Hsa_circ_0081065 exacerbates IH-induced EndMT via regulating miR-665/HIF-1α signal axis and HIF-1α nuclear translocation.

CircRNAs play an important role in various physiological and pathological biological processes. Despite their widespread involvement, the function of circRNAs in intermittent hypoxia (IH) remain incompletely understood. This study aims to clarify the molecular mechanism of it in IH. Differentially expressed circRNAs were identified by transcriptome sequencing analysis in intermittent hypoxia (IH) model. GO and KEGG enrichment analys were performed on the identified differentially expressed circRNAs. The circular characteristics of hsa_circ_0081065 in human umbilical vein endothelial cells (HUVECs) were detected by RT-qPCR. The sublocalization of hsa_circ_0081065 was examined by FISH. The effect of hsa_circ_0081065 on endothelial to mesenchymal transition (EndMT) was estimated by detecting the expression of EndMT related markers. Various techniques, including RNA-pull down, RIP, EMSA, dual-luciferase reporter assay and immunofluorescence staining were used to investigate the relationship among hsa_circ_0081065, miR-665 and HIF-1α. A total of 13,304 circRNAs were identified in HUVECs treatment with IH, among which 73 were differentially expressed, including 24 upregulated circRNAs and 49 downregulated circRNAs. Notably, hsa_circ_0081065 demonstrated a significantly upregulation. Hsa_circ_0081065 exhibited the circular characteristics of circRNA and was predominantly localized in the cytoplasm. Knockdown of hsa_circ_0081065 inhibited EndMT. Mechanically, we demonstrated that hsa_circ_0081065 acts as a sponge for miR-665 to up-regulate HIF-1α and exacerbate HIF-1α nuclear translocation in HUVECs. We have demonstrated that hsa_circ_0081065 is significantly upregulated in HUVECs treated with IH. Our findings indicate that hsa_circ_0081065 exacerbates IH-induced EndMT through the regulation of the miR-665/HIF-1α signal axis and facilitating HIF-1α nuclear translocation. These results provide a theoretical basis for considering of EndMT as a potential therapeutic target for OSAHS intervention.

Oscillating field stimulation promotes axon regeneration and locomotor recovery after spinal cord injury.

Oscillating field stimulation (OFS) is a potential method for treating spinal cord injury. Although it has been used in spinal cord injury (SCI) therapy in basic and clinical studies, its underlying mechanism and the correlation between its duration and nerve injury repair remain poorly understood. In this study, we established rat models of spinal cord contusion at T10 and then administered 12 weeks of OFS. The results revealed that effectively promotes the recovery of motor function required continuous OFS for more than 6 weeks. The underlying mechanism may be related to the effects of OFS on promoting axon regeneration, inhibiting astrocyte proliferation, and improving the linear arrangement of astrocytes. This study was approved by the Animal Experiments and Experimental Animal Welfare Committee of Capital Medical University (supplemental approval No. AEEI-2021-204) on July 26, 2021.

Early electrical field stimulation prevents the loss of spinal cord anterior horn motoneurons and muscle atrophy following spinal cord injury.

Our previous study revealed that early application of electrical field stimulation (EFS) with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury (SCI). The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T10. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov's motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.

Protective effect of sphingosine-1-phosphate for chronic intermittent hypoxia-induced endothelial cell injury.

Intermittent hypoxia (IH) induced by obstructive sleep apnea (OSA) is the key factor in oxidative stress and the concomitant inflammation of endothelial cells (ECs). In recent years, the lipid sphingosine-1-phosphate (S1P) has been reported to probably play a central role in inflammatory diseases. However, its role in IH-induced endothelial injury remains uncertain. In this study, we investigated the IH-induced ECs inflammation and apoptosis, as well as the role of S1P in both. First, human umbilical vein endothelial cells (HUVECs) were treated with IH to explore the mechanism of S1P and S1P microbubbles (S1P-MBs) in HUVECs with altered function. The intracellular reactive oxygen species (ROS) significantly increased after IH treatment, which further resulted in the increased efficiency of cell apoptosis. Following the S1P and S1P-MBs treatments, the lower Bax protein and Cyt c protein levels in HUVECs indicated the protective effects of S1P for CIH-induced ECs injury. The reason may be that the enhanced expression levels of Gα(i) and S1P receptor 1 in S1P and S1P-MBs treatment groups could actively increase intracellular p-Akt and p-eNOS protein levels, which counteract the increased ROS secondary to inflammation from IH. Therefore, the Akt/eNOS signaling pathway induced by S1P may be important in protecting IH-induced ECs injury. Furthermore, the S1P-MBs may be designed as a novel S1P dosage formulation to protect the body from the ECs injuries in the future.

Prolyl 4-Hydroxylase Domain Protein 3 Overexpression Improved Obstructive Sleep Apnea-Induced Cardiac Perivascular Fibrosis Partially by Suppressing Endothelial-to-Mesenchymal Transition.

BACKGROUND: Intermittent hypoxia (IH) induced by obstructive sleep apnea is the key factor involved in cardiovascular fibrosis. Under persistent hypoxia condition, endothelial cells respond by endothelial-to-mesenchymal transition (EndMT), which is associated with cardiovascular fibrosis. Prolyl 4-hydroxylase domain protein 3 (PHD3) is a cellular oxygen sensor and its expression increased in hypoxia. However, its role in obstructive sleep apnea-induced EndMT and cardiovascular fibrosis is still uncertain. We investigated the potential mechanism of obstructive sleep apnea-induced cardiac perivascular fibrosis and the role of PHD3 in it. METHODS AND RESULTS: In vivo, C56BL/6 mice were exposed to IH for 12 weeks. PHD3 expression was changed by lentivirus-mediated short-hairpin PHD3 and lentivirus carrying PHD3 cDNA. EndMT related protein levels, histological and functional parameters were detected after 12 weeks. In vitro, human umbilical vein endothelial cells were treated with IH/short-hairpin PHD3/lentivirus carrying PHD3 cDNA to explore the mechanism of PHD3 in altered function of human umbilical vein endothelial cells. We found that chronic intermittent hypoxia increase PHD3 expression and EndMT. In vivo, IH accelerate cardiac dysfunction and aggravate collagen deposition via the process of EndMT. And, when PHD3 were overexpressed, cardiac dysfunction and collagen excessive deposition were improved. In vitro, IH induced EndMT, which endow human umbilical vein endothelial cells spindle morphology and an enhanced ability to migration and collagen secretion. PHD3 overexpression in cultured human umbilical vein endothelial cells ameliorated IH-induced EndMT through inactivating hypoxia-inducible factor 1 alpha and small mothers against decapentaplegic 2 and 3. CONCLUSIONS: Obstructive sleep apnea-induced cardiac perivascular fibrosis is associated with EndMT, and PHD3 overexpression might be beneficial in the prevention of it by inhibiting EndMT. PHD3 overexpression might have therapeutic potential in the treatment of the disease.

Poly(ADP-ribose)polymerase 1 inhibition protects against age-dependent endothelial dysfunction.

Age-related endothelial dysfunction is closely associated with the local production of reactive oxygen species (ROS) within and in the vicinity of the vascular endothelium. Oxidant-induced DNA damage can activate the nuclear enzyme poly(ADP-ribose) polymerase 1 (PARP-1), leading to endothelial dysfunction in various pathophysiological conditions. The present study aimed to investigate the role of PARP-1 in age-dependent changes in endothelial cell function and its underlying mechanism. Wild-type (WT) and PARP-1(-/-) mice were divided into young (2 months) and old (12 months) groups. Isolated aortic rings were suspended to record isometric tension to assess endothelial function. Nitric oxide (NO) production and content in plasma were detected by spectrophotometry. Superoxide (O2(-) production was detected by dihydroethidium. Expression of PARP-1, endothelial nitric oxide synthase (eNOS), induced nitric oxide synthase (iNOS), and arginase-2 (Arg2) was assessed by western blot analysis. Endothelium-dependent relaxation in response to acetylcholine was lost in old WT, but not PARP-1(-/-), mice. Endothelium-independent vasodilation was not impaired in aging mice. Production of O2(-) was greater in aging WT mice than young or aging PARP-1(-/-) mice. eNOS expression was not affected by aging in WT or PARP-1(-/-) mice, but p-eNOS expression decreased and iNOS and Arg2 levels were upregulated only in aging WT mice. In conclusion, PARP-1 inhibition may protect against age-dependent endothelial dysfunction, potentially by regulating NO bioavailability via iNOS. Inhibition of PARP-1 may help in vascular aging prevention.

Glucagon-Like Peptide 1 Protects against Hyperglycemic-Induced Endothelial-to-Mesenchymal Transition and Improves Myocardial Dysfunction by Suppressing Poly(ADP-Ribose) Polymerase 1 Activity.

Under high glucose conditions, endothelial cells respond by acquiring fibroblast characteristics, that is, endothelial-to-mesenchymal transition (EndMT), contributing to diabetic cardiac fibrosis. Glucagon-like peptide-1 (GLP-1) has cardioprotective properties independent of its glucose-lowering effect. However, the potential mechanism has not been fully clarified. Here we investigated whether GLP-1 inhibits myocardial EndMT in diabetic mice and whether this is mediated by suppressing poly(ADP-ribose) polymerase 1 (PARP-1). Streptozotocin diabetic C57BL/6 mice were treated with or without GLP-1 analog (24 nmol/kg daily) for 24 wks. Transthoracic echocardiography was performed to assess cardiac function. Human aortic endothelial cells (HAECs) were cultured in normal glucose (NG) (5.5 mmol/L) or high glucose (HG) (30 mmol/L) medium with or without GLP-1analog. Immunofluorescent staining and Western blot were performed to evaluate EndMT and PARP-1 activity. Diabetes mellitus attenuated cardiac function and increased cardiac fibrosis. Treatment with the GLP-1 analog improved diabetes mellitus-related cardiac dysfunction and cardiac fibrosis. Immunofluorescence staining revealed that hyperglycemia markedly increased the percentage of von Willebrand factor (vWF)(+)/alpha smooth muscle actin (α-SMA)(+) cells in total α-SMA(+) cells in diabetic hearts compared with controls, which was attenuated by GLP-1 analog treatment. In cultured HAECs, immunofluorescent staining and Western blot also showed that both GLP-1 analog and PARP-1 gene silencing could inhibit the HG-induced EndMT. In addition, GLP-1 analog could attenuate PARP-1 activation by decreasing the level of reactive oxygen species (ROS). Therefore, GLP-1 treatment could protect against the hyperglycemia-induced EndMT and myocardial dysfunction. This effect is mediated, at least partially, by suppressing PARP-1 activation.

Design of site-directed magnetic targeting system in acute spinal cord injury.

Effective repair immediately after spinal cord injury can improve the prognosis of the patient. Injection of membrane resealing nanomaterial is one of the most promising technique to repair the membrane. In order to improve the retention rate of membrane repair material at injury site, membrane resealing nanomaterial can be combined with magnetic nanoparticle and magnetic targeting system. In this paper, a special site directed magnetic targeting system, which contain a C-shaped permanent magnet and a ferromagnetic needle, was constructed. Simulation was conducted to analyze the influence of the shape of needle on the magnetic field to provide magnetic force large enough to make the magnetic particles stay at the target site. Results showed that the appearance of ferromagnetic needle raised both the strength and the gradient of magnetic field at the target site. Moreover, with similar apex angles, longer needles with larger diameters can produced lager magnetic field, but smaller needles has better focal area at the small injury site in spinal cord injury. These results provide a basis for design and fabrication of ferromagnetic needles when the targeting system is applied in future experiments.