Parkinson's disease and enhanced inflammatory response

Neuroprotective effects of pomegranate (Punica granatum L.) juice and seed extract in paraquat-induced mouse model of Parkinson's disease

BACKGROUND

Paraquat, (PQ), an herbicide that can induce Parkinsonian-like symptoms in rodents and humans. The consumption of phytochemical-rich plants can reduce the risk of chronic illnesses such as inflammation and neurodegenerative diseases. The present study aimed to investigate the protective effects of pomegranate seed extract (PSE) and juice (PJ) against PQ-induced neurotoxicity in mice.

METHODS

Mice were assigned into 4 groups; three groups received PQ (10 mg/kg, i.p.) twice a week for 3 weeks. Two of the PQ-induced groups pretreated with either PSE or PJ. Detection of phytochemicals, total phenolics, and total flavonoids in PSE and PJ was performed. Tyrosine hydroxylase (TH) level was measured in the substantia nigra (SN) by Western blotting technique. Striatal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were detected using high-performance liquid chromatography (HPLC). The levels of adenosine triphosphate (ATP), malondialdehyde (MDA), and the activity of the antioxidant enzymes were estimated in the striatum by colorimetric analysis. Striatal pro-inflammatory and anti-inflammatory markers using enzyme-linked immunosorbent assay (ELISA) as well as DNA fragmentation degree by qualitative DNA fragmentation assay, were evaluated. Real-time polymerase chain reaction (qPCR) assay was performed for the detection of nuclear factor kappa B (NF-кB) gene expression. Moreover, Western blotting analysis was used for the estimation of the cluster of differentiation 11b (CD11b), transforming growth factor β (TGF-β), and glial cell-derived neurotrophic factor (GDNF) levels in the striatum.

RESULTS

Pretreatment with PSE or PJ increased the levels of TH in the SN as well as DA and its metabolite in the striatum that were reduced by PQ injection. PSE and PJ preadministration improved the PQ-induced oxidative stress via a significant reduction of the MDA level and the augmentation of antioxidant enzyme activities. PSE and PJ also significantly downregulated the striatal NF-кB gene expression, reduced the PQ-enhanced apoptosis, decreased the levels of; pro-inflammatory cytokines, CD11b, and TGF-β coupled with a significant increase of; interleukin-10 (IL-10), GDNF, and ATP levels as compared with PQ-treated mice.

CONCLUSIONS

The current study indicated that PSE and PJ consumption may exhibit protective effects against PQ-induced neurotoxicity in mice.

Combined Ubisol-Q10 and Ashwagandha Root Extract Target Multiple Biochemical Mechanisms and Reduces Neurodegeneration in a Paraquat-Induced Rat Model of Parkinson's Disease

Parkinson’s disease (PD) is characterized by progressive neurodegeneration in the substantia nigra (SN) region resulting in loss of movement coordination. Current therapies only provide symptomatic relief, and there is no agent to halt the progression of PD. Previously, Ubisol-Q₁₀, a water-soluble formulation of coenzyme-Q_10, and ethanolic root extract of ashwagandha (ASH) have been shown to inhibit PD pathology in rodent models when used alone. Here, we evaluated the neuroprotective efficacy of oral administration of ASH and Ubisol-Q₁₀ alone and in combination in a paraquat-induced PD rat model. The combined treatment resulted in better-preserved neuron morphology compared to Ubsiol-Q₁₀ or ASH alone. The combination treatment enhanced activation of pro-survival astroglia and inhibited pro-inflammatory microglia. While anti-oxidative effects were seen with both agents, Ubisol-Q₁₀ activated autophagy, whereas ashwagandha showed a better anti-inflammatory response. Thus, the combined treatment caused inhibition of oxidative stress, autophagy activation, inhibition of pro-inflammatory microglia, and activation of pro-survival astroglia. Consequently, paraquat (PQ)-treated rats given the combination treatment in drinking water did not show motor impairment. Based on these interesting observations, the combined treatment containing two well-tolerated natural compounds could be a more effective strategy to halt the progression of PD.

A transition to degeneration triggered by oxidative stress in degenerative disorders

Although the activities of many signaling pathways are dysregulated during the progression of neurodegenerative and muscle degeneration disorders, the precise sequence of cellular events leading to degeneration has not been fully elucidated. Two kinases of particular interest, the growth-promoting Tor kinase and the energy sensor AMPK, appear to show reciprocal changes in activity during degeneration, with increased Tor activity and decreased AMPK activity reported. These changes in activity have been predicted to cause degeneration by attenuating autophagy, leading to the accumulation of unfolded protein aggregates and dysfunctional mitochondria, the consequent increased production of reactive oxygen species (ROS), and ultimately oxidative damage. Here we propose that this increased ROS production not only causes oxidative damage but also ultimately induces an oxidative stress response that reactivates the redox-sensitive AMPK and activates the redox-sensitive stress kinase JNK. Activation of these kinases reactivates autophagy. Because at this late stage, cells have become filled with dysfunctional mitochondria and protein aggregates, which are autophagy targets, this autophagy reactivation induces degeneration. The mechanism proposed here emphasizes that the process of degeneration is dynamic, that dysregulated signaling pathways change over time and can transition from deleterious to beneficial and vice versa as degeneration progresses.

Bee venom attenuates neurodegeneration and motor impairment and modulates the response to L-dopa or rasagiline in a mice model of Parkinson's disease

Objectives

This study aimed to investigate the effect of bee venom, a form of alternative therapy, on rotenone-induced Parkinson's disease (PD) in mice. Moreover, the possible modulation by bee venom of the effect of L-dopa/carbidopa or rasagiline was examined.

Materials and Methods

Rotenone (1.5 mg/kg, subcutaneously; SC) was administered every other day for two weeks and at the same time mice received the vehicle (DMSO, SC), bee venom (0.065, 0.13, and 0.26 mg/kg; intradermal; ID), L-dopa/carbidopa (25 mg/kg, intraperitoneal; IP), L-dopa/carbidopa+bee venom (0.13 mg/kg, ID), rasagiline (1 mg/kg, IP) or rasagiline+bee venom (0.13 mg/kg, ID). Then, wire hanging and staircase tests were performed and mice were euthanized and brains' striata separated. Oxidative stress biomarkers namely, malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), paraoxonase-1 (PON-1), and total antioxidant capacity (TAC) were measured. Additionally, butyrylcholinesterase (BuChE), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), and dopamine (DA) were evaluated. Brain histopathological changes and caspase-3- expression were done.

Results

Bee venom significantly enhanced motor performance and inhibited rotenone-induced oxidative/nitrosative stress, observed as a reduction in both MDA and NO along with increasing GSH, PON-1, and TAC. Besides, bee venom decreased MCP-1, TNF-α, and caspase-3 expression together with an increase in BuChE activity and DA content.

Conclusion

Bee venom alone or in combination with L-dopa/carbidopa or rasagiline alleviated neuronal degeneration compared with L-dopa/carbidopa or rasagiline treatment only. Bee venom via its antioxidant and cytokine reducing potentials might be of value either alone or as adjunctive therapy in the management of PD.

Clinical correlates for immune checkpoint therapy: significance for CNS malignancies

Immune checkpoint inhibitors (ICIs) have revolutionized the field of cancer immunotherapy. Most commonly, inhibitors of PD-1 and CTLA4 are used having received approval for the treatment of many cancers like melanoma, non-small-cell lung carcinoma, and leukemia. In contrast, to date, clinical studies conducted in patients with CNS malignancies have not demonstrated promising results. However, patients with CNS malignancies have several underlying factors such as treatment with supportive medications like corticosteroids and cancer therapies including radiation and chemotherapy that may negatively impact response to ICIs. Although many clinical trials have been conducted with ICIs, measures that reproducibly and reliably indicate that treatment has evoked an effective immune response have not been fully developed. In this article, we will review the history of ICI therapy and the correlative biology that has been performed in the clinical trials testing these therapies in different cancers. It is our aim to help provide an overview of the assays that may be used to gauge immunologic response. This may be particularly germane for CNS tumors, where there is currently a great need for predictive biomarkers that will allow for the selection of patients with the highest likelihood of responding.

Iron Dysregulation and Inflammagens Related to Oral and Gut Health Are Central to the Development of Parkinson's Disease

Neuronal lesions in Parkinson's disease (PD) are commonly associated with α-synuclein (α-Syn)-induced cell damage that are present both in the central and peripheral nervous systems of patients, with the enteric nervous system also being especially vulnerable. Here, we bring together evidence that the development and presence of PD depends on specific sets of interlinking factors that include neuroinflammation, systemic inflammation, α-Syn-induced cell damage, vascular dysfunction, iron dysregulation, and gut and periodontal dysbiosis. We argue that there is significant evidence that bacterial inflammagens fuel this systemic inflammation, and might be central to the development of PD. We also discuss the processes whereby bacterial inflammagens may be involved in causing nucleation of proteins, including of α-Syn. Lastly, we review evidence that iron chelation, pre-and probiotics, as well as antibiotics and faecal transplant treatment might be valuable treatments in PD. A most important consideration, however, is that these therapeutic options need to be validated and tested in randomized controlled clinical trials. However, targeting underlying mechanisms of PD, including gut dysbiosis and iron toxicity, have potentially opened up possibilities of a wide variety of novel treatments, which may relieve the characteristic motor and nonmotor deficits of PD, and may even slow the progression and/or accompanying gut-related conditions of the disease.

The role of brain innate immune response in lysosomal storage disorders: fundamental process or evolutionary side effect?

Sphingolipidoses are diseases caused by mutations in genes responsible for sphingolipid degradation and thereby lead to sphingolipid accumulation. Most sphingolipidoses have a neurodegenerative manifestation characterized by innate immune activation in the brain. However, the role of the immune response in disease progression is ill-understood. In contrast to infectious diseases, immune activation is unable to eliminate the offending agent in sphingolipidoses resulting in ineffective, chronic inflammation. This paradox begs two fundamental questions: Why has this immune response evolved in sphingolipidoses? What role does it play in disease progression? Here, starting from the observation that sphingolipids (SLs) are elevated also in infectious diseases, I discuss the possibility that the activation of the brain immune response by SLs has evolved as a part of the immune response against pathogens and plays no major role in sphingolipidoses.

Oxidative stress mitigation by antioxidants - An overview on their chemistry and influences on health status

The present review paper focuses on the chemistry of oxidative stress mitigation by antioxidants. Oxidative stress is understood as a lack of balance between the pro-oxidant and the antioxidant species. Reactive oxygen species in limited amounts are necessary for cell homeostasis and redox signaling. Excessive reactive oxygenated/nitrogenated species production, which counteracts the organism's defense systems, is known as oxidative stress. Sustained attack of endogenous and exogenous ROS results in conformational and oxidative alterations in key biomolecules. Chronic oxidative stress is associated with oxidative modifications occurring in key biomolecules: lipid peroxidation, protein carbonylation, carbonyl (aldehyde/ketone) adduct formation, nitration, sulfoxidation, DNA impairment such strand breaks or nucleobase oxidation. Oxidative stress is tightly linked to the development of cancer, diabetes, neurodegeneration, cardiovascular diseases, rheumatoid arthritis, kidney disease, eye disease. The deleterious action of reactive oxygenated species and their role in the onset and progression of pathologies are discussed. The results of oxidative attack become themselves sources of oxidative stress, becoming part of a vicious cycle that amplifies oxidative impairment. The term antioxidant refers to a compound that is able to impede or retard oxidation, acting at a lower concentration compared to that of the protected substrate. Antioxidant intervention against the radicalic lipid peroxidation can involve different mechanisms. Chain breaking antioxidants are called primary antioxidants, acting by scavenging radical species, converting them into more stable radicals or non-radical species. Secondary antioxidants quench singlet oxygen, decompose peroxides, chelate prooxidative metal ions, inhibit oxidative enzymes. Moreover, four reactivity-based lines of defense have been identified: preventative antioxidants, radical scavengers, repair antioxidants, and those relying on adaptation mechanisms. The specific mechanism of a series of endogenous and exogenous antioxidants in particular aspects of oxidative stress, is detailed. The final section resumes critical conclusions regarding antioxidant supplementation.

DJ-1 (Park7) affects the gut microbiome, metabolites and the development of innate lymphoid cells (ILCs)

The proper communication between gut and brain is pivotal for the maintenance of health and, dysregulation of the gut-brain axis can lead to several clinical disorders. In Parkinson’s disease (PD) 85% of all patients experienced constipation many years before showing any signs of motor phenotypes. For differential diagnosis and preventive treatment, there is an urgent need for the identification of biomarkers indicating early disease stages long before the disease phenotype manifests. DJ-1 is a chaperone protein involved in the protection against PD and genetic mutations in this protein have been shown to cause familial PD. However, how the deficiency of DJ-1 influences the risk of PD remains incompletely understood. In the present study, we provide evidence that DJ-1 is implicated in shaping the gut microbiome including; their metabolite production, inflammation and innate immune cells (ILCs) development. We revealed that deficiency of DJ-1 leads to a significant increase in two specific genera/species, namely Alistipes and Rikenella. In DJ-1 knock-out (DJ-1^-/-) mice the production of fecal calprotectin and MCP-1 inflammatory proteins were elevated. Fecal and serum metabolic profile showed that malonate which influences the immune system was significantly more abundant in DJ-1^−/− mice. DJ-1 appeared also to be involved in ILCs development. Further, inflammatory genes related to PD were augmented in the midbrain of DJ-1^−/− mice. Our data suggest that metabolites and inflammation produced in the gut could be used as biomarkers for PD detection. Perhaps, these metabolites and inflammatory mediators could be involved in triggering inflammation resulting in PD pathology.

The neuroprotective action of lenalidomide on rotenone model of Parkinson's Disease: Neurotrophic and supportive actions in the substantia nigra pars compacta

Lenalidomide is a centrally active thalidomide analog that has potent anti-inflammatory and antiangiogenic activities. Currently, it is primarily used in the treatment of multiple myeloma and myelodysplastic syndromes. However, recent studies have revealed in addition to neuroprotection and neuromodulation of lenalidomide. Because of this combination of inflammation and neuro-immunogenic properties, lenalidomide is considered as a high potential compound for the treatment of neurodegenerative diseases. Despite intensive research during the last decade, the role of neurotrophic elements in the effect of lenalidomide is still not well understood. Therefore, in the current study, the effects of lenalidomide on neurodegeneration were investigated in a rotenone model of Parkinson's disease (PD) rat model. The PD rat model was generated by rotenone injection into the substantia nigra pars compacta (SNpc). After validation of the PD model, the rats were treated with lenalidomide (100 mg/kg) for 28 days. Our data shows that lenalidomide alleviated rotenone-induced motor impairments and deficits in dopamine-related behaviors and resulted in increased levels of tumor necrosis factor-α and calcium-binding protein B in the SNpc. Moreover, chronic lenalidomide treatment resulted increase in transforming growth factor immunoreactivity and brain derived neurotrophic factor expression in the SNPc. In addition, chronic treatment mitigated tyrosine hydroxylase expression prevented the rotenone-induced decrease in dopamine levels, and consequently a decrease in caspase-3/9 immunoreactivity. This thus shows that chronic lenalidomide treatment improves neuronal survival. Together with our data demonstrate that lenalidomide, in addition to its anti-inflammatory and immunomodulatory actions, is also capable of increasing neurotrophic factors in the SNpc, thereby preventing rotenone-induced motor impairments.

Sex specific inflammatory profiles of cerebellar mitochondria are attenuated in Parkinson's disease

Response to inflammation is a key determinant in many diseases and their outcomes. Diseases that commonly affect older people are frequently associated with altered inflammatory processes. Neuroinflammation has been described in Parkinson's disease (PD) brain. PD is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta and at the sub-cellular level, mitochondrial dysfunction is a key feature. However, there is evidence that a different region of the brain, the cerebellum, is involved in the pathophysiology of PD. We report relative levels of 40 pro- and anti-inflammatory cytokines measured in PD and control cerebellar mitochondria. These data were obtained by screening cytokine antibody arrays. In parallel, we present concentrations of 29 oxylipins and 4 endocannabinoids measured in mitochondrial fractions isolated from post-mortem PD cerebellum with age and sex matched controls. Our oxylipin and endocannabinoid data were acquired via quantitation by LC-ESI-MS/MS. The separate sample sets both show there are clearly different inflammatory profiles between the sexes in control samples. Sex specific profiles were not maintained in cerebellar mitochondria isolated from PD brains.

Study of the Link Between Neuronal Death, Glial Response, and MAPK Pathway in Old Parkinsonian Mice

Background: Parkinson’s disease (PD) is described as an age-related neurodegenerative disorder. However, the vast majority of research is carried out using experimental models of young animals lacking the implications of the decline processes associated with aging. It has been suggested that several molecular pathways are involved in the perpetuation of the degeneration and the neuroinflammation in PD. Among others, mitogen-activated protein kinases (MAPKs) have been highly implicated in the development of PD, and regulating components of their activity are indicated as promising therapeutic targets.

Methods: To further define how MAPKs expression is related to the glial response and neuronal cell death, Parkinsonism was induced under an acute regimen in old mice. Moreover, the sacrifice was carried out at different time points (4, 8, 24, and 48 h) after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) injections to describe the early dynamic changes over time produced by the intoxication.

Results: The results revealed that neuronal death increases as glial response increases in the nigrostriatal pathway. It was observed that both processes increase from 4 h in the ventral mesencephalon (VM), and neuronal death becomes significant at 48 h. In the striatum, they were significantly increased from 48 h after the MPTP administration compared with that in the control mice. Moreover, the p-ERK levels decrease, while phospho-p38 expression increases specifically in the striatum at 48 h after MPTP intoxication.

Conclusions: The importance of these data lies in the possibility of elucidating the underlying mechanisms of neurodegenerative processes under aging conditions to provide knowledge for the search of solutions that slow down the progression of PD.

Astrocytes in Parkinson's disease: from preclinical assays to in vivo imaging and therapeutic probes

Parkinson's disease (PD) is increasingly thought to be associated with glial pathology. Recently, research in neurodegenerative disorders has applied a greater focus to better understanding the role of astrocytes in the disease pathophysiology. In this article, we review results from the latest preclinical and clinical work, including functional imaging studies on astrocytes in PD and highlight key molecules that may prove valuable as biomarkers. We discuss how astrocytes may contribute to the initiation and progression of PD. We additionally present trials of investigational medicinal products and the current background for the design of future clinical trials.

Maternal Hyperhomocysteinemia Induces Neuroinflammation and Neuronal Death in the Rat Offspring Cortex

Maternal hyperhomocysteinemia is one of the common complications of pregnancy that causes offspring cognitive deficits during postnatal development. In the present work, we evaluated the effect of prenatal hyperhomocysteinemia on structural and ultrastructural organization, neuronal and glial cell number, apoptosis (caspase-3 content and activity), inflammatory markers (tumor necrosis factor-α, interleukin-6, and interleukin-1β), and p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation in the offspring brain cortex in early ontogenesis. Wistar female rats received methionine (0.6 g/kg body weight) by oral administration during pregnancy. Histological and biochemical analyses of 5- and 20-day-old pups' cortical tissue were performed. Lysosome accumulation and other neurodegenerative changes in neurons of animals with impaired embryonic development were investigated by electron microscopy. Neuronal staining (anti-NeuN) revealed a reduction in neuronal number, accompanied by increasing of caspase-3 active form protein level and activity. Maternal hyperhomocysteinemia also elevated the number of astroglial and microglial cells and increased expression of interleukin-1β and p38 MAPK phosphorylation, which indicates the development of neuroinflammatory processes.

Down regulation of miR-218, miR-124, and miR-144 relates to Parkinson's disease via activating NF-κB signaling

Parkinson's disease (PD) is a neurological degenerative disorder that is partially induced by inflammation in the neural system. To explore the roles of disordered microRNAs in the development of PD, we screened 10 miRNAs in the brain samples of 15 postmortem PD patients and 10 postmortem healthy controls by qRT-PCR. The direct targets of miRNAs were predicted by informatics tools and further confirmed by dual luciferase assay and immunoblotting. The function of miRNAs in regulating NF-κB/p65 translocation was examined by immunoblotting, and the overactivation of NF-κB signaling was examined by ELISA. The relationship between dysregulated miRNAs and cytokines was analyzed by correlation analysis. Three miRNAs were found to be reduced in the brains of patients with PD. KPNB1, KPNA3, and KPNA4 were identified as direct targets of miR-218, miR-124, and miR-144. Additionally, KPNA3 was identified as a direct target of miR-124, and KPNA4 was a direct target of both miR-124 and miR-218. The p65 translocation from the cytoplasm to the nucleus was repressed by miR-124, miR-218, and miR-144 in the SH-SY5Y cells. The NF-κB signaling pathway was overactivated after miRNA inhibitor transfection. The upregulation of KPNB1, KPNA3, and KPNA4 in the brain samples of PD patients was confirmed by immunoblotting, and negative correlations were found between dysregulated miRNAs and cytokines. In conclusion, we identified that the downregulation of miR-218, miR-124, and miR-144 in the brain was related to PD via activation of NF-κB signaling, helping to unveil the role played by dysregulated miRNAs in the pathogenesis of PD and provide new potential targets for PD treatment.

Transgenic Overexpression of GPNMB Protects Against MPTP-Induced Neurodegeneration

Parkinson's disease (PD) is a progressive neurodegenerative disease highlighted by a marked loss of dopaminergic cell loss and motor disturbances. Currently, there are no drugs that slow the progression of the disease. A myriad of factors have been implicated in the pathogenesis and progression of PD including neuroinflammation. Although anti-inflammatory agents are being evaluated as potential disease-modifying therapies for PD, none has proven effective to date, suggesting that new and novel targets are needed. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a transmembrane glycoprotein that has recently been shown to reduce inflammation in astrocytes and to be increased in post-mortem PD brain samples. Here we show that transgenic overexpression of GPNMB protects against dopaminergic neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropridine mouse model of Parkinson's disease. Furthermore, GPNMB overexpression reduces gliosis and prevented microglial morphological changes following MPTP treatment compared with wild-type MPTP-treated mice. Additionally, recombinant GPNMB attenuates LPS-induced inflammation in primary mouse microglia. These results suggest a neuroprotective and anti-inflammatory role for GPNMB and warrant further investigation for GPNMB as a novel therapy for PD.

Platycodin D inhibits MPP+-induced inflammatory response in BV-2 cells through the TLR4/MyD88/NF-κB signaling pathway

Parkinson's disease is a common progressive neurodegenerative disorder associated with inflammation. Platycodin D (PLD) is a triterpenesaponin that has anti-inflammatory and neuro-protective effects. However, the role of PLD in Parkinson's disease has not been fully investigated. In the current study, we investigated the effect of PLD on 1-methyl-4-phenylpyridinium (MPP⁺)-induced inflammatory response in BV-2 cells. Our results showed that PLD treatment improved the cell viability of MPP⁺-induced BV-2 cells. PLD significantly inhibited the levels of inflammatory mediators including nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in MPP⁺-treated BV-2 cells. The increased productions of inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and IL-6 in MPP⁺-treated BV-2 cells were also suppressed by PLD. Furthermore, PLD inhibited the activation of TLR4/MyD88/NF-κB pathway in MPP⁺-treated BV-2 cells. Overexpression of TLR4 reversed the protective effects of PLD on MPP⁺-treated BV-2 cells. Collectively, PLD protected BV-2 cells from MPP⁺-induced inflammatory response via regulating the TLR4-MyD88-NF-κB signaling pathway.

Downregulation of lncRNA BACE1-AS improves dopamine-dependent oxidative stress in rats with Parkinson's disease by upregulating microRNA-34b-5p and downregulating BACE1

Objective: Long noncoding RNAs (lncRNAs) have already been proposed to function in Parkinson's disease (PD). However, the role of lncRNA BACE1-AS in PD has never been discussed. This study aims to examine the mechanism of BACE1-AS on oxidative stress injury of dopaminergic neurons in PD rats.Methods: Rat models of PD were established through the injection of 6-hydroxydopamine. The rotation of rats was induced by intraperitoneal injection of apomorphine, and number of rotations per minute was detected. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), glutamic acid (Glu), dopamine (DA), tyrosine hydroxylase (TH), α-synuclein and inducible nitric oxide synthase (iNOS) in the substantia nigra of rats in each group were detected. Apoptosis and pathological changes in the substantia nigra were also observed. BACE1-AS, miR-34b-5p, BACE1, Bax and Bcl-2 expression in the substantia nigra were detected. The binding of BACE1-AS and miR-34b-5p and the targeting relationship of miR-34b-5p and BACE1 were further determined.Results: Downregulated BACE1-AS reduced iNOS, α-synuclein and Glu levels and elevated DA and TH levels in the substantia nigra of PD rats. Downregulated BACE1-AS repressed apoptosis and oxidative stress injury in the substantia nigra neurons of PD rats. BACE1-AS specifically bound to miR-34b-5p. BACE1 was a direct target gene of miR-34b-5p.Conclusion: Collectively, our study reveals that downregulation of lncRNA BACE1-AS inhibits iNOS activation in the substantial nigra and improve oxidative stress injury in PD rats by upregulating miR-34b-5p and downregulating BACE1.

[Immunological aspects of Parkinson's disease]

The review summarizes information on immunological disorders in Parkinson's disease (PD). The data on neuroinflammation associated with degeneration of the medial substantia nigra cells are presented. It is pointed out that innate and adaptive immunity cells are involved in the process of neuroinflammation. The authors analyze the cytokine level in the brain, cerebrospinal fluid and peripheral blood as well as the relationship between neuroinflammation and neuron dysfunction and provide information on immunological disorders in people with PD and animal models of PD. Specific features of PD models and data on blood-brain barrier damage and evidence of autoimmune inflammation in PD are presented. Identification of PD preclinical markers, including cytokines, HLA-DR and HLA-DQ antigens, autoantibodies, etc, is discussed. Pre-symptomatic diagnosis of PD, prevention and treatment at the pre-symptomatic stage could lead to interruption or slowdown the neurons death.

Lipopolysaccharide animal models of Parkinson's disease: Recent progress and relevance to clinical disease

Parkinson's disease (PD) is one of the most common neurodegenerative movement disorders which is characterised neuropathologically by progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of Lewy bodies (made predominately of α-synuclein) in the surviving neurons. Animal models of PD have improved our understanding of the disease and have played a critical role in the development of neuroprotective agents. Neuroinflammation has been strongly implicated in the pathogenesis of PD, and recent studies have used lipopolysaccharide (LPS), a component of gram-negative bacteria and a potent activator of microglia cells, to mimic the inflammatory events in clinical PD. Modulating the inflammatory response could ameliorate PD associated complications and thus, it is essential to understand the extent to which LPS models reflect human PD. This review will outline the routes of administration of LPS such as stereotaxic, systemic and intranasal, their ability to recapitulate neuropathological markers of PD, and mechanisms of LPS induced toxicity. We will also discuss the ability of the models to replicate motor symptoms and non-motor symptoms of PD such as gastrointestinal dysfunction, olfactory dysfunction, anxiety, depression and cognitive dysfunction.

Regulation of BDNF-TrkB Signaling and Potential Therapeutic Strategies for Parkinson's Disease

Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase receptor type B (TrkB) are widely distributed in multiple regions of the human brain. Specifically, BDNF/TrkB is highly expressed and activated in the dopaminergic neurons of the substantia nigra and plays a critical role in neurophysiological processes, including neuro-protection and maturation and maintenance of neurons. The activation as well as dysfunction of the BDNF-TrkB pathway are associated with neurodegenerative diseases. The expression of BDNF/TrkB in the substantia nigra is significantly reduced in Parkinson's Disease (PD) patients. This review summarizes recent progress in the understanding of the cellular and molecular roles of BNDF/TrkB signaling and its isoform, TrkB.T1, in Parkinson's disease. We have also discussed the effects of current therapies on BDNF/TrkB signaling in Parkinson's disease patients and the mechanisms underlying the mutation-mediated acquisition of resistance to therapies for Parkinson's disease.

Neuroprotective Effect of Optimized Yinxieling Formula in 6-OHDA-Induced Chronic Model of Parkinson's Disease through the Inflammation Pathway

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra (SN)-striatum circuit, which is associated with glial activation and consequent chronic neuroinflammation. Optimized Yinxieling Formula (OYF) is a Chinese medicine that exerts therapeutical effect and antiinflammation property on psoriasis. Our previous study has proven that pretreatment with OYF could regulate glia-mediated inflammation in an acute mouse model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Given that PD is a chronic degeneration disorder, this study applied another PD animal model induced by striatal injection of 6-hydroxydopamine (6-OHDA) to mimic the progressive damage of the SN-striatum dopamine system in rats. The OYF was administrated in the manner of pretreatment plus treatment. The effects of the OYF on motor behaviors were assessed with the apomorphine-induced rotation test and adjusting steps test. To confirm the effect of OYF on dopaminergic neurons and glia activation in this model, we analyzed the expression of tyrosine hydroxylase (TH) and glia markers, ionized calcium-binding adapter molecule 1 (Iba-1), and glial fibrillary acidic protein (GFAP) in the SN region of the rat PD model. Inflammation-associated factors, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), were further evaluated in this model and in interferon-γ- (INF-γ-) induced murine macrophages RAW264.7 cells. The results from the in vivo study showed that OYF reversed the motor behavioral dysfunction in 6-OHDA-induced PD rats, upregulated the TH expression, decreased the immunoreactivity of Iba-1 and GFAP, and downregulated the mRNA levels of TNF-α and COX-2. The OYF also trended to decrease the mRNA levels of IL-1β and iNOS in vivo. The results from the in vitro study showed that OYF significantly decreased the mRNA levels of TNF-α, IL-1β, IL-6, iNOS, and COX-2. Therefore, this study suggests that OYF exerts antiinflammatory effects, which might be related to the protection of dopaminergic neurons in 6-OHDA-induced chronic neurotoxicity.

TLR4 deficiency has a protective effect in the MPTP/probenecid mouse model of Parkinson's disease

Parkinson’s disease (PD) is a multifactorial disorder characterized by progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and the presence of Lewy bodies (LBs) consisting of misfolded α-synuclein protein. The etiology of PD is still not clear but systemic inflammation is proved to trigger and exacerbate DA neurons degeneration. Toll-like receptor 4 (TLR4) is a pattern-recognition receptor (PRR) and plays a major role in promoting the host immune. TLR4-mediated signal pathways induce the release of many inflammatory cytokines. It is reasonable to hypothesize that TLR4 is the mediator in microglia contributing to the damage of DA neurons in the SNpc. In this study, we evaluated the role of TLR4 in the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/probenecid mouse model. Both TLR4-deficient and wild-type (WT) mice were injected with probenecid (250 mg/kg, i.p.) followed by injection of MPTP (25 mg/kg, s.c.) every 4 days for 10 times. From D43 to D47, the behavioral performance in pole test and wire hang test was assessed. Then the mice were euthanized, and SN and striatum were dissected out for biochemical tests. We showed that compared with MPTP-treated WT mice, TLR4 deficiency significantly attenuated MPTP-induced motor deficits and TH-protein expression reduction in SNpc and striatum, suppressed MPTP-induced α-synuclein abnormality and neuroinflammation mediated through oxidative stress, glial activation, NF-κB and the NLRP3 inflammasome signaling pathways. These findings highlight the neuroprotective effect of TLR4-pathways in the chronic MPTP-induced PD mouse model.

Glia Maturation Factor and Mast Cell-Dependent Expression of Inflammatory Mediators and Proteinase Activated Receptor-2 in Neuroinflammation

Parkinson's disease (PD) is characterized by the presence of inflammation-mediated dopaminergic neurodegeneration in the substantia nigra. Inflammatory mediators from activated microglia, astrocytes, neurons, T-cells and mast cells mediate neuroinflammation and neurodegeneration. Administration of neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induces PD like motor deficits in rodents. 1-methyl-4-phenylpyridinium (MPP+), a toxic metabolite of MPTP activates glial cells, neurons and mast cells to release neuroinflammatory mediators. Glia maturation factor (GMF), mast cells and proteinase activated receptor-2 (PAR-2) are implicated in neuroinflammation. Alpha-synuclein which induces neurodegeneration increases PAR-2 expression in the brain. However, the exact mechanisms are not yet understood. In this study, we quantified inflammatory mediators in the brains of MPTP-administered wild type (Wt), GMF-knockout (GMF-KO), and mast cell knockout (MC-KO) mice. Additionally, we analyzed the effect of MPP+, GMF, and mast cell proteases on PAR-2 expression in astrocytes and neurons in vitro. Results show that the levels of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and the chemokine (C-C motif) ligand 2 (CCL2) were lesser in the brains of GMF-KO mice and MC-KO mice when compared to Wt mice brain after MPTP administration. Incubation of astrocytes and neurons with MPP+, GMF, and mouse mast cell protease-6 (MMCP-6) and MMCP-7 increased the expression of PAR-2. Our studies show that the absence of mast cells and GMF reduce the expression of neuroinflammatory mediators in the brain. We conclude that GMF along with mast cell interactions with glial cells and neurons during neuroinflammation can be explored as a new therapeutic target for PD and other neuroinflammatory disorders.

Initiation and Transmission of α-Synuclein Pathology in Parkinson's Disease

The pathogenesis of Parkinson's disease (PD) involves the accumulation of aggregated forms of α-synuclein in the body. The location for the initiation of misfolded forms of α-synuclein is now a contentious issue, what was once thought to be a disease of the central nervous system (CNS) now appears to involve multiple organs in the body. In particular, the two regions in the body where the nervous system is exposed to the environment, the olfactory bulb and the enteric nervous system, are now thought to play an important role in the initial phase of the disease. Epidemiological studies point to the gastrointestinal tract, including the appendix, as a potential site for the misfolding and transmission of α-synuclein, with the vagus nerve providing a conduit between the gut and brain. A growing body of animal studies also support this pathway, implicating the transmission of pathological α-synuclein from outside the CNS in the development of PD.

Enriched Environmental Conditions Modify the Gut Microbiome Composition and Fecal Markers of Inflammation in Parkinson's Disease

Recent findings suggest an implication of the gut microbiome in Parkinson's disease (PD) patients. PD onset and progression has also been linked with various environmental factors such as physical activity, exposure to pesticides, head injury, nicotine, and dietary factors. In this study, we used a mouse model, overexpressing the complete human SNCA gene (SNCA-TG mice) modeling familial and sporadic forms of PD to study whether environmental conditions such as standard vs. enriched environment changes the gut microbiome and influences disease progression. We performed 16S rRNA DNA sequencing on fecal samples for microbiome analysis and studied fecal inflammatory calprotectin from the colon of control and SNCA-TG mice kept under standard environment (SE) and enriched environment (EE) conditions. The overall composition of the gut microbiota was not changed in SNCA-TG mice compared with WT in EE with respect to SE. However, individual gut bacteria at genus level such as Lactobacillus sp. was a significant changed in the SNCA-TG mice. EE significantly reduced colon fecal inflammatory calprotectin protein in WT and SNCA-TG EE compared to SE. Moreover, EE reduces the pro-inflammatory cytokines in the feces and inflammation inducing genes in the colon. Our data suggest that an enriched social environment has a positive effect on the induction of SNCA mediated inflammation in the intestine and by modulating anti-inflammatory gut bacteria.

Influence of intranasal exposure of MPTP in multiple doses on liver functions and transition from non-motor to motor symptoms in a rat PD model

Besides the effects on the striatum, the impairment of visceral organs including liver functions has been reported in Parkinson's disease (PD) patients. However, it is yet unclear if liver functions are affected in the early stage of the disease before the motor phase has appeared. The aim of our present study was thus to assess the effect of intranasal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in different doses on striatum and liver functions. Deterioration of non-motor activities appeared on single exposure to MPTP along with rise in striatum oxidative stress and decline in antioxidant levels. Decreases in dopamine, noradrenaline, and GABA and increase in serotonin were detected in striatum. Motor coordination was impaired with a single dose of MPTP, and with repeated MPTP exposure, there was further significant impairment. Locomotor activity was affected from second exposure of MPTP, and the impairment increased with third MPTP exposure. Impairment of liver function through increase in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels was observed after first MPTP insult, and it worsened with second and third administrations. First administration of MPTP triggered systemic inflammation showing significant increase in inflammatory markers in the liver. Our data shows for the first time that an intranasal route of entry of MPTP affects liver from the non-motor phase of PD itself, occurring concomitantly with the reduction of striatal dopamine. It also suggests that a single dose is not enough to bring about progression of the disease from non-motor to locomotor deficiency, and a repeated dose is needed to establish the motor severity phase in the rat intranasal MPTP model.

Association of polymorphisms in the MCP-1 and CCR2 genes with the risk of Parkinson's disease

Studies investigating the impact of polymorphisms on monocyte chemotactic protein-1 (MCP-1) and CC chemokine receptor (CCR2) on the susceptibility of Parkinson's disease (PD) have reported inconsistent results. Owing to mixed and inconclusive results, we conducted a meta-analysis to systematically summarize and clarify the association between the two gene polymorphisms and PD risk. We performed a meta-analysis of five eligible studies to summarize the data describing the association between PD risk and polymorphisms in MCP-1 A2518G and CCR2 V64I. The association was evaluated by calculating the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs). A significant increased risk of PD was observed in the MCP-1 A2518G polymorphism in allele model (G vs. A: OR 1.12, 95% CI 1.01-1.25, p = 0.03). The dominant model of MCP-1 A2518G genotype showed no significant association with PD risk, while the risk tendency was increased (AG + GG vs. AA: OR 1.20, 95% CI 1.00-1.42, p = 0.05). In addition, CCR2 V64I polymorphism showed no significant association with PD risk (I vs. V: OR 0.33, 95% CI 0.06-1.92, p = 0.22; VI + II vs. VV: OR 1.00, 95% CI 0.83-1.21, p = 0.99). In subgroup analysis by ethnicity, no significant difference was found in both Caucasians and Asians between CCR2 V64I polymorphism and PD risk, while a significant statistical association was identified in Asians between MCP-1 A2518G polymorphism and PD risk. When the data were stratified by study area, the increased risk of PD was observed only in studies conducted in China. In summary, the present meta-analysis suggests that genetic polymorphisms of MCP-1 A2518G may influence the susceptibility of PD in Asian countries, especially in China. However, CCR2 V64I polymorphism is not correlated with PD risk. The results should be interpreted with caution due to limited sample and heterogeneity. Large scale and well-designed studies are needed to validate our findings.

Can krill oil be of use for counteracting neuroinflammatory processes induced by high fat diet and aging?

Most neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, demonstrate preceding or on-going inflammatory processes. Therefore, discovering effective means of counteracting detrimental inflammatory mediators in the brain could help alter aging-related disease onset and progression. Fish oil and marine-derived omega-3, long-chain polyunsaturated fatty acids (LC n-3) have shown promising anti-inflammatory effects both systemically and centrally. More specifically, krill oil (KO), extracted from small Antarctic crustaceans, is an alternative type of LC n-3 with reported health benefits including improvement of spatial memory and learning, memory loss, systemic inflammation and depression symptoms. Similar to the more widely studied fish oil, KO contains the long chain fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are essential for basic brain functions. Moreover, the phospholipid bound nature of fatty acids found in KO improves bioavailability and efficiency of absorption, thus supporting the belief that KO may offer a superior method of dietary n-3 delivery. Finally, KO contains astaxanthin, an antioxidant capable of reducing potentially excessive oxidative stress and inflammation within the brain. This review will discuss the potential benefits of KO over other marine-based LC n-3 on brain inflammation and cognitive function in the context of high fat diets and aging.

The Neuroprotective Effects of Astaxanthin: Therapeutic Targets and Clinical Perspective

As the leading causes of human disability and mortality, neurological diseases affect millions of people worldwide and are on the rise. Although the general roles of several signaling pathways in the pathogenesis of neurodegenerative disorders have so far been identified, the exact pathophysiology of neuronal disorders and their effective treatments have not yet been precisely elucidated. This requires multi-target treatments, which should simultaneously attenuate neuronal inflammation, oxidative stress, and apoptosis. In this regard, astaxanthin (AST) has gained growing interest as a multi-target pharmacological agent against neurological disorders including Parkinson’s disease (PD), Alzheimer’s disease (AD), brain and spinal cord injuries, neuropathic pain (NP), aging, depression, and autism. The present review highlights the neuroprotective effects of AST mainly based on its anti-inflammatory, antioxidative, and anti-apoptotic properties that underlies its pharmacological mechanisms of action to tackle neurodegeneration. The need to develop novel AST delivery systems, including nanoformulations, targeted therapy, and beyond, is also considered.

Comparison of the Protective Effects of Bee Venom Extracts with Varying PLA2 Compositions in a Mouse Model of Parkinson's Disease

Bee venom contains a number of pharmacologically active components, including enzymes and polypeptides such as phospholipase A₂ (PLA₂) and melittin, which have been shown to exhibit therapeutic benefits, mainly via attenuation of inflammation, neurotoxicity, and nociception. The individual components of bee venom may manifest distinct biological actions and therapeutic potential. In this study, the potential mechanisms of action of PLA₂ and melittin, among different compounds purified from honey bee venom, were evaluated against Parkinson’s disease (PD). Notably, bee venom PLA₂ (bvPLA₂), but not melittin, exhibited neuroprotective activity against PD in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP-induced behavioral deficits were also abolished after bvPLA₂ treatment, depending on the PLA₂ content. Further, bvPLA₂ administration activated regulatory T cells (Tregs) while inhibiting inflammatory T helper (Th) 1 and Th17 cells in the MPTP mouse model of PD. These results indicate that bvPLA₂, but not melittin, protected against MPTP and alleviated inflammation in PD. Thus, bvPLA₂ is a promising and effective therapeutic agent in Parkinson’s disease.

Environmental neurotoxicant-induced dopaminergic neurodegeneration: a potential link to impaired neuroinflammatory mechanisms

With the increased incidence of neurodegenerative diseases worldwide, Parkinson's disease (PD) represents the second-most common neurodegenerative disease. PD is a progressive multisystem neurodegenerative disorder characterized by a marked loss of nigrostriatal dopaminergic neurons and the formation of Lewy pathology in diverse brain regions. Although the mechanisms underlying dopaminergic neurodegeneration remain poorly characterized, data from animal models and postmortem studies have revealed that heightened inflammatory responses mediated via microglial and astroglial activation and the resultant release of proinflammatory factors may act as silent drivers of neurodegeneration. In recent years, numerous studies have demonstrated a positive association between the exposure to environmental neurotoxicants and the etiology of PD. Although it is unclear whether neuroinflammation drives pesticide-induced neurodegeneration, emerging evidence suggests that the failure to dampen neuroinflammatory mechanisms may account for the increased vulnerability to pesticide neurotoxicity. Furthermore, recent studies provide additional evidence that shifts the focus from a neuron-centric view to glial-associated neurodegeneration following pesticide exposure. In this review, we propose to summarize briefly the possible factors that regulate neuroinflammatory processes during environmental neurotoxicant exposure with a focus on the potential roles of mitochondria-driven redox mechanisms. In this context, a critical discussion of the data obtained from experimental research and possible epidemiological studies is included. Finally, we hope to provide insights on the pivotal role of exosome-mediated intercellular transmission of aggregated proteins in microglial activation response and the resultant dopaminergic neurodegeneration after exposure to pesticides. Collectively, an improved understanding of glia-mediated neuroinflammatory signaling might provide novel insights into the mechanisms that contribute to neurodegeneration induced by environmental neurotoxicant exposure.

Mast Cells in Neurodegenerative Disease

Neurodegenerative diseases affect millions of people worldwide, yet there are currently no effective treatments. Because risk of neurodegenerative disease substantially increases with age, greater life expectancy with a concomitant aging population means more individuals will be affected in the coming decades. Thus, there is an urgent need for understanding the mechanisms driving neurodegenerative diseases in order to develop improved treatment strategies. Inflammation in the nervous system, termed “neuroinflammation,” has become increasingly recognized as being associated with neurodegenerative diseases. Early attention focused primarily on morphological changes in astrocytes and microglia; however, brain and CNS resident mast cells are now receiving attention as a result of being “first responders” to injury. Mast cells also exert profound effects on their microenvironment and neighboring cells including behavior and/or activation of astrocytes, microglia, and neurons, which, in turn, are implicated in neuroinflammation, neurogenesis and neurodegeneration. Mast cells also affect disruption/permeability of the blood brain barrier enabling toxin and immune cell entry exacerbating an inflammatory microenvironment. Here, we discuss the roles of mast cells in neuroinflammation and neurodegeneration with a focus on development and progression of four prominent neurodegenerative diseases: Alzheimer’s Disease, Parkinson’s Disease, Amyotrophic Lateral Sclerosis, and Huntington’s Disease.

5-(3,4-Difluorophenyl)-3-(6-methylpyridin-3-yl)-1,2,4-oxadiazole (DDO-7263), a novel Nrf2 activator targeting brain tissue, protects against MPTP-induced subacute Parkinson's disease in mice by inhibiting the NLRP3 inflammasome and protects PC12 cells against oxidative stress

Parkinson's disease (PD) is the second most common aging-related neurodegenerative disease worldwide. Oxidative stress and neuroinflammation are critical events in the degeneration of dopaminergic neurons in PD. In this study, we found that DDO-7263, a novel Nrf2-ARE activator reported by us, has ideal therapeutic effects on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease in mice. DDO-7263 improved the behavioral abnormalities induced by MPTP in mice, significantly attenuated chemically induced dopaminergic neuron loss of tyrosine hydroxylase (TH) in the substantia nigra (SN) and striatum of the mouse brain and inhibited the secretion of inflammatory factors. In addition, DDO-7263 protected PC12 neurons from H₂O₂-induced oxidative damage. The neuroprotective effects of DDO-7263 were confirmed both in vitro and in vivo models. Further studies showed that the neuroprotective effect of DDO-7263 was mediated by the activation of Nrf2-ARE signaling pathway and the inhibition of NLRP3 inflammasome activation. DDO-7263 induced NLRP3 inflammasome inhibition is dependent on Nrf2 activation. This conclusion was also verified in THP-1-derived macrophages (THP-Ms). DDO-7263 significantly inhibited NLRP3 activation, cleaved caspase-1 production and IL-1β protein expression in ATP-LPS-exposed THP-Ms cells. The pharmacokinetic parameters and tissue distribution results indicated that DDO-7263 has a brain tissue targeting function. All these lines of evidence show that DDO-7263 has ideal therapeutic effects on neurodegenerative diseases such as PD.

Metabolic treatment of syndrome linked with Parkinson's disease and hypothalamus pituitary gonadal hormones by turmeric curcumin in Bisphenol-A induced neuro-testicular dysfunction of wistar rat

The metabolic shift in cholinesterase activity and inhibitor of hypothalamus pituitary gonadal hormones were hypothesized as resultant effect of Parkinson's disease (PD) which is clinically characterized by a movement disorder. This study therefore examined the effect of turmeric curcumin (CUR) on index of PD, acetylcholine esterase activity and disorder of hypothalamus pituitary gonadal hormone (HPGH) in Bisphenol-A induced injury using animal model. Forty adult male albino rats were randomly distributed into five (n = 8) groups. Group I: vehicle control (olive oil 0.5 ml), Group II was given 50 mg/kg of BPA only, Group III was given 50 mg/kg BPA + 50 mg/kg curcumin, Group IV was given 50 mg/kg BPA + 100 mg/kg curcumin and Group V was administered 50 mg/kg of curcumin only for 14 days. The study examined the effect of curcumin on acetylcholineesterase (AChE) activity, nitric oxide radical (NO•) production, HPGH (LH, FSH and testosterone), MDA level, antioxidant enzymes (SOD and CAT), in BPA induced male rat. Sperm parameters were similarly examined. The animals induced with BPA exhibited impairment to striatum, leydig cells and sertoli cells by depleting LH, FSH, testosterone and spermatozoa with reduced AChE activity and significant (p < 0.05) alteration in cerebral enzymatic antioxidants. Locomotive activity was impeded followed by the increase of brain NO• level (marker of pro-inflammation). Therapeutically, CUR promoted hypothalamus-pituitary-testicular hormones via modulation of AChE and locomotive activities, reduction of intracellular NO• level, prevention of striatum-endocrine injury as well as oxidative damage. Hence, CUR abolished HPGH dysfunction linked with PD mediated by BPA in rat.

Low-Grade Inflammation Aggravates Rotenone Neurotoxicity and Disrupts Circadian Clock Gene Expression in Rats

A single injection of LPS produced low-grade neuroinflammation leading to Parkinson's disease (PD) in mice several months later. Whether such a phenomenon occurs in rats and whether such low-grade neuroinflammation would aggravate rotenone (ROT) neurotoxicity and disrupts circadian clock gene/protein expressions were examined in this study. Male rats were given two injections of LPS (2.5-7.5 mg/kg), and neuroinflammation and dopamine neuron loss were evident 3 months later. Seven months after a single LPS (5 mg/kg) injection, rats received low doses of ROT (0.5 mg/kg, sc, 5 times/week for 4 weeks) to examine low-grade neuroinflammation on ROT toxicity. LPS plus ROT produced more pronounced non-motor and motor dysfunctions than LPS or ROT alone in behavioral tests, and decreased mitochondrial complex 1 activity, together with aggravated neuroinflammation and neuron loss. The expressions of clock core genes brain and muscle Arnt-like protein-1 (Bmal1), locomotor output cycles kaput (Clock), and neuronal PAS domain protein-2 (Npas2) were decreased in LPS, ROT, and LPS plus ROT groups. The expressions of circadian feedback genes Periods (Per1 and Per2) were also decreased, but Cryptochromes (Cry1 and Cry2) were unaltered. The circadian clock target genes nuclear receptor Rev-Erbα (Nr1d1), and D-box-binding protein (Dbp) expressions were also decreased. Consistent with the transcript levels, circadian clock protein BMAL1, CLOCK, NR1D1, and DBP were also decreased. Thus, LPS-induced chronic low-grade neuroinflammation potentiated ROT neurotoxicity and disrupted circadian clock gene/protein expression, suggesting a role of disrupted circadian in PD development and progression. Graphical Abstract ᅟ.

Parkin clearance of dysfunctional mitochondria regulates ROS levels and increases survival of human chondrocytes

OBJECTIVE

Mitochondrial dysfunction, oxidative stress and chondrocyte death are important contributors to the development and pathogenesis of osteoarthritis (OA). In this study, we determined the expression and role of Parkin in the clearance of damaged/dysfunctional mitochondria, regulation of reactive oxygen species (ROS) levels and chondrocyte survival under pathological conditions.

METHODS

Human chondrocytes were from the unaffected area of knee OA cartilage (n = 12) and were stimulated with IL-1β to mimic pathological conditions. Mitochondrial membrane depolarization and ROS levels were determined using specific dyes and flow cytometry. Autophagy was determined by Western blotting for ATG5, Beclin1, immunofluorescence staining and confocal microscopy. Gene expression was determined by RT-qPCR. siRNA, wild-type and mutant Parkin plasmids were transfected using Amaxa system. Apoptosis was determined by PI staining of chondrocytes and TUNEL assay.

RESULTS

IL-1β-stimulated OA chondrocytes showed high levels of ROS generation, mitochondrial membrane damage, accumulation of damaged mitochondria and higher incidence of apoptosis. IL-1β stimulation of chondrocytes with depleted Parkin expression resulted in sustained high levels of ROS, accumulation of damaged/dysfunctional mitochondria and enhanced apoptosis. Parkin translocation to depolarized/damaged mitochondria and recruitment of p62/SQSTM1 was required for the elimination of damaged/dysfunctional mitochondria in IL-1β-stimulated OA chondrocytes. Importantly we demonstrate that Parkin elimination of depolarized/damaged mitochondria required the Parkin ubiquitin ligase activity and resulted in reduced ROS levels and inhibition of apoptosis in OA chondrocytes under pathological conditions.

CONCLUSIONS

Our data demonstrates that Parkin functions to eliminate depolarized/damaged mitochondria in chondrocytes which is necessary for mitochondrial quality control, regulation of ROS levels and chondrocyte survival under pathological conditions.

Oxidative Stress in Parkinson's Disease: A Systematic Review and Meta-Analysis

Oxidative stress has been suggested to play a key role in Parkinson's disease, but inconsistent results were found in clinical studies. This study sought to quantitatively summarize the blood and cerebrospinal fluid (CSF) oxidative stress marker data in PD patients. We performed a systematic search of PubMed and Web of Science, and studies were included if they provided data on peripheral blood and CSF oxidative stress marker concentrations in PD patients and healthy control (HC) subjects. Data were extracted by three independent investigators from 80 included studies encompassing 7,212 PD patients and 6,037 HC subjects. Of the 22 oxidative stress markers analyzed, random effects meta-analysis showed that blood concentrations of 8-OhdG, MDA, nitrite, and ferritin were increased in patients with PD compared with HC subjects. In contrast, we showed that blood levels of catalase, uric acid, glutathione, and total-cholesterol were significantly down-regulated in patients with PD when compared with controls. There were no significant differences between PD patients and HC subjects for blood, Mn, Cu, Zn, Fe, SOD, albumin, glutathione peroxidase, vitamin E, ceruloplasmin, triglycerides, lactoferrin, transferrin, LDL-cholesterol, and HDL-cholesterol. Due to the limited number of CSF studies with small sample size, this meta-analysis only showed non-significant association between CSF 8-OhdG and PD. The findings of our meta-analysis demonstrated higher blood concentrations of 8-OhdG, MDA, nitrite and ferritin, and lower blood concentrations of catalase, uric acid, glutathione and total-cholesterol in PD patients, strengthening the clinical evidence that PD is accompanied by increased oxidative stress.

Inhibition of the hepatic Nlrp3 protects dopaminergic neurons via attenuating systemic inflammation in a MPTP/p mouse model of Parkinson's disease

Background

Parkinson’s disease (PD) is a neurodegenerative disorder with progressive loss of dopaminergic (DA) neurons. Systemic inflammation is shown to initiate and exacerbate DA neuronal degeneration in the substantia nigra. The infiltration and transformation of immune cells from the peripheral tissues are detected in and around the affected brain regions of PD patients. Our previous studies demonstrated the crucial role that microglial Nod-like receptor protein (NLRP) 3 inflammasome plays in the pathogenesis of PD. Nevertheless, the direct linkage between peripheral inflammation and DA neuron death remains obscure.

Methods

In the present study, we detected the NLRP3 expressions in the midbrain, liver, and bone marrow-derived macrophages in response to 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) acute and chronic challenge. We then used a tail vein injection of Nlrp3-siRNA wrapped with lentivirus to explore the potential influence of hepatic NLRP3 inflammasome-mediated inflammation on neuronal injury in a mouse model of PD via immunohistochemistry, ELISA, and Western blotting analysis.

Results

We showed that siNlrp3 downregulated the NLRP3 protein expression and inhibited the activation of NLRP3 inflammasomes in mice livers. The tail vein injection of LV3-siNlrp3 reduced the liver pro-inflammatory cytokine production, which subsequently alleviated MPTP-triggered microglial activation and DA neuron loss in the midbrain. These findings indicated that inhibition of hepatic NLRP3 inflammasome weakens inflammatory cytokines spreading into the brain and delays the progress of neuroinflammation and DA neuronal degeneration.

Conclusion

This study gives us an insight into the direct linkage between liver inflammation and DA neuron damage in the pathogenesis of PD and provides the potential target of NLRP3 for developing novel drugs for PD therapy.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1236-z) contains supplementary material, which is available to authorized users.

Anti-Parkinson Potential of Silymarin: Mechanistic Insight and Therapeutic Standing

Parkinson’s disease (PD) involves aggregation of α-synuclein and progressive loss of dopaminergic neurons. Pathogenesis of PD may also be related to one’s genetic background. PD is most common among geriatric population and approximately 1–2% of population suffers over age 65 years. Currently no successful therapies are in practice for the management of PD and available therapies tend to decrease the symptoms of PD only. Furthermore, these are associated with diverse range of adverse effects profile. The neuroprotective effects of polyphenols are widely studied and documented. Among phytochemicals, silymarin is one of the most widely used flavonoids because of its extensive therapeutic properties and has been indicated in pathological conditions of prostate, CNS, lungs, skin, liver, and pancreas. Silymarin is a mixture of flavonolignans (silybin, isosilybin, and silychristin), small amount of flavonoids (taxifolin), fatty acids, and other polyphenolic compounds extracted from the dried fruit of Silybum marianum and is clinically used for hepatoprotective effects since ancient times. Neuroprotective effects of silymarin have been studied in various models of neurological disorders such as Alzheimer’s disease, PD, and cerebral ischemia. The aim of the present study is to provide a comprehensive review of the recent literature exploring the effects of silymarin administration on the progression of PD. Reducing oxidative stress, inflammatory cytokines, altering cellular apoptosis machinery, and estrogen receptor machinery are mechanisms that are responsible for neuroprotection by silymarin, as discussed in this review. Additionally, because of poor aqueous solubility, the bioavailability of silymarin is low and only 23–47% of silymarin reaches systemic circulation after oral administration. Our primary focus is on the chemical basis of the pharmacology of silymarin in the treatment of PD and its mechanisms and possible therapeutic/clinical status while addressing the bioavailability limitation.

An Inflammation-Centric View of Neurological Disease: Beyond the Neuron

Inflammation is a complex biological response fundamental to how the body deals with injury and infection to eliminate the initial cause of cell injury and effect repair. Unlike a normally beneficial acute inflammatory response, chronic inflammation can lead to tissue damage and ultimately its destruction, and often results from an inappropriate immune response. Inflammation in the nervous system (“neuroinflammation”), especially when prolonged, can be particularly injurious. While inflammation per se may not cause disease, it contributes importantly to disease pathogenesis across both the peripheral (neuropathic pain, fibromyalgia) and central [e.g., Alzheimer disease, Parkinson disease, multiple sclerosis, motor neuron disease, ischemia and traumatic brain injury, depression, and autism spectrum disorder] nervous systems. The existence of extensive lines of communication between the nervous system and immune system represents a fundamental principle underlying neuroinflammation. Immune cell-derived inflammatory molecules are critical for regulation of host responses to inflammation. Although these mediators can originate from various non-neuronal cells, important sources in the above neuropathologies appear to be microglia and mast cells, together with astrocytes and possibly also oligodendrocytes. Understanding neuroinflammation also requires an appreciation that non-neuronal cell—cell interactions, between both glia and mast cells and glia themselves, are an integral part of the inflammation process. Within this context the mast cell occupies a key niche in orchestrating the inflammatory process, from initiation to prolongation. This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia-glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuroinflammation.

White Matter Changes Correlates of Peripheral Neuroinflammation in Patients with Parkinson's Disease

Neuroinflammatory pathology has long been identified to contribute to the pathology of Parkinson disease. Early microstructural changes in white matter tracts might give a clue for earlier detection of PD. We investigated through diffusion MRI connectometry the structural correlates of white matter tracts of 81 patients with PD with whole blood neutrophil-to-lymphocyte ratio (NLR), controlling for age and sex. Diffusion data were reconstructed in the MNI space using q-space diffeomorphic reconstruction to obtain the spin distribution function. The spin distribution function (SDF) values were used in DMRI connectometry analysis. The connectometry analyses identified white matter QA of the following fibers to be correlated with NLR score after adjustment for age and sex: bilateral cingulum, body and left crus of fornix, bilateral corticospinal tract (CST), and body and splenium of corpus callosum (CC) and superior cerebellar peduncle with decreased connectivity related to NLR (FDR = 0.04542). Keeping with emerging evidence on the role of neuroinflammation in PD pathology, these results with functional relevance to prodromal Parkinson disease, bring new insights to pivotal role of peripheral inflammation in CNS neurodegeneration.

Juglanin ameliorates LPS-induced neuroinflammation in animal models of Parkinson's disease and cell culture via inactivating TLR4/NF-κB pathway

Parkinson's disease (PD) is a common neuro-degenerative disorder, and novel therapeutic targets are required for the treatment of PD. Juglanin is a natural compound extracted from the crude Polygonum aviculare, exhibiting anti-inflammatory, anti-oxidant and anti-cancer activities. In our study, PD in mice was induced by systemic LPS treatment as evidenced by enhanced α-synuclein and reduced tyrosine hydroxylase (TH), which were reversed by juglanin treatment. Moreover, juglanin administration attenuated LPS-caused behavioral and memory impairments and reduced LPS-induced enhancement of neuro-degenerative markers, including amyloid β (Aβ) and p-Tau. Additionally, juglanin ameliorated synaptic functionality through promoting the expression of synaptic markers, such as SYP, PSD-95 and SNAP-25. Toll-like receptor 4 (TLR4) signaling in brain regulates neuroinflammation, contributing to neurodegenerative diseases. Furthermore, LPS induced neuroinflammation through the acceleration of various pro-inflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-18 (IL-18) and Cyclooxygenase-2 (COX-2), via activating TLR4/nuclear factor (NF)-κB pathway in hippocampus of mice and microglia cells. Juglanin significantly reduced LPS-induced production of pro-inflammatory cytokines and blocked TLR4/NF-κB pathway. We also found that LPS-induced astrocytes (AST) activity was prevented by juglanin through down-regulating glial fibrillary acidic protein (GFAP) and Iba1 in vivo and in vitro. Together, our results indicated that juglanin ameliorated neuroinflammation-related memory impairment, and neurodegeneration through impeding TLR4/NF-κB, indicating its potential for PD prevention.

Brainstem cytokine changes in healthy ageing and Motor Neurone Disease

Neuroinflammation is linked to healthy ageing, but its role in the development of age-related neurodegenerative diseases is unclear. In this pilot study we used a multiplex assay approach to compare 27 cytokines in 6 young adult and 6 ageing control brainstems with those in 6 MND brainstems. We report that healthy ageing is associated with significantly increased brainstem levels of IL-1β, IP-10 and MIP-1β which co-localise immunocytochemically to astrocytes. MND brainstem is also characterised by a general increase in both pro- and anti-cytokine levels, but fails to show the expected age-related increase in MIP-1β and IP-10. This pilot study is the first to show that MND is associated with a failure of specific features of the normal age-related neuroinflammatory process. We suggest that our pilot data indicates that neuroinflammation during healthy ageing may not always be detrimental to motoneuronal survival and that age-related neurodegenerative diseases, such as MND, may instead result from defective neuroinflammation.