Yoshiharu Miura

Tumor necrosis factor-related apoptosis-inducing ligand induces neuronal death in a murine model of HIV central nervous system infection

HIV-1 infection in the brain induces neuronal apoptosis leading to HIV-associated dementia. To explore the underlying mechanism, we developed a murine model by using human peripheral blood mononuclear cell (PBMC)–transplanted nonobese diabetic (NOD)–severe combined immunodeficiency (SCID) (hu-PBMC-NOD-SCID) mice. Administration of lipopolysaccharide (LPS) to HIV-1-infected hu-PBMC-NOD-SCID mice induced infiltration of HIV-1-infected human cells into the perivascular region of the brain and neuronal apoptosis was found in macrophage (M)-tropic but not T cell (T)-tropic HIV-1-infected brains. The apoptotic neurons were frequently colocalized with the HIV-1-infected macrophages that expressed tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL). Administration of a neutralizing antibody against human TRAIL but not human TNF-α or Fas ligand (FasL) blocked the neuronal apoptosis in the HIV-1-infected brain. These results strongly suggest a critical contribution of TRAIL expressed on HIV-1-infected macrophages to neuronal apoptosis.

A CD63 Mutant Inhibits T-cell Tropic Human Immunodeficiency Virus Type 1 Entry by Disrupting CXCR4 Trafficking to the Plasma Membrane

We have discovered that an N‐terminal deletion mutant of a membrane protein, CD63, (CD63ΔN) blocks entry of CXCR4‐using, T‐cell tropic human immunodeficiency virus type 1 (X4 HIV‐1) by suppressing CXCR4 surface expression. This suppression was observed for CXCR4 but not for CD4, CCR5, CD25, CD71 or other tetraspanin proteins. The suppression of CXCR4 expression on the plasma membrane appeared to be caused by mislocalization of CXCR4 and exclusive transportation of CXCR4 toward intracellular organelles, mainly late endosomes/lysosomes. Our data suggest that CXCR4 trafficking can be modified in terms of its recruitment to the plasma membrane without enhancing the degradation or arresting vesicular transport of CXCR4.

Human Immunodeficiency Virus Type 1 Vpr Inhibits Axonal Outgrowth through Induction of Mitochondrial Dysfunction

ABSTRACT Human immunodeficiency virus type 1 (HIV-1)-infected macrophages damage mature neurons in the brain, although their effect on neuronal development has not been clarified. In this study, we show that HIV-1-infected macrophages produce factors that impair the development of neuronal precursor cells and that soluble viral protein R (Vpr) is one of the factors that has the ability to suppress axonal growth. Cell biological analysis revealed that extracellularly administered recombinant Vpr (rVpr) clearly accumulated in mitochondria where a Vpr-binding protein adenine nucleotide translocator localizes and also decreased the mitochondrial membrane potential, which led to ATP synthesis. The depletion of ATP synthesis reduced the transportation of mitochondria within neurites. This mitochondrial dysfunction inhibited axonal growth even when the frequency of apoptosis was not significant. We also found that point mutations of arginine (R) residues to alanine (A) residues at positions 73, 77, and 80 rendered rVpr incapable of causing mitochondrial membrane depolarization and axonal growth inhibition. Moreover, the Vpr-induced inhibition was suppressed after treatment with a ubiquinone analogue (ubiquinone-10). Our results suggest that soluble Vpr is a major viral factor that causes a disturbance in neuronal development through the induction of mitochondrial dysfunction. Since ubiquinone-10 protects the neuronal plasticity in vitro, it may be a therapeutic agent that can offer defense against HIV-1-associated neurological disease.

A Novel Mutation in ELOVL4 Leading to Spinocerebellar Ataxia (SCA) With the Hot Cross Bun Sign but Lacking Erythrokeratodermia: A Broadened Spectrum of SCA34

IMPORTANCE Although mutations in 26 causative genes have been identified in the spinocerebellar ataxias (SCAs), the causative genes in a substantial number of families with SCA remain unidentified. OBJECTIVE To identify the causative gene of SCA in 2 Japanese families with distinct neurological symptoms and radiological presentations. DESIGN, SETTING, AND PARTICIPANTS Clinical genetic study at a referral center of 11 members from 2 Japanese families, which started in 1997. MAIN OUTCOMES AND MEASURES Results of neurological examinations and radiological evaluations. The causative mutation was identified using genome-wide linkage analysis and next-generation sequencing. RESULTS Affected members (9 of 11 members [81.8%]) showed slowly progressive cerebellar ataxia (all 9 members [100%]), ocular movement disturbance (all 9 members [100%]), and pyramidal tract signs (8 of 9 members [88.9%]) with an age at onset between the second and sixth decades of life. Besides cerebellar and pontine atrophy, magnetic resonance imaging of the brain revealed the hot cross bun sign (4 of 6 members [66.7%]), pontine midline linear hyperintensity (2 of 6 members [33.3%]), or high intensity in the middle cerebellar peduncle (1 of 6 members [16.7%]), which are all reminiscent of multiple system atrophy in tested patients. Using linkage analysis combined with exome and whole-genome sequencing, we identified a novel heterozygous mutation in the ELOVL fatty acid elongase 4 (ELOVL4) gene (c.736T>G, p.W246G) in both families. Haplotype analysis indicated that it was unlikely that these 2 Japanese families shared a common ancestor. Although a missense mutation in ELOVL4 (c.504G>C, p.L168F) was recently reported to be associated with SCA with erythrokeratodermia variabilis (SCA34) in a French-Canadian family, signs of erythrokeratodermia variabilis were absent in our families. CONCLUSIONS AND RELEVANCE Combined with the results of the family with SCA34 reported previously, this report confirms that mutations in ELOVL4 can cause dominantly inherited neurodegeneration severely affecting the cerebellum and brainstem. We should be aware that the presence of multiple system atrophy-like features on magnetic resonance imaging scans, together with cerebellar and brainstem atrophy, suggests SCA34, even when erythrokeratodermia variabilis is absent. The present study further broadened the spectrum of the clinical presentations of SCA34 associated with mutations in ELOVL4, which is involved in the biosynthesis of very long-chain fatty acids.

Characteristics of progressive multifocal leukoencephalopathy clarified through internet-assisted laboratory surveillance in Japan

BackgroundProgressive multifocal leukoencephalopathy (PML), a rare but fatal demyelinating disease caused by JC virus (JCV), occurs mainly in immunocompromised patients. As PML develops in individuals with various underlying disorders sporadically and infrequently, a nationwide survey of PML is difficult. This study was conducted to elucidate the characteristics of PML in Japan through an internet-assisted laboratory surveillance program.MethodsA diagnostic support system for PML was established using a real-time PCR assay of JCV DNA in cerebrospinal fluid (CSF), and requests for testing were received from clinicians via specialized websites. Medical histories of patients were collected through standardized questionnaires, and a database of CSF JCV loads and clinical information was created and analyzed.ResultsFor 4 years from April 2007 to March 2011, CSF specimens from 419 patients were tested. Forty-eight individuals were found positive for JCV DNA in their CSF and were diagnosed with PML. PML primarily occurred not only in HIV-positive patients (33.3%) but also in patients with hematologic disorders after receiving stem cell transplantation, chemotherapy, and/or immunosuppressive treatment (39.6%). The frequencies of PML cases among the subjects in these two categories were 20.3% and 23.5%, respectively. Although no significant features were observed with respect to CSF JCV loads in PML patients with an HIV infection or hematologic disorder, males were predominant in both groups (100% and 89.5%, respectively). The proportion of PML cases with autoimmune disorders (6.3%) or solid-organ transplants (2.1%) was smaller than those with HIV infection or hematologic disorders, probably due to the limited availability of therapeutic monoclonal antibodies and transplantation from brain dead donors.ConclusionsThe results suggest that the internet-assisted laboratory surveillance program might be a useful strategy for collecting precise real-time information on PML on a national level. The current database provides important background information for the diagnosis and treatment of patients with risk factors for PML.

Relationship between type 1 metabotropic glutamate receptors and cerebellar ataxia.

Imaging of type 1 metabotropic glutamate receptor (mGluR1) has recently become possible using positron emission tomography (PET). We aimed to examine the relationship between mGluR1 and cerebellar ataxia. Families with spinocerebellar ataxia type 19/22 (SCA19/22) and SCA6, six patients with sporadic SCA, and 26 healthy subjects underwent PET using an mGluR1 radiotracer. Volumes-of-interest were placed on the anterior and posterior lobes and vermis. The binding potential (BPND) was calculated to estimate mGluR1 availability. A partial volume correction was applied to the BPND values. The Scale for the Assessment and Rating of Ataxia (SARA) score were measured. In each patient with SCA19/22 and SCA6, the anterior lobe showed the highest decrease rates in the BPND values, compared with healthy subjects. In the families with SCA19/22 and SCA6, the disease durations and SARA scores were shorter and lower, respectively, in the offspring, compared with the parents. However, the offspring paradoxically showed lower BPND values, especially in the anterior lobe, compared with the parents. The patients with sporadic SCA showed significantly lower BPND values in all subregions than healthy subjects. The BPND values significantly correlated with the SARA scores in all participants. In conclusion, these results showed a decrease in mGluR1 availability in patients with hereditary and sporadic SCA, a correlation between mGluR1 availability and degree of cerebellar ataxia, and paradoxical findings in two families. These results suggest the potential use of mGluR1 imaging as a specific biomarker of cerebellar ataxia.

Small intestine CD4+ cell reduction and enteropathy in simian/human immunodeficiency virus KS661-infected rhesus macaques in the presence of low viral load

Human immunodeficiency virus type 1, simian immunodeficiency virus and simian/human immunodeficiency virus (SHIV) infection generally lead to death of the host accompanied by high viraemia and profound CD4(+) T-cell depletion. SHIV clone KS661-infected rhesus macaques with a high viral load set point (HVL) ultimately experience diarrhoea and wasting at 6-12 months after infection. In contrast, infected macaques with a low viral load set point (LVL) usually live asymptomatically throughout the observation period, and are therefore referred to as asymptomatic LVL (Asym LVL) macaques. Interestingly, some LVL macaques exhibit diarrhoea and wasting similar to the symptoms of HVL macaques and are termed symptomatic LVL (Sym LVL) macaques. This study tested the hypothesis that Sym LVL macaques have the same degree of intestinal abnormalities as HVL macaques. The proviral DNA loads in lymphoid tissue and the intestines of Sym LVL and Asym LVL macaques were comparable and all infected monkeys showed villous atrophy. Notably, the CD4(+) cell frequencies of lymphoid tissues and intestines in Sym LVL macaques were remarkably lower than those in Asym LVL and uninfected macaques. Furthermore, Sym LVL and HVL macaques exhibited an increased number of activated macrophages. In conclusion, intestinal disorders including CD4(+) cell reduction and abnormal immune activation can be observed in SHIV-KS661-infected macaques independent of virus replication levels.

Human immunodeficiency virus type‐1 vulnerates nascent neuronal cells

Macrophages or microglial cells are the major target cells for HIV‐1 infection in the brain. The infected cells release neurotoxic factors that may cause severe neuronal cell damage, especially in the basal ganglia and hippocampus. In this study, we used rat OHC to examine the region‐specific neuronal cell damage caused by HIV‐1‐infected macrophages. When OHC was cocultured with HIV‐1‐infected MDM, we found that neuronal cells at the GCL of the DG were preferentially killed via apoptosis, and that projection of MF from GCL to PCL of the CA3 region was severely disturbed. We marked precursor cells around the DG region by using an EGFP‐expressing retrovirus vector and found that these cells lost the ability to differentiate into neurons when exposed to HIV‐1‐infected MDM. In the DG, new neurons are normally incorporated into GCL or PCL, while in the presence of HIV‐1‐infected MDM, mature neurons failed to be incorporated into those layers. These data indicate that the neurotoxic factor(s) released from HIV‐1‐infected macrophages impede(s) neuronal cell repair in brain tissue. This suggests that DG is the region of the hippocampus most vulnerable to neuronal damage caused by HIV‐1 infection, and that its selective vulnerability is most likely due to the highly active neurogenesis that takes place in this region.

Decreased metabotropic glutamate receptor type 1 availability in a patient with spinocerebellar ataxia type 6: A 11C-ITMM PET study

OBJECTIVE Imaging of metabotropic glutamate receptor type 1 (mGluR1), localized exclusively in the cerebellar Purkinje cells and related to cerebellar function, has recently become possible using positron emission tomography (PET). We report the initial mGluR1 imaging in a 74-year-old woman with spinocerebellar ataxia type 6 (SCA6). METHODS The patient and 9 age-matched healthy controls underwent PET scanning with a mGluR1 radiotracer, N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl] -4-(11)C-methoxy-N-methylbenzamide. Volumes-of-interest were placed on the anterior and posterior lobes, vermis, and flocculus. Binding potential (BPND) was calculated to estimate mGluR1 availability using the simplified reference tissue model. A partial volume correction was applied to the BPND values. Additionally, the volume of the whole cerebellum was measured using MRI. RESULTS The corrected BPND values of the cerebellar subregions and the volume of the whole cerebellum in the patient were 51.0% to 68.3% and 72.6%, respectively, of the controls. Thus, the magnitude of reduced BPND values was relatively larger than the magnitude of cerebellar atrophy in the patient. CONCLUSION These findings suggest that the measurement of mGluR1 availability is more sensitive than morphological measurements by MRI to detect reduced cerebellar function. Thus, imaging of mGluR1, probably reflecting the number and distribution of Purkinje cells, can be a specific and sensitive marker for estimation of cerebellar function.

Alzheimer's Disease-Like Pattern of 18F-FDG Uptake during a Hyperglycemic State and Negative 11C-PiB Binding in a Patient with Mild Cognitive Impairment

Increased plasma glucose levels can cause the regional reduction of fluorine-18-labeled fluorodeoxyglucose (18F-FDG) uptake in the posterior cingulate, precuneus, and/or temporoparietal cortices as an Alzheimers disease (AD)-like pattern. However, the association of such an AD-like pattern of cerebral 18F-FDG uptake with AD pathophysiology is unknown. We report a case of a 70-year-old patient with mild cognitive impairment, and show that the AD-like pattern of cerebral 18F-FDG uptake during a hyperglycemic state could be reversible and is not associated with amyloid-β accumulation. Our case concludes that the AD-like pattern is dependent on the plasma glucose level and independent of AD pathophysiology.