Possible organ-protective effects of renal denervation: insights from basic studies

Renal Denervation as a Novel Therapeutic Approach for Resistant Hypertension: Mechanisms, Efficacy and Future Directions

Resistant hypertension is a state characterized by sustained hypertension despite adherence to the standard pharmacological treatment with beta-blockers, calcium channel blockers, diuretics, and ACE inhibitors or ARBs. Resistant hypertension is a problem now in cardiovascular medicine because of its association with increased stroke, heart failure, kidney disease, and vision loss. Renal denervation (RDN) is an invasive treatment strategy for patients with hypertension who are unresponsive to pharmacological therapy. Therefore, this procedure has become a feasible alternative, and this review explores and compares with other possible novel options. RDN's mechanisms, efficacy, safety, and future directions are also discussed. No serious side effects have been reported in the short-term use of RDN, but some of the complications include renal stenosis and hypertensive urgencies in the long term. Despite this, RDN can benefit patients who are non-compliant with medications or are intolerant. However, it should also be pointed out that some clinical studies have not given consistent results. RDN may be employed as secondary therapy as opposed to the primary line of treatment in resistant hypertension. Subsequent studies should assess the technique's durability and establish customized approaches to deliver RDN safely while determining specific biomarkers that can predict patients' outcomes.

Bioinformatics analysis of the expression of potential common genes and immune-related genes between atrial fibrillation and chronic kidney disease

Research objective

This study is based on bioinformatics analysis to explore the co-expressed differentially expressed genes (DEGs) between atrial fibrillation (AF) and chronic kidney disease (CKD), identify the biomarkers for the occurrence and development of the two diseases, investigate the potential connections between AF and CKD, and explore the associations with immune cells.

Methods

We downloaded Two AF gene chip datasets (GSE79768, GSE14975) and two CKD gene chip datasets (GSE37171, GSE120683) from the GEO database. After pre-processing and standardizing the datasets, two DEGs datasets were obtained. The DEGs were screened using R language, and the intersection was taken through Venn diagrams to obtain the co-expressed DEGs of AF and CKD. To obtain the signal pathways where the co-expressed DEGs were significantly enriched, GO/KEGG enrichment analyses were used to analysis the co-expressed DEGs. The Cytoscape software was used to further construct a PPI network and screen key characteristic genes, and the top 15 co-expressed DEGs were screened through the topological algorithm MCC. To further screen key characteristic genes, two machine-learning algorithms, LASSO regression and RF algorithm, were performed to screen key characteristic genes for the two disease datasets respectively to determine the diagnostic values of the characteristic genes in the two diseases. The GeneMANIA online database and Networkanalyst platform were used to construct gene-gene and TFs-gene interaction network diagrams respectively to predict gene functions and find key transcription factors. Finally, the correlation between key genes and immune cell subtypes was performed by Spearman analysis.

Research results

A total of 425 DEGs were screened out from the AF dataset, and 4,128 DEGs were screened out from the CKD dataset. After taking the intersection of the two, 82 co-expressed DEGs were obtained. The results of GO enrichment analysis of DEGs showed that the genes were mainly enriched in biological processes such as secretory granule lumen, blood microparticles, complement binding, and antigen binding. KEGG functional enrichment analysis indicated that the genes were mainly enriched in pathways such as the complement coagulation cascade, systemic lupus erythematosus, and Staphylococcus aureus infection. The top 15 DEGs were obtained through the MCC topological algorithm of Cytoscape software. Subsequently, based on LASSO regression and RF algorithm, the key characteristic genes of the 15 co-expressed DEGs of AF and CKD were further screened, and by taking the intersection through Venn diagrams, five key characteristic genes were finally obtained: PPBP, CXCL1, LRRK2, RGS18, RSAD2. ROC curves were constructed to calculate the area under the curve to verify the diagnostic efficacy of the key characteristic genes for diseases. The results showed that RSAD2 had the highest diagnostic value for AF, and the diagnostic values of PPBP, CXCL1, and RSAD2 for CKD were all at a relatively strong verification level. Based on AUC >0.7, co-expressed key genes with strong diagnostic efficacy were obtained: PPBP, CXCL1, RSAD2. The results of the GeneMANIA online database showed that the two biomarkers, BBPB and CXCL1, mainly had functional interactions with cytokine activity, chemokine receptor activity, cell response to chemokines, neutrophil migration, response to chemokines, granulocyte chemotaxis, and granulocyte migration. The TFs-gene regulatory network identified FOXC1, FOXL1, and GATA2 as the main transcription factors of the key characteristic genes. Finally, through immune infiltration analysis, the results indicated that there were various immune cell infiltrations in the development processes of AF and CKD.

Research conclusion

PPBP, CXCL1, and RSAD2 are key genes closely related to the occurrence and development processes between AF and CKD. Among them, the CXCLs/CXCR signaling pathway play a crucial role in the development processes of the two diseases likely. In addition, FOXC1, FOXL1, and GATA2 may be potential therapeutic targets for AF combined with CKD, and the development of the diseases is closely related to immune cell infiltration.

Chronic activation of β-adrenergic receptors leads to tissue water and electrolyte retention

β-Adrenergic receptors (β-ARs) are expressed on the membranes of various cell types, and their activation affects body water balance by modulating renal sodium and water excretion, cardiovascular function, and metabolic processes. However, β-AR-associated body fluid imbalance has not been well characterized. In the present study, we hypothesized that chronic β-AR stimulation increases electrolyte and water content at the tissue level. We evaluated the effects of isoproterenol, a nonselective β-AR agonist, on electrolyte and water balance at the tissue level. Continuous isoproterenol administration for 14 days induced cardiac hypertrophy, associated with sodium-driven water retention in the heart; increased the total body sodium, potassium, and water contents at the tissue level; and increased the water intake and blood pressure of mice. There was greater urine output in response to the isoproterenol-induced body water retention. These isoproterenol-induced changes were reduced by propranolol, a nonselective β receptor inhibitor. Isoproterenol-treated mice, even without excessive water intake, had higher total body electrolyte and water contents, and this tissue water retention was associated with lower dry body mass, suggesting that β-AR stimulation in the absence of excess water intake induces catabolism and water retention. These findings suggest that β-AR activation induces tissue sodium and potassium retention, leading to body fluid retention, with or without excess water intake. This characterization of β-AR-induced electrolyte and fluid abnormalities improves our understanding of the pharmacological effects of β-AR inhibitors. SIGNIFICANCE STATEMENT: This study has shown that chronic β-adrenergic receptor (β-AR) stimulation causes cardiac hypertrophy associated with sodium-driven water retention in the heart and increases the accumulation of body sodium, potassium, and water at the tissue level. This characterization of the β-AR-induced abnormalities in electrolyte and water balance at the tissue level improves our understanding of the roles of β-AR in physiology and pathophysiology and the pharmacological effects of β-AR inhibitors.

Effects of renal denervation on the course of cardiorenal syndrome: insight from studies with fawn-hooded hypertensive rats

Combination of chronic kidney disease (CKD) and heart failure (HF) results in extremely high morbidity and mortality. The current guideline-directed medical therapy is rarely effective and new therapeutic approaches are urgently needed. The study was designed to examine if renal denervation (RDN) will exhibit long-standing beneficial effects on the HF- and CKD-related morbidity and mortality. Fawn-hooded hypertensive rats (FHH) served as a genetic model of CKD and fawn-hooded low-pressure rats (FHL) without CKD served as controls. HF was induced by creation of aorto-caval fistula (ACF). RDN was performed 28 days after creation of ACF and the follow-up period was 70 days. ACF FHH subjected to sham-RDN had survival rate of 34 % i.e. significantly lower than 79 % observed in sham-denervated ACF FHL. RDN did not improve the condition and the final survival rate, both in ACF FHL and in ACF FHH. In FHH basal albuminuria was markedly higher than in FHL, and further increased throughout the study. RDN did not lower albuminuria and did not reduce renal glomerular damage in FHH. In these rats creation of ACF resulted in marked bilateral cardiac hypertrophy and alterations of cardiac connexin-43, however, RDN did not modify any of the cardiac parameters. Our present results further support the notion that kidney damage aggravates the HF-related morbidity and mortality. Moreover, it is clear that in the ACF FHH model of combined CKD and HF, RDN does not exhibit any important renoprotective or cardioprotective effects and does not reduce mortality. Key words Chronic kidney disease, Heart failure, Renal denervation, Fawn-hooded hypertensive rats.

Autonomic neuronal modulations in cardiac arrhythmias: Current concepts and emerging therapies

The pathophysiology of atrial fibrillation and ventricular tachycardia that result in cardiac arrhythmias is related to the sustained complicated mechanisms of the autonomic nervous system. Atrial fibrillation is when the heart beats irregularly, and ventricular arrhythmias are rapid and inconsistent heart rhythms, which involves many factors including the autonomic nervous system. It's a complex topic that requires careful exploration. Cultivation of speculative knowledge on atrial fibrillation; the irregular rhythm of the heart and ventricular arrhythmias; rapid oscillating waves resulting from mistakenly inconsistent P waves, and the inclusion of an autonomic nervous system is an inconceivable approach toward clinical intricacies. Autonomic modulation, therefore, acquires new expansions and conceptions of appealing therapeutic intelligence to prevent cardiac arrhythmia. Notably, autonomic modulation uses the neural tissue's flexibility to cause remodeling and, hence, provide therapeutic effects. In addition, autonomic modulation techniques included stimulation of the vagus nerve and tragus, renal denervation, cardiac sympathetic denervation, and baroreceptor activation treatment. Strong preclinical evidence and early human studies support the annihilation of cardiac arrhythmias by sympathetic and parasympathetic systems to transmigrate the cardiac myocytes and myocardium as efficient determinants at the cellular and physiological levels. However, the goal of this study is to draw attention to these promising early pre-clinical and clinical arrhythmia treatment options that use autonomic modulation as a therapeutic modality to conquer the troublesome process of irregular heart movements. Additionally, we provide a summary of the numerous techniques for measuring autonomic tone such as heart rate oscillations and its association with cutaneous sympathetic nerve activity appear to be substitute indicators and predictors of the outcome of treatment.