Progressive Model Of Parkinson's Disease Research Articles

Microglia, inflammation and gut microbiota responses in a progressive monkey model of Parkinson's disease: A case series

Inflammation has been linked to the development of nonmotor symptoms in Parkinson's disease (PD), which greatly impact patients' quality of life and can often precede motor symptoms. Suitable animal models are critical for our understanding of the mechanisms underlying disease and the associated prodromal disturbances. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkey model is commonly seen as a “gold standard” model that closely mimics the clinical motor symptoms and the nigrostriatal dopaminergic loss of PD, however MPTP toxicity extends to other nondopaminergic regions. Yet, there are limited reports monitoring the MPTP-induced progressive central and peripheral inflammation as well as other nonmotor symptoms such as gastrointestinal function and microbiota. We report 5 cases of progressive parkinsonism in non-human primates to gain a broader understanding of MPTP-induced central and peripheral inflammatory dysfunction to understand the potential role of inflammation in prodromal/pre-motor features of PD-like degeneration. We measured inflammatory proteins in plasma and CSF and performed [18F]FEPPA PET scans to evaluate translocator proteins (TSPO) or microglial activation. Monkeys were also evaluated for working memory and executive function using various behavior tasks and for gastrointestinal hyperpermeability and microbiota composition. Additionally, monkeys were treated with a novel TNF inhibitor XPro1595 (10 mg/kg, n = 3) or vehicle (n = 2) every three days starting 11 weeks after the initiation of MPTP to determine whether XPro1595 would alter inflammation and microglial behavior in a progressive model of PD. The case studies revealed that earlier and robust [18F]FEPPA PET signals resulted in earlier and more severe parkinsonism, which was seen in male cases compared to female cases. Potential other sex differences were observed in circulating inflammation, microbiota diversity and their metabolites. Additional studies with larger group sizes of both sexes would enable confirmation and extension of these findings. If these findings reflect potential differences in humans, these sex differences have significant implications for therapeutic development of inflammatory targets in the clinic.

Changes in thalamic dopamine innervation in a progressive Parkinson's disease model in monkeys.

BackgroundDopamine loss beyond the mesostriatal system might be relevant in pathogenic mechanisms and some clinical manifestations in PD. The primate thalamus is densely and heterogeneously innervated with dopaminergic axons, most of which express the dopamine transporter, as does the nigrostriatal system. We hypothesized that dopamine depletion may be present in the thalamus of the parkinsonian brain and set out to ascertain possible regional differences.MethodsThe toxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine was administered to adult macaque monkeys using a slow intoxication protocol. The treated macaques were classified into 2 groups according to their motor status: nonsymptomatic and parkinsonian. Dopamine innervation was studied with immunohistochemistry for the dopamine transporter. Topographic maps of the dopamine transporter‐immunoreactive axon distribution were generated and the total length and length density of these axons stereologically estimated using a 3‐dimensional fractionator.ResultsParkinsonian macaques exhibited lower dopamine transporter‐immunoreactive axon length density than controls in mediodorsal and centromedian‐parafascicular nuclei. Dopamine denervation in the mediodorsal nucleus was already noticeable in nonsymptomatic macaques and was even greater in parkinsonian macaques. Reticular nucleus dopamine transporter‐immunoreactive axon length density presented an inverse pattern, increasing progressively to the maximum density seen in parkinsonian macaques. No changes were observed in ventral thalamic nuclei. Dopamine transporter‐immunoreactive axon maps supported the quantitative findings.ConclusionsChanges in the dopamine innervation of various thalamic nuclei are heterogeneous and start in the premotor parkinsonian stage. These changes may be involved in some poorly understood nonmotor manifestations of PD. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Genetic suppression of IKK2/NF-κB in astrocytes inhibits neuroinflammation and reduces neuronal loss in the MPTP-Probenecid model of Parkinson's disease.

Neuroinflammatory activation of glia is considered a pathological hallmark of Parkinson's disease (PD) and is seen in both human PD patients and in animal models of PD; however, the relative contributions of these cell types, especially astrocytes, to the progression of disease is not fully understood. The transcription factor, nuclear factor kappa B (NFκB), is an important regulator of inflammatory gene expression in glia and is activated by multiple cellular stress signals through the kinase complex, IKK2. We sought to determine the role of NFκB in modulating inflammatory activation of astrocytes in a model of PD by generating a conditional knockout mouse (hGfapcre/Ikbk2F/F) in which IKK2 is specifically deleted in astrocytes. Measurements of IKK2 revealed a 70% deletion rate of IKK2 within astrocytes, as compared to littermate controls (Ikbk2F/F). Use of this mouse in a subacute, progressive model of PD through exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTPp) revealed significant protection in exposed mice to direct and progressive loss of dopaminergic neurons in the substantia nigra (SN). hGfapcre/Ikbk2F/F mice were also protected against MPTPp-induced loss in motor activity, loss of striatal proteins, and genomic alterations in nigral NFκB gene expression, but were not protected from loss of striatal catecholamines. Neuroprotection in hGfapcre/Ikbk2F/F mice was associated with inhibition of MPTPp-induced astrocytic expression of inflammatory genes and protection against nitrosative stress and apoptosis in neurons. These data indicate that deletion of IKK2 within astrocytes is neuroprotective in the MPTPp model of PD and suggests that reactive astrocytes directly contribute the potentiation of dopaminergic pathology.

The Fyn‐dependent voltage‐gated potassium channel Kv1.3 modulates neuroinflammation and neurodegeneration in Parkinson's disease models

A chronic neuroinflammatory event mediated by persistent microglia activation has been well recognized as a major pathophysiological contributor to the progression of neurodegenerative processes in Parkinson's disease (PD). Identification of key targets contributing to sustained microglia activation and the regulation of these targets could provide potential treatments to halt disease progression. In this study, we show that microglial Kv1.3, a voltage‐gated potassium channel, was highly upregulated in aggregated α‐synuclein (αSyn)‐stimulated primary microglia cultures, animal models of PD, as well as in human PD postmortem samples. Importantly, patch‐clamp electrophysiological studies confirm that the observed Kv1.3 upregulation translates to increased Kv1.3 channel activity. We further demonstrate that Fyn, a non‐receptor tyrosine kinase, modulated the transcriptional upregulation of microglial Kv1.3. Using multiple state‐of‐the‐art techniques, including DuoLink PLA technology, we show that Fyn directly binds to Kv1.3 and post‐translationally modified its channel activity. Furthermore, we demonstrate the functional relevance of Kv1.3 with respect to neuroinflammation by using Kv1.3 knockout (KO) microglia and the Kv1.3‐specific pharmacological inhibitor PAP‐1. Kv1.3 KO microglial cells treated with aggregated αSyn produced fewer pro‐inflammatory cytokines. PAP‐1 significantly attenuated aggregated αSyn‐induced inflammation in both a microglial cell line and primary microglia, thus highlighting Kv1.3's importance in inflammation. Oral administration of PAP‐1 significantly inhibited MPTP‐induced neurodegeneration and inflammation in vivo. PAP‐1 also significantly reversed behavioral deficits and dopamine loss in MitoPark mice, a progressive model of PD. Our results collectively show that the Fyn‐dependent Kv1.3 channel plays an important role in inflammation in PD and has potential therapeutic implications.Support or Funding InformationES026892, NS088206, NS100090, Llyod ChairThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

IGF-1 protects dopamine neurons against oxidative stress: association with changes in phosphokinases.

Insulin-like growth factor-1 (IGF-1) is an endogenous peptide transported across the blood brain barrier that is protective in several brain injury models, including an acute animal model of Parkinson's disease (PD). Motor deficits in PD are due largely to the progressive loss of nigrostriatal dopaminergic neurons. Thus, we examined the neuroprotective potential of IGF-1 in a progressive model of dopamine deficiency in which 6-hydroxydopamine (6-OHDA) is infused into the striatum. Rats received intrastriatal IGF-1 (5 or 50µg) 6h prior to infusion of 4µg 6-OHDA into the same site and were euthanized 1 or 4weeks later. Both concentrations of IGF-1 protected tyrosine hydroxylase (TH) immunoreactive terminals in striatum at 4weeks but not at 1week, indicating that IGF-induced restoration of the dopaminergic phenotype occurred over several weeks. TH-immunoreactive cell loss was only attenuated with 50µg IGF-1. We then examined the effect of striatal IGF-1 on the Ras/ERK1/2 and PI3K/Akt pathways to ascertain whether their activation correlated with IGF-1-induced protection. Striatal and nigral levels of phospho-ERK1/2 were maximal 6h after IGF-1 infusion and, with the exception of an increase in nigral pERK2 at 48h, returned to basal levels by 7days. Phospho-Akt (Ser473) was elevated 6-24h post-IGF-1 infusion in both striatum and substantia nigra concomitant with inhibition of pro-death GSK-3β, a downstream target of Akt. These results suggest that IGF-1 can protect the nigrostriatal pathway in a progressive PD model and that this protection is preceded by activation of key pro-survival signaling cascades.

The Progressive BSSG Rat Model of Parkinson's: Recapitulating Multiple Key Features of the Human Disease.

The development of effective neuroprotective therapies for Parkinson's disease (PD) has been severely hindered by the notable lack of an appropriate animal model for preclinical screening. Indeed, most models currently available are either acute in nature or fail to recapitulate all characteristic features of the disease. Here, we present a novel progressive model of PD, with behavioural and cellular features that closely approximate those observed in patients. Chronic exposure to dietary phytosterol glucosides has been found to be neurotoxic. When fed to rats, β-sitosterol β-d-glucoside (BSSG) triggers the progressive development of parkinsonism, with clinical signs and histopathology beginning to appear following cessation of exposure to the neurotoxic insult and continuing to develop over several months. Here, we characterize the progressive nature of this model, its non-motor features, the anatomical spread of synucleinopathy, and response to levodopa administration. In Sprague Dawley rats, chronic BSSG feeding for 4 months triggered the progressive development of a parkinsonian phenotype and pathological events that evolved slowly over time, with neuronal loss beginning only after toxin exposure was terminated. At approximately 3 months following initiation of BSSG exposure, animals displayed the early emergence of an olfactory deficit, in the absence of significant dopaminergic nigral cell loss or locomotor deficits. Locomotor deficits developed gradually over time, initially appearing as locomotor asymmetry and developing into akinesia/bradykinesia, which was reversed by levodopa treatment. Late-stage cognitive impairment was observed in the form of spatial working memory deficits, as assessed by the radial arm maze. In addition to the progressive loss of TH+ cells in the substantia nigra, the appearance of proteinase K-resistant intracellular α-synuclein aggregates was also observed to develop progressively, appearing first in the olfactory bulb, then the striatum, the substantia nigra and, finally, hippocampal and cortical regions. The slowly progressive nature of this model, together with its construct, face and predictive validity, make it ideal for the screening of potential neuroprotective therapies for the treatment of PD.

Comparison between α-synuclein wild-type and A53T mutation in a progressive Parkinson's disease model

Background and aimsVector based over-expression of α-synuclein is a newly developed method to establish animal Parkinson's disease (PD) model. In this paper, we inject the rat brain with recombinant adeno-associated virus (rAAV) to express α-synuclein wild-type and A53T mutation, and compared the degeneration of dopaminergic neurons between them. Method and resultsThe rAAV vectors were injected into the substantia nigra pars compacta (SNpc) of rat brain. In different time point, immunohistochemistry was used to detect the expression of α-synuclein. The expression level was lower in the 3rd and 6th week and increased from the 9th week. α-synuclein spread around the neurons in SNpc in the 12th week. The loss of dopaminergic neurons was increasing along the expression of α-synuclein, and damage extent was more serious in the A53T group than the WT group. In the A53T group, there were more insoluble inclusions can be detected, and the phosphorylation of α-synuclein was also higher. ConlusionThe result of comparison between the two types of α-synuclein showed that A53T mutated α-synuclein was more effective to establish PD model, and the model based A53T mutated α-synuclein was a suitable model to early-onset PD.

Rosiglitazone decreases peroxisome proliferator receptor-gamma levels in microglia and inhibits TNF-alpha production: new evidences on neuroprotection in a progressive Parkinson's disease model

Thiazolidinedione (TZD) class of peroxisome proliferator receptor gamma (PPAR-γ) agonists display neuroprotective effects in experimental Parkinson's disease (PD) models. Neurons and microglia express PPAR-γ, therefore both of them are potential targets for neuroprotection, although the role of each cell type is not clear. Moreover, receptor-dependent as well as receptor-independent mechanisms have been involved. This study further investigated mechanisms of TZD-mediated neuroprotection in PD. We investigated the rosiglitazone effect in the progressive MPTP/probenecid (MPTPp) model of PD. C57BL/6J mice received MPTP (25 mg/kg) plus probenecid (100 mg/kg) twice per week for 5 weeks. Rosiglitazone (10 mg/kg) was given daily until sacrifice, starting on the fourth week of MPTPp treatment, in presence of an ongoing neurodegeneration with microgliosis. Changes in PPAR-γ levels were measured by immunofluorescence and confocal microscopy in tyrosine hydroxylase (TH)-positive neurons and CD11b-positive microglia of the substantia nigra pars compacta (SNc). Chronic MPTPp treatment induced a PPAR-γ overexpression in both TH-positive neurons and microglia (139.9% and 121.7% over vehicle, respectively). Rosiglitazone administration to MPTPp-treated mice, reverted PPAR-γ overexpression in microglia without affecting TH-positive neurons. Thereafter, changes in CD11b and tumor necrosis factor α (TNF-α) immunoreactivity in microglia were evaluated in the SNc. MPTPp progressively increased CD11b immunoreactivity, conferring to microglia a highly activated morphology. Moreover, TNF-α levels were increased (457.38% over vehicle) after MPTPp. Rosiglitazone administration counteracted the increase in CD11b immunoreactivity caused by MPTPp. Moreover, rosiglitazone reverted TNF-α expression to control levels. Nigrostriatal degeneration was assessed by high pressure liquid chromatography (HPLC) measurement of striatal dopamine, and counting of TH-positive neurons in the SNc. MPTPp treatment caused a severe decline of striatal dopamine and a partial degeneration of the SNc. Rosiglitazone arrested the degenerative process in both areas. Results suggest that PPAR-γ expression in microglia and TNF-α production by these cells are crucial changes by which rosiglitazone exerts neuroprotection in PD.