Cardio-protective effects of combined l-arginine and insulin: Mechanism and therapeutic actions in myocardial ischemia-reperfusion injury

Research progress on the protective effect of hormones and hormone drugs in myocardial ischemia-reperfusion injury

Ischemic heart disease (IHD) is a condition where the heart muscle does not receive enough blood flow, leading to cardiac dysfunction. Restoring blood flow to the coronary artery is an effective clinical therapy for myocardial ischemia. This strategy helps lower the size of the myocardial infarction and improves the prognosis of patients. Nevertheless, if the disrupted blood flow to the heart muscle is restored within a specific timeframe, it leads to more severe harm to the previously deprived heart tissue. This condition is referred to as myocardial ischemia/reperfusion injury (MIRI). Until now, there is a dearth of efficacious strategies to prevent and manage MIRI. Hormones are specialized substances that are produced directly into the circulation by endocrine organs or tissues in humans and animals, and they have particular effects on the body. Hormonal medications utilize human or animal hormones as their active components, encompassing sex hormones, adrenaline medications, thyroid hormone medications, and others. While several studies have examined the preventive properties of different endocrine hormones, such as estrogen and hormone analogs, on myocardial injury caused by ischemia-reperfusion, there are other hormone analogs whose mechanisms of action remain unexplained and whose safety cannot be assured. The current study is on hormones and hormone medications, elucidating the mechanism of hormone pharmaceuticals and emphasizing the cardioprotective effects of different endocrine hormones. It aims to provide guidance for the therapeutic use of drugs and offer direction for the examination of MIRI in clinical therapy.

Advancing ophthalmic delivery of flurbiprofen via synergistic chiral resolution and ion-pairing strategies

Flurbiprofen (FB), a nonsteroidal anti-inflammatory drug, is widely employed in treating ocular inflammation owing to its remarkable anti-inflammatory effects. However, the racemic nature of its commercially available formulation (Ocufen®) limits the full potential of its therapeutic activity, as the (S)-enantiomer is responsible for the desired anti-inflammatory effects. Additionally, the limited corneal permeability of FB significantly restricts its bioavailability. In this study, we successfully separated the chiral isomers of FB to obtain the highly active (S)-FB. Subsequently, utilizing ion-pairing technology, we coupled (S)-FB with various counter-ions, such as sodium, diethylamine, trimethamine (TMA), and l-arginine, to enhance its ocular bioavailability. A comprehensive evaluation encompassed balanced solubility, octanol-water partition coefficient, corneal permeability, ocular pharmacokinetics, tissue distribution, and in vivo ocular anti-inflammatory activity of each chiral isomer salt. Among the various formulations, S-FBTMA exhibited superior water solubility (about 1-12 mg/ml), lipid solubility (1< lg Pow < 3) and corneal permeability. In comparison to Ocufen®, S-FBTMA demonstrated significantly higher in vivo anti-inflammatory activity and lower ocular irritability (such as conjunctival congestion and tingling). The findings from this research highlight the potential of chiral separation and ion-pair enhanced permeation techniques in providing pharmaceutical enterprises focused on drug development with a valuable avenue for improving therapeutic outcomes.

Kazinol B protects H9c2 cardiomyocytes from hypoxia/reoxygenation-induced cardiac injury by modulating the AKT/AMPK/Nrf2 signalling pathway

CONTEXT

Kazinol B (KB), an isoprenylated flavan derived from Broussonetia kazinoki Sieb. (Moraceae) root, has long been used in folk medicine.

OBJECTIVE

This study examines the protective effects of KB and its underlying mechanisms in hypoxia and reoxygenation (H/R)-induced cardiac injury in H9c2 rat cardiac myoblasts.

MATERIALS AND METHODS

H9c2 cells were incubated with various concentrations of KB (0, 0.3, 1, 3, 10 and 30 μM) for 2 h and then subjected to H/R insults. The protective effects of KB and its underlying mechanisms were explored.

RESULTS

KB significantly elevated cell viability (1 μM, 1.21-fold; 3 μM, 1.36-fold, and 10 μM, 1.47-fold) and suppressed LDH release (1 μM, 0.77-fold; 3 μM, 0.68-fold, and 10 μM, 0.59-fold) in H/R-induced H9c2 cells. Further, 10 μM KB blocked apoptotic cascades, as shown by the Annexin-V/PI (0.41-fold), DNA fragmentation (0.51-fold), caspase-3 (0.52-fold), PARP activation (0.27-fold) and Bax/Bcl-2 expression (0.28-fold) assays. KB (10 μM) downregulated reactive oxygen species production (0.51-fold) and lipid peroxidation (0.48-fold); it upregulated the activities of GSH-Px (2.08-fold) and SOD (1.72-fold). KB (10 μM) induced Nrf2 nuclear accumulation (1.94-fold) and increased ARE promoter activity (2.15-fold), HO-1 expression (3.07-fold), AKT (3.07-fold) and AMPK (3.07-fold) phosphorylation. Nrf2 knockdown via using Nrf2 siRNA abrogated KB-mediated protective effects against H/R insults. Moreover, pharmacological inhibitors of AKT and AMPK also abrogated KB-induced Nrf2 activation and its protective function.

DISCUSSION AND CONCLUSIONS

KB prevented H/R-induced cardiomyocyte injury via modulating the AKT and AMPK-mediated Nrf2 induction. KB might be a promising drug candidate for managing ischemic cardiac disorders.

Endothelium-dependent remote signaling in ischemia and reperfusion: Alterations in the cardiometabolic continuum

Intact endothelial function plays a fundamental role for the maintenance of cardiovascular (CV) health. The endothelium is also involved in remote signaling pathway-mediated protection against ischemia/reperfusion (I/R) injury. However, the transfer of these protective signals into clinical practice has been hampered by the complex metabolic alterations frequently observed in the cardiometabolic continuum, which affect redox balance and inflammatory pathways. Despite recent advances in determining the distinct roles of hyperglycemia, insulin resistance (InR), hyperinsulinemia, and ultimately diabetes mellitus (DM), which define the cardiometabolic continuum, our understanding of how these conditions modulate endothelial signaling remains challenging. It is widely accepted that endothelial cells (ECs) undergo functional changes within the cardiometabolic continuum. Beyond vascular tone and platelet-endothelium interaction, endothelial dysfunction may have profound negative effects on outcome during I/R. In this review, we summarize the current knowledge of the influence of hyperglycemia, InR, hyperinsulinemia, and DM on endothelial function and redox balance, their influence on remote protective signaling pathways, and their impact on potential therapeutic strategies to optimize protective heterocellular signaling.

Astragaloside IV improves angiogenesis under hypoxic conditions by enhancing hypoxia‑inducible factor‑1α SUMOylation

Improving angiogenic capacity under hypoxic conditions is essential for improving the survival of skin grafts, as they often lack the necessary blood supply. The stable expression levels of hypoxia‑inducible factor‑1α (HIF‑1α) in the nucleus directly affect the downstream vascular endothelial growth factor (VEGF) signaling pathway and regulate angiogenesis in a hypoxic environment. Astragaloside IV (AS‑IV), an active component isolated from Astragalus membranaceus, has multiple biological effects including antioxidant and anti‑diabetic effects, and the ability to provide protection from cardiovascular damage. However, the mechanisms underlying these effects have not previously been elucidated. The present study investigated whether AS‑IV promotes angiogenesis via affecting the balance between ubiquitination and small ubiquitin‑related modifier (SUMO) modification of HIF‑1α. The results demonstrated that persistent hypoxia induces changes in expression levels of HIF‑1α protein and significantly increases the proportion of dysplastic blood vessels. Further western blotting experiments showed that rapid attenuation and delayed compensation of SUMO1 activity is one of the reasons for the initial increase then decrease in HIF‑1α levels. SUMO1 overexpression stabilized the presence of HIF‑1α in the nucleus and decreased the extent of abnormal blood vessel morphology observed following hypoxia. AS‑IV induces vascular endothelial cells to continuously produce SUMO1, stabilizes the HIF‑1α/VEGF pathway and improves angiogenesis in hypoxic conditions. In summary, the present study confirmed that AS‑IV stimulates vascular endothelial cells to continuously resupply SUMO1, stabilizes the presence of HIF‑1α protein and improves angiogenesis in adverse hypoxic conditions, which may improve the success rate of flap graft surgery following trauma or burn.

Salvia miltiorrhiza in diabetes: A review of its pharmacology, phytochemistry, and safety

BACKGROUND

Salvia miltiorrhiza (SM), one of the frequently used herbs in traditional Chinese medicine (TCM), has now attracted rising interests for a possible alternative in the management of diabetes. This review is aimed to providing a comprehensive perspective of SM in phytochemical constituents, pharmacological activities against diabetes and its complications, and safety.

METHODS

A comprehensive search of published literatures was conducted to locate original publications pertaining to SM and diabetes till the end of 2017 using PubMed, China National Knowledge Infrastructure, National Science and Technology Library, China Science and Technology Journal Database, and Web of Science database. The main inquiry was used for the presence of the following keywords in various combinations in the titles and abstracts: Salvia miltiorrhiza, diabetes, obesity, phytochemistry, pharmacology, and safety. About 200 research papers and reviews were consulted.

RESULTS

SM exhibited anti-diabetic activities by treating macro- and micro-vascular diseases in preclinical experiments and clinical trials through an improvement of redox homeostasis and inhibition of apoptosis and inflammation via the regulation of Wnt/β-catenin, TSP-1/TGF-β1/STAT3, JNK/PI3K/Akt, kinin B2 receptor-Akt-GSK-3β, AMPKβ/PGC-1α/Sirt3, Akt/AMPK, TXNIP/NLRP3, TGF-β1/NF-κB, mineralocorticoid receptor/Na⁺/K⁺-ATPase, AGEs/RAGE, Nrf2/Keap1, CaMKKβ/AMPK, AMPK/ACC, IRS-1/PI3K signaling pathways, and modulation of K⁺-Ca²⁺ channels, as well as influence of VEGF, NOS, AGEs, PPAR expression and hIAPP aggregation. The antidiabetic effects of this herb may be related to its TCM characters of improving blood circulation and reliving blood stasis. The main ingredients of SM included salvianolic acids and diterpenoid tanshinones, which have been well studied in the diabetic animals. Acute and subacute toxicity studies supported the notion that SM is well tolerated.

CONCLUSION

SM may offer a new strategy for prevention and treatment of diabetes and its complications that stimulates extensive research into identifying potential anti-diabetic compounds and fractions as well as exploring the underlying mechanisms of this herb. Further scientific evidences are still required from well-designed preclinical experiments and clinical trials on its anti-diabetic effects and safety.

Trichosanthis Pericarpium Aqueous Extract Protects H9c2 Cardiomyocytes from Hypoxia/Reoxygenation Injury by Regulating PI3K/Akt/NO Pathway

Trichosanthis Pericarpium (TP) is a traditional Chinese medicine for treating cardiovascular diseases. In this study, we investigated the effects of TP aqueous extract (TPAE) on hypoxia/reoxygenation (H/R) induced injury in H9c2 cardiomyocytes and explored the underlying mechanisms. H9c2 cells were cultured under the hypoxia condition induced by sodium hydrosulfite for 30 min and reoxygenated for 4 h. Cell viability was measured by MTT assay. The amounts of LDH, NO, eNOS, and iNOS were tested by ELISA kits. Apoptotic rate was detected by Annexin V-FITC/PI staining. QRT-PCR was performed to analyze the relative mRNA expression of Akt, Bcl-2, Bax, eNOS, and iNOS. Western blotting was used to detect the expression of key members in the PI3K/Akt pathway. Results showed that the pretreatment of TPAE remarkably enhanced cell viability and decreased apoptosis induced by H/R. Moreover, TPAE decreased the release of LDH and expression of iNOS. In addition, TPAE increased NO production and Bcl-2/Bax ratio. Furthermore, the mRNA and protein expression of p-Akt and eNOS were activated by TPAE pretreatment. On the contrary, a specific inhibitor of PI3K, LY294002 not only inhibited TPAE-induced p-Akt/eNOS upregulation but alleviated its anti-apoptotic effects. In conclusion, results indicated that TPAE protected against H/R injury in cardiomyocytes, which consequently activated the PI3K/Akt/NO signaling pathway.

Cardioprotective effects of monocyte locomotion inhibitory factor on myocardial ischemic injury by targeting vimentin

Monocyte locomotion inhibitory factor (MLIF), a heat-stable pentapeptide produced by Entamoeba histolytica, has anti-inflammatory function and protective effect on ischemic stroke. In this study, we evaluated the effect of MLIF on myocardial ischemia. Mice were subjected to ischemia/reperfusion by occlusion of the left anterior descending artery (LAD). After sacrifice, the serum concentrations of cardiac troponin I (cTnI), creatine kinase (CK), lactate dehydrogenase (LDH) as well as the heart infarct size were measured. HE and TUNEL staining were used to observe the pathological damage and the apoptotic cells. For in vitro study, the oxygen-glucose deprivation(OGD) model was established in H9c2 cells. MTT assay and flow cytometry assay were performed to evaluate cell viability and apoptosis. The expression of JNK and caspase 3 was assessed by western blot analysis. Pull-down assay was used to detect the specific binding protein of MLIF in myocardial cells. MLIF significantly reduced the infarct size, and the cTnI, CK and LDH levels, amelioratived pathological damage and reduced the apopotosis compared with the myocardial I/R model group. MLIF improved cell survival and inhibited apoptosis and necrosis by inhibiting the p-JNK and cleaved caspase3 expression. Furthermore, the binding protein of MLIF in myocardial cells was vimentin. Inhibition of vimentin expression by withaferin A or vimentin siRNA repressed the protective effects of MLIF in OGD-provoked H9c2 cells. Taken together, our results demonstrate that the cardioprotective effects of MLIF on myocardial ischemia injury are related to reductions in the inflammatory response and apoptosis by targeting vimentin.