Notoginsenoside Fc Accelerates Reendothelialization following Vascular Injury in Diabetic Rats by Promoting Endothelial Cell Autophagy

Notoginsenoside Fc alleviates oxidized low-density lipoprotein-induced endothelial cell dysfunction and upregulates PPAR-γ in vitro

BACKGROUND

Deep venous thrombosis (DVT) is a prevalent vascular disease and a major cause of morbidity and mortality worldwide. Notoginsenoside Fc (NFc) is a protopanaxadiol-type saponin that has been shown to have beneficial effects on several disorders. However, its function in DVT is unclear.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to mimic DVT in vitro and treated with NFc to investigate its functions. CCK-8 assay was utilized for measuring cell viability. Western blotting was used for detecting protein levels of proinflammatory cytokines, apoptosis-related markers, and peroxisome proliferator-activated receptor-γ (PPAR-γ). Flow cytometry was performed for cell apoptosis detection. Levels of oxidative stress-related markers were examined by the DCFH-DA method and ELISA. RT-qPCR was utilized for the measurement of PPAR-γ mRNA level.

RESULTS

NFc increased the viability and suppressed inflammation, apoptosis, and oxidative stress in ox-LDL-treated HUVECs. NFc treatment induced upregulation of PPAR-γ in HUVECs.

CONCLUSION

NFc mitigates ox-LDL-induced dysfunction of HUVECs.

Notoginsenoside Fc, a novel renoprotective agent, ameliorates glomerular endothelial cells pyroptosis and mitochondrial dysfunction in diabetic nephropathy through regulating HMGCS2 pathway

BACKGROUND

Diabetic nephropathy (DN) is the primary cause of end-stage renal disease (ESRD), and the therapeutic strategies for DN are limited. Notoginsenoside Fc (Fc), a novel saponin isolated from Panax Notoginseng (PNG), has been reported to alleviate vascular injury in diabetic rats. However, the protective effects of Fc on DN remain unclear.

PURPOSE

To investigate the beneficial effects and mechanisms of Fc on DN.

METHODS

Db/db mice were treated with 2.5, 5 and 10 mg·kg-1·d-1 of Fc for 8 weeks. High glucose (HG) induced mouse glomerular endothelial cells (GECs) were treated with 2.5, 5 and 10 μM of Fc for 24 h.

RESULTS

Our data found that Fc ameliorated urinary microalbumin level, kidney dysfunction and histopathological damage in diabetic mice. Moreover, Fc alleviated the accumulation of oxidative stress, the collapse of mitochondrial membrane potential and the expression of mitochondrial fission proteins, such as Drp-1 and Fis1, while increased the expression of mitochondrial fusion protein Mfn2. Fc also decreased pyroptosis-related proteins levels, such as TXNIP, NLRP3, cleaved caspase-1, and GSDMD-NT, indicating that Fc ameliorated GECs pyroptosis. In addition, 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) expression was increased in diabetic group, which was partially abrogated by Fc. Our data further proved that knockdown of HMGCS2 could restrain HG-induced GECs mitochondrial dysfunction and pyroptosis. These results indicated that the inhibitory effects of Fc on mitochondrial damage and pyroptosis were associated with the suppression of HMGCS2.

CONCLUSION

Taken together, this study clearly demonstrated that Fc ameliorated GECs pyroptosis and mitochondrial dysfunction partly through regulating HMGCS2 pathway, which might provide a novel drug candidate for DN.

Traditional Chinese medicine and its active substances reduce vascular injury in diabetes via regulating autophagic activity

Due to its high prevalence, poor prognosis, and heavy burden on healthcare costs, diabetic vascular complications have become a significant public health issue. Currently, the molecular and pathophysiological mechanisms underlying diabetes-induced vascular complications remain incompletely understood. Autophagy, a highly conserved process of lysosomal degradation, maintains intracellular homeostasis and energy balance via removing protein aggregates, damaged organelles, and exogenous pathogens. Increasing evidence suggests that dysregulated autophagy may contribute to vascular abnormalities in various types of blood vessels, including both microvessels and large vessels, under diabetic conditions. Traditional Chinese medicine (TCM) possesses the characteristics of "multiple components, multiple targets and multiple pathways," and its safety has been demonstrated, particularly with minimal toxicity in liver and kidney. Thus, TCM has gained increasing attention from researchers. Moreover, recent studies have indicated that Chinese herbal medicine and its active compounds can improve vascular damage in diabetes by regulating autophagy. Based on this background, this review summarizes the classification, occurrence process, and related molecular mechanisms of autophagy, with a focus on discussing the role of autophagy in diabetic vascular damage and the protective effects of TCM and its active compounds through the regulation of autophagy in diabetes. Moreover, we systematically elucidate the autophagic mechanisms by which TCM formulations, individual herbal extracts, and active compounds regulate diabetic vascular damage, thereby providing new candidate drugs for clinical treatment of vascular complications in diabetes. Therefore, further exploration of TCM and its active compounds with autophagy-regulating effects holds significant research value for achieving targeted therapeutic approaches for diabetic vascular complications.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

Optimization of Extraction and Separation Process of Notoginsenoside Fc from Panax notoginseng Leaves

Response surface methodology (RSM) was used to determine the optimal conditions for ultrasound-assisted extraction (UAE) of Notoginsenoside Fc (Fc) from panax notoginseng leaves. The experiment utilized a Box-Behnken design (BBD) and separation conditions were optimized. The optimum extraction conditions were as follows: extraction time = 1.5 h, ethanol concentration = 86%, liquid-to-solid ratio = 19:1. The experimentally obtained values were in accordance with the values predicted by the RSM model. We determined that the RSM model was able to successfully simulate the optimal extraction of Fc from the leaves. Further, Fc was enriched from Panax notoginseng through nine macroporous resins, and HPD-100 macroporous resins were selected for preliminary enrichment of Fc due to its economic costs and benefits. Subsequently, octadecyl silane (ODS) column chromatography was used to improve the purity of Fc to over 90% after separation by ODS column chromatography. Fc with a purity greater than 95% can be obtained by recrystallization. This is the first study that has focused on the extraction and enrichment of Fc from Panax notoginseng leaves using macroporous resin combined with ODS column chromatography, which provides the possibility for further application of Fc.

Notoginsenoside Fc ameliorates renal tubular injury and mitochondrial damage in acetaminophen-induced acute kidney injury partly by regulating SIRT3/SOD2 pathway

Introduction

Mitochondria dysfunction is one of the primary causes of tubular injury in acute kidney injury (AKI). Notoginsenoside Fc (Fc), a new saponin isolated from Panax notoginseng, exhibited numerous pharmacological actions. However, the beneficial effects of Fc on renal tubular impairment and mitochondrial dysfunction in AKI have not been fully studied.

Methods

In this study, we established acetaminophen (APAP)-induced AKI model in mice to examine the therapeutic impacts of Fc on AKI.

Results

Our results showed that Fc could decrease the levels of the serum creatinine (Scr), blood urea nitrogen (BUN) and Cystatin C in mice with AKI. Fc also ameliorated renal histopathology, renal tubular cells apoptosis and restored expression of apoptosis-related proteins such as Bax, Bcl-2 and caspase3 (C-caspase3). Additionally, Fc increased the protein expression of SIRT3 and SOD2 in kidneys from mice with AKI. In vitro studies further showed Fc reduced the apoptosis of HK-2 cells exposure to APAP, attenuated the loss of mitochondrial membrane potential and decreased the formation of mitochondrial superoxide. Fc also partly restored the protein expression of Bax, Bcl-2, C-Caspase3, SIRT3, and SOD2 in HK-2 cells exposure to APAP.

Conclusion

In summary, Fc might reduce renal tubular injury and mitochondrial dysfunction in AKI partly through the regulation of SIRT3/SOD2 pathway.

Trimethylamine-N-oxide (TMAO) promotes balloon injury-induced neointimal hyperplasia via upregulating Beclin1 and impairing autophagic flux

BACKGROUND AND AIMS

TMAO is a microbiota-dependent metabolite associated with increased risk of various cardiovascular diseases. However, the relationship between TMAO and vascular injury-related neointimal hyperplasia is unclear. This study aimed to explore whether TMAO promotes neointimal hyperplasia after balloon injury and elucidate the underlying mechanism.

METHODS AND RESULTS

Through hematoxylin and eosin staining and immunohistochemistry staining, we found that supplementary TMAO promoted balloon injury-induced neointimal hyperplasia, while reducing TMAO by antibiotic administration produced the opposite result. TMAO showed limited effect on rat aortic vascular smooth muscle cells (RAOSMCs) proliferation and migration. However, TMAO notably induced dysfunction of rat aortic vascular endothelial cells (RAOECs) in vitro and attenuated reendothelialization of carotid arteries after balloon injury in vivo. Autophagic flux was measured by fluorescent mRFP-GFP-LC3, transmission electron microscopy, and western blot. TMAO impaired autophagic flux, as evidenced by the accumulation of p62 and LC3II and high autophagosome to autolysosome ratios. Furthermore, we confirmed that Beclin1 level increased in TMAO-treated RAOECs and carotid arteries. Knocking down Beclin1 alleviated TMAO-induced autophagic flux impairment and neointimal hyperplasia.

CONCLUSIONS

TMAO promoted neointimal hyperplasia through Beclin1-induced autophagic flux blockage, suggesting that TMAO is a potential target for improvement of vascular remodeling after injury.

Targeting autophagy using saponins as a therapeutic and preventive strategy against human diseases

Autophagy is a ubiquitous mechanism for maintaining cellular homeostasis through the degradation of long-lived proteins, insoluble protein aggregates, and superfluous or damaged organelles. Dysfunctional autophagy is observed in a variety of human diseases. With advanced research into the role that autophagy plays in physiological and pathological conditions, targeting autophagy is becoming a novel tactic for disease management. Saponins are naturally occurring glycosides containing triterpenoids or steroidal sapogenins as aglycones, and some saponins are reported to modulate autophagy. Research suggests that saponins may have therapeutic and preventive efficacy against many autophagy-related diseases. Therefore, this review comprehensively summarizes and discusses the reported saponins that exhibit autophagy regulating activities. In addition, the relevant signaling pathways that the mechanisms involved in regulating autophagy and the targeted diseases were also discussed. By regulating autophagy and related pathways, saponins exhibit bioactivities against cancer, neurodegenerative diseases, atherosclerosis and other cardiac diseases, kidney diseases, liver diseases, acute pancreatitis, and osteoporosis. This review provides an overview of the autophagy-regulating activity of saponins, the underlying mechanisms and potential applications for managing various diseases.

miR145 Regulates the Proliferation and Apoptosis of Rat Vascular Endothelial Cells under Hyperglycemia by Targeting the ANGPT2 Gene and Involving the NFκB Signaling Pathway

PURPOSE

A majority of diabetes mellitus patients with disturbances of glucose metabolism present with vascular complications. This study aimed to explore regulatory mechanisms of miR145 and its potential target gene ANGPT2 on diabetic vasculopathy under hyperglycemia.

METHODS

Based on the fact that miR145 is detected in rat aortic endothelial cells (RAECs) under hyperglycemia, RAECs were transfected with miR145 mimics/inhibitor for further confirmation. RAEC proliferation was detected with CCK8 assays, and cell apoptosis and CD34⁺-cell population with annexinV-PI staining and anti-CD34FITC on flow cytometry, respectively. Then, qPCR and Western blot were applied to detect mRNA and protein expression of ANGPT2 and involved pathway factor NFκB p65. Subsequently, dual luciferase-reporter gene analysis was utilized to verify whether miR145 acted directly upon the 3'UTR of ANGPT2 mRNA.

RESULTS

The ANGPT2 gene was confirmed to be a direct target of miR145. miR145 mimics markedly downregulated the expression of ANGPT2 and NFκB p65, boosted the percentage of the CD34⁺ phenotype, and promoted proliferation and suppressed apoptosis of RAECs under hyperglycemia.

CONCLUSION

miR145 might regulate the viability of RAECs via targeting ANGPT2 and involving NFκB signaling to exert a protective effect on diabetic vasculature.