Salvianolic acid A ameliorates renal ischemia/reperfusion injury by activating Akt/mTOR/4EBP1 signaling pathway

Targeting oxidative stress as a preventive and therapeutic approach for cardiovascular disease

Cardiovascular diseases (CVDs) continue to exert a significant impact on global mortality rates, encompassing conditions like pulmonary arterial hypertension (PAH), atherosclerosis (AS), and myocardial infarction (MI). Oxidative stress (OS) plays a crucial role in the pathogenesis and advancement of CVDs, highlighting its significance as a contributing factor. Maintaining an equilibrium between reactive oxygen species (ROS) and antioxidant systems not only aids in mitigating oxidative stress but also confers protective benefits on cardiac health. Herbal monomers can inhibit OS in CVDs by activating multiple signaling pathways, such as increasing the activity of endogenous antioxidant systems and decreasing the level of ROS expression. Given the actions of herbal monomers to significantly protect the normal function of the heart and reduce the damage caused by OS to the organism. Hence, it is imperative to recognize the significance of herbal monomers as prospective therapeutic interventions for mitigating oxidative damage in CVDs. This paper aims to comprehensively review the origins and mechanisms underlying OS, elucidate the intricate association between CVDs and OS, and explore the therapeutic potential of antioxidant treatment utilizing herbal monomers. Furthermore, particular emphasis will be placed on examining the cardioprotective effects of herbal monomers by evaluating their impact on cardiac signaling pathways subsequent to treatment.

Salvianolic Acid A Improves Rat Kidney Injury by Regulating MAPKs and TGF-β1/Smads Signaling Pathways

Salvianolic acid A (SAA) is one of the major components in Salvia miltiorrhiza Bge., with various pharmacological activities, and is likely to be a promising agent for the treatment of kidney diseases. The purpose of this study was to explore the protective effect and mechanisms of SAA on kidney disease. In this study, the improvement effects of SAA (10, 20, 40 mg/kg, i.g.) on kidney injury rats were investigated by detecting the levels of KIM-1, NGAL in serum and UP in the urine of AKI model rats established with gentamicin, as well as the levels of SCr and UREA in serum and IL-6, IL-12, MDA and T-SOD in the kidneys of CKD model rats established with 5/6 nephrectomy. HE and Masson staining were used to observe the histopathological changes in the kidney. Network pharmacology and Western blotting were used to explore the mechanism of SAA in improving kidney injury. The results showed that SAA improved kidney function in kidney injury rats by reducing the kidney index and pathological injury by HE and Masson staining, reducing the levels of KIM-1, NGAL and UP in AKI rats and UREA, SCr and UP in CKD rats, as well as exerting anti-inflammatory and anti-oxidative stress effects by inhibiting the release of IL-6 and IL-12, reducing MDA and increasing T-SOD. Western blotting results showed that SAA significantly reduced the phosphorylation levels of ERK1/2, p38, JNK and smad2/3, and the expression of TLR-4 and smad7. In conclusion, SAA plays a significant role in improving kidney injury in rats and the mechanism may be achieved by regulating the MAPKs and TGF-β1/smads signaling pathways.

Salvianolate ameliorates renal tubular injury through the Keap1/Nrf2/ARE pathway in mouse kidney ischemia-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Acute kidney injury (AKI) is a common clinical disease characterized by rapid loss of renal function. Salvianolate is a prescribed Chinese medicine derived from traditional Chinese medicine Salvia miltiorrhiza bunge that possesses many pharmacological effects, the active components extracted from Salvia miltiorrhiza bunge have been proved to protect ischemia-reperfusion (I/R)-AKI.

AIM OF THE STUDY

This study aims to validate the therapeutic effect of SAL on I/R-AKI, and explore its potential pharmacological mechanism.

MATERIALS AND METHODS

Mice were pretreated with/without salvianolate (10, 30, and 90 mg/kg) before renal ischemia-reperfusion operation. Serum creatinine, BUN, and H&E staining were performed to evaluate renal function. Immunofluorescence analysis was conducted to measure renal tubular injury including inflammatory factors and peroxide level. Apoptosis of the kidney tissues was determined by TUNEL assay. Keap1-Nrf2-ARE and apoptosis signaling pathways were measured by Western blot, RT-PCR, and YO-PRO-1 staining in kidneys or NRK52E cells.

RESULTS

Pretreatment with SAL effectively alleviated renal function and ameliorated epithelial tubular injury, oxidative stress, and inflammatory response. Furthermore, the mechanistic study demonstrated that the SAL exerts anti-apoptotic effects through activation of the Keap1-Nrf2-ARE signaling pathway in renal tubular cells.

CONCLUSION

These findings indicate the therapeutic benefit of salvianolate in the protection of renal injury from ischemia-reperfusion, and strengthen the evidence for the AKI treatment strategy by the anti-oxidative stress response, suggesting that SAL may be a potential agent for the treatment of AKI.

Renal-Protective Effects and Potential Mechanisms of Traditional Chinese Medicine after Ischemia-Reperfusion Injury

Renal ischemia-reperfusion (I/R) injury mainly causes acute kidney injury (AKI) after renal transplantation, trauma, sepsis, and hypovolemic shock. Patients with renal I/R injury are frequently associated with a poor prognosis. Traditional Chinese medicine (TCM) has been used for the prevention and treatment of various diseases in China and other Asian countries for centuries. Many studies have shown the protective effect of TCM on renal I/R injury, due to its diverse bioactive components. The potential mechanisms of TCMs on renal I/R injury include anti-inflammation, antioxidative effect, anti-cell death, downregulation of adhesion molecule expression, regulation of energy metabolism by restoring Na⁺-K⁺-ATPase activity, and mitochondrial fission. This review summarizes the major developments in the effects and underlying mechanisms of TCMs on the renal I/R injury.

Activation of the AMPK-SIRT1 pathway contributes to protective effects of Salvianolic acid A against lipotoxicity in hepatocytes and NAFLD in mice

Background: Salvianolic acid A (Sal A), a natural polyphenol compound extracted from Radix Salvia miltiorrhiza (known as Danshen in China), possesses a variety of potential pharmacological activities. The aim of this study is to determine mechanisms of hepatoprotective effects of Sal A against lipotoxicity both in cultured hepatocytes and in a mouse model of fatty liver disease. Methods: High-fat and high-carbohydrate diet (HFCD)-fed C57BL/6J mice were employed to establish hepatic lipotoxicity in a mouse model. Two doses of Sal A were administered every other day via intraperitoneal injection (20 and 40 mg/kg BW, respectively). After a 10-week intervention, liver injury was detected by immunohistochemical and biochemical analyses. For in vitro studies, we used HepG2, a human hepatoma cell line, and exposed them to palmitic acid to induce lipotoxicity. The protective effects of Sal A on palmitic acid-induced lipotoxicity were examined in Sal A-pretreated HepG2 cells. Results: Sal A treatments attenuated body weight gain, liver injury, and hepatic steatosis in mice exposed to HFCD. Sal A pretreatments ameliorated palmitic acid-induced cell death but did not reverse effects of HFCD- or palmitate-induced activations of JNK, ERK1/2, and PKA. Induction of p38 phosphorylation was significantly reversed by Sal A in HFCD-fed mice but not in palmitate-treated HepG2 cells. However, Sal A rescued hepatic AMP-activated protein kinase (AMPK) suppression and sirtuin 1 (SIRT1) downregulation by both HFCD feeding in mice and exposure to palmitate in HepG2 cells. Sal A dose-dependently up-regulated p-AMPK and SIRT1 protein levels. Importantly, siRNA silencing of either AMPK or SIRT1 gene expression abolished the protective effects of Sal A on lipotoxicity. Moreover, while AMPK silencing blocked Sal A-induced SIRT1, silencing of SIRT1 had no effect on Sal A-triggered AMPK activation, suggesting SIRT1 upregulation by Sal A is mediated by AMPK activation. Conclusion: Our data uncover a novel mechanism for hepatoprotective effects of Sal A against lipotoxicity both in livers from HFCD-fed mice and palmitic acid-treated hepatocytes.

Supramolecular Nanofibers Containing Arginine-Glycine-Aspartate (RGD) Peptides Boost Therapeutic Efficacy of Extracellular Vesicles in Kidney Repair

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC-EVs) have been recognized as a promising cell-free therapy for acute kidney injury (AKI), which avoids safety concerns associated with direct cell engraftment. However, low stability and retention of MSC-EVs have limited their therapeutic efficacy. RGD (Arg-Gly-Asp) peptide binds strongly to integrins, which have been identified on the surface of MSC-EV membranes; yet RGD has not been applied to EV scaffolds to enhance and prolong bioavailability. Here, we developed RGD hydrogels, which we hypothesized could augment MSC-EV efficacy in the treatment of AKI models. In vivo tracking of the labeled EVs revealed that RGD hydrogels increased retention and stability of EVs. Integrin gene knockdown experiments confirmed that EV-hydrogel interaction was mediated by RGD-integrin binding. Upon intrarenal injection into mouse AKI models, EV-RGD hydrogels provided superior rescuing effects to renal function, attenuated histopathological damage, decreased tubular injury, and promoted cell proliferation in early phases of AKI. RGD hydrogels also augmented antifibrotic effects of MSC-EVs in chronic stages. Further analysis revealed that the presence of microRNA let-7a-5p in MSC-EVs served as the mechanism contributing to the reduced cell apoptosis and elevated cell autophagy in AKI. In conclusion, RGD hydrogels facilitated MSC-derived let-7a-5p-containing EVs, improving reparative potential against AKI. This study developed an RGD scaffold to increase the EV integrin-mediated loading and in turn improved therapeutic efficacy in renal repair; therefore this strategy shed light on MSC-EV application as a cell-free treatment for potentiated efficiency.

Therapeutic potential of polyphenols in cardiovascular diseases: Regulation of mTOR signaling pathway

Cardiovascular diseases comprise of non-communicable disorders that involve the heart and/or blood vessels and have become the leading cause of death worldwide with increased prevalence by age. mTOR is a serine/threonine-specific protein kinase which plays a central role in many physiological processes including cardiovascular diseases, and also integrates various proliferative signals, nutrient and energy abundance and stressful situations. mTOR also acts as central regulator during chronic stress, mitochondrial dysfunction and deregulated autophagy which are associated with senescence. Under oxidative stress, mTOR has been reported to exert protective effects regulating apoptosis and autophagy processes and favoring tissue repair. On the other hand, inhibition of mTOR has been suggested to have beneficial effects against atherosclerosis, cardiac hypertrophy and heart failure, and also in extending the lifespan. In this aspect, the use of drugs or natural compounds, which can target mTOR is an interesting approach in order to reduce the number of deaths caused by cardiovascular disease. In the present review, we intend to shed light on the possible effects and molecular mechanism of natural agents like polyphenols via regulating mTOR.

Preventive effects of fraxin on ischemia/reperfusion-induced acute kidney injury in rats

AIM

Kidney ischemia reperfusion (IR) injury is an important health problem resulting in acute kidney failure. The oxidative stress and inflammatory process are the underlying mechanisms of IR injury. It has been purposed in this study to research the possible protective effects of fraxin on kidney injury induced by IR.

MATERIAL AND METHODS

32 Sprague Dawley male rats were divided into 4 groups. The groups were organized as follows; sham, IR, IR + fraxin 10 mg/kg, and IR + 50 mg/kg fraxin groups. Some oxidant, antioxidant and inflammatory parameters were evaluated in kidney tissues removed at the end of our experimental study.

KEY FINDINGS

It was detected that the oxidant and proinflammatory markers increased and antioxidant parameters decreased in IR group but the results significantly reversed in treatment groups compared to IR group. And also, 8-OHdG, NF-κB, HAVCR1 immunopositivities were at severe levels and these results attenuated in IR fraxin + 10 mg/kg, and IR + fraxin 50 mg/kg groups.

SIGNIFICANCE

These presented results have shown that fraxin performed protective effects against kidney injury induced by IR.

Propolis and Its Combination with Boric Acid Protect Against Ischemia/Reperfusion-Induced Acute Kidney Injury by Inhibiting Oxidative Stress, Inflammation, DNA Damage, and Apoptosis in Rats

Ischemia reperfusion (I/R) injury which causes kidney dysfunction is one of the most studied diseases directly linked to oxidative stress. In this regard, it is important to protect cells against damage by inducing antioxidant response. Herein, we aimed to evaluate the therapeutic roles and possible mechanisms of propolis and boric acid in kidney I/R injury based on relevant basic research and clinical studies. Sprague-Dawley rats were subjected to 50 min of ischemia followed by 3 h of reperfusion. Animals were randomly divided into a control group (the abdominal wall was just opened and closed), an I/R injury group, the propolis intervention group (200 mg/kg, intragastric administration, 1 h before ischemia), boric acid intervention group (14 mg/kg, intragastric administration 1 h before ischemia), and the propolis + boric acid intervention group (intragastric administration 1 h before ischemia). Kidney function, the antioxidant defensive system, and renal damage were assessed. In addition, the oxidative stress and inflammatory status were estimated in renal tissue. Furthermore, DNA damageand apoptosis were detected by immunohistochemistry. When compared with I/R group, propolis alone and especially propolis + boric acid groups significantly improved functional parameters. While the antioxidant response was increased, renal injury size and apoptosis were significantly decreased in both groups. Also, the MDA and TNF-α levels besides the 8-OHdG formation were downregulated. According to these outcomes, it can be said that especially propolis together with boric acid ameliorates kidney injury caused by I/R through acting as an antioxidant, anti-inflammatory, and antiapoptotic agent. In conclusion, propolis alone and its combination with boric acid could be developed as therapeutic agents against serious renal I/R injuries.

Oxiracetam ameliorates cognitive deficits in vascular dementia rats by regulating the expression of neuronal apoptosis/autophagy-related genes associated with the activation of the Akt/mTOR signaling pathway

Oxiracetam (ORC) is a commonly used nootropic drug for improving cognition and memory impairments. The therapeutic effect and underlying mechanism of ORC in vascular dementia (VaD) treatment remain unknown. In this study, 3-month-old male Sprague-Dawley rats with permanent bilateral common carotid artery occlusion-induced VaD were treated orally with low (100 mg/kg) or high (200 mg/kg) dose ORC once a day for 4 weeks. The results of the Morris water maze test and Nissl staining showed that ORC treatment significantly alleviated learning and memory deficits and neuronal damage in rats with VaD. Mechanistically, the protein levels of a panel of genes associated with neuronal apoptosis (Bcl-2, Bax) and autophagy (microtubule-associated protein 1 chain 3, Beclin1, p62) were significantly altered by ORC treatment compared with VaD, suggesting a protective role of ORC against VaD-induced neuronal apoptosis and autophagy. Moreover, the Akt/mTOR pathway, which is known to be the upstream signaling governing apoptosis and autophagy, was found to be activated in ORC-treated rats, suggesting an involvement of Akt/mTOR activation in ORC-rendered protection in VaD rats. Taken together, this study demonstrated that ORC may alleviate learning and memory impairments and neuronal damage in VaD rats by altering the expression of apoptosis/autophagy-related genes and activation of the Akt/mTOR signaling pathway in neurons.

Inhibition of high mobility group box 1 (HMGB1) attenuates podocyte apoptosis and epithelial-mesenchymal transition by regulating autophagy flux

BACKGROUND

Podocyte injury, characterized by podocyte hypertrophy, apoptosis, and epithelial-mesenchymal transition (EMT), is the major causative factor of diabetic nephropathy (DN). Autophagy dysfunction is regarded as the major risk factor for podocyte injury including EMT and apoptosis. High mobility group box 1 (HMGB1) is involved in the progression of DN through the induction of autophagy. However, the underlying mechanism remains unknown.

METHODS

Plasma HMGB1 concentrations were determined in DN patients using ELISA. Apoptosis of DN serum-treated podocytes was evaluated by flow cytometry. Podocyte autophagy flux was measured using immunofluorescence. Western blotting analysis was used to investigate HMGB1 expression, EMT, and autophagy-related signaling pathways.

RESULTS

Upregulation of HMGB1 was found in DN patients and DN serum-treated podocytes. Removal of HMGB1 inhibited DN serum-mediated podocyte apoptosis by inhibiting autophagy and activating AKT/mammalian target of rapamycin (mTOR) signaling. In addition, HMGB1 depletion repressed the progression of podocyte EMT by inhibiting transforming growth factor (TGF)-β/smad1 signaling in vitro and in vivo. The combination of HMGB1 short interference (si) RNA and the autophagy activator rapamycin protected against podocyte apoptosis and EMT progression by inhibiting the AKT/mTOR and TGF-β/smad signaling pathway, respectively.

CONCLUSIONS

Although HMGB1 siRNA and rapamycin treatment had opposite effects on autophagy and AKT/mTOR signaling, there was no contradiction about the role of HMGB1 siRNA and rapamycin on AKT/mTOR pathway because autophagy and AKT/mTOR signaling play dual roles in intracellular biological processes. Based on the findings of this study, we may assume that HMGB1-initiated autophagy is harmful, whereas rapamycin is beneficial to podocyte survival. Possibly combined treatment with HMGB1 siRNA and rapamycin improved podocyte damage and EMT by regulating autophagy homeostasis.