Joel S. Perlmutter, M.D. - US grants

This is a Shannon Award providing partial support for research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. Further scientific data for the CRISP System are unavailable at this time.

Dystonia is a syndrome of intermittent or sustained involuntary muscle contractions that frequently causes twisting and repetitive movements producing abnormal postures. These involuntary movements can affect many parts of the body (generalized) or affect more limited areas (focal) such as the eyelids in blepharospasm or the hand and arm in hand cramp. The pathophysiology of these syndromes remain unclear but a variety of clues suggest abnormalities of central dopaminergic pathways. We hypothesize that patients with idiopathic focal dystonia have upregulation of striatal D2 receptors and that this upregulation is somatotopically organized depending upon the body part involved. We will test this hypothesis by measuring radioligand binding in vivo with positron emission tomography (PET) and [18F]spiperone (or the more specific radioligand [18F](N-methyl)benperidol, if this radioligand is available at the beginning of these studies) in patients with blepharospasm, hand cramp and age-matched normals. We will analyze the data to determine whether either group of patients has an elevation of receptor binding and also determine whether the location of maximal radioligand binding differs between patients with blepharospasm and hand cramp. These data should provide important information about the pathophysiology underlying these focal dystonias and lead to new avenues of investigation regarding pathophysiology and treatment of the idiopathic dystonias.

DESCRIPTION: Dystonia is a syndrome of intermittent or sustained involuntary muscle contractions that frequently causes twisting and repetitive movements producing abnormal postures. These involuntary movements can affect many parts of the body (generalized) or affect more limited areas such as the focal dystonias. The pathophysiology of these syndromes remains unclear but a variety of clues suggest abnormalities of central dopaminergic pathways. We now have evidence that there is an abnormality of [18F]spiperone ([18F]SP) binding in the putamen, one of the key basal ganglia nuclei involved in motor control. [18F]SP, however, binds to both D2-like dopaminergic receptors and to S2 receptors in primate striatum. The objective of this research proposal is to determine whether patients with idiopathic focal dystonias have alterations in putaminal D2 dopaminergic receptors. Specifically, we hypothesize that patients with idiopathic focal dystonia have abnormal binding of putaminal D2-specific receptors and that receptor binding is somatotopically organized depending upon the body part involved. Additionally, we hypothesize that a genetic abnormality coding for a dopamine receptor may permit the development of these clinical manifestations. To test these hypotheses, we will measure dopamine receptor binding in vivo in patients with dystonias affecting their face (cranial dystonia) and the hand (hand cramp) as well as normals using positron emission tomography and a new dopamine D2 receptor radioligand, [18F]NMB. We will use magnetic resonance imaging to assist with precise localization of radioactive uptake in the putamen. We also will use a powerful new approach to analysis of genetic information called cladistics-based evolutionary analysis of the haplotypes of the DRD2 locus to try to identify the genetic abnormality that may predispose one to develop dystonia. These studies in addition to providing new insight into the pathophysiology of idiopathic dystonia also will help to understand and eventually treat conditions such as drug-induced involuntary movements produced by anti-psychotics as well as provide a better understanding of the function of the basal ganglia in the control of normal and abnormal movements.

DESCRIPTION (provided by applicant): Deep brain stimulation (DBS) of the subthalamic nuclei (STN) may provide substantial reduction of symptoms in people with Parkinson disease (PD) and DBS of the thalamic ventral intermediate nucleus (VIM) markedly reduces tremor in people with disorders such as essential tremor (ET). Increasing data also indicates that STN DBS in PD may produce unwanted cognitive impairments, such as impairments of spatial delayed recall or response inhibition. Despite these dramatic clinical effects, the precise mechanism of action of DBS remains unclear. Recent studies, including several from this lab, indicate that DBS produces a net increase in neuronal output from the site of stimulation either the STN in PD or VIM in ET, and there may be important differences in the effects of STN on the left and right sides of the brain. Nevertheless, how this action and its asymmetry provide clinical benefit while simultaneously interfering with selected cognitive function remains unknown. We hypothesize that STN and VIM DBS provide motor benefit by altering function of specific motor brain regions, whereas, STN DBS impairs cognitive skills by altering function of selected prefrontal regions. Further, we propose that there are substantial differences between left and right-sided STN stimulation on aspects of motor and cognitive function. We will test these specific hypotheses using PET to measure brain blood flow responses to varying levels of STN or VIM stimulation in people with PD or ET and then correlate these PET responses with cognitive or motor responses to DBS in the same subjects. These studies have the potential to reveal valuable insights into the mechanism of DBS and also into the pathophysiology of these diseases and their clinical manifestations. For example, we may identify specific brain pathways that mediate cognitive impairment from STN DBS that are distinct from those that mediate motor benefit. This could directly lead to designing new strategies to maximize motor benefit and minimize cognitive impairments. We also have the potential to provide a rationale for investigating new sites for DBS that may be more accessible than those currently used. This innovative study brings together rigorous, carefully controlled PET investigations with quantified motor and cognitive behavioral measures.

DESCRIPTION (provided by applicant): Parkinson disease (PD) affects nearly one million people in North America. Current treatment provides only symptomatic relief, but no proven intervention slows its progression. Such an intervention should be administered early in the course of the disease to minimize progressive neuronal injury, disability and its substantial economic impact. A new class of potent antioxidants, the carboxyfullerenes, has the potential to slow the progression of the disease and promote recovery since these drugs have produced significant protection from neurotoxic injuries on dopaminergic cells in vitro and recovery from nigrostriatal injury in rodent models of PD. Furthermore, these compounds appear to have minimal in vivo toxicity and can be administered systemically making them outstanding candidates for human therapy. To translate these basic discoveries into treatment, we must do the next critical step; evaluate efficacy and safety in nonhuman primates. This is essential since dosing can be markedly different between rodents and primates. Finding the proper dose for human trials may save millions of dollars on studies done with the wrong dose. To do this, we propose using unilateral intracarotid (i.c.) infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in monkeys to produce ipsilateral nigrostriatal injury and contralateral behavioral abnormalities. We hypothesize that systemic administration of carboxyfullerenes will prevent progression from early signs of nigrostriatal injury to chronic parkinsonism, reduce the severity of subsequent parkinsonism and induce recovery from neuronal injury. The C3 carboxyfullerene derivative will be chronically administered for two months in three doses to determine the most effective dose. Effectiveness will be quantified in vivo with positron emission tomographic measures of 18 Fluoro-L-DOPA [18FDOPA] uptake, behavioral measures of motor function and in vitro measures of nigrostriatal neurons with tyrosine hydroxylase immunoreactivity, cells counts and dopamine content. These studies represent the first attempt to treat nigrostriatal injury in primates with the antioxidant buckminsterfullerenes. Further, this multidisciplinary strategy provides the basis for testing other agents that may prevent progression or restore function in parkinsonism. If this strategy works, these results will provide the preliminary data for a proper trial of these promising drugs in humans.

DESCRIPTION (provided by applicant): Parkinson's disease (PD) is a neurodegenerative condition that causes substantial disability in the nearly 1 million affected people in North America. Development of a treatment that could halt or slow its progression has the potential to minimize progressive neuronal injury, thereby reducing subsequent disability and the substantial economic impact of this disease. C3, a carboxyfullerene, is a newly synthesized potent antioxidant and superoxide dismutase mimetic. Preliminary studies demonstrate that C3 provides significant protection of dopamine neurons from neurotoxic injuries in vitro and in vivo. Thus, C3 has the potential to slow progression and promote neuronal recovery in human PD. C3 also appears to have minimal in vivo toxicity and can be given systemically making it an outstanding candidate for treating people. To translate these basic discoveries into human therapy, we must evaluate safety, efficacy and dosing in monkeys since results from rodent studies may not be directly applicable for development of a treatment strategy for people. Finding the proper dose in nonhuman primates may save millions of dollars in subsequent clinical trials. We will give MPTP via unilateral intracarotid infusion to selectively damage nigrostriatal neurons and produce contralateral motor deficits. We hypothesize that subcutaneous administration of C3 will reduce the severity of subsequent parkinsonism and damage to nigrostriatal dopaminergic neurons. In this project, we will determine the most effective dose of C3. Efficacy will be quantified with behavioral measures of motor function, with in vivo measures of nigrostriatal neurons with high resolution MicroPET and [11C]DTBZ (a marker of vesicular monoamine uptake transporter - VMAT2), and with ex vivo measures of nigrostriatal dopaminergic neurons with tyrosine hydroxylase immunoreactivity, cells counts and dopamine content. This multidisciplinary strategy combines state-of-the-art neuroimaging and quantitative behavioral measures to determine whether the carboxyfullerene C3 has the potential in a primate model of PD to prevent progression, restore function or both. These studies will provide a solid foundation for a clinical trial in humans with C3 and can potentially reduce the suffering and economic burden of PD.

[unreadable] DESCRIPTION (provided by applicant): Parkinson disease (PD) affects more than one million people in North America, and no treatment has been proven to slow progression. We must have a validated biomarker of PD progression to permit testing and development of any disease modifying therapy. Without this, we may not be able to reach our ultimate goal of retarding the progression or reversing the inexorable decline of PD. Currently, clinically-based measures and other biomarkers PD progression have major confounds that limit their utility. Neuroimaging biomarkers have potential to provide unbiased measurements of PD progression. However, multiple issues complicate interpretation of currently available SPECT or PET markers and have led to conflicting findings between neuroimaging-based and clincally-based measures of disease severity in several large studies of PD. One key issue is whether any of the currently-available PET markers truly reflects the reduction of the number of nigrostriatal neurons. We propose to compare two different PET tracers in MPTP-treated monkeys: [11C]DTBZ (a vesicular monoamine transporter type 2 [VMAT2] marker) and [11C]CFT (a dopamine transport [DAT] marker), and determine which one provides the most faithful reflection of the decrease in the number of nigrostriatal neurons. PET measurements will be compared to stereological counts of cell bodies of tyrosine hydroxylase (TH) immunostaining neurons in nigra; TH-staining fibers of these neurons in striatum, quantitative in vitro autoradiography of VMAT2 and DAT in striatum, striatal dopamine content measured with high performance liquid chromotography and behavioral ratings of parkinsonism that have been validated for monkeys. Prior to MPTP, each animal will have 3 behavioral measures collected and 2 PET measures with each radiotracer. We previously demonstrated that animals will have stable clinical parkinsonism 2 months after intracarotid MPTP. We will do repeated behavioral measures and then PET with the 2 tracers just prior to euthanasia. In vitro measures will be done on fixed tissue from midbrain and fresh frozen tissue from striatum. We then will determine which PET radiotracer provides the best correlation with the change dopaminergic neurons or behavioral changes determined by ratings scales. This study will provide a critical step in validation of a neuroimaging biomarker of PD progression. We need such a validated biomarker to permit testing of any disease modifying intervention. PUBLIC HEALTH RELEVANCE: Parkinson disease (PD) affects more than one million people in North America, and no treatment has been proven to slow progression. To develop such a treatment, it is necessary to have an objective measure of disease progression. This application proposes to develop and validate a neuroimaging biomarker to measure PD progression; a critical step needed to determine the efficacy of any newly proposed intervention. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Deep brain stimulation (DBS) of the subthalamic nucleus (STN) dramatically improves motor function and quality of life in PD yet may alter cognitive skills and mood (Progress Report). Our studies and others suggest that functional organization of basal ganglia-thalamocortical (BGTC) circuits and their course through STN underlies these effects. We hypothesize based on preliminary data that DBS focused in ventral STN (V-STN) selectively alters cognition and mood whereas motor benefit is widely distributed. We propose that this functional organization of STN will produce downstream effects in relevant pathways. In people with PD, we will compare the effects of unilateral monopolar DBS through selected V-STN and dorsal STN (D-STN) contacts on quantified motor, cognitive, and mood function with DBS-induced rCBF responses and presurgical MRI-based resting state functional connectivity (rs-fcMRI) networks. We found that rs-fcMRI identified key cortical and BGTC networks that are disrupted in PD and can provide an anchor for interpretation of downstream effects seen with rCBF responses. These studies have great potential to extend our understanding of the functional anatomy of the STN by delineating its role in motor, cognitive and mood behaviors in PD. These studies could reveal valuable insights into the clinical action of DBS and the pathophysiology of cognitive, mood and motor symptoms of PD. However, the importance of these studies goes beyond the specifics of DBS treatment for PD. We can take this unique opportunity to investigate the function of selected brain pathways in the region of the STN and how they affect cognitive, mood and motor function. Such basic observations have importance for understanding STN function and how impairments lead to disabilities in other basal ganglia disorders. These studies also have the potential to help refine DBS targeting, inform future development of new electrode design to shape current spread and improve programming strategies for optimal clinical benefit from STN DBS.

? DESCRIPTION (provided by applicant): Parkinson disease (PD) produces progressive motor and cognitive impairments leading to dementia in ~75% of patients after 10 years. Development of therapies to slow PD progression requires validated biomarkers of pathologic processes and that predict progression. Such biomarkers could reflect regional pathophysiology and disruption of local or widely distributed networks that cause behavioral deficits. This project focuses on cross- sectional and longitudinal relationships among proteinopathy, cholinergic deficits, disruption of functional connectivity networks and behavior. We will build upon our findings in a single site longitudinal cohort of 270 people with PD and controls to extend and expand a multimodal approach to determine the time course of biomarker changes that correspond with and predict cognitive decline in PD. We have the potential to provide in vivo neuroimaging and CSF biomarkers of pathology and pathophysiology that could independently, or in combination, predict clinical manifestations in PD. We will combine PiB (an A? amyloid imaging agent) and VAT (a vesicular cholinergic transport ligand) PET, CSF protein levels and resting state functional connectivity analyses (rs-fcMRI using advanced analysis methods) measures of pathophysiology with sophisticated behavioral measures focusing on cognition and postmortem brain analyses including quantification of pathologic proteins. We will determine the relationships between PET biomarkers and CSF proteinopathy, and compare these to clinical manifestations. Rs-fcMRI, as a measure of brain function, will link brain pathology and neurochemistry with the associated clinical manifestations. In this manner, we will develop a strong mechanistic understanding of changes in these neuroimaging and CSF biomarkers and how this relates to cognitive decline and dementia in PD. This project holds great promise for identifying pathophysiological biomarkers for prediction of PD progression, patient stratification for trials and evaluation of new treatments.

DESCRIPTION (provided by applicant): Parkinson disease (PD) affects more than one million people in North America, and no treatment has been proven to slow progression. To develop and test new interventions to slow disease progression, we must have validated biomarkers that reflect reversible or modifiable pathologic processes. Increasing evidence suggests selective vulnerability to different parts of nigrostriatal dopaminergic neurons; thus biomarkers that reflec different aspects of pathologic processes may be critical to develop these new therapies. Our initial studies in the first 3 years of this proposal have clarified how neuroimaging biomarkers reflect underlying pathologic processes of nigrostriatal neurons. We have data comparing neuroimaging measures with in vitro measures in nonhuman primates two months after giving different doses of unilateral intracarotid MPTP indicating that striatal uptake of [18F]FD (primarily reflecting decarboxylase activity), [11C]CFT (a dopamine transport marker, DAT) and [11C]DTBZ (a vesicular monoamine transporter type 2) reflect striatal dopamine content but only reflect nigral DA cell bodies if the loss of nigral neurons does not exceed 50%. We also demonstrated with in vitro quantitative autoradiography that DAT and VMAT2 presynaptic sites do not differentially regulate as the number nigrostriatal neurons decreases. PET measures of striatal uptake of FD, DTBZ and CFT also change nearly identifically as the number of nigrostriatal neurons decreases. Our results reveal that terminal fields (striatal DA and the PET measures) have greater loss than nigral cell bodies at 2 months post MPTP. We also have preliminary data that MR-based measures of midbrain mean diffusivity correlate with stereologic counts of nigrostriatal dopaminergic neurons. Some initial studies suggest that probablistic tract tracing may be able to quantify nigrostriatal axons. Together these findings set the stage for the studies proposed in this renewal. We will test the hypothesis that these newly validated neuroimaging biomarkers can detect time-dependent changes in different components of nigrostriatal dopaminergic neurons and validate these measures against in vitro measures including stereologic counts of tyrosine hydroxylase (TH) immunostained cell bodies in nigral, TH-stained striatal fibers, DAT immunostained striatal fibers, striatal dopamine content, quantitative autoradiography of DAT and VMAT2 sites in striatum and clinical ratings of motor behaviors using validated rating scales. In addition, we will test the hypothesis that acute or chronic administration of levodopa or the dopamine agonist pramipexole may alter selected neuroimaging biomarkers. This study will provide the critical tools for targeting the relevant pathologic sites for testing new therapies for PD.

ABSTRACT Multiple neurologic and psychiatric disorders including Parkinson disease (PD), Huntingon disease (HD), dystonia and schizophrenia involve dopaminergic (DA) pathways as part of pathophysiology or treatment. Changes in function of nigrostriatal pathways may reflect either presynaptic or postsynaptic effects. Most previous studies focused on presynaptic changes. This proposal focuses on phosphodiesterases (PDEs) that control signal transduction of both families of DA receptors (D1-like and D2-like). PDE10A, the PDE subtype restricted to striatal medium spiny neurons (MSNs) and is expressed in direct (mosty D1-mediated) and indirect pathway neurons (mostly D2-mediated). PET ligands for PDE10A could facilitate study of pathophysiology, disease progression or target engagement for diseases with striatal pathologies such as PD or HD. However, the interactions among presynaptic nigrostriatal neurons, DA receptors, behavior and PDE10A remain unknown. Failure to understand these relationships led to confusion about interpretation of clinical studies using presynaptic molecular DA biomarkers. Molecular imaging measures also may be altered by either acute or chronic drug exposures, thus investigation of those potential effects also will permit unabmiguous interpretation of human studies. This proposal will help prevent such confusion by directly determining the effects of nigrostriatal injury on striatal PDE10A, comparing with presynaptic measures, D1-like and D2-like DA receptors, other striatal neurotransmitters and motor behavior in nonhuman primates (NHPs). We will leverage previously collected tissues from NHPs that have been treated with varying doses of intracarotid (ic) MPTP that causes graded degrees of nigrostriatal injury. We also will study new NHPs to determine the relationships between in vivo PET measures of PDE10A with other presynaptic and postsynaptic biomarkers. We will use two different PET radioligands for PDE10A that have different tracer kinetic properties. Finally, we will determine the effects of acute or chronic drugs on in vivo PDE10A in striatum since drug effects can be a major confound in human imaging studies, particularly of dopaminergic pathways. These proposed studies will permit unambiguous interpretation of PDE10A PET radioligands to investigate relevant pathophysiologies or provide measures of target engagement of new therapies for PD, HD and possibly psychosis.

ABSTRACT. Parkinson disease (PD) causes motor and nonmotor manifestations. Underlying pathology includes abnormal deposition of ?-synuclein (?-syn) starting in caudal brainstem (as well as olfactory tubercle and medial temporal areas) and then spreads to more rostral brainstem and cortical areas. Initial motor manifestations likely reflect degeneration to the nigrostriatal dopaminergic pathway but cortical dysfunction leading to nonmotor and some motor manifestations may reflect direct ?-syn involvement, neurotransmitter deficiencies due to loss of projecting brainstem nuclei or secondary dysfunction of cortical or subcortical networks. Currently, no treatment delays the relentless progression of PD. We have preliminary data (neuroinflammation, increased reactive oxygen species) after nigrostriatal injury in nonhuman primates (NHPs) that suggests that cortical dysfunction may occur from retrograde degeneration along cortico-striatal neurons. Here we will test whether an anti-inflammatory compound, synoxizyme (previously called carboxyfullerene or C3), will reduce the observed neuroinflammation, and prevent retrograde cortical injury as a potential mechanism which could contribute to disability in people with PD. We will confirm this finding and validate in vivo PET measures of neuroinflammation and reactive oxygen species. We also demonstrated that synoxizyme restores nigrostriatal dysfunction after unilateral internal carotid (ic) infusion of the selective neurotoxin MPTP. Synoxizyme may act through attenuation of neuroinflammation and reduce destructive reactive oxygen species. Another goal of this study is to determine whether our new PET radiotracers can act as targets of engagement for synoxizyme. These highly novel studies will determine whether nigrostriatal injury with MPTP in nonhuman primates leads to cortical dysfunction which could provide the basis for investigations into another mechanism of cortical dysfunction that occurs in people with PD. Furthermore, we will validate new PET measures of neuroinflammation and reactive oxygen species that could be key for such studies. We will determine whether diffusion tensor imaging MR measures of mean diffusivity identify cortical striatal tract dysfunction that could support the notion of retrograde degeneration after nigrostriatal injury. We also will determine whether systemically administered synoxizyme will attenuate the effects of MPTP and whether this corresponds with a reduction in MPTP-induced neuroinflammation and increased reactive oxygen species ? which may be involved in the pathogenesis of human PD. Finally, we will be able to demonstrate whether the PET measures may provide quantification of targets of engagement for synoxizyme, which would be critical information for a subsequent clinical trial in humans of synoxizyme or any other treatment targeting these pathogenic mechanisms in PD or other neurodegenerative conditions.

ABSTRACT This Clinical Core will implement first in human PET imaging with new radiotracers targeting ?-synuclein (?-syn) and 4 repeat tau (4R tau). Radiotracers will be developed pre-clinically in the Med Chem Core and in Projects 1 and 2 focusing on ?-syn and 4R tau, respectively. We will focus ?-syn radiotracers on two synucleinopathies, Parkinson disease (PD) and Multiple Systems Atrophy (MSA), and focus 4R tau radiotracers on two different tauopathies, progressive supranuclear palsy (PSP) and familial frontotemporal dementias (FTD) due to mutation in Microtubule Associated Protein Tau (MAPT) gene. We will draw participants and interact with multiple ongoing clinical cohorts of FTD, PSP, PD and MSA. The Clinical Core functions include interaction with the Executive Committee to determine when to start human studies, coordinate required regulatory activities for radiotracer candidates, carry out early safety assessments including whole body dosimetry studies at Penn; coordinate patient selection criteria, centrally collect and serve all imaging and demographic data, coordinate tracer kinetic methods development and validation for human imaging, and coordinate all data to efficiently enable GO-NOGO decisions for candidate radiotracers. Radiotracers for ?-syn will be tested in two different synucleinopathies, PD and MSA whereas, 4R tau radiotracers will be tested in PSP and FTD patients. As a final check on diagnosis and specificity of candidate radiotracers, we will request all patient participants to permit postmortem brain donation for autoradiography of relevant radiotracers on fresh frozen brain tissues. Additionally, this Core will interact with multiple ongoing studies with cohorts studying PD, MSA, PSP and FTD. Finally, a robust data sharing plan facilitates collaboration and use of support documents and imaging data.