Renal and intraglomerular haemodynamics in chronic heart failure with preserved and reduced ejection fraction

Diagnostic potential of energy metabolism-related genes in heart failure with preserved ejection fraction

Background

Heart failure with preserved ejection fraction (HFpEF) is associated with changes in cardiac metabolism that affect energy supply in the heart. However, there is limited research on energy metabolism-related genes (EMRGs) in HFpEF.

Methods

The HFpEF mouse dataset (GSE180065, containing heart tissues from 10 HFpEF and five control samples) was sourced from the Gene Expression Omnibus database. Gene expression profiles in HFpEF and control groups were compared to identify differentially expressed EMRGs (DE-EMRGs), and the diagnostic biomarkers with diagnostic value were screened using machine learning algorithms. Meanwhile, we constructed a biomarker-based nomogram model for its predictive power, and functionality of diagnostic biomarkers were conducted using single-gene gene set enrichment analysis, drug prediction, and regulatory network analysis. Additionally, consensus clustering analysis based on the expression of diagnostic biomarkers was utilized to identify differential HFpEF-related genes (HFpEF-RGs). Immune microenvironment analysis in HFpEF and subtypes were performed for analyzing correlations between immune cells and diagnostic biomarkers as well as HFpEF-RGs. Finally, qRT-PCR analysis on the HFpEF mouse model was used to validate the expression levels of diagnostic biomarkers.

Results

We selected 5 biomarkers (Chrna2, Gnb3, Gng7, Ddit4l, and Prss55) that showed excellent diagnostic performance. The nomogram model we constructed demonstrated high predictive power. Single-gene gene set enrichment analysis revealed enrichment in aerobic respiration and energy derivation. Further, various miRNAs and TFs were predicted by Gng7, such as Gng7-mmu-miR-6921-5p, ETS1-Gng7. A lot of potential therapeutic targets were predicted as well. Consensus clustering identified two distinct subtypes of HFpEF. Functional enrichment analysis highlighted the involvement of DEGs-cluster in protein amino acid modification and so on. Additionally, we identified five HFpEF-RGs (Kcnt1, Acot1, Kcnc4, Scn3a, and Gpam). Immune analysis revealed correlations between Macrophage M2, T cell CD4+ Th1 and diagnostic biomarkers, as well as an association between Macrophage and HFpEF-RGs. We further validated the expression trends of the selected biomarkers through experimental validation.

Conclusion

Our study identified 5 diagnostic biomarkers and provided insights into the prediction and treatment of HFpEF through drug predictions and network analysis. These findings contribute to a better understanding of HFpEF and may guide future research and therapy development.

Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench

Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.

Advances in extracardiac mechanisms for heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a syndrome with highly heterogeneous clinical symptoms, and its incidence has been increasing in recent years. Compared with heart failure with reduced ejection fraction (HFrEF), HFpEF has a worse prognosis. Traditional therapies targeting the internal mechanisms of the heart show limited or inefficacy on HFpEF, and new therapeutic targets for HFpEF are expected to be found by focusing on the extracardiac mechanisms. Recent studies have shown that cardiopulmonary pathophysiological interaction exacerbates the progression of HFpEF. Hypertension, systemic vascular injury, and inflammatory response lead to coronary microvascular dysfunction, myocardial hypertrophy, and coronary microvascular remodeling. Acute kidney injury affects myocardial energy production, induces oxidative stress and catabolism of myocardial protein, which leads to myocardial dysfunction. Liver fibrosis mediates heart injury by abnormal protein deposition and inflammatory factors production. Skeletal muscle interacts with the sympathetic nervous system by metabolic signals. It also produces muscle factors, jointly affecting cardiac function. Metabolic syndrome, gut microbiota dysbiosis, immune system diseases, and iron deficiency promote the occurrence and development of HFpEF through metabolic changes, oxidative stress, and inflammatory responses. Therefore, the research on the extracardiac mechanisms of HFpEF has certain implications for model construction, mechanism research, and treatment strategy formulation.

Extracorporeal organ support and the kidney

The concept of extracorporeal organ support (ECOS) encompasses kidney, respiratory, cardiac and hepatic support. In an era of increasing incidence and survival of patients with single or multiple organ failure, knowledge on both multiorgan crosstalk and the physiopathological consequences of extracorporeal organ support have become increasingly important. Immerse within the cross-talk of multiple organ failure (MOF), Acute kidney injury (AKI) may be a part of the clinical presentation in patients undergoing ECOS, either as a concurrent clinical issue since the very start of ECOS or as a de novo event at any point in the clinical course. At any point during the clinical course of a patient with single or multiple organ failure undergoing ECOS, renal function may improve or deteriorate, as a result of the interaction of multiple factors, including multiorgan crosstalk and physiological consequences of ECOS. Common physiopathological ways in which ECOS may influence renal function includes: 1) multiorgan crosstalk (preexisting or de-novo 2)Hemodynamic changes and 3) ECOS-associated coagulation abnormalities and 3) Also, cytokine profile switch, neurohumoral changes and toxins clearance may contribute to the expected physiological changes related to ECOS. The main objective of this review is to summarize the described mechanisms influencing the renal function during the course of ECOS, including renal replacement therapy, extracorporeal membrane oxygenation/carbon dioxide removal and albumin dialysis.

Renal and intraglomerular haemodynamics in chronic heart failure with preserved and reduced ejection fraction

AIMS

Congestive heart failure (CHF) and impaired renal function are two often co-existing medical conditions and associated with adverse cardiovascular outcome. The aim of the current study was to assess renal and intraglomerular haemodynamics by constant infusion input clearance technique in subjects with CHF.

METHODS AND RESULTS

The group of subjects with CHF consisted of 27 individuals with HFpEF and 27 individuals with HFrEF and were compared with 31 healthy controls. Subjects underwent renal clearance examination to measure glomerular filtration rate (GFR) and renal blood and plasma flow (RBF and RPF) and to calculate intraglomerular haemodynamics such as resistances of the afferent (RA ) and efferent arterioles (RE ) as well as intraglomerular pressure (Pglom ). Measured GFR was lower in CHF subjects (68.1 ± 10.1 mL/min/1.73 m2 ) compared with controls (83.6 ± 13.4 mL/min/1.73 m2 , Padj  < 0.001) as was Pglom (Padj  < 0.001). Total renal vascular resistance (RVR) was higher in CHF subjects (87.3 ± 20.1 vs. 73.8 ± 17.1 dyn × s/cm5 , Padj  < 0.001) mediated by an increased resistance at the afferent site (3201 ± 1084 vs. 2181 ± 796 dyn × s/cm5 , Padj  < 0.001). Comparing HFpEF and HFrEF subjects, RA was higher in HFrEF subjects. The severity of CHF assessed by NT-proBNP revealed an inverse association with renal perfusion (RPF r = -0.421, P = 0.002, RBF r = -0.414, P = 0.002) and a positive relation with RVR (r = 0.346, P = 0.012) at the post-glomerular site (RE : r = 0.318, P = 0.022).

CONCLUSIONS

Renal function assessed by measured GFR is reduced and renal vascular resistance at the preglomerular, afferent site is increased in HFpEF and, to greater extent, in HFrEF. Our data indicate a close cardiorenal interaction in CHF.