Preventive effects of arctigenin from Arctium lappa L against LPS-induced neuroinflammation and cognitive impairments in mice

Natural Products and Their Neuroprotective Effects in Degenerative Brain Diseases: A Comprehensive Review

As the global population ages, the incidence of neurodegenerative diseases such as Alzheimer's and Parkinson's is rapidly rising. These diseases present a significant public health challenge, as they severely impair cognitive and motor functions, ultimately leading to a substantial reduction in quality of life and placing a heavy burden on healthcare systems worldwide. Although several therapeutic agents have been developed to manage the symptoms of these diseases, their effectiveness is often limited, and there remains an urgent need for preventive strategies. Growing evidence indicates that bioactive compounds from natural products possess neuroprotective properties through antioxidant and anti-inflammatory effects, modulating key pathways such as phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and brain-derived neurotrophic factor-tropomyosin receptor kinase B-cAMP response element-binding protein (BDNF-TrkB-CREB), which are crucial for neuronal survival. These compounds may also reduce amyloid-beta and tau pathology, as well as enhance cholinergic neurotransmission by inhibiting acetylcholinesterase activity. By targeting oxidative stress, neuroinflammation, and neurodegeneration, natural products offer a promising approach for both prevention and treatment. These findings suggest that natural products may be promising for preventing and treating neurodegenerative diseases. This review aims to explore the pathogenesis of neurodegenerative diseases, the limitations of current therapies, and the potential role of natural products as therapeutic agents.

Anti-inflammatory and DNA Repair Effects of Astragaloside IV on PC12 Cells Damaged by Lipopolysaccharide

OBJECTIVE

This study aimed to establish a neural cell injury model in vitro by stimulating PC12 cells with lipopolysaccharide (LPS) and to examine the effects of astragaloside IV on key targets using high-throughput sequence technology and bioinformatics analyses.

METHODS

PC12 cells in the logarithmic growth phase were treated with LPS at final concentrations of 0.25, 0.5, 0.75, 1, and 1.25 mg/mL for 24 h. Cell morphology was evaluated, and cell survival rates were calculated. A neurocyte inflammatory model was established with LPS treatment, which reached a 50% cell survival rate. PC12 cells were treated with 0.01, 0.1, 1, 10, or 100 µmol/L astragaloside IV for 24 h. The concentration of astragaloside IV that did not affect the cell survival rate was selected as the treatment group for subsequent experiments. NOS activity was detected by colorimetry; the expression levels of ERCC2, XRCC4, XRCC2, TNF-α, IL-1β, TLR4, NOS and COX-2 mRNA and protein were detected by RT-qPCR and Western blotting. The differentially expressed genes (DEGs) between the groups were screened using a second-generation sequence (fold change>2, P<0.05) with the following KEGG enrichment analysis, RT-qPCR and Western blotting were used to detect the mRNA and protein expression of DEGs related to the IL-17 pathway in different groups of PC12 cells.

RESULTS

The viability of PC12 cells was not altered by treatment with 0.01, 0.1, or 1 µmol/L astragaloside IV for 24 h (P>0.05). However, after treatment with 0.5, 0.75, 1, or 1.25 mg/mL LPS for 24 h, the viability steadily decreased (P<0.01). The mRNA and protein expression levels of ERCC2, XRCC4, XRCC2, TNF-α, IL-1β, TLR4, NOS, and COX-2 were significantly increased after PC12 cells were treated with 1 mg/mL LPS for 24 h (P<0.01); however, these changes were reversed when PC12 cells were pretreated with 0.01, 0.1, or 1 µmol/L astragaloside IV in PC12 cells and then treated with 1 mg/mL LPS for 24 h (P<0.05). Second-generation sequencing revealed that 1026 genes were upregulated, while 1287 genes were downregulated. The DEGs were associated with autophagy, TNF-α, interleukin-17, MAPK, P53, Toll-like receptor, and NOD-like receptor signaling pathways. Furthermore, PC12 cells treated with a 1 mg/mL LPS for 24 h exhibited increased mRNA and protein expression of CCL2, CCL11, CCL7, MMP3, and MMP10, which are associated with the IL-17 pathway. RT-qPCR and Western blotting analyses confirmed that the DEGs listed above corresponded to the sequence assay results.

CONCLUSION

LPS can damage PC12 cells and cause inflammatory reactions in nerve cells and DNA damage. astragaloside IV plays an anti-inflammatory and DNA damage protective role and inhibits the IL-17 signaling pathway to exert a neuroprotective effect in vitro.

GPX4 degradation contributes to fluoride-induced neuronal ferroptosis and cognitive impairment via mtROS-chaperone-mediated autophagy

Ferroptosis is a newly recognized type of programmed cell death that is implicated in the pathophysiological process of neurological disorders. Our previous studies have revealed that exposure to high concentrations of fluoride for long periods of time induces hippocampal neural injury and cognitive deficits. However, whether ferroptosis is involved in fluoride-induced neuronal death and the underlying mechanism remain unknown. In this study, the results indicated that exposure to high fluoride triggered ferroptosis in SH-SY5Y cells and in the hippocampus of mice. Fluoride exposure accelerated the lysosomal degradation of GPX4 and led to neuronal ferroptosis, while GPX4 overexpression protected SH-SY5Y cells against fluoride-induced neurotoxicity. Intriguingly, the enhanced chaperone-mediated autophagy (CMA) induced by fluoride stimulation was responsible for GPX4 degradation because the inhibition of CMA activity by LAMP2A knockdown effectively prevented fluoride-induced GPX4 loss. Furthermore, mitochondrial ROS (mtROS) accumulation caused by fluoride contributed to CMA activation-mediated GPX4 degradation and subsequent neuronal ferroptosis. Notably, the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) or the ROS scavenger N-acetyl-L-cysteine (NAC) alleviated fluoride-evoked hippocampal neuronal death and synaptic injury as well as cognitive deficits in mice. The present studies indicates that ferroptosis is a novel mechanism of fluoride-induced neurotoxicity and that chronic fluoride exposure facilitates GPX4 degradation via mtROS chaperone-mediated autophagy, leading to neuronal ferroptosis and cognitive impairment.

Sleep deprivation aggravates lipopolysaccharide-induced anxiety, depression and cognitive impairment: The role of pro-inflammatory cytokines and synaptic plasticity-associated proteins

Growing evidence indicates that neuroinflammation plays a critical role in anxiety, depression, and cognitive impairment. Sleep loss disrupts the host's immune balance and increases neuroinflammation. This study explored whether chronic sleep deprivation aggravates lipopolysaccharide-induced anxiety, depression, and cognitive impairment and assessed the underlying mechanisms. Lipopolysaccharide (250 μg/kg) was administered to adult mice for 9 days, accompanied with daily intermittent sleep deprivation from 12:00 to 18:00 by using an activity wheel. Anxiety, depression, and cognitive function were evaluated using a task battery consisting of an open field, elevated plus maze, tail suspension, forced swimming, and Morris water maze tests. The levels of pro-inflammatory cytokines and synaptic plasticity-associated proteins were examined by enzyme-linked immunosorbent assay and western blot, respectively. The results showed that lipopolysaccharide increased anxiety- and depression-like behaviors, impaired cognitive function, uprelated interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and decreased brain-derived neurotrophic factor (BDNF), postsynaptic density-95 (PSD-95), and synaptophysin (SYN), which were aggravated by chronic sleep deprivation. These results suggest that chronic sleep deprivation exerted adverse effects on lipopolysaccharide-induced anxiety, depression, and cognitive impairment, which was associated with changes in pro-inflammatory cytokines and synaptic plasticity associated proteins.

NLRP3 inflammasome-mediated pyroptosis involvement in cadmium exposure-induced cognitive deficits via the Sirt3-mtROS axis

Cadmium (Cd), a toxic heavy metal, exerts deleterious effects on neuronal survival and cognitive function. NOD-like receptor 3 (NLRP3) inflammasome-dependent pyroptosis has been linked to Cd-induced cytotoxicity. The current research intended to elucidate the role of NLRP3 inflammasome-mediated pyroptosis in Cd-evoked neuronal death and cognitive impairments and the underlying mechanisms. Exposure to 1 mg/kg Cd for 8 weeks led to hippocampal-dependent cognitive deficits and neural/synaptic damage in mice. NLRP3 inflammasome-related protein expression (NLRP3, ASC, and caspase1 p20) and neuronal pyroptosis were significantly upregulated in Cd-treated hippocampi and SH-SY5Y cells. Moreover, pretreatment with the NLRP3 inhibitor MCC950 mitigated Cd-elicited NLRP3 inflammasome activation and subsequent neuronal pyroptosis in SH-SY5Y cells. Furthermore, exposure to Cd downregulated Sirt3 expression, suppressed SOD2 activity by hyperacetylation, and enhanced mtROS accumulation in vivo and in vitro. Notably, Cd-induced NLRP3 inflammasome-dependent neuronal pyroptosis was attenuated by a mtROS scavenger or Sirt3 overexpression in SH-SY5Y cells. In addition, Cd failed to further suppress SOD activity and activate NLRP3 inflammasome-dependent neuronal pyroptosis in Sirt3 shRNA-treated SH-SY5Y cells. Collectively, our findings indicate that Cd exposure induces neuronal injury and cognitive deficits by activating NLRP3 inflammasome-dependent neuronal pyroptosis and that activation of the NLRP3 inflammasome is partially mediated by the Sirt3-mtROS axis.

BDE-47 flame retardant exposure induces microglial pyroptosis and cognitive deficits by activating the mtROS-NLRP3 axis via Sirt3 downregulation and is salvaged by honokiol

The brominated flame retardant 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) is widely distributed in the environment and poses a certain risk to human health. Studies have reported that oxidative stress is a key mechanism underlying BDE-47-induced neurotoxicity. Mitochondrial reactive oxygen species (mtROS) is a crucial mediator of NLRP3 inflammasome activation, which is involved in cognitive dysfunction induced by environmental toxins. However, the function of the mtROS-NLRP3 inflammasome pathway in BDE-47-elicited cognitive deficits and the underlying mechanisms remain elusive. Our data illustrated that eight weeks of BDE-47 (20 mg/kg) gavage led to cognitive deficits and hippocampal neuronal injury in mice. BDE-47 exposure downregulated Sirt3 expression and decreased the activity and expression level of SOD2, thereby inhibiting mtROS scavenging and activating NLRP3 inflammasome-mediated pyroptosis in the mouse hippocampus and BV-2 cells. In vitro, BDE-47-evoked microglial pyroptosis relied on NLRP3 inflammasome activation. Moreover, a mtROS scavenger (TEMPO) attenuated NLRP3 inflammasome activation and subsequent microglial pyroptosis under BDE-47 stress. Furthermore, Sirt3 overexpression restored the activity and expression of SOD2 and enhanced mtROS scavenging, thereby suppressing NLRP3 inflammasome activation and ameliorating microglial pyroptosis. Notably, honokiol (HKL), a pharmacological agonist of Sirt3, mitigated BDE-47-evoked hippocampal neuronal injury and cognitive impairment by inhibiting mtROS-NLRP3 axis-mediated pyroptosis via Sirt3 upregulation.

The therapeutic potential of arctigenin against multiple human diseases: A mechanistic review

BACKGROUND

Arctigenin (ATG), a dibenzyl butyrolactone lignan compound, is one of the major bioactive components from the medicinal plant Arctium lappa. ATG possesses remarkable therapeutic potential against a wide range of human diseases, such as cancers, immune disorders and chronical diseases. The molecular mechanisms behind the biological effects of ATG have been intensively studied.

PURPOSE

This review aims to systematically summarize the updated knowledge of the proteins and signaling pathways behind the curative property of ATG, and further analyze the potential connections between them.

METHOD

SciFinder, Pubmed, Web of Science and Cochrane Library databases were queried for publications reporting the therapeutic properties of ATG. "Arctigenin", "disease", "cancer", "inflammation", "organ damage", "infection", "toxicity" and "pharmacokinetics" were used as the searching titles.

RESULT

625 publications were identified and 95 met the inclusion criteria and exclusion criteria. 42 studies described the molecular mechanisms implicated in ATG treatments. Several proteins including phosphodiesterase subtype 4D (PDE4D), estrogen receptor (ER) β, protein phosphatase 2A (PP2A), phosphoinositide 3-kinase (PI3K) and transmembrane protein 16A (TMEM16A) are targeted by ATG in different settings. The frequently described signaling pathways are TLR4/NF-κB, PI3K/AKT/mTOR, AMP-activated protein kinase (AMPK) and nuclear factor erythroid 2-related factor 2 (Nrf-2) signalings.

CONCLUSION

Inhibition of PI3K/AKT pathway and activation of AMPK signaling play the pivotal roles in the therapeutic effects of ATG. PI3K/AKT and AMPK signaling widely link to other signaling pathways, modulating various biological processes such as anti-inflammation, anti-oxidative stress, anti-fibrosis, anti-ER stress, anti-steatosis and pro-apoptosis, which constitute the curative mechanisms of ATG against multiple human diseases.

Lipopolysaccharide-Induced Model of Neuroinflammation: Mechanisms of Action, Research Application and Future Directions for Its Use

Despite advances in antimicrobial and anti-inflammatory therapies, inflammation and its consequences still remain a significant problem in medicine. Acute inflammatory responses are responsible for directly life-threating conditions such as septic shock; on the other hand, chronic inflammation can cause degeneration of body tissues leading to severe impairment of their function. Neuroinflammation is defined as an inflammatory response in the central nervous system involving microglia, astrocytes, and cytokines including chemokines. It is considered an important cause of neurodegerative diseases, such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Lipopolysaccharide (LPS) is a strong immunogenic particle present in the outer membrane of Gram-negative bacteria. It is a major triggering factor for the inflammatory cascade in response to a Gram-negative bacteria infection. The use of LPS as a strong pro-inflammatory agent is a well-known model of inflammation applied in both in vivo and in vitro studies. This review offers a summary of the pathogenesis associated with LPS exposure, especially in the field of neuroinflammation. Moreover, we analyzed different in vivo LPS models utilized in the area of neuroscience. This paper presents recent knowledge and is focused on new insights in the LPS experimental model.