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Background Parkinson’s disease (PD) is a progressive neurodegenerative disorder associated with a loss of dopaminergic (DA) neurons. Despite symptomatic therapies, there is currently no disease-modifying treatment to halt neuronal loss in PD. A major hurdle for developing and testing such curative therapies results from the fact that most DA neurons are already lost at the time of the clinical diagnosis, rendering them inaccessible to therapy. Understanding the early pathological changes that precede Lewy body pathology (LBP) and cell loss in PD will likely support the identification of novel diagnostic and therapeutic strategies and help to differentiate LBP-dependent and -independent alterations. Several previous studies identified such specific molecular and cellular changes that occur prior to the appearance of Lewy bodies (LBs) in DA neurons, but a concise map of such early disease events is currently missing. Methods Here, we conducted a literature review to identify and discuss the results of previous studies that investigated cases with incidental Lewy body disease (iLBD), a presumed pathological precursor of PD. Results Collectively, our review demonstrates numerous cellular and molecular neuropathological changes occurring prior to the appearance of LBs in DA neurons. Conclusions Our review provides the reader with a summary of early pathological events in PD that may support the identification of novel therapeutic and diagnostic targets and aid to the development of disease-modifying strategies in PD.

The MAPT gene, encoding the microtubule-associated protein tau on chromosome 17q21.31, is result of an inversion polymorphism, leading to two allelic variants (H1 and H2). Homozygosity for the more common haplotype H1 is associated with an increased risk for several tauopathies, but also for the synucleinopathy Parkinson’s disease (PD). In the present study, we aimed to clarify whether the MAPT haplotype influences expression of MAPT and SNCA, encoding the protein α-synuclein (α-syn), on mRNA and protein levels in postmortem brains of PD patients and controls. We also investigated mRNA expression of several other MAPT haplotype-encoded genes. Postmortem tissues from cortex of fusiform gyrus (ctx-fg) and of the cerebellar hemisphere (ctx-cbl) of neuropathologically confirmed PD patients (n = 95) and age- and sex-matched controls (n = 81) were MAPT haplotype genotyped to identify cases homozygous for either H1 or H2. Relative expression of genes was quantified using real-time qPCR; soluble and insoluble protein levels of tau and α-syn were determined by Western blotting. Homozygosity for H1 versus H2 was associated with increased total MAPT mRNA expression in ctx-fg regardless of disease state. Inversely, H2 homozygosity was associated with markedly increased expression of the corresponding antisense MAPT-AS1 in ctx-cbl. PD patients had higher levels of insoluble 0N3R and 1N4R tau isoforms regardless of the MAPT genotype. The increased presence of insoluble α-syn in PD patients in ctx-fg validated the selected postmortem brain tissue. Our findings in this small, but well controlled cohort of PD and controls support a putative biological relevance of tau in PD. However, we did not identify any link between the disease-predisposing H1/H1 associated overexpression of MAPT with PD status. Further studies are required to gain a deeper understanding of the potential regulatory role of MAPT-AS1 and its association to the disease-protective H2/H2 condition in the context of PD.

Spreading of alpha-synuclein (αSyn) may play an important role in Parkinson’s disease and related synucleinopathies. Passive immunization with anti-αSyn antibodies is a promising method to slow down the spreading process and thereby the progression of synucleinopathies. Currently, it remains elusive which specific characteristics are essential to render therapeutic antibodies efficacious. Here, we established a neuronal co-culture model, in which αSyn species are being released from αSyn-overexpressing cells and induce toxicity in a priori healthy GFP-expressing cells. In this model, we investigated the protective efficacy of three anti-αSyn antibodies. Only two of these antibodies, one C-terminal and one N-terminal, protected from αSyn-induced toxicity by inhibiting the uptake of spreading-competent αSyn from the cell culture medium. Neither the binding epitope nor the affinity of the antibodies towards recombinant αSyn could explain differences in biological efficacy. However, both protective antibodies formed more stable antibody-αSyn complexes than the non-protective antibody. These findings indicate that the stability of antibody-αSyn complexes may be more important to confer protection than the binding epitope or affinity to recombinant αSyn.

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral disease of the brain—caused by human polyomavirus 2. It affects patients whose immune system is compromised by a corresponding underlying disease or by drugs. Patients with an underlying lymphoproliferative disease have the worst prognosis with a mortality rate of up to 90%. Several therapeutic strategies have been proposed but failed to show any benefit so far. Therefore, the primary therapeutic strategy aims to reconstitute the impaired immune system to generate an effective endogenous antiviral response. Recently, anti-PD-1 antibodies and application of allogeneic virus-specific T cells demonstrated promising effects on the outcome in individual PML patients. This article aims to provide a detailed overview of the literature with a focus on these two treatment approaches. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-021-10952-5.

Ataxia telangiectasia is a rare autosomal recessive multisystem disorder caused by mutations in the gene of ATM serine/threonine kinase. It is characterized by neurodegeneration, leading to severe ataxia, immunodeficiency, increased cancer susceptibility, and telangiectasia. Here, we discovered a co-segregation of two ATM gene variants with ataxia telangiectasia in an Egyptian family. While one of these variants (NM_000051.4(ATM_i001):p.(Val128*)) has previously been reported as pathogenic, the other one (NM_000051.4(ATM_i001):p.(Val1729Leu)) is regarded as a variant of uncertain significance. Our findings in this family provide additional evidence for causality of the second variant and argue that its status should be changed to pathogenic.

ZusammenfassungAbdominelle Schmerzen sind oft Konsultationsanlass in Arztpraxen und Notaufnahmen. Die häufigsten Differenzialdiagnosen lassen sich mit gut verfügbarer, kosteneffektiver und risikoarmer Diagnostik (Laboruntersuchungen, Sonographie, Gastroskopie) bestätigen. Zum Ausschluss seltener Ursachen, wie kleiner solider oder hämatologischer Malignome, Stoffwechselstörungen oder Polyneuropathien unterschiedlichster Genese, kann eine erweiterte Diagnostik erforderlich sein. Im Folgenden stellen wir den Fall eines Patienten mit massivsten epigastrischen Beschwerden infolge einer Neuroborreliose vor und rekapitulieren die diagnostischen Schritte zur Abklärung des abdominellen Schmerzes.

This short editorial provides our point of view of the first EURO TAU meeting focusing on tau diagnostics and clinical studies. We cover postmortem analyses toward the identification of new biomarkers, tau imaging as a diagnostic biomarker, cerebrospinal fluid (CSF) sampling with emphasis on tau fragments, blood tests and genetic evaluations for sporadic cases, treatment aspects, drug development and points for future developments toward disease modification of devastating tauopathies.

Diese Ubersicht widmet sich den Aspekten der Arzneimitteltherapiesicherheit in der Pharmakotherapie des Morbus Parkinson, einer der haufigsten chronischen Erkrankungen des Nervensystems. Die Pharmakotherapie des Morbus Parkinson ist beispielhaft fur die Komplexitat im typischerweise neurogeriatrischen Patientenkollektiv. Herausstellung potenzieller Risiken und von Aspekten der Arzneimitteltherapiesicherheit in der Pharmakotherapie des Morbus Parkinson. Selektive Literatur- und Leitlinienrecherche unter Zuhilfenahme von Pubmed sowie der wissenschaftlich-klinischen Erfahrungen der Autoren. Da Parkinson-Patienten meist altere Menschen sind, die infolge von Komorbiditaten mit weiteren Medikamenten therapiert werden, kommt es haufig zu einer komplexen Medikation mit mehr als funf Arzneimitteln. Diese Polymedikation erhoht das Risiko unerwunschter Arzneimittelereignisse, sodass die Medikation der Patienten auf Interaktionen uberpruft und Kontraindikationen ausgeschlossen werden mussen. Damit besteht vermehrter Aufklarungsbedarf bezuglich moglicher arzneimittelbezogener Probleme. Die Komorbiditaten oder die verordneten Arzneimittel konnen Kontrolluntersuchungen erforderlich machen, um arzneimittelbezogene Probleme zu erkennen und die Arzneimitteltherapiesicherheit zu gewahrleisten. Um die gesundheitsbezogene Lebensqualitat und die Qualitat der Arzneimitteltherapie von Parkinson-Patienten zu gewahrleisten, muss die individuell beste Therapie unter Berucksichtigung aller Kontraindikationen, Nebenwirkungen, Kontrolluntersuchungen und Interaktionen gefunden werden. Aufklarungsarbeit kann die Compliance der Patienten erhohen und zur Steigerung der Arzneimitteltherapiesicherheit beitragen.

Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disorder characterized by postural instability and falls, vertical supranuclear gaze palsy, parkinsonism with poor levodopa response, pseudobulbar palsy, and frontal release signs. The natural history of the disease has been previously described. However, the time frame of appearance of clinical milestones and how these symptoms may relate to survival in PSP are unknown. The primary objective was to determine the prevalence of symptoms at different stages of PSP and to estimate the time of appearance of clinical symptoms characteristic of the disease. Second, we determined the association between clinical symptoms and survival. We prospectively studied 35 PSP patients during assessments scheduled every 6 months for up to 2 years. We estimated symptoms prevalence and the association between symptoms and survival. The median age of onset was 65.9 years (IQR 60.6-70.0), and the median time from onset to first assessment was 3.0 years (IQR 2.4-3.9). The most commonly reported symptoms at baseline were: motor (100%) followed by cognitive/behavioral (89%), systemic and bulbar (80%), and sleep disturbances (60%). Slowness of movement, falls, neck stiffness and difficulty looking up/down had high prevalence from baseline, while balance and gait impairment were less common at baseline but increased in prevalence over time. The presence of sleep disturbances, and possibly hallucinations, was associated with increased death risk. Improved recognition of the clinical spectrum and milestones of PSP advances knowledge of the disease, helps earlier diagnosis, and allows prognostic predictions.

Parkinson disease (PD) is a neurodegenerative disorder characterized by massive loss of midbrain dopaminergic neurons. Whereas onset of motor impairments reflects a rather advanced stage of the disorder, hyposmia often marks the beginning of the disease. Little is known about the role of the nigro-striatal system in olfaction under physiological conditions and the anatomical basis of hyposmia in PD. Yet, the early occurrence of olfactory dysfunction implies that pathogens such as environmental toxins could incite the disease via the olfactory system. In the present study, we demonstrate a dopaminergic innervation from neurons in the substantia nigra to the olfactory bulb by axonal tracing studies. Injection of two dopaminergic neurotoxins-1-methyl-4-phenylpyridinium and 6-hydroxydopamine-into the olfactory bulb induced a decrease in the number of dopaminergic neurons in the substantia nigra. In turn, ablation of the nigral projection led to impaired olfactory perception. Hyposmia following dopaminergic deafferentation was reversed by treatment with the D1/D2/D3 dopamine receptor agonist rotigotine. Hence, we demonstrate for the first time the existence of a direct dopaminergic projection into the olfactory bulb and identify its origin in the substantia nigra in rats. These observations may provide a neuroanatomical basis for invasion of environmental toxins into the basal ganglia and for hyposmia as frequent symptom in PD.

Progressive supranuclear palsy (PSP) is a sporadic and progressive neurodegenerative disease, most often leading to a symmetric, akinetic-rigid syndrome with prominent postural instability, vertical supranuclear gaze palsy, and cognitive decline. It belongs to the family of tauopathies and involves both cortical and subcortical structures. There is evidence from laboratory as well as in vivo studies suggesting that mitochondrial energy metabolism is impaired in PSP. Furthermore, several findings suggest that a failure in mitochondrial energy production might act as an upstream event in the chain of pathological events leading to the aggregation of tau and neuronal cell death. Agents targeting mitochondrial dysfunction have already shown a positive effect in a phase II study; however, further studies to verify these results need to be conducted. This review will focus on the pathophysiological concept of mitochondrial dysfunction in PSP and its possible role as a therapeutic target.

Progressive supranuclear palsy (PSP) is a tauopathy, presenting clinically most often with a symmetrical akinetic-rigid syndrome, postural instability, supranuclear gaze palsy and frontal dementia. In the absence of reliably validated biomarkers, the diagnosis of PSP in vivo is presently based on clinical criteria, which to date do not include supporting imaging findings, as is accepted for other neurodegenerative diseases. However, data from conventional magnetic resonance imaging (MRI) and various advanced MRI techniques including magnetic resonance volumetry, voxel-based morphometry, diffusion-weighted and diffusion-tensor imaging, magnetization transfer imaging and proton resonance spectroscopy suggest that MRI can contribute valuable information for the differential diagnosis of PSP. We review here the presently published literature concerning MRI in PSP and discuss the potential role of MRI in differentiating PSP from other parkinsonian syndromes.

Cerebral dopamine depletion is the hallmark of Parkinson disease. Because dopamine modulates ontogenetic neurogenesis, depletion of dopamine might affect neural precursors in the subependymal zone and subgranular zone of the adult brain. Here we provide ultrastructural evidence showing that highly proliferative precursors in the adult subependymal zone express dopamine receptors and receive dopaminergic afferents. Experimental depletion of dopamine in rodents decreases precursor cell proliferation in both the subependymal zone and the subgranular zone. Proliferation is restored completely by a selective agonist of D2-like (D2L) receptors. Experiments with neural precursors from the adult subependymal zone grown as neurosphere cultures confirm that activation of D2L receptors directly increases the proliferation of these precursors. Consistently, the numbers of proliferating cells in the subependymal zone and neural precursor cells in the subgranular zone and olfactory bulb are reduced in postmortem brains of individuals with Parkinson disease. These observations suggest that the generation of neural precursor cells is impaired in Parkinson disease as a consequence of dopaminergic denervation.