Effects of Bushen-Yizhi formula on age-related inflammation and oxidative stress in senescence-accelerated mice

A novel strategy for bioactive natural products targeting NLRP3 inflammasome in Alzheimer's disease

Alzheimer's disease (AD), the most common type of dementia, is an ageing-related progressive neurodegenerative brain disorder. Extracellular neuritic plaques composed of misfolded amyloid β (Aβ) proteins and intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein are the two classical characteristics of AD. Aβ and tau pathologies induce neurite atrophy and neuronal apoptosis, leading to cognitive, language, and behavioral deficits. For decades, researchers have made great efforts to explore the pathogens and therapeutics of AD; however, its intrinsic mechanism remains unclear and there are still no well-established strategies to restore or even prevent this disease. Therefore, it would be beneficial for the establishment of novel therapeutic strategy to determine the intrinsic molecular mechanism that is interrelated with the initiation and progression of AD. A variety of evidence indicates that neuroinflammation plays a crucial role in the pathogenesis of AD. Nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain-containing protein 3 (NLRP3) is a key inflammasome sensor of cellular stress and infection that is involved in the innate immune system. In response to a wide range of stimuli like Aβ, NLRP3 assembles apoptosis-associated speck-like protein (ASC) and procaspase-1 into an inflammasome complex to induce the caspase-1 mediated secretion of interleukin (IL)-1β/IL-18 in M1 polarized microglia, triggering the pathophysiological changes and cognitive decline of AD. Therefore, targeting NLRP3 inflammasome seems an efficient path for AD treatment via regulating brain immune microenvironment. Furthermore, accumulating evidence indicates that traditional Chinese medicine (TCM) exerts beneficial effects on AD via NLRP3 inflammasome inactivation. In this review, we summarize current reports on the role and activated mechanisms of the NLRP3 inflammasome in the pathogenesis of AD. We also review the natural products for attenuating neuroinflammation by targeting NLRP3 inflammasome activation, which provides useful clues for developing novel AD treatments.

Selected Natural Products in Neuroprotective Strategies for Alzheimer's Disease-A Non-Systematic Review

Neurodegenerative disorders such as Alzheimer’s disease (AD) are distinguished by the irreversible degeneration of central nervous system function and structure. AD is characterized by several different neuropathologies—among others, it interferes with neuropsychiatrical controls and cognitive functions. This disease is the number one neurodegenerative disorder; however, its treatment options are few and, unfortunately, ineffective. In the new strategies devised for AD prevention and treatment, the application of plant-based natural products is especially popular due to lesser side effects associated with their taking. Moreover, their neuroprotective activities target different pathological mechanisms. The current review presents the anti-AD properties of several natural plant substances. The paper throws light on products under in vitro and in vivo trials and compiles information on their mechanism of actions. Knowledge of the properties of such plant compounds and their combinations will surely lead to discovering new potent medicines for the treatment of AD with lesser side effects than the currently available pharmacological proceedings.

Osthole-Loaded Nanoemulsion Enhances Brain Target in the Treatment of Alzheimer's Disease via Intranasal Administration

Osthole (OST) is a natural coumarin compound that exerts multiple pharmacologic effects. However, the poor water solubility and the low oral absorption of OST limit its clinical application for the treatment of neurologic diseases. A suitable preparation needs to be tailored to evade these unfavourable properties of OST. In this study, an OST nanoemulsion (OST-NE) was fabricated according to the pseudoternary phase diagram method, which was generally used to optimize the prescription in light of the solubility of OST in surfactants and cosurfactants. The final composition of OST-NE was 3.6% of ethyl oleate as oil phase, 11.4% of the surfactant (polyethylene glycol ester of 15-hydroxystearic acid: polyoxyethylene 35 castor oil = 1 : 1), 3% of polyethylene glycol 400 as cosurfactant, and 82% of the aqueous phase. The pharmacokinetic study of OST-NE showed that the brain-targeting coefficient of OST was larger by the nasal route than that by the intravenous route. Moreover, OST-NE inhibited cell death, decreased the apoptosis-related proteins (Bax and caspase-3), and enhanced the activity of antioxidant enzymes (superoxide dismutase and glutathione) in L-glutamate-induced SH-SY5Y cells. OST-NE improved the spatial memory ability, increased the acetylcholine content in the cerebral cortex, and decreased the activity of acetylcholinesterase in the hippocampus of Alzheimer's disease model mice. In conclusion, this study indicates that the bioavailability of OST was improved by using the OST-NE via the nasal route. A low dose of OST-NE maintained the neuroprotective effects of OST, such as inhibiting apoptosis and oxidative stress and regulating the cholinergic system. Therefore, OST-NE can be used as a possible alternative to improve its bioavailability in the prevention and treatment of Alzheimer's disease.

High Levels of β-Amyloid, Tau, and Phospho-Tau in Red Blood Cells as Biomarkers of Neuropathology in Senescence-Accelerated Mouse

Alzheimer's Disease (AD) is the most common Neurodegenerative Disease (ND), primarily characterised by neuroinflammation, neuronal plaques of β-amyloid (Aβ), and neurofibrillary tangles of hyperphosphorylated tau. α-Synuclein (α-syn) and its heteroaggregates with Aβ and tau have been recently included among the neuropathological elements of NDs. These pathological traits are not restricted to the brain, but they reach peripheral fluids as well. In this sense, Red Blood Cells (RBCs) are emerging as a good model to investigate the biochemical alterations of aging and NDs. Herein, the levels of homo- and heteroaggregates of ND-related proteins were analysed at different stages of disease progression. In particular, a validated animal model of AD, the SAMP8 (Senescence-Accelerated Mouse-Prone) and its control strain SAMR1 (Senescence-Accelerated Mouse-Resistant) were used in parallel experiments. The levels of the aforementioned proteins and of the inflammatory marker interleukin-1β (IL-1β) were examined in both brain and RBCs of SAMP8 and SAMR1 at 6 and 8 months. Brain Aβ, tau, and phospho-tau (p-tau) were higher in SAMP8 mice than in control mice and increased with AD progression. Similar accumulation kinetics were found in RBCs, even if slower. By contrast, α-syn and its heterocomplexes (α-syn-Aβ and α-syn-tau) displayed different accumulation kinetics between brain tissue and RBCs. Both brain and peripheral IL-1β levels were higher in SAMP8 mice, but increased sooner in RBCs, suggesting that inflammation might initiate at a peripheral level before affecting the brain. In conclusion, these results confirm RBCs as a valuable model for monitoring neurodegeneration, suggesting peripheral Aβ, tau, and p-tau as potential early biomarkers of AD.

Bushen-Yizhi Formula Alleviates Neuroinflammation via Inhibiting NLRP3 Inflammasome Activation in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD), the second most common neurodegenerative disease, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra. Although the molecular mechanisms underlying dopaminergic neuronal degeneration in PD remain unclear, neuroinflammation is considered as the vital mediator in the pathogenesis and progression of PD. Bushen-Yizhi Formula (BSYZ), a traditional Chinese medicine, has been demonstrated to exert antineuroinflammation in our previous studies. However, it remains unclear whether BSYZ is effective for PD. Here, we sought to assess the neuroprotective effects and explore the underlying mechanisms of BSYZ in a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine- (MPTP-) induced mouse model of PD. Our results indicate that BSYZ significantly alleviates the motor impairments and dopaminergic neuron degeneration of MPTP-treated mice. Furthermore, BSYZ remarkably attenuates microglia activation, inhibits NLPR3 activation, and decreases the levels of inflammatory cytokines in MPTP-induced mouse brain. Also, BSYZ inhibits NLRP3 activation and interleukin-1β production of the 1-methyl-4-phenyl-pyridinium (MPP⁺) stimulated BV-2 microglia cells. Taken together, our results indicate that BSYZ alleviates MPTP-induced neuroinflammation probably via inhibiting NLRP3 inflammasome activation in microglia. Collectively, BSYZ may be a potential therapeutic agent for PD and the related neurodegeneration diseases.