Giant cell encephalitis and microglial infection with mucosally transmitted simian-human immunodeficiency virus SHIVSF162P3N in rhesus macaques

Neurocognitive disorders such as dementia and cognitive/motor impairments are among the most significant complications associated with human immunodeficiency virus (HIV) infection, especially in aging populations, yet the pathogenesis remains poorly understood. Activated macrophages and microglia in white matter along with the hallmark multinucleated giant cells are prominent features of HIV encephalitis (HIVE) and of several simian immunodeficiency virus (SIV) models. While infected microglia have been demonstrated in HIVE, this feature is not routinely seen in experimental infections in rhesus macaques using SIV or chimeric simian/HIV (SHIV) strains, limiting utility in HIV-1 pathogenesis and treatment studies. Here, 50 rhesus macaques were inoculated with the CCR5 (R5)-tropic SHIV_SF162P3N virus by one of three routes: intravenously (n?=?9), intrarectally (n?=?17), or intravaginally (n?=?24). Forty-three monkeys became viremic, 26 developed AIDS, and 7 (7/26, 27 %) developed giant cell SIV encephalitis (SIVE). Rapid progressor phenotype was evident in five of seven (71 %) macaques with SIVE, and expansion to utilize the CXCR4 coreceptor (X4 coreceptor switch) was observed in four out of seven (57 %). SIVE lesions were present in gray and white matter in the cerebrum, cerebellum, thalamus, and brain stem of affected animals. Lesions were composed of virally infected CD68⁺, CD163⁺, and HLA-DR⁺ macrophages accompanied by white matter damage, necrosis, and astroglial and microglial activation. Importantly, microglial infection was observed, which makes R5 SHIV_SF162P3N infection of macaques an attractive animal model not only to study transmission and HIVE pathogenesis but also to conduct preclinical evaluation of therapeutic interventions aimed at eradicating HIV-1 from the central nervous system (CNS).     

Investigations on four host response factors whose expression is enhanced in X4 SHIV encephalitis

HIV encephalopathy, one of the major complications of HIV infection, involves productive virus replication in macrophages in the brain in association with heightened expression of several host response factors. One or more of these factors are thought to be the cause of the degenerative changes in neurons in the brain. Macaques infected with SIV and SHIV viruses have provided excellent working models for studying mechanisms of the human disease. Although HIV encephalopathy is primarily associated with CCR5-utilizing viruses, our findings have shown that CXCR4-utilizing SHIVs were also capable of causing the syndrome in rhesus macaques. In SHIV-infected macaques, approximately 30% of the animals developed encephalitis. In order to understand the factors leading to end-stage encephalitis, we performed microarray analyses on brains of encephalitic and non-encephalitic-infected macaques, and found pronounced enhancement of expression of interleukin-4, platelet-derived growth factor-B chain, monocyte chemoattractant protein-1 and CXCL10 in the brains of the encephalitic animals. This review discusses the role of each of these factors in mediating SHIV encephalitis.     

Decrease of aquaporin‐4 and excitatory amino acid transporter‐2 indicate astrocyte dysfunction for pathogenesis of cortical degeneration in HIV‐associated neurocognitive disorders

Human immunodeficiency virus (HIV) encephalitis and degeneration of cerebral cortex are established histopathologies of HIV‐associated neurocognitive disorders (HAND). We previously reported decreased excitatory amino acid transporter‐2 (EAAT‐2) and astrocytic apoptosis in cortical degeneration using SIVmac239 and simian‐human immunodeficiency virus (SHIV)‐infected macaques and human AIDS autopsy cases. In the present study, we added highly pathogenic SIVsm543‐3‐infected macaques. These animals showed similar degenerative changes in the frontal cortex. Using 11 SIV‐infected macaques, three SIVsm543‐3, five SIVmac239 and three SHIV, we compared brain pathology caused by three different viruses and further analyzed the pathogenic process of HAND. We noticed vacuolar changes in perivascular processes of astrocytes by electron microscopy, and examined expression of astrocyte‐specific protein aquaporin‐4 (AQP4) by immunohistochemistry. APQ4 was diffusely positive in the neuropil and perivascular area in control brains. There was patchy or diffuse decrease of AQP4 staining in the neuropil of SIV‐infected macaques, which was associated with EAAT‐2 staining by double immunostaining. A quantitative analysis demonstrated significant positive correlation between areas of AQP4 and EAAT‐2. Some astrocytes express EAAT‐2 but not AQP4, and decrease of EAAT‐2 expression tended to be less than the decrease of AQP4. Active‐caspase‐3 immunostaining demonstrated apoptosis of neurons and astrocytes in the area of AQP4/EAAT‐2 reduction. These results suggest that AQP4 is damaged first and decrease of EAAT‐2 may follow in pathogenesis of cortical degeneration. This is the first demonstration of decrease of AQP4 and its association with EAAT‐2 decrease in AIDS brain, suggesting a role in the pathogenesis of HAND.     

Monocyte/macrophage trafficking in acquired immunodeficiency syndrome encephalitis: Lessons from human and nonhuman primate studies

Here the authors discuss evidence in human and animal models supporting two opposing views regarding the pathogenesis of human immunodeficiency virus (HIV) in the central nervous system (CNS): (1) HIV infection in the CNS is a compartmentalized infection, with the virus-infected macrophages entering the CNS early, infecting resident microglia and astrocytes, and achieving a state of latency with evolution toward a fulminant CNS infection late in the course of disease; or alternatively, (2) events in the periphery lead to altered monocyte/macrophage (MΦ) homeostasis, with increased CNS invasion of infected and/or uninfected MΦs. Here the authors have reevaluated evidence presented in the favor of the latter model, with a discussion of phenotypic characteristics distinguishing normal resident microglia with those accumulating in HIV encephalitis (HIVE). CD163 is normally expressed by perivascular MΦs but not resident microglia in normal CNS of humans and rhesus macaques. In agreement with other studies, the authors demonstrate expression of CD163 by brain MΦs in HIVE and simian immunodeficiency virus encephalitis (SIVE). CNS tissues from HIV-sero positive individuals with HIVE or HIV-associated progressive multifocal leukoencephalopathy (PML) were also examined. In HIVE, the authors further demonstrate colocalization of CD163 and CD16 (FcγIII recptor) gene expression, the latter marker associated with HIV infection of monocyte in vivo and permissivity of infection. Indeed, CD163⁺ MΦs and microglia are often productively infected in HIVE CNS. In SIV infected rhesus macaques, CD163⁺ cells accumulate perivascularly, within nodular lesions and the parenchyma in animals with encephalitis. Likewise, parenchymal microglia and perivascular MΦs are CD163⁺ in HIVE. In contrast to HIVE, CD163⁺ perivascular and parenchymal MΦs in HIV-associated PML were only associated with areas of demyelinating lesions. Interestingly, SIV-infected rhesus macaques whose viral burden was predominantly at 1 × 10⁶ copies/ml or greater developed encephalitis. To further investigate the relationship between CD163⁺/CD16⁺ MΦs/microglia in the CNS and altered homeostasis in the periphery, the authors performed flow-cytometric analyses of peripheral blood mononuclear cells (PBMCs) from SIV-infected rhesus macaques. The results demonstrate an increase in the percent frequency of CD163⁺/CD16⁺ monocytes in animals with detectable virus that correlated significantly with increased viral burden and CD4⁺ T-cell decline. These results suggest the importance of this monocyte subset in HIV/SIV CNS disease, and also in the immune pathogenesis of lentiviral infection. The authors further discuss the potential role of CD163⁺/CD16⁺ monocyte/MΦ subset expansion, altered myeloid homeostasis, and potential consequences for immune polarization and suppression. The results and discussion here suggest new avenues for the development of acquired immunodeficiency syndrome (AIDS) therapeutics and vaccine design.     

Estrogen receptor beta (ERbeta) mRNA and protein in serotonin neurons of macaques.

This study used double in situ hybridization (ISH) to examine the colocalization of estrogen receptor beta (ERbeta) mRNA in serotonin neurons of rhesus macaques (Macaca mulatta). In addition, immunocytochemistry (ICC) was used to examine the expression and regulation of ERbeta protein in raphe neurons of the macaque midbrain. For double ISH, monkey specific riboprobes for ERbeta incorporating radiolabeled-UTP and a riboprobe for the human serotonin reuptake transporter (SERT) incorporating digoxigenin were applied to midbrain sections from spayed rhesus macaques. ERbeta mRNA hybridization signal was expressed in most cells containing SERT mRNA in the dorsal and median raphe and pons. There were also non-SERT neurons expressing ERbeta mRNA. In addition, ERbeta protein was detected with an affinity purified polyclonal antibody generated against a synthetic peptide corresponding to the D domain of human ERbeta conjugated to bovine serum albumin (provided by Dr. Philippa Saunders, MRC, Edinburgh). Midbrain sections containing the dorsal raphe from spayed rhesus macaques with and without hormone replacement therapy were processed for ERbeta immunostaining. ERbeta protein was detected at a similar intensity and in a similar number of cells in the dorsal raphe neurons in all treatment groups. Thus, the expression of ERbeta protein in the dorsal raphe was consistent with the expression of ERbeta mRNA. In conclusion, ERbeta mRNA is expressed by serotonin neurons and it is translated to protein. ERbeta protein, like ERbeta mRNA, is detected at similar levels in the presence or absence of ovarian hormones.     

Effects of genetic and early environmental risk factors for depression on serotonin transporter expression and methylation profiles

The serotonin transporter (SERT) gene-linked polymorphic region (5-HTTLPR) has been implicated in moderating the link between life stress and depression. However, respective molecular pathways of gene–environment (GxE) interaction are largely unknown. Sustained alterations in SERT gene expression profiles, possibly mediated by epigenetic modifications, are a frequent correlate of depression and may thus constitute a putative mediator of GxE interaction. Here, we aimed to investigate joint effects of 5-HTTLPR and self-reported environmental adversity throughout the lifespan (prenatal, early and recent stress/trauma) on in vivo SERT mRNA expression in peripheral blood cells. To further evaluate whether environmentally induced changes in SERT expression are mediated by epigenetic modifications, we analyzed 83 CpG sites within a 799-bp promoter-associated CpG island of the SERT gene using the highly sensitive method of bisulfite pyrosequencing. Participants were 133 healthy young adults. Our findings show that both the 5-HTTLPR S allele and maternal prenatal stress/child maltreatment are associated with reduced in vivo SERT mRNA expression in an additive manner. Remarkably, individuals carrying both the genetic and the environmental risk factors exhibited 32.8% (prenatal stress) and 56.3% (child maltreatment) lower SERT mRNA levels compared with those without any risk factor. Our data further indicated that changes in SERT mRNA levels were unlikely to be mediated by DNA methylation profiles within the SERT CpG island. It is thus conceivable that the persistent changes in SERT expression may in turn relate to altered serotonergic functioning and possibly convey differential disease vulnerability associated with 5-HTTLPR and early adversity.     

Detection of the human immunodeficiency virus regulatory protein tat in CNS tissues

Neuropathologically, human immunodeficiency virus (HIV) is associated with a range of inflammatory disorders, extensive cortical neuronal loss, and dendritic and synaptic damage. Although the mechanisms resulting in these abnormalities are still unclear, the neurotoxic effects are thought to be due in part to viral products including the tat gene product. We have previously shown that Tat when presented to neurons extracellularly interacts with neuronal cell membranes to cause neuronal excitation and toxicity in fmole amounts. To determine the role of Tat in mediating HIV encephalitis (HIVE), we detected tat mRNA and protein in tissue extracts of nine patients with HIVE and seven patients without HIVE. Despite long autopsy times and significant degradation, tat mRNA was detected in 4/9 patients with HIVE but not in any of the seven patients without dementia. Similarly, the env mRNA was also detected in 5/9 patients with HIVE but not in the patients without HIVE. However, vif mRNA was detected in both groups of patients with (5/9) or without (2/7) HIVE. Using protein extracts from the brains of the same groups of patients we were unable to detect Tat by enzyme linked immunosorbant assay (ELISA) (sensitivity of 2 ng Tat/ml of brain tissue). However, Tat could be detected immunohistochemically and in protein extracts from the brains of rhesus macaques with encephalitis due to a chimeric strain of HIV and simian immunodeficiency virus (SHIV). Our observations support the role of Tat in the neuropathogenesis of HIV and SHIV encephalitis.     

Dopamine deficits and regulation of the cAMP second messenger system in brains of simian immunodeficiency virus-infected rhesus monkeys

The basal ganglia, structures rich in the neurotransmitter dopamine, are primarily affected during human immunodeficiency virus (HIV) infection. The authors measured levels of dopamine and its metabolites, homovanillic acid and 3,4-dihydroxyphenylacetic acid, in brains of uninfected and simian immunodeficiency virus (SIV)-infected rhesus monkeys during the asymptomatic stage of the infection. Moreover, the authors investigated changes in cyclic adenosine monophosphate (cAMP) and cAMP response element-binding protein (CREB), two factors involved in the signaling pathway of dopamine. The brain regions examined were the nucleus accumbens and the corpus amygdaloideum, which are limbic structures of the basal ganglia that are involved in the pathophysiology of psychiatric disorders and substance abuse. Dopamine content was reduced in both regions of SIV-infected monkeys compared to uninfected animals. Moreover, dopamine deficits were associated with a decrease in expression of total CREB. Intracellular concentrations of cAMP were decreased in nucleus accumbens and remained unchanged in corpus amygdaloideum of SIV-infected macaques. Changes in dopamine signaling were not related to pathology or viral load of the investigated animals.The results suggest that dopamine defects precede neurologic deficits and implicate dysfunction of the dopaminergic system in the etiopathogenesis of HIV dementia. Therefore, affective complications in HIV subjects should not be interpreted only as reactive psychological changes. The alterations in the mesolimbic dopaminergic system during asymptomatic stage of SIV infection implicate a biological background for psychiatric disorders in HIV infection.     

Functional cortical effects of novel allelic variants of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) in humans

INTRODUCTION: Genetic variations of the serotonin transporter-linked polymorphic region (5-HTTLPR) have been implicated in the pathogenesis of several psychiatric disorders. Recent evidence indicates that the biallelic polymorphic region (S and L allele) contains additional variations affecting the mRNA expression. METHODS: According to recent preclinical and clinical studies, the loudness dependence of auditory evoked potentials (LD) was investigated as surrogate parameter for the central serotonergic activity in 185 healthy subjects subdivided according to newly identified 5-HTTLPR genotypes. RESULTS: Individuals homozygous for the L (A) allele showed the lowest LD of all genotypes suggesting a high serotonergic neurotransmission. The other observed genotypes (L (A)/L (G), S/L (A), S/L (G), S/S) had an LD which was similar to each other but higher compared to the L (A)/L (A) genotype. DISCUSSION: The data provide a rationale to subdivide the L allele of the 5-HTTLPR into L (A) and L (G) alleles in terms of their serotonin activity as indicated by the LD. The present IN VIVO measurements provide a basis for grouping the L (G) and S alleles for further investigations.     

Psychopharmacotherapy of psychiatric syndromes in asymptomatic and symptomatic HIV infection

It is evident that human immunodeficiency virus (HIV) infection is one of the most serious public health issues in decades. HIV infection compromises cell-mediated immunity which ultimately may result in the acquired immunodeficiency syndrome (AIDS). AIDS, to date, remains an incurable and progressively fatal disorder. HIV infection is spreading beyond the originally identified high-prevalence groups of gay/bisexual males, intravenous drug abusers, and recipients of infected blood or blood products. Today, more and more heterosexual males, women, adolescents, and children have been infected with this lethal virus. This report addresses some of the psychiatric complications associated with HIV infection and discusses the diagnostic and clinical management challenges that clinicians must face as they deal with the increasing population of HIV-infected patients. Depression, anxiety, psychosis, delirium, and dementia are commonly encountered disorders associated with HIV spectrum disorders which must be accurately identified and can be effectively managed with psychopharmacological interventions.     

HIV-Patienten mit psychiatrischen Krankheiten Behandlungsstrategien und Medikamenteninteraktionen

Since the beginning of the endemic phase of the human immunodeficiency virus (HIV), about 60,000 humans have been infected in Germany by this retrovirus. Epidemiological data indicate approximately 2,500 new infections annually. Due to the multiagent antiviral therapy available, only about 600 cases progressed to the clinical picture of full-blown acquired immunodeficiency syndrome (AIDS) in 1999. [Robert-Koch-Institut (Berlin), http://www.rki.de] If an HIV infection or AIDS is current, a higher prevalence of psychiatric disorders in these persons can be anticipated. Psychoactive drugs and their dosages need to be chosen under several considerations and with regard to the HIV infection, since interactions between antiviral and psychotropic drugs occur frequently. The use of psychotropic drugs is often required and thus cannot be ignored. Therefore, psychiatric disorders, medical treatment strategies, interactions between psychotropic and antiretroviral drugs, and biotransformation mechanisms are discussed with regard to an underlying HIV infection.     

Relationships between serotonin transporter promoter polymorphism, platelet serotonin transporter binding and clinical phenotype in suicidal and non-suicidal adolescent inpatients

Summary. Relationships between the serotonin transporter promoter polymorphism (5-HTTLPR), platelet serotonin transporter (SERT) binding and clinical phenotype were examined in 32 suicidal and 28 non-suicidal Ashkenazi Israeli adolescent psychiatric inpatients. The 5-HTTLPR polymorphism was not associated with transporter binding or with suicidality or other clinical phenotypes. However, in the suicidal group, a significant positive correlation between platelet SERT density and anger scores (n=32, r=.40; p=.027) and a negative correlation between platelet count and trait anxiety (n=32, r=–.42; p=.034) were observed.     

Effects of oral estrogen, raloxifene and arzoxifene on gene expression in serotonin neurons of macaques

The serotonin neural system contributes to cognition and affect, both of which exhibit pathologies with gender bias. We previously showed that estrogen (E) treatment of female macaques via Silastic implant alters gene expression for tryptophan hydroxylase (TPH), the serotonin reuptake transporter (SERT) and the 5HT1A autoreceptor. In addition, we have found that serotonin neurons of macaques express ER beta (ER beta). Together these studies suggest that the serotonin neural system could transduce the action of estrogen via ER beta on aspects of mood and cognition. However, estrogen replacement therapy can increase the risk for breast and uterine cancer. Therefore, we questioned whether the selective estrogen receptor modulators, raloxifene and arzoxifene, act in a manner similar to E on gene expression in serotonin neurons of a nonhuman primate model. Female rhesus macaques were ovariectomized and orally dosed with vehicle, estradiol 17beta, raloxifene or arzoxifene once per day by sipper bottles for 30 days. The animals were then euthanized and the midbrains were prepared for in situ hybridization for TPH, SERT and 5HT1A receptor mRNAs followed by densitometric analysis. There was a significant increase in TPH total signal (positive pixelsxOD) with E, raloxifene and arzoxifene, respectively. There was a significant decrease in SERT mRNA optical density with all treatments. 5HT1A autoreceptor mRNA did not change with any treatment. If these changes in gene expression are reflected by similar changes in the functional proteins, then raloxifene or arzoxifene could increase serotonin neurotransmission with little or no negative action in peripheral tissues. In conclusion, the selective estrogen receptor modulators, raloxifene and arzoxifene, act in a manner similar to natural E on TPH and SERT mRNA expression in serotonin neurons. This suggests that raloxifene and arzoxifene are agonists at ER beta in the context of the serotonin neuron. However, the responses to E were more variable and less robust with the oral dosing paradigm compared to a chronic implant paradigm.     

In vivo characterization of macrophage-tropic simian immunodeficiency virus molecular clones in rhesus macaques

Macrophages are a major target of HIV/SIV infection and play an important role in pathogenesis by serving as viral reservoirs in the central nervous system. Previously, a unique early SIVmac251 envelope (Env) variant, deSIV147 was cloned from blood of a rhesus macaque with rapid disease progression and SIV-associated encephalitis. Here, we show that infectious molecular clone deSIV147 caused systemic infection in rhesus macaques following intravenous or intrarectal exposure. Next, we inoculated deSIV147 into macaques depleted of CD4+ T cells and found that animals were SIV-positive, with high plasma and CSF viral loads. These macaques also showed SIVp17-positive macrophages in brain, lymph nodes, colon, lung, and liver. Furthermore, accumulation of perivascular macrophages, multinucleated giant cells, and microgliosis was detected. These findings suggest that the neurotropic deSIV147 clone will be useful to study macrophage infection in HIV/SIV-associated neurocognitive disorders, gain insights into myeloid cell reservoirs in brain and other anatomical sites, as well as test strategies for eradication.     

Diagnosis and treatment of substance use disorders in patients with HIV infection

Drug users infected with the human immunodeficiency virus (HIV) are a rapidly growing group of patients whose optimal medical and psychiatric care requires that the substance use disorders are assessed and treated. Drug users have high rates of other psychiatric disorders even in the absence of HIV infection. The effects of acute and chronic drug use complicate the assessment of psychiatric symptoms. There is evidence that in the early stages of HIV disease, drug use plays a larger role in producing psychiatric disorders than does HIV itself. In general, neuropsychiatric problems do not appear to progress more rapidly in drug users than in HIV infected homosexual men. However, compliance with and adherence to medical care are major problems in the treatment of drug users. The combined treatment of substance use and psychiatric disorders may improve the likelihood that patients will receive adequate medical treatment of HIV disease, particularly if integrated systems of care are in place.     

Simian immunodeficiency virus mac251 infection of astrocytes

Human immunodeficiency virus type 1 (HIV-1) infection of astrocytes has been demonstrated in the brains of patients with AIDS dementia complex (ADC) and may play an important role in neuropathological pathways of HIV-related encephalopathy. SIVmac-infected monkeys develop an acquired immunodeficiency syndrome (AIDS) with CNS involvement which is quite similar to that seen in human AIDS. We investigated the in vitro infection of primary astrocytes derived from adult macaques with SIVmac251 or an isogenic virus that expresses a non-functional Nef protein (SIVmac251-DeltaNef). In both cases we observed that viral expression was mostly limited to early regulatory genes after a transient phase of late viral gene expression (i.e. env and gag), as reported for HIV-1-infected astrocytes in vivo. Late viral gene expression could be reactivated by TNF-alpha, GM-CSF and IFN-gamma treatment of SIVmac251-infected astrocytes but not by similarly treated SIVmac251-DeltaNef-infected cells. Our findings suggest that Nef is not involved in the restricted expression of SIV in astrocytes, but may be important for astrocytes to function as a viral reservoir in the CNS. In additional experiments, we demonstrated Rev and Nef expression in 17 of 27 primary astrocyte cultures derived from macaques infected by SIVmac251. Nef was located in the cytoplasm of astrocytes infected by SIVmac251 in vivo, but displayed perinuclear localisation after infection in vitro. Attempts to activate late viral gene expression by astrocytes infected in vivo using cytokines or by coculture with human cord blood mononuclear cells were unsuccessful.     

Neuropsychiatric aspects of human immunodeficiency virus (HIV) infection

Human immunodeficiency virus (HIV) infection with central nervous system (CNS) involvement causes a variety of psychiatric complications among a significant proportion of infected individuals. A cure for the fully developed AIDS related to HIV infection remains elusive, and HIV/AIDS is a leading cause of death among adults between the ages of 25 and 44. Life expectancy, however, has gradually increased over the years, resulting in a concern for a potential increase in the incidence of secondary psychiatric manifestations. Knowledge of the neuropathology of HIV-CNS dysfunction and familiarity with its clinical presentation can aid clinicians in a determination of the appropriate therapy inclusive of psychiatric care that may be useful for a specific individual in their treatment.