PhD Student, The University of Adelaide
Age-related increases in inflammatory status, as measured by elevated levels of pro-inflammatory cytokines, have been implicated in the development of age-related neurodegenerative diseases including Motor Neurone Disease (MND). However, recent studies in rats have revealed that elevated inflammation associated with healthy ageing may promote motoneuronal survival. Cytokine changes with healthy ageing have tended to be ignored in MND as most studies only compare MND tissue with age-matched controls. Objectives of my research were, 1) To characterise age-related changes in human brainstem cytokine levels, and 2) To determine whether ageing and MND brainstem are characterised by different brainstem cytokine profiles. 3) To determine the neuroglial cell types that express inflammatory cytokines. 27 cytokines (IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, IL-17A, TNF-α, IFN-ϒ, FGF, G-CSF, GM-CSF, IFN-ϒ, MCP-1, MIP-1α, MIP-1β, Eotaxin, PDGF-1β, RANTES and VEGF) were analysed using multiplex technology in fresh frozen post-mortem brainstems of MND patients aged 60-68 years (n=6), and compared with those of ageing controls aged 48-86 years (n=6) and young adult controls aged 20-33 years (n=6). Immunocytochemistry was used to colocalise selected cytokines to neuroglia. Levels of IL-1β and IP-10 were higher in brainstems of ageing controls compared to young adult controls (p=0.017 and p=0.020 respectively). Moreover, MIP-1β levels were higher in brainstems of ageing controls compared to young adult control brainstems (p=0.006) and decreased in MND brainstems compared to that of ageing controls (p=0.023). Immunocytochemistry showed that astrocytes were the source of MIP-1β. There is evidence from animal studies that MIP-1β is neuroprotective. The increased levels of MIP-1β with normal ageing found here may therefore be neuroprotective, whereas lower levels in MND may be associated with age-related motor neuronal degeneration.
Abstract: More and more data show isoflurane, a commonly used volatile anesthetic has dual effects on neuron fate. However, the underlying mechanisms that can explain the apparent paradox are poorly understood. Hypoxia inducible factor (HIF)-1α, a transcription factor, has been found regulating both prosurvival and prodeath pathways in the CNS. Previously, we found that isoflurane can activate HIF-1α under normoxic conditions in vitro and HIF-1α has been found to be involved in the pre-conditioning effect of isoflurane in various organs. Here, we investigated whether HIF-1α is a contributing factor in the neurodegenration in rodent primary cultured neurons and in developing rat brain. Isoflurane dose-dependently induced apoptotic neurodegeneration in neonatal rats as assessed by S100β, cleaved caspase 3 and poly-(ADP-ribose) polymerase (PARP), respectively. Notably, isoflurane up-regulates HIF-1α protein levels in vivo and in vitro during induction of neurodegeneration. Likewise, isoflurane resulted in a significant elevation of cytosonic calcium levels in neuron cultures. Furthermore, knockdown of HIF-1α expression in cultured neurons attenuated isoflurane-induced neurotoxicity. Finally, Morris water maze (MWM) test showed neonatal exposure to isoflurane impaired juvenile learning and memory ability in rats. These findings indicate that HIF-1α is involved in the neurodegeneration induced by isoflurane in the brain of neonatal rats, suggesting HIF-1α may be a candidate for the dual effects of isoflurane on neuron fate.
Pub.: 22 Nov '11, Pinned: 31 Jul '17
Abstract: Since accumulating evidence suggests the application of anesthetics may increase the risk of Alzheimer's disease (AD), we investigated the cytotoxicity of inhaled general anesthesia in neurons and its underlying mechanism. Using primary cultured rat hippocampal neurons as the study model, here we show that isoflurane increases vulnerability to intracellular or extracellular amyloid β with or without serum deprivation. This isoflurane-induced effect is mediated by the downregulation of miR-214 level that lead to an elevated expression of Bax, a prominent target for miR-214. We conclude that isoflurane increases cell death in the presence of amyloid β by increasing Bax level through downregulating miR-214. Our data provide a new insight for inhaled anesthetics toxicity and indicate a possible mechanistic link between anesthetic application and neurodegenration in AD.
Pub.: 15 Feb '13, Pinned: 31 Jul '17
Abstract: Rotenone, a commonly used pesticide, is well documented to induce selective degeneration in dopaminergic neurons and motor dysfunction. Such rotenone-induced neurodegenration has been primarily suggested through mitochondria-mediated apoptosis and reactive oxygen species (ROS) generation. But the status of rotenone induced changes in liver, the major metabolic site is poorly investigated. Thus, the present investigation was aimed to study the oxidative stress-induced cytotoxicity and apoptotic cell death in human liver cells-HepG2 receiving experimental exposure of rotenone (12.5-250 μM) for 24 h. Rotenone depicted a dose-dependent cytotoxic response in HepG2 cells. These cytotoxic responses were in concurrence with the markers associated with oxidative stress such as an increase in ROS generation and lipid peroxidation as well as a decrease in the glutathione, catalase, and superoxide dismutase levels. The decrease in mitochondrial membrane potential also confirms the impaired mitochondrial activity. The events of cytotoxicity and oxidative stress were found to be associated with up-regulation in the expressions (mRNA and protein) of pro-apoptotic markers viz., p53, Bax, and caspase-3, and down-regulation of anti-apoptotic marker Bcl-2. The data obtain in this study indicate that rotenone-induced cytotoxicity in HepG2 cells via ROS-induced oxidative stress and mitochondria-mediated apoptosis involving p53, Bax/Bcl-2, and caspase-3.
Pub.: 22 Aug '13, Pinned: 31 Jul '17
Abstract: Diabetes is associated with neurodegeneration. Glycation ensues in diabetes and glycated proteins cause insulin resistance in brain resulting in amyloid plaques and NFTs. Also glycation enhances gliosis by promoting neuroinflammation. Currently there is no therapy available to target neurodegenration in brain therefore, development of new therapy that offers neuroprotection is critical. The objective of this study was to evaluate mechanistic effect of isatin derivative URM-II-81, an anti-glycation agent for improvement of insulin action in brain and inhibition of neurodegenration. Methylglyoxal induced stress was inhibited by treatment with URM-II-81. Also, Ser473 and Ser9 phosphorylation of Akt and GSK-3β respectively were restored by URM-II-81. Effect of URM-II-81 on axonal integrity was studied by differentiating Neuro2A using retinoic acid. URM-II-81 restored axonal length in MGO treated cells. Its effects were also studied in high fat and low dose streptozotocin induced diabetic mice where it reduced RBG levels and inhibited glycative stress by reducing HbA1c. URM-II-81 treatment also showed inhibition of gliosis in hippocampus. Histological analysis showed reduced NFTs in CA3 hippocampal region and restoration of insulin signaling in hippocampii of diabetic mice. Our findings suggest that URM-II-81 can be developed as a new therapeutic agent for treatment of neurodegenration.
Pub.: 18 Jan '17, Pinned: 31 Jul '17
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