Elevated circulating growth differentiation factor 15 is related to decreased heart rate variability in chronic kidney disease patients

Comprehensive viewpoints on heart rate variability at high altitude

OBJECTIVES

Hypoxia is a physiological state characterized by reduced oxygen levels in organs and tissues. It is a common clinicopathological process and a major cause of health problems in highland areas.  Heart rate variability (HRV) is a measure of the balance in autonomic innervation to the heart. It provides valuable information on the regulation of the cardiovascular system by neurohumoral factors, and changes in HRV reflect the complex interactions between multiple systems. In this review, we provide a comprehensive overview of the relationship between high-altitude hypoxia and HRV. We summarize the different mechanisms of diseases caused by hypoxia and explore the changes in HRV across various systems. Additionally, we discuss relevant pharmaceutical interventions. Overall, this review aims to provide research ideas and assistance for in-depth studies on HRV. By understanding the intricate relationship between high-altitude hypoxia and HRV, we can gain insights into the underlying mechanisms and potential therapeutic approaches to mitigate the effects of hypoxia on cardiovascular and other systems.

METHODS

The relevant literature was collected systematically from scientific database, including PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), Baidu Scholar, as well as other literature sources, such as classic books of hypoxia.

RESULTS

There is a close relationship between heart rate variability and high-altitude hypoxia. Heart rate variability is an indicator that evaluates the impact of hypoxia on the cardiovascular system and other related systems. By improving the observation of HRV, we can estimate the progress of cardiovascular diseases and predict the impact on other systems related to cardiovascular health. At the same time, changes in heart rate variability can be used to observe the efficacy of preventive drugs for altitude related diseases.

CONCLUSIONS

HRV can be used to assess autonomic nervous function under various systemic conditions, and can be used to predict and monitor diseases caused by hypoxia at high altitude. Investigating the correlation between high altitude hypoxia and heart rate variability can help make HRV more rapid, accurate, and effective for the diagnosis of plateau-related diseases.

GDF15 in Appetite and Exercise: Essential Player or Coincidental Bystander?

Growth differentiation factor 15 (GDF15) has recently moved to the forefront of metabolism research. When administered pharmacologically, GDF15 reduces food intake and lowers body weight via the hindbrain-situated receptor GFRAL (glial cell-derived neurotrophic factor family receptor alpha-like). Endogenous GDF15 is a ubiquitous cellular stress signal that can be produced and secreted by a variety of cell types. Circulating levels are elevated in a series of disease states, but also in response to exogenous agents such as metformin, colchicine, AICAR, and cisplatin. Recently, exercise has emerged as a relevant intervention to interrogate GDF15 physiology. Prolonged endurance exercise increases circulating GDF15 to levels otherwise associated with certain pathological states and in response to metformin treatment. The jury is still out on whether GDF15 is a functional "exerkine" mediating organ-to-brain crosstalk or whether it is a coincidental bystander. In this review, we discuss the putative physiological implication of exercise-induced GDF15, focusing on the potential impact on appetite and metabolism.

Association Between Circulating GDF-15 and Cardio-Renal Outcomes and Effect of Canagliflozin: Results From the CANVAS Trial

Background

Studies have suggested that sodium glucose co‐transporter 2 inhibitors exert anti‐inflammatory effects. We examined the association of baseline growth differentiation factor‐15 (GDF‐15), a marker of inflammation and cellular injury, with cardiovascular events, hospitalization for heart failure (HF), and kidney outcomes in patients with type 2 diabetes in the CANVAS (Canagliflozin Cardiovascular Assessment Study) and determined the effect of the sodium glucose co‐transporter 2 inhibitor canagliflozin on circulating GDF‐15.

Methods and Results

The CANVAS trial randomized 4330 people with type 2 diabetes at high cardiovascular risk to canagliflozin or placebo. The association between baseline GDF‐15 and cardiovascular (non‐fatal myocardial infarction, non‐fatal stroke, cardiovascular death), HF, and kidney (40% estimated glomerular filtration rate decline, end‐stage kidney disease, renal death) outcomes was assessed using multivariable adjusted Cox regression models. During median follow‐up of 6.1 years (N=3549 participants with available samples), 555 cardiovascular, 129 HF, and 137 kidney outcomes occurred. Each doubling in baseline GDF‐15 was significantly associated with a higher risk of cardiovascular (hazard ratio [HR], 1.2; 95% CI, 1.0‒1.3), HF (HR, 1.5; 95% CI, 1.2‒2.0) and kidney (HR, 1.5; 95% CI, 1.2‒2.0) outcomes. Baseline GDF‐15 did not modify canagliflozin’s effect on cardiovascular, HF, and kidney outcomes. Canaglifozin treatment modestly lowered GDF‐15 compared with placebo; however, GDF‐15 did not mediate the protective effect of canagliflozin on cardiovascular, HF, or kidney outcomes.

Conclusions

In patients with type 2 diabetes at high cardiovascular risk, higher GDF‐15 levels were associated with a higher risk of cardiovascular, HF, and kidney outcomes. Canagliflozin modestly lowered GDF‐15, but GDF‐15 reduction did not mediate the protective effect of canagliflozin.

Negative Regulators of Inflammation Response to the Dynamic Expression of Cytokines in DF-1 and MDCK Cells Infected by Avian Influenza Viruses

The H5N1 and H9N2 avian influenza viruses (AIVs) seriously endanger the poultry industry and threaten human health. Characteristic inflammatory responses caused by H5N1 and H9N2 AIVs in birds and mammals result in unique clinical manifestations. The role of anti-inflammatory regulators, PTX3, Del-1, and GDF-15, in H5N1 and H9N2-AIV-mediated inflammation in birds and mammals has not yet been verified. Here, the expression of PTX3, Del-1, and GDF-15 in DF-1 and MDCK cells infected with H5N1 and H9N2 AIVs and their effect on inflammatory cytokines were analyzed. Infection with both AIVs increased PTX3, Del-1, and GDF-15 expression in DF-1 and MDCK cells. Infection with H9N2 or H5N1 AIV in DF-1 and MDCK cells with overexpression of all three factors, either alone or in combination, inhibited the expression of tested inflammatory cytokines. Furthermore, co-expression of PTX3, Del-1, and GDF-15 enhanced the inhibition, irrespective of the cell line. The findings from this study offer insight into the pathogenic differences between H5N1 and H9N2 AIVs in varied hosts. Moreover, our findings can be used to help screen for host-specific anti-inflammatory agents.