Single-domain antibody-based noninvasive in vivo imaging of α-synuclein or tau pathology
Jiang, Yixiang; Lin, Yan; Krishnaswamy, Senthilkumar; Pan, Ruimin; Wu, Qian; Sandusky-Beltran, Leslie A; Liu, Mengyu; Kuo, Min-Hao; Kong, Xiang-Peng; Congdon, Erin E; Sigurdsson, Einar M
Intracellular deposition of α-synuclein and tau are hallmarks of synucleinopathies and tauopathies, respectively. Recently, several dye-based imaging probes with selectivity for tau aggregates have been developed, but suitable imaging biomarkers for synucleinopathies are still unavailable. Detection of both of these aggregates early in the disease process may allow for prophylactic therapies before functional impairments have manifested, highlighting the importance of developing specific imaging probes for these lesions. In contrast to the β sheet dyes, single-domain antibodies, found in camelids and a few other species, are highly specific, and their small size allows better brain entry and distribution than whole antibodies. Here, we have developed such imaging ligands via phage display libraries derived from llamas immunized with α-synuclein and tau preparations, respectively. These probes allow noninvasive and specific in vivo imaging of α-synuclein versus tau pathology in mice, with the brain signal correlating strongly with lesion burden. These small antibody derivatives have great potential for in vivo diagnosis of these diseases.
China's Ambitious Policy Experiment with Social Long-Term Care Insurance: Promises, Challenges, and Prospects
Feng, Zhanlian; Lin, Yan; Wu, Bei; Zhuang, Xiaowei; Glinskaya, Elena
In 2016, China launched long-term care insurance (LTCI) pilot programs in 15 cities across the country. In this Commentary, we provide an overview of these pilots regarding the target insured population, sources of financing, beneficiary eligibility criteria, and benefit design. We offer perspectives on the strengths and limitations, implementation challenges, and future prospects of these ongoing pilots. Also, we highlight the needs for addressing several key policy issues and challenges before further expanding these programs toward national implementation. These include solidifying the LTCI financing pool for independence and self-sustainability, balancing national priorities and local needs in LTCI design, reducing coverage gaps and disparities, ensuring quality of care through pay-for-performance and regulatory oversight, and strengthening independent evaluation of LTCI implementation and impacts.
Single domain antibodies targeting pathological tau protein: Influence of four IgG subclasses on efficacy and toxicity
Congdon, Erin E; Pan, Ruimin; Jiang, Yixiang; Sandusky-Beltran, Leslie A; Dodge, Andie; Lin, Yan; Liu, Mengyu; Kuo, Min-Hao; Kong, Xiang-Peng; Sigurdsson, Einar M
BACKGROUND:Eleven tau immunoglobulin G (IgG) antibodies have entered clinical trials to treat tauopathies, including Alzheimer's disease, but it is unclear which IgG subclass/subtype has the ideal efficacy and safety profile. Only two subtypes, with or without effector function, have been examined in the clinic and not for the same tau antibody. The few preclinical studies on this topic have only compared two subtypes of one antibody each and have yielded conflicting results. METHODS:subclasses containing identical tau binding domains but differing Fc region. Unmodified sdAbs and their IgG subclasses were tested for efficacy in primary cultures and in vivo microdialysis using JNPL3 tauopathy mice. FINDINGS/RESULTS:subclasses varied greatly within and between sdAbs. For one of them, all its subtypes were non-toxic, only those with effector function cleared tau, and were more effective in vivo than unmodified sdAb. For the other sdAb, all its subtypes were toxic in tauopathy cultures but not in wild-type cells, suggesting that bivalent binding of its tau epitope stabilizes a toxic conformation of tau, with major implications for tau pathogenesis. Likewise, its subclasses were less effective than the unmodified sdAb in clearing tau in vivo. INTERPRETATION/CONCLUSIONS:These findings indicate that tau antibodies with effector function are safe and better at clearing pathological tau than effectorless antibodies, Furthermore, tau antibodies can provide a valuable insight into tau pathogenesis, and some may aggravate it. FUNDING/BACKGROUND:Funding for these studies was provided by the National Institute of Health (R01 AG032611, R01 NS077239, RF1 NS120488, R21 AG 069475, R21 AG 058282, T32AG052909), and the NYU Alzheimer's Disease Center Pilot Grant Program (via P30 AG008051).
Increased neuronal activity in motor cortex reveals prominent calcium dyshomeostasis in tauopathy mice
Wu, Qian; Bai, Yang; Li, Wei; Congdon, Erin E; Liu, Wenke; Lin, Yan; Ji, Changyi; Gan, Wen-Biao; Sigurdsson, Einar M
Perturbed neuronal Ca2+ homeostasis is implicated in Alzheimer's disease, which has primarily been demonstrated in mice with amyloid-Î² deposits but to a lesser and more variable extent in tauopathy models. In this study, we injected AAV to express Ca2+ indicator in layer II/III motor cortex neurons and measured neuronal Ca2+ activity by two photon imaging in awake transgenic JNPL3 tauopathy and wild-type mice. Various biochemical measurements were conducted in postmortem mouse brains for mechanistic insight and a group of animals received two intravenous injections of a tau monoclonal antibody spaced by four days to test whether the Ca2+ dyshomeostasis was related to pathological tau protein. Under running conditions, we found abnormal neuronal Ca2+ activity in tauopathy mice compared to age-matched wild-type mice with higher frequency of Ca2+ transients, lower amplitude of peak Ca2+ transients and lower total Ca2+ activity in layer II/III motor cortex neurons. While at resting conditions, only Ca2+ frequency was increased. Brain levels of soluble pathological tau correlated better than insoluble tau levels with the degree of Ca2+ dysfunction in tauopathy mice. Furthermore, tau monoclonal antibody 4E6 partially rescued Ca2+ activity abnormalities in tauopathy mice after two intravenous injections and decreased soluble pathological tau protein within the brain. This correlation and antibody effects strongly suggest that the neuronal Ca2+ dyshomeostasis is causally linked to pathological tau protein. These findings also reveal more pronounced neuronal Ca2+ dysregulation in tauopathy mice than previously reported by two-photon imaging that can be partially corrected with an acute tau antibody treatment.
Chronic PD-1 Checkpoint Blockade Does Not Affect Cognition or Promote Tau Clearance in a Tauopathy Mouse Model
Lin, Yan; Rajamohamedsait, Hameetha B; Sandusky-Beltran, Leslie A; Gamallo-Lana, Begona; Mar, Adam; Sigurdsson, Einar M
Programmed cell death protein 1 (PD-1) checkpoint blockade with an antibody has been shown to reduce amyloid-Î² plaques, associated pathologies and cognitive impairment in mouse models. More recently, this approach has shown effectiveness in a tauopathy mouse model to improve cognition and reduce tau lesions. Follow-up studies by other laboratories did not see similar benefits of this type of therapy in other amyloid-Î² plaque models. Here, we report a modest increase in locomotor activity but no effect on cognition or tau pathology, in a different more commonly used tauopathy model following a weekly treatment for 12 weeks with the same PD-1 antibody and isotype control as in the original AÎ²- and tau-targeting studies. These findings indicate that further research is needed before clinical trials based on PD-1 checkpoint immune blockage are devised for tauopathies.
IgE stimulates human and mouse arterial cell apoptosis and cytokine expression and promotes atherogenesis in Apoe-/- mice
Wang, Jing; Cheng, Xiang; Xiang, Mei-Xiang; Alanne-Kinnunen, Mervi; Wang, Jian-An; Chen, Han; He, Aina; Sun, Xinghui; Lin, Yan; Tang, Ting-Ting; Tu, Xin; Sjöberg, Sara; Sukhova, Galina K; Liao, Yu-Hua; Conrad, Daniel H; Yu, Lunyin; Kawakami, Toshiaki; Kovanen, Petri T; Libby, Peter; Shi, Guo-Ping
Corrigendum to "Dynamic assessment of tau immunotherapies in the brains of live animals by two-photon imaging" EBioMedicine 35 (2018) 270-278
Wu, Qian; Lin, Yan; Gu, Jiaping; Sigurdsson, Einar M
Dynamic assessment of tau immunotherapies in the brains of live animals by two-photon imaging
Wu, Qian; Lin, Yan; Gu, Jiaping; Sigurdsson, Einar M
Our original findings, showing the effectiveness of active and passive tau immunizations in mouse models, have now been confirmed and extended by many groups, with several clinical trials underway in Alzheimer's disease and progressive supranuclear palsy. Here, we report on a unique and sensitive two-photon imaging approach to concurrently study the dynamics of brain and neuronal uptake and clearance of tau antibodies as well as the acute removal of their pathological target in live animals. This in vivo technique is more sensitive to detect clearance of pathological tau protein than western blot tau analysis of brain tissue. In addition to providing an insight into the mechanisms involved, it allows for an efficient in vivo assessment of the therapeutic potential of tau antibodies, and may be applied to related protein misfolding diseases.
In Vivo Imaging of Tauopathy in Mice
Krishnaswamy, Senthilkumar; Wu, Qian; Lin, Yan; Rajamohamedsait, Wajitha J; Rajamohamedsait, Hameetha B; Sigurdsson, Einar M
Alzheimer's disease is characterized by amyloid-Î² plaques and neurofibrillary tangles composed of tau aggregates. Several Î²-sheet dyes are already in clinical use to detect amyloid-Î² plaques by in vivo positron emission tomography (PET), and related dye compounds are being developed for targeting pathological tau aggregates. In contrast to Î²-sheet binders, antibody-derived ligands should provide greater specificity for detecting tau lesions, and can be tailored to detect various pathological tau epitopes.For preclinical in vivo evaluation of these ligands prior to PET development, we have established an in vivo imaging system (IVIS) protocol to detect tauopathy in live mice. Antibodies and their derivatives are conjugated with a near infrared fluorescent dye and injected intravenously into anesthetized mice, which subsequently are imaged at various intervals to assess their pathological tau burden, and clearance of the ligand from the brain. The in vivo signal obtained through the skull correlates well with the degree of tau pathology in the mice, and the injected ligand can be found intraneuronally within the brain bound to tau aggregates. Control IgG and injections of the tau antibodies/fragments into wild-type mice or mice with amyloid-Î² plaques lead to minimal or no signal, confirming the specificity of the approach.
Research of gene delivery mediated by ultrasound, microbubble and folate-modified chitosan nanoparticles
Li, Yue; Lin, Yan; Fu, Chun Liu; Tu, Jiawei; Yang, Chaopin; Chen, Zhi Yi
Objective-To study transfection efficiency of folate-modified chitosan (FA-CS) nanoparticles as a non-viral vector delivering pEGFP-C3plasmid (FA-CS/P) to 293T cells with or without the combination of ultrasound and microbubble. Method-pEGFP-C3 was used as reporter gene and FA-CS nanoparticles, which prepared by complex coagulation method were used as biological carriers. Transfection efficiency to 293T cells mediated by FA-CS/P nanoparticles, ultrasound (US) and microbubble (MB) was assessed by fluorescence microscopy and flow cytometry. Result-FA-CS/P nanoparticles have a particle size of 355.1 nm and zeta potential of 10.4 mV. Significant green fluorescence could be observed in CS/P group, FA-CS/P group, US+MB/P group, US+FA-CS/P group, Liposome 2000 (L) group under inverted fluorescence microscope, while US+MB+FA-CS/P group only scattered fluorescence observed. Result of flow cytometry showed that transfection rate of US+MB+FA-CS/P group was (2.0 Â± 0.2)%, which was significantly lower than other groups (Pï¼œ0.05). CCK-8 experiments showed that cell vitality of US+MB+FA-CS/P was (64.1Â±4.6)%, which was also lower than other groups (Pï¼œ0.05). Conclusion-In this study, FA-CS was successfully synthesized. FA-CS could combine with pEGFP-C3 effectively forming nanoparticles with nanoparticle size, well dispersion, high encapsulation efficiency and no significant toxicity to cells. The application of ultrasound increased the transfection rate of FA-CS/P. However, while exposed to ultrasound and microbubble, the transfection rate of FA-CS/P decreased obviously, may indicating that there was no synergistic effect for gene transfection by the combination of ultrasound, folate modified chitosan and microbubbles.