Hypoxia inducible factor 1α in vascular smooth muscle cells promotes angiotensin II-induced vascular remodeling via activation of CCL7-mediated macrophage recruitment

Critical roles of macrophages in pressure overload-induced cardiac remodeling

Macrophages are integral components of the mammalian heart that show extensive expansion in response to various internal or external stimuli. After the onset of sustained pressure overload (PO), the accumulation of cardiac macrophages through local macrophage proliferation and monocyte migration has profound effects on the transition to cardiac hypertrophy and remodeling. In this review, we describe the heterogeneity and diversity of cardiac macrophages and summarize the current understanding of the important roles of macrophages in PO-induced cardiac remodeling. In addition, the possible mechanisms involved in macrophage modulation are also described. Finally, considering the significant effects of cardiac macrophages, we highlight their emerging role as therapeutic targets for alleviating pathological cardiac remodeling after PO.

Crude Radix Aconiti Lateralis Preparata (Fuzi) with Glycyrrhiza Reduces Inflammation and Ventricular Remodeling in Mice through the TLR4/NF-κB Pathway

Radix Aconiti Lateralis Preparata (Fuzi) is a traditional Chinese medicine. Its alkaloids are both cardiotonic and cardiotoxic; however, the underlying mechanisms are unclear. Compatibility testing and processing are the primary approaches used to reduce the toxicity of aconite preparations. The purpose of this study was to compare the effects of crude Fuzi (CFZ), CFZ combined with Glycyrrhiza (Gancao) (CFZ+GC), and prepared materials of CFZ (PFZ) on heart failure (HF) in C57BL/6J mice and explore the potential mechanisms of action of CFZ. Transverse aortic constriction (TAC) was used to generate the HF state, and CFZ (1.5 g·mL⁻¹), PFZ (1.5 g·mL⁻¹), or CFZ+GC (1.8 g·mL⁻¹) was orally administered to the HF-induced mice daily. For the subsequent 8 weeks, hemodynamic indicators, ventricular pressure indices, and mass indices were evaluated, and histopathological imaging was performed. CFZ, CFZ+GC, and PFZ significantly improved left ventricular function and structure and reduced myocardial damage. CFZ+GC was more effective than CFZ and PFZ, whereas CFZ had higher toxicity than CFZ+GC and PFZ. CFZ and CFZ+GC attenuated ischemia-induced inflammatory responses and also inhibited Toll-like receptor-4 (TLR4) and nuclear factor kappa beta (NF-κB) action in the heart. Moreover, mass spectrometry analysis revealed a decrease in the levels of toxic components of CFZ+GC, whereas those of the protective components were increased. This study suggested that GC reduces the toxicity and increases the efficacy of CFZ on HF induced by TAC. Furthermore, GC+CFZ reduces the risk of HF by ameliorating the inflammation response, which might be partially related to the inhibition of the TLR4/NF-κB pathway.

Oxygen homeostasis and cardiovascular disease: A role for HIF?

Hypoxia, the decline of tissue oxygen stress, plays a role in mediating cellular processes. Cardiovascular disease, relatively widespread with increased mortality, is closely correlated with oxygen homeostasis regulation. Besides, hypoxia-inducible factor-1(HIF-1) is reported to be a crucial component in regulating systemic hypoxia-induced physiological and pathological modifications like oxidative stress, damage, angiogenesis, vascular remodeling, inflammatory reaction, and metabolic remodeling. In addition, HIF1 controls the movement, proliferation, apoptosis, differentiation and activity of numerous core cells, such as cardiomyocytes, endothelial cells (ECs), smooth muscle cells (SMCs), and macrophages. Here we review the molecular regulation of HIF-1 in cardiovascular diseases, intended to improve therapeutic approaches for clinical diagnoses. Better knowledge of the oxygen balance control and the signal mechanisms involved is important to advance the development of hypoxia-related diseases.

DNA N6-methyladenine modification in hypertension

DNA methylation has a role in the pathogenesis of essential hypertension. DNA N6-methyladenine (6mA) modification as a novel adenine methylation exists in human tissues, but whether it plays a role in hypertension development remains unclear. Here, we reported that the global 6mA DNA level in leukocytes was significantly reduced in patients with hypertension and was reversed with successful treatment. Age, systolic blood pressure, and serum total cholesterol and high-density lipoprotein levels were associated with decreased leukocyte 6mA DNA level. Elevated ALKBH1 (AlkB homolog 1), a demethylase of 6mA, level mediated this dynamic change in 6mA level in leukocytes and vascular smooth muscle cells in hypertension mouse and rat models. Knockdown of ALKBH1 suppressed angiotensin II-induced vascular smooth muscle phenotype transformation, proliferation and migration. ALKBH1-6mA directly and negatively regulated hypoxia inducible factor 1 α (HIF1α), which responded to angiotensin II-induced vascular remodeling. Collectively, our results demonstrate a potential epigenetic role for ALKBH1-6mA regulation in hypertension development, diagnosis and treatment.

HIF-hypoxia signaling in skeletal muscle physiology and fibrosis

Hypoxia refers to the decrease in oxygen tension in the tissues, and the central effector of the hypoxic response is the transcription factor Hypoxia-Inducible Factor α (HIF1-α). Transient hypoxia in acute events, such as exercising or regeneration after damage, play an important role in skeletal muscle physiology and homeostasis. However, sustained activation of hypoxic signaling is a feature of skeletal muscle injury and disease, which can be a consequence of chronic damage but can also increase the severity of the pathology and worsen its outcome. Here, we review evidence that supports the idea that hypoxia and HIF-1α can contribute to the establishment of fibrosis in skeletal muscle through its crosstalk with other profibrotic factors, such as Transforming growth factor β (TGF-β), the induction of profibrotic cytokines expression, as is the case of Connective Tissue Growth Factor (CTGF/CCN2), or being the target of the Renin-angiotensin system (RAS).