Results from two major projects were summarized: 1) Development of an inflammation-associated two-hit PD model After a single intra-peritoneal injection (i.p.) of LPS (1 mg/kg) in 7 month-old male a-synuclein over-expressing mice (Tg mice) and wild type controls (WT mice), delayed, progressive degeneration of nigral DA neurons, as measured by decreases in the number of tyrosine hydroxylase immuno-reactive (TH-IR) neurons, was observed in Tg mice but not in WT mice. At 5 months after LPS injection, Tg mice lost 58% of nigral DA neurons, and their striatal TH levels (at the terminals of DA neuron projection) were reduced by 46%. In contrast, neither nigral DA neurons nor striatal TH levels were altered significantly in LPS-injected WT mice and phosphate buffered saline (PBS)-injected Tg mice compared with PBS-injected WT mice. These results demonstrate synergistic neurotoxicity of LPS treatment and a-synuclein overexpression and strongly indicate gene-environment interactions. The relative selectivity of nigral neuro-degeneration was assessed by double-label immunofluorescence. The number of nigral DA neurons was decreased by 52% in LPS-injected Tg mice, whereas non-DA neurons were relatively spared with only a 9.2% reductiona pattern that is consistent with the neuronal loss observed in PD patients. Collectively, this two-hit PD model reproduced the signature lesion of PD by its chronic, progressive and relatively selective degeneration of DA neurons in the SN. In addition to developing delayed, progressive neuro-degeneration, LPS-injected Tg mice also displayed a-synuclein-related pathology 5 months after treatment as shown by a 25% increase in whole brain levels of a-synuclein compared to PBS-injected Tg mice. We therefore proceeded to characterize these changes in a-synuclein. Sequential extraction using buffers with increasing solubilization strengths identified highly insoluble a-synuclein in the midbrain fractions of Tg mice 5 months after LPS injection. By contrast, a-synuclein from the midbrain fractions of PBS-injected Tg mice and age-matched WT mice injected with either PBS or LPS remained soluble. Double-label immunofluorescence revealed accumulation of a-synucleinpositive aggregates in perinuclear compartments of TH-IR neurons in the SN of LPS-injected Tg mice. LPS-injected Tg mice also had enhanced nitrated human a-synuclein accumulated in neurons to form cytoplasmic inclusions compared with PBS-injected Tg mice. Together, these findings indicate that LPS-induced neuro-inflammation in this two-hit model accelerates a-synuclein accumulation, aggregation and nitration. 2) Development of novel therapeutic drug for treatementof Parkinson's disease Mechanistic studies from our laboratory demonstrated the critical role of microglial activation in inflammation-mediated neuro-degeneration in PD and may also potentially contribute to the pathogenesis of other neuro-degenerative diseases. In support of this finding, epidemiological reports indicate that frequent use of the non-steroidal anti-inflammatory drug (NSAIDs) Ibuprofen is associated with a lower risk for PD. Nonetheless, given the failure of recent clinical trials, the potential of NSAIDs for the treatment of PD remains unclear. Most NSAIDs are designed to target a limited number of pro-inflammatory factors released from immune cells under inflammatory conditions. For example, COX-2 inhibitors mainly reduce the production of prostaglandins, without affecting other factors. This narrow spectrum of action limits the efficacy of the agent as a general anti-inflammatory drug. With this in mind, our laboratory has focused on discovering a novel class of anti-inflammatory drugs for the treatment of PD. Unlike most NSAIDs, our strategy targets upstream neuro-inflammatory signaling by inhibiting microglial NOX2,which in turn reduces superoxide production and over-activation of microglia and thereby reducing the release of most pro-inflammatory factors. This novel class of anti-inflammatory drugs is more efficacious than most of the conventional regimens and thus has received wide attention. Recent studies in this line of approach are highlighted below. Post-treatment with sub-picomolar-acting compounds exhibits neuro-protection While evaluating the dose-related neuro-protective efficacies of some anti-inflammatory compounds we made a fortuitous discovery that some compounds have activities at sub-picomolar concentrations. Specifically, we found that both naloxone and dextromethorphan display anti-inflammatory and neuro-protective effects in neuron-glia cultures at the concentration of 10-13 or 10-14 M. The sub-picomolar acting research is novel and important as a new avenue for therapy, because the safety profile is greatly improved and there is a distinct advantage using minute amounts of drugs. Over the last year we have made significant progress in discovering that the commonly used NOX2 inhibitor diphenylene-iodonium (DPI) also exhibits activity at sub-picomolar concentrations and shows great promise as a potential therapy for PD. In addition, we have gone to great efforts to further understand the mechanism of these sub-picomolar-acting compounds.

Project Start
Project End
Budget Start
Budget End
Support Year
17
Fiscal Year
2013
Total Cost
$2,104,992
Indirect Cost
City
State
Country
Zip Code
Wang, Qingshan; Chu, Chun-Hsien; Oyarzabal, Esteban et al. (2014) Subpicomolar diphenyleneiodonium inhibits microglial NADPH oxidase with high specificity and shows great potential as a therapeutic agent for neurodegenerative diseases. Glia 62:2034-43
Lee, Sheng-Yu; Chen, Shiou-Lan; Chang, Yun-Hsuan et al. (2014) The effects of add-on low-dose memantine on cytokine levels in bipolar II depression: a 12-week double-blind, randomized controlled trial. J Clin Psychopharmacol 34:337-43
Zhang, Wei; Yan, Zhao-fen; Gao, Jun-hua et al. (2014) Role and mechanism of microglial activation in iron-induced selective and progressive dopaminergic neurodegeneration. Mol Neurobiol 49:1153-65
Chen, Shiou-Lan; Lee, Sheng-Yu; Chang, Yun-Hsuan et al. (2014) The BDNF Val66Met polymorphism and plasma brain-derived neurotrophic factor levels in Han Chinese patients with bipolar disorder and schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 51:99-104
Lee, Sheng-Yu; Chen, Shiou-Lan; Chang, Yun-Hsuan et al. (2014) Genotype variant associated with add-on memantine in bipolar II disorder. Int J Neuropsychopharmacol 17:189-97
Kumar, Ashutosh; Chen, Shih-Heng; Kadiiska, Maria B et al. (2014) Inducible nitric oxide synthase is key to peroxynitrite-mediated, LPS-induced protein radical formation in murine microglial BV2 cells. Free Radic Biol Med 73:51-9
Zhou, Hui; Liao, Jieying; Aloor, Jim et al. (2013) CD11b/CD18 (Mac-1) is a novel surface receptor for extracellular double-stranded RNA to mediate cellular inflammatory responses. J Immunol 190:115-25
Lee, Sheng-Yu; Chen, Shiou-Lan; Chang, Yun-Hsuan et al. (2013) Add-on memantine to valproate treatment increased HDL-C in bipolar II disorder. J Psychiatr Res 47:1343-8
Lu, Tsun-Jung; Lu, Ru-Band; Hong, Jau-Shyong et al. (2013) Impairment of an electroconvulsive stimulus on reconsolidation of memories established by conditioning. Chin J Physiol 56:44-51
Lee, Sheng-Yu; Chen, Shiou-Lan; Chang, Yun-Hsuan et al. (2013) Inflammation's Association with Metabolic Profiles before and after a Twelve-Week Clinical Trial in Drug-Naive Patients with Bipolar II Disorder. PLoS One 8:e66847

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