Striatal Cholinergic Dysregulation after Neonatal Decrease in X-Linked Dystonia Parkinsonism-Related TAF1 Isoforms.

BACKGROUND: X-linked dystonia parkinsonism is a generalized, progressive dystonia followed by parkinsonism with onset in adulthood and accompanied by striatal neurodegeneration. Causative mutations are located in a noncoding region of the TATA-box binding protein-associated factor 1 (TAF1) gene and result in aberrant splicing. There are 2 major TAF1 isoforms that may be decreased in symptomatic patients, including the ubiquitously expressed canonical cTAF1 and the neuronal-specific nTAF1. OBJECTIVE: The objective of this study was to determine the behavioral and transcriptomic effects of decreased cTAF1 and/or nTAF1 in vivo. METHODS: We generated adeno-associated viral (AAV) vectors encoding microRNAs targeting Taf1 in a splice-isoform selective manner. We performed intracerebroventricular viral injections in newborn mice and rats and intrastriatal infusions in 3-week-old rats. The effects of Taf1 knockdown were assayed at 4 months of age with evaluation of motor function, histology, and RNA sequencing of the striatum, followed by its validation. RESULTS: We report motor deficits in all cohorts, more pronounced in animals injected at P0, in which we also identified transcriptomic alterations in multiple neuronal pathways, including the cholinergic synapse. In both species, we show a reduced number of striatal cholinergic interneurons and their marker mRNAs after Taf1 knockdown in the newborn. CONCLUSION: This study provides novel information regarding the requirement for TAF1 in the postnatal maintenance of striatal cholinergic neurons, the dysfunction of which is involved in other inherited forms of dystonia. © 2021 International Parkinson and Movement Disorder Society.

Fiber-modified adenovirus for central nervous system Parkinson's disease gene therapy.

Gene-based therapies for neurological diseases continue to develop briskly. As disease mechanisms are elucidated, flexible gene delivery platforms incorporating transcriptional regulatory elements, therapeutic genes and targeted delivery are required for the safety and efficacy of these approaches. Adenovirus serotype 5 (Ad5)-based vectors can carry large genetic payloads to provide this flexibility, but do not transduce neuronal cells efficiently. To address this, we have developed a tropism-modified Ad5 vector with neuron-selective targeting properties for evaluation in models of Parkinson disease therapy. A panel of tropism-modified Ad5 vectors was screened for enhanced gene delivery in a neuroblastoma cell line model system. We used these observations to design and construct an unbiased Ad vector platform, consisting of an unmodified Ad5 and a tropism-modified Ad5 vector containing the fiber knob domain from canine Ad serotype 2 (Ad5-CGW-CK2). Delivery to the substantia nigra or striatum showed that this vector produced a neuronally-restricted pattern of gene expression. Many of the transduced neurons were from regions with afferent projections to the injection site, implicating that the vector binds the presynaptic terminal resulting in presynaptic transduction. We show that Ad5-CGW-CK2 can selectively transduce neurons in the brain and hypothesize that this modular platform is potentially adaptable to clinical use.

Transduction of brain dopamine neurons by adenoviral vectors is modulated by CAR expression: rationale for tropism modified vectors in PD gene therapy.

BACKGROUND: Gene-based therapy is a new paradigm for the treatment of Parkinson disease (PD) and offers considerable promise for precise targeting and flexibility to impact multiple pathobiological processes for which small molecule agents are not available. Some success has been achieved utilizing adeno-associated virus for this approach, but it is likely that the characteristics of this vector system will ultimately create barriers to progress in clinical therapy. Adenovirus (Ad) vector overcomes limitations in payload size and targeting. The cellular tropism of Ad serotype 5 (Ad5)-based vectors is regulated by the Ad attachment protein binding to its primary cellular receptor, the coxsackie and adenovirus receptor (CAR). Many clinically relevant tissues are refractory to Ad5 infection due to negligible CAR levels but can be targeted by tropism-modified, CAR-independent forms of Ad. Our objective was to evaluate the role of CAR protein in transduction of dopamine (DA) neurons in vivo. METHODOLOGY/PRINCIPAL FINDINGS: Ad5 was delivered to the substantia nigra (SN) in wild type (wt) and CAR transgenic animals. Cellular tropism was assessed by immunohistochemistry (IHC) in the SN and striatal terminals. CAR expression was assessed by western blot and IHC. We found in wt animals, Ad5 results in robust transgene expression in astrocytes and other non-neuronal cells but poor infection of DA neurons. In contrast, in transgenic animals, Ad5 infects SNc neurons resulting in expression of transduced protein in their striatal terminals. Western blot showed low CAR expression in the ventral midbrain of wt animals compared to transgenic animals. Interestingly, hCAR protein localizes with markers of post-synaptic structures, suggesting synapses are the point of entry into dopaminergic neurons in transgenic animals. CONCLUSIONS/SIGNIFICANCE: These findings demonstrate that CAR deficiency limits infection of wild type DA neurons by Ad5 and provide a rationale for the development of tropism-modified, CAR-independent Ad-vectors for use in gene therapy of human PD.

Design of clinical trials of gene therapy in Parkinson disease.

No current therapy for Parkinson disease has been shown to slow or reverse the progressive course of the disease. As a departure from traditional treatments, gene therapy approaches provide a new hope for realizing this long-sought goal; but before they can be widely employed for use in patients, they must first be submitted to the rigorous safety and efficacy standards of the clinical trial. Some of the challenges of gene therapy clinical trial design are similar to those in studies of conventional pharmacological agents and include addressing the heterogeneity of the disease, the need for clinical and surrogate endpoints, and the issue of distinguishing "symptomatic" from "neuroprotective" effects. Gene therapy trials also raise the issues of the risks of viral therapy, issues of dose-response, the need for sham surgery, and the long duration of risks and benefits. We conclude that the most feasible designs are for those treatments that are expected to produce a rapid improvement in directly observable symptoms. Trials of agents which are expected to produce only a slowing of progression and not a reversal of the disease course are likely to take much longer and will require the development of methods to assess quality of life and other non-motor aspects of the disease.

Quantitative 1H magnetic resonance spectroscopic imaging determines therapeutic immunization efficacy in an animal model of Parkinson's disease.

Nigrostriatal degeneration, the pathological hallmark of Parkinson's disease (PD), is mirrored by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication. MPTP-treated animals show the common behavioral, motor, and pathological features of human disease. We demonstrated previously that adoptive transfer of Copaxone (Cop-1) immune cells protected the nigrostriatal dopaminergic pathway in MPTP-intoxicated mice. Herein, we evaluated this protection by quantitative proton magnetic resonance spectroscopic imaging (1H MRSI). 1H MRSI performed in MPTP-treated mice demonstrated that N-acetyl aspartate (NAA) was significantly diminished in the substantia nigra pars compacta (SNpc) and striatum, regions most affected in human disease. When the same regions were coregistered with immunohistochemical stains for tyrosine hydroxylase, numbers of neuronal bodies and termini were similarly diminished. MPTP-intoxicated animals that received Cop-1 immune cells showed NAA levels, in the SNpc and striatum, nearly equivalent to PBS-treated animals. Moreover, adoptive transfer of immune cells from ovalbumin-immunized to MPTP-treated mice failed to alter NAA levels or protect dopaminergic neurons and their projections. These results demonstrate that 1H MRSI can evaluate dopaminergic degeneration and its protection by Cop-1 immunization strategies. Most importantly, the results provide a monitoring system to assess therapeutic outcomes for PD.

Therapeutic immunization protects dopaminergic neurons in a mouse model of Parkinson's disease.

Degeneration of the nigrostriatal dopaminergic pathway, the hallmark of Parkinson's disease, can be recapitulated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice. Herein, we demonstrate that adoptive transfer of copolymer-1 immune cells to MPTP recipient mice leads to T cell accumulation within the substantia nigra pars compacta, suppression of microglial activation, and increased local expression of astrocyte-associated glial cell line-derived neurotrophic factor. This immunization strategy resulted in significant protection of nigrostriatal neurons against MPTP-induced neurodegeneration that was abrogated by depletion of donor T cells. Such vaccine treatment strategies may provide benefit for Parkinson's disease.

Advances in neuroimaging for HIV-1 associated neurological dysfunction: clues to the diagnosis, pathogenesis and therapeutic monitoring.

Persons with advanced human immunodeficiency virus type one (HIV-1) infection seek medical advice for a wide range of neurological disorders including, but not limited to, peripheral neuropathy, toxoplasmosis, cryptococcal meningitis, cytomegalovirus retinitis progressive multifocal leukoencephalopathy, lymphoma and dementia. The diagnosis of HIV-1-associated dementia (HAD) induced as a direct consequence of HIV infection of the brain comes commonly by exclusion. Diagnostic decisions can often be clouded by concomitant depression, motor impairments, and lethargy that follow debilitating immune suppression and weight loss. Indeed, cognitive, motor and behavior abnormalities underlie a variety of neurological dysfunctions associated with advanced HIV-1 infection. Thus, even combinations of clinical, laboratory and neuroimaging tests [for example, magnetic resonance imaging (MRI), computed tomography (CT), single photon emission computed tomography (SPECT) and positron emission tomography (PET)] often fail to provide conclusive diagnostic information. Nonetheless, the recent development of quantitative MR spectroscopic imaging has improved diagnostic possibilities for HAD. We are pleased to discuss these developments as well as taking a forward look into what will soon be made available to improve neuroimaging diagnostic precision. New MR and SPECT testing are being developed in our laboratories and elsewhere both for animal model systems and in humans with HIV-1 disease. Such tests can facilitate dynamic measures of HIV-1 neuropathogenesis providing information for disease events that even 2 years ago were unattainable.