Role of macrophage PPARγ in experimental hypertension

Emerging Roles and Therapeutic Applications of Arachidonic Acid Pathways in Cardiometabolic Diseases

Cardiometabolic disease has become a major health burden worldwide, with sharply increasing prevalence but highly limited therapeutic interventions. Emerging evidence has revealed that arachidonic acid derivatives and pathway factors link metabolic disorders to cardiovascular risks and intimately participate in the progression and severity of cardiometabolic diseases. In this review, we systemically summarized and updated the biological functions of arachidonic acid pathways in cardiometabolic diseases, mainly focusing on heart failure, hypertension, atherosclerosis, nonalcoholic fatty liver disease, obesity, and diabetes. We further discussed the cellular and molecular mechanisms of arachidonic acid pathway-mediated regulation of cardiometabolic diseases and highlighted the emerging clinical advances to improve these pathological conditions by targeting arachidonic acid metabolites and pathway factors.

PPARγ Agonist Rosiglitazone and Antagonist GW9662: Antihypertensive Effects on Chronic Intermittent Hypoxia-Induced Hypertension in Rats

The increased incidence of hypertension associated with obstructive sleep apnea (OSA) presents significant physical, psychological, and economic challenges. Peroxisome proliferator-activated receptor gamma (PPARγ) plays a role in both OSA and hypertension, yet the therapeutic potential of PPARγ agonists and antagonists for OSA-related hypertension remains unexplored. Therefore, we constructed a chronic intermittent hypoxia (CIH)-induced hypertension rat model that mimics the pathogenesis of OSA-related hypertension in humans. The model involved administering PPARγ agonist rosiglitazone (RSG), PPARγ antagonist GW9662, or normal saline, followed by regular monitoring of blood pressure and thoracic aorta analysis using staining and electron microscopy. Intriguingly, our results indicated that both RSG and GW9662 appeared to potently counteract CIH-induced hypertension. In silico study suggested that GW9662's antihypertensive effect might mediated through angiotensin II receptor type 1 (AGTR1). Our findings provide insights into the mechanisms of OSA-related hypertension and propose novel therapeutic targets.

Effects of fermented Yupingfeng on intramuscular fatty acids and ruminal microbiota in Qingyuan black goats

Our previous work has demonstrated that Yupingfeng, a Chinese herb medicine, considered as prebiotic showed beneficial properties in poultry health and disease prevention and regulated intestinal microbiota. The effects of Yupingfeng on fatty acids related to meat flavor and ruminal microbiota are not yet known in Qingyuan black goat. In this study, we supplemented fermented (FYP) and unfermented (UYP) Yupingfeng in different combinations to 90 goats. Compared with the normal control group, FYP and UYP significantly increased the concentration of palmitic acid, octadecanoic acid, and arachidonate acid (related to meat flavor) in the longissimus dorsi muscle (p < .05). In addition, the significant upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid translocase (CD36) was observed in the FYP and UYP groups (p < .05). In addition, Firmicutes and Bacteroidetes were the most abundance in goat rumen. At the genus level, FYP and UYP significantly increased Ruminococcus related to fiber degradation, and Alistipes related to short-chain fatty acids production. In summary, Yupingfeng could improve fatty acids of goat meat, which is probably triggered by the increase of PPARγ and CD36, and microbial activity. Besides, FYP showed more beneficial effects than UYP, with increased flavor fatty acids and beneficial microbes.

Obesity, Hypertension, and Cardiac Dysfunction: Novel Roles of Immunometabolism in Macrophage Activation and Inflammation

Obesity and hypertension, which often coexist, are major risk factors for heart failure and are characterized by chronic, low-grade inflammation, which promotes adverse cardiac remodeling. While macrophages play a key role in cardiac remodeling, dysregulation of macrophage polarization between the proinflammatory M1 and anti-inflammatory M2 phenotypes promotes excessive inflammation and cardiac injury. Metabolic shifting between glycolysis and mitochondrial oxidative phosphorylation has been implicated in macrophage polarization. M1 macrophages primarily rely on glycolysis, whereas M2 macrophages rely on the tricarboxylic acid cycle and oxidative phosphorylation; thus, factors that affect macrophage metabolism may disrupt M1/M2 homeostasis and exacerbate inflammation. The mechanisms by which obesity and hypertension may synergistically induce macrophage metabolic dysfunction, particularly during cardiac remodeling, are not fully understood. We propose that obesity and hypertension induce M1 macrophage polarization via mechanisms that directly target macrophage metabolism, including changes in circulating glucose and fatty acid substrates, lipotoxicity, and tissue hypoxia. We discuss canonical and novel proinflammatory roles of macrophages during obesity-hypertension-induced cardiac injury, including diastolic dysfunction and impaired calcium handling. Finally, we discuss the current status of potential therapies to target macrophage metabolism during heart failure, including antidiabetic therapies, anti-inflammatory therapies, and novel immunometabolic agents.

Macrophages dictate the progression and manifestation of hypertensive heart disease

BACKGROUND

Inflammation has been implicated in the initiation, progression and manifestation of hypertensive heart disease. We sought to determine the role of monocytes/macrophages in hypertension and pressure overload induced left ventricular (LV) remodeling.

METHODS AND RESULTS

We used two models of LV hypertrophy (LVH). First, to induce hypertension and LVH, we fed Sabra salt-sensitive rats with a high-salt diet. The number of macrophages increased in the hypertensive hearts, peaking at 10 weeks after a high-salt diet. Surprisingly, macrophage depletion, by IV clodronate (CL) liposomes, inhibited the development of hypertension. Moreover, macrophage depletion reduced LVH by 17% (p<0.05), and reduced cardiac fibrosis by 75%, compared with controls (p=0.001). Second, to determine the role of macrophages in the development and progression of LVH, independent of high-salt diet, we depleted macrophages in mice subjected to transverse aortic constriction and pressure overload. Significantly, macrophage depletion, for 3 weeks, attenuated LVH: a 12% decrease in diastolic and 20% in systolic wall thickness (p<0.05), and a 13% in LV mass (p=0.04), compared with controls. Additionally, macrophage depletion reduced cardiac fibrosis by 80% (p=0.006). Finally, macrophage depletion down-regulated the expression of genes associated with cardiac remodeling and fibrosis: transforming growth factor beta-1 (by 80%) collagen type III alpha-1 (by 71%) and atrial natriuretic factor (by 86%).

CONCLUSIONS

Macrophages mediate the development of hypertension, LVH, adverse cardiac remodeling, and fibrosis. Macrophages, therefore, should be considered as a therapeutic target to reduce the adverse consequences of hypertensive heart disease.

Buyang Huanwu Decoction (BYHWD) Enhances Angiogenic Effect of Mesenchymal Stem Cell by Upregulating VEGF Expression After Focal Cerebral Ischemia

Buyang Huanwu decoction (BYHWD) has been used for centuries to treat paralysis and stroke. Previously, we have demonstrated that BYHWD combined with mesenchymal stem cell (MSC) transplantation attenuates ischemic injury partly by upregulating angiogenesis. However, the mechanisms of this drug for stroke treatment are not completely understood. Here, we aimed to clarify the mechanism of BYHWD on angiogenesis mediated by MSCs. Firstly, we verified microvessels with a size of 50-100 nm produced by either MSCs or MSCs treated by 500 μg/ml BYHWD. These exosomes were purified and found to be able to activate vascular endothelial growth factor (VEGF) expression in endothelial cells (ECs). Moreover, exosomes from MSCs and MSCs treated by BYHWD induced elevated microRNA (miRNA)-126 expression and reduced miR-221 and miR-222 expression. In MSCs, disruption of dicer, an enzyme responsible for miRNA maturation, by dicer small interfering RNA (siRNA), or RNase pretreatment abolished this ability of the exosomes. Additionally, exosomes from MSCs treated by BYHWD promoted VEGF and Ki-67 expression and augmented vascular density in rat brain after bilateral carotid artery ligation. In conclusion, our study revealed that BYHWD exposure augmented angiogenetic miRNA and VEGF expression in exosomes secreted by MSCs and elevated angiogenesis in rat brain.

Angiotensin AT2 receptor stimulation is anti-inflammatory in lipopolysaccharide-activated THP-1 macrophages via increased interleukin-10 production

Macrophages have an important role in the pathogenesis of hypertension and associated end-organ damage via the activation of the Toll-like receptors, such as Toll-like receptor-4 (TLR4). Accumulating evidence suggests that the angiotensin AT2 receptor (AT2R) has a protective role in pathological conditions involving inflammation and tissue injury. We have recently shown that AT(2)R stimulation is renoprotective, which occurs in part via increased levels of anti-inflammatory interleukin-10 (IL-10) production in renal epithelial cells; however, the role of AT(2)R in the inflammatory activity of macrophages is not known. The present study was designed to investigate whether AT(2)R activation stimulates an anti-inflammatory response in TLR4-induced inflammation. The effects of the anti-inflammatory mechanisms that occurred following pre-treatment with the AT(2)R agonist Compound 21 (C21) (1 μmol ml(-1)) on the cytokine profiles of THP-1 macrophages after activation by lipopolysaccharide (LPS) (1 μg ml(-1)) were studied. The AT(2)R agonist dose-dependently attenuated LPS-induced tumor necrosis factor-α (TNF-α) and IL-6 production but increased IL-10 production. IL-10 was critical for the anti-inflammatory effects of AT(2)R stimulation because the IL-10-neutralizing antibody dose-dependently abolished the AT(2)R-mediated decrease in TNF-α levels. Further, enhanced IL-10 levels were associated with a sustained, selective increase in the phosphorylation of extracellular signal-regulated kinase (ERK1/2) but not p38 mitogen-activated protein kinase (MAPK). Blocking the activation of ERK1/2 before C21 pre-treatment completely abrogated this increased IL-10 production in response to the AT(2)R agonist C21, while there was a partial reduction in IL-10 levels following the inhibition of p38. We conclude that AT(2)R stimulation exerts a novel anti-inflammatory response in THP-1 macrophages via enhanced IL-10 production as a result of sustained, selective ERK1/2 phosphorylation, which may have protective roles in hypertension and associated tissue injury.