Notoginsenoside R1 Alleviates Oxygen-Glucose Deprivation/Reoxygenation Injury by Suppressing Endoplasmic Reticulum Calcium Release via PLC

Bile acids target mitofusin 2 to differentially regulate innate immunity in physiological versus cholestatic conditions

Systemic metabolites serving as danger-associated molecular patterns play crucial roles in modulating the development, differentiation, and activity of innate immune cells. Yet, it is unclear how innate immune cells detect systemic metabolites for signal transmission. Here, we show that bile acids function as endogenous mitofusin 2 (MFN2) ligands and differentially modulate innate immune response to bacterial infection under cholestatic and physiological conditions. Bile acids at high concentrations promote mitochondrial tethering to the endoplasmic reticulum (ER), leading to calcium overload in the mitochondrion, which activates NLRP3 inflammasome and pyroptosis. By contrast, at physiologically relevant low concentrations, bile acids promote mitochondrial fusion, leading to enhanced oxidative phosphorylation and thereby strengthening infiltrated macrophages mediated phagocytotic clearance of bacteria. These findings support that bile acids, as endogenous activators of MFN2, are vital for tuning innate immune responses against infections, representing a causal link that connects systemic metabolism with mitochondrial dynamics in shaping innate immunity.

Inhibition of GluN2B pathway is involved in the neuroprotective effect of silibinin on streptozotocin-induced Alzheimer's disease models

BACKGROUND

Over-activation of N-methyl-D-aspartate receptors (NMDARs) is involved in sporadic Alzheimer's disease. Silibinin, a natural flavonoid gained from the seeds of Silybum marianum, exerts neuroprotective effects on sporadic AD models, but its impacts on NMDARs remain unknown.

PURPOSE

To study silibinin's regulatory effects on NMDARs pathway in sporadic AD models.

METHODS

MTT assay, western blotting, confocal microscopy, flow cytometry, RT-PCR, and siRNA transfection etc. were used for cellular and molecular studies. The direct interactions between silibinin and NMDAR subunits were evaluated by computational molecular docking, drug affinity responsive target stability (DARTS) assay and cellular thermal shift assay (CETSA). Y maze test, novel objects recognition test and Morris water maze test were conducted to examine the learning and memory ability of rats.

RESULTS

An in vitro AD model was established by treating HT22 murine hippocampal neurons with streptozotocin (STZ), as evidenced by the amyloid β (Aβ) deposition and hyperphosphorylation of tau proteins. Silibinin shows protection of neurons against STZ-induced cell damage. It is noteworthy that STZ-induced cellular calcium influx is inhibited by silibinin-treatment, indicating the possible modulation of calcium channels. Studies on NMDARs, the most widely distributed calcium channel, by using molecular docking, DARTS and CESTA, reveal that the GluN2B subunit, but not GluN2A, is the potential target of silibinin. Further studies using the pharmacological agonist (NMDA) and the GluN2B-specific inhibitor (Ifenprodil) or siRNA, indicate that the protection by silibinin treatment from STZ-induced cytotoxicity is medicated through interference with GluN2B-containing NMDARs, followed by the upregulation of CaMKIIα/ BDNF/ TrkB signaling pathway and improved levels of synaptic proteins (SYP and PSD-95). The results in vivo using rats intracerebroventricularly injected with STZ (ICV-STZ), a well-established sporadic AD model, confirm that silibinin improves learning and memory ability in association with modulation of the GluN2B/CaMKIIα/ BDNF/TrkB signaling pathway.

CONCLUSION

Inhibiting over-activation of GluN2B-containing NMDARs is involved in the neuroprotective effect of silibinin on STZ-induced sporadic AD models.

Components of Salvia miltiorrhiza and Panax notoginseng Protect Pericytes Against OGD/R-Induced Injury via Regulating the PI3K/AKT/mTOR and JNK/ERK/P38 Signaling Pathways

Salvia miltiorrhiza (SAL) and Panax notoginseng (PNS) are widely used in treating of ischemic stroke. However, it is unknown which components of SAL and PNS protect brain microvascular pericytes after an ischemic stroke. We evaluated the protective effects and mechanisms of SAL and PNS components in pericytes subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pericytes were subjected to OGD/R. Cell Counting Kit-8 (CCK-8) was used to evaluate cell viability. ROS and SOD kits were used to detect oxidative stress. Flow cytometry was performed to analyze cell apoptosis. To evaluate cell migration, a scratch assay was performed. Expression of cleaved caspase-3, Bcl-2, Bax, VEGF, Ang-1, PDGFR-β, PI3K/AKT/mTOR, and JNK/ERK/P38 signaling pathways were identified using western blot. The results revealed that salvianolic acid B (Sal B), salvianolic acid D (Sal D), notoginsenoside R1 (R1), ginsenoside Rb1 (Rb1), and ginsenoside Rg1 (Rg1) increased the cell viability of pericytes subjected to OGD/R, reduced the level of ROS, and increased the expression of SOD. The components reduced cell apoptosis, increased the protein level of Bcl-2/Bax, reduced the level of cleaved caspase-3/caspase-3, increased cell migration, and enhanced the levels of Ang-1, PDGFR-β, and VEGF. The components could activate PI3K/AKT/mTOR pathway while inhibiting the JNK/ERK/P38 pathway. Studies found that Sal B, Sal D, R1, Rb1, and Rg1 inhibited oxidative stress and apoptosis while increasing the release of pro-angiogenic regulators of pericytes related to the PI3K/AKT/mTOR and JNK/ERK/P38 signaling pathways. This provides a potential foundation for developing monomeric drugs for treating ischemic stroke.

CaMKIIα Signaling Is Required for the Neuroprotective Effects of Dl-3-n-Butylphthalide in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of neurodegenerative disease and most anti-AD drugs have failed in clinical trials; hence, it is urgent to find potentially effective drugs against AD. DL-3-n-butylphthalide (NBP) is a compound extracted from celery seed and is a multiple-target drug. Several studies have demonstrated the neuroprotective effects of NBP on cognitive impairment, but the mechanisms of NBP remains relatively unexplored. In this study, we found that NBP could alleviated the increase of intracellular Ca²⁺ and reversed down-regulation of Ca²⁺/calmodulin-dependent protein kinase alpha (CaMKIIα) signaling and rescued neuronal apoptosis in SH-SY5Y cells treated by Aβ oligomers. However, these neuroprotective effects of NBP on neuronal damage and CaMKIIα signaling were abolished when CaMKIIα expression was knocked down or its activity was inhibited. Thus, our findings suggested that CaMKIIα signaling was required for the neuroprotective effects of NBP in AD and provided an improved basis for elucidating the mechanism and treatment of NBP in AD.

The diverse roles of TMEM16A Ca2+-activated Cl- channels in inflammation

Background

Transmembrane protein 16A (TMEM16A) Ca²⁺-activated Cl^- channels have diverse physiological functions, such as epithelial secretion of Cl^- and fluid and sensation of pain. Recent studies have demonstrated that TMEM16A contributes to the pathogenesis of infectious and non-infectious inflammatory diseases. However, the role of TMEM16A in inflammation has not been clearly elucidated.

Aim of review

In this review, we aimed to provide comprehensive information regarding the roles of TMEM16A in inflammation by summarizing the mechanisms underlying TMEM16A expression and activation under inflammatory conditions, in addition to exploring the diverse inflammatory signaling pathways activated by TMEM16A. This review attempts to develop the idea that TMEM16A plays a diverse role in inflammatory processes and contributes to inflammatory diseases in a cellular environment-dependent manner.

Key scientific concepts of review

Multiple inflammatory mediators, including cytokines (e.g., interleukin (IL)-4, IL-13, IL-6), histamine, bradykinin, and ATP/UTP, as well as bacterial and viral infections, promote TMEM16A expression and/or activity under inflammatory conditions. In addition, TMEM16A activates diverse inflammatory signaling pathways, including the IP₃R-mediated Ca²⁺ signaling pathway, the NF-κB signaling pathway, and the ERK signaling pathway, and contributes to the pathogenesis of many inflammatory diseases. These diseases include airway inflammatory diseases, lipopolysaccharide-induced intestinal epithelial barrier dysfunction, acute pancreatitis, and steatohepatitis. TMEM16A also plays multiple roles in inflammatory processes by increasing vascular permeability and leukocyte adhesion, promoting inflammatory cytokine release, and sensing inflammation-induced pain. Furthermore, TMEM16A plays its diverse pathological roles in different inflammatory diseases depending on the disease severity, proliferating status of the cells, and its interacting partners. We herein propose cellular environment-dependent mechanisms that explain the diverse roles of TMEM16A in inflammation.

Pharmic Activation of PKG2 Alleviates Diabetes-Induced Osteoblast Dysfunction by Suppressing PLCβ1-Ca2+-Mediated Endoplasmic Reticulum Stress

As reported in our previous study, cinaciguat can improve implant osseointegration in type 2 diabetes mellitus (T2DM) rats by reactivating type 2 cGMP-dependent protein kinase (PKG2), but the downstream mechanisms remain unclear. In the present study, we investigated the favorable effect of cinaciguat on primary rat osteoblast, which was cultivated on titanium disc under vitro T2DM conditions (25 mM glucose and 200 μM palmitate), and clarified the therapeutic mechanism by proteomic analysis. The results demonstrated that T2DM medium caused significant downregulation of PKG2 and induced obvious osteoblast dysfunction. And overexpression of PKG2 by lentivirus and cinaciguat could promote cell proliferation, adhesion, and differentiation, leading to decreased osteoblasts injury. Besides, proteomic analysis revealed the interaction between PKG2 and phospholipase Cβ1 (PLCβ1) in the cinaciguat addition group, and we further verified that upregulated PKG2 by cinaciguat could inhibit the activation of PLCβ1, then relieve intracellular calcium overload, and suppress endoplasmic reticulum (ER) stress to ameliorate osteoblast functions under T2DM condition. Collectively, these findings provided the first detailed mechanisms responsible for cinaciguat provided a favorable effect on promoting osseointegration in T2DM and demonstrated a new insight that diabetes mellitus-induced the aberrations in PKG2-PLCβ1-Ca²⁺-ER stress pathway was one underlying mechanism for poor osseointegration.

Emodin-Induced Oxidative Inhibition of Mitochondrial Function Assists BiP/IRE1α/CHOP Signaling-Mediated ER-Related Apoptosis

Cassiae Semen is a widely used herbal medicine and a popular edible variety in many dietary or health beverage. Emerging evidence disclosed that improper administration of Cassiae Semen could induce obvious liver injury, which is possibly attributed to emodin, one of the bioactive anthraquinone compounds in Cassiae Semen, which caused hepatotoxicity, but the underlying mechanisms are not completely understood. Hence, the present study firstly explored the possible role of oxidative stress-mediated mitochondrial dysfunction and ER stress in emodin-cause apoptosis of L02 cells, aiming to elaborate possible toxic mechanisms involved in emodin-induced hepatotoxicity. Our results showed that emodin-induced ROS activated ER stress and the UPR via the BiP/IRE1α/CHOP signaling pathway, followed by ER Ca²⁺ release and cytoplasmic Ca²⁺ overloading. At the same time, emodin-caused redox imbalance increased mtROS while decreased MMP and mitochondrial function, resulting in the leaks of mitochondrial-related proapoptotic factors. Interestingly, blocking Ca²⁺ release from ER by 2-APB could inhibit emodin-induced apoptosis of L02, but the restored mitochondrial function did not reduce the apoptosis rates of emodin-treated cells. Besides, tunicamycin (TM) and doxorubicin (DOX) were used to activate ER stress and mitochondrial injury at a dosage where obvious apoptosis was not observed, respectively. We found that cotreatment with TM and DOX significantly induced apoptosis of L02 cells. Thus, all the results indicated that emodin-induced excessive ROS generation and redox imbalance promoted apoptosis, which was mainly associated with BiP/IRE1α/CHOP signaling-mediated ER stress and would be enhanced by oxidative stress-mediated mitochondrial dysfunction. Altogether, this finding has implicated that redox imbalance-mediated ER stress could be an alternative target for the treatment of Cassiae Semen or other medicine-food homologous varieties containing emodin-induced liver injury.

Structure feature and antidepressant-like activity of a novel exopolysaccharide isolated from Marasmius androsaceus fermentation broth

The structure and antidepressant like activity of MEPS2 extracted from Marasmius androsaceus subjected to submerged fermentation was systematically studied. MEPS2 is a pyranoid polysaccharide composed of glucose and arabinose, which have a molar ratio of 0.56:0.08. The molecular weight was 85,944 Da. The NMR spectrum suggested the extracted MEPS2 contained uronic acid, and the glucosyl linkage was in α form, in accordance with the analysis of FT-IR spectrum. MEPS2 can considerably enhance the levels of noradrenalin (NE) and dopamine (DA) by ELISA. In addition, western blotting results indicated that MEPS2 can enhance the expression levels of TH, D2DR, and CAMKII. Furthermore, we found that AMPT, raclopride, and prazosin blocked the immobility and time-reducing effect of MEPS2. Overall, the antidepressant-like effect of MEPS2 may be involved in catecholamine synthesis and release, and TH, D2DR and CAMKII play an important role in this process.

Focus on Notoginsenoside R1 in Metabolism and Prevention Against Human Diseases

Notoginsenoside (NG)-R1 is one of the main bioactive compounds from Panax notoginseng (PN) root, which is well known in the prescription for mediating the micro-circulatory hemostasis in human. In this article, we mainly discuss NG-R1 in metabolism and the biological activities, including cardiovascular protection, neuro-protection, anti-diabetes, liver protection, gastrointestinal protection, lung protection, bone metabolism regulation, renal protection, and anti-cancer. The metabolites produced by deglycosylation of NG-R1 exhibit higher permeability and bioavailability. It has been extensively verified that NG-R1 may ameliorate ischemia-reperfusion (IR)-induced injury in cardiovascular and neuronal systems mainly by upregulating the activity of estrogen receptor α-dependent phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and nuclear factor erythroid-2-related factor 2 (NRF2) pathways and downregulating nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. However, no specific targets for NG-R1 have been identified. Expectedly, NG-R1 has been used as a main bioactive compound in many Traditional Chinese Medicines clinically, such as Xuesaitong, Naodesheng, XueShuanTong, ShenMai, and QSYQ. These suggest that NG-R1 exhibits a significant potency in drug development.

Notoginsenoside R1 protects human keratinocytes HaCaT from LPS-induced inflammatory injury by downregulation of Myd88

Burn injury is a gigantic challenge in public health which brings multiple negative effects to patients both in physical and spiritual aspects. Inflammation plays vital roles in the progression of burn injury, and our study investigated whether notoginsenoside R1 (NGR1) alleviated lipopolysaccharide (LPS)-induced human keratinocyte HaCaT cell inflammatory injury. Inflammatory injury was induced by LPS in HaCaT cells. Stimulated cells were then treated by NGR1 in different concentrations. Cell viability and cell apoptosis were detected by Cell Counting Kit-8 and flow cytometry, respectively. The concentration of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) was measured by enzyme-linked immunosorbent assay (ELISA). The accumulated levels of apoptosis-related proteins (caspase-3 and caspase-9), nuclear factor κB (NF-κB), p38 mitogen-activated protein kinase (p38MAPK) signal pathways–related proteins (p65, IκBα, and p38MAPK), and myeloid differentiation primary response 88 (MyD88) were examined by western blot. Transfection was used to alter the expression of MyD88. We found that LPS stimulated HaCaT cells and induced cell inflammation, evidenced by decreasing cell viability, increasing cell apoptosis, and elevating TNF-α and IL-6 expressions. Then, we found that NGR1 reversed the results by enhancing cell viability, inhibiting cell apoptosis, and reducing TNF-α and IL-6 expressions. In addition, NGR1 decreased the phosphorylation of p65, IκBα, and p38MAPK, which increased by LPS. Moreover, NGR1 negatively regulated the expression of MyD88, and transfection with pMyD88 led to the opposite results with what showed by NGR1 in LPS-stimulated HaCaT cells. To sum up, NGR1 alleviates LPS-induced HaCaT cell inflammatory injury by downregulation of MyD88, as well as inactivation of NF-κB and p38MAPK signal pathways.

Notoginsenoside R1 for Organs Ischemia/Reperfusion Injury: A Preclinical Systematic Review

Notoginsenoside R1 (NGR1) exerts pharmacological actions for a variety of diseases such as myocardial infarction, ischemic stroke, acute renal injury, and intestinal injury. Here, we conducted a preclinical systematic review of NGR1 for ischemia reperfusion (I/R) injury. Eight databases were searched from their inception to February 23rd, 2019; Review Manager 5.3 was applied for data analysis. CAMARADES 10-item checklist and cell 10-item checklist were used to evaluate the methodological quality. Twenty-five studies with 304 animals and 124 cells were selected. Scores of the risk of bias in animal studies ranged from 3 to 8, and the cell studies ranged from 3 to 5. NGR1 had significant effects on decreasing myocardial infarct size in myocardial I/R injury, decreasing cerebral infarction volume and neurologic deficit score in cerebral I/R injury, decreasing serum creatinine in renal I/R injury, and decreasing Park/Chiu score in intestinal I/R injury compared with controls (all P < 0.05 or P < 0.01). The multiple organ protection of NGR1 after I/R injury is mainly through the mechanisms of antioxidant, anti-apoptosis, and anti-inflammatory, promoting angiogenesis and improving energy metabolism. The findings showed the organ protection effect of NGR1 after I/R injury, and NGR1 can potentially become a novel drug candidate for ischemic diseases. Further translation studies are needed.

Notoginsenoside R1 protects human renal proximal tubular epithelial cells from lipopolysaccharide-stimulated inflammatory damage by up-regulation of miR-26a

BACKGROUND

Notoginsenoside R1 (NGR1) is the main saponin isolated from the roots of Panax notoginseng (Burk.) F.H. Chen (Araliaceae). This study explored the protective effects of NGR1 on human renal proximal tubular epithelial cell inflammatory damage caused by lipopolysaccharide (LPS), as well as possible internal molecular mechanisms.

METHODS

Cell viability and apoptosis were assessed using CCK-8 assay and Annexin V-FITC/PI Apoptosis Detection kit, respectively. Reactive oxygen species (ROS) level was tested using DCFH-DA staining. qRT-PCR was used to measure microRNA-26a (miR-26a), interleukin 1β (IL-1β), IL-6 and tumor necrosis factor α (TNF-α) expressions. miRNA transfection was conducted to knock down miR-26a. The protein expression levels of key molecules related to cell apoptosis, inflammatory response and nuclear factor kappa B (NF-κB) pathway were detected using western blotting.

RESULTS

LPS stimulation caused human renal proximal tubular epithelial cell viability reduction, apoptosis and inflammatory cytokines expression. NGR1 treatment protected human renal proximal tubular epithelial cells from LPS-caused viability reduction, ROS level elevation, apoptosis and inflammatory cytokines expression. Mechanistically, NGR1 enhanced miR-26a expression in LPS-treated human renal proximal tubular epithelial cells. Knockdown of miR-26a reversed the protective effect of NGR1 on LPS-treated cells. Besides, NGR1 inactivated NF-κB pathway in LPS-treated human renal proximal tubular epithelial cells via up-regulating miR-26a.

CONCLUSION

NGR1 protected human renal proximal tubular epithelial cells from LPS-caused inflammatory damage at least partially via up-regulating miR-26a and then inactivating NF-κB pathway.