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- All Subjects: Alzheimer's Disease
- Creators: Velazquez, Ramon
- Creators: Sierks, Michael
Description
Alzheimer's Disease (AD) is a debilitating neurodegenerative disease. The disease leads to dementia and loss of cognitive functions and affects about 4.5 million people in the United States. It is the 7th leading cause of death and is a huge financial burden on the healthcare industry. There are no means of diagnosing the disease before neurodegeneration is significant and sadly there is no cure that controls its progression. The protein beta-amyloid or Aâ plays an important role in the progression of the disease. It is formed from the cleavage of the Amyloid Precursor Protein by two enzymes - â and ã-secretases and is found in the plaques that are deposits found in Alzheimer brains. This work describes the generation of therapeutics based on inhibition of the cleavage by â-secretase. Using in-vitro recombinant antibody display libraries to screen for single chain variable fragment (scFv) antibodies; this work describes the isolation and characterization of scFv that target the â-secretase cleavage site on APP. This approach is especially relevant since non-specific inhibition of the enzyme may have undesirable effects since the enzyme has been shown to have other important substrates. The scFv iBSEC1 successfully recognized APP, reduced â-secretase cleavage of APP and reduced Aâ levels in a cell model of Alzheimer's Disease. This work then describes the first application of bispecific antibody therapeutics to Alzheimer's Disease. iBSEC1 scFv was combined with a proteolytic scFv that enhances the "good" pathway (á-secretase cleavage) that results in alternative cleavage of APP to generate the bispecific tandem scFv - DIA10D. DIA10D reduced APP cleavage by â-secretase and steered it towards the "good" pathway thus increasing the generation of the fragment sAPPá which is neuroprotective. Finally, treatment with iBSEC1 is evaluated for reduced oxidative stress, which is observed in cells over expressing APP when they are exposed to stress. Recombinant antibody based therapeutics like scFv have several advantages since they retain the high specificity of the antibodies but are safer since they lack the constant region and are smaller, potentially facilitating easier delivery to the brain
ContributorsBoddapati, Shanta (Author) / Sierks, Michael (Thesis advisor) / Arizona State University (Publisher)
Created2011
Description
Patients with Alzheimer's disease (AD) exhibit a significantly higher incidence of unprovoked seizures compared to age-matched non-AD controls, and animal models of AD (i.e., transgenic human amyloid precursor protein, hAPP mice) display neural hyper-excitation and epileptic seizures. Hyperexcitation is particularly important because it contributes to the high incidence of epilepsy in AD patients as well as AD-related synaptic deficits and neurodegeneration. Given that there is significant amyloid-β (Aβ) accumulation and deposition in AD brain, Aβ exposure ultimately may be responsible for neural hyper-excitation in both AD patients and animal models. Emerging evidence indicates that α7 nicotinic acetylcholine receptors (α7-nAChR) are involved in AD pathology, because synaptic impairment and learning and memory deficits in a hAPPα7-/- mouse model are decreased by nAChR α7 subunit gene deletion. Given that Aβ potently modulates α7-nAChR function, that α7-nAChR expression is significantly enhanced in both AD patients and animal models, and that α7-nAChR play an important role in regulating neuronal excitability, it is reasonable that α7-nAChRs may contribute to Aβ-induced neural hyperexcitation. We hypothesize that increased α7-nAChR expression and function as a consequence of Aβ exposure is important in Aβ-induced neural hyperexcitation. In this project, we found that exposure of Aβ aggregates at a nanomolar range induces neuronal hyperexcitation and toxicity via an upregulation of α7-nAChR in cultured hippocampus pyramidal neurons. Aβ up-regulates α7-nAChRs function and expression through a post translational mechanism. α7-nAChR up-regulation occurs prior to Aβ-induced neuronal hyperexcitation and toxicity. Moreover, inhibition of α7-nAChR or deletion of α7-nAChR prevented Aβ induced neuronal hyperexcitation and toxicity, which suggests that α7-nAChRs are required for Aβ induced neuronal hyperexcitation and toxicity. These results reveal a profound role for α7-nAChR in mediating Aβ-induced neuronal hyperexcitation and toxicity and predict that Aβ-induced up-regulation of α7-nAChR could be an early and critical event in AD etiopathogenesis. Drugs targeting α7-nAChR or seizure activity could be viable therapies for AD treatment.
ContributorsLiu, Qiang (Author) / Wu, Jie (Thesis advisor) / Lukas, Ronald J (Committee member) / Chang, Yongchang (Committee member) / Sierks, Michael (Committee member) / Smith, Brian (Committee member) / Vu, Eric (Committee member) / Arizona State University (Publisher)
Created2011
Description
Specificity and affinity towards a given ligand/epitope limit target-specific delivery. Companies can spend between $500 million to $2 billion attempting to discover a new drug or therapy; a significant portion of this expense funds high-throughput screening to find the most successful target-specific compound available. A more recent addition to discovering highly specific targets is the application of phage display utilizing single chain variable fragment antibodies (scFv). The aim of this research was to employ phage display to identify pathologies related to traumatic brain injury (TBI), particularly astrogliosis. A unique biopanning method against viable astrocyte cultures activated with TGF-β achieved this aim. Four scFv clones of interest showed varying relative affinities toward astrocytes. One of those four showed the ability to identify reactive astroctyes over basal astrocytes through max signal readings, while another showed a statistical significance in max signal reading toward basal astrocytes. Future studies will include further affinity characterization assays. This work contributes to the development of targeting therapeutics and diagnostics for TBI.
ContributorsMarsh, William (Author) / Stabenfeldt, Sarah (Thesis advisor) / Caplan, Michael (Committee member) / Sierks, Michael (Committee member) / Arizona State University (Publisher)
Created2013
Description
Alzheimer's Disease (AD) is a progressive neurodegenerative disease accounting for 50-80% of dementia cases in the country. This disease is characterized by the deposition of extracellular plaques occurring in regions of the brain important for cognitive function. A primary component of these plaques is the amyloid-beta protein. While a natively unfolded protein, amyloid-beta can misfold and aggregate generating a variety of different species including numerous different soluble oligomeric species some of which are precursors to the neurofibrillary plaques. Various of the soluble amyloid-beta oligomeric species have been shown to be toxic to cells and their presence may correlate with progression of AD. Current treatment options target the dementia symptoms, but there is no effective cure or alternative to delay the progression of the disease once it occurs. Amyloid-beta aggregates show up many years before symptoms develop, so detection of various amyloid-beta aggregate species has great promise as an early biomarker for AD. Therefore reagents that can selectively identify key early oligomeric amyloid-beta species have value both as potential diagnostics for early detection of AD and as well as therapeutics that selectively target only the toxic amyloid-beta aggregate species. Earlier work in the lab includes development of several different single chain antibody fragments (scFvs) against different oligomeric amyloid-beta species. This includes isolation of C6 scFv against human AD brain derived oligomeric amyloid-beta (Kasturirangan et al., 2013). This thesis furthers research in this direction by improving the yields and investigating the specificity of modified C6 scFv as a diagnostic for AD. It is motivated by experiments reporting low yields of the C6 scFv. We also used the C6T scFv to characterize the variation in concentration of this particular oligomeric amyloid-beta species with age in a triple transgenic AD mouse model. We also show that C6T can be used to differentiate between post-mortem human AD, Parkinson's disease (PD) and healthy human brain samples. These results indicate that C6T has potential value as a diagnostic tool for early detection of AD.
ContributorsVenkataraman, Lalitha (Author) / Sierks, Michael (Thesis advisor) / Rege, Kaushal (Committee member) / Pauken, Christine (Committee member) / Arizona State University (Publisher)
Created2013
Description
The goal of this thesis is to test whether Alzheimer's disease (AD) is associated with distinctive humoral immune changes that can be detected in plasma and tracked across time. This is relevant because AD is the principal cause of dementia, and yet, no specific diagnostic tests are universally employed in clinical practice to predict, diagnose or monitor disease progression. In particular, I describe herein a proteomic platform developed at the Center for Innovations in Medicine (CIM) consisting of a slide with 10.000 random-sequence peptides printed on its surface, which is used as the solid phase of an immunoassay where antibodies of interest are allowed to react and subsequently detected with a labeled secondary antibody. The pattern of antibody binding to the microarray is unique for each individual animal or person. This thesis will evaluate the versatility of the microarray platform and how it can be used to detect and characterize the binding patterns of antibodies relevant to the pathophysiology of AD as well as the plasma samples of animal models of AD and elderly humans with or without dementia. My specific aims were to evaluate the emergence and stability of immunosignature in mice with cerebral amyloidosis, and characterize the immunosignature of humans with AD. Plasma samples from APPswe/PSEN1-dE9 transgenic mice were evaluated longitudinally from 2 to 15 months of age to compare the evolving immunosignature with non-transgenic control mice. Immunological variation across different time-points was assessed, with particular emphasis on time of emergence of a characteristic pattern. In addition, plasma samples from AD patients and age-matched individuals without dementia were assayed on the peptide microarray and binding patterns were compared. It is hoped that these experiments will be the basis for a larger study of the diagnostic merits of the microarray-based immunoassay in dementia clinics.
ContributorsRestrepo Jimenez, Lucas (Author) / Johnston, Stephen A. (Thesis advisor) / Chang, Yung (Committee member) / Reiman, Eric (Committee member) / Sierks, Michael (Committee member) / Arizona State University (Publisher)
Created2011
Description
Alzheimer's disease (AD), which currently affects approximately 5.4 million Americans, is a type of dementia, which causes memory, cognitive, and behavioral problems. AD is among the top 10 leading causes of death in the United States, typically affecting people ages 65 and older. Beta-Amyloid (Aβ) is an Alzheimer's target protein, which starts as a single protein, but can misfold and bind to itself, forming larger chains and eventually fibrils and plaques of Aβ in the brain. Antibodies that bind to different regions and sizes of Aβ may prevent progression into a more toxic stage. The antibody worked with in this thesis, A4 scFv, binds to oligomeric Aβ. The objective of this antibody research is to optimize the production of functional antibodies, specifically A4, through modifications in the scFv growth process, in order to enhance the discovery of possible diagnostics and therapeutics for Alzheimer's disease. In order to produce functional A4 antibody, four complex sugars were tested in the E. Coli bacterial culture growth media that expresses the desired antibody. The sugars: sucrose, glucose, mannitol, and sorbitol were used in the growth process to improve the yield of functional antibody. Through the steps of growth, purification, and dialysis, the sugar sorbitol was found to provide the optimal results of ending functional antibody concentration. Once an ample amount of functional A4 scFv is produced, it can be used in assays as a biomarker for Alzheimer's disease.
ContributorsDolberg, Taylor Brianne (Author) / Sierks, Michael (Thesis director) / Nielsen, David (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
The research objective is to maintain the A4 nanobody stability during dialysis. Various dialysis buffers were tested and compared, including PBS with varying amounts of the detergent, Tween: low, high, none. Furthermore, PBS, Tris, and HEPES, were tested and compared. PBS without Tween was the worst for preserving A4 stability. PBS was determined to be a better dialysis buffer than Tris or HEPES. To find the optimum buffer, other buffers will be tested and compared with PBS; methods such as gravity filtration and lyophilization will be considered as alternatives to dialysis.
ContributorsTao, Kevin Huang (Author) / Sierks, Michael (Thesis director) / Williams, Stephanie (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
This project aims to address the current protocol regarding the diagnosis and treatment of traumatic brain injury (TBI) in medical industries around the world. Although there are various methods used to qualitatively determine if TBI has occurred to a patient, this study attempts to aid in the creation of a system for quantitative measurement of TBI and its relative magnitude. Through a method of artificial evolution/selection called phage display, an antibody that binds highly specifically to a post-TBI upregulated brain chondroitin sulfate proteoglycan called neurocan has been identified. As TG1 Escheria Coli bacteria were infected with KM13 helper phage and M13 filamentous phage in conjunction, monovalent display of antibody fragments (ScFv) was performed. The ScFv bind directly to the neurocan and from screening, phage that produced ScFv's with higher affinity and specificity to neurocan were separated and purified. Future research aims to improve the ScFv characteristics through increased screening toward neurocan. The identification of a highly specific antibody could lead to improved targeting of neurocan post-TBI in-vivo, aiding researchers in quantitatively defining TBI by visualizing its magnitude.
ContributorsSeelig, Timothy Scott (Author) / Stabenfeldt, Sarah (Thesis director) / Ankeny, Casey (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2015-05
Description
Alzheimer’s disease (AD) is characterized by the aberrant accumulation and aggregation of proteins that in turn contribute to learning and memory deficits. The mammalian target of rapamycin (mTOR) plays an essential role in regulating the synthesis and degradation of proteins that contribute to cell growth and learning and memory. Hyperactivity of mTOR can cause detrimental effects to protein homeostasis and has been linked to AD. The proline-rich Akt-substrate 40 kDa (PRAS40) is a negative regulator of mTOR, as it binds to mTOR directly, reducing its activity. Upon phosphorylation, PRAS40 detaches from mTOR thereby releasing its inhibitory effects. Increased phosphorylation of PRAS40, and a subsequent increase in mTOR activity has been linked to diabetes, cancer, and other conditions; however, PRAS40’s direct role in the pathogenesis of AD is still unclear. To investigate the role of PRAS40 in AD pathology, we generated a PRAS40 conditional knockout mouse model and, using a neuronal-specific Cre recombinase, selectively removed PRAS40 from APP/PS1 mice. Removing neuronal PRAS40 exacerbated Abeta levels and plaque load but paradoxically had no significant effects on mTOR signaling. Mechanistically, the increase in Abeta pathology was linked to a decrease in autophagy function. Our data highlight a primary role of PRAS40 in the pathogenesis of AD.
ContributorsSurendra, Likith (Author) / Oddo, Salvatore (Thesis director) / Velazquez, Ramon (Committee member) / Pratico, Domenico (Committee member) / School of Life Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Dementia is a collective term used to describe symptoms of cognitive impairment in learning and memory. The most prevalent form of dementia is Alzheimer’s disease (AD). In order to understand the pathological mechanisms associated with AD, animal models have been created. These various mouse models replicate the pathology found in humans with AD. As a consequence of the fact that this disease impairs cognitive abilities in humans, testing apparatuses have been developed to measure impaired cognition in animal models. One of the most common behavioral apparatuses that has been in use for nearly 40 years is the Morris water maze (MWM). In the MWM, animals are tasked to find a hidden platform in a pool of water and thereby are subjected to stress that can unpredictably influence cognitive performance. In an attempt to circumvent such issues, the IntelliCage was designed to remove the external stress of the human experimenter and provide a social environment during task assessment which is fully automated and programable. Additionally, the motivation is water consumption, which is less stressful than escaping a pool. This study examined the difference in performance of male and female cohorts of APP/PS1 and non-transgenic (NonTg) mice in both the MWM and the IntelliCage. Initially, 12-month-old male and female APP/PS1 and NonTg mice were tested in the hippocampal-dependent MWM maze for five days. Next, animals were moved to the IntelliCage and underwent 39 days of testing to assess prefrontal cortical and hippocampal function. The results of this experiment showed significant sex differences in task performance, but inconsistency between the two testing paradigms. Notably, males performed significantly better in the MWM, which is consistent with prior research. Interestingly however, APP/PS1 females showed higher Amyloid-β plaque load and performed significantly better in the more complex tasks of the IntelliCage. This suggests that Aβ plaque load may not directly contribute to cognitive deficits, which is consistent with recent reports in humans with AD. Collectively, these results should inform scientists about the caveats of behavioral paradigms and will aid in determining translation to the human condition.
ContributorsMifflin, Marc Anthony (Author) / Velazquez, Ramon (Thesis director) / Mastroeni, Diego (Committee member) / School of Geographical Sciences and Urban Planning (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05