| 1. |
- Bonvicini, Gillian
(author)
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Harnessing the molecular Trojan horse : Evaluating properties of preclinical Aβ immunoPET radioligands for optimized brain delivery via the transferrin receptor
- 2023
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Doctoral thesis (other academic/artistic)abstract
- With high specificity and selectivity to targets, antibodies are prime candidates for positron emission tomography (PET) radioligands. They do not passively cross the blood-brain barrier which has hindered their development for imaging intrabrain targets, like amyloid-β (Aβ) in Alzheimer’s disease. The molecular Trojan horse strategy with antibodies that bind to both the transferrin receptor (TfR) and an intrabrain target improves brain delivery of therapeutic antibodies. However, therapeutic antibodies are typically dosed substantially higher than antibody-based PET (immunoPET) radioligands.This thesis evaluated the effects of affinity, valency, and dose on the brain delivery of preclinical Aβ immunoPET radioligands via the TfR.Paper I investigated whether immunoPET with TfR-mediated brain delivery could image Aβ with similar sensitivity in rats as it has in mice. To our knowledge, this was the first time TfR-hijacking to deliver a radioligand to image Aβ was successfully demonstrated in rats; suggesting this strategy could eventually be translated to clinics.Affinity to TfR influences therapeutic delivery to the brain. In Paper II, we compared four Biacore setups and one on-cell assay for determining apparent affinities to the TfR. Absolute affinity determination was challenging since several assay conditions impacted the kinetic parameters. A directional TfR capture in Biacore may be optimal since it determined kinetic parameters while mimicking in vivo receptor conditions. Papers I and III investigated how antibody affinity affects brain delivery at tracer doses and indicated that stronger TfR affinity yielded higher brain delivery. The antibodies in Paper III lacked effector function. The resulting pharmacokinetic profiles in Aβ pathology-presenting mice indicated this may have improved target accumulation of the immunoPET radioligand.In Paper IV, we screened a novel library of monovalent and bivalent affinity variants of the anti-mouse TfR antibody, 8D3. A pair of monovalent and bivalent antibodies with an apparent affinity of 10 nM was identified and evaluated in vivo. Monovalent binding yielded higher brain uptake at a tracer dose but whether bivalent binding steered the antibody towards lysosomal degradation was unclear.In conclusion, monovalency, high affinity binding, and ablated effector function are likely beneficial properties for TfR-mediated brain delivery of an immunoPET radioligand at a tracer dose.
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| 2. |
- Gkanatsiou, Eleni, et al.
(author)
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Characterization of monomeric and soluble aggregated Aβ in Down's syndrome and Alzheimer's disease brains.
- 2021
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In: Neuroscience letters. - : Elsevier BV. - 1872-7972 .- 0304-3940. ; 754
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Journal article (peer-reviewed)abstract
- The major characteristics of Alzheimer's disease (AD) are amyloid plaques, consisting of aggregated beta amyloid (Aβ) peptides, together with tau pathology (tangles, neuropil treads and dystrophic neurites surrounding the plaques), in the brain. Down's syndrome (DS) individuals are at increased risk to develop AD-type pathology; most DS individuals have developed substantial pathology already at the age of 40. DS individuals have an extra copy of chromosome 21, harbouring the amyloid precursor protein gene (APP). Our aim was to investigate the Aβ peptide pattern in DS and AD brains to investigate differences in their amyloid deposition and aggregation, respectively. Cortical tissue from patients with DS (with amyloid pathology), sporadic AD and controls were homogenized and fractionated into TBS (water soluble) and formic acid (water insoluble) fractions. Immunoprecipitation (IP) was performed using a variety of antibodies targeting different Aβ species including oligomeric Aβ. Mass spectrometry was then used to evaluate the presence of Aβ species in the different patient groups. A large number of Aβ peptides were identified including Aβ1-X, 2-X, 3-X, 4-X, 5-X, 11-X, and Aβ peptides extended N terminally of the BACE1 cleavage site and ending at amino 15 in the Aβ sequence APP/Aβ(-X to 15), as well as peptides post-translationally modified by pyroglutamate formation. Most Aβ peptides had higher abundance in AD and DS compared to controls, except the APP/Aβ(-X to 15) peptides which were most abundant in DS followed by controls and AD. Furthermore, the abundancies of AβX-40 and AβX-34 were increased in DS compared with AD. Aβ1-40, Aβ1-42, and Aβ4-42 were identified as the main constitutes of protofibrils (IP'd using mAb158) and higher relative Aβ1-42 signals were obtained compared with samples IP'd with 6E10+4G8, indicating that the protofibrils/oligomers were enriched with peptides ending at amino acid 42. All Aβ peptides found in AD were also present in DS indicating similar pathways of Aβ peptide production, degradation and accumulation, except for APP/Aβ(-X to 15). Likewise, the Aβ peptides forming protofibrils/oligomers in both AD and DS were similar, implying the possibility that treatment with clinical benefit in sporadic AD might also be beneficial for subjects with DS.
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| 3. |
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| 4. |
- Johannesson, Malin, et al.
(author)
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Elevated soluble amyloid beta protofibrils in Down syndrome and Alzheimer's disease
- 2021
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 114
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Journal article (peer-reviewed)abstract
- Down syndrome (DS) is caused by trisomy of chromosome 21, which leads to a propensity to develop amyloid beta (A beta) brain pathology in early adulthood followed later by cognitive and behavioral deterioration. Characterization of the A beta pathology is important to better understand the clinical deterioration of DS individuals and to identify interventive strategies. Brain samples from people with DS and Alzheimer's disease (AD), as well as nondemented controls (NDC), were analyzed with respect to different A beta species. Immunohistochemical staining using antibodies towards A beta was also performed. Elevated levels of soluble A beta protofibrils and insoluble A beta x-40 and A beta x-42 in formic acid brain extracts, and elevated immunohistochemical staining of A beta deposits were demonstrated with the antibody BAN2401 (lecanemab) in DS and AD compared with NDC. These data and the promising data in a large phase 2 CE clinical trial with lecanemab suggest that lecanemab may have the potential to preserve cognitive capacity in DS. Lecanemab is currently in a phase 3 CE clinical trial.
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| 5. |
- Nordström, Eva, et al.
(author)
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ABBV-0805, a novel antibody selective for soluble aggregated alpha-synuclein, prolongs lifespan and prevents buildup of alpha-synuclein pathology in mouse models of Parkinson's disease
- 2021
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In: Neurobiology of Disease. - : Elsevier. - 0969-9961 .- 1095-953X. ; 161
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Journal article (peer-reviewed)abstract
- A growing body of evidence suggests that aggregated alpha-synuclein, the major constituent of Lewy bodies, plays a key role in the pathogenesis of Parkinson's disease and related alpha-synucleinopathies. Immunotherapies, both active and passive, against alpha-synuclein have been developed and are promising novel treatment strategies for such disorders. Here, we report on the humanization and pharmacological characteristics of ABBV-0805, a monoclonal antibody that exhibits a high selectivity for human aggregated alpha-synuclein and very low affinity for monomers. ABBV-0805 binds to a broad spectrum of soluble aggregated alpha-synuclein, including small and large aggregates of different conformations. Binding of ABBV-0805 to pathological alpha-synuclein was demonstrated in Lewy body-positive post mortem brains of Parkinson's disease patients. The functional potency of ABBV-0805 was demonstrated in several cellular assays, including Fc gamma-receptor mediated uptake of soluble aggregated alpha-synuclein in microglia and inhibition of neurotoxicity in primary neurons. In vivo, the murine version of ABBV-0805 (mAb47) displayed significant dose dependent decrease of alpha-synuclein aggregates in brain in several mouse models, both in prophylactic and therapeutic settings. In addition, mAb47 treatment of alpha-synuclein transgenic mice resulted in a significantly prolonged survival. ABBV-0805 selectively targets soluble toxic alpha-synuclein aggregates with a picomolar affinity and demonstrates excellent in vivo efficacy. Based on the strong preclinical findings described herein, ABBV-0805 has been progressed into clinical development as a potential disease-modifying treatment for Parkinson's disease.
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| 6. |
- Wang, Yanling, et al.
(author)
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In brown adipocytes, adrenergically induced beta(1)-/beta(3)-(G(s))-, alpha(2)-(G(i))- and alpha(1)-(G(q))-signalling to Erk1/2 activation is not mediated via EGF receptor transactivation
- 2013
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In: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 319:17, s. 2718-2727
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Journal article (peer-reviewed)abstract
- Brown adipose tissue is unusual in that the neurotransmitter norepinephrine influences cell destiny in ways generally associated with effects of classical growth factors: regulation of cell proliferation, of apoptosis, and progression of differentiation. The norepinephrine effects are mediated through G-protein-coupled receptors; further mediation of such stimulation to e.g. Erk1/2 activation is in cell biology in general accepted to occur through transactivation of the EGF receptor (by external or internal pathways). We have examined here the significance of such transactivation in brown adipocytes. Stimulation of mature brown adipocytes with cirazoline (alpha(1)-adrenoceptor coupled via G(q)), clonidine (alpha(2) via G(i)) or CL316243 (beta(3) via G(s)) or via beta(1)-receptors significantly activated Erk1/2. Pretreatment with the EGF receptor kinase inhibitor AG1478 had, remarkably, no significant effect on Erk1/2 activation induced by any of these adrenergic agonists (although it fully abolished EGF-induced Erk1/2 activation), demonstrating absence of EGF receptor-mediated transactivation. Results with brown preadipocytes (cells in more proliferative states) were not qualitatively different. Joint stimulation of all adrenoceptors with norepinephrine did not result in synergism on Erk1/2 activation. AG1478 action on EGF-stimulated Erk1/2 phosphorylation showed a sharp concentration response relationship (IC50 0.3 mu M); a minor apparent effect of AG1478 on norepinephrine-stimulated Erk1/2 phosphorylation showed nonspecific kinetics, implying caution in interpretation of partial effects of AG1478 as reported in other systems. Transactivation of the EGF receptor is clearly not a universal prerequisite for coupling of G-protein coupled receptors to Erk1/2 signalling cascades.
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| 7. |
- Wang, Yanling, 1982-, et al.
(author)
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In brown adipocytes, adrenergically induced β1-/β3-(Gs)-, α2-(Gi)- and α1-(Gq)-mediated Erk1/2 activation is not mediated via EGF receptor transactivation
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Journal article (other academic/artistic)abstract
- Brown adipose tissue is unusual in utilising the neurotransmitter norepineph- rine to influence cell destiny in ways generally associated with classical growth factors: regulation of cell proliferation, apoptosis, progression of differentiation. These effects are thus mediated through G-protein-coupled receptors; mediation of such stimulation to e.g. Erk1/2 activation is generally accepted to occur through transactivation of the EGF receptor (by external or internal pathways). We have examined here the significance of such transac- tivation in brown adipocytes. Stimulation of mature brown adipocytes with cirazoline (α1-adrenoceptor coupled via Gq), clonidine (α2 via Gi) or CL316243 (β3 via Gs) significantly activated Erk1/2. Pretreatment with the EGF receptor kinase inhibitor AG1478 had, remarkably, no significant effect on Erk1/2 activation induced by any of the adrenergic agonists (although it fully abolished EGF-induced Erk1/2 activation), demonstrating absence of transactivation. Results with brown adipocytes in more proliferative states were not qualitatively different. Joint stimulation of all adrenoceptors with norepinephrine did not result in synergism on Erk1/2 activation or in occur- rence of transactivation. AG1478 action on EGF-stimulated Erk1/2 phos- phorylation showed a sharp concentration-response relationship with an IC50 of approx. 0.3 μM; a minor effect of AG1478 on norepinephrine- stimulated Erk1/2 phosphorylation was clearly nonspecific, occurring suc- cessively and only partially over 3 decades of AG1478 concentrations; cau- tion may therefore be required in interpretation of effects of AG1478 at higher concentrations. Transactivation of the EGF receptor is clearly not a universal prerequisite for coupling of G-protein coupled receptors to Erk1/2 signaling cascades.
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