miR-199a-5p Relieves Obstructive Sleep Apnea Syndrome-Related Hypertension by Targeting HIF-1α

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.

HIF-1α Induced by Hypoxia Promotes Peripheral Nerve Injury Recovery Through Regulating Ferroptosis in DRG Neuron

Peripheral nerve injury (PNI) usually has a poor effect on functional recovery and severely declines the patient's quality of life. Our prior findings indicated that hypoxia remarkably promoted nerve regeneration of rats with sciatic nerve transection. However, the underlying molecular mechanisms of hypoxia in functional recovery of PNI still remain elusive. In this research, we tried to explain the functional roles and mechanisms of hypoxia and the hypoxia-inducible factor-1α (HIF-1α) in PNI. Our results indicated that hypoxia promoted proliferation and migration of dorsal root ganglia (DRG) and increased the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Mechanistically, hypoxia suppressed ferroptosis through activating HIF-1α in DRG neurons. Gain and loss of function studies were performed to evaluate the regulatory roles of HIF-1α in ferroptosis and neuron recovery. The results revealed that up-regulation of HIF-1α enhanced the expression of solute carrier family membrane 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) and increased the contents of cysteine and glutathione, while inhibiting the accumulation of reactive oxygen species (ROS). Our findings provided novel light on the mechanism of ferroptosis involved in PNI and manifest hypoxia as a potential therapeutic strategy for PNI recovery.

Overexpression of miR-199a-5p improves brain injury in newborn rats with intrauterine infection via inhibition of astrocyte activation

White matter injury is the most common form of brain injury in preterm infants. In addition to hypoxia ischemia, intrauterine infection is most closely related to brain white matter injury. Our study aimed to explore the mechanism of the miR-199a-5p/HIF-1α axis on astrocyte activation and brain injury in newborn rats caused by intrauterine infection. The animal/cell model was established via escherichia coli infection/lipopolysaccharide induction, followed by the measurement of body weight, brain weight, and the pathological changes in brain tissues of newborn rats, and the pathological changes in placenta and uterus wall of pregnant rats. Also, the levels of GFAP, TNF-α, MDA, GSH, SOD, miR-199a-5p, and HIF-1α were detected though corresponding assays or kits. In vitro, cell viability and apoptosis and the levels of IL-6 and TNF-α were evaluated in astrocytes. Moreover, the targeting relationship between miR-199a-5p and HIF-1α was verified. miR-199a-5p was lowly expressed in the brain tissues of newborn rats with intrauterine infection. Overexpression of miR-199a-5p relieved the injury of placenta and uterus wall in pregnant rats and brain injury in newborn rats, accompanied by decreased HIF-1α, GFAP, TNF-α, and MDA levels and increased GSH and SOD levels. Results from cell models showed that miR-199a-5p overexpression inhibited astrocyte activation, shown by enhanced cell viability, weakened cell apoptosis, and decreased GFAP, IL-6, and TNF-α. Mechanistically, miR-199a-5p targeted HIF-1α to decrease its expression. Collectively, miR-199a-5p inhibited astrocyte activation and alleviated brain injury in newborn rats with intrauterine infection by reducing HIF-1α expression.

A positive feedback loop between miR-574-3p and HIF-1α in promoting angiogenesis under hypoxia

In our previous report, we presented evidence supporting the role of miR-574-3p in downregulating the expression of cullin 2 (CUL2) in gastric cancer (GC) cells. Expanding on those findings, the present study aims to confirm the direct interaction between miR-574-3p and the 3' untranslated region (3'UTR) of CUL2, which leads to the suppression of CUL2 expression and destabilization of the VCBCR complex. Based on these discoveries, we propose a novel pathway involving miR-574-3p, HIF-1α, and VEGF that contributes to angiogenesis. Through a series of meticulous experiments, we successfully validate this hypothesis. Specifically, our observations indicate that overexpression of miR-574-3p in GC cells induces an upregulation of HIF-1α and VEGF, resulting in enhanced proliferation, migration, invasion, and tube formation of HUVEC cells. Furthermore, employing a mouse model, we demonstrate that miR-574-3p facilitates the recruitment of endothelial cells towards matrigel xenografts. Additionally, we note a parallel increase in miR-574-3p and HIF-1α levels across multiple cell lines (including AGS, SGC-7901, Hela, and 293T cells) subjected to hypoxic conditions (2 % O2 or CoCl2 treatment), as well as in the myocardial muscles of sodium nitrite-induced hypoxic mice. Further investigations reveal that HIF-1α upregulates miR-574-3p expression by directly binding to the miR-574 promoter. Collectively, these findings strongly support the existence of a positive feedback loop between miR-574-3p and HIF-1α, which facilitates angiogenesis under hypoxic conditions.

The role of microRNAs in pathophysiology and diagnostics of metabolic complications in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which is characterized by recurrent apneas and/or hypopneas occurring during sleep due to upper airway obstruction. Among a variety of health consequences, OSA patients are particularly susceptible to developing metabolic complications, such as metabolic syndrome and diabetes mellitus type 2. MicroRNAs (miRNAs) as epigenetic modulators are promising particles in both understanding the pathophysiology of OSA and the prediction of OSA complications. This review describes the role of miRNAs in the development of OSA-associated metabolic complications. Moreover, it summarizes the usefulness of miRNAs as biomarkers in predicting the aforementioned OSA complications.