Low-dose radiation prevents type 1 diabetes-induced cardiomyopathy via activation of AKT mediated anti-apoptotic and anti-oxidant effects

Paederia foetida Ameliorates Diabetic Cardiomyopathy in Rats Models by Suppressing Apoptosis

Diabetes mellitus is one of the most prevalent global public health issues associated with a higher risk of cardiovascular diseases, contributing to morbidity and mortality. Research has demonstrated that elevated reactive oxygen species (ROS) generation in diabetes can trigger apoptosis, exacerbating diabetic cardiomyopathy (DCM). This study investigates the cardioprotective effects of Paederia foetida in rats’ models of type 2 diabetes induced by a high-fat diet (HFD) and streptozotocin (STZ) treatment. The diabetic model was established in Sprague Dawley rats by intraperitoneal injection of streptozotocin (STZ, 40 mg/kg). Sprague Dawley rats were treated with varied concentrations of standardized extract of P. foetida (50 mg/kg and 100 mg/kg), administered orally once daily for four weeks. Standardized extract from P. foetida has a range of therapeutic potential, including anti-inflammatory, antioxidant, and anti-diabetic properties. The common metabolic disorder indices and myocardial apoptosis were investigated. The findings from this study demonstrated increased expression of Bcl-2 and decreased expression of Bcl-2 Associated X-protein BAX as indicated by IRS scoring in cardiomyocytes, suggesting that P. foetida has a significant protective effect on diabetic cardiomyopathy by decreasing apoptosis. Increased Bcl-2 and decreased BAX levels may be related to regulating oxidative stress and mitochondrial pathways involving myocardial apoptosis. P. foetida extract could be a potential intervention for attenuating cardiomyopathy in diabetes mellitus.

Low-Dose Radiation Reduces Doxorubicin-Induced Myocardial Injury Through Mitochondrial Pathways

The use of doxorubicin (DOX) as an anthraquinone antineoplastic agent is limited due to its cardiotoxicity. Our previous study suggested that low-dose radiation (LDR) could mitigate the cardiotoxicity induced by DOX via suppressing oxidative stress and cell apoptosis. However, the molecular targets and protective mechanism of LDR are not understood. In the present study, we sought to investigate the mechanisms underlying LDR's cardioprotection. Balb/c mice were randomly divided into four groups: Control group (no treatment), DOX group, LDR group (75 mGy), and LDR-72 h-DOX group (LDR pretreatment followed by intraperitoneal injection of DOX). Electron microscopy, PCR, and Western blot analyses indicated that LDR pretreatment mitigated changes in mitochondrial morphology caused by DOX, upregulated activity of mitochondrial complexes, and restored ATP levels in cardiomyocytes that were decreased by DOX. Whole genome microarray and PCR analyses showed that mitochondrial-related genes were altered by LDR pretreatment. Thus, our study showed that LDR can protect cardiomyocytes against DOX through improving mitochondrial function and increasing ATP production. This research could inform DOX chemotherapy strategies and provide new insight into the molecule mechanisms underlying the cardioprotective effects of LDR.

Low-Dose Radiation Affects Cardiovascular Disease Risk in Human Aortic Endothelial Cells by Altering Gene Expression under Normal and Diabetic Conditions

High doses of ionizing radiation can cause cardiovascular diseases (CVDs); however, the effects of <100 mGy radiation on CVD remain underreported. Endothelial cells (ECs) play major roles in cardiovascular health and disease, and their function is reduced by stimuli such as chronic disease, metabolic disorders, and smoking. However, whether exposure to low-dose radiation results in the disruption of similar molecular mechanisms in ECs under diabetic and non-diabetic states remains largely unknown; we aimed to address this gap in knowledge through the molecular and functional characterization of primary human aortic endothelial cells (HAECs) derived from patients with type 2 diabetes (T2D-HAECs) and normal HAECs in response to low-dose radiation. To address these limitations, we performed RNA sequencing on HAECs and T2D-HAECs following exposure to 100 mGy of ionizing radiation and examined the transcriptome changes associated with the low-dose radiation. Compared with that in the non-irradiation group, low-dose irradiation induced 243 differentially expressed genes (DEGs) (133 down-regulated and 110 up-regulated) in HAECs and 378 DEGs (195 down-regulated and 183 up-regulated) in T2D-HAECs. We also discovered a significant association between the DEGs and the interferon (IFN)-I signaling pathway, which is associated with CVD by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, protein−protein network analysis, and module analysis. Our findings demonstrate the potential impact of low-dose radiation on EC functions that are related to the risk of CVD.

Recombinant human endostatin combined with radiotherapy promotes cardiomyocyte apoptosis in rats via TGFβ1/Smads/CTGF signaling pathway

PURPOSE

The aim of the present study was to investigate the efficacy of recombinant human endostatin (ES) (rh-ES) combined with radiation on rat cardiomyocyte apoptosis and the regulatory mechanism of transforming growth factor beta1 (TGF-β1)/Sma and Mad-related protein 3 (Smad3)/connective tissue growth factor (CTGF) signaling.

METHOD

The primary cardiomyocytes were isolated from neonatal Sprague-Dawley rats for culture in vitro and divided into blank control group (without treatment), 10 Gy radiation + siTGF-β1 siRNA (gene silencing) group, ES + siTGF-β1 siRNA group, and 10 Gy radiation + ES + siTGF-β1 siRNA group. Methyl thiazolyl tetrazolium assay was used to calculate the half-maximal inhibitory concentration (IC50) of rh-ES on cardiomyocytes. Adenoviral vector was constructed for virus packaging to silence TGF-β1 expression in cardiomyocytes. Quantitative real-time polymerase chain reaction and Western blot were carried out to analyze TGF-β1, Smad2, Smad3 and CTGF expression at both gene and protein levels. Flow cytometry and electron microscope were used to examine cell apoptosis.

RESULTS

ES had a dose-dependent inhibitory effect on the proliferation of primary rat cardiomyocytes. ES combined with radiotherapy significantly inhibited cardiomyocyte proliferation and promoted cell apoptosis (P < 0.01). The gene and protein expression of TGF-β1, Smad2, Smad3 and CTGF were significantly up-regulated in primary cardiomyocytes transfected with TGF-β1 gene (P < 0.05).

CONCLUSION

The combination therapy with rh-ES and radiation can promote cardiomyocyte apoptosis and aggravate myocardial cell damage via TGF-β1/Smad3/CTGF signaling pathway.

SET8, a novel regulator to ameliorate vascular calcification via activating PI3K/Akt mediated anti-apoptotic effects

Previous studies have shown that the apoptosis of vascular smooth muscle cells (VSMCs) underlies the mechanism of pathological calcification in patients with chronic kidney disease (CKD). SET domain-containing protein 8 (SET8) is an efficient protein that modulates apoptosis in hepatocellular carcinoma cells, esophageal squamous cells, and neuronal cells by regulating pathological processes, such as cell cycle progression and transcription regulation. However, whether SET8 is involved in high phosphorus-induced vascular calcification by mediating apoptosis remains unclear. Here, we report that SET8 is located both in the nucleus and cytoplasm and is significantly downregulated in calcification models. SET8 deficiency promoted apoptosis of VSMCs, as indicated by the increased Bax/Bcl-2 and cleaved caspase-3/total caspase-3 ratios. Mechanistically, the PI3K/Akt pathway was mediated by SET8, and inhibition of the PI3K/Akt signaling pathway by administering LY294002 or transfecting the Akt phosphorylation-inactivated mutation plasmid increased apoptosis and calcification. Akt phosphorylation constitutively activated mutations can reduce the apoptosis and calcification of VSMCs. Furthermore, exogenous overexpression of SET8 reversed the effect of PI3K/Akt inhibition on VSMC apoptosis and calcification. In summary, our research suggests that SET8 overexpression ameliorates high phosphorus-induced calcification of VSMCs by activating PI3K/Akt mediated anti-apoptotic effects.

Low Dose Ionising Radiation-Induced Hormesis: Therapeutic Implications to Human Health

The concept of radiation-induced hormesis, whereby a low dose is beneficial and a high dose is detrimental, has been gaining attention in the fields of molecular biology, environmental toxicology and radiation biology. There is a growing body of literature that recognises the importance of hormetic dose response not only in the radiation field, but also with molecular agents. However, there is continuing debate on the magnitude and mechanism of radiation hormetic dose response, which could make further contributions, as a research tool, to science and perhaps eventually to public health due to potential therapeutic benefits for society. The biological phenomena of low dose ionising radiation (LDIR) includes bystander effects, adaptive response, hypersensitivity, radioresistance and genomic instability. In this review, the beneficial and the detrimental effects of LDIR-induced hormesis are explored, together with an overview of its underlying cellular and molecular mechanisms that may potentially provide an insight to the therapeutic implications to human health in the future.

Organ-Specific Effects of Low Dose Radiation Exposure: A Comprehensive Review

Ionizing radiation (IR) is a high-energy radiation whose biological effects depend on the irradiation doses. Low-dose radiation (LDR) is delivered during medical diagnoses or by an exposure to radioactive elements and has been linked to the occurrence of chronic diseases, such as leukemia and cardiovascular diseases. Though epidemiological research is indispensable for predicting and dealing with LDR-induced abnormalities in individuals exposed to LDR, little is known about epidemiological markers of LDR exposure. Moreover, difference in the LDR-induced molecular events in each organ has been an obstacle to a thorough investigation of the LDR effects and a validation of the experimental results in in vivo models. In this review, we summarized the recent reports on LDR-induced risk of organ-specifically arranged the alterations for a comprehensive understanding of the biological effects of LDR. We suggested that LDR basically caused the accumulation of DNA damages, controlled systemic immune systems, induced oxidative damages on peripheral organs, and even benefited the viability in some organs. Furthermore, we concluded that understanding of organ-specific responses and the biological markers involved in the responses is needed to investigate the precise biological effects of LDR.

Effective Doses of Ionizing Radiation during Therapeutic Peat Mud Treatment from a Deposit in the Knyszyn Forest (Northeastern Poland)

Radioactivity measurements of 61 therapeutic peat mud samples from the Podsokoldy deposits, near Suprasl, were performed using gamma spectrometry. The authors identified the presence of 13 isotopes with the arithmetic mean of activity (in Bq kg^-1): ¹³⁷Cs-7, ⁴⁰K-24, ²⁰⁸Tl-1, ²¹²Bi-3, ²¹²Pb-2, ²²⁸Ac-2, ²¹⁰Pb-33, ²¹⁴Bi-11, ²¹⁴Pb-11, ²²⁶Ra-53, ²³⁴Th-47. The effective dose obtained during treatment with 15 peat mud baths (lasting 30 min) was 0.078 μSv. Use of peat mud compresses in the same number and period of exposure to the entire body surface caused absorption of a dose of 0.153 μSv. The authors discuss the probability of tissue radiation from isotopes present in the peat mud. In light of radiobiological knowledge, the therapeutic effect of ionizing radiation during peat mud therapy appears to be very unlikely.

Gamma radiation improves AD pathogenesis in APP/PS1 mouse model by potentiating insulin sensitivity

Alzheimer's disease (AD) is the largest unmet medical complication. The devastation caused by the disease can be assumed from the disease symptoms like speech impairment, loss of self-awareness, acute memory loss etc. The individuals suffering from AD completely depend on caregivers and have to bear the high cost of treatment which increases the socio-economic burden on the society. Recent studies have shown that radiation exposure can have therapeutic effects when given in suitable amount for a specific time period. Therefore, we investigated the role of gamma irradiation in AD pathogenesis. The effect of radiation on amelioration of disease progression was studied in AD transgenic mice model (APP/PS1). Our in-vivo studies using APP/PS1 mice demonstrated that a single dose of 4.0 Gy gamma irradiation improves AD associated behavioral impairment. Radiation exposure also increased the level of anti-oxidant enzymes and reduced the astrocyte activation in the brain of APP/PS1 mice. A significant reduction was observed in AD associated proteins (APP, pTau, BACE) and neurofibrillary tangle formations (NFTs). Exposure to a single dose of 4 Gy gamma radiation also increased glucose metabolic functionality in AD transgenic mouse model. The kinases involved in insulin signaling such as GSK, ERK and JNK were also found to be modulated. However, an increased level of GSK3β (ser 9) was observed, which could be responsible for downregulating ERK and JNK phosphorylation. This resulted in a decrease in neurofibrillary tangle formations and amyloid deposition. The reduced hyperphosphorylation of Tau can be attributed to the increased level of GSK3β (ser 9) downregulating ERK and JNK phosphorylation. Thus, a single dose of 4 Gy gamma irradiation was found to have therapeutic benefits in treating AD via potentiating insulin signaling in APP/PS1 transgenic mice.

Rg1 protects H9C2 cells from high glucose-/palmitate-induced injury via activation of AKT/GSK-3β/Nrf2 pathway

Our previous studies have assessed ginsenoside Rg1 (Rg1)‐mediated protection in a type 1 diabetes rat model. To uncover the mechanism through which Rg1 protects against cardiac injury induced by diabetes, we mimicked diabetic conditions by culturing H9C2 cells in high glucose/palmitate. Rg1 had no toxic effect, and it alleviated the high glucose/palmitate damage in a dose‐dependent manner, as indicated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay and lactate dehydrogenase release to the culture medium. Rg1 prevented high glucose/palmitate‐induced cell apoptosis, assessed using cleaved caspase‐3 and terminal deoxynucleotidyl transferase dUTP nick end labelling staining. Rg1 also reduced high glucose‐/palmitate‐induced reactive oxygen species formation and increased intracellular antioxidant enzyme activity. We found that Rg1 activates protein kinase B (AKT)/glycogen synthase kinase‐3 (GSK‐3β) pathway and antioxidant nuclear factor erythroid 2‐related factor 2 (Nrf2) pathway, indicated by increased phosphorylation of AKT and GSK‐3β, and nuclear translocation of Nrf2. We used phosphatidylinositol‐3‐kinase inhibitor Ly294002 to block the activation of the AKT/GSK‐3β pathway and found that it partially reversed the protection by Rg1 and decreased Nrf2 pathway activation. The results suggest that Rg1 exerts a protective effect against high glucose and palmitate damage that is partially AKT/GSK‐3β/Nrf2‐mediated. Further studies are required to validate these findings using primary cardiomyocytes and animal models of diabetes.

Can We Prevent Mitochondrial Dysfunction and Diabetic Cardiomyopathy in Type 1 Diabetes Mellitus? Pathophysiology and Treatment Options

Type 1 diabetes mellitus is a disease involving changes to energy metabolism. Chronic hyperglycemia is a major cause of diabetes complications. Hyperglycemia induces mechanisms that generate the excessive production of reactive oxygen species, leading to the development of oxidative stress. Studies with animal models have indicated the involvement of mitochondrial dysfunction in the pathogenesis of diabetic cardiomyopathy. In the current review, we aimed to collect scientific reports linking disorders in mitochondrial functioning with the development of diabetic cardiomyopathy in type 1 diabetes mellitus. We also aimed to present therapeutic approaches counteracting the development of mitochondrial dysfunction and diabetic cardiomyopathy in type 1 diabetes mellitus.

Radon Therapy for Autoimmune Diseases Pemphigus and Diabetes: 2 Case Reports

We report on the application of radon therapy to relieve the suffering of 2 patients with autoimmune diseases, one with pemphigus with an old myocardial infarction and diabetes mellitus and the other with type I diabetes. We include a lengthy discussion of the biological mechanisms that we believe produced the observed benefits. During the 6 to 9 months of the treatments, the marker values decreased to the upper limit of their normal ranges and the symptoms of the diseases were alleviated. Disorders of Th1/Th2 balance are implicated in the onset of many diseases, including autoimmune diseases. Our decision to give radon (222Rn) therapy to these patients was based on the results of 2 similar case reports and our earlier mouse experiments, which indicated that low doses of radiation induce regulatory T cells. Regulatory T cells regulate the T helper 1 cell and the T helper 2 cell balance. There are more than 80 different autoimmune diseases that are treated with anti-inflammatory agents or immune-suppressing drugs because the exact causes of these diseases and the cures are unknown. These and other case reports indicate that proper radon therapy is an effective treatment. We urge physicians to consider radon as a standard therapy for refractory autoimmune diseases.

Liraglutide, a glucagon-like peptide-1 analog, inhibits high glucose-induced oxidative stress and apoptosis in neonatal rat cardiomyocytes

Cardiomyocyte apoptosis serves an important role in diabetic cardiomyopathy. Liraglutide, a glucagon-like peptide-1 analog, has been indicated to exert a cardioprotective effect. However, the role of liraglutide on cardiomyocyte apoptosis in hyperglycemia is not fully understood. The aim of the current study was to assess whether liraglutide protects against high glucose (HG)-induced cardiomyocyte apoptosis in vitro. Sprague-Dawley neonatal rat cardiomyocytes were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 or 25 mmol/l D-glucose or 5.5 mmol/l D-glucose + 19.5 mmol/l mannitol, in the presence or absence of liraglutide (10 or 100 nmol/l). Cell viability was assessed via an MTT assay and early apoptosis rates were assessed via flow cytometry. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in cell supernatants were measured. Bcl-2 associated X (Bax), B-cell lymphoma-2 (Bcl-2) and cleaved/full caspase-3 protein levels were determined via western blotting. The results revealed that liraglutide effectively inhibited the HG-induced increase in early apoptosis and MDA content and markedly increased SOD activity. Furthermore, liraglutide markedly inhibited the HG-induced increase in Bax and cleaved caspase-3 protein expression, and upregulated the expression of Bcl-2. The present study demonstrated that liraglutide suppressed HG-induced oxidative stress and cardiomyocyte apoptosis. Thus, the anti-apoptotic actions of liraglutide may be attributable, in part, to the inhibition of Bax, the inhibition of caspase-3 activation and the upregualtion of Bcl-2.

Research Progress on the Biological Effects of Low-Dose Radiation in China

Human are exposed to ionizing radiation from natural and artificial sources, which consequently poses a possible risk to human health. However, accumulating evidence indicates that the biological effects of low-dose radiation (LDR) are different from those of high-dose radiation (HDR). Low-dose radiation–induced hormesis has been extensively observed in different biological systems, including immunological and hematopoietic systems. Adaptive responses in response to LDR that can induce cellular resistance to genotoxic effects from subsequent exposure to HDR have also been described and researched. Bystander effects, another type of biological effect induced by LDR, have been shown to widely occur in many cell types. Furthermore, the influence of LDR-induced biological effects on certain diseases, such as cancer and diabetes, has also attracted the interest of researchers. Many studies have suggested that LDR has the potential antitumor and antidiabetic complications effects. In addition, the researches on whether LDR could induce stochastic effects were also debated. Studies on the biological effects of LDR in China started in 1970s and considerable progress has been made since. In the present article, we provide an overview of the research progress on the biological effects of LDR in China.

Low-dose ionizing radiation alleviates Aβ42-induced cell death via regulating AKT and p38 pathways in Drosophila Alzheimer's disease models

Ionizing radiation is widely used in medicine and is valuable in both the diagnosis and treatment of many diseases. However, its health effects are ambiguous. Here, we report that low-dose ionizing radiation has beneficial effects in human amyloid-β42 (Aβ42)-expressing Drosophila Alzheimer's disease (AD) models. Ionizing radiation at a dose of 0.05 Gy suppressed AD-like phenotypes, including developmental defects and locomotive dysfunction, but did not alter the decreased survival rates and longevity of Aβ42-expressing flies. The same dose of γ-irradiation reduced Aβ42-induced cell death in Drosophila AD models through downregulation of head involution defective (hid), which encodes a protein that activates caspases. However, 4 Gy of γ-irradiation increased Aβ42-induced cell death without modulating pro-apoptotic genes grim, reaper and hid. The AKT signaling pathway, which was suppressed in Drosophila AD models, was activated by either 0.05 or 4 Gy γ-irradiation. Interestingly, p38 mitogen-activated protein-kinase (MAPK) activity was inhibited by exposure to 0.05 Gy γ-irradiation but enhanced by exposure to 4 Gy in Aβ42-expressing flies. In addition, overexpression of phosphatase and tensin homolog (PTEN), a negative regulator of the AKT signaling pathway, or a null mutant of AKT strongly suppressed the beneficial effects of low-dose ionizing radiation in Aβ42-expressing flies. These results indicate that low-dose ionizing radiation suppresses Aβ42-induced cell death through regulation of the AKT and p38 MAPK signaling pathways, suggesting that low-dose ionizing radiation has hormetic effects on the pathogenesis of Aβ42-associated AD.

Summary: Low-dose ionizing radiation can reduce cell death by regulating AKT/p38 signaling pathway and improve Aβ42-induced symptoms in Drosophila Alzheimer's disease, suggesting that low-dose ionizing radiation may be applicable for treatment.

Re-evaluation of the linear no-threshold (LNT) model using new paradigms and modern molecular studies

The linear no-threshold (LNT) model is currently used to estimate low dose radiation (LDR) induced health risks. This model lacks safety thresholds and postulates that health risks caused by ionizing radiation is directly proportional to dose. Therefore even the smallest radiation dose has the potential to cause an increase in cancer risk. Advances in LDR biology and cell molecular techniques demonstrate that the LNT model does not appropriately reflect the biology or the health effects at the low dose range. The main pitfall of the LNT model is due to the extrapolation of mutation and DNA damage studies that were conducted at high radiation doses delivered at a high dose-rate. These studies formed the basis of several outdated paradigms that are either incorrect or do not hold for LDR doses. Thus, the goal of this review is to summarize the modern cellular and molecular literature in LDR biology and provide new paradigms that better represent the biological effects in the low dose range. We demonstrate that LDR activates a variety of cellular defense mechanisms including DNA repair systems, programmed cell death (apoptosis), cell cycle arrest, senescence, adaptive memory, bystander effects, epigenetics, immune stimulation, and tumor suppression. The evidence presented in this review reveals that there are minimal health risks (cancer) with LDR exposure, and that a dose higher than some threshold value is necessary to achieve the harmful effects classically observed with high doses of radiation. Knowledge gained from this review can help the radiation protection community in making informed decisions regarding radiation policy and limits.

The RhoA/ROCK pathway mediates high glucose-induced cardiomyocyte apoptosis via oxidative stress, JNK, and p38MAPK pathways

AIMS

To understand the roles of the RhoA/ROCK and mitogen-activated protein kinase (MAPK) pathways in high glucose (HG)-induced apoptosis and oxidative stress in cardiomyocytes.

MATERIALS AND METHODS

Neonatal rat cardiomyocytes were cultured in Dulbecco's modified Eagle's medium, supplemented with 5.5 or 30 mmol/L D-glucose, in the presence or absence of fasudil (50 or 100 μM), SB203580, SP600125, or PD98059 (10 μM, respectively). The percentage of early apoptotic cardiomyocytes was evaluated using flow cytometry. The superoxide dismutase activity and malondialdehyde contents in the cellular supernatants were measured. The Bax and Bcl-2 mRNA levels were determined by quantitative real-time PCR. Phosphorylation of myosin phosphatase target subunit 1 (MYPT1), p38MAPK, JNK, and ERK as well as the protein levels of Bax, Bcl-2, and cleaved caspase-3 was analysed by Western blot.

RESULTS

Fasudil, SB203580, and SP600125 effectively inhibited the HG-induced early apoptosis increase and decreased Bax mRNA expression, the Bax/Bcl-2 protein expression ratio, and cleaved caspase-3 protein levels in the cardiomyocytes; this was accompanied by upregulation of the Bcl-2 mRNA. Moreover, fasudil markedly increased the superoxide dismutase activity level and suppressed the elevation in HG-induced malondialdehyde content and the phosphorylation of MYPT1, p38MAPK and JNK.

CONCLUSIONS

The RhoA/ROCK pathway mediates HG-induced cardiomyocyte apoptosis via oxidative stress and activation of p38MAPK and JNK in neonatal rats in vitro. Fasudil effectively ameliorates HG-induced cardiomyocyte apoptosis by suppressing oxidative stress and the p38MAPK and JNK pathways.

Fibroblast growth factor-21 prevents diabetic cardiomyopathy via AMPK-mediated antioxidation and lipid-lowering effects in the heart

Our previous studies showed that both exogenous and endogenous FGF21 inhibited cardiac apoptosis at the early stage of type 1 diabetes. Whether FGF21 induces preventive effect on type 2 diabetes-induced cardiomyopathy was investigated in the present study. High-fat-diet/streptozotocin-induced type 2 diabetes was established in both wild-type (WT) and FGF21-knockout (FGF21-KO) mice followed by treating with FGF21 for 4 months. Diabetic cardiomyopathy (DCM) was diagnosed by significant cardiac dysfunction, remodeling, and cardiac lipid accumulation associated with increased apoptosis, inflammation, and oxidative stress, which was aggravated in FGF21-KO mice. However, the cardiac damage above was prevented by administration of FGF21. Further studies demonstrated that the metabolic regulating effect of FGF21 is not enough, contributing to FGF21-induced significant cardiac protection under diabetic conditions. Therefore, other protective mechanisms must exist. The in vivo cardiac damage was mimicked in primary neonatal or adult mouse cardiomyocytes treated with HG/Pal, which was inhibited by FGF21 treatment. Knockdown of AMPKα1/2, AKT2, or NRF2 with their siRNAs revealed that FGF21 protected cardiomyocytes from HG/Pal partially via upregulating AMPK–AKT2–NRF2-mediated antioxidative pathway. Additionally, knockdown of AMPK suppressed fatty acid β-oxidation via inhibition of ACC–CPT-1 pathway. And, inhibition of fatty acid β-oxidation partially blocked FGF21-induced protection in cardiomyocytes. Further, in vitro and in vivo studies indicated that FGF21-induced cardiac protection against type 2 diabetes was mainly attributed to lipotoxicity rather than glucose toxicity. These results demonstrate that FGF21 functions physiologically and pharmacologically to prevent type 2 diabetic lipotoxicity-induced cardiomyopathy through activation of both AMPK–AKT2–NRF2-mediated antioxidative pathway and AMPK–ACC–CPT-1-mediated lipid-lowering effect in the heart.

Low-Dose Radiation Promotes Dendritic Cell Migration and IL-12 Production via the ATM/NF-KappaB Pathway

For dendritic cells (DCs) to initiate an immune response, their ability to migrate and to produce interleukin-12 (IL-12) is crucial. It has been previously shown that low-dose radiation (LDR) promoted IL-12 production by DCs, resulting in increased DC activity that contributed to LDR hormesis in the immune system. However, the molecular mechanism of LDR-induced IL-12 production, as well as the effect of LDR on DC migration capacity require further elucidation. Using the JAWSII immortalized mouse dendritic cell line, we showed that in vitro X-ray irradiation (0.2 Gy) of DCs significantly increased DC migration and IL-12 production, and upregulated CCR7. The neutralizing antibody against CCR7 has been shown to abolish LDR-enhanced DC migration, demonstrating that CCR7 mediates LDR-promoting DC migration. We identified nuclear factor kappaB (NF-κB) as the central signaling pathway that mediated LDR-enhanced expression of IL-12 and CCR7 based on findings that 0.2 Gy X-ray irradiation activated NF-κB, showing increased nuclear p65 translocation and NF-κB DNA-binding activity, while an NF-κB inhibitor blocked LDR-enhanced expression of IL-12 and CCR7, as well as DC migration. Finally, we demonstrated that 0.2 Gy X-ray irradiation promoted ATM phosphorylation and reactive oxygen species generation; however, only the ATM inhibitor abolished the LDR-induced NF-κB-mediated expression of IL-12 and CCR7. Altogether, our data show that exposure to LDR resulted in a hormetic effect on DCs regarding CCR7-mediated migration and IL-12 production by activating the ATM/NF-κB pathway.

Omega-3 polyunsaturated fatty acids prevent murine dilated cardiomyopathy by reducing oxidative stress and cardiomyocyte apoptosis

Mice that lacked manganese-superoxide dismutase (Mn-SOD) activity exhibited the typical pathology of dilated cardiomyopathy (DCM). The aim of the present study was to investigate the effect of supplementation with omega-3 polyunsaturated fatty acids (n-3 PUFA) on heart function and oxidative stress biomarkers in mice with DCM. In the present study, heart/muscle-specific Mn-SOD-deficient mice (H/M-Sod2^-/-) were treated with n-3 PUFA (30 mg/kg/day) for 10 weeks, and the reactive oxygen species (ROS) production in their heart mitochondria and cardiac function was subsequently assessed. n-3 PUFA treatment diminished ROS production and suppressed the progression of cardiac dysfunction. Furthermore, n-3 PUFA treatment effectively reversed the cardiac dysfunction and dilatation observed in symptomatic H/M-Sod2^-/- mice. Notably, n-3 PUFA treatment ameliorated a molecular defect in connexin 43. Hematoxylin-eosin staining indicated that the phenotype of DCM was also ameliorated following n-3 PUFA treatment. Furthermore, echocardiography demonstrated that cardiac function was significantly improved in the mice treated with n-3 PUFA (P<0.05). Meanwhile, pre-treatment with n-3 PUFA significantly decreased cardiomyocyte apoptosis (P<0.001). In conclusion, n-3 PUFA treatment is able to prevent murine DCM, primarily by reducing ROS production and improving myocardial apoptosis. Therefore, the impairment of ROS production is proposed as a potential therapy for DCM.

Different Sequences of Fractionated Low-Dose Proton and Single Iron-Radiation-Induced Divergent Biological Responses in the Heart

Deep-space travel presents risks of exposure to ionizing radiation composed of a spectrum of low-fluence protons (¹H) and high-charge and energy (HZE) iron nuclei (e.g., ⁵⁶Fe). When exposed to galactic cosmic rays, each cell in the body may be traversed by ¹H every 3-4 days and HZE nuclei every 3-4 months. The effects of low-dose sequential fractionated ¹H or HZE on the heart are unknown. In this animal model of simulated ionizing radiation, middle-aged (8-9 months old) male C57BL/6NT mice were exposed to radiation as follows: group 1, nonirradiated controls; group 2, three fractionated doses of 17 cGy ¹H every other day (¹H × 3); group 3, three fractionated doses of 17 cGy ¹H every other day followed by a single low dose of 15 cGy ⁵⁶Fe two days after the final ¹H dose (¹H × 3 + ⁵⁶Fe); and group 4, a single low dose of 15 cGy ⁵⁶Fe followed (after 2 days) by three fractionated doses of 17 cGy ¹H every other day (⁵⁶Fe + ¹H × 3). A subgroup of mice from each group underwent myocardial infarction (MI) surgery at 28 days postirradiation. Cardiac structure and function were assessed in all animals at days 7, 14 and 28 after MI surgery was performed. Compared to the control animals, the treatments that groups 2 and 3 received did not induce negative effects on cardiac function or structure. However, compared to all other groups, the animals in group 4, showed depressed left ventricular (LV) functions at 1 month with concomitant enhancement in cardiac fibrosis and induction of cardiac hypertrophy signaling at 3 months. In the irradiated and MI surgery groups compared to the control group, the treatments received by groups 2 and 4 did not induce negative effects at 1 month postirradiation and MI surgery. However, in group 3 after MI surgery, there was a 24% increase in mortality, significant decreases in LV function and a 35% increase in post-infarction size. These changes were associated with significant decreases in the angiogenic and cell survival signaling pathways. These data suggest that fractionated doses of radiation induces cellular and molecular changes that result in depressed heart functions both under basal conditions and particularly after myocardial infarction.

Nrf2 as a key player of redox regulation in cardiovascular diseases

The oxidative stress plays an important role in the development of cardiovascular diseases (CVD). In CVD progression an aberrant redox regulation was observed. In this regulation levels of reactive oxygen species (ROS) play an important role in cellular signaling, where Nrf2 is the key regulator of redox homeostasis. Keap1-Nrf2-ARE system regulates a great set of detoxificant and antioxidant enzymes in cells after ROS and electrophiles exposure. In this review we focus on radical-generating systems in cardiovascular system as well as on Nrf2 as a target against oxidative stress and a key player of redox regulation in cardiovascular diseases. We also summarize the current knowledge about the role of Nrf2 in pathophysiology of several CVD (hypertension, cardiac hypertrophy, cardiomyopathies) as well as in cardioprotection against myocardial ischemia/ reperfusion injury.

125I Seeds Radiation Induces Paraptosis-Like Cell Death via PI3K/AKT Signaling Pathway in HCT116 Cells

¹²⁵I seeds brachytherapy implantation has been extensively performed in unresectable and rerecurrent rectal carcinoma. Many studies on the cancer-killing activity of ¹²⁵I seeds radiation mainly focused on its ability to trigger apoptosis, which is the most well-known and dominant type of cell death induced by radiation. However our results showed some unique morphological features such as cell swelling, cytoplasmic vacuolation, and plasma membrane integrity, which is obviously different to apoptosis. In this study, clonogenic proliferation was carried out to assay survival fraction. Transmission electron microscopy was used to analyze ultrastructural and evaluate morphologic feature of HCT116 cells after exposure to ¹²⁵I seeds radiation. Immunofluorescence analysis was used to detect the origin of cytoplasmic vacuoles. Flow cytometry analysis was employed to detect the size and granularity of HCT116 cells. Western blot was performed to measure the protein level of AIP1, caspase-3, AKT, p-Akt (Thr308), p-Akt (Ser473), and β-actin. We found that ¹²⁵I seeds radiation activated PI3K/AKT signaling pathway and could trigger paraptosis-like cell death. Moreover, inhibitor of PI3K/AKT signaling pathway could inhibit paraptosis-like cell death induced by ¹²⁵I seeds radiation. Our data suggest that ¹²⁵I seeds radiation can induce paraptosis-like cell death via PI3K/AKT signaling pathway.