Levodopa/carbidopa intestinal gel (LCIG) infusion as mono- or combination therapy.

Levodopa/carbidopa intestinal gel (LCIG) infusion is an effective escalating therapy in patients with Parkinson disease (PD) suffering from motor fluctuations and dyskinesia. Levodopa/carbidopa given continuously as infusion provides an optimized application of the most effective and best tolerable antiparkinsonian drug. It has been proven to have a superior motor effect compared with oral levodopa and to improve also non-motor symptoms. However, invasiveness, discomfort resulting from carrying an external device, and side effects associated with the way of administration limit its application in PD patients. At present, there are no guidelines that delineate to which patients LCIG should be offered as monotherapy, in combination with oral and/or transdermal medication, or as additional therapy to deep brain stimulation (DBS). Based on clinical studies, we propose an expert consensus for neurologists addressing the question when LCIG therapy should be recommended and in which cases LCIG infusion is suggested in combination with other antiparkinsonian drugs and/or DBS. We describe how LCIG should be initiated and what we consider necessary for clinical follow-up. We suggest an algorithm facilitating decision-making with respect to the currently available invasive PD therapies, namely infusion with subcutaneous apomorphine, LCIG, and DBS.

[The Geriatric Patient with Parkinson's Disease - a Neurological Challenge]. / Der geriatrische Parkinson-Patient - eine neurologische Herausforderung.

Geriatric patients with Parkinson's disease (PD) represent a particular challenge in terms of diagnostics and treatment. This overview article addresses age-related characteristics of this patient group and discusses particularities in PD symptoms in this age group, frequent comorbidities and the resulting polypharmacy. Questions regarding the availability of specialist and therapist care as well as end-of-life aspects are discussed. While comprehensive care structures are not always available, this patient group requires a multidisciplinary treatment team supervised by neurologists with ample experience in PD treatment.

Acute disseminated encephalomyelitis following Tdap vaccination and bacterial meningoencephalitis.

INTRODUCTION: Association of Acute Disseminated Encephalomyelitis (ADEM) with both recent vaccination and viral infections is well described in current literature. However, the coincidence of ADEM and bacterial infections has been rarely documented. In this report, we present a case of ADEM which occurred after bacterial meningoencephalitis and prior vaccination against tetanus, diphtheria, and pertussis (Tdap). CASE PRESENTATION: A 62-year old woman was hospitalized with an upper respiratory tract infection three weeks after Tdap triple vaccination. A few days after admission, she became somnolent and developed meningism. Cerebrospinal fluid (CSF) analysis revealed pleocytosis and increased protein/lactate levels compatible with bacterial meningoencephalitis. The patient was treated with intravenous antibacterial triple therapy in combination with dexamethasone leading to a significant improvement of clinical symptoms and improvement of CSF parameters. Five days later, the patient's condition worsened again, and she developed aphasia and right-sided hemiparesis. A magnetic resonance imaging (MRI) scan revealed distinct fluid-attenuated inversion recovery sequence (FLAIR)-hyperintense lesions in both hemispheres. Following brain biopsy, the diagnosis of ADEM was made and methylprednisolone pulse therapy was initiated for five days leading to a nearly complete remission of symptoms. CONCLUSION: ADEM is a neurological syndrome which may be associated with bacterial infection of the central nervous system (CNS). We hypothesize that the preceding Tdap triple vaccination may have contributed to the development of ADEM.

Identification of new kinase clusters required for neurite outgrowth and retraction by a loss-of-function RNA interference screen.

Disruption of synaptic integrity, loss of connectivity and axodendritic degeneration are early and essential components of neurodegeneration. Although neuronal cell death mechanisms have been thoroughly investigated, less is known about the signals involved in axodendritic damage and the processes involved in regeneration. Here we conducted a genome-wide RNA interference-based forward genetic screen, using small interfering RNA targeting all human kinases, and identified clusters of kinases families essential for growth cone collapse, neurite retraction and neurite outgrowth. Of 59 kinases identified as positive regulators of neurite outgrowth, almost 50% were in the tyrosine kinase/tyrosine kinase-like (TK/TKL) receptor subgroups, underlining the importance of extracellular ligands in this process. Neurite outgrowth was inhibited by 66 other kinases, none of which were TK/TKL members, whereas 79 kinases inhibited lysophosphatidic acid-induced neurite retraction. Twenty kinases were involved in both inhibitory processes suggesting shared mechanisms. Within this group of 20 kinases, some (ULK1, PDK1, MAP4K4) have been implicated previously in axonal events, but others (MAST2, FASTK, CKM and DGUOK) have not. For a subset of kinases, the effect on neurite outgrowth was validated in rat primary cerebellar cultures. The ability to affect regeneration was further tested in a model of axodendritic lesion using primary rat midbrain cultures. Finally, we demonstrated that haploinsufficiency of two members of the AGC kinase subgroup, ROCK1 and PKN1, was able to suppress retinal degeneration in Drosophila model of class III Autosomal Dominant Retinitis Pigmentosa.

Cyclin-dependent kinase 5 is an upstream regulator of mitochondrial fission during neuronal apoptosis.

Under physiological conditions, mitochondrial morphology dynamically shifts between a punctuate appearance and tubular networks. However, little is known about upstream signal transduction pathways that regulate mitochondrial morphology. We show that mitochondrial fission is a very early and kinetically invariant event during neuronal cell death, which causally contributes to cytochrome c release and neuronal apoptosis. Using a small molecule CDK5 inhibitor, as well as a dominant-negative CDK5 mutant and RNAi knockdown experiments, we identified CDK5 as an upstream signalling kinase that regulates mitochondrial fission during apoptosis of neurons. Vice versa, our study shows that mitochondrial fission is a modulator contributing to CDK5-mediated neurotoxicity. Thereby, we provide a link that allows integration of CDK5 into established neuronal apoptosis pathways.

Growth/differentiation factor-15/macrophage inhibitory cytokine-1 is a novel trophic factor for midbrain dopaminergic neurons in vivo.

Transforming growth factor-betas (TGF-betas) constitute an expanding family of multifunctional cytokines with prominent roles in development, cell proliferation, differentiation, and repair. We have cloned, expressed, and raised antibodies against a distant member of the TGF-betas, growth/differentiation factor-15 (GDF-15). GDF-15 is identical to macrophage inhibitory cytokine-1 (MIC-1). GDF-15/MIC-1 mRNA and protein are widely distributed in the developing and adult CNS and peripheral nervous systems, including choroid plexus and CSF. GDF-15/MIC-1 is a potent survival promoting and protective factor for cultured and iron-intoxicated dopaminergic (DAergic) neurons cultured from the embryonic rat midbrain floor. The trophic effect of GDF-15/MIC-1 was not accompanied by an increase in cell proliferation and astroglial maturation, suggesting that GDF-15/MIC-1 probably acts directly on neurons. GDF-15/MIC-1 also protects 6-hydroxydopamine (6-OHDA)-lesioned nigrostriatal DAergic neurons in vivo. Unilateral injections of GDF-15/MIC-1 into the medial forebrain bundle just above the substantia nigra (SN) and into the left ventricle (20 microgram each) immediately before a 6-OHDA injection (8 microgram) prevented 6-OHDA-induced rotational behavior and significantly reduced losses of DAergic neurons in the SN. This protection was evident for at least 1 month. Administration of 5 microgram of GDF-15/MIC-1 in the same paradigm also provided significant neuroprotection. GDF-15/MIC-1 also promoted the serotonergic phenotype of cultured raphe neurons but did not support survival of rat motoneurons. Thus, GDF-15/MIC-1 is a novel neurotrophic factor with prominent effects on DAergic and serotonergic neurons. GDF-15/MIC-1 may therefore have a potential for the treatment of Parkinson's disease and disorders of the serotonergic system.

Alpha-Synuclein affects neurite morphology, autophagy, vesicle transport and axonal degeneration in CNS neurons.

Many neuropathological and experimental studies suggest that the degeneration of dopaminergic terminals and axons precedes the demise of dopaminergic neurons in the substantia nigra, which finally results in the clinical symptoms of Parkinson disease (PD). The mechanisms underlying this early axonal degeneration are, however, still poorly understood. Here, we examined the effects of overexpression of human wildtype alpha-synuclein (αSyn-WT), a protein associated with PD, and its mutant variants αSyn-A30P and -A53T on neurite morphology and functional parameters in rat primary midbrain neurons (PMN). Moreover, axonal degeneration after overexpression of αSyn-WT and -A30P was analyzed by live imaging in the rat optic nerve in vivo. We found that overexpression of αSyn-WT and of its mutants A30P and A53T impaired neurite outgrowth of PMN and affected neurite branching assessed by Sholl analysis in a variant-dependent manner. Surprisingly, the number of primary neurites per neuron was increased in neurons transfected with αSyn. Axonal vesicle transport was examined by live imaging of PMN co-transfected with EGFP-labeled synaptophysin. Overexpression of all αSyn variants significantly decreased the number of motile vesicles and decelerated vesicle transport compared with control. Macroautophagic flux in PMN was enhanced by αSyn-WT and -A53T but not by αSyn-A30P. Correspondingly, colocalization of αSyn and the autophagy marker LC3 was reduced for αSyn-A30P compared with the other αSyn variants. The number of mitochondria colocalizing with LC3 as a marker for mitophagy did not differ among the groups. In the rat optic nerve, both αSyn-WT and -A30P accelerated kinetics of acute axonal degeneration following crush lesion as analyzed by in vivo live imaging. We conclude that αSyn overexpression impairs neurite outgrowth and augments axonal degeneration, whereas axonal vesicle transport and autophagy are severely altered.

Elevated α-synuclein caused by SNCA gene triplication impairs neuronal differentiation and maturation in Parkinson's patient-derived induced pluripotent stem cells.

We have assessed the impact of α-synuclein overexpression on the differentiation potential and phenotypic signatures of two neural-committed induced pluripotent stem cell lines derived from a Parkinson's disease patient with a triplication of the human SNCA genomic locus. In parallel, comparative studies were performed on two control lines derived from healthy individuals and lines generated from the patient iPS-derived neuroprogenitor lines infected with a lentivirus incorporating a small hairpin RNA to knock down the SNCA mRNA. The SNCA triplication lines exhibited a reduced capacity to differentiate into dopaminergic or GABAergic neurons and decreased neurite outgrowth and lower neuronal activity compared with control cultures. This delayed maturation phenotype was confirmed by gene expression profiling, which revealed a significant reduction in mRNA for genes implicated in neuronal differentiation such as delta-like homolog 1 (DLK1), gamma-aminobutyric acid type B receptor subunit 2 (GABABR2), nuclear receptor related 1 protein (NURR1), G-protein-regulated inward-rectifier potassium channel 2 (GIRK-2) and tyrosine hydroxylase (TH). The differentiated patient cells also demonstrated increased autophagic flux when stressed with chloroquine. We conclude that a two-fold overexpression of α-synuclein caused by a triplication of the SNCA gene is sufficient to impair the differentiation of neuronal progenitor cells, a finding with implications for adult neurogenesis and Parkinson's disease progression, particularly in the context of bioenergetic dysfunction.

GDF-15/MIC-1 a novel member of the TGF-beta superfamily.

We have cloned, expressed, and raised antibodies against a novel member of the TGF-beta superfamily, growth/differentiation factor-15 (GDF-15). The predicted protein is identical to macrophage inhibitory cytokine-1 (MIC-1), which was discovered simultaneously. GDF-15 is a more distant member of the TGF-beta superfamily and does not belong to one of the known TGF-beta subfamilies. In the CNS, GDF-15/MIC-1 mRNA is abundantly expressed by the choroid plexus. In addition we have preliminary evidence that GDF-15/MIC-1 is a potent trophic factor for selected classes of neurons in vitro and in vivo. Thus, GDF-15 is a novel neurotrophic factor with prospects for the treatment of disorders of the CNS.

ROCK2 is a major regulator of axonal degeneration, neuronal death and axonal regeneration in the CNS.

The Rho/ROCK/LIMK pathway is central for the mediation of repulsive environmental signals in the central nervous system. Several studies using pharmacological Rho-associated protein kinase (ROCK) inhibitors have shown positive effects on neurite regeneration and suggest additional pro-survival effects in neurons. However, as none of these drugs is completely target specific, it remains unclear how these effects are mediated and whether ROCK is really the most relevant target of the pathway. To answer these questions, we generated adeno-associated viral vectors to specifically downregulate ROCK2 and LIM domain kinase (LIMK)-1 in rat retinal ganglion cells (RGCs) in vitro and in vivo. We show here that specific knockdown of ROCK2 and LIMK1 equally enhanced neurite outgrowth of RGCs on inhibitory substrates and both induced substantial neuronal regeneration over distances of more than 5 mm after rat optic nerve crush (ONC) in vivo. However, only knockdown of ROCK2 but not LIMK1 increased survival of RGCs after optic nerve axotomy. Moreover, knockdown of ROCK2 attenuated axonal degeneration of the proximal axon after ONC assessed by in vivo live imaging. Mechanistically, we demonstrate here that knockdown of ROCK2 resulted in decreased intraneuronal activity of calpain and caspase 3, whereas levels of pAkt and collapsin response mediator protein 2 and autophagic flux were increased. Taken together, our data characterize ROCK2 as a specific therapeutic target in neurodegenerative diseases and demonstrate new downstream effects of ROCK2 including axonal degeneration, apoptosis and autophagy.

GDNF and NT-4 protect midbrain dopaminergic neurons from toxic damage by iron and nitric oxide.

Free radical formation is considered to be a major cause of dopaminergic (DAergic) cell death in the substantia nigra leading to Parkinson's disease (PD). In this study we employed several radical donors including iron and sodium nitroprusside to induce toxic effects on DAergic neurons cultured from the embryonic rat midbrain floor. Overall cell survival was assessed by assaying LDH, and DAergic neuron survival was monitored by counting tyrosine hydroxylase-positive cells. Our data suggest that the DAergic neuron population is about fourfold more susceptible to free-radical-mediated damage than the total population of midbrain neurons. Application of the neurotrophic factors GDNF and NT-4, for which DAergic neurons have specific receptors, prior to toxin administration protected these neurons from toxin-mediated death, which, fully or in part, occurs under the signs of apoptosis. These findings underscore the importance of GDNF and NT-4 in designing future therapeutical concepts for PD.

Midbrain dopaminergic neurons are protected from radical induced damage by GDF-5 application. Short communication.

Embryonic day 14 rat midbrain cultures were kept for 7 days in vitro and then intoxicated with radical donors iron and sodium-nitroprusside for 24 h. Tyrosine-hydroxylase positive neurons in cultures which were additionally treated with growth/differentiation factor-5 (GDF-5) survived to a significantly higher percentage as compared to sister cultures without factor supplementation. Since the degeneration of TH positive cells is a key feature in Parkinson's disease, GDF-5 might be a putative therapeutical agent for this disorder.

Differential transgene expression in brain cells in vivo and in vitro from AAV-2 vectors with small transcriptional control units.

Adeno-associated- (AAV) based vectors are promising tools for gene therapy applications in several organs, including the brain, but are limited by their small genome size. Two short promoters, the human synapsin 1 gene promoter (hSYN) and the murine cytomegalovirus immediate early promoter (mCMV), were evaluated in bicistronic AAV-2 vectors for their expression profiles in cultured primary brain cells and in the rat brain. Whereas transgene expression from the hSYN promoter was exclusively neuronal, the murine CMV promoter targeted expression mainly to astrocytes in vitro and showed weak transgene expression in vivo in retinal and cortical neurons, but strong expression in thalamic neurons. We propose that neuron specific transgene expression in combination with enhanced transgene capacity will further substantially improve AAV based vector technology.