Treatment of the CRND8 mouse model for cerebral amyloid angiopathy, exhibited increased levels of neuron specific enolase in brain tissue following long-term treatment with a modified C5a receptor agonist, accompanied by improved cognitive function.

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder characterized by amyloid plaques, neurofibrillary tangles, and cerebral amyloid angiopathy (CAA). CAA is a condition manifesting as amyloid deposits in the cerebral vasculature, eventually leading to microhemorrhage. Here, we have treated the CRND8 mouse model with the C5a agonist (EP67) in order to observe the effects on cerebral amyloidosis, CAA, and hyperphosphorylated tau. EP67 attaches to the C5a receptor on phagocytes and stimulates the engulfment and digestion of fibrillar and prefibrillar amyloid while exhibiting minimal inflammation. Older CRND8 mice and their respective controls were treated with EP67 for a prolonged period of time. Following treatment, the CRND8 mice displayed improved spatial memory, while both amyloid deposition and tau hyperphosphorylation were found to be diminished.

Preliminary In Vitro and In Vivo Insights of In Silico Candidate Repurposed Drugs for Alzheimer's Disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease and is the most common type of dementia. Although a considerably large amount of money has been invested in drug development for AD, no disease modifying treatment has been detected so far. In our previous work, we developed a computational method to highlight stage-specific candidate repurposed drugs against AD. In this study, we tested the effect of the top 13 candidate repurposed drugs that we proposed in our previous work in a severity stage-specific manner using an in vitro BACE1 assay and the effect of a top-ranked drug from the list of our previous work, tetrabenazine (TBZ), in the 5XFAD as an AD mouse model. From our in vitro screening, we detected 2 compounds (clomiphene citrate and Pik-90) that showed statistically significant inhibition against the activity of the BACE1 enzyme. The administration of TBZ at the selected dose and therapeutic regimen in 5XFAD in male and female mice showed no significant effect in behavioral tests using the Y-maze and the ELISA immunoassay of Aß40. To our knowledge, this is the first time the drug tetrabenazine has been tested in the 5XFAD mouse model of AD in a sex-stratified manner. Our results highlight 2 drugs (clomiphene citrate and Pik-90) from our previous computational work for further investigation.

Pharmacological activation of the C5a receptor leads to stimulation of the ß-adrenergic receptor and alleviates cognitive impairment in a murine model of familial Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease of the brain causing either familial or sporadic dementia. We have previously administered the modified C5a receptor agonist (EP67) for a short period to a transgenic mouse model of AD (5XFAD) and have observed not only reduction in ß-amyloid deposition and gliosis but also improvement in cognitive impairment. Inquiring, however, on the effects of EP67 in an already heavily burdened animal, thus representing a more realistic scenario, we treated 6-month-old 5XFAD mice for a period of 14 weeks. We recorded a significant decrease in both fibrillar and pre-fibrillar ß-amyloid as well as remarkable amelioration of cognitive impairment. Following proteomic analysis and pathway association, we postulate that these events are triggered through the upregulation of ß-adrenergic and GABAergic signaling. In summary, our results reveal how inflammatory responses can be employed in inducing tangible phenotype improvements even in advanced stages of AD.

Omega-3 fatty acids promote neuroprotection, decreased apoptosis and reduced glial cell activation in the retina of a mouse model of OPA1-related autosomal dominant optic atrophy.

The purpose of this study was to evaluate the neuroprotective effects of omega-3 polyunsaturated fatty acid (ω3-PUFA) supplementation in a mouse model of OPA1-associated autosomal dominant optic atrophy (ADOA). The blood level of arachidonic acid (AA) and eicosapentaenoic acid (EPA) served to adjust the treatment dosage (AA/EPA = 1.0-1.5). Eight-month-old mice were allocated to four groups (n = 20/group): the ω3-PUFA-treated Opa1enu/+, untreated Opa1enu/+, ω3-PUFA-treated wild-type and untreated wild-type groups. Treated mice received the ω3-PUFAs, EPA and docosahexaenoic acid (DHA; 5:1 ratio) by daily gavage for 4 months based on the measured AA/EPA ratio. Blood, retina and optic nerve (ON) fatty acid levels were determined by gas chromatography, and the retina and ON were histologically examined. Western blotting and/or immunohistochemistry was performed to analyse retinal mediators involved in Opa1-mutation-mediated apoptosis, inflammation and oxidative stress. Increased EPA and reduced AA levels were primarily observed predominantly in the blood and retinal tissues, and a similarly high EPA level tended to be observed in the ONs of ω3-PUFA-treated mice. Retinal ganglion cell and ON axonal densities were higher in both mouse strains upon ω3-PUFA treatment than in the corresponding untreated groups. Caspase-3 expression analysis showed fewer apoptotic retinal cells in both groups of treated mice. Decreases in inflammatory microglia and astrocytes activation and proapoptotic Bcl-2-associated X protein (Bax) expression were noted in the treated groups, with no difference in the antioxidant superoxide dismutase-2 expression. ω3-PUFA supplementation had neuroprotective effects on the retinas of Opa1enu/+ and wild-type mice via blockade of microglia and astrocytes activation and suppression of Bax and caspase-3. Our findings indicated that inhibition of oxidative stress may not be involved in ω3-PUFA-mediated neuroprotection. These novel findings support the use of ω3-PUFAs as a beneficial therapy in the occurrence of ADOA, posing the basis for future clinical trials to confirm these observations.

C5aR agonist enhances phagocytosis of fibrillar and non-fibrillar Aß amyloid and preserves memory in a mouse model of familial Alzheimer's disease.

According to the amyloid hypothesis of Alzheimer's disease (AD) the deposition of prefibrillar and fibrillar Aß peptide sets off the pathogenic cascades of neuroinflammation and neurodegeneration that lead to synaptic and neuronal loss resulting in cognitive decline. Various approaches to reduce amyloid load by reducing production of the Aß peptide or enhancing amyloid clearance by primary or secondary immunization have not proven successful in clinical trials. Interfering with the normal function of secretases and suboptimal timing of Aß peptide removal have been put forward as possible explanations. Complement, an innate component of the immune system, has been found to modulate disease pathology and in particular neuronal loss in the AD mouse model but its mechanism of action is complex. C1Q has been shown to facilitate phagocytosis of Aß peptide but its Ablation attenuates neuroinflammation. Experiments in AD mouse models show that inhibition of complement component C5a reduces amyloid deposition and alleviates neuroinflammation. Phagocytes including microglia, monocytes and neutrophils carry C5a receptors. Here, a widely used mouse model of AD, 5XFAD, was intermittently treated with the oral C5a receptor agonist EP67 and several neuronal and neuroinflammatory markers as well as memory function were assessed. EP67 treatment enhanced phagocytosis, resulting in a significant reduction of both fibrillar and non-fibrillar Aß, reduced astrocytosis and preserved synaptic and neuronal markers as well as memory function. Timely and phasic recruitment of the innate immune system offers a new therapeutic avenue of treating pre-symptomatic Alzheimer disease.

Pharmacological Stimulation of Phagocytosis Enhances Amyloid Plaque Clearance; Evidence from a Transgenic Mouse Model of ATTR Neuropathy.

Hereditary ATTR V30M amyloidosis is a lethal autosomal dominant sensorimotor and autonomic neuropathy caused by deposition of aberrant transthyretin (TTR). Immunohistochemical examination of sural nerve biopsies in patients with amyloidotic neuropathy show co-aggregation of TTR with several proteins; including apolipoprotein E, serum amyloid P and components of the complement cascade. Complement activation and macrophages are increasingly recognized to play a crucial role in amyloidogenesis at the tissue bed level. In the current study we test the effect of two C5a receptor agonists and a C5a receptor antagonist (PMX53) on disease phenotype in ATTR V30M mice. Our results indicate that amyloid deposition was significantly reduced following treatment with the C5a receptor agonists, while treatment with the antagonist resulted in a significant increase of amyloid load. Administration of the C5a receptor agonists triggered increased recruitment of phagocytic cells resulting in clearance of amyloid deposits.

C1q ablation exacerbates amyloid deposition: A study in a transgenic mouse model of ATTRV30M amyloid neuropathy.

ATTRV30M amyloid neuropathy is a lethal autosomal dominant sensorimotor and autonomic neuropathy, caused by deposition of amyloid fibrils composed of aberrant transthyretin (TTR). Ages of onset and penetrance exhibit great variability and genetic factors have been implicated. Complement activation co-localizes with amyloid deposits in amyloidotic neuropathy and is possibly involved in the kinetics of amyloidogenesis. A candidate gene approach has recently identified C1q polymorphisms to correlate with disease onset in a Cypriot cohort of patients with ATTRV30M amyloid neuropathy. In the current study we use a double transgenic mouse model of ATTRV30M amyloid neuropathy in which C1q is ablated to elucidate further a possible modifier role for C1q. Amyloid deposition is found to be increased by 60% in the absence of C1q. Significant up regulation is also recorded in apoptotic and cellular stress markers reflecting extracellular toxicity of pre-fibrillar and fibrillar TTR. Our data further indicate that in the absence of C1q there is marked reduction of macrophages in association with amyloid deposits and thus less effective phagocytosis of TTR.