This study demonstrates relevance of the PSEN1 pigs to study AD and suggests necessary refinements to study AD pathogenesis using the PSEN1 pigs.
Abstract
Previously, a clinically relevant swine model (PSEN1ΔE9/+) has been established by utilizing genome editing system to study early onset Alzheimer's Disease (EO-AD). Cognitive assessments and MRI scans of their brain indicate that these pigs carry cognitive deficiencies and abnormal brain physiology, respectively, demonstrating their relevance to study AD. This study was conducted to characterize cell morphology and distributions in the brain cortex and hippocampus of PSEN1ΔE9/+ and wildtype (WT) pigs at 12-14 months of age. First, we quantified the level of APP, Tau, GFAP, and Iba1 proteins in their brain using western blotting. There were no statistically significant differences in Tau and GFAP concentrations in PSEN1 and WT pigs (n=3 per model) but there was a numerical increase in Tau and GFAP in PSEN1 pigs. Next, we examined if the localization of A[beta] and Tau proteins in the brain cortex and hippocampus were different between PSEN1 and WT pigs. Brains from PSEN1 and WT pigs (12-14 months old) were collected, fixed, then immunofluorescent staining was performed to identify Amyloid-beta protein plaques (A[beta]), Tau protein (Tau), reactive microglia (Iba1), astrocytes (GFAP), neurons (NeuN), and nuclei (DAPI) in age-matched PSEN1 and WT brains. PSEN1 pigs had statistically higher Amyloid-beta and Iba1 expression and number of microglia in the cortex than WT pigs. Tau signaling and numbers of neurons were numerically lower in PSEN1 animals than WT. The morphology and cell count of microglia and astrocytes showed early signs of gliosis and pro-inflammatory responses in the brain. The hippocampus analysis did not yield conclusive results, possible due to the animals not being aged long enough. This study demonstrates relevance of the PSEN1 pigs to study AD and suggests necessary refinements to study AD pathogenesis using the PSEN1 pigs.
BACKGROUND
Alzheimer's disease (AD) is characterized by pathological changes in Aβ&Tau, cognitive impairment, and may also manifest psychiatric symptoms. Zonisamide (ZNS) has been demonstrated its improvement of cognitive dysfunction in T2DM mice in our previous study. However, the efficacy and mechanism of ZNS in treating AD remain unclear.
AIM
We aims to investigate the therapeutic efficacy of ZNS for AD and its potential molecular mechanisms.
METHODS
Three-month-old 5xFAD mice were treated with ZNS (20 mg/kg, i.p.) for 12-week. The behavioral test assesses cognitive function and psychiatric symptoms. Aβ-PET/CT, immunofluorescence, and Thioflavine-S stainin staining assessed the levels of Aβ plaques. Proteomics and Western blot analyses evaluated synapse-associated proteins, amyloid precursor protein (APP) related proteins and phosphorylated tau.
RESULTS
We discovered for the first time that ZNS significantly improved spatial learning and memory, and also alleviated psychiatric symptoms in 5xFAD. Besides, ZNS increased PSD95, SYP, BDNF, and SAP90/PSD-95-related protein 3 (SAPAP3), which plays a crucial role in compulsive-like behaviors. Importantly, siRNA-mediated knockdown of SAPAP3 in N2A/APP cells inhibited the regulatory effect of ZNS on PSD95 and NMDAR2A (NR2A). In addition, ZNS treatment reduced Aβ deposition in the brain. It also downregulated APP, p-APP (Thr668), BACE1, and PS1, and attenuated tau phosphorylation at Ser396 by inhibiting its upstream kinase ERK1/2 activity.
CONCLUSION
ZNS exerts neuroprotective effects in 5xFAD mice and improves AD-related cognitive impairment and AD-like lesions, which establishes ZNS as a promising therapeutic avenue for AD and its associated psychiatric symptoms.
Fangtai Yi, Jianfeng Ma, Ruiyue Zhao et al.· European Journal of Pharmaco...· 0 citations
Alzheimer’s Disease (AD) is one of the most prominent neurodegenerative diseases. The disease is associated with amyloid-β (Aβ) accumulation, protein tau neurofibrillary tangles, neuronal loss, and chronic inflammation in the brain. Aβ plaque accumulation leads to an inflammatory response orchestrated by resident microglia and ultimately neurodegeneration. Recent literature suggests that the immune system, particularly antibodies, plays a key role in disease progression. We sought to characterize the role of specific antibodies in AD by manipulating the repertoire of the 5XFAD model system.
We crossed MD4 mice, which have a B cell repertoire restricted to an irrelevant antigen, with 5XFAD mice, which model early onset Alzheimer’s disease, to address whether specific antibodies modulate disease progression. These mice underwent a battery of behavioral tests to measure cognitive impairment, followed by tissue collection for analysis of plaque accumulation, microglia activation, and antibody deposition by immunohistochemistry (IHC).
Analysis of 5XFAD brains using monoclonal antibodies specific for IgG subclasses revealed an increase in microglia-associated IgG1 within the hippocampus compared to non-transgenic littermates. MD4 5XFAD double transgenic mice had sex specific increases in cognitive impairment, including increased mobility in the open field, nighttime hyperactivity, and decreased spontaneous alternation in a cross-maze compared to 5XFAD littermates. By IHC, we detected a modest trending increase in amyloid-β plaque accumulation at 10 months of age in double transgenic mice compared to 5xFAD brain. The wildtype and MD4 mice brains did not display any amyloid-β plaque accumulation, as expected.
Our results suggest that specific antibodies restrict the progression of cognitive impairment in 5XFAD mice. Ongoing work is aimed at uncovering the specificities and origin of the spontaneous antibodies that can be found within the brains of 5XFAD mice.
The National Institute of Health (NIH)
Neuroimmunology (NEUR)
Kanakendu Gupta, P. Gearhart, Braxton D. Greer· Journal of Immunology· 0 citations
BackgroundThe prominent pathological features of Alzheimer's disease (AD) are amyloid-β (Aβ) plaques and tau pathology. The complement cascade is closely related to AD-associated pathological processes; however, the precise mechanisms underlying its contributions remain incompletely elucidated.ObjectiveWe aim to investigate the changes in complement protein expression during AD progression.MethodsThis study enrolled 285 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Participants were classified into biomarker-defined groups based on predefined cutoff values for Aβ42 and phosphorylated tau (P-tau). We compared cerebrospinal fluid (CSF) levels of complement proteins (C1q, C2, C3, C4a, C5, C6, C8b, and factor B) across these subgroups. Furthermore, we explored their associations with core AD biomarkers (Aβ42, P-tau, and T-tau) and clinical characteristics. Additionally, we investigated age-related changes in complement gene expression within the cerebral cortex of 3xTg mice using single-nucleus RNA sequencing.ResultsComplement protein levels in the CSF of A + subjects were significantly lower than those in A- subjects, and complement protein levels were positively correlated with Aβ pathology. Complement protein levels were influenced by factors such as age, gender, body mass index, APOE genotype, and hypertension. Compared with control mice, the complement gene C1qa in microglia was upregulated throughout the entire pathological cycle in 3xTg AD mice.ConclusionsComplement proteins undergo significant changes during the pathogenesis of AD, and alterations in their levels may reflect early pathological changes in AD and warrant further investigation. Notably, our findings suggest that microglia may contribute to complement-mediated pathological processes associated with AD.
Ying-Tong Lu, Zi Guo, Meng-Yuan Liu et al.· Journal of Alzheimer's Disea...· 0 citations
Alzheimer's disease (AD) is a neurodegenerative disorder that significantly impacts millions globally, with rising prevalence among the aging population, emphasizing the need for effective interventions. Isoleucine, a branched-chain amino acid, crosses the blood-brain barrier and plays a role in various neurological disorders. In this study, we investigated the association of isoleucine with AD traits using the BXD mouse reference population, revealing significant correlations with Y-maze performance, anxiety assays, contextual fear conditioning, and the age of onset for working memory deficits. In vitro, exogenous isoleucine supplementation in HT22 and PC12 cells increased amyloid precursor protein (APP) and phosphorylated tau (p-tau) levels. Subsequent analysis identified 2,000 probes correlated with isoleucine and revealed STAT3 as a candidate downstream regulator. Overexpression of STAT3 increased APP and p-tau levels, and STAT3 inhibition abolished this effect, suggesting that isoleucine modulates AD progression via STAT3 activation. Mendelian randomization analysis further supported a causal relationship between elevated isoleucine levels and AD risk. This work provides insights into isoleucine as a potential risk factor for AD and identifies STAT3 as a mediator of isoleucine-related AD susceptibility.
Alzheimer's disease (AD) is characterized by the appearance of brain pathology decades prior to clinical symptoms. The pre-symptomatic phase of AD provides opportunity for early detection and intervention. One early intervention that has been proposed is the use of non-steroidal anti-inflammatory drugs (NSAIDs), such as naproxen. However, evidence suggests that effects of naproxen intervention differ with stage of the disease, and the optimal intervention time is not clear. Accordingly, in this study, we investigated the impact of the timing of naproxen treatment in a rat model of AD. We used the TgF344-AD rat model of AD which develops characteristic pathological features of human AD, including abundant amyloid plaque pathology, astrogliosis, and microgliosis by 6 months of age, and neurofibrillary tangles and neuronal loss by 16 months of age. We examined the effects of naproxen treatment beginning at 1, 4, and 10 months of age in transgenic (Tg) animals and their wild-type (WT) littermates. We used longitudinal in vivo magnetic resonance spectroscopy (MRS) to study the impact of naproxen treatment on hippocampus neurochemistry. Previous studies have used MRS to non-invasively characterize the trajectory of altered hippocampal neurochemistry across the lifespan in the TgF344-AD rat model. In the current study, we employed MRS at 4, 10, and 16 months, i.e. prior to or after the appearance of amyloidosis and gliosis (6 months) and tau pathology (16 months), respectively, in Tg animals. Naproxen treatment altered neurochemistry in Tg animals only if administered beginning at 1 or 4 months of age, mitigating an otherwise observed increase in total choline and decrease in taurine. A more subtle effect was observed on the otherwise-expected increase in myo-inositol. These results highlight the possibility that earlier naproxen intervention could have distinct neurochemical effects compared to delayed treatment, though mechanistic implications remain to be clarified. Moreover, these findings support the use of MRS as a useful non-invasive method of monitoring treatment-related changes in neurochemistry in transgenic animal models.
Caitlin F. Fowler, Elena Osipyan, Gabriel A. Devenyi et al.· Neurochemistry International· 0 citations
ABSTRACT Alzheimer's disease (AD), a neurodegenerative disorder and the most common cause of dementia, has no cure or effective treatment; thus, identification of disease‐modifying therapeutics is crucial. Nrf2 is a master controller of homeostatic functions whose activity is compromised in AD. Most pharmacological Nrf2 activators are electrophilic molecules that covalently modify cysteine residues in the thiol‐rich Keap1, and many are Michael acceptors, such as low‐molecular‐weight (LMW) skin allergens. However, LMW allergens‐induced Nrf2 activation in a pharmacological setting has only recently attracted attention, exemplified by the clinical success of Dimethyl Fumarate. Hence, we investigated, for the first time, the potential of the skin allergen Isoeugenol to activate Nrf2 and reverse selected AD hallmarks, both in vitro and in vivo, in AD‐specific models. In vitro studies were performed using microglia cells exposed to LPS and neuronal cells overexpressing human APP with Swedish mutation, to evaluate Isoeugenol's potential in decreasing neuroinflammation and activating the Nrf2 pathway, respectively. In vivo studies were conducted in 10‐month‐old AD double‐transgenic mice (APP/PS1), which were intranasally administered Isougenol. Isoeugenol's pharmacokinetic and pharmacodynamic profile, and its effect on mice cognition were evaluated. The results showed that Isoeugenol (1) activated Nrf2 in AD neuronal cells (likely involving AKT signaling); (2) exhibited antioxidant and Nrf2‐dependent anti‐inflammatory activity, which was abolished after Nrf2 silencing; (3) exhibited good pharmacokinetic and pharmacodynamic profiles; (4) reduced the levels of Aβ peptides in vitro and in vivo; (5) reduced triglyceride and LDL cholesterol levels in treated mice; and (6) improved the memory deficits in old mice. This is the first study reporting Isoeugenol's intranasal administration, and on specific AD mice models. Overall, the results reinforce Isoeugenol as a pleiotropic molecule, with great potential for AD treatment.
Ana Silva, Sónia Silva, Jéssica Macedo et al.· The FASEB Journal· 0 citations