Alzheimer
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A New Therapeutic Drug for Alzheimer’s Disease without Inflammatory Side Effects
Although Aduhelm, a monoclonal antibody targeting amyloid beta (Aβ), recently became the first US FDA approved drug for Alzheimer’s disease (AD) based on its ability to decrease Aβ plaque burden in AD patients, its effect on cognitive improvement is still controversial. Moreover, about 40% of the patients treated with this antibody experienced serious side effects including cerebral edemas (ARIA-E) and hemorrhages (ARIA-H) that are likely related to inflammatory responses in the brain when the Aβ antibody binds Fc receptors (FCR) of immune cells such as microglia and macrophages.
These inflammatory side effects can cause neuronal cell death and synapse elimination by activated microglia, and even have the potential to exacerbate cognitive impairment in AD patients. Thus, current Aβ antibody-based immunotherapy holds the inherent risk of doing more harm than good due to their inflammatory side effects.
To overcome these problems, a team of researchers at KAIST in South Korea has developed a novel fusion protein drug, αAβ-Gas6, which efficiently eliminates Aβ via an entirely different mechanism than Aβ antibody-based immunotherapy. In a mouse model of AD, αAβ-Gas6 not only removed Aβ with higher potency, but also circumvented the neurotoxic inflammatory side effects associated with conventional antibody treatments.
Their findings were published on August 4 in Nature Medicine.
Schematic of a chimeric Gas6 fusion protein. A single chain variable fragment (scFv) of
an Amyloid β (Aβ)-targeting monoclonal antibody is fused with a truncated receptor binding
domain of Gas6, a bridging molecule for the clearance of dead cells via TAM (TYRO3, AXL,
and MERTK) receptors, which are expressed by microglia and astrocytes.
“FcR activation by Aβ targeting antibodies induces microglia-mediated Aβ phagocytosis, but it also produces inflammatory signals, inevitably damaging brain tissues,” said paper authors Chan Hyuk Kim and Won-Suk Chung, associate professors in the Department of Biological Sciences at KAIST.
“Therefore, we utilized efferocytosis, a cellular process by which dead cells are removed by phagocytes as an alternative pathway for the clearance of Aβ in the brain,” Prof. Kim and Chung said. “Efferocytosis is accompanied by anti-inflammatory responses to maintain tissue homeostasis. To exploit this process, we engineered Gas6, a soluble adaptor protein that mediates efferocytosis via TAM phagocytic receptors in such a way that its target specificity was redirected from dead cells to Aβ plaques.”
The professors and their team demonstrated that the resulting αAβ-Gas6 induced Aβ engulfment by activating not only microglial but also astrocytic phagocytosis since TAM phagocytic receptors are highly expressed by these two major phagocytes in the brain. Importantly, αAβ-Gas6 promoted the robust uptake of Aβ without showing any signs of inflammation and neurotoxicity, which contrasts sharply with the treatment using an Aβ monoclonal antibody. Moreover, they showed that αAβ-Gas6 substantially reduced excessive synapse elimination by microglia, consequently leading to better behavioral rescues in AD model mice.
“By using a mouse model of cerebral amyloid angiopathy (CAA), a cerebrovascular disorder caused by the deposition of Aβ within the walls of the brain’s blood vessels, we also showed that the intrathecal administration of Gas6 fusion protein significantly eliminated cerebrovascular amyloids, along with a reduction of microhemorrhages. These data demonstrate that aAb-Gas6 is a potent therapeutic agent in eliminating Aβ without exacerbating CAA-related microhemorrhages.”
The resulting αAβ-Gas6 clears Aβ oligomers and fibrils without causing neurotoxicity (a-b, neurons: red, and fragmented axons: yellow) and proinflammatory responses (c, TNF release), which are conversely exacerbated by the treatment of an Aβ-targeting monoclonal antibody (Aducanumab).
Professors Kim and Chung noted, “We believe our approach can be a breakthrough in treating AD without causing inflammatory side effects and synapse loss. Our approach holds promise as a novel therapeutic platform that is applicable to more than AD. By modifying the target-specificity of the fusion protein, the Gas6-fusion protein can be applied to various neurological disorders as well as autoimmune diseases affected by toxic molecules that should be removed without causing inflammatory responses.”
The number and total area of Aβ plaques (Thioflavin-T, green) were significantly reduced in αAβ-Gas6-treated AD mouse brains compared to Aducanumab-treated ones (a, b). The cognitive functions of AD model mice were significantly rescued by αAβ-Gas6 treatment, whereas Aducanumab-treated AD mice showed partial rescue in these cognitive tests (c-e).
Professors Kim and Chung founded “Illimis Therapeutics” based on this strategy of designing chimeric Gas6 fusion proteins that would remove toxic aggregates from the nervous system. Through this company, they are planning to further develop various Gas6-fusion proteins not only for Ab but also for Tau to treat AD symptoms.
This work was supported by KAIST and the Korea Health Technology R&D Project that was administered by the Korea Health Industry Development Institute (KHIDI) and the Korea Dementia Research Center (KDRC) funded by the Ministry of Health & Welfare (MOHW) and the Ministry of Science and ICT (MSIT), and KAIST.
Other contributors include Hyuncheol Jung and Se Young Lee, Sungjoon Lim, Hyeong Ryeol Choi, Yeseong Choi, Minjin Kim, Segi Kim, the Department of Biological Sciences, and the Korea Advanced Institute of Science and Technology (KAIST).
To receive more up-to-date information on this new development, follow “Illimis Therapeutics” on twitter @Illimistx.
2022.08.05 View 8988 -
KAIST Research Team Proves How a Neurotransmitter may be the Key in Controlling Alzheimer’s Toxicity
With nearly 50 million dementia patients worldwide, and Alzheimers’s disease is the most common neurodegenerative disease. Its main symptom is the impairment of general cognitive abilities, including the ability to speak or to remember. The importance of finding a cure is widely understood with increasingly aging population and the life expectancy being ever-extended. However, even the cause of the grim disease is yet to be given a clear definition.
A KAIST research team in the Department of Chemistry led by professor Mi Hee Lim took on a lead to discovered a new role for somatostatin, a protein-based neurotransmitter, in reducing the toxicity caused in the pathogenic mechanism taken towards development of Alzheimer’s disease. The study was published in the July issue of Nature Chemistry under the title, “Conformational and functional changes of the native neuropeptide somatostatin occur in the presence of copper and amyloid-β”.
According to the amyloid hypothesis, the abnormal deposition of Aβ proteins causes death of neuronal cells. While Aβ agglomerations make up most of the aged plaques through fibrosis, in recent studies, high concentrations of transitional metal were found in the plaques from Alzheimer’s patients.
This suggests a close interaction between metallic ions and Aβ, which accelerates the fibrosis of proteins. Copper in particular is a redox-activating transition metal that can produce large amounts of oxygen and cause serious oxidative stress on cell organelles. Aβ proteins and transition metals can closely interact with neurotransmitters at synapses, but the direct effects of such abnormalities on the structure and function of neurotransmitters are yet to be understood.
Figure 1. Functional shift of somatostatin (SST) by factors in the pathogenesis of Alzheimer's disease.
Figure 2. Somatostatin’s loss-of-function as neurotransmitter. a. Schematic diagram of SST auto-aggregation due to Alzheimer's pathological factors. b. SST’s aggregation by copper ions. c. Coordination-prediction structure and N-terminal folding of copper-SST. d. Inhibition of SST receptor binding specificity by metals.
In their research, Professor Lim’s team discovered that when somatostatin, the protein-based neurotransmitter, is met with copper, Aβ, and metal-Aβ complexes, self-aggregates and ceases to perform its innate function of transmitting neural signals, but begins to attenuate the toxicity and agglomeration of metal-Aβ complexes.
Figure 3. Gain-of-function of somatostatin (SST) in the dementia setting. a. Prediction of docking of SST and amyloid beta. b. SST making metal-amyloid beta aggregates into an amorphous form. c. Cytotoxic mitigation effect of SST. d. SST mitigating the interaction between amyloid beta protein with the cell membrane.
This research, by Dr. Jiyeon Han et al. from the KAIST Department of Chemistry, revealed the coordination structure between copper and somatostatin at a molecular level through which it suggested the agglomeration mechanism, and discovered the effects of somatostatin on Aβ agglomeration path depending on the presence or absence of metals. The team has further confirmed somatostatin’s receptor binding, interactions with cell membranes, and effects on cell toxicity for the first time to receive international attention.
Professor Mi Hee Lim said, “This research has great significance in having discovered a new role of neurotransmitters in the pathogenesis of Alzheimer’s disease.” “We expect this research to contribute to defining the pathogenic network of neurodegenerative diseases caused by aging, and to the development of future biomarkers and medicine,” she added.
This research was conducted jointly by Professor Seung-Hee Lee’s team of KAIST Department of Biological Sciences, Professor Kiyoung Park’s Team of KAIST Department of Chemistry, and Professor Yulong Li’s team of Peking University.
The research was funded by Basic Science Research Program of the National Research Foundation of Korea and KAIST.
For more information about the research team, visit the website: https://sites.google.com/site/miheelimlab/1-professor-mi-hee-lim.
2022.07.29 View 10346 -
Simple Molecular Reagents to Treat Alzheimer’s Disease
- Researchers report minimalistic principles for designing small molecules with multiple reactivities against dementia. -
Sometimes the most complex problems actually have very simple solutions. A group of South Korean researchers reported an efficient and effective redox-based strategy for incorporating multiple functions into simple molecular reagents against neurodegenerative disorders. The team developed redox-active aromatic molecular reagents with a simple structural composition that can simultaneously target and modulate various pathogenic factors in complex neurodegenerative disorders such as Alzheimer’s disease.
Alzheimer’s disease is one of the most prevalent neurodegenerative disorders, affecting one in ten people over the age of 65. Early-onset dementia also increasingly affects younger people.
A number of pathogenic elements such as reactive oxygen species, amyloid-beta, and metal ions have been suggested as potential causes of Alzheimer’s disease. Each element itself can lead to Alzheimer’s disease, but interactions between them may also aggravate the patient’s condition or interfere with the appropriate clinical care.
For example, when interacting with amyloid-beta, metal ions foster the aggregation and accumulation of amyloid-beta peptides that can induce oxidative stress and toxicity in the brain and lead to neurodegeneration.
Because these pathogenic factors of Alzheimer’s disease are intertwined, developing therapeutic agents that are capable of simultaneously regulating metal ion dyshomeostasis, amyloid-beta agglutination, and oxidative stress responses remains a key to halting the progression of the disease.
A research team led by Professor Mi Hee Lim from the Department of Chemistry at KAIST demonstrated the feasibility of structure-mechanism-based molecular design for controlling a molecule’s chemical reactivity toward the various pathological factors of Alzheimer’s disease by tuning the redox properties of the molecule.
This study, featured as the ‘ACS Editors’ Choice’ in the May 6th issue of the Journal of the American Chemical Society (JACS), was conducted in conjunction with KAIST Professor Mu-Hyun Baik’s group and Professor Joo-Young Lee’s group at the Asan Medical Center.
Professor Lim and her collaborators rationally designed and generated 10 compact aromatic molecules presenting a range of redox potentials by adjusting the electronic distribution of the phenyl, phenylene, or pyridyl moiety to impart redox-dependent reactivities against the multiple pathogenic factors in Alzheimer’s disease.
During the team’s biochemical and biophysical studies, these designed molecular reagents displayed redox-dependent reactivities against numerous desirable targets that are associated with Alzheimer’s disease such as free radicals, metal-free amyloid-beta, and metal-bound amyloid-beta.
Further mechanistic results revealed that the redox properties of these designed molecular reagents were essential for their function. The team demonstrated that these reagents engaged in oxidative reactions with metal-free and metal-bound amyloid-beta and led to chemical modifications. The products of such oxidative transformations were observed to form covalent adducts with amyloid-beta and alter its aggregation.
Moreover, the administration of the most promising candidate molecule significantly attenuated the amyloid pathology in the brains of Alzheimer’s disease transgenic mice and improved their cognitive defects.
Professor Lim said, “This strategy is straightforward, time-saving, and cost-effective, and its effect is significant. We are excited to help enable the advancement of new therapeutic agents for neurodegenerative disorders, which can improve the lives of so many patients.”
This work was supported by the National Research Foundation (NRF) of Korea, the Institute for Basic Science (IBS), and the Asan Institute for Life Sciences.
Image credit: Professor Mi Hee Lim, KAIST
Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of the news coverage of this paper only.
Publication:
Kim, M. et al. (2020) ‘Minimalistic Principles for Designing Small Molecules with Multiple Reactivities against Pathological Factors in Dementia.’ Journal of the American Chemical Society (JACS), Volume 142, Issue 18, pp.8183-8193. Available online at https://doi.org/10.1021/jacs.9b13100
Profile:
Mi Hee Lim
Professor
miheelim@kaist.ac.kr
http://sites.google.com/site/miheelimlab
Lim Laboratory
Department of Chemistry
KAIST
Profile:
Mu-Hyun Baik
Professor
mbaik2805@kaist.ac.kr
https://baik-laboratory.com/
Baik Laboratory
Department of Chemistry
KAIST
Profile:
Joo-Yong Lee
Professor
jlee@amc.seoul.kr
Asan Institute for Life Sciences
Asan Medical Center
(END)
2020.05.11 View 12714 -
A Study Finds Neuropeptide Somatostatin Enhances Visual Processing
Researchers have confirmed that neuropeptide somatostatin can improve cognitive function in the brain. A research group of Professor Seung-Hee Lee from the Department of Biological Sciences at KAIST found that the application of neuropeptide somatostatin improves visual processing and cognitive behaviors by reducing excitatory inputs to parvalbumin-positive interneurons in the cortex.
This study, reported at Science Advances on April 22nd (EST), sheds a new light on the therapeutics of neurodegenerative diseases. According to a recent study in Korea, one in ten seniors over 65 is experiencing dementia-related symptoms in their daily lives such like memory loss, cognitive decline, and motion function disorders. Professor Lee believes that somatostatin treatment can be directly applied to the recovery of cognitive functions in Alzheimer’s disease patients.
Professor Lee started this study noting the fact that the level of somatostatin expression was dramatically decreased in the cerebral cortex and cerebrospinal fluid of Alzheimer’s disease patients
Somatostatin-expressing neurons in the cortex are known to exert the dendritic inhibition of pyramidal neurons via GABAergic transmission. Previous studies focused on their inhibitory effects on cortical circuits, but somatostatin-expressing neurons can co-release somatostatin upon activation. Despite the abundant expression of somatostatin and its receptors in the cerebral cortex, it was not known if somatostatin could modulate cognitive processing in the cortex.
The research team demonstrated that the somatostatin treatment into the cerebral cortex could enhance visual processing and cognitive behaviors in mice. The research team combined behaviors, in vivo and in vitro electrophysiology, and electron microscopy techniques to reveal how the activation of somatostatin receptors in vivo enhanced the ability of visual recognition in animals. Interestingly, somatostatin release can reduce excitatory synaptic transmission to another subtype of GABAergic interneurons, parvalbumin (PV)-expressing neurons.
As somatostatin is a stable and safe neuropeptide expressed naturally in the mammalian brain, it was safe to be injected into the cortex and cerebrospinal fluid, showing a potential application to drug development for curing cognitive disorders in humans.
Professor Lee said, “Our research confirmed the key role of the neuropeptide SST in modulating cortical function and enhancing cognitive ability in the mammalian brain. I hope new drugs can be developed based on the function of somatostatin to treat cognitive disabilities in many patients suffering from neurological disorders.”
This study was supported by the National Research Foundation of Korea.
Publication:
Song, Y. H et al. (2020) ‘Somatostatin enhances visual processing and perception by suppressing excitatory inputs to parvalbumin-positive interneurons in V1’, Science Advances, 6(17). Available online at https://doi.org/10.1126/sciadv.aaz0517
Profile:
Seung-Hee Lee
Associate Professor
shlee1@kaist.ac.kr
https://sites.google.com/site/leelab2013/
Sensory Processing Lab (SPL)
Department of Biological Sciences (BIO)
Korea Advanced Institute of Science and Technology (KAIST)
Profile:
You-Hyang Song
Researcher (Ph.D.)
dbgidtm17@kaist.ac.kr
SPL, KAIST BIO
Profile:
Yang-Sun Hwang
Researcher (M.S.)
hys940129@kaist.ac.kr
SPL, KAIST BIO
(END)
2020.04.23 View 11366 -
Blood-Based Multiplexed Diagnostic Sensor Helps to Accurately Detect Alzheimer’s Disease
A research team at KAIST reported clinically accurate multiplexed electrical biosensor for detecting Alzheimer’s disease by measuring its core biomarkers using densely aligned carbon nanotubes.
Alzheimer’s disease is the most prevalent neurodegenerative disorder, affecting one in ten aged over 65 years. Early diagnosis can reduce the risk of suffering the disease by one-third, according to recent reports. However, its early diagnosis remains challenging due to the low accuracy but high cost of diagnosis.
Research team led by Professors Chan Beum Park and Steve Park described an ultrasensitive detection of multiple Alzheimer's disease core biomarker in human plasma. The team have designed the sensor array by employing a densely aligned single-walled carbon nanotube thin films as a transducer.
The representative biomarkers of Alzheimer's disease are beta-amyloid42, beta-amyloid40, total tau protein, phosphorylated tau protein and the concentrations of these biomarkers in human plasma are directly correlated with the pathology of Alzheimer’s disease.
The research team developed a highly sensitive resistive biosensor based on densely aligned carbon nanotubes fabricated by Langmuir-Blodgett method with a low manufacturing cost.
Aligned carbon nanotubes with high density minimizes the tube-to-tube junction resistance compared with randomly distributed carbon nanotubes, which leads to the improvement of sensor sensitivity. To be more specific, this resistive sensor with densely aligned carbon nanotubes exhibits a sensitivity over 100 times higher than that of conventional carbon nanotube-based biosensors.
By measuring the concentrations of four Alzheimer’s disease biomarkers simultaneously Alzheimer patients can be discriminated from health controls with an average sensitivity of 90.0%, a selectivity of 90.0% and an average accuracy of 88.6%.
This work, titled “Clinically accurate diagnosis of Alzheimer’s disease via multiplexed sensing of core biomarkers in human plasma”, were published in Nature Communications on January 8th 2020. The authors include PhD candidate Kayoung Kim and MS candidate Min-Ji Kim.
Professor Steve Park said, “This study was conducted on patients who are already confirmed with Alzheimer’s Disease. For further use in practical setting, it is necessary to test the patients with mild cognitive impairment.” He also emphasized that, “It is essential to establish a nationwide infrastructure, such as mild cognitive impairment cohort study and a dementia cohort study. This would enable the establishment of world-wide research network, and will help various private and public institutions.”
This research was supported by the Ministry of Science and ICT, Human Resource Bank of Chungnam National University Hospital and Chungbuk National University Hospital.
< A schematic diagram of a high-density aligned carbon nanotube-based resistive sensor that distinguishes patients with Alzheimer’s Disease by measuring the concentration of four biomarkers in the blood. >
Profile:
Professor Steve Park
stevepark@kaist.ac.kr
Department of Materials Science and Engineering
http://steveparklab.kaist.ac.kr/
KAIST
Profile:
Professor Chan Beum Park
parkcb at kaist.ac.kr
Department of Materials Science and Engineering
http://biomaterials.kaist.ac.kr/
KAIST
2020.02.07 View 8944 -
Newly Identified Meningeal Lymphatic Vessels Answers the Key Questions on Brain Clearance
(Figure: Schematic images of location and features of meningeal lymphatic vessels and their changes associated with ageing.)
Just see what happens when your neighborhood’s waste disposal system is out of service. Not only do the piles of trash stink but they can indeed hinder the area’s normal functioning. That is also the case when the brain’s waste management is on the blink.
The buildup of toxic proteins in the brain causes a massive damage to the nerves, leading to cognitive dysfunction and increased probability of developing neurodegenerative disorders such as Alzheimer's disease. Though the brain drains its waste via the cerebrospinal fluid (CSF), little has been understood about an accurate route for the brain’s cleansing mechanism.
Medical scientists led by Professor Gou Young Koh at the Graduate School of Medical Science and Engineering have reported the basal side of the skull as the major route, so called “hotspot” for CSF drainage.
They found that basal meningeal lymphatic vessels (mLVs) function as the main plumbing pipes for CSF. They confirmed macromolecules in the CSF mainly runs through the basal mLVs. Notably, the team also revealed that the brain’s major drainage system, specifically basal mLVs are impaired with aging. Their findings have been reported in the journal Nature on July 24.
Throughout our body, excess fluids and waste products are removed from tissues via lymphatic vessels. It was only recently discovered that the brain also has a lymphatic drainage system. mLVs are supposed to carry waste from the brain tissue fluid and the CSF down the deep cervical lymph nodes for disposal. Still scientist are left with one perplexing question — where is the main exit for the CSF? Though mLVs in the upper part of the skull (dorsal meningeal lymphatic vessels) were reported as the brain’s clearance pathways in 2014, no substantial drainage mechanism was observed in that section.
“As a hidden exit for CSF, we looked into the mLVs trapped within complex structures at the base of the skull,” says Dr. Ji Hoon Ahn, the first author of this study. The researchers used several techniques to characterize the basal mLVs in detail. They used a genetically engineered lymphatic-reporter mouse model to visualize mLVs under a fluorescence microscope. By performing a careful examination of the mice skull, they found distinctive features of basal mLVs that make them suitable for CSF uptake and drainage. Just like typical functional lymphatic vessels, basal mLVs are found to have abundant lymphatic vessel branches with finger-like protrusions. Additionally, valves inside the basal mLVs allow the flow to go in one direction. In particular, they found that the basal mLVs are closely located to the CSF. Dr. Hyunsoo Cho, the first author of this study explains, “All up, it seemed a solid case that basal mLVs are the brain’s main clearance pathways.
The researchers verified such specialized morphologic characteristics of basal mLVs indeed facilitate the CSF uptake and drainage. Using CSF contrast-enhanced magnetic resonance imaging in a rat model, they found that CSF is drained preferentially through the basal mLVs. They also utilized a lymphatic-reporter mouse model and discovered that fluorescence-tagged tracer injected into the brain itself or the CSF is cleared mainly through the basal mLVs. Jun-Hee Kim, the first author of this study notes, “We literally saw that the brain clearance mechanism utilizing basal outflow route to exit the skull.
It has long been suggested that CSF turnover and drainage declines with ageing. However, alteration of mLVs associated with ageing is poorly understood. In this study, the researchers observed changes of mLVs in young (3-month-old) and aged (24~27-months-old) mice. They found that the structure of the basal mLVs and their lymphatic valves in aged mice become severely flawed, thus hampering CSF clearance. The corresponding author of this study, Dr. Koh says, “By characterizing the precise route for fluids leaving the brain, this study improves our understanding on how waste is cleared from the brain. Our findings also provide further insights into the role of impaired CSF clearance in the development of age-related neurodegenerative diseases.”
Many current therapies for Alzheimer’s disease target abnormally accumulated proteins, such as beta-amyloid. By mapping out a precise route for the brain’s waste clearance system, this study may be able to help find ways to improve the brain’s cleansing function. Such breakthrough might become quite a sensational strategy for eliminating the buildup of aging-related toxic proteins. “It definitely warrants more extensive investigation of mLVs in patients with age-related neurodegenerative disease such as Alzheimer’s disease prior to clinical investigation,” adds Professor Koh.
2019.07.25 View 31050 -
Deciphering Brain Somatic Mutations Associated with Alzheimer's Disease
Researchers have found a potential link between non-inherited somatic mutations in the brain and the progression of Alzheimer’s disease
Researchers have identified somatic mutations in the brain that could contribute to the development of Alzheimer’s disease (AD). Their findings were published in the journal Nature Communications last week.
Decades worth of research has identified inherited mutations that lead to early-onset familial AD. Inherited mutations, however, are behind at most half the cases of late onset sporadic AD, in which there is no family history of the disease. But the genetic factors causing the other half of these sporadic cases have been unclear.
Professor Jeong Ho Lee at the Graduate School of Medical Science and Engineering and colleagues analysed the DNA present in post-mortem hippocampal formations and in blood samples from people aged 70 to 96 with AD and age-matched controls. They specifically looked for non-inherited somatic mutations in their brains using high-depth whole exome sequencing.
The team developed a bioinformatics pipeline that enabled them to detect low-level brain somatic single nucleotide variations (SNVs) – mutations that involve the substitution of a single nucleotide with another nucleotide. Brain somatic SNVs have been reported on and accumulate throughout our lives and can sometimes be associated with a range of neurological diseases.
The number of somatic SNVs did not differ between individuals with AD and non-demented controls. Interestingly, somatic SNVs in AD brains arise about 4.8 times more slowly than in blood. When the team performed gene-set enrichment tests, 26.9 percent of the AD brain samples had pathogenic brain somatic SNVs known to be linked to hyperphosphorylation of tau proteins, which is one of major hallmarks of AD.
Then, they pinpointed a pathogenic SNV in the PIN1 gene, a cis/trans isomerase that balances phosphorylation in tau proteins, found in one AD patient’s brain. They found the mutation was 4.9 time more abundant in AT8-positive – a marker for hyper-phosphorylated tau proteins– neurons in the entorhinal cortex than the bulk hippocampal tissue. Furthermore, in a series of functional assays, they observed the mutation causing a loss of function in PIN1 and such haploinsufficiency increased the phosphorylation and aggregation of tau proteins.
“Our study provides new insights into the molecular genetic factors behind Alzheimer’s disease and other neurodegenerative diseases potentially linked to somatic mutations in the brain,” said Professor Lee.
The team is planning to expand their study to a larger cohort in order to establish stronger links between these brain somatic mutations and the pathogenesis of Alzheimer’s disease.
(Figure 1. Bioinformatic pipeline for detecting low-level brain somatic mutations in AD and non-AD.)
(Figure 2. Pathogenic brain somatic mutations associated with tau phosphorylation are significantly enriched in AD brains.)
(Figure 3. A pathogenic brain somatic mutation in PIN1 (c. 477 C>T) is a loss-of-function and related functional assays show its haploinsufficiency increases phosphorylation and aggregation of tau.)
2019.07.19 View 34140 -
Nanomaterials Mimicking Natural Enzymes with Superior Catalytic Activity and Selectivity for Detecting Acetylcholine
(Professor Jinwoo Lee from the Department of Chemical and Biomolecular Engineering)
A KAIST research team doped nitrogen and boron into graphene to selectively increase peroxidase-like activity and succeeded in synthesizing a peroxidase-mimicking nanozyme with a low cost and superior catalytic activity. These nanomaterials can be applied for early diagnosis of Alzheimer’s disease.
Enzymes are the main catalysts in our body and are widely used in bioassays. In particular, peroxidase, which oxidizes transparent colorimetric substrates to become a colored product in the presence of hydrogen peroxide, is the most common enzyme that is used in colorimetric bioassays.
However, natural enzymes consisting of proteins are unstable against temperature and pH, hard to synthesize, and costly. Nanozymes, on the other hand, do not consist of proteins, meaning the disadvantages of enzymes can be overcome with their robustness and high productivity. In contrast, most nanonzymes do not have selectivity; for example, peroxidase-mimicking nanozymes demonstrate oxidase-like activity that oxidizes colorimetric substrates in the absence of hydrogen peroxide, which keeps them away from precisely detecting the target materials, such as hydrogen peroxide.
Professor Jinwoo Lee from the Department of Chemical and Biomolecular Engineering and his team were able to synthesize a peroxidase-mimicking nanozyme with superior catalytic activity and selectivity toward hydrogen peroxide. Co-doping of nitrogen and boron into graphene, which has negligible peroxidase-like activity, selectively increased the peroxidase-like activity without oxidase-like activity to accurately mimic the nature peroxidase and has become a powerful candidate to replace the peroxidase.
The experimental results were also verified with computational chemistry. The nitrogen and boron co-doped graphene was also applied to the colorimetric detection of acetylcholine, which is an important neurotransmitter and successfully detected the acetylcholine even better than the nature peroxidase.
Professor Lee said, “We began to study nanozymes due to their potential for replacing existing enzymes. Through this study, we have secured core technologies to synthesize nanozymes that have high enzyme activity along with selectivity. We believe that they can be applied to effectively detect acetylcholine for quickly diagnosing Alzheimer’s disease.
This research, led by PhD Min Su Kim, was published in ACS Nano (10.1021/acsnano.8b09519) on March 25, 2019.
Figure 1. Comparison of the catalytic activities of various nanozymes and horseradish peroxidase (HRP) toward TMB and H₂O₂
Figure 2. Schematic illustration of NB-rGO Reactions in Bioassays
2019.04.30 View 36899 -
Using Light to Treat Alzheimer's Disease
Medical application of photoactive chemicals offers a promising therapeutic strategy for neurodegenerative diseases.
A research team jointly led by Professor Chan Beum Park of the Materials Science and Engineering Department at KAIST and Dr. Kwon Yu from the Bionano Center at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) conducted research to suppress an abnormal assembly of beta-amyloids, a protein commonly found in the brain, by using photo-excited porphyrins.
Beta-amyloid plaques are known to cause Alzheimer's disease. This research finding suggests new ways to treat neurodegenerative illnesses including Alzheimer's disease. It was published online as the lead article in the September 21th issue of Angewandte Chemie. The title of the article is “Photo-excited Porphyrins as a Strong Suppressor of ß-Amyloid Aggregation and Synaptic Toxicity.”
Light-induced treatments using organic photosensitizers have advantages to managing the treatment in time and area. In the case of cancer treatments, doctors use photodynamic therapies where a patient is injected with an organic photosensitizer, and a light is shed on the patient’s lesion. However, such therapies had never been employed to treat neurodegenerative diseases.
Alzheimer's starts when a protein called beta-amyloid is created and deposited in a patient’s brain. The abnormally folded protein created this way harms the brain cells by inducing the degradation of brain functions, for example, dementia. If beta-amyloid creation can be suppressed at an early stage, the formation of amyloid deposits will stop. This could prevent Alzheimer’s disease or halt its progress.
The research team effectively prevented the buildup of beta-amyloids by using blue LED lights and a porphyrin inducer, which is a biocompatible organic compound. By absorbing light energy, a photosensitizer such as porphyrin reaches the excitation state. Active oxygen is created as the porphyrin returns to its ground state. The active oxygen oxidizes a beta-amyloid monomer, and by combining with it, disturbs its assembly.
The technique was tested on drosophilae or fruit flies, which were produced to model Alzheimer on invertebrates. The research showed that symptoms of Alzheimer's disease in the fruit flies such as damage on synapse and muscle, neuronal apoptosis, degradation in motility, and decreased longevity were alleviated. Treatments with light provide additional benefits: less medication is needed than other drug treatments, and there are fewer side effects. When developed, photodynamic therapy will be used widely for this reason.
Professor Park said, “This work has significance as it was the first case to use light and photosensitizers to stop deposits of beta-amyloids. We plan to carry the research further by testing compatibility with other organic and inorganic photosensitizers and by changing the subject of photodynamic therapy to vertebrate such as mice.”
Picture 1 – Deposits of Beta-Amyloid in Fruit Flies Stopped by Using Porphyrin and Blue LED Lights
Picture 2 – The Research Finding Published as the Lead Article in Angewandte Chemie (September 2015)
2015.11.11 View 10525 -
Professor Chan Beum Park, requested for joint international research by a German biotechnology enterprise.
- Bitop AG (Germany) requested a joint development of medicines for Alzheimer’s disease
- The meaning of the financial support by European enterprise to the research result of domestic university.
Professor Chan Beum Park (Department of Materials Science and Engineering in KAIST/ President Nam Pyo Suh) has been entrusted with a joint international research for the development of medicines for Alzheimer’s disease from Bitop AG, German biotechnology enterprise.
KAIST recently agreed with Bitop AG to cooperate for a research program pursuing the development of inhibitors that inhibit the formation of plaque relevant to amyloid diseases like Alzheimer’s disease. Based on this agreement, KAIST will be provided with a financial support of sixty thousands Euro (about 74 million won) from Bitop AG.
Professor Park will perform the screening of inhibitors, which are the core of the research, and KAIST will share patent rights from the research with Bitop AG.
It is known that various degenerative nerve diseases like Alzheimer’s disease, Parkinson’s disease, mad cow disease, and so on arise mainly from the accumulation of pathological protein plaque termed amyloid, and environmental stress accelerates the diseases.
So far, no effective remedy has been developed for amyloid diseases.
Recently, the use of chemicals inhibiting the formation of amyloid has been raised as a potential remedy.
Natural small stress molecules extracted from microbes growing in extreme environments like volcanic region on the bottom of the deep sea, etc. are gaining attention as an amyloid inhibitor.
Professor Park found out for the first time in the world that Anti-stress materials are effective in inhibiting the formation of amyloid plaque and published that fact in several renowned European scientific journals.
After that, Professor Park was requested by Bitop AG for a joint research and has studied for the development of medicines for Alzheimer’s disease using various kinds of Anti-stress materials.
Professor Park said, “I’d like to grant a highly valuable meaning to this entrustment since it implies that European enterprises perceive the value of the research result by domestic universities and hope to promote research and development by providing practical financial support, etc. I wish this time’s entrustment will be a momentum to advance Korea’s research level one step higher through active joint researches with enterprises or institutes in U.S. and Europe as well as Bitop AG.”
Bitop AG is a German enterprise that produces various Anti-stress materials coming from extreme-loving microbes.
Currently, Anti-stress materials are being sold mainly as protein and cell protectants, cosmetic additives, health supplement, etc.
Anti-stress materials extracted from microbes well growing in extreme environment of one hundred centigrade or more are expected to perform a role of inhibitors that inhibit the formation of amyloid plaque, the main factor of stress-related degenerative nerve diseases like Alzheimer’s disease, etc. Such Anti-stress materials are gaining attention as a future medicine for Alzheimer’s disease, etc.
2006.09.05 View 13883