Neuroinflammatory processes in Parkinson's disease

Leucine-rich repeat kinase 2 modulates cyclooxygenase 2 and the inflammatory response in idiopathic and genetic Parkinson's disease

Inflammatory mechanisms are activated in aging and late-onset neurodegenerative diseases, such as Parkinson's disease (PD). Mutations in leucine-rich repeat kinase 2 (LRRK2) contribute to both idiopathic and familial forms of PD. Here, we investigated the involvement of LRRK2 in inflammatory pathways using primary dermal fibroblasts from patients with 2 common mutations in LRRK2 (G2019S and R1441G), idiopathic PD and age-matched healthy individuals. Basal cyclooxygenase (COX)-2 RNA levels were very high in the fibroblasts of all patients. Remarkably, LRRK2 silencing experiments significantly reduced basal COX-2 levels and COX-2 induction after a pro-inflammatory stimulus. Additionally, in samples from patients with the R1441G mutation and with idiopathic PD, we found a prominent cytoplasmic re-distribution of human antigen R, a protein that, among others, stabilizes COX-2 RNA. Furthermore, the response to lipopolysaccharide was defective in these 2 groups, which showed weak induction of pro-inflammatory cytokines and reduced NFκB transcriptional activation. In summary, we describe multiple defects in inflammatory pathways in which LRRK2 appears to be critically involved. Further studies are required to establish the therapeutic implications of inflammatory dysregulation in the pathophysiology of Parkinson's disease.

Phytoestrogens mediated anti-inflammatory effect through suppression of IRF-1 and pSTAT1 expressions in lipopolysaccharide-activated microglia

Microglial activation has been implicated in various neurological disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and HIV encephalopathy. Phytoestrogens have been shown to be neuroprotective in neurotoxicity models; however, their effect on microglia has not been well established. In the current study, we report that the soy phytoestrogens, genistein, daidzein, and coumestrol, decreased nitric oxide (NO) production induced by lipopolysaccharide (LPS) in the rat microglial cell line (HAPI). The levels of inducible NO synthase (iNOS) mRNA and protein expression were also reduced. Transcription factors known to govern iNOS expression including interferon regulatory factor-1 (IRF-1) and phosphorylated STAT1 were down regulated. These observations explain, at least in part, the inhibitory effect of phytoestrogens on NO production. The levels of monocyte chemoattractant protein-1 and interleukin-6 mRNA, proinflammatory chemokine and cytokine associated with various neurological disorders, were also reduced following LPS stimulation when HAPI cells were pretreated with phytoestrogens. Hence, genistein, daidzein, and coumestrol could serve as anti-inflammatory agents and may have beneficial effects in the treatment of neurodegenerative diseases.

Tear levels of tumor necrosis factor-alpha in patients with Parkinson's disease

Neuroinflammatory events mediated by the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) cause progressive neurodegeneration in dopaminergic neurons, and play an important role in the pathogenesis of Parkinson's disease (PD). The purpose of this study was to determine TNF-α levels in tear samples obtained from patients with PD and to analyze the relationship between TNF-α values and PD characteristics. Eighteen patients with PD and 17 healthy control subjects were included in the study. We examined the patient demographics, modified Hoehn and Yahr Staging Scale (mHY) stages, Unified Parkinson's disease rating scale (UPDRS) II and III scores, Mini Mental State Examination (MMSE) scores, and the predominant symptoms. We measured TNF-α using the multiplex immunobead assay in unstimulated tear samples, and determined the Schirmer's test and blink rate for each subject. Tear TNF-α values were significantly higher in patients with PD (196.9 ± 121.2 pg/ml) than in control subjects (110.7 ± 87.2 pg/ml; p=0.02). We identified no relationship between tear TNF-α levels and age, sex, age at onset, PD duration, mHY stages, UPDRS II, UPDRS III, or MMSE scores. The higher TNF-α levels observed in the tears of patients with PD suggests neuroinflammation and TNF-α plays a role in the pathogenesis of PD. Tear TNF-α levels, however, were not related to the duration or severity of PD. Tears are a suitable method for measuring TNF-α levels, and can be used as a diagnostic measure to evaluate biomarkers in PD.

Cellular and molecular mediators of neuroinflammation in the pathogenesis of Parkinson's disease

Neuroinflammation is a host-defense mechanism associated with restoration of normal structure and function of the brain and neutralization of an insult. Increasing neuropathological and biochemical evidence from the brains of individuals with Parkinson's disease (PD) provides strong evidence for activation of neuroinflammatory pathways. Microglia, the resident innate immune cells, may play a major role in the inflammatory process of the diseased brain of patients with PD. Although microglia forms the first line of defense for the neural parenchyma, uncontrolled activation of microglia may directly affect neurons by releasing various molecular mediators such as inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-6, and IL-1β), nitric oxide, prostaglandin E2, and reactive oxygen and nitrogen species. Moreover, recent studies have reported that activated microglia phagocytose not only damaged cell debris but also intact neighboring cells. This phenomenon further supports their active participation in self-enduring neuronal damage cycles. As the relationship between PD and neuroinflammation is being studied, there is a realization that both cellular and molecular mediators are most likely assisting pathological processes leading to disease progression. Here, we discuss mediators of neuroinflammation, which are known activators released from damaged parenchyma of the brain and result in neuronal degeneration in patients with PD.

MMP-3 contributes to nigrostriatal dopaminergic neuronal loss, BBB damage, and neuroinflammation in an MPTP mouse model of Parkinson's disease

The present study examined whether matrix metalloproteinase-3 (MMP-3) participates in the loss of dopaminergic (DA) neurons in the nigrostriatal pathway in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease with blood brain barrier (BBB) damage and infiltration of peripheral immune cells. Tyrosine hydroxylase (TH) immunostaining of brain sections from MPTP-treated mice showed that MPTP induced significant degeneration of nigrostriatal DA neurons. Moreover, FITC-labeled albumin detection and immunostaining revealed that MPTP caused damage to the BBB and increased the number of ED-1- and CD-3-immunopositive cells in the substantia nigra (SN). Genetic ablation of MMP-3 reduced the nigrostriatal DA neuron loss and improved motor function. This neuroprotective effect afforded by MMP-3 deletion was associated with the suppression of BBB disruption and a decrease in the number of ED-1- and CD-3-immunopositive cells in the SN. These data suggest that MMP-3 could play a crucial role in neurodegenerative diseases such as PD in which BBB damage and neuroinflammation are implicated.

Tenuigenin protects dopaminergic neurons from inflammation-mediated damage induced by the lipopolysaccharide

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive death of dopaminergic neurons in the substantia nigra pars compacta (SNpc).

AIMS

To study if tenuigenin (TEN), the main active component of Polygala tenuifolia, can protect dopaminergic neurons from inflammation-mediated damage in vivo.

METHODS

We observed the effects of TEN on lipopolysaccharide (LPS) induced PD model by behavioral analysis, high-performance liquid chromatography, immunohistochemistry and enzyme-linked immunoadsorbent assay, etc.

RESULTS

We showed that a single intranigral dose of LPSs (10 μg) induced microglial activation, reduced the survival ratio of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the SNpc and reduced dopamine (DA) content in the striatum. Treatment with 300 mg/kg TEN once per day over 14 weeks improved the survival rate of TH-ir neurons in the SNpc to 75%, on the non-injected side. Treatment with 200 or 300 mg/kg TEN once per day over 14 weeks significantly improved DA levels in the striatum to 73% and 81% on the non-injected side, respectively. The excessive production of cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, was abolished by TEN administration.

CONCLUSION

Our results suggest that TEN may play a role in protecting dopaminergic neurons against inflammatory challenge.

Neuroimmunological processes in Parkinson's disease and their relation to α-synuclein: microglia as the referee between neuronal processes and peripheral immunity

The role of neuroinflammation and the adaptive immune system in PD (Parkinson's disease) has been the subject of intense investigation in recent years, both in animal models of parkinsonism and in post-mortem PD brains. However, how these processes relate to and modulate α-syn (α-synuclein) pathology and microglia activation is still poorly understood. Specifically, how the peripheral immune system interacts, regulates and/or is induced by neuroinflammatory processes taking place during PD is still undetermined. We present herein a comprehensive review of the features and impact that neuroinflamation has on neurodegeneration in different animal models of nigral cell death, how this neuroinflammation relates to microglia activation and the way microglia respond to α-syn in vivo. We also discuss a possible role for the peripheral immune system in animal models of parkinsonism, how these findings relate to the state of microglia activation observed in these animal models and how these findings compare with what has been observed in humans with PD. Together, the available data points to the need for development of dual therapeutic strategies that modulate microglia activation to change not only the way microglia interact with the peripheral immune system, but also to modulate the manner in which microglia respond to encounters with α-syn. Lastly, we discuss the immune-modulatory strategies currently under investigation in animal models of parkinsonism and the degree to which one might expect their outcomes to translate faithfully to a clinical setting.

May serum levels of advanced oxidized protein products serve as a prognostic marker of disease duration in patients with idiopathic Parkinson's disease?

Protein and amine halogenation is a type of oxidative stress induced by phagocytic overstimulation, and its role in Parkinson's disease (PD) has not been discerned. We have detected that advanced oxidized protein products, markers of protein halogenation, are reliably enhanced in serum of patients with PD (n=60) relative to control subjects (n=45, p<0.012), and to a lesser extent in the cerebrospinal fluid. Amine halogenation, as evaluated through 3-chlorotyrosine, is not affected. Mieloperoxidase and hydrogen peroxide levels, halogenative factors of phagocytes, are devoid of changes. Levels of advanced oxidized protein products are progressively reduced over time, and the duration of PD is larger in the Hoehn-Yahr-stage-2/3 patients (n=34) with low serum levels (R(2)=0.0145, p<0.003). Levodopa treatment contributes to this reduction (R(2)=0.259, p<0.001). These protein products are not cytotoxic, unlike 3-chlorotyrosine, but they are known to form inflammatory mediators after conjugation with serum albumin. Our observations lead to the hypothesis that the serum level of advanced oxidized protein products is a prognostic marker of PD duration, and these oxidized proteins could participate in the development of parkinsonian neurodegeneration.

Inflammation alters the expression of DMT1, FPN1 and hepcidin, and it causes iron accumulation in central nervous system cells

Inflammation and iron accumulation are present in a variety of neurodegenerative diseases that include Alzheimer's disease and Parkinson's disease. The study of the putative association between inflammation and iron accumulation in central nervous system cells is relevant to understand the contribution of these processes to the progression of neuronal death. In this study, we analyzed the effects of the inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) and of lipopolysaccharide on total cell iron content and on the expression and abundance of the iron transporters divalent metal transporter 1 (DMT1) and Ferroportin 1 (FPN1) in neurons, astrocytes and microglia obtained from rat brain. Considering previous reports indicating that inflammatory stimuli induce the systemic synthesis of the master iron regulator hepcidin, we identified brain cells that produce hepcidin in response to inflammatory stimuli, as well as hepcidin-target cells. We found that inflammatory stimuli increased the expression of DMT1 in neurons, astrocytes, and microglia. Inflammatory stimuli also induced the expression of hepcidin in astrocytes and microglia, but not in neurons. Incubation with hepcidin decreased the expression of FPN1 in the three cell types. The net result of these changes was increased iron accumulation in neurons and microglia but not in astrocytes. The data presented here establish for the first time a causal association between inflammation and iron accumulation in brain cells, probably promoted by changes in DMT1 and FPN1 expression and mediated in part by hepcidin. This connection may potentially contribute to the progression of neurodegenerative diseases by enhancing iron-induced oxidative damage.

Differential contribution of lipoxygenase isozymes to nigrostriatal vulnerability

The 5- and 12/15-lipoxygenase (LOX) isozymes have been implicated to contribute to disease development in CNS disorders such as Alzheimer's disease. These LOX isozymes are distinct in function, with differential effects on neuroinflammation, and the impact of the distinct isozymes in the pathogenesis of Parkinson's disease has not as yet been evaluated. To determine whether the isozymes contribute differently to nigrostriatal vulnerability, the effects of 5- and 12/15-LOX deficiency on dopaminergic tone under naïve and toxicant-challenged conditions were tested. In naïve mice deficient in 5-LOX expression, a modest but significant reduction (18.0% reduction vs. wildtype (WT)) in striatal dopamine (DA) was detected (n=6-8 per genotype). A concomitant decline in striatal tyrosine hydroxylase (TH) enzyme was also revealed in null 5-LOX vs. WT mice (26.2%); however, no changes in levels of DA or TH immunoreactivity were observed in null 12/15-LOX vs. WT mice. When challenged with the selective dopaminergic toxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), WT mice showed a marked reduction in DA (31.9%) and robust astrocytic and microglial activation as compared to saline-treated animals. In contrast, null 5-LOX littermates demonstrated no significant striatal DA depletion or astrogliosis (as noted by Western blot analyses for glial acidic fibrillary protein (GFAP) immunoreactivity). In naïve null 12/15-LOX mice, no significant change in striatal DA values was observed compared to WT, and following MPTP treatment, the transgenics revealed striatal DA reduction similar to the challenged WT mice. Taken together, these data provide the first evidence that: (i) LOX isozymes are involved in the maintenance of normal dopaminergic function in the striatum and (ii) the 5- and 12/15-LOX isozymes contribute differentially to striatal vulnerability in response to neurotoxicant challenge.

Bid signal pathway components are identified in the temporal cortex with Parkinson disease

OBJECTIVE

Parkinson disease (PD), a devastating neurodegenerative disorder, affects motor abilities and cognition as well. It is not clear whether the proapoptotic protein, Bid, is involved in tumor necrosis factor death receptor I (TNFRI)-mediated destructive signal transduction pathways such as cell dysfunction or neurodegeneration in the temporal cortex of patients with PD.

METHODS

Molecular and biochemical approaches were used to dissect mitochondrial related components of the destructive signaling pathway in the temporal cortex from rapidly autopsied brains (postmortem interval mean 2.6 hours). Brains from patients with PD (n = 15) had an average age of 81.4 years, compared to the average age of 84.36 years in age-matched control patient brains (n = 15).

RESULTS

TNFRI and its adaptor protein, TRADD, were not only present in the cytoplasm of the temporal cortex, but were significantly elevated (42.3% and 136.1%, respectively) in PD brains compared to age-matched control brains. Bid in the PD temporal cortex could be further cleaved into tBid in the cytosol, which is translocated into the mitochondria, where cytochrome c is then released and caspase-3 is subsequently activated.

CONCLUSION

Patients with PD have an activated Bid-mediated destructive signal pathway via TNFRI in the temporal cortex. Such deficits are pervasive, suggesting that they might contribute to cortex degeneration as PD manifests.

Ceramide sphingolipid signaling mediates Tumor Necrosis Factor (TNF)-dependent toxicity via caspase signaling in dopaminergic neurons

BACKGROUND

Dopaminergic (DA) neurons in the ventral midbrain selectively degenerate in Parkinson's disease (PD) in part because their oxidative environment in the substantia nigra (SN) may render them vulnerable to neuroinflammatory stimuli. Chronic inhibition of soluble Tumor Necrosis Factor (TNF) with dominant-negative TNF inhibitors protects DA neurons in rat models of parkinsonism, yet the molecular mechanisms and pathway(s) that mediate TNF toxicity remain(s) to be clearly identified. Here we investigated the contribution of ceramide sphingolipid signaling in TNF-dependent toxicity.

RESULTS

Ceramide dose-dependently reduced the viability of DA neuroblastoma cells and primary DA neurons and pharmacological inhibition of sphingomyelinases (SMases) with three different inhibitors during TNF treatment afforded significant neuroprotection by attenuating increased endoplasmic reticulum (ER) stress, loss of mitochondrial membrane potential, caspase-3 activation and decreases in Akt phosphorylation. Using lipidomics mass spectrometry we confirmed that TNF treatment not only promotes generation of ceramide, but also leads to accumulation of several atypical deoxy-sphingoid bases (DSBs). Exposure of DA neuroblastoma cells to atypical DSBs in the micromolar range reduced cell viability and inhibited neurite outgrowth and branching in primary DA neurons, suggesting that TNF-induced de novo synthesis of atypical DSBs may be a secondary mechanism involved in mediating its neurotoxicity in DA neurons.

CONCLUSIONS

We conclude that TNF/TNFR1-dependent activation of SMases generates ceramide and sphingolipid species that promote degeneration and caspase-dependent cell death of DA neurons. Ceramide and atypical DSBs may represent novel drug targets for development of neuroprotective strategies that can delay or attenuate the progressive loss of nigral DA neurons in patients with PD.

Biology of Parkinson's disease: pathogenesis and pathophysiology of a multisystem neurodegenerative disorder

Parkinson's disease (PD) is the second most common movement disorder. The characteristic motor impairments - bradykinesia, rigidity, and resting tremor - result from degenerative loss of midbrain dopamine (DA) neurons in the substantia nigra, and are responsive to symptomatic treatment with dopaminergic medications and functional neurosurgery. PD is also the second most common neurodegenerative disorder. Viewed from this perspective, PD is a disorder of multiple functional systems, not simply the motor system, and of multiple neurotransmitter systems, not merely that of DA. The characteristic pathology - intraneuronal Lewy body inclusions and reduced numbers of surviving neurons - is similar in each of the targeted neuron groups, suggesting a common neurodegenerative process. Pathological and experimental studies indicate that oxidative stress, proteolytic stress, and inflammation figure prominently in the pathogenesis of PD. Yet, whether any of these mechanisms plays a causal role in human PD is unknown, because to date we have no proven neuroprotective therapies that slow or reverse disease progression in patients with PD. We are beginning to understand the pathophysiology of motor dysfunction in PD, but its etiopathogenesis as a neurodegenerative disorder remains poorly understood.

Postmortem studies in Parkinson's disease

No animal model to date perfectly replicates Parkinson's disease (PD) etiopathogenesis, and the anatomical organization of the nigrostriatal system differs considerably between species. Human postmortem material therefore remains the gold standard for both formulating hypotheses for subsequent testing in in vitro and in vivo PD models and verifying hypotheses derived from experimental PD models with regard to their validity in the human disease. This article focuses on recent and relevant fields in which human postmortem work has generated significant impact in our understanding of PD. These fields include Lewy body formation, regional vulnerability of dopaminergic neurons, oxidative/nitrative cellular stress, inflammation, apoptosis, infectious and environmental agents, and nondopaminergic lesions.

The IkappaB kinase family phosphorylates the Parkinson's disease kinase LRRK2 at Ser935 and Ser910 during Toll-like receptor signaling

Mutations in leucine-rich repeat kinase 2 (LRRK2) are strongly associated with late-onset autosomal dominant Parkinson's disease. LRRK2 is highly expressed in immune cells and recent work points towards a link between LRRK2 and innate immunity. Here we demonstrate that stimulation of the Toll-Like Receptor (TLR) pathway by MyD88-dependent agonists in bone marrow-derived macrophages (BMDMs) or RAW264.7 macrophages induces marked phosphorylation of LRRK2 at Ser910 and Ser935, the phosphorylation sites that regulate the binding of 14-3-3 to LRRK2. Phosphorylation of these residues is prevented by knock-out of MyD88 in BMDMs, but not the alternative TLR adaptor protein TRIF. Utilising both pharmacological inhibitors, including a new TAK1 inhibitor, NG25, and genetic models, we provide evidence that both the canonical (IKKα and IKKβ) and IKK-related (IKKε and TBK1) kinases mediate TLR agonist induced phosphorylation of LRRK2 in vivo. Moreover, all four IKK members directly phosphorylate LRRK2 at Ser910 and Ser935 in vitro. Consistent with previous work describing Ser910 and Ser935 as pharmacodynamic biomarkers of LRRK2 activity, we find that the TLR independent basal phosphorylation of LRRK2 at Ser910 and Ser935 is abolished following treatment of macrophages with LRRK2 kinase inhibitors. However, the increased phosphorylation of Ser910 and Ser935 induced by activation of the MyD88 pathway is insensitive to LRRK2 kinase inhibitors. Finally, employing LRRK2-deficient BMDMs, we present data indicating that LRRK2 does not play a major role in regulating the secretion of inflammatory cytokines induced by activation of the MyD88 pathway. Our findings provide the first direct link between LRRK2 and the IKKs that mediate many immune responses. Further work is required to uncover the physiological roles that phosphorylation of LRRK2 by IKKs play in controlling macrophage biology and to determine how phosphorylation of LRRK2 by IKKs impacts upon the use of Ser910 and Ser935 as pharmacodynamic biomarkers.

Plasma oxidative and inflammatory markers in patients with idiopathic Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative disorder after alzheimer's disease. Neuroinflammation and oxidative damage are implicated to be responsible for the pathogenesis of neurodegenerative diseases. However, there are a few studies showing the changes in the biomarkers for neuroinflammation and oxidative damage in neurodegenerative diseases. In our study we aimed to examine the role of the molecules that are involved in oxidative stress and inflammation in PD patients taking L: -dopa treatment. Oxidized-LDL (ox-LDL), high-sensitivity C-reactive protein (hs-CRP) and the soluble intracellular adhesion molecule (ICAM) were chosen as biomarkers for systemic inflammation and oxidative damage. The patients were classified according to the Hoehn-Yahr staging system. Forty-five idiopathic L: -dopa-given PD patients and 25 age-matched healthy controls were examined. Plasma ox-LDL and ICAM levels were significantly higher in PD patients when compared with controls (p < 0.001 and p < 0.05, respectively). PD patients at all stages had significantly higher plasma ox-LDL levels than controls (p < 0.001). Plasma ICAM levels at stage 1 and 2 and CRP levels at stage 2 patients were significantly higher than controls (p < 0.05, p < 0.05, and p < 0.01, respectively). We insist that further studies have to be conducted to establish neuroinflammation and oxidative damage in PD. Establishing the roles of these pathological processes in PD might be the key to effective therapy at an early stage by antioxidants and/or anti-inflammatory drugs.

Neuroinflammation and synaptic loss

Neuroinflammation plays a critical role in the progression of many neurodegenerative, neuropsychiatric and viral diseases. In neuroinflammation, activated microglia and astrocytes release cytokines and chemokines as well as nitric oxide, which in turn activate many signal transduction pathways. The cytokines, interleukin-1 beta and tumor necrosis factor alpha, regulate transcription of a number of genes within the brain, which can lead to the formation of pro-inflammatory products of the arachidonic acid cascade. Formation of pro-inflammatory agents and associated cytotoxic products during neuroinflammation can be detrimental to neurons by altering synaptic proteins. Neuroinflammation as well as excitotoxic insults reduce synaptic markers such as synaptophysin and drebrin. Neurodegenerative, neuropsychiatric illnesses and viral infections are accompanied by loss of both pre- and post-synaptic proteins. These synaptic changes may contribute to the progressive cognitive decline and behavioral changes associated with these illnesses.

Transduced Tat-DJ-1 protein protects against oxidative stress-induced SH-SY5Y cell death and Parkinson disease in a mouse model

Parkinson's disease (PD) is a well known neurodegenerative disorder characterized by selective loss of dopaminergic neurons in the substantia nigra pars compact (SN). Although the exact mechanism remains unclear, oxidative stress plays a critical role in the pathogenesis of PD. DJ-1 is a multifunctional protein, a potent antioxidant and chaperone, the loss of function of which is linked to the autosomal recessive early onset of PD. Therefore, we investigated the protective effects of DJ-1 protein against SH-SY5Y cells and in a PD mouse model using a cell permeable Tat-DJ-1 protein. Tat-DJ-1 protein rapidly transduced into the cells and showed a protective effect on 6-hydroxydopamine (6-OHDA)-induced neuronal cell death by reducing the reactive oxygen species (ROS). In addition, we found that Tat-DJ-1 protein protects against dopaminergic neuronal cell death in 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP)-induced PD mouse models. These results suggest that Tat-DJ-1 protein provides a potential therapeutic strategy for against ROS related human diseases including PD.

Kinin-mediated inflammation in neurodegenerative disorders

The mediatory role of kinins in both acute and chronic inflammation within nervous tissues has been widely described. Bradykinin, the major representative of these bioactive peptides, is one of a few mediators of inflammation that directly stimulates afferent nerves due to the broad expression of specific kinin receptors in cell types in these tissues. Moreover, kinins may be delivered to a site of injury not only after their production at the endothelium surface but also following their local production through the enzymatic degradation of kininogens at the surface of nerve cells. A strong correlation between inflammatory processes and neurodegeneration has been established. The activation of nerve cells, particularly microglia, in response to injury, trauma or infection initiates a number of reactions in the neuronal neighborhood that can lead to cell death after the prolonged action of inflammatory substances. In recent years, there has been a growing interest in the effects of kinins on neuronal destruction. In these studies, the overexpression of proteins involved in kinin generation or of kinin receptors has been observed in several neurologic disorders including neurodegenerative diseases such Alzheimer's disease and multiple sclerosis as well as disorders associated with a deficiency in cell communication such as epilepsy. This review is focused on recent findings that provide reliable evidence of the mediatory role of kinins in the inflammatory responses associated with different neurological disorders. A deeper understanding of the role of kinins in neurodegenerative diseases is likely to promote the future development of new therapeutic strategies for the control of these disorders. An example of this could be the prospective use of kinin receptor antagonists.

Neuronal RING finger protein 11 (RNF11) regulates canonical NF-κB signaling

Background

The RING domain-containing protein RING finger protein 11 (RNF11) is a member of the A20 ubiquitin-editing protein complex and modulates peripheral NF-κB signaling. RNF11 is robustly expressed in neurons and colocalizes with a population of α-synuclein-positive Lewy bodies and neurites in Parkinson disease patients. The NF-κB pathway has an important role in the vertebrate nervous system, where the absence of NF-κB activity during development can result in learning and memory deficits, whereas chronic NF-κB activation is associated with persistent neuroinflammation. We examined the functional role of RNF11 with respect to canonical NF-κB signaling in neurons to gain understanding of the tight association of inflammatory pathways, including NF-κB, with the pathogenesis of neurodegenerative diseases.

Methods and results

Luciferase assays were employed to assess NF-κB activity under targeted short hairpin RNA (shRNA) knockdown of RNF11 in human neuroblastoma cells and murine primary neurons, which suggested that RNF11 acts as a negative regulator of canonical neuronal NF-κB signaling. These results were further supported by analyses of p65 translocation to the nucleus following depletion of RNF11. Coimmunoprecipitation experiments indicated that RNF11 associates with members of the A20 ubiquitin-editing protein complex in neurons. Site-directed mutagenesis of the myristoylation domain, which is necessary for endosomal targeting of RNF11, altered the impact of RNF11 on NF-κB signaling and abrogated RNF11’s association with the A20 ubiquitin-editing protein complex. A partial effect on canonical NF-κB signaling and an association with the A20 ubiquitin-editing protein complex was observed with mutagenesis of the PPxY motif, a proline-rich region involved in Nedd4-like protein interactions. Last, shRNA-mediated reduction of RNF11 in neurons and neuronal cell lines elevated levels of monocyte chemoattractant protein 1 and TNF-α mRNA and proteins, suggesting that NF-κB signaling and associated inflammatory responses are aberrantly regulated in the absence of RNF11.

Conclusions

Our findings support the hypothesis that, in the nervous system, RNF11 negatively regulates canonical NF-κB signaling. Reduced or functionally compromised RNF11 could influence NF-κB-associated neuronal functions, including exaggerated inflammatory responses that may have implications for neurodegenerative disease pathogenesis and progression.

Understanding Alcoholism Through microRNA Signatures in Brains of Human Alcoholics

Advances in the fields of genomics and genetics in the last decade have identified a large number of genes that can potentially influence alcohol-drinking behavior in humans as well as animal models. Consequently, the task of identifying efficient molecular targets that could be used to develop effective therapeutics against the disease has become increasingly daunting. One of the reasons for this is the fact that each of the many alcohol-responsive genes only contributes a small effect to the overall mechanism and disease phenotype, as is characteristic of complex traits. Current research trends are hence shifting toward the analysis of gene networks rather than emphasizing individual genes. The discovery of microRNAs and their mechanisms of action on regulation of transcript level and protein translation have made evident the utility of these small non-coding RNA molecules that act as central coordinators of multiple cross-communicating cellular pathways. Cells exploit the fact that a single microRNA can target hundreds of mRNA transcripts and that a single mRNA transcript can be simultaneously targeted by distinct microRNAs, to ensure fine-tuned and/or redundant control over a large number of cellular functions. By the same token, we can use these properties of microRNAs to develop novel, targeted strategies to combat complex disorders. In this review, we will focus on recent discoveries of microRNA signatures in brain of human alcoholics supporting the hypothesis that changes in gene expression and regulation by microRNAs are responsible for long-term neuroadaptations occurring during development of alcoholism. We also discuss insights into the potential modulation of epigenetic regulators by a subset of microRNAs. Taken together, microRNA activity may be controlling many of the cellular mechanisms already known to be involved in the development of alcoholism, and suggests potential targets for the development of novel therapeutic interventions.

Peripheral inflammation increases the deleterious effect of CNS inflammation on the nigrostriatal dopaminergic system

Evidence supports the role of inflammation in the development of neurodegenerative diseases. In this work, we are interested in inflammation as a risk factor by itself and not only as a factor contributing to neurodegeneration. We tested the influence of a mild to moderate peripheral inflammation (injection of carrageenan into the paws of rats) on the degeneration of dopaminergic neurons in an animal model based on the intranigral injection of lipopolysaccharide (LPS), a potent inflammatory agent. Overall, the treatment with carrageenan increased the effect of the intranigral injection of LPS on the loss of dopaminergic neurons in the SN along with all the other parameters studied, including: serum levels of the inflammatory markers TNF-α, IL-1β, IL-6 and C-reactive protein; activation of microglia, expression of proinflammatory cytokines, the adhesion molecule ICAM and the enzyme iNOS, loss of astrocytes and damage to the blood brain barrier (BBB). The possible implication of BBB rupture in the increased loss of dopaminergic neurons has been studied using another Parkinson's disease animal model based on the intraperitoneal injection of rotenone. In this experiment, loss of dopaminergic neurons was also strengthened by carrageenan, without affecting the BBB. In conclusion, our data show that a mild to moderate peripheral inflammation can exacerbate the degeneration of dopaminergic neurons caused by a harmful stimulus.

Apoptosis signal-regulating kinase 1 mediates MPTP toxicity and regulates glial activation

Apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein kinase 3 family, is activated by oxidative stress. The death-signaling pathway mediated by ASK1 is inhibited by DJ-1, which is linked to recessively inherited Parkinson's disease (PD). Considering that DJ-1 deficiency exacerbates the toxicity of the mitochondrial complex I inhibitor 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we sought to investigate the direct role and mechanism of ASK1 in MPTP-induced dopamine neuron toxicity. In the present study, we found that MPTP administration to wild-type mice activates ASK1 in the midbrain. In ASK1 null mice, MPTP-induced motor impairment was less profound, and striatal dopamine content and nigral dopamine neuron counts were relatively preserved compared to wild-type littermates. Further, microglia and astrocyte activation seen in wild-type mice challenged with MPTP was markedly attenuated in ASK⁻/⁻ mice. These data suggest that ASK1 is a key player in MPTP-induced glial activation linking oxidative stress with neuroinflammation, two well recognized pathogenetic factors in PD. These findings demonstrate that ASK1 is an important effector of MPTP-induced toxicity and suggest that inhibiting this kinase is a plausible therapeutic strategy for protecting dopamine neurons in PD.

Gender differences in the IL6 -174G>C and ESR2 1730G>A polymorphisms and the risk of Parkinson's disease

The -174G>C (rs1800795) single nucleotide polymorphism (SNP) in the promoter of the interleukin-6 (IL6) gene and the 1730G>A (rs4986938) SNP in the estrogen receptor beta (ESR2) may influence the risk of Parkinson's disease (PD). We investigated these SNPs in 380 unrelated US Caucasian PD cases and 522 controls, including 452 individuals of Ashkenazi Jewish (AJ) origin (260 PD, 192 controls). The G allele of the -174G>C SNP was more common in AJ PD cases (p=0.033) as well as in Non-Jewish (NJ) men with PD (p=0.022). The GG genotype increased the risk of PD by over two fold in NJ men (OR=2.11, 95%CI: 1.14-3.89, p=0.017), and approached significance in the total AJ group with PD (OR=1.42, 95%CI: 0.97-2.06, p=0.067). The A allele of the ESR2 1730G>A SNP was associated with a decreased risk for PD in AJ women, and in this group, having the AA genotype decreased the risk of PD by half (OR=0.45, 95%CI: 0.22-0.92, p=0.029). Our data supports a role for the IL6 -174G>C G allele in AJ individuals overall. In NJ Caucasians, this role appears to be gender mediated. In both groups, the effect is independent from ESR2 1730G>A. A separate association for the ESR2 1730G>A SNP was found exclusively in women of AJ descent. Other polymorphisms in tight linkage disequilibrium with the SNP differentially influencing expression, ethnic differences in allele distribution, and gender differences in genetic load related to PD, may underlie our findings. Larger studies in diverse populations, including analysis of surrounding regions are recommended.

Cocoa and chocolate in human health and disease

Cocoa contains more phenolic antioxidants than most foods. Flavonoids, including catechin, epicatechin, and procyanidins predominate in antioxidant activity. The tricyclic structure of the flavonoids determines antioxidant effects that scavenge reactive oxygen species, chelate Fe2+ and Cu+, inhibit enzymes, and upregulate antioxidant defenses. The epicatechin content of cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated through anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-κB. Antioxidant effects of cocoa may directly influence insulin resistance and, in turn, reduce risk for diabetes. Further, cocoa consumption may stimulate changes in redox-sensitive signaling pathways involved in gene expression and the immune response. Cocoa can protect nerves from injury and inflammation, protect the skin from oxidative damage from UV radiation in topical preparations, and have beneficial effects on satiety, cognitive function, and mood. As cocoa is predominantly consumed as energy-dense chocolate, potential detrimental effects of overconsumption exist, including increased risk of weight gain. Overall, research to date suggests that the benefits of moderate cocoa or dark chocolate consumption likely outweigh the risks.

Etiology and pathogenesis of Parkinson's disease

The past 25 years have seen a major expansion of knowledge concerning the cause of Parkinson's disease provided by an understanding of environmental and genetic factors that underlie the loss of nigral dopaminergic neurons. Based on the actions of toxins, postmortem investigations, and gene defects responsible for familial Parkinson's disease, there is now a general consensus about the mechanisms of cell death that contribute to neuronal loss in Parkinson's disease. Mitochondrial dysfunction, oxidative stress, altered protein handling, and inflammatory change are considered to lead to cell dysfunction and death by apoptosis or autophagy. Ageing is the single most important risk factor for Parkinson's disease, and the biochemical changes that are a consequence of aging amplify these abnormalities in Parkinson's disease brain. What remains to be determined is the combination and sequence of events leading to cell death and whether this is identical in all brain regions where pathology occurs and in all individuals with Parkinson's disease. Focusing on those events that characterize Parkinson's disease, namely, mitochondrial dysfunction and Lewy body formation, may be the key to further advancing the understanding of pathogenesis and to taking these mechanisms forward as a means of defining targets for neuroprotection.

Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain

The brain is one of the major target organs of alcohol actions. Alcohol abuse can lead to alterations in brain structure and functions and, in some cases, to neurodegeneration. Cognitive deficits and alcohol dependence are highly damaging consequences of alcohol abuse. Clinical and experimental studies have demonstrated that the developing brain is particularly vulnerable to alcohol, and that drinking during gestation can lead to a range of physical, learning and behavioral defects (fetal alcohol spectrum disorders), with the most dramatic presentation corresponding to fetal alcohol syndrome. Recent findings also indicate that adolescence is a stage of brain maturation and that heavy drinking at this stage can have a negative impact on brain structure and functions causing important short- and long-term cognitive and behavioral consequences. The effects of alcohol on the brain are not uniform; some brain areas or cell populations are more vulnerable than others. The prefrontal cortex, the hippocampus, the cerebellum, the white matter and glial cells are particularly susceptible to the effects of ethanol. The molecular actions of alcohol on the brain are complex and involve numerous mechanisms and signaling pathways. Some of the mechanisms involved are common for the adult brain and for the developing brain, while others depend on the developmental stage. During brain ontogeny, alcohol causes irreversible alterations to the brain structure. It also impairs several molecular, neurochemical and cellular events taking place during normal brain development, including alterations in both gene expression regulation and the molecules involved in cell-cell interactions, interference with the mitogenic and growth factor response, enhancement of free radical formation and derangements of glial cell functions. However, in both adult and adolescent brains, alcohol damages specific brain areas through mechanisms involving excitotoxicity, free radical formation and neuroinflammatory damage resulting from activation of the innate immune system mediated by TLR4 receptors. Alcohol also acts on specific membrane proteins, such as neurotransmitter receptors (e.g. NMDA, GABA-A), ion channels (e.g. L-type Ca²⁺ channels, GIRKs), and signaling pathways (e.g. PKA and PKC signaling). These effects might underlie the wide variety of behavioral effects induced by ethanol drinking. The neuroadaptive changes affecting neurotransmission systems which are more sensitive to the acute effects of alcohol occur after long-term alcohol consumption. Alcohol-induced maladaptations in the dopaminergic mesolimbic system, abnormal plastic changes in the reward-related brain areas and genetic and epigenetic factors may all contribute to alcohol reinforcement and alcohol addiction. This manuscript reviews the mechanisms by which ethanol impacts the adult and the developing brain, and causes both neural impairments and cognitive and behavioral dysfunctions. The identification and the understanding of the cellular and molecular mechanisms involved in ethanol toxicity might contribute to the development of treatments and/or therapeutic agents that could reduce or eliminate the deleterious effects of alcohol on the brain.

Kinin generation from exogenous kininogens at the surface of retinoic acid-differentiated human neuroblastoma IMR-32 cells after stimulation with interferon-γ

Bradykinin-related peptides, kinins, ubiquitously occur in the nervous system and together with other pro-inflammatory mediators contribute to pathological states of that tissue such as edema and chronic pain. In the current work we characterized the kinin-forming system of neuronal cells obtained by differentiation of human neuroblastoma cell line IMR-32 with retinoic acid. These cells were shown to concentrate exogenous kinin precursors, kininogens, on the surface, release kinins from kininogens and subsequently convert kinins to their des-Arg metabolites. Significantly higher amounts of kinins and des-Arg-kinins were produced after cell stimulation with interferon-γ, a potent pro-inflammatory mediator involved in many neurological disorders. The expression of the major tissue kininogenase (the human kallikrein 1) and the major cell membrane-bound kininase (the carboxypeptidase M) also increased after cell stimulation with interferon-γ, suggesting the involvement of these enzymes in the kinin production and degradation, respectively. Interferon-γ was also able to up-regulate the expression of two known subtypes of kinin receptors. On the protein level, the changes were only observed in the expression of the des-Arg-kinin-specific type 1 receptor which functions in the propagation of the inflammatory state. Taken together, these results suggest a novel way for local kinin and des-Arg-kinin generation in the nervous tissue during pathological states accompanied by interferon-γ release.

Tumor necrosis factor-alpha (TNF-α) levels in aqueous humor of primary open angle glaucoma

Purpose:

Tumor necrosis factor alpha (TNF-α), a macrophage/monocyte derived pluripotent cytokine is associated with tissue ischemia, neuronal damage and remodeling. The physiological level of TNF-α in aqueous humor of normal and glaucomatous eyes is unknown. In this study, we evaluated the TNF-α levels in aqueous in patients with primary open angle glaucoma (POAG) and compared them to controls.

Methods:

50–100 μL of undiluted aqueous humor samples were obtained from eyes of 32 POAG patients who underwent cataract extraction, trabeculectomy or aqueous shunt implantation. Controls were obtained from 32 normal subjects who underwent routine cataract surgery. TNF-α levels were quantified using singleplex bead immunoassay analysis.

Results:

The average TNF-α level in POAG samples was 2.72 ± 1.5 pg/mL (mean ± SD). The average TNF-α level in normal samples was 1.59 ± 0.46 pg/mL (mean ± SD). Significant increase of TNF-α levels in POAG samples was noted in comparison to normal samples (P < 0.001).

Conclusion:

TNF-α levels are elevated in aqueous in patients with POAG compared to normal subjects based on highly sensitive Luminex^® bead immunoassay and may be a reliable biomarker in the progression of glaucoma.

Inflammatory Animal Model for Parkinson's Disease: The Intranigral Injection of LPS Induced the Inflammatory Process along with the Selective Degeneration of Nigrostriatal Dopaminergic Neurons

We have developed an animal model of degeneration of the nigrostriatal dopaminergic neurons, the neuronal system involved in Parkinson's disease (PD). The implication of neuroinflammation on this disease was originally established in 1988, when the presence of activated microglia in the substantia nigra (SN) of parkinsonians was reported by McGeer et al. Neuroinflammation could be involved in the progression of the disease or even has more direct implications. We injected 2 μg of the potent proinflammatory compound lipopolysaccharide (LPS) in different areas of the CNS, finding that SN displayed the highest inflammatory response and that dopaminergic (body) neurons showed a special and specific sensitivity to this process with the induction of selective dopaminergic degeneration. Neurodegeneration is induced by inflammation since it is prevented by anti-inflammatory compounds. The special sensitivity of dopaminergic neurons seems to be related to the endogenous dopaminergic content, since it is overcome by dopamine depletion. Compounds that activate microglia or induce inflammation have similar effects to LPS. This model suggest that inflammation is an important component of the degeneration of the nigrostriatal dopaminergic system, probably also in PD. Anti-inflammatory treatments could be useful to prevent or slow down the rate of dopaminergic degeneration in this disease.

The origins of oxidant stress in Parkinson's disease and therapeutic strategies

Parkinson's disease (PD) is a major world-wide health problem afflicting millions of the aged population. Factors that act on most or all cell types (pan-cellular factors), particularly genetic mutations and environmental toxins, have dominated public discussions of disease etiology. Although there is compelling evidence supporting an association between disease risk and these factors, the pattern of neuronal pathology and cell loss is difficult to explain without cell-specific factors. This article focuses on recent studies showing that the neurons at greatest risk in PD-substantia nigra pars compacta dopamine neurons-have a distinctive physiological phenotype that could contribute to their vulnerability. The opening of L-type calcium channels during autonomous pacemaking results in sustained calcium entry into the cytoplasm of substantia nigra pars compacta dopamine neurons, resulting in elevated mitochondrial oxidant stress and susceptibility to toxins used to create animal models of PD. This cell-specific stress could increase the negative consequences of pan-cellular factors that broadly challenge either mitochondrial or proteostatic competence. The availability of well-tolerated, orally deliverable antagonists for L-type calcium channels points to a novel neuroprotective strategy that could complement current attempts to boost mitochondrial function in the early stages of the disease.

Ghrelin receptor signaling: a promising therapeutic target for metabolic syndrome and cognitive dysfunction

The neuroendocrine hormone ghrelin is an octanoylated 28-residue peptide that exerts numerous physiological functions. Ghrelin exerts its effects on the body mainly through a highly conserved G protein-coupled receptor known as the growth hormone secretagagogue receptor subtype 1a (GHS-R1a). Ghrelin and GSH-R1a are widely expressed in both peripheral and central tissues/organs, and ghrelin signaling plays a critical role in maintaining energy balance and neuronal health. The multiple orexigenic effects of ghrelin and its receptor have been studied in great detail, and GHS-R1a-mediated ghrelin signaling has long been a promising target for the treatment of metabolic disorders, such as obesity. In addition to its well-characterized metabolic effects, there is also mounting evidence that ghrelin-mediated GHS-R1a signaling exerts neuroprotective effects on the brain. In this review, we will summarize some of the effects of ghrelin-mediated GSH-R1a signaling on peripheral energy balance and cognitive function. We will also discuss the potential pharmacotherapeutic role of GSH-R1a-mediated ghrelin signaling for the treatment of complex neuroendocrine disorders.

Reduced DNA oxidation in aged prostaglandin H synthase-1 knockout mice

Prostaglandin H synthase (PHS)-2 (COX-2) is implicated in the neurodegeneration of Alzheimer and Parkinson diseases. Multiple mechanisms may be involved, including PHS-catalyzed bioactivation of neurotransmitters, precursors, and metabolites to neurotoxic free radical intermediates. Herein, in vitro studies with the purified PHS-1 (COX-1) isoform and in vivo studies of aging PHS-1 knockout mice were used to evaluate the potential neurodegenerative role of PHS-1-catalyzed bioactivation of endogenous neurotransmitters to free radical intermediates that enhance reactive oxygen species formation and oxidative DNA damage. The brains of 2-year-old wild-type (+/+) PHS-1 normal and heterozygous (+/-) and homozygous (-/-) PHS-1 knockout mice were analyzed for 8-oxo-2'-deoxyguanosine formation, characterized by high-performance liquid chromatography with electrochemical detection and by immunohistochemistry. Compared to aging PHS-1(+/+) normal mice, aging PHS-1(-/-) knockout mice had less oxidative DNA damage in the cortex, hippocampus, cerebellum, and brain stem. This PHS-1-dependent oxidative damage was not observed in young mice. In vitro incubation of purified PHS-1 and 2'-deoxyguanosine with dopamine, L-DOPA, and epinephrine, but not glutamate or norepinephrine, enhanced oxidative DNA damage. These results suggest that PHS-1-dependent accumulation of oxidatively damaged macromolecules including DNA may contribute to the mechanisms and risk factors of aging-related neurodegeneration.

Use of non-steroidal anti-inflammatory drugs and risk of Parkinson's disease: nested case-control study

OBJECTIVE

To evaluate the relation between Parkinson's disease and prior use of non-steroidal anti-inflammatory drugs (NSAIDs) in a large cohort of men.

DESIGN

Case-control analysis nested in the Physicians' Health Study.

PARTICIPANTS

22,007 male physicians aged 40-84 years without indications for or contraindications to regular NSAID use and free of Parkinson's disease at baseline. Cases and controls were matched by age alone or by age and scores for confounders (comorbidity and indicators of NSAID use). Up to five controls were matched to each of 616 cases by age and 565 cases by age and confounder scores.

SETTING

United States.

MAIN OUTCOME MEASURES

Odds of having been exposed to prior non-aspirin NSAID or aspirin use by participants with Parkinson's disease and by their controls in each case-control set.

RESULTS

Participants who had ever used non-aspirin NSAIDs had an increased risk of Parkinson's disease (odds ratio 1.28 (95% CI 1.05 to 1.56) in the age matched group but not in the group also matched on confounder scores (odds ratio 1.17 (0.94 to 1.46)). There was an increased risk of Parkinson's disease in men who had 1-2 years of regular non-aspirin NSAID use (odds ratio 1.35 (1.07 to 1.70)), a finding that remained significant after matching for confounder scores as well (odds ratio 1.35 (1.05 to 1.75)). In contrast, the significant association of use of non-aspirin NSAIDs for ≥ 5 years (odds ratio 1.48 (1.05 to 2.09)) in the age matched group was entirely attenuated in the group also matched on confounder scores (1.03 (0.70 to 1.53)). There was also a suggestion that men who regularly used aspirin had an increased risk of Parkinson's disease. Positive associations between non-aspirin NSAID or aspirin and risk of Parkinson's disease tended to disappear when analyses were limited to drug use ≥ 5 years before the disease diagnosis.

CONCLUSIONS

This case-control study did not find evidence that NSAID use reduces Parkinson's disease risk. The positive associations observed between NSAID use and Parkinson's disease might have been due to confounding by indication as the use was clustered in the few years before disease diagnosis.

Interleukin-18 promoter polymorphisms and risk of Parkinson's disease in a Han Chinese population

The etiology of sporadic Parkinson's disease (PD) is not well established. Interleukin-18 (IL-18), a member of pro-inflammatory cytokines, might influence the risk of sporadic PD occurrence and development. In this study, two DNA polymorphisms at interleukin (IL)-18 promoter, -607C/A (rs1946518) and -137G/C (rs187238), were examined in sporadic PD patients in a Han Chinese population with 290 sporadic PD patients and 200 healthy controls. Direct sequencing was performed in 10% of the samples to validate the genotyping results. The results revealed that for -607C/A polymorphisms, there were significant differences in genotype distribution between PD and control in the total sample (P=0.017) and between LOPD and healthy-matched controls subgroup (P=0.011). For -137G/C polymorphisms, there were no significant differences in genotype distribution and gender and age-related differences between PD and control in the total sample (P=0.610). Results in this study revealed that the IL-18 607C/A polymorphism is a risk factor for sporadic LOPD in Han Chinese population, while IL-18 137G/C polymorphism is not a risk factor for sporadic PD in the Han Chinese population.

Preweaning Mn exposure leads to prolonged astrocyte activation and lasting effects on the dopaminergic system in adult male rats

Little is known about the effects of manganese (Mn) exposure over neurodevelopment and whether these early insults result in effects lasting into adulthood. To determine if early Mn exposure produces lasting neurobehavioral and neurochemical effects, we treated neonate rats with oral Mn (0, 25, or 50 mg Mn/kg/d over PND 1-21) and evaluated (1) behavioral performance in the open arena in the absence (PND 97) and presence (PND 98) of a d-amphetamine challenge, (2) brain dopamine D1 and D2-like receptors and dopamine transporter densities in the prefrontal cortex, striatum, and nucleus accumbens (PND 107), and (3) astrocyte marker glial fibrillary acidic protein (GFAP) levels in these same brain regions (PND 24 and 107). We found that preweaning Mn exposure did not alter locomotor activity or behavior disinhibition in adult rats, though Mn-exposed animals did exhibit an enhanced locomotor response to d-amphetamine challenge. Preweaning Mn exposure led to increased D1 and D2 receptor levels in the nucleus accumbens and prefrontal cortex, respectively, compared with controls. We also found increased GFAP expression in the prefrontal cortex in Mn-exposed PND 24 weanlings, and increased GFAP levels in prefrontal cortex, medial striatum and nucleus accumbens of adult (PND 107) rats exposed to preweaning Mn, indicating an effect of Mn exposure on astrogliosis that persisted and/or progressed to other brain regions in adult animals. These data show that preweaning Mn exposure leads to lasting molecular and functional impacts in multiple brain regions of adult animals, long after brain Mn levels returned to normal.

Clinical efficacy of istradefylline (KW-6002) in Parkinson's disease: a randomized, controlled study

The objectives of this study were to evaluate the efficacy of istradefylline at an oral dose of 20 mg or 40 mg once daily for 12 weeks in Parkinson's disease (PD) patients with motor complications on levodopa therapy based on the change in the daily OFF time compared with placebo and to assess the safety at these doses. A total of 363 subjects were randomly assigned to receive 20 mg/day istradefylline (n = 119), 40 mg/day istradefylline (n = 125), or placebo (n = 119). The primary outcome variable was the change from baseline at endpoint in daily OFF time based on patients' ON/OFF diaries. At endpoint, the daily OFF time reduced from baseline by 1.31 hours for 20 mg/day istradefylline (P = 0.013 as compared to the placebo), 1.58 hours for 40 mg/day istradefylline (P < 0.001), and 0.66 hours for placebo; istradefylline significantly reduced the daily OFF time compared with placebo. The UPDRS Part III subscale score (ON state) reduced by 5.7 at endpoint in both istradefylline groups and 3.7 in the placebo group (P = 0.006 for 20 mg/day and P = 0.006 for 40 mg/day group as compared with placebo). The most commonly reported drug-related treatment emergent adverse event (TEAE) was dyskinesia, which occurred in 2.5% (3/119) of subjects receiving placebo, 8.5% (10/118) receiving 20 mg/day istradefylline, and 6.4% (8/125) receiving 40 mg/day istradefylline. We conclude that istradefylline at 20 mg and 40 mg once daily is effective in relieving wearing-off fluctuations of PD patients. In addition, istradefylline was well tolerated at both doses.

Rosmarinic acid antagonized 1-methyl-4-phenylpyridinium (MPP+)-induced neurotoxicity in MES23.5 dopaminergic cells

Rosmarinic acid (RA) is a naturally occurring polyphenolic compound found in various plant families. We previously reported that RA exerted protective effects against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity through antioxidative properties. In this study, we investigated whether RA could prevent effects of 1-methyl-4-phenylpyridinium (MPP(+))-induced insult in MES23.5 dopamineric cells. 1-Methyl-4-phenylpyridinium treatment decreased cell viability and dopamine content, as well as caused apoptotic morphological changes. 1-Methyl-4-phenylpyridinium-induced mitochondrial dysfunction, indicated by inhibition of activity associated with mitochondrial respiratory chain complex I, suggested mitochondrial transmembrane potential collapse and generation of reactive oxygen species. Decreased Bcl-2/Bax ratio and caspase 3 activation were also observed. Rosmarinic acid pretreatment restored the complex I activity of the mitochondrial respiratory chain and partially reversed the other damaging effects of MPP(+). Our results indicate that RA plays a neuroprotective role by ameliorating mitochondrial dysfunction against MPP(+)-induced cell apoptosis and suggest that RA has the potential to be considered an aid for prevention of Parkinson's disease.

Statin use and Parkinson's disease in Denmark

The objective of this study was to investigate whether statin (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor) use is associated with risk of Parkinson's disease (PD) in Denmark. We identified 1,931 patients with a first time diagnosis of PD reported in hospital or outpatient clinic records between 2001 and 2006. We density matched to these patients 9,651 population controls by birth year and sex relying on the Danish population register. For every participant, we identified pharmacy records of statin and anti-Parkinson drug prescriptions since 1995 and before index date from a prescription medication use database for all Danish residents. Whenever applicable, the index dates for cases and their corresponding controls were advanced to the date of first recorded prescription for anti-Parkinson drugs. In our primary analyses, we excluded all statin prescriptions 2-years before PD diagnosis. Employing logistic regression adjusting for age, sex, diagnosis of chronic obstructive pulmonary disease, and Charlson comorbidity, we observed none to slightly inverse associations between PD diagnosis and statin prescription drug use. Inverse associations with statin use were only observed for short-term (<or=1 yrs) statin users (2-year lag OR 0.57; 95% CI 0.36 to 0.89); and suggested at higher intensity statin use (2-year lag OR 0.69; 95% CI 0.45-1.04). No associations were seen among long-term users and no difference by sex, age, or type of statins used (lipophilic/hydrophilic). We found little evidence for a neuroprotective role of statins in PD except for short-term or high intensity users. Yet, further investigations into the contributions of intensity, duration, and lag periods of statin use may still be warranted.

Caffeine protects against disruptions of the blood-brain barrier in animal models of Alzheimer's and Parkinson's diseases

Sporadic Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most common neurodegenerative diseases and as such they represent major public health problems. Finding effective treatments for AD and PD represents an unmet and elusive goal largely because these diseases are chronic and progressive, and have a complicated and ill-understood pathogenesis. Although the underlying mechanisms are not fully understood, caffeine, the most commonly ingested psychoactive drug in the world, has been shown in human and animal studies to be protective against AD and PD. One mechanism implicated in the pathogenesis of AD and PD is blood-brain barrier (BBB) dysfunction and we reported recently that caffeine exerts protective effects against AD and PD at least in part by keeping the BBB intact. The present review focuses on the role of BBB dysfunction in the pathogenesis of AD and PD, caffeine's protective effects against AD and PD, and potential mechanisms whereby caffeine protects against BBB leakage.

Ulcerative colitis exacerbates lipopolysaccharide-induced damage to the nigral dopaminergic system: potential risk factor in Parkinson`s disease

Peripheral inflammation could play a role in the origin and development of certain neurodegenerative disorders. To ascertain this possibility, a model of dopaminergic neurodegeneration based on the injection of the inflammatory agent lipopolysaccharide (LPS) within the substantia nigra was assayed in rats with ulcerative colitis (UC) induced by the ingestion of dextran sulphate sodium. We found an increase in the levels of inflammatory markers from serum (tumor necrosis factor-α, IL-1β, IL-6 and the acute phase protein C-reactive protein) and substantia nigra (tumor necrosis factor-α, IL-1β, IL-6, inducible nitric oxide synthase, intercellular adhesion molecule-1, microglial and astroglial populations) of rats with UC, as well as an alteration of the blood-brain barrier permeability and the loss of dopaminergic neurons. UC reinforced the inflammatory and deleterious effects of LPS. On the contrary, clodronate encapsulated in liposomes (ClodLip), which depletes peripheral macrophages, ameliorated the effect of LPS and UC. Peripheral inflammation might represent a risk factor in the development of Parkinson's disease.