Glucagon-like peptide-1 protects cardiomyocytes from advanced oxidation protein product-induced apoptosis via the PI3K/Akt/Bad signaling pathway

Liraglutide ameliorates high glucose-induced vascular endothelial injury through TRIB3/NF-κB signaling pathway

As one of the most commonly used antidiabetic medications clinically, liraglutide is involved in the protection of vascular endothelium, and whether it can relieve high glucose-induced vascular endothelial damage was unknown. This study aims to address the response of liraglutide (LIRA) on human umbilical vein endothelial cells, as well as to elucidate its possible underlying mechanism. We established a vascular endothelial cell injury model by exposing human umbilical vein endothelial cells (HUVECs) to high glucose, and used LIRA pretreatment before HG treatment to address the endothelial protective effect of LIRA. Our results suggest that LIRA prevented HG-induced HUVEC apoptosis, oxidative stress, inflammasome activation, and pyroptosis. Furthermore, silencing of tribbles homolog 3 (TRIB3) could markedly reduce HG-induced HUVEC apoptosis, ROS level, the expressions of TXNIP, cleaved caspase3, NLRP3, and caspase1, indicating TRIB3 inhibition protected HUVECs against HG-induced vascular endothelial injury. In addition, LIRA restrained NF-κB/IκB-α signaling pathway activation in HUVECs. Thus, LIRA appears to mitigate HG-induced apoptosis, oxidative stress, inflammasome activation, and pyroptosis in HUVECs via regulating the TRIB3/NF-κB/IκB-α signaling pathway. Our study provides new insight into the mechanisms underlying the protective activity of LIRA against the vascular endothelial injury in diabetic vascular complication.

Semaglutide attenuates pathological electrophysiological remodeling in diabetic cardiomyopathy via restoring Cx43 expression

BACKGROUND

Semaglutide is a relatively new anti-hyperglycemic agent that was shown to carry cardioprotective potentials. However, the exact effects of semaglutide on diabetic cardiomyopathy (DCM) and their underlining mechanism remain unclear. This study aimed to evaluate the effects of semaglutide on myocardium injury and cardiac function in DCM mice and its potential mechanisms, with emphasis on its effects on Cx43 and electrophysiological remodeling.

METHODS

C57BL/6 mice were randomly divided into four groups: control group, semaglutide group, diabetes group, and diabetes + semaglutide treatment group. Type 1 diabetes were induced by intraperitoneal injection of streptozotocin. Mice in the semaglutide intervention group were injected subcutaneously with semaglutide (0.15 mg/kg) every week for 8 weeks. The blood glucose, cardiac function, oxidative stress markers, apoptosis, expression of Sirt1, AMPK, Cx43, and electrocardiogram of mice in each group were evaluated.

RESULTS

Treatment with semaglutide alleviated glucose metabolism disorders and improved cardiac dysfunction in diabetic mice. In addition, semaglutide ameliorated the increase in oxidative stress and apoptosis in diabetic heart. Sirt1/AMPK pathway was activated after semaglutide treatment. Furthermore, diabetic mice showed reduced expression of Cx43 in the myocardium, accompanied by changes in electrocardiogram, including significantly prolonged RR, QRS, QT and QTc interval. Semaglutide treatment restored Cx43 expression and reversed the above-mentioned ECG abnormalities.

CONCLUSIONS

Our research results showed that semaglutide protected against oxidative stress and apoptosis in diabetic heart, thereby improving cardiac function and electrophysiological remodelling in DCM mice, which may attribute to activation of Sirt1/AMPK pathway and restore of Cx43 expression.

LOW DOSE OF ESMOLOL ATTENUATES SEPSIS-INDUCED IMMUNOSUPPRESSION VIA MODULATING T-LYMPHOCYTE APOPTOSIS AND DIFFERENTIATION

ABSTRACT

Background: Immunosuppression caused by immune cell apoptosis and an imbalance of T helper 2 cells (T H 2) and T helper 1 cells (T H 1), is associated with poor outcomes in septic patients. Esmolol was reported to improve survival by modulating immune responses in septic shock. Whether esmolol could alleviate sepsis-induced immunosuppression and the optimal dose are unclear. Methods: Four hours after cecal ligation and puncture (CLP), Wistar rats were randomized into CLP, CLP + E-5 (esmolol: 5 mg·kg -1 ·h -1 ) and CLP + E-18 (esmolol: 18 mg·kg -1 ·h -1 ) groups. Eight rats were underwent sham operation. Eighteen hours after CLP, hemodynamics and organ histological injuries were evaluated, peripheral blood mononuclear cells apoptosis and T-lymphocyte subsets counts were determined by flow cytometry, and the expression of p-Akt, Bcl-2, cleaved Caspase-3, and p-Erk1/2 in splenic CD4 + T-lymphocytes was determined by western blot and immunohistochemistry. β 1 -Adrenoreceptor expressions were evaluated using real-time polymerase chain reaction and immunohistochemistry. Results: Cecal ligation and puncture induced tachycardia, hypotension, hyperlactatemia, and multiple organ injury. Heart rate was unchanged in the CLP + E-5 group but decreased in the CLP + E-18 group. Hypotension, lactatemia, and multiple organ injuries were improved only in the CLP + E-5 group. T-lymphocyte apoptosis and T H 2/T H 1 ratio was decreased in CLP + E-5 but not in CLP + E-18. p-Akt and Bcl-2 expressions were increased, while cleaved Caspase-3 and p-Erk1/2 expressions were decreased in CLP + E-5. β 1 -Adrenoreceptor expressions were unchanged in both CLP + E-5 and CLP + E-18 groups. Conclusions: Low dose of esmolol reduced T-lymphocyte apoptosis and restored T H 2/T H 1 ratio in septic shock. Esmolol might modulate Akt/Bcl-2/Caspase-3 pathway to relieve T-lymphocyte apoptosis and inhibit Erk1/2 activity to decrease T H 0 differentiation to T H 2. Esmolol may be a potential immunoregulator of septic shock.

Glukagon benzeri peptit-1'in yağ doku kaynaklı mezenkimal kök hücrelerinin kardiyomiyositlere dönüşmesi üzerindeki etkisi

Amaç: Mezenkimal kök hücreler, çeşitli protokoller kullanılarak in vitro koşullarda kolaylıkla kardiyomiyositlere farklılaşabilir. Ancak bu protokollerde kullanılan ajanların hücre canlılığı üzerinde bazı olumsuz etkileri olduğu bildirilmiştir. Azasitidin mezenkimal kök hücreleri kalp kası hücrelerine farklandırmak için kullanılmaktadır. Bu çalışmanın amacı, bir GLP-1 reseptör agonisti olan Eksenatid'in insan yağ dokusu kaynaklı kök hücrelerinin kardiyomiyositlere farklılaşması ve canlılığı üzerindeki etkilerini araştırmaktır. Gereç ve Yöntem: Azasitidin ve Eksenatid'in insan yağ doku kaynaklı mezenkimal kök hücreler üzerinde hücre canlılığı ve proliferasyonu üzerindeki etkileri ile sitotoksisite testleri yapıldı. Farklılanma protokolü için, hücreler dört hafta boyunca Azasitidin ve Eksenatid ile inkübe edildi. Hücrelerin morfolojik değişiklikleri izlendi ve kardiyomiyojenik farklılaşma belirteçlerinin (cTnI, GATA4 ve MYH7) ekspresyonları immünohistokimyasal olarak değerlendirildi. Ayrıca kültürlerdeki kardiyak troponin I (cTnI) seviyeleri enzime bağlı immünosorbent testi kullanılarak ölçüldü. Veriler, tek yönlü varyans analizi (ANOVA) ve post-hoc testi ile değerlendirildi. Bulgular: İnsan yağ doku kaynaklı mezenkimal kök hücreler üzerine Azasitidin uygulaması, kontrole grubuna kıyasla hücre canlılığını önemli ölçüde azaltırken (%54.4) hücrelerin Azasitidin+Eksenatid ile uygulaması doza bağlı bir şekilde hücre ölümünü önledi. Azasitidin ve Eksenatid uygulanan hücreler, kardiyomiyojenik farklılaşma ile uyumlu önemli morfolojik değişiklikler ve kardiyomiyojenik belirteçlerde artış gösterdi. Ayrı ayrı ve birlikte uygulama yapılan gruplarda cTnI seviyeleri kontrole göre anlamlı derecede yüksek bulundu. Sonuç: Bu bulgular GLP-1 reseptör agonisti Eksenatid'in, Azasitidin uygulamasının neden olduğu hücre hasarını azaltarak İnsan yağ doku kaynaklı mezenkimal kök hücrelerin kardiyomiyojenik farklılaşması üzerinde faydalı etkileri olabileceğini düşündürmektedir.

The potential of glucagon-like peptide-1 receptor agonists in heart failure

Heart failure (HF) remains one of the cardiovascular diseases (CVDs) associated with a high unmet medical need due to high morbidity and mortality rates and lack of efficacious interventions. HF is closely related to cardiometabolic diseases such as diabetes, obesity and chronic kidney disease, and strategies that address most or all these intertwined conditions are desirable. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are approved for type 2 diabetes (T2D), and some are also indicated for reduction of the risk of atherosclerotic CVD in T2D and for weight management. As we summarise in this concise review, preliminary evidence suggests that the cardioprotective benefits of GLP-1 RAs may also extend to HF. The most robust clinical evidence arguably originates from the large cardiovascular outcomes trials (CVOTs) completed for most GLP-1 RAs, of which the latest showed a significant relative risk reduction (RRR) of 39% (HR) with once-weekly efpeglenatide on HF requiring hospitalisation, corroborating a meta-analysis which found a significant RRR across eight GLP-1 RA CVOTs of 11%. Further, although incompletely described, multiple studies are available to provide insights into the mechanistic underpinnings, which appear to be associated mostly with indirect cardioprotective benefits owing to the ability of GLP-1 RAs to address hyperglycaemia, and reduce body weight, and, amongst others, inflammation. In sum, current evidence positions GLP-1 RAs as a potential cardioprotective strategy in HF, with HF with preserved ejection fraction emerging as the clinically most relevant phenotype for the drug class, especially when occurring in people with obesity with and without diabetes.

Multiple Mechanistic Action of Brevinin-1FL Peptide against Oxidative Stress Effects in an Acute Inflammatory Model of Carrageenan-Induced Damage

Amphibian skin is acknowledged to contain an antioxidant system composed of various gene-encoded antioxidant peptides, which exert significant effects on host defense. Nevertheless, recognition of such peptides is in its infancy so far. Here, we reported the antioxidant properties and underlying mechanism of a new antioxidant peptide, brevinin-1FL, identified from Fejervarya limnocharis frog skin. The cDNA sequence encoding brevinin-1FL was successfully cloned from the total cDNA of F. limnocharis and showed to contain 222 bp. The deduced mature peptide sequence of brevinin-1FL was FWERCSRWLLN. Functional analysis revealed that brevinin-1FL could concentration-dependently scavenge ABTS⁺, DPPH, NO, and hydroxyl radicals and alleviate iron oxidation. Besides, brevinin-1FL was found to show neuroprotective activity by reducing contents of MDA and ROS plus mitochondrial membrane potential, increasing endogenous antioxidant enzyme activity, and suppressing H₂O₂-induced death, apoptosis, and cycle arrest in PC12 cells which were associated with its regulation of AKT/MAPK/NF-κB signal pathways. Moreover, brevinin-1FL relieved paw edema, decreased the levels of TNF-α, IL-1β, IL-6, MPO, and malondialdehyde (MDA), and restored catalase (CAT) and superoxide dismutase (SOD) activity plus glutathione (GSH) contents in the mouse injected by carrageenan. Together, these findings indicate that brevinin-1FL as an antioxidant has potent therapeutic potential for the diseases induced by oxidative damage. Meanwhile, this study will help us further comprehend the biological functions of amphibian skin and the mechanism by which antioxidants protect cells from oxidative stress.

Baicalein Preconditioning Cardioprotection Involves Pro-Oxidant Signaling and Activation of Pyruvate Dehydrogenase

Preconditioning has a powerful protective potential against myocardial ischemia-reperfusion injury (I/R). Our prior work demonstrated that baicalein, a flavonoid derived from the root of Scatellaria baicalensis Georgi (also known as Huangqin), confers this preconditioning protection. This study further explored the mechanisms of baicalein preconditioning (BC-PC) in mouse cardiomyocytes. Cells were treated with baicalein (10 μM) for a brief period of time (10 min) prior to simulated ischemia 90 min/reperfusion for 180 min. Baicalein triggered an induction of a small amount of mitochondrial reactive oxygen species (ROS) prior to the initiation of ischemia, assessed by 6-carboxy-2^', 7^'-dichlorodihydrofluorescein diacetate (6-carboxy-H₂DCFDA). It also significantly increased cell viability measured by propidium iodide (PI) and lactate dehydrogenase and preserved mitochondrial membrane potential assessed by TMRM fluorescence intensity. Myxothiazol, a mitochondrial electron transport chain complex III inhibitor, partially blocked ROS generation induced by BC-PC and reduced cell viability. BC-PC increased phosphorylation of Akt (Thr308 and Ser473) and eNOS Ser1177, and nitric oxide (NO) production measured using 4,5-diaminofluorescein diacetate (DAF-2 DA, 1 μM). Akt inhibitor API-2 abolished Akt phosphorylation and reduced DAF-2 production and cell viability. In addition, BC-PC decreased phosphorylation of pyruvate dehydrogenase (PDH) reflecting upregulated PDH activity, and increased ATP production at 30 min during reperfusion. Taken together, baicalein preconditioning-induced cardioprotection involves pro-oxidant generation, activates survival signaling Akt/eNOS/NO, and improves metabolic recovery after I/R injury. Our work provides new perspectives on the effect of baicalein on cardiac preconditioning against I/R injury.

Potential new therapeutic target for Alzheimer's disease: Glucagon-like peptide-1

Increasing evidence shows a close relationship between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM). Recently, glucagon-like peptide-1 (GLP-1), a gut incretin hormone, has become a well-established treatment for T2DM and is likely to be involved in treating cognitive impairment. In this mini review, the similarities between AD and T2DM are summarised with the main focus on GLP-1-based therapeutics in AD.

Quercetin improves myocardial redox status in rats with type 2 diabetes

Objective. Emerging data indicate that oxidative stress is closely associated with the pathogenesis of cardiovascular disease in type 2 diabetes mellitus (T2DM). The present study aimed to assess the effect of the most abundant flavonoid in the human diet quercetin (Q) on the myocardial redox status in rats with T2DM. Methods. T2DM was induced in male Wistar rats by a high caloric diet (for 14 weeks) and two streptozotocin (25 mg/kg b.w.) injections applied in four weeks of the diet, once a week for two weeks. The Q was administered intragastrically by gavage in a dose of 10 or 50 mg/kg of the body weight for 8 weeks starting from the 8th day after the last streptozotocin injection. The control rats received citrate buffer and seven days after the last STZ injection, basal glucose levels were measured in all animals. Results. Administration of Q increased insulin sensitivity in diabetic rats with more pronounced effect at a dose of 50 mg/kg b.w. The Q also decreased free radical oxidation in the heart mitochondria of diabetic animals, thus limiting the formation of advanced oxidation protein products in a dose-dependent manner and normalized the activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase) in cardiac mitochondria independently of the dose used. In addition, the Q in both doses prevented the development of oxidative stress in the T2DM rats cardiomyocytes by reducing NADPH oxidase and xanthine oxidase activities. Conclusions. The findings demonstrate that Q in both doses 10 mg/kg and 50 mg/kg can protect from the development of oxidative stress in cardiomyocytes in the diabetic rats. The present data indicate that the use of Q may contribute to the amelioration of cardiovascular risk in patients with T2DM.

The cardioprotective effect and mechanism of bioactive glass on myocardial reperfusion injury

Myocardial reperfusion treatment for ischemic infarction may cause lethal injury of cardiomyocytes, which is known as ischemia/reperfusion (I/R) injury. As a kind of prospective biomaterial with superior properties, the application of bioactive glasses (BGs) in myocardial tissue engineering have received great interests. In this study, the cardioprotective effect and relevant mechanism of BG on myocardial reperfusion injury were investigatedin vitro. H9c2 cardiomyocytes were pretreated with BG extracts and then cultured in hypoxic environment for 30 min followed by reoxygenation for 1 h. The activity of released lactate dehydrogenase (LDH) and the content of malondialdehyde (MDA) in H9c2 cells were tested by assay kits. Cell viability was analyzed by Live/Dead staining assay and the number of living cells was detected by Cell Counting Kit-8 (CCK-8) assay. The cytoskeletal protein F-actin was stained and observed under inverted fluorescence microscope. Mitochondrial membrane potential (MMP) level, reactive oxygen species (ROS) production and apoptosis ratio were evaluated by fluorescent observation and flow cytometry simultaneously. The gene expressions relevant to apoptosis were detected by quantitative real time polymerase chain reaction (qRT-PCR) analysis. The results showed that BG extracts effectively inhibited hypoxia/reoxygenation (H/R)-induced cell injury by suppressing oxidative stress and mitochondrial permeability transition (MPT) within H9c2 cells. Meanwhile, apoptosis caused by H/R injury was alleviated and three classic apoptotic signaling pathways were proved to be regulated by BG extracts. Further analysis showed that phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was up-regulated in H/R-induced H9c2 cells by BG extracts, leading to relieved cellular apoptosis. These results indicated that BG might exert cardioprotective effect in reperfusion injury when applied in myocardial tissue regeneration and repair.

Bioactive glass activates VEGF paracrine signaling of cardiomyocytes to promote cardiac angiogenesis

The heart contains a wide range of cell types, which are not isolated but interact with one another via multifarious paracrine, autocrine and endocrine factors. In terms of cardiac angiogenesis, previous studies have proved that regulating the communication between cardiomyocytes and endothelial cells is efficacious to promote capillary formation. Firstly, this study investigated the effect and underlying mechanism of bioactive glass (BG) acted on vascular endothelial growth factor (VEGF) paracrine signaling in cardiomyocytes. We found that bioactive ions released from BG significantly promoted the VEGF production and secretion of cardiomyocytes. Subsequently, we proved that cardiomyocyte-derived VEGF played an important role in mediating the behavior of endothelial cells. Further research showed that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway was upregulated by BG, which was involved in VEGF expression of cardiomyocytes. This study revealed that by means of modulating cellular crosstalk via paracrine signaling of host cells in heart is a new direction for the application of BGs in cardiac angiogenesis.

Aloe-emodin relieves zidovudine-induced injury in neonatal rat ventricular myocytes by regulating the p90rsk/p-bad/bcl-2 signaling pathway

BACKGROUND/AIMS

Zidovudine (3'-azido-2',3'-deoxythymidine; AZT) is a first-line drug for treatment of human immunodeficiency virus infection (HIV). However, its application is limited by cardiotoxicity due to cardiomyocyte injury. This study investigated whether Aloe-emodin (AE), an anthraquinone compound, protects against AZT-induced cardiomyocyte toxicity.

METHODS

MTT, JC-1 assays and TUNEL were examined to verify the protective effect of AE against AZT-induced cardiomyocyte injury. Western blotting was performed to explore the anti-apoptotic effect of AE using anti-apoptotic proteins p90rsk, p-bad, and bcl-2 and pro-apoptotic proteins apaf-1, cleaved-caspase-3, and cytochrome c.

RESULTS

We observed a protective effect of AE against cell viability decrease and TUNEL positive cells increase induced by AZT, which was counteracted by BI-D1870. Western blot analysis found that AE significantly inhibited cardiomyocyte apoptosis by activating p90rsk/p-bad/bcl-2 signaling pathway. Furthermore, BI-D1870 counteracted the anti-apoptotic effect of AE.

CONCLUSIONS

Taken together, these results indicate that AE attenuated AZT-induced cardiomyocyte apoptosis by activating p90rsk.

Liraglutide Improves Endothelial Function via the mTOR Signaling Pathway

BACKGROUND

Mammalian target of rapamycin (mTOR) is crucial for endothelial function. This study is aimed at assessing whether the glucagon-like peptide-1 (GLP-1) analogue liraglutide has a protective effect on endothelial function via the mTOR signaling pathway.

METHODS

Human umbilical vein endothelial cells (HUVECs) were administered liraglutide (100 nM) for 0, 10, 30, 60, 720, and 1440 minutes, respectively. Then, the expression and phosphorylation levels of mTOR, mTOR-Raptor complex (mTORC1), and mTOR-Rictor complex (mTORC2) were determined by Western blot and immunoprecipitation, while mTORC1 and mTORC2 expression was blocked by siRNA-Raptor and siRNA-Rictor, respectively. Akt phosphorylation was detected by Western blot. HUVECs were then incubated with liraglutide in the absence or presence of Akt inhibitor IV. Nitric oxide (NO) release was assessed by the nitrate reductase method. Phosphorylated endothelial nitric oxide synthase (eNOS), human telomerase reverse transcriptase (hTERT), and apoptosis-related effectors were assessed for protein levels by Western blot. Telomerase activity was evaluated by ELISA.

RESULTS

Sustained mTOR phosphorylation, mTORC2 formation, and mTORC2-dependent Akt phosphorylation were induced by liraglutide. In addition, eNOS phosphorylation, NO production, nuclear hTERT accumulation, and nuclear telomerase activity were enhanced by mTORC2-mediated Akt activation. Liraglutide also showed an antiapoptotic effect by upregulating antiapoptotic proteins and downregulating proapoptotic proteins in an mTORC2-Akt activation-dependent manner.

CONCLUSION

Liraglutide significantly improves endothelial function, at least partially via the mTORC2/Akt signaling pathway.

Taurine with combined aerobic and resistance exercise training alleviates myocardium apoptosis in STZ-induced diabetes rats via Akt signaling pathway

AIM

The aim of this study was considering the effects of taurine supplementation with combined aerobic and resistance training (CARE) on myocardial apoptosis and Protein Kinase B (akt) level changes in diabetic rat.

MAIN METHODS

Forty male Wistar rats were randomly divided in to 5 groups of 8 animals in each: 1) control, 2) Diabetes Mellitus (DM), 3) DM with taurine supplementation (DM/T), 4) DM with CARE (DM/CARE), and 5) DM with combination of taurine and CARE (DM/T/CARE). DM was induced by injection of streptozotocin (STZ) and nicotine amid (NA) for 2, 3, 4 and 5 groups. Supplement groups received taurine in gavage, 100 mg/kg of body weight, 6 day per weeks, 8 weeks. CARE was performed at maximal speed and 1RM (40-60% of maximum for both).

KEY FINDINGS

The results of this study showed that DM significantly increased blood glucose and caspase 3, caspase 9 expressions and apoptosis cells in heart tissue and reduced Akt expression (p < 0.001). However, taurine and CARE interventions significantly decreased apoptosis markers (caspase 3 and caspase 9) and significantly increased Akt in heart of diabetic rats compare to DM groups (p < 0.05). The highest improvement observed in DM/T/CARE group (p < 0.05).

SIGNIFICANCE

Based on these results, it seems that the use of taurine with combined aerobic and exercise training minimize the cardiac damage caused by diabetes (especially apoptosis) trough increasing protein kinase Akt expression. This could improve cardiac remodeling after diabetes. However, more research is needed, especially on the human samples.

The protective effect of soybean protein-derived peptides on apoptosis via the activation of PI3K-AKT and inhibition on apoptosis pathway

Soybean protein-derived peptides (SBP) are a rich source of various bioactive peptides with multiple health benefits. However, the prospective effects of SBP on human cells are still unclear. Therefore, this article investigated the effects of small molecular weight SBP on MG132-induced apoptosis in RAW264.7 cells. SBP inhibited MG132-induced apoptosis of RAW264.7 cells in a dose-dependent manner by flow cytometry. To further study its molecular mechanisms, Western blot analysis demonstrated that SBP could activate the PI3K-AKT pathway by increasing the phosphorylation of PI3K and AKT and inhibiting apoptosis pathway by downregulating the expressions of pro-apoptotic proteins of Bim, Bax, Fas, and Fasl and promoting the expressions of anti-apoptotic proteins of Bcl-xL and Bcl-2. These results indicated the protective effect of SBP on MG132-induced apoptosis in RAW264.7 cells.

Astaxanthin alleviates spinal cord ischemia-reperfusion injury via activation of PI3K/Akt/GSK-3β pathway in rats

BACKGROUND

Ischemia-reperfusion injury of the spinal cord (SCII) often leads to unalterable neurological deficits, which may be associated with apoptosis induced by oxidative stress and inflammation. Astaxanthin (AST) is a strong antioxidant and anti-inflammatory agent with multitarget neuroprotective effects. This study aimed to investigate the potential therapeutic effects of AST for SCII and the molecular mechanism.

METHODS

Rat models of SCII with abdominal aortic occlusion for 40 min were carried out to investigate the effects of AST on the recovery of SCII. Tarlov's scores were used to assess the neuronal function; HE and TUNEL staining were used to observe the pathological morphology of lesions. Neuron oxidative stress and inflammation were measured using commercial detection kits. Flow cytometry was conducted to assess the mitochondrial swelling degree. Besides, Western blot assay was used to detect the expression of PI3K/Akt/GSK-3β pathway-related proteins, as well as NOX2 and NLRP3 proteins.

RESULTS

The results demonstrated that AST pretreatment promoted the hind limb motor function recovery and alleviated the pathological damage induced by SCII. Moreover, AST significantly enhanced the antioxidative stress response and attenuated mitochondrial swelling. However, AST pretreatment hardly inhibited the levels of proinflammatory cytokines after SCII. Most importantly, AST activated p-Akt and p-GSK-3β expression levels. Meanwhile, cotreatment with LY294002 (a PI3K inhibitor) was found to abolish the above protective effects observed with the AST pretreatment.

CONCLUSION

Overall, these results suggest that AST pretreatment not only mitigates pathological tissue damage but also effectively improves neural functional recovery following SCII, primarily by alleviating oxidative stress but not inhibiting inflammation. A possible underlying molecular mechanism of AST may be mainly attributed to the activation of PI3K/Akt/GSK-3β pathway.

Inhibition of PHLPP1 ameliorates cardiac dysfunction via activation of the PI3K/Akt/mTOR signalling pathway in diabetic cardiomyopathy

Background

Pleckstrin homology (PH) domain leucine‐rich repeat protein phosphatase 1 (PHLPP1) is a kind of serine/threonine phosphatase, whose dysregulation is accompanied with numerous human diseases. However, its role in diabetic cardiomyopathy remains unclear. We explored the underlying function and mechanism of PHLPP1 in diabetic cardiomyopathy (DCM).

Method

In vivo, Type 1 diabetic rats were induced by intraperitoneal injection of 60 mg/kg streptozotocin (STZ). Lentivirus‐mediated short hairpin RNA (shRNA) was used to knock down the expression of PHLPP1. In vitro, primary neonatal rat cardiomyocytes and H9C2 cells were incubated in 5.5 mmol/L glucose (normal glucose, NG) or 33.3 mmol/L glucose (high glucose, HG). PHLPP1 expression was inhibited by PHLPP1‐siRNA to probe into the function of PHLPP1 in high glucose‐induced apoptosis in H9c2 cells.

Results

Diabetic rats showed up‐regulated PHLPP1 expression, left ventricular dysfunction, increased myocardial apoptosis and fibrosis. PHLPP1 inhibition alleviated cardiac dysfunction. Additionally, PHLPP1 inhibition significantly reduced HG‐induced apoptosis and restored PI3K/AKT/mTOR pathway activity in H9c2 cells. Furthermore, pretreatment with LY294002, an inhibitor of PI3K/Akt/mTOR pathway, abolished the anti‐apoptotic effect of PHLPP1 inhibition.

Conclusion

Our study indicated that PHLPP1 inhibition alleviated cardiac dysfunction via activating the PI3K/Akt/mTOR signalling pathway in DCM. Therefore, PHLPP1 may be a novel therapeutic target for human DCM.

Icariin induces apoptosis of human lung adenocarcinoma cells by activating the mitochondrial apoptotic pathway

Lung cancer is the largest cause of morbidity and mortality among tumor diseases. Traditional first-line chemotherapeutic drugs are frequently accompanied by serious side effects when used to treat tumors, thus, novel drugs with reduced toxic effects may improve a patients' quality of life. Icariin, an extract of herba epimedii, has been demonstrated to exhibit multiple antitumor effects with low toxicity. In the present study, cell cycle analysis, apoptosis assays, DAPI staining, CCK8 assays, xenograft tumor models, mitochondrial membrane potential analysis, western blotting and reverse transcription-quantitative PCR were performed to determine the molecular mechanism underlying icariin activity in the human lung adenocarcinoma cell lines, A549 and H1975. The results showed that icariin reduced proliferation of A549 and H1975 cells in a time- and dose-dependent manner in vitro to a greater degree than the control BEAS-2B cells, and this was associated with increased apoptosis, but not with cell cycle progression. In vivo experiments showed that icariin treatment significantly decreased proliferation of H1975 cells in a xenograft mouse model. Mechanistically, icariin activated the mitochondrial pathway by inhibiting the activation of the PI3K-Akt pathway-associated kinase, Akt, resulting in the activation of members of the caspase family of proteins, and thus inducing apoptosis of A549 cells. Taken together, the results revealed that icariin has anti-cancer properties in lung cancer in vitro and in vivo without any noticeable toxic effects on normal lung epithelial cells. Icariin in combination with conventional anti-cancer agents may be an effective therapeutic strategy for treatment of lung carcinoma.

Tilianin-loaded Reactive Oxygen Species-Scavenging Nano-Micelles Protect H9c2 Cardiomyocyte Against Hypoxia/Reoxygenation-Induced Injury

Previous studies have shown that tilianin alleviates ischemia-reperfusion-induced cardiomyocyte injury. However, its clinical translation has been hampered because of its insolubility in water. Tilianin-based nano-micelles that may overcome this critical issue are presented. A polyethylene glycol compound was covalently attached to propylene sulfide-formed amphiphilic diblock polymers. In the aqueous solution, tilianin is encapsulated in a hydrophobic shell to form nano-micelles. The Ph-PPS-PEG self-assembled into nanoscale micelles with a size of approximately 70 nm, termed "tilianin-loaded micelles" (TLMs). TLMs are highly efficient hydrogen peroxide scavengers and the activity of caspase-3 inhibition, thereby protecting cells from H/R-induced cytotoxicity. In addition, TLMs decreased levels of MDA, IL-1 and tumor necrosis factor (TNF-α), inhibited apoptosis, TLR4 and nuclear transcription factor (NF-κB p65) protein expression in hypoxia-reoxygenation (H/R) model. Taken together, the study suggests that TLMs may be of clinical value for the protective effects of cardiomyocytes by inhibiting Inflammation and oxidative stress during myocardial ischemia-reperfusion injury.

Panax notoginseng saponins promote liver regeneration through activation of the PI3K/AKT/mTOR cell proliferation pathway and upregulation of the AKT/Bad cell survival pathway in mice

Backgroud

The regenerative capacity of the liver is crucial for the host to survive after serious hepatic injuries, tumor resection, or living donor liver transplantation. Panax notoginseng saponins (PNS) have been reported to exert protective effects during organ injuries. The present study aimed to evaluate the effect of PNS on liver regeneration(LR) and on injuries induced by partial hepatectomy (PH).

Methods

We performed 70% partial PH on C57BL/6 J mice treated with or without PNS. LR was estimated by liver weight/body weight, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and cell proliferation, and the related cellular signals were analyzed by Western blot.

Results

Different concentrations of PNS promoted hepatocyte proliferation in vitro. Mice in the PNS group showed higher liver/body weight ratios at 2 d and 7 d (P < 0.05) after PH and lower levels of serum ALT and AST (P < 0.05) compared to those of mice in the normal control (NC) group. Histological analysis showed that the expression of proliferating cell nuclear antigen(PCNA) at 2 d and 7 d after PH was significantly higher in the PNS group than in the NC group (P < 0.05). Mechanistically, the AKT/mTOR cell proliferation pathway and AKT/Bad cell survival pathway were activated by PNS, which accelerated hepatocyte proliferation and inhibited apoptosis (P < 0.05).

Conclusions

PNS promoted liver regeneration through activation of PI3K/AKT/mTOR and upregulated the AKT/Bad cell pathways in mice.

Cardioprotection Conferred by Sitagliptin Is Associated with Reduced Cardiac Angiotensin II/Angiotensin-(1-7) Balance in Experimental Chronic Kidney Disease

Dipeptidyl peptidase IV (DPPIV) inhibitors are antidiabetic agents that exert renoprotective actions independently of glucose lowering. Cardiac dysfunction is one of the main outcomes of chronic kidney disease (CKD); however, the effects of DPPIV inhibition on cardiac impairment during CKD progression remain elusive. This study investigated whether DPPIV inhibition mitigates cardiac dysfunction and remodeling in rats with a 5/6 renal ablation and evaluated if these effects are associated with changes in the cardiac renin-angiotensin system (RAS). To this end, male Wistar rats underwent a 5/6 nephrectomy (Nx) or sham operation, followed by an 8-week treatment period with the DPPIV inhibitor sitagliptin (IDPPIV) or vehicle. Nx rats had lower glomerular filtration rate, overt albuminuria and higher blood pressure compared to sham rats, whereas CKD progression was attenuated in Nx + IDPPIV rats. Additionally, Nx rats exhibited cardiac hypertrophy and fibrosis, which were associated with higher cardiac DPPIV activity and expression. The sitagliptin treatment prevented cardiac fibrosis and mitigated cardiac hypertrophy. The isovolumic relaxation time (IRVT) was higher in Nx than in sham rats, which was suggestive of CKD-associated-diastolic dysfunction. Sitagliptin significantly attenuated the increase in IRVT. Levels of angiotensin II (Ang II) in the heart tissue from Nx rats were higher while those of angiotensin-(1-7) Ang-(1-7) were lower than that in sham rats. This cardiac hormonal imbalance was completely prevented by sitagliptin. Collectively, these results suggest that DPPIV inhibition may delay the onset of cardiovascular impairment in CKD. Furthermore, these findings strengthen the hypothesis that a crosstalk between DPPIV and the renin-angiotensin system plays a role in the pathophysiology of cardiorenal syndromes.

Expression of Pro- and Antiapoptotic Factors in Multinuclear Macrophages of BCG-Infected Mice In Vitro

Intraperitoneal infection of Mycobacterium tuberculosis from BCG vaccine to male BALB/c mice provoked the formation of multinuclear macrophages in the peritoneal transudate. In 2 and 3 months after infection, their number increased respectively by 34.4 and 66.7% in comparison with intact mice. At all postinfection terms, far greater amounts of caspase 3, p53, Bad, and TNFα were expressed by multinuclear macrophages than by the mononuclear ones. At these terms, the content of Bcl-2-expressing macrophages with different numbers of nuclei was pronouncedly high; of them, the number of multinuclear macrophages was maximum. In 3 months after infection, the number of macrophages expressing Bcl-2 significantly decreased irrespective of the number of their nuclei. At this term, the number of macrophages expressing caspase 3, and TNFα also decreased. In parallel, the number of macrophages expressing p53 and Bad somewhat increased. These data attest to potentiality ("readiness") of macrophages infected with Mycobacterium tuberculosis to apoptotic self-elimination.

Sitagliptin attenuates myocardial apoptosis via activating LKB-1/AMPK/Akt pathway and suppressing the activity of GSK-3β and p38α/MAPK in a rat model of diabetic cardiomyopathy

The present study aimed to investigate the protective effect of sitagliptin, a dipeptidyl peptidase-4 inhibitor, on diabetic cardiomyopathy (DCM)-associated apoptosis and if this effect is mediated via modulating the activity of the survival kinases; AMP-activated protein kinase (AMPK) and Akt & the apoptotic kinases; glycogen synthase kinase-3 β (GSK-3β) and p38 mitogen-activated protein kinase (p38MAPK). Diabetes was induced by a single intraperitoneal injection of streptozotocin (55 mg/kg). Diabetic rats were treated with sitagliptin (10 mg/kg/day, p.o.) and metformin (200 mg/kg/day, p.o. as positive control) for six weeks. Chronic hyperglycemia resulted in elevation of serum cardiac biomarkers reflecting cardiac damage which was supported by H&E stain. The mRNA levels of collagen types I and III were augmented reflecting cardiac fibrosis and hypertrophy which was supported by Masson trichome stain and enhanced phosphorylation of p38MAPK. Cardiac protein levels of cleaved casapse-3, BAX were elevated, whereas, the levels of Bcl-2 and p-BAD were reduced indicating cardiac apoptosis which could be attributed to the diabetes-induced reduced phosphorylation of Akt and AMPK with concomitant augmented activation of GSK-3β and p38MAPK. Protein levels of liver kinase B-1, the upstream kinase of AMPK were also supressed. Sitagliptin administration alleviated the decreased phosphorylation of AMPK and Akt, inactivated the GSK-3β and p38 AMPK, therefore, attenuating the apoptosis and hypertrophy induced by hyperglycemia in the diabetic heart. In conclusion, sitagliptin exhibits valuable therapeutic potential in the management of DCM by attenuating apoptosis. The underlying mechanism may involve the modulating activity of AMPK, Akt, GSK-3β and p38MAPK.

The cardioprotective effect of dihydromyricetin prevents ischemia-reperfusion-induced apoptosis in vivo and in vitro via the PI3K/Akt and HIF-1α signaling pathways

Reperfusion therapy is widely used to treat acute myocardial infarction (AMI). However, further injury to the heart induced by rapidly initiating reperfusion is often encountered in clinical practice. A lack of pharmacological strategies in clinics limits the prognosis of patients with myocardial ischemia-reperfusion injury (MIRI). Dihydromyricetin (DMY) is one of the most abundant components in vine tea, commonly known as the tender stems and leaves of Ampelopsis grossedentata. The aim of this study was to evaluate the cardioprotection of DMY against myocardial ischemia-reperfusion (I/R) injury and to further investigate the underlying mechanism. An I/R injury was induced by left anterior descending coronary artery occlusion in adult male rats in vivo and a hypoxia-reoxygenation (H/R) injury in H9c2 cardiomyocytes in vitro. We found that DMY pretreatment provided significant protection against I/R-induced injury, including enhanced antioxidant capacity and inhibited apoptosis in vivo and in vitro. This effect correlated with the activation of the PI3K/Akt and HIF-1α signaling pathways. Conversely, blocking Akt activation with the PI3K inhibitor LY294002 effectively suppressed the protective effects of DMY against I/R-induced injury. In addition, the PI3K inhibitor partially blocked the effects of DMY on the upregulation of Bcl-2, Bcl-xl, procaspase-3, -8, and -9 protein expression and the downregulation of HIF-1α, Bnip3, Bax, Cyt-c, cleaved caspase-3, -8, and -9 protein expression. Collectively, these results showed that DMY decreased the apoptosis and necrosis by I/R treatment, and PI3K/Akt and HIF-1α plays a crucial role in protection during this process. These observations indicate that DMY has the potential to exert cardioprotective effects against I/R injury and the results might be important for the clinical efficacy of AMI treatment.

Integrative network analysis highlights biological processes underlying GLP-1 stimulated insulin secretion: A DIRECT study

Glucagon-like peptide 1 (GLP-1) stimulated insulin secretion has a considerable heritable component as estimated from twin studies, yet few genetic variants influencing this phenotype have been identified. We performed the first genome-wide association study (GWAS) of GLP-1 stimulated insulin secretion in non-diabetic individuals from the Netherlands Twin register (n = 126). This GWAS was enhanced using a tissue-specific protein-protein interaction network approach. We identified a beta-cell protein-protein interaction module that was significantly enriched for low gene scores based on the GWAS P-values and found support at the network level in an independent cohort from Tübingen, Germany (n = 100). Additionally, a polygenic risk score based on SNPs prioritized from the network was associated (P < 0.05) with glucose-stimulated insulin secretion phenotypes in up to 5,318 individuals in MAGIC cohorts. The network contains both known and novel genes in the context of insulin secretion and is enriched for members of the focal adhesion, extracellular-matrix receptor interaction, actin cytoskeleton regulation, Rap1 and PI3K-Akt signaling pathways. Adipose tissue is, like the beta-cell, one of the target tissues of GLP-1 and we thus hypothesized that similar networks might be functional in both tissues. In order to verify peripheral effects of GLP-1 stimulation, we compared the transcriptome profiling of ob/ob mice treated with liraglutide, a clinically used GLP-1 receptor agonist, versus baseline controls. Some of the upstream regulators of differentially expressed genes in the white adipose tissue of ob/ob mice were also detected in the human beta-cell network of genes associated with GLP-1 stimulated insulin secretion. The findings provide biological insight into the mechanisms through which the effects of GLP-1 may be modulated and highlight a potential role of the beta-cell expressed genes RYR2, GDI2, KIAA0232, COL4A1 and COL4A2 in GLP-1 stimulated insulin secretion.

Effects of icariside II ameliorates diabetic cardiomyopathy in streptozotocin-induced diabetic rats by activating Akt/NOS/NF-κB signaling

Icariside II is a flavonoid extracted from Epimedium that has antioxidant, anti‑inflammatory and antiapoptotic effects. The aim of the present study was to evaluate the effects icariside II on diabetic cardiomyopathy in streptozotocin-induced diabetic rats. Icariside II treatment improved body weight, heart/body weight ratio and fasting blood glucose in diabetic model rats. Icariside II was demonstrated to reduce the expression levels of creatine kinase and lactate dehydrogenase in serum, and to lower cardiac oxidative stress, inflammation and apoptosis levels in diabetic rats. Icariside II treatment induced phosphoinositide 3‑kinase and phosphorylated‑Akt expression, and suppressed inducible nitric oxide synthase (iNOS) and nuclear factor (NF)‑κB protein expression in diabetic rat. Results from the present study suggested that treatment with icariside II improved diabetic cardiomyopathy in streptozotocin‑induced diabetic rats by activating the Akt/NOS/NF‑κB pathway.

miR-19a protects cardiomyocytes from hypoxia/reoxygenation-induced apoptosis via PTEN/PI3K/p-Akt pathway

miRNAs have been implicated in processing of cardiac hypoxia/reoxygenation (H/R)-induced injury. Recent studies demonstrated that miR-19a might provide a potential cardioprotective effect on myocardial disease. However, the effect of miR-19a in regulating myocardial ischemic injury has not been previously addressed. The present study was to investigate the effect of miR-19a on myocardial ischemic injury and identified the potential molecular mechanisms involved. Using the H/R model of rat cardiomyocytes H9C2 in vitro, we found that miR-19a was in low expression in H9C2 cells after H/R treatment and H/R dramatically decreased cardiomyocyte viability, and increased lactate dehydrogenase (LDH) release and cardiomyocyte apoptosis, which were attenuated by co-transfection with miR-19a mimic. Dual-luciferase reporter assay and Western blotting assay revealed that PTEN was a direct target gene of miR-19a, and miR-19a suppressed the expression of PTEN via binding to its 3′-UTR. We further identified that overexpression of miR-19a inhibited the expression of PTEN at the mRNA and protein levels. Moreover, PTEN was highly expressed in H/R H9C2 cells and the apoptosis induced by H/R was associated with the increase in PTEN expression. Importantly, miR-19a mimic significantly increased p-Akt levels under H/R. In conclusion, our findings indicate that miR-19a could protect against H/R-induced cardiomyocyte apoptosis by inhibiting PTEN /PI3K/p-Akt signaling pathway.

Isolariciresinol-9'-O-α-L-arabinofuranoside protects against hydrogen peroxide‑induced apoptosis of human umbilical vein endothelial cells via a PI3K/Akt/Bad‑dependent pathway

Isolariciresinol-9'-O-α-L-arabinofuranoside (MWS‑19) isolated from Pinus massoniana Lamb. Fresh pine needles is the major ingredient of the Songling Xuemaikang capsule therapy used for hypertension. The present study aimed to investigate the effects and underlying mechanisms of MWS‑19 on hydrogen peroxide (H2O2)‑induced apoptosis in human umbilical vein endothelial cells (HUVECs). To investigate the effect of MWS‑19 on apoptosis in HUVECs, an oxidative stress‑induced apoptosis model was established in HUVECs using H2O2, and the present study performed Hoechst 33258 staining and a Cell Counting Kit‑8 (CCK‑8) assay. Furthermore, western blot analysis was also performed to investigate the underlying mechanism of the effects of MWS‑19 on the model. The results demonstrated that MWS‑19 reversed the effects of H2O2 on cell apoptosis at a concentration range of 15.6‑250 µg/ml, with dose‑dependent increases in cell growth. Hoechst staining indicated that 500 µM H2O2 induced HUVEC apoptosis, and MWS‑19 markedly protected HUVECs against apoptosis at 31.3, 62.5 and 125 µg/ml. Furthermore, the protein expression of phosphatidylinositol 3‑kinase (PI3K), phosphorylated‑Akt and Bcl‑2‑associated agonist of cell death (Bad) were increased, and reduced caspase‑3 activation was observed, following treatment with MWS‑19 in H2O2‑treated HUVECs. Additionally, the PI3K inhibitor wortmannin attenuated PI3K/Akt/Bad signaling induced by MWS‑19 treatment and neutralized the effect of MWS‑19 on the growth of HUVECs. In conclusion, the results of the present study indicate that MWS‑19 may protect against H2O2‑induced HUVEC apoptosis via the PI3K/Akt/Bad signaling pathway. MWS‑19 may serve an important role in the prevention of oxidative damage in vascular endothelial cells in hypertension patients.

Exendin-4 attenuates neuronal death via GLP-1R/PI3K/Akt pathway in early brain injury after subarachnoid hemorrhage in rats

Neuronal apoptosis is considered to be a crucial therapeutic target against early brain injury (EBI) after subarachnoid hemorrhage (SAH). Emerging evidence indicates that Exendin-4 (Ex-4), a glucagon-like peptide 1 receptor (GLP-1R) agonist, plays a neuroprotective role in cerebrovascular disease. This study was conducted in order to verify the neuroprotective role of EX-4 in EBI after SAH in rats. The endovascular perforation model of SAH was performed in Sprague-Dawley rats (n = 153). Ex-4 was intraperitoneally injected 1 h after SAH induction in the rats (SAH + Ex-4). To elucidate the underlying molecular mechanism, small interfering ribonucleic acid (siRNA) for GLP-1R and a specific inhibitor of PI3K, LY294002, were injected intracerebroventricularly into SAH + Ex-4 rats before induction of SAH (n = 6 per group). SAH grading evaluation, immunohistochemistry, Western blots, neurobehavioral assessment, and Fluoro-Jade C (FJC) staining experiments were performed. Expression of GLP-1R was significantly increased and mainly expressed in neurons at 24 h after SAH induction. Administration of Ex-4 significantly improved both short- and long-term neurobehavior in SAH + Ex-4 group compared to SAH + Vehicle group after SAH. Ex-4 treatment significantly increased the expression of GLP-1R, PI3K, p-Akt, Bcl-xl, and Bcl-2, while at the same time was found to decrease expression of Bax in the brain. Effects of Ex-4 were reversed by the intervention of GLP-1R siRNA and LY294002 in SAH + Ex-4+GLP-1R siRNA and SAH + Ex-4+LY294002 groups, respectively. In conclusion, the neuroprotective effect of Ex-4 in EBI after SAH was mediated by attenuation of neuronal apoptosis via GLP-1R/PI3K/Akt signaling pathway, therefore EX-4 should be further investigated as a potential therapeutic agent in stroke patients.

Kaempferide Protects against Myocardial Ischemia/Reperfusion Injury through Activation of the PI3K/Akt/GSK-3β Pathway

The aim of this study is to investigate both the efficacy and mechanism of action of kaempferide (Kae) as a therapy for the treatment of cardiovascular disease. A rat model of myocardial ischemia/reperfusion (I/R) injury was established by ligation of the left anterior descending coronary artery for 30 min followed by a 2 h perfusion. In our study, we show that Kae remarkably improved cardiac function, alleviated myocardial injury via a decrease in myocardial enzyme levels, and attenuated myocardial infarct size in a dose-dependent manner. In addition, preconditioning treatment with Kae was found to significantly decrease serum TNF-α, IL-6, C-reactive protein (CRP), MDA, and ROS levels, while it was found to increase serum levels of SOD. Nuclear factor erythroid 2-related factor 2 (Nrf2) and cleaved caspase-3 expression levels were observed to be downregulated, while phospho-Akt (p-Akt) and phospho-glycogen synthase kinase-3β (p-GSK-3β) expression levels were upregulated. However, cotreatment with LY294002 (a PI3K inhibitor) or TDZD-8 (a GSK-3β inhibitor) was found to abolish the above cardioprotective effects observed with the Kae treatment. The data presented in this study provides evidence that Kae attenuates I/R-induced myocardial injury through inhibition of the Nrf2 and cleaved caspase-3 signaling pathways via a PI3K/Akt/GSK 3β-dependent mechanism.

RhGLP-1 (7-36) protects diabetic rats against cerebral ischemia-reperfusion injury via up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD

The present study aimed to explore the neuroprotective effect and possible mechanisms of rhGLP-1 (7–36) against transient ischemia/reperfusion injuries induced by middle cerebral artery occlusion (MCAO) in type 2 diabetic rats. First, diabetic rats were established by a combination of a high-fat diet and low-dose streptozotocin (STZ) (30 mg/kg, intraperitoneally). Second, they were subjected to MCAO for 2 h, then treated with rhGLP-1 (7–36) (10, 20, 40 µg/kg i.p.) at the same time of reperfusion. In the following 3 days, they were injected with rhGLP-1 (7–36) at the same dose and route for three times each day. After 72 h, hypoglycemic effects were assessed by blood glucose changes, and neuroprotective effects were evaluated by neurological deficits, infarct volume and histomorphology. Mechanisms were investigated by detecting the distribution and expression of the nuclear factor erythroid-derived factor 2 related factor 2 (Nrf2) in ischemic brain tissue, the levels of phospho-PI3 kinase (PI3K)/PI3K ratio and heme-oxygenase-1 (HO-l), as well as the activities of superoxide dismutase (SOD) and the contents of malondialdehyde (MDA). Our results showed that rhGLP-1 (7–36) significantly reduced blood glucose and infarction volume, alleviated neurological deficits, enhanced the density of surviving neurons and vascular proliferation. The nuclear positive cells ratio and expression of Nrf2, the levels of P-PI3K/PI3K ratio and HO-l increased, the activities of SOD increased and the contents of MDA decreased. The current results indicated the protective effect of rhGLP-1 (7–36) in diabetic rats following MCAO/R that may be concerned with reducing blood glucose, up-regulating expression of Nrf2/HO-1 and increasing the activities of SOD.

All-trans-retinoic acid-mediated cytoprotection in LLC-PK1 renal epithelial cells is coupled to p-ERK activation in a ROS-independent manner

Although all-trans-retinoic acid (ATRA) provides protection against a variety of conditions in vivo, particularly ischemia, the molecular mechanisms underpinning these effects remain unclear. The present studies were designed to assess potential mechanisms by which ATRA affords cytoprotection against renal toxicants in LLC-PK₁ cells. Pretreatment of LLC-PK₁ cells with ATRA (25 μM) for 24 h afforded cytoprotection against oncotic cell death induced by p-aminophenol (PAP), 2-(glutathion-S-yl)hydroquinone (MGHQ), and iodoacetamide but not against apoptotic cell death induced by cisplatin. Inhibition of protein synthesis with cycloheximide blunted ATRA protection, indicating essential cell survival pathways must be engaged before toxicant exposure to provide cytoprotection. Interestingly, ATRA did not prevent the PAP-induced generation of reactive oxygen species (ROS) nor did it alter glutathione levels. Moreover, ATRA had no significant effect on Nrf2 protein expression, and the Nrf2 inducers sulforaphane and MG132 did not influence ATRA cytoprotection, suggesting cytoprotective pathways beyond those that influence ROS levels contribute to ATRA protection. In contrast, ATRA rapidly (15 min) induced levels of the cellular stress kinases p-ERK and p-AKT at concentrations of ATRA (10 and 25 μM) required for cytoprotection. Consistent with a role for p-ERK in ATRA-mediated cytoprotection, inhibition of p-ERK with PD98059 reduced the ability of ATRA to afford protection against PAP toxicity. Collectively, these data suggest that p-ERK and its downstream targets, independent of ROS and antioxidant signaling, are important contributors to the cytoprotective effects of ATRA against oncotic cell death.

Nogo receptor knockdown and ciliary neurotrophic factor attenuate diabetic retinopathy in streptozotocin-induced diabetic rats

Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM). We investigated whether Nogo receptor (NgR) knockdown and ciliary neurotrophic factor (CNTF) treatment, either alone or in combination, ameliorated diabetic retinopathy (DR) in diabetic rat model. STZ‑induced diabetic rats were administrated for a total of 12 weeks with 3 µM siRNA (5 µl) once every 6 weeks and/or 1 µg CNTF weekly. The retinal tissues were excised. We measured cell number in ganglion cell layer (GCL) using H&E staining and cell apoptosis using TUNEL assay. Bax, Bcl‑2, Caspase‑3, F‑actin, GAP‑43, NgR, RhoA and Rock1 levels were then analyzed by Western blotting, Immunohistochemistry or Real‑time PCR. We found that NgR siRNA or CNTF injection alone significantly increased cell count in GCL in diabetic rats, inhibited ganglion cell apoptosis, elevated Bcl‑2, F‑actin and GAP‑43, and decreased Bax, Caspase‑3, NgR, RhoA and Rock1 levels. Combination treatment further prevented retinal ganglion cell loss, enhanced growth cone cytoskeleton and axonal regeneration, and suppressed NgR/RhoA/Rock1. Our results indicate that combination therapy has therapeutic potential for the treatment of DR.

Antitumoral Effects of D-Fraction from Grifola Frondosa (Maitake) Mushroom in Breast Cancer

D-Fraction is protein-bound β-1,6 and β-1,3 glucans (proteoglucan) extracted from the edible and medicinal mushroom Grifola frondosa (Maitake). The antitumoral effect of D-Fraction has long been exclusively attributed to their immunostimulatory capacity. However, in recent years increasing evidence showed that D-Fraction directly affects the viability of canine and human tumor cells, independent of the immune system. Previously, we have reported that D-Fraction modulates the expression of genes associated with cell proliferation, cell death, migration, invasion, and metastasis in MCF7 human breast cancer cells. Therefore, the purpose of the current study is to investigate if this modulation of gene expression by Maitake D-Fraction really modulates tumor progression. In the present work, we demonstrate for the first time that Maitake D-Fraction is able to act directly on mammary tumor cells, modulating different cellular processes involved in the development and progression of cancer. We demonstrate that D-Fraction decreases cell viability, increases cell adhesion, and reduces the migration and invasion of mammary tumor cells, generating a less aggressive cell behavior. In concordance with these results, we also demonstrate that D-Fraction decreases tumor burden and the number of lung metastases in a murine model of breast cancer.

Glycyrrhetinic acid protects H9c2 cells from oxygen glucose deprivation-induced injury through the PI3K/AKt signaling pathway

Glycyrrhetinic acid (GA) is an ingredient of triterpene saponins found in Gancao (Radix Glycyrrhizae). Here, we investigated the protective effects of GA in H9c2 cells, and explored its possible mechanism of action. Different concentrations of GA were used to treat H9c2 cells under oxygen glucose deprivation. We analyzed cell necrosis and apoptosis using optical microscopy, Hoechst 33342 staining, FITC-annexin V/PI double-staining and lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) and interleukin (IL)-1β assays. Changes in related pro-apoptosis and anti-apoptosis proteins were detected by Western blot. Optical microscopy showed that GA improved cell morphology, including cell shrinkage, cauliflower-like membrane blebbing, and even some cell debris. Meanwhile, GA also ameliorated cell nuclei characteristics such as nucleus size, chromatin condensation and bright staining from Hoechst 33342 staining. GA also lowered the apoptotic rate and the levels of LDH, CK-MB and IL-1β in a dose-dependent manner. Furthermore, GA treatment increased Bcl-2 protein expression and decreased caspase-8 and Bax protein expression, while elevating the Bcl-2/Bax ratio. GA preconditioning increased p-AKt protein expression; however, after adding LY 294002, the p-AKt expression decreased obviously. Our results demonstrated that GA could protect H9c2 cells from apoptosis in a dose-dependent manner, and the potential mechanism might be related to the PI3K/AKt signaling pathway.