Jochen Klucken

The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease.

Tangier disease (TD) is an autosomal recessive disorder of lipid metabolism. It is characterized by absence of plasma high-density lipoprotein (HDL) and deposition of cholesteryl esters in the reticulo-endothelial system with splenomegaly and enlargement of tonsils and lymph nodes. Although low HDL cholesterol is associated with an increased risk for coronary artery disease, this condition is not consistently found in TD pedigrees. Metabolic studies in TD patients have revealed a rapid catabolism of HDL and its precursors. In contrast to normal mononuclear phagocytes (MNP), MNP from TD individuals degrade internalized HDL in unusual lysosomes, indicating a defect in cellular lipid metabolism. HDL-mediated cholesterol efflux and intracellular lipid trafficking and turnover are abnormal in TD fibroblasts, which have a reduced in vitro growth rate. The TD locus has been mapped to chromosome 9q31 (ref. 9). Here we present evidence that TD is caused by mutations in ABC1, encoding a member of the ATP-binding cassette (ABC) transporter family, located on chromosome 9q22–31 (ref. 10). We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product. The identification of ABC1 as the TD locus has implications for the understanding of cellular HDL metabolism and reverse cholesterol transport, and its association with premature cardiovascular disease.

Regulation of scavenger receptor CD163 expression in human monocytes and macrophages by pro- and antiinflammatory stimuli.

CD163, also referred to as M130, a member of the scavenger receptor cysteine‐rich family (SRCR) is exclusively expressed on cells of the monocyte lineage. In freshly isolated monocytes the CD14bight CD16+ monocyte subset revealed the highest expression of CD163 among all monocyte subsets. CD163 mRNA and protein expression is up‐regulated during macrophage colony‐stimulating factor (M‐CSF)‐dependent phagocytic differentiation of human blood monocytes. In contrast, monocytic cells treated with GM‐CSF and interleukin‐4 (IL‐4) for dendritic differentiation down‐regulate this antigen. CD163 expression is also suppressed by proinflammatory mediators like lipopolysaccharide (LPS), interferon‐γ (IFN‐γ), and tumor necrosis factor α, whereas IL‐6 and the antiinflammatory cytokine interleukin‐10 (IL‐10) strongly up‐regulate CD163 mRNA in monocytes and macrophages. The effects of the immunosuppressants dexamethasone, cyclosporin A (CA), and cortisol differ in their capacity to influence CD163 mRNA levels. Our results demonstrate that CD163 expression in monocytes/macrophages is regulated by proinflammatory and antiinflammatory mediators. This expression pattern implies a functional role of CD163 in the antiinflammatory response of monocytes. J. Leukoc. Biol. 67: 97–103; 2000.

The Co-chaperone Carboxyl Terminus of Hsp70-interacting Protein (CHIP) Mediates α-Synuclein Degradation Decisions between Proteasomal and Lysosomal Pathways

α-Synuclein is a major component of Lewy bodies, the pathological hallmark of Parkinson disease, dementia with Lewy bodies, and related disorders. Misfolding and aggregation of α-synuclein is thought to be a critical cofactor in the pathogenesis of certain neurodegenerative diseases. In the current study, we investigate the role of the carboxyl terminus of Hsp70-interacting protein (CHIP) in α-synuclein aggregation. We demonstrate that CHIP is a component of Lewy bodies in the human brain, where it colocalizes with α-synuclein and Hsp70. In a cell culture model, endogenous CHIP colocalizes with α-synuclein and Hsp70 in intracellular inclusions, and overexpression of CHIP inhibits α-synuclein inclusion formation and reduces α-synuclein protein levels. We demonstrate that CHIP can mediate α-synuclein degradation by two discrete mechanisms that can be dissected using deletion mutants; the tetratricopeptide repeat domain is critical for proteasomal degradation, whereas the U-box domain is sufficient to direct α-synuclein toward the lysosomal degradation pathway. Furthermore, α-synuclein, synphilin-1, and Hsp70 all coimmunoprecipitate with CHIP, raising the possibility of a direct α-synuclein-CHIP interaction. The fact that the tetratricopeptide repeat domain is required for the effects of CHIP on α-synuclein inclusion morphology, number of inclusions, and proteasomal degradation as well as the direct interaction of CHIP with Hsp70 implicates a cooperation of CHIP and Hsp70 in these processes. Taken together, these data suggest that CHIP acts a molecular switch between proteasomal and lysosomal degradation pathways.

High efficacy of clonal growth and expansion of adult neural stem cells.

Neural stem cells (NSCs) from the adult central nervous system are currently being investigated for their potential use in autologous cell replacement strategies. High expansion rates of NSCs in culture are crucial for the generation of a sufficient amount of cells needed for transplantation. Here, we describe efficient growth of adult NSCs in Neurobasal medium containing B27 supplement under clonal and low-density conditions in the absence of serum or conditioned medium. Expansion of up to 15-fold within 1 week was achieved on low-density NSC cultures derived from the lateral ventricle wall, the hippocampal formation, and the spinal cord of adult rats. A 27% single-cell cloning efficiency in Neurobasal/B27 combination further demonstrates its growth-promoting ability. Multipotency and nontumorgenicity of NSCs were retained despite the high rate of culture expansion. In addition, increased cell survival was obtained when Accutase, instead of trypsin, was used for enzymatic dissociation of NSC cultures. This work provides an important step toward the development of standardized protocols for highly efficient in vitro expansion of NSCs from the adult central nervous system to move more closely to the clinical use of NSCs.

Dopaminergic neuron loss and up-regulation of chaperone protein mRNA induced by targeted over-expression of alpha-synuclein in mouse substantia nigra

Several transgenic mouse lines with altered α‐synuclein expression have been developed that show a variety of Parkinson’s disease‐like symptoms without specific loss of dopaminergic neurons. Targeted over‐expression of human α‐synuclein using viral‐vector mediated gene delivery into the substantia nigra of rats and non‐human primates leads to dopaminergic cell loss and the formation of α‐synuclein aggregates reminiscent of Lewy bodies. In the context of these recent findings, we used adeno‐associated virus (AAV) to over‐express wild type human α‐synuclein in the substantia nigra of mice. We hypothesized that this over‐expression would recapitulate pathological hallmarks of Parkinson’s disease, creating a mouse model to further characterize the disease pathogenesis. Recombinant AAV expressing α‐synuclein was stereotaxically injected into the substantia nigra of mice, leading to a 25% reduction of dopaminergic neurons after 24 weeks of transduction. Furthermore, examination of mRNA levels of stress‐related proteins using laser capture microdissection and quantitative PCR revealed a positive correlation of Hsp27 expression with the extent of viral transduction at 4 weeks and a positive correlation of Hsp40, Hsp70 and caspase 9 with the extent of viral transduction at 24 weeks. Taken together, our findings suggest that targeted over‐expression of α‐synuclein can induce pathology at the gross anatomical and molecular level in the substantia nigra, providing a mouse model in which upstream changes in Parkinson’s disease pathogenesis can be further elucidated.

Dopamine receptor activation promotes adult neurogenesis in an acute Parkinson model.

Cell proliferation of neural progenitors in the subventricular zone (SVZ) of Parkinson disease (PD) patients and animal models is decreased. It was previously demonstrated that the neurotransmitter dopamine modulates cell proliferation in the embryonic brain. The aim of the present study was to analyze whether oral treatment with the dopamine receptor agonist pramipexole (PPX) modulates adult neurogenesis in the SVZ/olfactory bulb system in a dopaminergic lesion model. 6-Hydroxydopamine (6-OHDA) lesioned adult rats received either PPX (1.0 mg/kg) or PBS orally twice daily and bromodeoxyuridine (BrdU, a cell proliferation marker) for 10 days and were perfused immediately after treatment or 4 weeks after PPX withdrawal. Stereological analysis revealed a significant augmentation in SVZ proliferation by PPX. Consecutively, enhanced neuronal differentiation and more new neurons were present in the olfactory bulb 4 weeks after PPX withdrawal. In addition, dopaminergic neurogenesis was increased in the olfactory bulb after PPX treatment. Motor activity as assessed by using an open field paradigm was permanently increased even after long term PPX withdrawal. In addition, we demonstrate that D2 and D3 receptors are present on adult rat SVZ-derived neural progenitors in vitro, and PPX specifically increased mRNA levels of epidermal growth factor receptor (EGF-R) and paired box gene 6 (Pax6). Oral PPX treatment selectively increases adult neurogenesis in the SVZ-olfactory bulb system by increasing proliferation and cell survival of newly generated neurons. Analyzing the neurogenic fate decisions mediated by D2/D3 signaling pathways may lead to new avenues to induce neural repair in the adult brain.

Unbiased and mobile gait analysis detects motor impairment in Parkinson's disease.

Motor impairments are the prerequisite for the diagnosis in Parkinsons disease (PD). The cardinal symptoms (bradykinesia, rigor, tremor, and postural instability) are used for disease staging and assessment of progression. They serve as primary outcome measures for clinical studies aiming at symptomatic and disease modifying interventions. One major caveat of clinical scores such as the Unified Parkinson Disease Rating Scale (UPDRS) or Hoehn&Yahr (H&Y) staging is its rater and time-of-assessment dependency. Thus, we aimed to objectively and automatically classify specific stages and motor signs in PD using a mobile, biosensor based Embedded Gait Analysis using Intelligent Technology (eGaIT). eGaIT consist of accelerometers and gyroscopes attached to shoes that record motion signals during standardized gait and leg function. From sensor signals 694 features were calculated and pattern recognition algorithms were applied to classify PD, H&Y stages, and motor signs correlating to the UPDRS-III motor score in a training cohort of 50 PD patients and 42 age matched controls. Classification results were confirmed in a second independent validation cohort (42 patients, 39 controls). eGaIT was able to successfully distinguish PD patients from controls with an overall classification rate of 81%. Classification accuracy increased with higher levels of motor impairment (91% for more severely affected patients) or more advanced stages of PD (91% for H&Y III patients compared to controls), supporting the PD-specific type of analysis by eGaIT. In addition, eGaIT was able to classify different H&Y stages, or different levels of motor impairment (UPDRS-III). In conclusion, eGaIT as an unbiased, mobile, and automated assessment tool is able to identify PD patients and characterize their motor impairment. It may serve as a complementary mean for the daily clinical workup and support therapeutic decisions throughout the course of the disease.

Decreased levels of BDNF protein in Alzheimer temporal cortex are independent of BDNF polymorphisms.

Levels of brain-derived neurotrophic factor (BDNF) are reduced in specific brain regions in Alzheimers disease (AD) and BDNF gene polymorphisms have been suggested to influence AD risk, hippocampal function, and memory. We investigated whether the polymorphisms at the BDNF 196 and 270 loci were associated with AD in a clinical and neuropathological cohort of 116 AD cases and 77 control subjects. To determine how BDNF protein levels relate to BDNF polymorphisms and AD pathology, we also measured BDNF in temporal association cortex, frontal association cortex, and cerebellum in 57 of the AD and 21 control cases. BDNF protein levels in temporal neocortex of the AD brains were reduced by 33% compared to control brains, whereas levels were unchanged in frontal and cerebellar cortex. The BDNF genotypes were not significantly associated with a diagnosis of AD, although the BDNF 270 C allele was slightly overrepresented among carriers of the APOEepsilon4 allele. Moreover, BDNF protein levels did not differ between the various BDNF genotypes and alleles. Neuropathologically, the loss of BDNF in AD showed a weak correlation with accumulation of neuritic amyloid plaques and loss of the neuronal/synaptic marker synaptophysin. The results suggest that the investigated BDNF polymorphisms are neither robust genetic risk factors nor determinants of BDNF protein levels in AD.

Technology in Parkinson's disease: Challenges and opportunities

The miniaturization, sophistication, proliferation, and accessibility of technologies are enabling the capture of more and previously inaccessible phenomena in Parkinsons disease (PD). However, more information has not translated into a greater understanding of disease complexity to satisfy diagnostic and therapeutic needs. Challenges include noncompatible technology platforms, the need for wide‐scale and long‐term deployment of sensor technology (among vulnerable elderly patients in particular), and the gap between the “big data” acquired with sensitive measurement technologies and their limited clinical application. Major opportunities could be realized if new technologies are developed as part of open‐source and/or open‐hardware platforms that enable multichannel data capture sensitive to the broad range of motor and nonmotor problems that characterize PD and are adaptable into self‐adjusting, individualized treatment delivery systems. The International Parkinson and Movement Disorders Society Task Force on Technology is entrusted to convene engineers, clinicians, researchers, and patients to promote the development of integrated measurement and closed‐loop therapeutic systems with high patient adherence that also serve to (1) encourage the adoption of clinico‐pathophysiologic phenotyping and early detection of critical disease milestones, (2) enhance the tailoring of symptomatic therapy, (3) improve subgroup targeting of patients for future testing of disease‐modifying treatments, and (4) identify objective biomarkers to improve the longitudinal tracking of impairments in clinical care and research. This article summarizes the work carried out by the task force toward identifying challenges and opportunities in the development of technologies with potential for improving the clinical management and the quality of life of individuals with PD.

Inertial Sensor-Based Stride Parameter Calculation From Gait Sequences in Geriatric Patients

A detailed and quantitative gait analysis can provide evidence of various gait impairments in elderly people. To provide an objective decision-making basis for gait analysis, simple applicable tests analyzing a high number of strides are required. A mobile gait analysis system, which is mounted on shoes, can fulfill these requirements. This paper presents a method for computing clinically relevant temporal and spatial gait parameters. Therefore, an accelerometer and a gyroscope were positioned laterally below each ankle joint. Temporal gait events were detected by searching for characteristic features in the signals. To calculate stride length, the gravity compensated accelerometer signal was double integrated, and sensor drift was modeled using a piece-wise defined linear function. The presented method was validated using GAITRite-based gait parameters from 101 patients (average age 82.1 years). Subjects performed a normal walking test with and without a wheeled walker. The parameters stride length and stride time showed a correlation of 0.93 and 0.95 between both systems. The absolute error of stride length was 6.26 cm on normal walking test. The developed system as well as the GAITRite showed an increased stride length, when using a four-wheeled walker as walking aid. However, the walking aid interfered with the automated analysis of the GAITRite system, but not with the inertial sensor-based approach. In summary, an algorithm for the calculation of clinically relevant gait parameters derived from inertial sensors is applicable in the diagnostic workup and also during long-term monitoring approaches in the elderly population.