Patients with Alzheimer's disease (AD) develop deposits of aggregated amyloid ?-protein (A?) in the brain. A? accumulation is thought to be a causal event in the etiology of AD. Fibrillar A2 deposits in AD brain are accompanied by innate immune responses such as activated microglia and increased levels of cytokines. Accumulating evidence supports the hypothesis that activated microglia, innate immune cells in the central nervous system, play a pivotal role in the AD progression: either clearing A? deposits by phagocytic activity or releasing cytotoxic substances. Toll-like receptors (TLRs) are a class of pattern-recognition receptors in the innate immune system. One of the important roles of TLRs is to activate phagocytes/microglia to respond to insults including pathogens and damaged host cells, leading to clearance of pathogens, damaged tissues and accumulated wastes. We hypothesize that these protective functions are mediated by MyD88-dependent pathways and that A? load in the brain can be modulated by TLR4 signaling. We will determine the roles of MyD88-dependent pathways and TLR4 signaling in A? clearance by completing the Specific Aim 1 and 2. We further hypothesize that A? load in the brain and cognitive functions are modulated by TLR4 effector cytokines/chemokines, which will be tested by performing Aim 3.
In Aim 4, we will test the hypothesis that accumulation of A? in the brain induces dysfunction of TLR4 signaling in microglia resulting in exacerbation of A? deposition in AD patients and AD mouse models.
Specific Aims are (Aim 1) to determine cerebral A? load, inflammation and behavioral deficits in AD mouse models on a MyD88-deficient genetic background, (Aim 2) to determine cerebral A? load, inflammation and behavioral deficits in AD mouse models that overexpress TLR4, (Aim 3a) to compare cerebral cytokine and chemokine expression profiles between TLR4 wild-type and mutant AD mouse models, (Aim 3b) to overexpress TLR4 effector cytokines and/or chemokines in the brain via adeno-associated virus gene delivery and determine cerebral A? load, inflammation and behavioral deficits in the AD mouse models, and (Aim 4) to determine whether A? induces dysfunction of TLR signaling, using cultured microglia, AD mouse models and tissue samples from AD patients. The long term goal of this research is to determine the roles of TLR signaling and its effector cytokines/chemokines in the AD progression.
Alzheimer's disease (AD) is the most common cause of dementia in the elderly. To date, however, no satisfactory treatments are available for AD. Patients with AD develop deposits of aggregated amyloid 2 protein (A?) in the brain. A? accumulation is thought to be a causal event in the etiology of AD. This study will elucidate the mechanisms by which A? deposits are cleared and serve as a proof of principle to demonstrate if our novel cytokine/chemokine gene therapy modality is effective in treating an animal model of AD.
|Yang, Junling; Kou, Jinghong; Lalonde, Robert et al. (2017) Intracranial IL-17A overexpression decreases cerebral amyloid angiopathy by upregulation of ABCA1 in an animal model of Alzheimer's disease. Brain Behav Immun 65:262-273|
|Yang, Junling; Kou, Jinghong; Lim, Jeong-Eun et al. (2016) Intracranial delivery of interleukin-17A via adeno-associated virus fails to induce physical and learning disabilities and neuroinflammation in mice but improves glucose metabolism through AKT signaling pathway. Brain Behav Immun 53:84-95|
|Go, Michelle; Kou, Jinghong; Lim, Jeong-Eun et al. (2016) Microglial response to LPS increases in wild-type mice during aging but diminishes in an Alzheimer's mouse model: Implication of TLR4 signaling in disease progression. Biochem Biophys Res Commun 479:331-337|
|Kou, Jinghong; Yang, Junling; Lim, Jeong-Eun et al. (2015) Catalytic immunoglobulin gene delivery in a mouse model of Alzheimer's disease: prophylactic and therapeutic applications. Mol Neurobiol 51:43-56|
|Yang, Junling; Pattanayak, Abhinandan; Song, Min et al. (2013) Muscle-directed anti-A? single-chain antibody delivery via AAV1 reduces cerebral A? load in an Alzheimer's disease mouse model. J Mol Neurosci 49:277-88|
|Lalonde, Robert; Fukuchi, Ken-Ichiro; Strazielle, Catherine (2012) Neurologic and motor dysfunctions in APP transgenic mice. Rev Neurosci 23:363-79|
|Lalonde, R; Fukuchi, K; Strazielle, C (2012) APP transgenic mice for modelling behavioural and psychological symptoms of dementia (BPSD). Neurosci Biobehav Rev 36:1357-75|
|Kou, Jinghong; Song, Min; Pattanayak, Abhinandan et al. (2012) Combined treatment of A? immunization with statin in a mouse model of Alzheimer's disease. J Neuroimmunol 244:70-83|
|Lim, Jeong-Eun; Song, Min; Jin, Jingji et al. (2012) The effects of MyD88 deficiency on exploratory activity, anxiety, motor coordination, and spatial learning in C57BL/6 and APPswe/PS1dE9 mice. Behav Brain Res 227:36-42|
|Song, Min; Jin, Jingji; Lim, Jeong-Eun et al. (2011) TLR4 mutation reduces microglial activation, increases A? deposits and exacerbates cognitive deficits in a mouse model of Alzheimer's disease. J Neuroinflammation 8:92|
Showing the most recent 10 out of 12 publications