A rat model of metabolic syndrome-related heart failure with preserved ejection fraction phenotype: pathological alterations and possible molecular mechanisms

Growth Differentiation Factor 15 Inhibits Cardiac Fibrosis, Oxidative Stress, Inflammation, and Apoptosis in a Rat Model of Heart Failure with Preserved Ejection Fraction

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a systemic syndrome primarily associated with fibrosis, oxidative stress, inflammation, and cellular apoptosis. Growth differentiation factor 15 (GDF15), a biomarker commonly used in clinical studies, exhibits protective effects on the myocardium. Therefore, the focus of the present study is to determine the mechanism by which GDF15 protects cardiac function in HFpEF.

METHODS

We conducted functional enrichment analysis and protein-protein interaction network analysis on genes highly expressed in HFpEF but lowly expressed in normal samples. We established an HFpEF rat model by feeding the rats with a high-fat diet and administering N-omega-nitro-l-arginine-methyl ester (L-NAME) in their drinking water and silenced GDF15 by tail vein injection of lentivirus (L3110). After 12 weeks of feeding, echocardiographic examinations were performed. Following euthanasia of the rats, blood and heart tissue samples were collected. Heart tissue sections were stained using Masson's trichrome and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining methods. Western blot (WB) analysis was employed to determine the concentrations of relevant proteins.

RESULTS

The echocardiographic results showed that compared with the HFpEF + MOCK group, the HFpEF+silencing GDF15 (siGDF15) group exhibited more severe cardiac dysfunction, with significant decreases in ejection fraction (p < 0.05) and E/A ratio (p < 0.001). WB results demonstrated that, compared with the HFpEF + MOCK group, the HFpEF+siGDF15 group exhibited increased expression of cardiac fibrosis-associated proteins, including collagen I (p < 0.01), collagen III (p < 0.01), and α-smooth muscle actin (α-SMA) (p < 0.01). Additionally, oxidative stress-associated biomarkers such as myeloperoxidase (MPO) (p < 0.01) and oxidized low-density lipoprotein (ox-LDL) (p < 0.01), inflammation-associated biomarkers, including interleukin-1 beta (IL-1β) (p < 0.01), interleukin-6 (IL-6) (p < 0.01), interleukin-8 (IL-8) (p < 0.01), and tumor necrosis factor α (TNFα) (p < 0.01), and apoptosis-associated biomarkers like cleaved caspase-3 (p < 0.01) and BCL2-associated X (BAX) (p < 0.01) were also upregulated in HFpEF+siGDF15 group.

CONCLUSIONS

Our research indicates that GDF15 preserves cardiac function by inhibiting myocardial fibrosis, reducing myocardial cell oxidative stress, alleviating cardiac inflammation, and suppressing myocardial cell apoptosis.

Glycogen synthase kinase-3β: A multifaceted player in ischemia-reperfusion injury and its therapeutic prospects

Ischemia-reperfusion injury (IRI) results in irreversible metabolic dysfunction and structural damage to tissues or organs, posing a formidable challenge in the field of organ implantation, cardiothoracic surgery, and general surgery. Glycogen synthase kinase-3β (GSK-3β) a multifunctional serine/threonine kinase, is involved in a variety of biological processes, including cell proliferation, apoptosis, and immune response. Phosphorylation of its tyrosine 216 and serine 9 sites positively and negatively regulates the activation and inactivation of the enzyme. Significantly, inhibition or inactivation of GSK-3β provides protection against IRI, making it a viable target for drug development. Though numerous GSK-3β inhibitors have been identified to date, the development of therapeutic treatments remains a considerable distance away. In light of this, this review summarizes the complicated network of GSK-3β roles in IRI. First, we provide an overview of GSK-3β's basic background. Subsequently, we briefly review the pathological mechanisms of GSK-3β in accelerating IRI, and highlight the latest progress of GSK-3β in multiorgan IRI, encompassing heart, brain, kidney, liver, and intestine. Finally, we discuss the current development of GSK-3β inhibitors in various organ IRI, offering a thorough and insightful reference for GSK-3β as a potential target for future IRI therapy.

FRBM Mini REVIEW: Chemogenetic approaches to probe redox dysregulation in heart failure

Chemogenetics refers to experimental methods that use novel recombinant proteins that can be dynamically and uniquely regulated by specific biochemicals. Chemogenetic approaches allow the precise manipulation of cellular signaling to delineate the molecular pathways involved in both physiological and pathological disease states. Approaches utilizing yeast d-amino acid oxidase (DAAO) enable manipulation of intracellular redox metabolism through generation of hydrogen peroxide in the presence of d-amino acids and have led to the development of new and informative animal models to characterize the impact of oxidative stress in heart failure and neurodegeneration. These chemogenetic models, in which DAAO expression is regulated by different tissue-specific promoters, have led to a range of cardiac phenotypes. This review discusses chemogenetic approaches to manipulate oxidative stress in models of heart failure. These approaches provide new insights into the relationships between redox metabolism and normal and pathologic states in the heart, as well as in other diseases characterized by oxidative stress.

Gastric GDF15 levels are regulated by age, sex, and nutritional status in rodents and humans

AIM

Growth differentiation factor 15 (GDF15) is a stress response cytokine that has been proposed as a relevant metabolic hormone. Descriptive studies have shown that plasma GDF15 levels are regulated by short term changes in nutritional status, such as fasting, or in obesity. However, few data exist regarding how GDF15 levels are regulated in peripheral tissues. The aim of the present work was to study the variations on gastric levels of GDF15 and its precursor under different physiological conditions, such as short-term changes in nutritional status or overfeeding achieved by HFD. Moreover, we also address the sex- and age-dependent alterations in GDF15 physiology.

METHODS

The levels of gastric and plasma GDF15 and its precursor were measured in lean and obese mice, rats and humans by western blot, RT-PCR, ELISA, immunohistochemistry and by an in vitro organ culture system.

RESULTS

Our results show a robust regulation of gastric GDF15 production by fasting in rodents. In obesity an increase in GDF15 secretion from the stomach is reflected with an increase in circulating levels of GDF15 in rats and humans. Moreover, gastric GDF15 levels increase with age in both rats and humans. Finally, gastric GDF15 levels display sexual dimorphism, which could explain the difference in circulating GFD15 levels between males and females, observed in both humans and rodents.

CONCLUSIONS

Our results provide clear evidence that gastric GDF15 is a critical contributor of circulating GDF15 levels and can explain some of the metabolic effects induced by GDF15.