Sodium butyrate ameliorates deoxycorticosterone acetate/salt-induced hypertension and renal damage by inhibiting the MR/SGK1 pathway

ELABELA/APJ Axis Prevents Diabetic Glomerular Endothelial Injury by Regulating AMPK/NLRP3 Pathway

ELABELA (ELA), a recently discovered peptide, is highly expressed in adult kidneys and the endothelium system. It has been identified as a novel endogenous ligand for the apelin receptor (APJ). This study aims to investigate the role of ELA in diabetic glomerular endothelial pyroptosis and its underlying mechanism. Initially, a significant decrease in ELA mRNA levels was observed in the renal cortex of db/db mice and high glucose-treated glomerular endothelial cells (GECs). It was also found that ELA deficiency in ELA+/- mice significantly accelerated diabetic glomerular injury, as shown by exacerbated glomerular morphological damage, increased serum creatine and blood urea nitrogen, and elevated 24-h urinary albumin excretion. In addition, in vivo overexpression of ELA prevented diabetic glomerular injury, reduced von Willebrand factor expression, restored endothelial marker CD31 expression, and attenuated the production of adhesive molecules such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Furthermore, in vitro studies confirmed that treatment with ELA inhibited GEC injury by regulating the NOD-like receptor protein 3 (NLRP3) inflammasome, as indicated by blocking NLRP3 inflammasome formation, decreasing cleaved Caspase-1 production, and inhibiting interleukin-1β and interleukin-18 production. Moreover, in vitro experiments demonstrated that the protective effects of ELA in GECs during hyperglycemia were diminished by inhibiting adenosine monophosphate-activated protein kinase (AMPK) using Compound C or by APJ deficiency. Taken together, this study provides the first evidence that ELA treatment could prevent diabetic glomerular endothelial injury, which is partly mediated by the regulation of the AMPK/NLRP3 signaling pathway. Therefore, pharmacologically targeting ELA may serve as a novel therapeutic strategy for diabetic kidney disease.

Butyrate alleviates renal fibrosis in CKD by regulating NLRP3-mediated pyroptosis via the STING/NF-κB/p65 pathway

Chronic kidney disease (CKD) is a serious and irreversible disease primarily characterized by chronic inflammation and renal fibrosis. Recent studies have suggested that gut microbiota-related metabolites, particularly short-chain fatty acids (SCFAs) are significantly associated with kidney diseases. Notably, butyrate, a type of SCFAs, plays a crucial role in this correlation. However, the effect of butyrate on renal fibrosis in patients with CKD and its potential mechanisms remain unclear. In this study, we demonstrated that butyrate levels are reduced as CKD progresses using a CKD C57BL/6 mouse model established by a 0.2% adenine diet. Exogenous supplementation of butyrate effectively alleviated renal fibrosis and repressed the levels of proteins associated with NLRP3-mediated pyroptosis (NLRP3, IL-1β, caspase-1, and GSDMD). Additionally, we conducted an in vitro experiment using HK-2 cells, which also confirmed that the elevated levels of NLRP3-mediated pyroptosis proteins in TGF-β1-stimulated HK-2 cells are reversed by butyrate intervention. Further, butyrate mitigated the activity of the STING/NF-κB/p65 pathway, and STING overexpression impaired the protective function of butyrate in CKD. Hence, we suggest that butyrate may have a renoprotective role in CKD, alleviating renal fibrosis possibly by regulating NLRP3-mediated pyroptosis via the STING/NF-κB/p65 pathway.

Bioactive lipids in hypertension

Hypertension is a major healthcare issue that afflicts one in every three adults worldwide and contributes to cardiovascular diseases, morbidity and mortality. Bioactive lipids contribute importantly to blood pressure regulation via actions on the vasculature, kidney, and inflammation. Vascular actions of bioactive lipids include blood pressure lowering vasodilation and blood pressure elevating vasoconstriction. Increased renin release by bioactive lipids in the kidney is pro-hypertensive whereas anti-hypertensive bioactive lipid actions result in increased sodium excretion. Bioactive lipids have pro-inflammatory and anti-inflammatory actions that increase or decrease reactive oxygen species and impact vascular and kidney function in hypertension. Human studies provide evidence that fatty acid metabolism and bioactive lipids contribute to sodium and blood pressure regulation in hypertension. Genetic changes identified in humans that impact arachidonic acid metabolism have been associated with hypertension. Arachidonic acid cyclooxygenase, lipoxygenase and cytochrome P450 metabolites have pro-hypertensive and anti-hypertensive actions. Omega-3 fish oil fatty acids eicosapentaenoic acid and docosahexaenoic acid are known to be anti-hypertensive and cardiovascular protective. Lastly, emerging fatty acid research areas include blood pressure regulation by isolevuglandins, nitrated fatty acids, and short chain fatty acids. Taken together, bioactive lipids are key contributors to blood pressure regulation and hypertension and their manipulation could decrease cardiovascular disease and associated morbidity and mortality.

The role and mechanism of butyrate in the prevention and treatment of diabetic kidney disease

Diabetic kidney disease (DKD) remains the leading cause of the end-stage renal disease and is a major burden on the healthcare system. The current understanding of the mechanisms responsible for the progression of DKD recognizes the involvement of oxidative stress, low-grade inflammation, and fibrosis. Several circulating metabolites that are the end products of the fermentation process, released by the gut microbiota, are known to be associated with systemic immune-inflammatory responses and kidney injury. This phenomenon has been recognized as the “gut–kidney axis.” Butyrate is produced predominantly by gut microbiota fermentation of dietary fiber and undigested carbohydrates. In addition to its important role as a fuel for colonic epithelial cells, butyrate has been demonstrated to ameliorate obesity, diabetes, and kidney diseases via G-protein coupled receptors (GPCRs). It also acts as an epigenetic regulator by inhibiting histone deacetylase (HDAC), up-regulation of miRNAs, or induction of the histone butyrylation and autophagy processes. This review aims to outline the existing literature on the treatment of DKD by butyrate in animal models and cell culture experiments, and to explore the protective effects of butyrate on DKD and the underlying molecular mechanism.

Moderation of gut microbiota and bile acid metabolism by chlorogenic acid improves high-fructose-induced salt-sensitive hypertension in mice

Chlorogenic acid (CGA) is a natural compound with many important pharmacological effects including anti-hypertension. This study aimed to investigate the anti-hypertensive effect of CGA on high-fructose-induced salt-sensitive hypertension and the underlying mechanism. Hypertension was induced in male C57BL/6 mice by 20% fructose in drinking water plus 4% sodium chloride in the diet (HFS) for 8 weeks. CGA (50, 100 or 200 mg kg^-1 d^-1) was orally administered to HFS-treated mice. The blood pressure of mice was recorded via the tail cuff method. The structure of gut microbiota and profiles of bile acids (BAs) in the serum were determined. Here, we found that HFS-elevated systolic blood pressure was greatly attenuated by CGA. The microbiota analysis showed that CGA restructured the HFS-treated gut microbiota, and markedly enriched Klebsiella. Oral administration of a Klebsiella isolate, Klebsiella oxytoca, also exhibited an anti-hypertensive effect in HFS-fed mice. Furthermore, we found that CGA and CGA-enriched K. oxytoca enhanced the expression of colonic Farnesoid X Receptor (FXR), modulated BA metabolism and enriched some BAs including deoxycholic acid (DCA) in the serum of HFS-fed mice. Treatment with DCA improved phenylephrine-induced vasoconstriction in arterioles of mice and attenuated hypertension in HFS-fed mice, suggesting that DCA serves as a link between gut microbiota and blood pressure. Our results clearly demonstrate that CGA attenuates HFS-induced hypertension in mice by modulating gut microbiota and BA metabolism. These findings provide insights into the potential mechanism of CGA for the treatment of hypertension.

Update on Immune Mechanisms in Hypertension

The contribution of immune cells in the initiation and maintenance of hypertension is undeniable. Several studies have established the association between hypertension, inflammation, and immune cells from the innate and adaptive immune systems. Here, we provide an update to our 2017 American Journal of Hypertension review on the overview of the cellular immune responses involved in hypertension. Further, we discuss the activation of immune cells and their contribution to the pathogenesis of hypertension in different in vivo models. We also highlight existing gaps in the field of hypertension that need attention. The main goal of this review is to provide a knowledge base for translational research to develop therapeutic strategies that can improve cardiovascular health in humans.

Role of the microbiota in hypertension and antihypertensive drug metabolism

Recent evidence suggests that the gut microbiota plays an important role in the development and pathogenesis of hypertension. Dysbiosis, an imbalance in the composition and function of the gut microbiota, was shown to be associated with hypertension in both animal models and humans. In this review, we provide insights into host-microbiota interactions and summarize the evidence supporting the importance of the microbiota in blood pressure (BP) regulation. Metabolites produced by the gut microbiota, especially short-chain fatty acids (SCFAs), modulate BP and vascular responses. Harmful gut-derived metabolites, such as trimethylamine N-oxide and several uremic toxins, exert proatherosclerotic, prothrombotic, and proinflammatory effects. High-salt intake alters the composition of the microbiota, and this microbial alteration contributes to the pathogenesis of salt-sensitive hypertension. In addition, the microbiota may impact the metabolism of drugs and steroid hormones in the host. The drug-metabolizing activities of the microbiota affect the pharmacokinetic parameters of antihypertensive drugs and contribute to the pathogenesis of licorice-induced pseudohyperaldosteronism. Furthermore, the oral microbiota plays a role in BP regulation by producing nitric oxide, which lowers BP via its vasodilatory effects. Thus, antihypertensive intervention strategies targeting the microbiota, such as the use of prebiotics, probiotics, and postbiotics (e.g., SCFAs), are considered new therapeutic options for the treatment of hypertension.

EVI1 activates tumor-promoting transcriptional enhancers in pancreatic cancer

Cancer cells utilize epigenetic alterations to acquire autonomous capabilities for tumor maintenance. Here, we show that pancreatic ductal adenocarcinoma (PDA) cells utilize super-enhancers (SEs) to activate the transcription factor EVI1 (ecotropic viral integration site 1) gene, resulting in activation of an EVI1-dependent transcription program conferring PDA tumorigenesis. Our data indicate that SE is the vital cis-acting element to maintain aberrant EVI1 transcription in PDA cells. Consistent with disease progression and inferior survival outcomes of PDA patients, we further show that EVI1 upregulation is a major cause of aggressive tumor phenotypes. Specifically, EVI1 promotes anchorage-independent growth and motility in vitro and enhances tumor propagation in vivo. Mechanistically, EVI1-dependent activation of tumor-promoting gene expression programs through the stepwise configuration of the active enhancer chromatin attributes to these phenotypes. In sum, our findings support the premise that EVI1 is a crucial driver of oncogenic transcription programs in PDA cells. Further, we emphasize the instructive role of epigenetic aberrancy in establishing PDA tumorigenesis.