apelin-13-peptide and Hypoxia

Apelin and its receptor angiotensin receptor - like 1 (APJ) are closely related to renal fibrosis, but their specific roles in renal fibrosis are still controversial. In this article, we discussed the role of Apelin/APJ system in renal fibrosis and its mechanism.. Chronic intermittent hypoxia (CIH) rat model was established to induce the environment of renal fibrosis and a competitive antagonist of the APJ receptor ML221 was administered to CIH rats. The rats were divided into Control, CIH and ML221 groups. HE staining was used to detect the inflammatory injury and fibrosis of renal tissue. The expressions of renal fibrosis-related indicators transforming growth factor-β (TGF-β), α-smooth muscle actin (α-SMA) and Human type I collagen (Col-Ⅰ) were detected by immunohistochemistry. The levels of oxidative stress indexes reactive oxygen species (ROS), Malondialdehyde (MDA), Superoxide Dismutase (SOD) and inflammation-related indexes Interleukin (IL) -6, tumor necrosis factor-α (TNF-α) and IL-1β were detected by ELISA. At the same time, the levels of Apelin-13 and AngiotensinII (AngⅡ) were also measured by ELISA. Finally, western blot was used to detect the expression of Apelin pathway and renal fibrosis-related proteins. In addition, at the cellular level, we divided the cells into Control, CIH, Apelin-13 and Apelin-13+ML-221 groups to further verify the specific mechanisms at the cellular level.. The expression of Apeline-13 and its related pathways was significantly increased after the induction of CIH in rats. However, the degree of renal fibrosis in ML221 group was further significantly increased after inhibiting the expression of Apelin. At the cellular level, CIH model cells treated with Apelin-13 significantly reduced cell proliferation, oxidative stress and inflammatory response, and decreased the expression of fibrosis-related proteins, which can be reversed by ML221 administration.. The increased reactivity of Apelin may be one of the protective mechanisms against renal fibrosis induced by CIH.

Topics: Angiotensin II; Animals; Apelin; Apelin Receptors; Cell Line; Fibrosis; Humans; Hypoxia; Inflammation; Intercellular Signaling Peptides and Proteins; Kidney; Kidney Diseases; Male; Nitrobenzoates; Oxidative Stress; Pyrans; Rats, Wistar

Hypoxic pretreatment of peripheral blood mononuclear cells (PBMNCs) enhances therapeutic angiogenesis in ischemic tissues after cell transplantation. However, newly formed vessels generated using this approach are immature and insufficient for promoting functional recovery from severe ischemia. In this study, we examined whether apelin-13, a regulator of vessel maturation, could be an effective promoter of therapeutic angiogenesis, following severe limb ischemia. Combinatorial treatment of hypoxic preconditioned PBMNCs with apelin-13 resulted in increased blood perfusion and vascular reactivity in ischemic mouse hindlimbs compared with a monotherapy comprising each factor. Apelin-13 upregulated expression of PDGF-BB and TGF-β1 in hypoxic PBMNCs, as well as that of PDGFR-β in vascular smooth muscle cells (VSMCs). Proliferation and migration of VSMCs treated with apelin-13 was accelerated in the presence of PDGF-BB. Interestingly, expression of an apelin receptor, APJ, in PBMNC was increased under hypoxia but not under normoxia. In addition, an in vitro angiogenesis assay using a co-culture model comprising mouse thoracic aorta, hypoxic PBMNCs, and apelin-13 demonstrated that combinatorial treatment recruited mural cells to sprouted vessel outgrowths from the aortic ring, thereby promoting neovessel maturation. Thus, combinatorial injection of hypoxic PBMNCs and apelin-13 could be an effective therapeutic strategy for patients with severe ischemic diseases.

Topics: Animals; Apelin Receptors; Cell Movement; Cell Proliferation; Cell Transplantation; Cell- and Tissue-Based Therapy; Combined Modality Therapy; Disease Models, Animal; Gene Expression; Hindlimb; Hypoxia; Intercellular Signaling Peptides and Proteins; Ischemia; Ischemic Preconditioning; Leukocytes, Mononuclear; Male; Mice; Neovascularization, Physiologic; Receptors, G-Protein-Coupled

To study the role of apelin in the prevention of pulmonary hypertension induced by hypoxia in rats.. The animal model of hypoxic pulmonary hypertension was established by exposing the rats to isobaric hypoxic chamber for 4 weeks (8 h/d, 6 d/ w). Forty male Sprague-Dawley rats were randomly divided into control group (NC), hypoxic group(HH), hypoxic with low-dose apelin (5 nmol/(kg x d) group(LA) and high-dose apelin (10 nmol/(kg x d) (HA). [pGlu]apelin-13 was administered into the rats of apelin groups by mini-osmotic pump subcutaneously. The mean pulmonary arterial pressure(mPAP) and the mean carotid arterial pressure (mCAP) were measured by either right or left cardiac catheterization, and the weight ratio of right ventricule/left ventricule plus septum (RV/(LV + S)) were calculated. The Masson's trichrome stained lung specimens were examined by light microscope to examine the vessel wall area/total area (WA/TA), vessel cavity area/total area (CA/TA) and media thickness of pulmonary arterioles (PAMT). Meanwhile, the lung homogenates were assayed for the activity of supeeroxide dismutase (SOD) and the content of malondialdehyde (MDA).. (1) mPAP and RV/(LV + S) of HH group were significantly higher than those of NC group. mPAP of LA and HA groups were lower than those of HH group. The RV/(LV + S) of HA group was significantly lower than that of HH group, but there was no significant difference between HH group and LA group. (2) Masson's trichrome staining revealed that WA/TA and PAMT of HH group were higher than those of NC group. Administration of apelin significantly eliminated WA/TA and PAMT in LA and HA groups. (3) CA/TA of HH group was lower than that of NC group. Administration of apelin significantly elevated CA/TA in LA and HA groups. (4) The activity of SOD and content of MDA in HH group was, respectively, lower and higher than those in NC group. Apelin treatment increased the activity of SOD in LA and HA groups while decreased the content of MDA.. Apelin could play an important role in treatment of hypoxic pulmonary hypertension of rats and the mechanisms of protection were associated with vasodilation of pulmonary artery and inhibition of oxidative stress.

Topics: Animals; Cardiotonic Agents; Hypertension, Pulmonary; Hypoxia; Intercellular Signaling Peptides and Proteins; Male; Oxidative Stress; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Vasodilation

To investigate the effectiveness and mechanism of apelin against pulmonary hypertension and pulmonary vascular remodeling induced by hypoxia in rats, 24 male Sprague-Dawley rats were randomly divided into normal control (NC) group, 4-week hypoxia (HH) group and 4-week hypoxia with apelin (HA) group (each n=8). The rats of hypoxic group were placed in an isobaric hypoxic chamber, in which O₂ and CO₂ content was maintained at 9%-11% and <3%, respectively, for 4 weeks (8 h/d, 6 d/week). [pGlu]apelin-13 (10 nmol/kg per day, 28 d) was administered subcutaneously by osmotic mini-pump before hypoxia treatment in HA group. L-arginine (L-Arg) uptake of pulmonary artery was assay by [³H]-L-Arg, while nitric oxide synthase (NOS) activity of pulmonary tissue, and nitrate/nitrite (NO₂(-)/NO₃(-)) concentrations in pulmonary tissue and plasma were detected by colorimetric technique and nitrate reductase method, respectively. The results showed that mean pulmonary arterial pressure, the ratio value of right ventricle weight to left ventricle plus septum weight, the relative medial thickness, and the relative medial area of pulmonary arterioles were higher in HH group than those in NC group (all P<0.01), while these indices were lower in HA group than those in HH group (P<0.05 or P<0.01). Compared with those in HH group, the uptake of 0.5, 5 and 10 nmol/L [³H]-L-Arg in pulmonary artery in HA group increased by 121.4% (P<0.01), 85.0% (P<0.05) and 61.5% (P<0.05), respectively; cNOS activity of pulmonary tissue increased by 74.3%, while iNOS activity decreased by 25.0% (all P<0.01); and NO₂(-)/NO₃(-) concentrations in pulmonary tissue and plasma increased by 97.6% and 48.0% (all P<0.05), respectively. Taken together, our results suggest that apelin has a prophylactic effect against hypoxic pulmonary hypertension in rats, and that the mechanism of this effect is possibly associated with activation of the L-Arg/NOS /NO pathway.

Topics: Animals; Arginine; Heart Ventricles; Hypertension, Pulmonary; Hypoxia; Intercellular Signaling Peptides and Proteins; Male; Nitric Oxide Synthase Type II; Pulmonary Artery; Rats; Rats, Sprague-Dawley; Signal Transduction