youth with perinatal HIV infection age into adolescence and adulthood, management of this stigmatizing, transmittable disease in the backdrop of a cadre of environmental stressors presents challenges beyond those of other chronic illnesses. The neurologic and neuropsychological consequences of this neurotropic virus have important implications for the successful navigation of responsibilities related to increasingly independent living of this aging population. This article will review the neurologic and neuropsychological consequences of perinatal HIV infection and concomitant factors in the era of highly active antiretroviral therapy and will provide an overview of the neuropathology, pathogenesis, neuroimaging findings, and treatment of perinatal HIV infection, as well as recommendations for service provision and future research.

Type I Interferon at the Interface of Antiviral Immunity and Immune Regulation: The Curious Case of HIV-1

Type I interferon (IFN-I) play a critical role in the innate immune response against viral infections. They actively participate in antiviral immunity by inducing molecular mechanisms of viral restriction and by limiting the spread of the infection, but they also orchestrate the initial phases of the adaptive immune response and influence the quality of T cell immunity. During infection with the human immunodeficiency virus type 1 (HIV-1), the production of and response to IFN-I may be severely altered by the lymphotropic nature of the virus. In this review I consider the different aspects of virus sensing, IFN-I production, signalling, and effects on target cells, with a particular focus on the alterations observed following HIV-1 infection.

Chemokine co-receptor CCR5/CXCR4-dependent modulation of Kv2.1 channel confers acute neuroprotection to HIV-1 glycoprotein gp120 exposure

Infection with human immunodeficiency virus-1 (HIV-1) within the brain has long been known to be associated with neurodegeneration and neurocognitive disorder (referred as HAND), a condition characterized in its early stages by declining cognitive function and behavioral disturbances. Mechanistically, the HIV-1 coat glycoprotein 120 (gp120) has been suggested to be a critical factor inducing apoptotic cell death in neurons via the activation of p38 mitogen-activated protein kinase (MAPK), upon chronic exposure to the virus. Here we show that acute exposure of neurons to HIV-1 gp120 elicits a homeostatic response, which provides protection against non-apoptotic cell death, involving the major somatodendritic voltage-gated K⁺ (Kv) channel Kv2.1 as the key mediator. The Kv2.1 channel has recently been shown to provide homeostatic control of neuronal excitability under conditions of seizures, ischemia and neuromodulation/neuroinflammation. Following acute exposure to gp120, cultured rat hippocampal neurons show rapid dephosphorylation of the Kv2.1 protein, which ultimately leads to changes in specific sub-cellular localization and voltage-dependent channel activation properties of Kv2.1. Such modifications in Kv2.1 are dependent on the activation of the chemokine co-receptors CCR5 and CXCR4, and subsequent activation of the protein phosphatase calcineurin. This leads to the overall suppression of neuronal excitability and provides neurons with a homeostatic protective mechanism. Specific blockade of calcineurin and Kv2.1 channel activity led to significant enhancement of non-apoptotic neuronal death upon acute gp120 treatment. These observations shed new light on the intrinsic homeostatic mechanisms of neuronal resilience during the acute stages of neuro-HIV infections.

Temperature- and pH-sensitive Polymeric Micelles for Drug Encapsulation, Release and Targeting

More than 50% of the drugs in the market and 70% of the new candidates are poorly water soluble according to the Biopharmaceutic Classification System (BCS(. Poor aqueous solubility and physico-chemical stability of drugs in biological fluids remain key limitations in oral, parenteral and transdermal administration and contribute to an increase the drug attrition rate. Motivated by the outbreak of nanotechnology, different nanocarriers made of lipids and polymers have been designed and developed to address these limitations. Moreover, robust platforms were exploited to achieve the temporal and spatial release of drugs, thus constraining the systemic exposure to toxic agents and the appearance of severe adverse effects and improving the safety ratio. Owing to unique features such as (i( great chemical flexibility, (ii( capacity to host, solubilize and physico-chemically stabilize poorly water soluble drugs, (iii( ability to accumulate selectively in highly vascularized solid tumors and (iv( ability of single amphiphile molecules (unimers( to inhibit the activity of different pumps of the ATP-binding cassette superfamily (ABCs(, polymeric micelles have emerged as one of the most versatile nanotechnologies. Despite their diverse applications to improve the therapeutic outcomes, polymeric micelles remain clinically uncapitalized. The present chapter overviews the most recent applications of temperature- and pH-responsive polymeric micelles for the encapsulation, release and targeting of drugs and discusses the perspectives for these unique nanocarriers in the near future.

Wingless-type mammary tumor virus integration site family, member 5A (Wnt5a) regulates human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein 120 (gp120)-induced expression of pro-inflammatory cytokines via the Ca2+/calmodulin-dependent protein kinase II (CaMKII) and c-Jun N-terminal kinase (JNK) signaling pathways

BACKGROUND

HIV-1 infection causes chronic neuroinflammation in the central nervous system (CNS).

RESULTS

The spinal cytokine up-regulation induced by HIV-1 gp120 protein depends on Wnt5a/CaMKII and/or Wnt5a/JNK pathways.

CONCLUSION

gp120 stimulates cytokine expression in the spinal cord dorsal horn by activating Wnt5a signaling.

SIGNIFICANCE

The finding reveals Wnt signaling-mediated novel mechanisms by which HIV-1 may cause neuroinflammation. Chronic expression of pro-inflammatory cytokines critically contributes to the pathogenesis of HIV-associated neurological disorders (HANDs), but the host mechanism that regulates the HIV-induced cytokine expression in the CNS remains elusive. Here, we present evidence for a crucial role of Wnt5a signaling in the expression of pro-inflammatory cytokines in the spinal cord induced by a major HIV-envelope protein, gp120. Wnt5a is mainly expressed in spinal neurons, and rapidly up-regulated by intrathecal injection (i.t.) of gp120. We show that inhibition of Wnt5a by specific antagonists blocks gp120-induced up-regulation of IL-1β, IL-6, and TNF-α in the spinal cord. Conversely, injection (i.t.) of purified recombinant Wnt5a stimulates the expression of these cytokines. To elucidate the role of the Wnt5a-regulated signaling pathways in gp120-induced cytokine expression, we have focused on CaMKII and JNKs, the well characterized down-stream targets of Wnt5a signaling. We find that Wnt5a is required for gp120 to activate CaMKII and JNK signaling. Furthermore, we demonstrate that the Wnt5a/CaMKII pathway is critical for the gp120-induced expression of IL-1β, whereas the Wnt5a/JNK pathway is for TNF-α expression. Meanwhile, the expression of IL-6 is co-regulated by both pathways. These results collectively suggest that Wnt5a signaling cascades play a crucial role in the regulation of gp120-induced expression of pro-inflammatory cytokines in the CNS.

Intranasal administration of antiretroviral-loaded micelles for anatomical targeting to the brain in HIV

AIM

To investigate the intranasal administration of poly(ethylene oxide)-poly(propylene oxide) polymeric micelles loaded with high payloads of the first-line antiretroviral drug efavirenz for targeting to the CNS.

METHODS & MATERIALS

The effect of micellar size and composition and drug payload was assessed, employing simple micelles made of a highly hydrophilic copolymer, poloxamer F127, loaded with 20 mg/ml drug and mixed micelles containing 75% of a poloxamine of intermediate hydrophobicity, T904, and 25% F127 loaded with 20 and 30 mg/ml drug. F127 confers high physical stability, while T904 substantially improves the encapsulation capacity of the micelles.

RESULTS

The bioavailability of the drug in the CNS was increased fourfold and the relative exposure index (ratio between the area under the curve in the CNS and plasma) was increased fivefold with respect to the same system administered intravenously.

CONCLUSION

These findings demonstrate the potential of this scalable and cost-viable strategy to address the HIV sanctuary in the CNS.

Change in brain magnetic resonance spectroscopy after treatment during acute HIV infection

OBJECTIVE

Single voxel proton magnetic resonance spectroscopy (MRS) can be used to monitor changes in brain inflammation and neuronal integrity associated with HIV infection and its treatments. We used MRS to measure brain changes during the first weeks following HIV infection and in response to antiretroviral therapy (ART).

METHODS

Brain metabolite levels of N-acetyl aspartate (NAA), choline (tCHO), creatine (CR), myoinositol (MI), and glutamate and glutamine (GLX) were measured in acute HIV subjects (n = 31) and compared to chronic HIV+individuals (n = 26) and HIV negative control subjects (n = 10) from Bangkok, Thailand. Metabolites were measured in frontal gray matter (FGM), frontal white matter (FWM), occipital gray matter (OGM), and basal ganglia (BG). Repeat measures were obtained in 17 acute subjects 1, 3 and 6 months following initiation of ART.

RESULTS

After adjustment for age we identified elevated BG tCHO/CR in acute HIV cases at baseline (median 14 days after HIV infection) compared to control (p = 0.0014), as well as chronic subjects (p = 0.0023). A similar tCHO/CR elevation was noted in OGM; no other metabolite abnormalities were seen between acute and control subjects. Mixed longitudinal models revealed resolution of BG tCHO/CR elevation after ART (p = 0.022) with tCHO/CR similar to control subjects at 6 months.

INTERPRETATION

We detected cellular inflammation in the absence of measurable neuronal injury within the first month of HIV infection, and normalization of this inflammation following acutely administered ART. Our findings suggest that early ART may be neuroprotective in HIV infection by mitigating processes leading to CNS injury.

Human immunodeficiency virus and the central nervous system

Human immunodeficiency virus (HIV) continues to infect large numbers of people, including children, worldwide. The virus produces much of its clinical impact by infecting cellular components of the immune system. However, HIV also has the propensity to infect the brain, where it can induce substantial pathology and impair brain function. Highly active antiretroviral therapy has reduced the severity and prevalence of HIV-associated neurocognitive disorders. Nevertheless, substantial morbidity and mortality continue to stem from HIV infection of the nervous system. This article reviews the pathogenesis of HIV-induced central nervous system disease, the pathological and clinical effects of HIV infection within the brain, and the controversies and challenges of the use of highly active antiretroviral therapy for prevention and treatment of HIV-induced central nervous system dysfunction.

Poly(ε-caprolactone), Eudragit® RS 100 and poly(ε-caprolactone)/Eudragit® RS 100 blend submicron particles for the sustained release of the antiretroviral efavirenz

The design of simple and scalable drug delivery systems to target the central nervous system (CNS) could represent a breakthrough in the addressment of the HIV-associated neuropathogenesis. The intranasal (i.n.) route represents a minimally invasive strategy to surpass the blood-brain barrier, though it demands the use of appropriate nanocarriers bearing high drug payloads and displaying sufficiently long residence time. The present work explored the development of submicron particles made of poly(ε-caprolactone) (PCL), Eudragit(®) RS 100 (RS a copolymer of ethylacrylate, methylmethacrylate and methacrylic acid esterified with quaternary ammonium groups) and their blends, loaded with the first-choice antiretroviral efavirenz (EFV) as an approach to fine tune the particle size and the release kinetics. Particles displaying hydrodynamic diameters between 90 and 530 nm were obtained by two methods: nanoprecipitation and emulsion/solvent diffusion/evaporation. In general, the former resulted in smaller particles and narrower size distributions. The encapsulation efficiency was greater than 94%, the drug weight content approximately 10% and the yield in the 72.5-90.0% range. The highly positive surface (>+30 mV) rendered the suspensions physically stable for more than one month. In vitro release assays indicated that the incorporation of the poly(methacrylate) into the composition reduced the burst effect and slowed the release rate down with respect to pure poly(ε-caprolactone) particles. The analysis of the release profile indicated that, in all cases, the kinetics adjusted well to the Higuchi model with R(adj)(2) values >0.9779. These findings suggested that the release was mainly controlled by diffusion. In addition, when data were analyzed by the Korsmeyer-Peppas model, n values were in the 0.520-0.587 range, indicating that the drug release was accomplished by the combination of two phenomena: diffusion and polymer chain relaxation. Based on ATR/FT-IR analysis that investigated drug/polymer matrix interactions, the potential role of the hydrophobic interactions of C-F groups of EFV with carbonyl groups in the backbone of PCL and poly(methacrylate) could be ruled out. The developed EFV-loaded particles appear as a useful platform to investigate the intranasal administration to increase the bioavailability in the CNS.

Immune surveillance in the central nervous system

The CNS, which consists of the brain and spinal cord, is continuously monitored by resident microglia and blood-borne immune cells such as macrophages, dendritic cells and T cells to detect for damaging agents that would disrupt homeostasis and optimal functioning of these vital organs. Further, the CNS must balance between vigilantly detecting for potentially harmful factors and resolving any immunological responses that in themselves can create damage if left unabated. We discuss the physiological roles of the immune sentinels that patrol the CNS, the molecular markers that underlie their surveillance duties, and the consequences of interrupting their functions following injury and infection by viruses such as JC virus, human immunodeficiency virus, herpes simplex virus and West Nile virus.

Cytokine levels in CSF and neuropsychological performance in HIV patients

HIV-associated dementia and its precursors are frequently observed complications of HIV infection, even in the presence of combination antiretroviral treatment (cART). The development, surveillance and treatment of this condition are still not completely understood. Cytokines, as immunological transmitters, may be one key to gaining a deeper understanding of the disease. A total of 33 HIV-positive male patients were evaluated by neuropsychological testing, lumbar and venous puncture, neuroimaging and neurological examination. The cytokine content in the CSF (cerebrospinal fluid) was examined by a solid-phase protein array. The Digit-Symbol Test, contraction time analysis, Rey-Osterrieth Figure and Grooved-Pegboard Test showed inferior results in the presence of an inflammatory CSF environment, whereas neuroprotective or anti-inflammatory conditions were correlated to better results in contraction time analysis. Higher CSF levels of cytokines were independently correlated with the duration of HIV infection. The study showed a correlation of cytokine levels in the CSF of HIV patients with test results of their neuropsychological functioning. The effect was pronounced with regard to the more complex executive tasks. Determining CSF cytokine levels may be a useful supplement to the assessment of HIV patients and contribute helpful information to predict neurocognitive performance. Therapeutic strategies to ameliorate a negative impact of an altered cytokine milieu may aid in slowing the evolution of neurocognitive dysfunction.

Plasma gelsolin accumulates in macrophage nodules in brains of simian immunodeficiency virus infected rhesus macaques

Plasma gelsolin (pGSN), an isoform 1, is secreted by various types of cells in the central nervous system (CNS) and periphery, but not by the liver. pGSN circulates in blood and cerebrospinal fluid (CSF); however, its concentration in CSF is approximately twenty times lower than in plasma. It has been shown that several types of cells such as oligodendrocytes, neurons, and/or astrocytes contribute to the overall pool of pGSN in the CNS. Further, it has been postulated that pGSN plays multiple roles during microbial infection and modulates inflammatory responses; however, the exact mechanism of regulation is not known. We previously showed that levels of pGSN in CSF of individuals with advanced neurocognitive impairment due to HIV infection of the brain are decreased. Here, we show that macrophages express significant amounts of pGSN in response to HIV infection in vitro. Using immunohistochemistry of simian immunodeficiency virus infected rhesus monkey brains, we show that increased levels of pGSN are present in macrophage nodules creating locally a high level of this protein within the brain. This may not be reflected by the overall decreased level in the distinct CSF compartment.

Novel formulation and drug delivery strategies for the treatment of pediatric poverty-related diseases

INTRODUCTION

Due to a lack of approved drugs and formulations, children represent the most vulnerable patients. Magistral, unlicensed formulations obtained by the manipulation of solid forms should undergo clinical evaluation to ensure bioequivalence. The development of new pediatric medicines is complex and faces technological, economic and ethical challenges. This phenomenon has contributed to the emergence of an adult-children gap. To improve the situation, the World Health Organization launched the global campaign 'Make medicines child size' and a number of international initiatives have been established. The situation is more critical in the case of poverty-related diseases (PRDs) that mainly affect poor countries.

AREAS COVERED

This review critically discusses different strategies to develop pediatric formulations and drug delivery systems (DDS) in PRDs and their potential implementation in the current market. Readers will gain an updated perspective on the development of pediatric medicines for the treatment of PRDs and the proximate challenges and opportunities faced to ensure an effective pharmacotherapy.

EXPERT OPINION

There is an urgent need for the development of innovative, scalable and cost-viable formulations to ensure pediatric patients have access to appropriate medications for PRDs. The guidelines of the International Conference on Harmonisation constitute a very good orientation tool, as they emphasize physiological and developmental aspects that need to be considered in pediatric research. It is important to consider cultural, economic and ethical aspects that make developing nations facing PRDs different from the developed world. Thus, the best strategy would probably be to conceive and engage similar initiatives in the developing world, to address unattended therapeutic niches.

Modulatory effects of the CCR5 antagonist maraviroc on microglial pro-inflammatory activation elicited by gp120

Despite important clinical benefits of the highly active antiretroviral therapy, neurological disorders affect approximately 50% of AIDS patients. In the brain, infected microglia release pro-inflammatory mediators as well as human immunodeficiency virus type 1 (HIV-1) proteins, like the envelope protein gp120, that sustain inflammation and mediate neuronal damage. Gp120 allows the virus entry in the host cells via binding to the CD4 receptor together with a specific co-receptor (CCR5/CXCR4). The antiretroviral drug maraviroc is a CCR5 receptor antagonist, approved for the treatment of HIV-experienced patients. By interfering with a chemokine receptor, highly expressed in microglia, maraviroc has the potential to modulate their activation during HIV-1 infection. To test this hypothesis, primary cultures of rat cortical microglia were activated by gp120. Gp120(CN54) , a protein derived by macrophage (M)-tropic viruses, showed strong pro-inflammatory action, thus it was used to test the effects of maraviroc. The latter displayed opposite effects, depending on whether or not interferon-γ (IFNγ) was also present in the system. IFNγ significantly enhanced gp120 proinflammatory activity, possibly via up-regulation of CCR5 receptor expression. In this experimental paradigm, maraviroc significantly increased microglial activation, thus suggesting that its chronic use can exacerbate neuronal pathology, especially in HIV-experienced patients with higher cerebral IFNγ levels.

Current understanding of HIV-associated neurocognitive disorders pathogenesis

PURPOSE OF REVIEW

The present review discusses current concepts of HIV-associated neurocognitive disorders (HAND) in the era of antiretroviral therapy (ART). As the HIV epidemic enters its fourth decade (the second decade of ART), research must address evolving factors in HAND pathogenesis. These include persistent systemic and central nervous system (CNS) inflammation, aging in the HIV-infected brain, HIV subtype (clade) distribution, concomitant use of drugs of abuse, and potential neurotoxicity of ART drugs.

RECENT FINDINGS

Although the severest form of HAND, HIV-associated dementia (HAD), is now rare due to ART, the persistence of milder, functionally important HAND forms persist in up to half of HIV-infected individuals. HAND prevalence may be higher in areas of Africa where different HIV subtypes predominate, and ART regimens that are more effective in suppressing CNS HIV replication can improve neurological outcomes. HAND are correlated with persistent systemic and CNS inflammation, and enhanced neuronal injury due to stimulant abuse (cocaine and methamphetamine), aging, and possibly ART drugs themselves.

SUMMARY

Prevention and treatment of HAND requires strategies aimed at suppressing CNS HIV replication and effects of systemic and CNS inflammation in aging and substance-abusing HIV populations. Use of improved CNS-penetrating ART must be accompanied by evaluation of potential ART neurotoxicity.