Ginkgolide K promotes the clearance of A53T mutation alpha-synuclein in SH-SY5Y cells

HC070, a Transient Receptor Potential Canonical 5 (TRPC5) Channels Inhibitor Ameliorated α-synuclein Preformed Fibrils-Induced Parkinson's Disease: A Neurobehavioural and Mechanistic Study

Alpha-synuclein pathology is a characteristic feature of Parkinson's disease (PD) and related synucleinopathies. As a result, reducing alpha-synuclein pathology is one of the mechanisms being looked at for the development of newer agents which target these diseases. In the present study, we investigated the potential of HC070, a transient receptor potential canonical 5 (TRPC5) channel inhibitor in reducing alpha-synuclein pathology in PD. TRPC5 channels are activated in response to oxidative stress and mediators of apoptosis (calpain), the processes are also closely linked to alpha-synuclein toxicity. Using exposure of alpha synuclein-preformed fibrils to the Sprague Dawley rats and SH-SY5Y cells, we induced PD in in vitro and in vivo model systems. It was followed by the estimation of behavioural deficits, molecular parameters and biochemical estimations. Results of our experiments revealed that animals treated intraperitoneally with HC070 exhibited reduced alpha-synuclein levels accompanied by improvement in tyrosine hydroxylase levels, mitochondrial health and reduction in oxidative stress and calpain signalling. Furthermore, HC070 administration also caused a reduction in the TRPC5 levels along with improvement seen in motor and cognitive deficits. Similar protection was observed with HC070 in SH-SY5Y cells exposed to alpha-synuclein PFF. Overall, our study demonstrates the novel role of inhibition of TRPC5 channels in the reversal of alpha-synuclein toxicity and associated PD pathology.

Autosomal dominant Parkinson's disease caused by the recently identified LRRK2 N1437D mutation in a Chinese family: Clinical features, imaging findings, and functional impact

INTRODUCTION

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of autosomal dominantly inherited Parkinson's disease (PD). Recently, a novel pathogenic variant (N1437D; c.4309A > G; NM_98578) in the LRRK2 gene has been identified in three Chinese families with PD. In this study, we describe a Chinese family with autosomal dominant PD that segregated with the N1437D mutation. A detailed clinical and neuroimaging characterization of the affected family members is reported. We also sought to investigate the functional mechanisms by which the detected mutation could cause PD.

METHODS

We characterized the clinical and imaging phenotype of a Chinese pedigree with autosomal dominant PD. We searched for a disease-causing mutation by targeted sequencing and multiple ligation-dependent probe amplification. The functional impact of the mutation was investigated in terms of LRRK2 kinase activity, guanosine triphosphate (GTP) binding, and guanosine triphosphatase (GTPase) activity.

RESULTS

The disease was found to co-segregate with the LRRK2 N1437D mutation. Patients in the pedigree exhibited typical parkinsonism (age at onset: 54.0 ± 5.9 years). One affected family member - who had evidence of abnormal tau accumulation in the occipital lobe on tau PET imaging - developed PD dementia at follow-up. The mutation markedly increased LRRK2 kinase activity and promoted GTP binding, without affecting GTPase activity.

CONCLUSIONS

This study describes the functional impact of a recently identified LRRK2 mutation, N1437D, that causes autosomal dominant PD in the Chinese population. Further research is necessary to investigate the contribution of this mutation to PD in multiple Asian populations.

Terpenoid natural products exert neuroprotection via the PI3K/Akt pathway

PI3K/Akt, an essential signaling pathway widely present in cells, has been shown to be relevant to neurological disorders. As an important class of natural products, terpenoids exist in large numbers and have diverse backbones, so they have a great chance to be identified as neuroprotective agents. In this review, we described and summarized recent research for a range of terpenoid natural products associated with the PI3K/Akt pathway by classifying their basic chemical structures of the terpenes, identified by electronic searches on PubMed, Web of Science for research, and Google Scholar websites. Only articles published in English were included. Our discussion here concerned 16 natural terpenoids and their mechanisms of action, the associated diseases, and the methods of experimentation used. We also reviewed the discovery of their chemical structures and their derivatives, and some compounds have been concluded for their structure–activity relationships (SAR). As a result, terpenoids are excellent candidates for research as natural neuroprotective agents, and our content will provide a stepping stone for further research into these natural products. It may be possible for more terpenoids to serve as neuroprotective agents in the future.

Uncovering the pharmacology of Ginkgo biloba folium in the cell-type-specific targets of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease with a fast-growing prevalence. Developing disease-modifying therapies for PD remains an enormous challenge. Current drug treatment will lose efficacy and bring about severe side effects as the disease progresses. Extracts from Ginkgo biloba folium (GBE) have been shown neuroprotective in PD models. However, the complex GBE extracts intertwingled with complicated PD targets hinder further drug development. In this study, we have pioneered using single-nuclei RNA sequencing data in network pharmacology analysis. Furthermore, high-throughput screening for potent drug-target interaction (DTI) was conducted with a deep learning algorithm, DeepPurpose. The strongest DTIs between ginkgolides and MAPK14 were further validated by molecular docking. This work should help advance the network pharmacology analysis procedure to tackle the limitation of conventional research. Meanwhile, these results should contribute to a better understanding of the complicated mechanisms of GBE in treating PD and lay the theoretical ground for future drug development in PD.

Non-polyphenolic natural inhibitors of amyloid aggregation

Protein misfolding diseases (PMDs) are chronic and progressive, with no effective therapy so far. Aggregation and misfolding of amyloidogenic proteins are closely associated with the onset and progression of PMDs, such as amyloid-β (Aβ) in Alzheimer's disease, α-Synuclein (α-Syn) in Parkinson's disease and human islet amyloid polypeptide (hIAPP) in type 2 diabetes. Inhibiting toxic aggregation of amyloidogenic proteins is regarded as a promising therapeutic approach in PMDs. The past decade has witnessed the rapid progresses of this field, dozens of inhibitors have been screened and verified in vitro and in vivo, demonstrating inhibitory effects against the aggregation and misfolding of amyloidogenic proteins, together with beneficial effects. Natural products are major sources of small molecule amyloid inhibitors, a number of natural derived compounds have been identified with great bioactivities and translational prospects. Here, we review the non-polyphenolic natural inhibitors that potentially applicable for PMDs treatment, along with their working mechanisms. Future directions are proposed for the development and clinical applications of these inhibitors.

Ginkgolide K supports remyelination via induction of astrocytic IGF/PI3K/Nrf2 axis

Although several therapies are approved, none promote re-myelination in multiple sclerosis (MS) patients, limiting their ability for sustained recovery. Thus, treatment development in MS has the opportunity to tackle the challenges, including experimental therapies targeting neuroprotection and re-myelination. Here, we provide a novel therapeutic target for Ginkgolide K (GK) that is now becoming a very critical natural compound to treat demyelination and neurodegeneration. GK improves behavioral dysfunction and demyelination in cuprizone (CPZ) model, followed by the migration and enrichment of astrocytes in the corpus callosum. Both in vitro and in vivo experiments demonstrates that GK triggers the upregulation of Nrf2/HO-1 in astrocytes and inhibition of p-NF-kB/p65, which is associated with the outcome of anti-inflammation and anti-oxidation by suppressing the production of IL-6 and TNFα as well as nitric oxide and iNOS in astrocytes. Further findings suggest that IGF/PI3K, but not BDNF, was induced in the corpus callosum after GK treatment, revealing that Nrf2 activation inhibited caspase-3 and apoptosis in O4+ oligodendrocytes possibly through IGF/PI3K signaling molecules. Since the current immunomodulatory therapies for MS have failed to prevent patients from entering the progressive phase of the disease, thus targeting Nrf2 in astrocytes with GK would be an ideal strategy for myelin protection and regeneration.

The therapeutic potential of ginkgolide K in experimental autoimmune encephalomyelitis via peripheral immunomodulation

Multiple sclerosis is a T cell-mediated inflammatory, demyelinating disease of the central nervous system, accompanied by neuronal degeneration. Based on the anti-inflammatory effects of Ginkgolide K (GK), a platelet activating factor antagonist, we explored the possible application of GK in the treatment of MS. The results showed that GK effectively ameliorated the severity of experimental autoimmune encephalomyelitis. The intervention of GK inhibited the infiltration of inflammatory cells and demyelination in the spinal cord. At the same time, the expression of the inflammation-related molecules TLR4, NF-κB, and COX2 in the spinal cord was significantly lower in the GK-treated mice, indicating that GK intervention can inhibit the inflammatory microenvironment of the spinal cord in EAE mice. In mouse spleen lymphocytes, GK increased the proportion of regulatory T cells (Treg) and reduced the proportion of T helper 17 cells (Th17), modifying the imbalance between Th17/Treg cells. Additionally, GK shifted macrophage/microglia polarization from M1 to M2 cell type. Importantly, GK inhibited the expression of chemotactic molecules CCL-2, CCL-3 and CCL-5, thereby limiting the migration of inflammatory cells to the spinal cord. Our results provide the possibility that GK may be a promising naturally small molecule compound for the future treatment of MS.

Antioxidant effects of ginkgolides and bilobalide against cerebral ischemia injury by activating the Akt/Nrf2 pathway in vitro and in vivo

Ginkgolide terpenoid lactones, including ginkgolides and bilobalide, are two crucial bioactive constituents of extract of Ginkgo biloba (EGb) which was used in the treatment of cardiovascular and cerebrovascular diseases. The aims of this study were to investigate the antioxidant effects and mechanism of ginkgolides (ginkgolide A (GA), ginkgolide B (GB), ginkgolide K (GK)) and bilobalide (BB) against oxidative stress induced by transient focal cerebral ischemia. In vitro, SH-SY5Y cells were exposed to oxygen-glucose deprivation (OGD) for 4 h followed by reoxygenation with ginkgolides and BB treatments for 6 h, and then cell viability, superoxide dismutase (SOD), and ROS were respectively detected using kit. Western blot was used to confirm the protein levels of hemeoxygenase-1 (HO-1), quinone oxidoreductase l (Nqo1), Akt, phosphorylated Akt (p-Akt), nuclear factor-E2-related factor2 (Nrf2), and phosphorylated Nrf2 (p-Nrf2). GB combined with different concentrations of LY294002 (PI3K inhibitor) were administrated to SH-SY5Y cells for 1 h after OGD, and then p-Akt and p-Nrf2 levels were detected by western blot. In vivo, 2 h of middle cerebral artery occlusion (MCAO) model was established, followed with reperfusion and GB treatments for 24 and 72 h. The infarct volume ratios were confirmed by TTC staining. The protein levels of HO-1, Nqo1, SOD1, Akt, p-Akt, Nrf2, and p-Nrf2 were detected using western blot and immunohistochemistry (IHC). Experimental data in vitro confirm that GA, GB, GK, and BB resulted in significant decrease of ROS and increase of SOD activities and protein levels of HO-1 and Nqo1; however, GB group had a significant advantage in comparison with the GA and GK groups. Moreover, after ginkgolides and BB treatments, p-Akt and p-Nrf2 were significantly upregulated, which could be inhibited by LY294002 in a dose-dependent manner, meanwhile, GB exhibited more effective than GA and GK. In vivo, TTC staining indicated that the infarct volume ratios in MCAO rats were dramatically decreased by GB in a dose-dependent manner. Furthermore, GB significantly upregulated the protein levels of HO-1, Nqo1, SOD, p-Akt, p-Nrf2, and Nrf2. In conclusion, GA, GB, GK, and BB significantly inhibited oxidative stress damage caused by cerebral ischemia reperfusion. Compared with GA, GK, and BB, GB exerts the strongest antioxidant stress effects against ischemic stroke. Moreover, ginkgolides and BB upregulated the levels of antioxidant proteins through mediating the Akt/Nrf2 signaling pathway to protect neurons from oxidative stress injury.

Understanding multifactorial architecture of Parkinson's disease: pathophysiology to management

Parkinson's disease (PD) is the second most common multifactorial neurodegenerative disorder affecting 3% of population during elder age. The loss of substantia nigra, pars compacta (SNpc) neurons and deficiency of striatal dopaminergic neurons produces stables motor deficient. Further, increase alpha-synuclein accumulation, mitochondrial dysfunction, oxidative stress, excitotoxicity, and neuroinflammation plays a crucial role in the pathogenesis of PD. Alpha-synuclein protein encodes for SNCA gene and disturbs the normal physiological neuronal signaling via altering mitochondrial homeostasis. The level of α-synuclein is increased in both normal aging and PD brain to a greater extent and secondly reduced clearance results in accumulation of Lewy bodies (LB). Emerging evidences indicate that mitochondrial dysfunction might be a common cause but pathological insult through protein misfolding, aggregation, and accumulation leads to neuronal apoptosis. The observation supporting that expression of DJ-1, LLRK2, PARKIN, PINK1, and excessive excitotoxicity mediated by dysbalance between GABA and glutamate reduced mitochondrial functioning and increased neurotoxicity. Therefore, the present review summarizes the various pathological mechanisms and also explores the therapeutic strategies which could be useful to ameliorate movement disorder like Parkinsonism.