Search

The intracellular misfolding and accumulation of alpha-synuclein into structures collectively called Lewy pathology (LP) is a central phenomenon for the pathogenesis of synucleinopathies, including Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Understanding the molecular architecture of LP is crucial for understanding synucleinopathy disease origins and progression. Here we used a technique called biotinylation by antibody recognition (BAR) to label total (BAR-SYN1) and pathological alpha-synuclein (BAR-PSER129) in situ for subsequent mass spectrometry analysis. Results showed superior immunohistochemical detection of LP following the BAR-PSER129 protocol, particularly for fibers and punctate pathology within the striatum and cortex. Mass spectrometry analysis of BAR-PSER129–labeled LP identified 261 significantly enriched proteins in the synucleinopathy brain when compared to nonsynucleinopathy brains. In contrast, BAR-SYN1 did not differentiate between disease and nonsynucleinopathy brains. Pathway analysis of BAR-PSER129–enriched proteins revealed enrichment for 718 pathways; notably, the most significant KEGG pathway was PD, and Gene Ontology (GO) cellular compartments were the vesicle, extracellular vesicle, extracellular exosome, and extracellular organelle. Pathway clustering revealed several superpathways, including metabolism, mitochondria, lysosome, and intracellular vesicle transport. Validation of the BAR-PSER129–identified protein hemoglobin beta (HBB) by immunohistochemistry confirmed the interaction of HBB with PSER129 Lewy neurites and Lewy bodies. In summary, BAR can be used to enrich for LP from formalin-fixed human primary tissues, which allowed the determination of molecular signatures of LP. This technique has broad potential to help understand the phenomenon of LP in primary human tissue and animal models.

In PNAS, Li et al. (1) report the pathological findings in a single patient with Parkinson’s disease (PD) who received transplantation of embryonic dopamine grafts derived from four donors placed into the right putamen 24 y before death. The patient was 59 y of age at the time of surgery and was reported to have experienced marked clinical improvement after a latency of ∼12 mo (originally reported in ref. 2). Bilateral benefits (predominantly on the left side) were noted with respect to rigidity, bradykinesia, rest tremor, and motor fluctuations, and were of sufficient magnitude that levodopa was withdrawn 32 mo following surgery. Levodopa was reinstated at 64 mo at a dose one-third of that used preoperatively and remained unchanged for the life of the patient. Still motor benefits were maintained for ∼10 y. Thereafter, the patient experienced progressive deterioration in motor function and developed a progressive dementia at year 14. At postmortem examination, the investigators reported the survival of ∼42,000 grafted dopaminergic neurons with extensive putamenal dopaminergic innervation. Approximately 11–12% of residual grafted neurons contained α-synuclein aggregates. This case suggests that the original goals of cell replacement therapy for PD, namely, survival of implanted dopamine neurons, striatal reinnervation, and clinical benefit, were met. This is the longest postgrafting interval reported for any PD patient who has undergone a postmortem examination. It is a fascinating case that indicates that grafted fetal dopaminergic cells can survive for almost a quarter of a century and provide extensive striatal innervation. Previous reports have demonstrated similar findings at postmortem performed 18 mo (3) and 4–16 y after grafting (4⇓⇓–7); the present study suggests that these findings can endure for the life of the patient. Importantly, the authors report that fetal nigral grafting in this patient was associated with long-term motor benefit … [↵][1]1To whom correspondence should be addressed. Email: jkordowe{at}rush.edu. [1]: #xref-corresp-1-1

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Despite intense investigations, no effective therapy is available to stop its onset or halt its progression. The present study evaluates the ability of peptide corresponding to the NF-kappaB essential modifier-binding domain (NBD) of IkappaB kinase alpha (IKKalpha) or IKKbeta to prevent nigrostriatal degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD and establish a role for NF-kappaB in human parkinsonism. First, we found that NF-kappaB was activated within the substantia nigra pars compacta of PD patients and MPTP-intoxicated mice. However, i.p. injection of wild-type NBD peptide reduced nigral activation of NF-kappaB, suppressed nigral microglial activation, protected both the nigrostriatal axis and neurotransmitters, and improved motor functions in MPTP-intoxicated mice. These findings were specific because mutated NBD peptide had no effect. We conclude that selective inhibition of NF-kappaB activation by NBD peptide may be of therapeutic benefit for PD patients.

Huntington’s disease (HD) is a fatal, genetic, neurological disorder resulting from a trinucleotide repeat expansion in the gene that encodes for the protein huntingtin. These excessive repeats confer a toxic gain of function on huntingtin, which leads to the degeneration of striatal and cortical neurons and a devastating motor, cognitive, and psychological disorder. Trophic factor administration has emerged as a compelling potential therapy for a variety of neurodegenerative disorders, including HD. We previously demonstrated that viral delivery of glial cell line-derived neurotrophic factor (GDNF) provides structural and functional neuroprotection in a rat neurotoxin model of HD. In this report we demonstrate that viral delivery of GDNF into the striatum of presymptomatic mice ameliorates behavioral deficits on the accelerating rotorod and hind limb clasping tests in transgenic HD mice. Behavioral neuroprotection was associated with anatomical preservation of the number and size of striatal neurons from cell death and cell atrophy. Additionally, GDNF-treated mice had a lower percentage of neurons containing mutant huntingtin-stained inclusion bodies, a hallmark of HD pathology. These data further support the concept that viral vector delivery of GDNF may be a viable treatment for patients suffering from HD.

Neural and stem cell transplantation is emerging as a potential treatment for neurodegenerative diseases. Transplantation of specific committed neuroblasts (fetal neurons) to the adult brain provides such scientific exploration of these new potential therapies. Huntington's disease (HD) is a fatal, incurable autosomal dominant (CAG repeat expansion of huntingtin protein) neurodegenerative disorder with primary neuronal pathology within the caudate–putamen (striatum). In a clinical trial of human fetal striatal tissue transplantation, one patient died 18 months after transplantation from cardiovascular disease, and postmortem histological analysis demonstrated surviving transplanted cells with typical morphology of the developing striatum. Selective markers of both striatal projection and interneurons such as dopamine and c-AMP-related phosphoprotein, calretinin, acetylcholinesterase, choline acetyltransferase, tyrosine hydroxylase, calbindin, enkephalin, and substance P showed positive transplant regions clearly innervated by host tyrosine hydroxylase fibers. There was no histological evidence of immune rejection including microglia and macrophages. Notably, neuronal protein aggregates of mutated huntingtin, which is typical HD neuropathology, were not found within the transplanted fetal tissue. Thus, although there is a genetically predetermined process causing neuronal death within the HD striatum, implanted fetal neural cells lacking the mutant HD gene may be able to replace damaged host neurons and reconstitute damaged neuronal connections. This study demonstrates that grafts derived from human fetal striatal tissue can survive, develop, and are unaffected by the disease process, at least for 18 months, after transplantation into a patient with HD.

Age-associated memory impairment occurs frequently in primates. Based on the established importance of both the perforant path and N-methyl-D-aspartate (NMDA) receptors in memory formation, we investigated the glutamate receptor distribution and immunofluorescence intensity within the dentate gyrus of juvenile, adult, and aged macaque monkeys with the combined use of subunit-specific antibodies and quantitative confocal laser scanning microscopy. Here we demonstrate that aged monkeys, compared to adult monkeys, exhibit a 30.6% decrease in the ratio of NMDA receptor subunit 1 (NMDAR1) immunofluorescence intensity within the distal dendrites of the dentate gyrus granule cells, which receive the perforant path input from the entorhinal cortex, relative to the proximal dendrites, which receive an intrinsic excitatory input from the dentate hilus. The intradendritic alteration in NMDAR1 immunofluorescence occurs without a similar alteration of non-NMDA receptor subunits. Further analyses using synaptophysin as a reflection of total synaptic density and microtubule-associated protein 2 as a dendritic structural marker demonstrated no significant difference in staining intensity or area across the molecular layer in aged animals compared to the younger animals. These findings suggest that, in aged monkeys, a circuit-specific alteration in the intradendritic concentration of NMDAR1 occurs without concomitant gross structural changes in dendritic morphology or a significant change in the total synaptic density across the molecular layer. This alteration in the NMDA receptor-mediated input to the hippocampus from the entorhinal cortex may represent a molecular/cellular substrate for age-associated memory impairments.