Intrathecal viral replication and cerebral deficits in different stages of human immunodeficiency virus disease

Neuropathogenesis of human immunodeficiency virus infection

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain a common end-organ manifestation of viral infection. Subclinical and mild symptoms lead to neurocognitive and behavioral abnormalities. These are associated, in part, with viral penetrance and persistence in the central nervous system. Infections of peripheral blood monocytes, macrophages, and microglia are the primary drivers of neuroinflammation and neuronal impairments. While current antiretroviral therapy (ART) has reduced the incidence of HIV-associated dementia, milder forms of HAND continue. Depression, comorbid conditions such as infectious liver disease, drugs of abuse, antiretroviral drugs themselves, age-related neurodegenerative diseases, gastrointestinal maladies, and concurrent social and economic issues can make accurate diagnosis of HAND challenging. Increased life expectancy as a result of ART clearly creates this variety of comorbid conditions that often blur the link between the virus and disease. With the discovery of novel biomarkers, neuropsychologic testing, and imaging techniques to better diagnose HAND, the emergence of brain-penetrant ART, adjunctive therapies, longer life expectancy, and better understanding of disease pathogenesis, disease elimination is perhaps a realistic possibility. This review focuses on HIV-associated disease pathobiology with an eye towards changing trends in the face of widespread availability of ART.

Potential Pathways for CNS Drug Delivery Across the Blood-Cerebrospinal Fluid Barrier

The blood-brain interfaces restrict the cerebral bioavailability of pharmacological compounds. Various drug delivery strategies have been developed to improve drug penetration into the brain. Most strategies target the microvascular endothelium forming the blood-brain barrier proper. Targeting the blood-cerebrospinal fluid (CSF) barrier formed by the epithelium of the choroid plexuses in addition to the blood-brain barrier may offer added-value for the treatment of central nervous system diseases. For instance, targeting the CSF spaces, adjacent tissue, or the choroid plexuses themselves is of interest for the treatment of neuroinflammatory and infectious diseases, cerebral amyloid angiopathy, selected brain tumors, hydrocephalus or neurohumoral dysregulation. Selected CSF-borne materials seem to reach deep cerebral structures by mechanisms that need to be understood in the context of chronic CSF delivery. Drug delivery through both barriers can reduce CSF sink action towards parenchymal drugs. Finally, targeting the choroid plexus-CSF system can be especially relevant in the context of neonatal and pediatric diseases of the central nervous system. Transcytosis appears the most promising mechanism to target in order to improve drug delivery through brain barriers. The choroid plexus epithelium displays strong vesicular trafficking and secretory activities that deserve to be explored in the context of cerebral drug delivery. Folate transport and exosome release into the CSF, plasma protein transport, and various receptor-mediated endocytosis pathways may prove useful mechanisms to exploit for efficient drug delivery into the CSF. This calls for a clear evaluation of transcytosis mechanisms at the blood-CSF barrier, and a thorough evaluation of CSF drug delivery rates.

A brief and feasible paper-based method to screen for neurocognitive impairment in HIV-infected patients: the NEU screen

OBJECTIVE

Practical screening methods are necessary to detect neurocognitive impairment (NCI) in HIV-infected patients. We aimed to find a brief and feasible paper-based tool to facilitate the diagnosis of an HIV-associated neurocognitive disorder.

METHODS

A total of 106 HIV-infected outpatients with variable clinical characteristics were recruited in a multicenter investigation. NCI was diagnosed using a standardized neuropsychological tests battery (7 areas, 21 measures, ∼2 hours). Multiple score combinations were compared to find a paper-based method that took ≤10 minutes to apply. The presence of NCI was considered the gold standard for comparisons, and the sensitivity and specificity were calculated.

RESULTS

Subjects were mostly middle-aged (median, 44 years) men (87%) on antiretroviral treatment. NCI was detected in 51 individuals (48%) and was associated with lower nadir CD4 count (P < 0.001), receiving antiretroviral therapy (P = 0.004), fewer years of education (P = 0.009), and presence of comorbidities (P < 0.001). The score combination that showed the highest sensitivity (74.5%) and specificity (81.8%) detecting NCI included 3 measures of attention/working memory, executive functioning, and verbal fluency (part A of Trail Making Test, part B of Trail Making Test, and Controlled Oral Word Association Test scores). A broader paper-based selection of measures covering 7 areas indicated a sensitivity of 100% and a specificity of 96.3% (7 measures, ∼35 minutes).

CONCLUSIONS

The combination of the 3 measures presented in this study seems to be a rapid and feasible screening mean for NCI in HIV-infected patients. This approach, combined with screening for potential comorbidities and daily functioning interference, could help in the initial stages of a HIV-associated neurocognitive disorder diagnosis and in settings with limited access to neuropsychological resources.

Cognitive impairment in HIV infection is associated with MRI and CSF pattern of neurodegeneration

BACKGROUND AND PURPOSE

Biomarkers as indicators for the progression of human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain still elusive. We performed a cross-sectional study to analyze the correlation between cognitive impairment, abnormalities in magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) markers of neurodegeneration in HIV-infected patients.

METHODS

We enrolled 94 patients (82 men and 12 women; mean age 45 ± 10 years) with HIV infection, but without opportunistic infections of the CNS. All patients underwent MRI and CSF analysis. The global pattern of white matter signal intensity abnormalities, the index of atrophy, the severity of periventricular white matter abnormalities, and the severity of basal ganglia signal changes were analyzed. We measured CSF markers of neurodegeneration (total tau, phospho-tau, beta-amyloid). The findings of this evaluation were correlated with demographic and infection parameters of the patients in blood and CSF.

RESULTS

We found a highly significant correlation between the severity of global brain atrophy, basal ganglia signal changes, and cognitive impairment in HIV-infected patients. Furthermore, cognitive impairment was significantly correlated with total tau, but not with phospho-tau or A-beta-amyloid in CSF analysis.

CONCLUSIONS

Our results confirm the significant correlation between MRI changes and cognitive impairment in HIV infection. Furthermore, we could show that global brain atrophy and signal changes in basal ganglia are the typical MRI pattern in HAND. The correlation between cognitive impairment and total tau, but not phospho-tau, supports the hypothesis that HAND are not a subtype of Alzheimer's dementia.

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.

Entzündliche Erkrankungen

Unter einer Meningitis versteht man eine Entzündung von Pia mater und Arachnoidea. Das Erregerspektrum ist weit und reicht von Bakterien, die hämatogen-metastatisch, fortgeleitet oder durch offene Hirnverletzung zur eitrigen Meningitis führen, über Viren zu Pilzen und Parasiten. Insbesondere bei den unbehandelt häufig letal verlaufenden eitrigen Meningitiden ist eine rasche Diagnose mit Erregernachweis notwendig. Unverzüglich ist daraufhin eine spezifische, der regionalen Resistenzentwicklung angepasste Therapie einzuleiten. Die meningeale Affektion im Rahmen einer Listeriose oder Tuberkulose verdient aufgrund des klinischen Bildes, des Verlaufs und der spezifischen Therapie besondere Beachtung. Die fungalen Infektionen werden, da klinisch häufig als Meningoenzephalitis imponierend, in Abschn. 33.3 abgehandelt.

Interruptions of antiretroviral therapy in human immunodeficiency virus infection: are they detrimental to neurocognitive functioning?

Because interruptions of antiretroviral treatment may entail clinical risks for human immunodeficiency virus (HIV)-infected individuals, we investigated their impact on neurocognitive functioning. Cross-sectional study was carried out, comparing HIV-infected persons who had interrupted antiretroviral therapy in the past (interruption group, IG) with persons who had never discontinued therapy (noninterruption group, NIG). Interruption was defined as the discontinuation of highly active antiretroviral therapy (HAART) for more than 15 days after previous treatment of at least 15 days. All the participants were on therapy. Demographic, clinical, and neurocognitive variables were assessed. The primary end point was the percentage of people with neurocognitive impairment. The score in different neurocognitive domains was a secondary end point. A total of 83 subjects participated in the study (IG: n = 27; NIG: n = 56). Demographic and clinical characteristics were balanced between the groups, except for years since HIV diagnosis (IG, 13.8; NIG, 10.2 [P = .003]). The percentage of people with neurocognitive impairment was significantly higher in the IG group (IG, 59.25%; NIG, 33.92% [P = 0.02]). As for scores in neurocognitive domains, individuals in the IG showed worse neurocognitive functioning, and significant differences in attention/working memory and information processing speed were found. The adjusted analysis supported the unadjusted analysis. In this study, a higher prevalence of neurocognitive impairment was detected in HIV-infected persons who had interrupted antiretroviral therapy in the past. Additionally, neurocognitive functioning was observed to be more impaired in the same individuals. Further studies should examine the potential negative effects of antiretroviral therapy interruptions on neurocognitive functioning.

Measurement of soluble inflammatory mediators in cerebrospinal fluid of human immunodeficiency virus-positive patients at distinct stages of infection by solid-phase protein array

The objective of this study was to evaluate immune cytokine expression in cerebrospinal fluid (CSF) of patients with human immunodeficiency virus-1 (HIV-1)-associated dementia (HAD) using a novel cytokine array assay. HIV-1 induces a condition resembling classical subcortical dementia, known as HAD. The immune mechanisms contributing to HAD have not been elucidated. Cytokine expression in CSF was determined by solid-phase protein array in 33 neurologically asymptomatic HIV-positive male patients and were compared to levels in non-HIV controls and patients with HAD. Neurological examinations and lumbar and venous punctures were conducted in all patients and controls. Interleukin (IL)-1, IL-4, and IL-10, were up-regulated in all treated acquired immunodeficiency syndrome (AIDS) patients independent of neurological status compared to controls. In contrast, interferon gamma (IFN-gamma), IL-1alpha, IL-15, and tumor necrosis factor alpha (TNF-alpha) were highly expressed in patients with HAD compared to undemented HIV-positive patients. These results show that solid-phase protein array can detect immunological changes in patients infected with HIV. Cytokine expression levels differ in different disease stages and in patients on different treatment paradigms. Pending further validation on a larger number of patients, this method may be a useful tool in CSF diagnostics and the longitudinal evaluation of patient with HAD.

The Patient Cohort of the German Competence Network for HIV/AIDS (KompNet): a profile

OBJECTIVE

In this paper, we describe the main objectives, the study design and the onset of the patient cohort of the German Competence Network for HIV/AIDS (KompNet) (www.kompetenznetz-hiv.de). Furthermore, we depict sociodemographic and clinical baseline characteristics and an estimation of the coverage and representativity as to the composition of persons living with HIV/AIDS (PLWHA) in Germany.

METHODS

The KompNet cohort is an open, retrospective and prospective, multicenter, disease-specific and nationwide cohort study that started gathering data in June 2004. Semi-annually, follow up visits of the patients are documented, covering clinical and sociodemographic data. At enrolment and three years afterwards, an EDTA-sample is taken; a serum-sample is taken at every follow up visit.

RESULTS

As of 14.9.2008, a total of 15,541 patients were enrolled by 44 documenting sites. In September 2007, the cohort size was reduced to 10 outpatient clinics and fifteen private practitioners, covering a total of 9,410 patients. The documentation of these patients comprises 24,117 years of follow up-time since enrolment (mean: 2.6 years), 62,862 person years inclusive data documented retrospectively on course of HIV-infection and combined antiretroviral therapy (cART, mean: 6.7 years). 1,008 patients (10.7%) were lost to follow up and 175 (1.9%) died since enrolment. 84.9% of patients were men. Main risks of transmission were sex between men (MSM: 62.9%), heterosexual contacts (18.4%), intravenous drug use (IVDU: 7.0%) and origin from a high prevalence country (HPL: 5.2%). Mean age was 45 years.

CONCLUSION

The KompNet cohort covers about a quarter of all patients being under treatment in Germany. The composition of the cohort represents well the most important risks of transmission in Germany. The cohort contains a high proportion of patients being older than 49 years (28.1%). On basis of its comprehensive database and its biomaterials banks, the KompNet cohort serves as an important instrument to monitor and analyse the effects of combined antiretroviral therapy (cART) in Germany, interdigidating basis, clinical and psychosocial research in view to translational research.

[Highly active antiretroviral therapy of neuro-AIDS. Side effects on the nervous system and interactions]

Highly active antiretroviral therapy (HAART) has increased the mean survival time in the AIDS stage to sometimes more than 10 years. Five different groups of antiretroviral medications are known, of which integrase inhibitors and CCR5 antagonists represent the newest and most modern substances. The long AIDS survival time implies that side effects and interactions become relatively more important and must be differentiated from the symptoms of HIV itself. Side effects of HAART concern the central and peripheral nervous system and the muscles. The neurotoxicity of the components in HAART varies considerably and depends on the substance itself. Knowledge of side effects and interactions of HAART with antiepileptics, antidepressants, and analgetics are essential for the treatment of patients with neuro-AIDS.

Substantia nigra hyperechogenicity and CSF dopamine depletion in HIV

Dopaminergic dysfunction is thought to play a pivotal role in human immunodeficiency virus (HIV)-related dementia. Decreased dopamine (DA) levels in the cerebrospinal fluid (CSF) and neuronal loss in the substantia nigra (SN) have been reported in HIV-infected patients, suggesting nigrostriatal damage. Structural changes detectable as hyperechogenicity in transcranial ultrasound (TCS) scans of the SN have been reported in patients with Parkinson's disease (PD) and other neurological conditions. In this study, we assessed the echomorphology of the SN in 40 HIV-positive patients compared to 40 age- and sex-matched healthy controls and correlated these findings with CSF levels of DA and the metabolites homovanillic acid (HVA) and 3,4-dihydroxy phenylacetic acid (DOPAC) and with neuropsychologic performance. We observed that the SN of HIV-infected patients was hyperechogenic relative to that of controls (0.07 +/- 0.05 vs. 0.04 +/- 0.07 cm(2); mean +/- SEM; P < 0.001) and that this SN hyperechogenicity was correlated with decreased DA levels in the CSF, decreased CD4 cell count, and an impaired performance in the psychopathology assessment scale (AMDP) subtest for drive and psychomobility. An association to CDC stage, duration of HIV infection, or presence of HIV dementia was not observed. Our results indicate changes in the nigrostriatal system in HIV-infected patients that are detectable as hyperechogenic SN precede prominent extrapyramidal symptoms and cognitive dysfunction.

Nadir CD4 cell count predicts neurocognitive impairment in HIV-infected patients

Though antiretroviral therapy attenuates neurocognitive disruption, impairment is still observed. We studied the nadir CD4 cell count as a predictor of neurocognitive changes. This cross-sectional study assessed 64 HIV-infected patients in two groups: G1 (n = 26, nadir CD4 < or =200 cells/ml) and G2 (n = 38, nadir CD4 >200 cells/ml). Percentages of patients showing neurocognitive impairment were compared according to different nadir CD4 cutoffs (200, 250, 300, and 350 cells/ml). From G2, we also took the subgroup of patients receiving treatment (G3) and compared this group with G1, in which all patients were being treated. Demographic and clinical variables were evaluated, as were differences in neurocognitive function. Neurocognitive impairment tended to be more prevalent in G1 [19 patients (73.1%)] than in G2 [20 (52.6%), p = 0.123]. When nadir CD4 cutoffs were compared, there was a trend toward more impaired subjects as the CD4 nadir decreased. Significantly different functioning was found in attention/working memory (digit span backward, p = 0.032) and executive functions (trail making test, part B, p = 0.020), with better performance in G2. Comparison between G1 and G3 confirmed those findings. We found differences in neurocognitive functioning in relation to nadir CD4 count in HIV-infected patients. Attention should be given to this value in the management of neurocognitive protection in HIV infection.