1. The role of Transition Metals & Reactive Oxygen Species (ROS) in Alzheimers Disease(AD). By Piril Erel UoB: 12004723 Piril Erel - UoB: 12004723 1 Normal Alzheimers

2. Content Pages: Piril Erel - UoB: 12004723 2 10.Production Of ROS Induced By A 11.Chelating Properties 12.PBT2 detoxifies A Plaques 13.The Healthy Synapse a glance into the synaptic cleft 14.Alzheimers Disease a glance into the synaptic cleft 15.PBT2 a glance into the synaptic cleft 16.Trial Method For PBT2 17.Results From PBT2 18.Conclusion 19.Ending 20.References 1. Aims & Objective 2. What Is Alzheimers Disease? 3. Risk Factors Associated With AD 4. Metal Homeostasis In Alzheimers Disease 5. Pathophysiology of AD 6. The Role Of Transition Metals 7. Amyloid- (A) Protein Plaque Formation And How It Links To Transition Metals 8. Aggregation Of A Is Metal Dependent 9. Interactions Of Transition Metals With Amyloid Protein (APP) 3. The main aim of this project is to investigate current research in Alzheimers Disease(AD) including novel ways to treat this illness which currently does not have any known cure. By doing this assignment I will introduce The Metal Hypothesis for AD and a novel drug called PBT2 which I will discuss in detail. Objectives: Explain The Metal Hypothesis Provide an insight in the dysfunctions of an AD-brain relating to the Metal Hypothesis Describe Reduced Oxygen Species (ROS) Discuss how the Metal Hypothesis integrates with ROS to cause AD Detail of how PBT2 could be an effective drug for AD patients. Aims & Objective Piril Erel - UoB: 12004723 3 4. Alzheimers Disease(AD) is a slow progressive and fatal neurodegenerative disease which is indicated by memory and cognitive dysfunction. Despite increasing knowledge of genetics, epidemiology and neuropathology AD is not treatable. Currently, disease modifying drugs or existing therapies only offer short-term symptomatic relief. It affects 800,000 people in the UK alone and 36 million people world wide, (data from 2010), this number approximately doubles every 20 years, and is estimated to reach 66 million in 2030 and 115 million in 2050.[1] This pressures scientists to make finding a long term pharmacotherapy a priority. What Is Alzheimers Disease? Piril Erel - UoB: 12004723 4 5. Risk Factors: 1. Age: a. 1/5 people over 65 will get Alzheimers Disease b. Up to 50% over age 85 have AD 2. Family History: a. Strong genetic component in most cases of AD 3. Other: a. Gender (female; menopause?) b. Stroke, Obesity, High Cholesterol c. Diabetes Piril Erel - UoB: 12004723 5 Risk Factors Associated With AD 6. The brain is a specialized organ which uses key cellular processes to work efficiently, these processes require a high concentration of transition metal ions such as zinc(Zn) and copper(Cu). Zn2+ & Cu2+ are required in neuronal activity within synapses Due to the necessity of these metal ions, cells have a sophisticated system to maintain metal-ion homeostasis. Breakdown of these mechanisms alter the ionic balance and can result in a disease state such as AD. These metal ions are suggested to have two distinct roles in the pathophysiology of AD: 1. Aggregation of A peptide plaques 2. Production of reactive oxygen species induced by A. Metal Homeostasis In Alzheimers Disease Piril Erel - UoB: 12004723 6 7. Promotion of A in the brain, which is collected over decades due to the presence of raised Zn2+ & Cu2+ concentrations. Sequestration of copper by A, drives the generation of reactive oxygen species. Excessive aggregates of A trap essential metals: Zinc & Copper. Piril Erel - UoB: 12004723 7 Pathophysiology Of AD 8. Metals are involved in essential biological functions but the transport and utilization are generally controlled by their chemistry making them physiologically useful and potentially able to give rise to pathological miracles. The levels of transition metals such as Cu, Fe and Zn in a healthy brain neocortical parenchyma are still maintained at a high concentration, however within an AD-affected brain these concentrations are increased with the highest levels found within amyloid plaque deposits[2]. Kenche et al stated that both the Zn2+ released from the presynaptic terminals and Cu2+ released from the post-synaptic terminals, following synapse stimulation, are pre-dominantly in a free exchangeable form. These ions, along with A in the synaptic cleft results in an inevitable interaction. The Role Of Transition Metals Pic Reference: Henryk Kozlowski, Marek Luczkowski, Maurizio Remelli, Daniel Valensin. (2012). Copper, Zinc and iron in neurodegenerative diseases (Alzheimer's, Parkinsons's and prion diseases). Metal Ion in Neurodegenerative Diseases. 256 (Fig. 3.), p1. Piril Erel - UoB: 12004723 8 9. A is the main component of deposits found in the regions of the brain involved with memory, emotions and intellectual function of patients with AD[3]. Cherny et al, 1999 found that the use of promoting chelation of metals in postmortem studies have shown that Zn2+ and Cu2+ mediate the precipitation of A deposits in AD-brain tissue. Studies show that the neuropil and amyloid plaques in AD-brains have a high concentration of Cu and Zn, however we do not know whether this is due to: Abnormal activity of Cu (or Zn) homeostasis which initiates Amyloid- plaques. Amyloid plaques having a high affinity to metal ions. Amyloid plaques acting as metal sinks absorbing the ions into their core [4]. Amyloid- (A) Protein Plaque Formation And How It Links To Transition Metals Pic2 - Reference: AHAF (American Health Assistance Foundation). (). Amyloid Plaques and Neurofibrillary Tangles.. Available: http://pakmed.net/academic/age/alz/alz030.htm. Last accessed 14th Apr 2013. Piril Erel - UoB: 12004723 9 10. + Zn2+/Cu2+ A Monomer Oligomer Protofibril - Amyloid Fibril Aggregation Of A Is Metal Dependent Non- Pathogenic Synaptic Dysfunction Membrane Disruption Inflammation Subsequently research showed that Zn2+ & Cu2+ are required for the aggregation of A. Piril Erel - UoB: 12004723 10 11. A Copper binding forms oxidative crosslinks between monomers. The resulting cross-linked species are called oligomers. Oligomers are very difficult for the brain to clear and can eventually cause neuron death Craddock et al, 2012 observed metal dyshomeostasis in a AD-affected mouse model. The interaction between A and metals therefore represents a mechanism of therapeutic intervention that could both normalize metal homeostasis and reduce the levels of toxic A oligomers in the brain. *5+ Furthermore, Copper binding to A also generates ROS, this binding causes a detrimental release of ROS. Piril Erel - UoB: 12004723 11 Interactions Of Transition Metals With Amyloid - Protein (APP) 12. The brain needs oxygen in order to synthesize the large quantities of ATP required. This accounts for 20% of the bodys total basal oxygen consumption therefore generates high levels of reactive oxygen species (ROS). Exposure to ROS damages neurons in the brain. Oxidative stress plays an important role in initiating AD through provoking cell signaling pathways. [4] It represents an imbalance between the amount of ROS being produced and the ability of the body to detect and remove these toxic substances. This is due to cellular antioxidant defense mechanisms becoming overwhelmed by ROS causing macromolecular damage. ROS may also result in harmful effects such as; Damage of DNA. Oxidation of polyunsaturated fatty acids. Oxidation of amino acids in proteins. Oxidatively inactivation of specific enzymes. [6] Production Of Reactive Oxygen Species Induced By A Piril Erel - UoB: 12004723 12 13. In order for a drug to be used as a potential treatment for brain disorders, it must possess certain characteristics which enable it to pass the blood brain barrier(BBB) such as: Low molecular weight Poorly charged or not charged at all Stable Selectivity of certain metal ions Low toxicity Minimum side effects.[7] Chelating Properties Piril Erel - UoB: 12004723 13 14. This recently discovered treatment shows rapid improvement in cognition in mouse models of AD. A Copper/Zinc Ionophore it competes for metals but also redistributes metals back into the cell as it transports ions across the lipid bilayer. PBT2 aids the clearance of A aggregates in the brain by targeting zinc and copper ions effectively it detoxifies the A plaques. PBT2 has a greater affinity for metal compared to As affinity to metal: A affinity for Zn is - Kd = 10-9 PBT2 affinity for Zn is - Kd =10-13 Metals are promiscuous, they can jump and bind to which ever is stronger, so if a metal is bound to an A plaque and PBT2 is present, due to the 104x greater force, the metal will dissociate and bind to the drug. PBT2 provides a mechanism which shuttles metals away from A PBT2 detoxifies A plaques Piril Erel - UoB: 12004723 14 15. Zn2+ is exocytosed into the synaptic cleft in concentrations of around 300 M Cu2+ is released post-synaptically following activation of NMDA with Cu2+ concentrations around 15 M in the synaptic cleft. Once cleavage of APP takes place, A is released into the synaptic cleft and it aids lowering of zinc concentration by acting as a sponge. A is further degraded by enzymes into smaller monomers.[8] The Healthy Synapse a glance into the synaptic cleft Piril Erel - UoB: 12004723 15 16. The decrease in ATP leads to a reduction metal reuptake, causing the average concentration of metals to rise over time. Cu & Zn react with A forming A oligomers and then, crucially, to A amyloid plaques A can bind up to 2.5 moles of metal ions however the more metals it is bound to, the more aggregated it becomes A oligomers are resistant to degradation. Alzheimers Disease a glance into the synaptic cleft Piril Erel - UoB: 12004723 16 17. PBT2: PBT2 taken orally crosses the blood brain barrier and can be detected in the synaptic cleft. PBT2 has a high affinity for metals Chelation by PBT2 allows Zu & Cu to be removed from A The advantage of PBT2 lies in the ionophoric properties of the drug Concentrations of the metal ions are reduced to normal Thus diverted from binding to A, This reduces precipitation, reduces covalent A oligomer formation and reduces toxic redox activity. PBT2 a glance into the synaptic cleft Piril Erel - UoB: 12004723 17 18. Objectives For Phase IIa: To test the safety and efficacy of PBT2 in patients with mild AD. To monitor any changes in cognition after administration of PBT2 using the Neuro-psychological Test Battery (NTB) which measures Executive Function(EF). PBT2 has undergone a 12 week Phase II trial in which the drug was orally administered daily to 78 patients with mild AD who where randomly allocated into either one of the 3 groups below: Placebo 50mg and 250mg It was a double-blind, randomized, placebo-controlled trial Trial Method For PBT2 Piril Erel - UoB: 12004723 18 19. Patients with a 250mg dose of PBT2 daily showed a significant increase in EF scores compared to the placebo group. 250mg dose of PBT2 also showed a significant decrease in A protein plaques.*9+ This shows promising results for PBT2 as a treatment drug for Alzheimers Disease. Phase IIb clinical trials is currently underway this time scientists are evaluating the effect of PBT2 on: Safety and tolerability Brain metabolic activity Brain volumes Cognition Functional abilities[10] Results Piril Erel - UoB: 12004723 19 20. Through thorough research into this area, current drug trials target memory deficit in early moderate Alzheimers However it is questionable whether this is too late. Consideration of executive function and early treatment of AD; a cure may be possible or at least consequences are more reversible. PBT2 not only detoxifies the harmful A plaques but also re-establishes homeostasis of metals at a stage where neuronal death hasnt yet occurred. Clinical trials for PBT2 Phase IIb will hopefully provide promising results for curing AD. Conclusion Piril Erel - UoB: 12004723 20 21. Thank You For Listening & Watching, Piril Erel 12004723 Piril Erel - UoB: 12004723 21 22. 1. Nicole L Batsch, Mary S Mittelman. (2012). Overcoming The Stigma Of Dementia. Available: www.alz.co.uk/research/WorldAlzheimerReport2012.pdf. Last accessed 2th Apr 2013. 2. Craig S. Atwood, Richard C. Scarpa, Xudong Huang, Robert D. Moir, Walton D. Jones, David P. Fairlie, Rudolph E. Tanzi and Ashley I. Bush.. (2000). Characterization of Copper Interactions with Alzheimer Amyloid Beta Peptides: Identification of an Attomolar-Affinity Copper Binding Site on Amyloid Beta142. Journal of Neurochemistry. 75 (No.3), 1219. 3. Martini, FH (2012). Fundamentals of Anatomy & Physiology. 9th ed. San Francisco: Pearson Education. 542. 4. Xiongwei Zhu, Bo Su, Xinglong Wang, Akihiko Nunomura, Paula I. Moreira, Hyoung-gon Lee, George Perry, Mark A. Smith, . (2008). Oxidative Stress Signaling in Alzheimer's Disease. National Institute of Health. 5(6) (1), 525-532. 5. Daniel Kantor. (October 4, 2010). Alzheimer's Disease. Available: www.scripps.org/articles/3458-alzheimer-s-disease. Last accessed 15th Apr 2013. 6. Brooker, Robert J. (2011). Genetics: analysis and principles (4th ed.). McGraw-Hill Science. 7. Budimir, A. Metal Ions, Alzheimers Disease & Chelation Therapy. Acta Pharm.2011;61():1-14 8. Duce, JA et al. (2010). Biological Metals & Alzheimer's Disease: Implications for therapeutics and diagnostics. Progress in Neurobiology. 92 (1-18), 4. 9. Faux, N.A et al. (2010). PBT2 Rapidly Improves Cognition in Alzheimer's Disease: Additional Phase II Analyses. Journal of Alzheimer's Disease. 20 (1), 509-516. 10. Lannfelt, L and Prana Biotechnology. (2013). PBT2 Clinical Program. Available: www.pranabio.com/default.asp?contentID=625. Last accessed 20th Apr 2013. Piril Erel - UoB: 12004723 22 References