Diabetic cardiomyopathy - Zinc preventive and therapeutic potentials by its anti-oxidative stress and sensitizing insulin signaling pathways

Zinc promotes microbial p-coumaric acid production that protects against cholestatic liver injury

Cholestatic liver disease (CLD) is a common liver disorder with limited treatment options. Here, we demonstrate that zinc (Zn) supplementation can alter the gut microbiome to mitigate cholestatic liver injury. Oral Zn altered the microbiota of mice and humans (this study was registered at clinicaltrials.gov [NCT05597137]), increasing the abundance of Blautia producta (B. producta) and promoting the generation of p-coumaric acid. Additionally, p-coumaric acid concentrations were negatively correlated with liver injury parameters in CLD patients. In mice, the protective effects of Zn were partially mediated by p-coumaric acid, which directly bound to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and suppressed the production of reactive oxygen species (ROS) in hepatocytes, thus preventing hepatocyte cell death and liver damage. Additionally, knocking out the histidine ammonia-lyase, which catalyzes the conversion of tyrosine to p-coumaric acid in B. producta, blunted the protective effects of Zn. These findings highlight a host-microbiota interaction that is stimulated by Zn supplementation, providing potential benefits for CLD.

J-shaped association between serum glucose potassium ratio and prognosis in heart failure with preserved ejection fraction with stronger predictive value in non-diabetic patients

BACKGROUND

The relationship between serum glucose/potassium ratio (GPR) and the adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF) has not been completely clarified.

METHODS

Patients were included from the American cohort of the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial. The primary endpoint was the composite of cardiovascular mortality, aborted cardiac arrest, and hospitalization for HF. The Cox regression models were applied to calculate the hazard ratio (HR) and 95% confidence interval (CI) to examine the relationship between GPR and prognosis. Restricted cubic spline (RCS) curves were performed to explore the nonlinear relationship between GPR and the primary endpoint. Receiver Operating Characteristic (ROC) curves were constructed, and the areas under the curves (AUCs) for GPR and its components were compared using the DeLong test. Subgroup analysis and interaction effect were also explored.

RESULTS

A total of 1749 HFpEF patients were included. During the follow-up, 514 (29.4%) patients reached the primary outcome. An increase in GPR was independently associated with a higher risk in the primary endpoint [Tertile 3 vs. Tertile 1: HR (95% CI), 1.35 (1.07-1.70), P = 0.012] and HF hospitalization [Tertile 3 vs. Tertile 1: HR (95% CI), 1.57 (1.20-2.05), P = 0.001]. RCS curve showed a J-shape trend between GPR and primary endpoint (non-linear P = 0.002). The AUC for GPR was superior to that of the glucose and potassium (De long test P < 0.05). Additionally, the prognostic value of GPR was stronger in patients without diabetes and with less severe heart failure symptoms (P interaction < 0.05).

CONCLUSION

A J-shaped relationship was existed between GPR levels and the primary outcome in HFpEF patients. An increased GPR was an independent predictor of poor prognosis in HFpEF patients, especially in non-diabetic patients and those with less severe heart failure symptoms.

The signaling pathways of selected traditional Chinese medicine prescriptions and their metabolites in the treatment of diabetic cardiomyopathy: a review

Diabetic cardiomyopathy (DCM) is a myocardial-specific microvascular disease caused by diabetes that affects the structure and function of the heart and is considered to be the leading cause of morbidity and death in patients with diabetes. Currently, there is no specific treatment or preventive drug for DCM, and there is an urgent need to develop new drugs to treat DCM. Traditional Chinese medicine (TCM) has rich experience in the treatment of DCM, and its characteristics of multi-target, multi-pathway, multi-component, and few side effects can effectively deal with the complexity and long-term nature of DCM. Growing evidence suggests that myocardial fibrosis, inflammation, oxidative stress, apoptosis, cardiac hypertrophy, and advanced glycation end product deposition were the main pathologic mechanisms of DCM. According to the pathological mechanism of DCM, this study revealed the potential of metabolites and prescriptions in TCM against DCM from the perspective of signaling pathways. The results showed that TGF-β/Smad, NF-κB, PI3K/AKT, Nrf2, AMPK, NLRP3, and Wnt/β-catenin signaling pathways were the key signaling pathways for TCM treatment of DCM. The aim of this study was to summarize and update the signaling pathways for TCM treatment of DCM, to screen potential targets for drug candidates against DCM, and to provide new ideas and more experimental evidence for the clinical use of TCM treatment of DCM.

Fe-Zn alloy, a new biodegradable material capable of reducing ROS and inhibiting oxidative stress

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable biocompatibility. Currently, research on Fe-based materials mainly focuses on regulating the degradation rate. However, excessive release of Fe ions during material degradation will induce the generation of reactive oxygen species (ROS), leading to oxidative stress and ferroptosis. Therefore, the control of ROS release and the improvement of biocompatibility for Fe-based materials are very important. In this study, new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy degradation. Initially, the impact of three potential degradation ions (Fe2+, Fe3+, Zn2+) from the Fe-Zn alloy on human endothelial cell (EC) activity and migration ability was investigated. Subsequently, cell adhesion, cell activity, ROS production and DNA damage were assessed at various locations surrounding the alloy. Finally, the influence of different concentrations of Zn2+ in the medium on cell viability and ROS production was evaluated. High levels of ROS exhibited evident toxic effects on ECs and promoted DNA damage. As an antioxidant, Zn2+ effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/l. These findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation thereby enhancing cytocompatibility.

Beneficial impact of cardiac heavy metal scavenger metallothionein in sepsis-provoked cardiac anomalies dependent upon regulation of endoplasmic reticulum stress and ferroptosis but not autophagy

AIMS

Sepsis represents a profound proinflammatory response with a major contribution from oxidative injury. Here we evaluated possible impact of heavy metal scavenger metallothionein (MT) on endotoxin lipopolysaccharide (LPS)-induced oxidative stress, endoplasmic reticulum (ER) stress, autophagy, and ferroptosis enroute to myocardial injury along with interplay among these stress domains.

MATERIALS AND METHODS

Echocardiographic, cardiomyocyte mechanical and intracellular Ca2+ responses were monitored in myocardia from WT and transgenic mice with cardiac-selective MT overexpression challenged with LPS. Oxidative stress, stress signaling (p38, ERK, JNK), ER stress, autophagy, and ferroptosis were scrutinized.

KEY FINDINGS

RNAseq analysis revealed discrepant patterns in ferroptosis between LPS-exposed and normal murine hearts. LPS insult enlarged LV end systolic dimension, suppressed fractional shortening, ejection fraction, maximal velocity of shortening/relengthening and peak shortening, as well as elongated relengthening along with dampened intracellular Ca2+ release and reuptake. In addition, LPS triggered oxidative stress (lowered glutathione/glutathione disulfide ratio and O2- production), activation of stress cascades (p38, ERK, JNK), ER stress (GRP78, PERK, Gadd153, and IRE1α), inflammation (TNFα and iNOS), unchecked autophagy (LCB3, Beclin-1 and Atg7), ferroptosis (GPx4 and SLC7A11) and interstitial fibrosis. Although MT overexpression itself did not reveal response on cardiac function, it attenuated or mitigated LPS-evoked alterations in echocardiographic, cardiomyocyte contractile and intracellular Ca2+ characteristics, O2- production, TNFα level, ER stress and ferroptosis (without affecting autophagy, elevated AMP/ATP ratio, and iNOS). In vitro evidence revealed beneficial effects of suppression of oxidative stress, ER stress and ferroptosis against LPS-elicited myocardial anomalies.

SIGNIFICANCE

These data strongly support the therapeutic promises of MT and ferroptosis in septic cardiomyopathy.

Potential therapeutic targets for the prevention of diabetic nephropathy: Glycyrrhetinic acid

Uncontrolled hyperglycemia or poorly managed disease increases the propensity for a number of diabetes-related complications targeting major organs including the heart, eyes, and kidney. Although the mechanisms by which diabetes induces cardiovascular diseases include oxidative stress and inflammation, when insulin resistance remains the key to the pathogenesis, as implicated in the two reviews in this issue. This editorial mainly comments on the potential preventive application of glycyrrhetinic acid (or 18β-GA) in relation to diabetic nephropathy. The thera-peutic or preventive effects of 18β-GA, as a hydrolytic product of glycyrrhizic acid that is a component of licorice, have been appreciated in other disorders, but have received much less attention in relation to diabetic complications. A study in this issue has identified 18β-GA as a therapeutic for preventing diabetic nephropathy and provides evidence to support efficacy in cultured human renal tubule cells in vitro. Although it represents a pilot study, the observations support a new therapeutic approach that warrants further ex-ploration.