Correlative cell signaling pathway for expression of heme oxygenase-1 induced by ginkgo biloba extract in rat vascular smooth muscle cells

AIM: To explore the effects of heme oxygenase-1(HO-1) protein expression induced by ginkgo biloba extract (EGB761) in rat vascular smooth muscle cells (RVSMC) and the correlative cell signaling pathway.METHODS: The RVSMC lines were revived.Serial passage to 6 generation was carried out and divided into different groups.The cells were treated respectively with vehicle,purely EGB761,EGB761 plus zinc protoporphyrin IX or other specific inhibitors of cell signaling pathway.Western blotting method was used to detect the expression of HO-1 in RVSMC.RESULTS: EGB761 induced HO-1 protein expression in a dose dependent manner.ZnPPⅨ and genitein significantly inhibited HO-1 protein expression induced by EGB761 (0.10±0.01,0.07±0.01 vs 0.61±0.07,P<0.01,respectively).However,calphostin-C,LY294002,Bay11- 7082 had no apparent effects on HO-1 protein expression induced by EGB761 (0.63±0.07,0.65±0.07,0.64±0.06 vs 0.61±0.07,P>0.05,respectively).CONCLUSION: (1) EGB761 significantly induces HO-1 protein expression in RVSMC,and the effect can be inhibited by a specific HO inhibitor ZnPPⅨ.(2) The HO-1 protein expression induced by EGB761 in RVSMC is mediated by tyrosine protein kinase pathway.     

Cloning and sequencing of encoding region of heme oxygenase-1 gene from Tibetan antelope

AIM: To clone and analyze the encoding region of heme oxygenase-1(HO-1) gene from Tibetan antelope(Pantholops hodgsonii). METHODS:The total RNA was isolated from the liver of Tibetan antelope and the HO-1 gene was amplified by RT-PCR. The PCR product was cloned into pGEM-T vector and sequenced. The nucleotide sequences were compared with the data from GenBank by BLAST method. RESULTS:The encoding region of HO-1 gene from Tibetan antelope was obtained and deposited in GenBank as accession number JQ809687. The encoding sequence was 897 bp in full length, which encoded 298 amino acids. Sequence similarity analysis showed that the HO-1 gene cloned from Tibetan antelope shared 98% and 96% in the nucleotides, and shared 92% and 97% in the amino acids with those of Capra hircusand Bos taurus, respectively. The sequence similarity of nucleotides and amino acids also shared 86% and 87% with other vertebrates, which were highly conservative. The molecular phylogenetic tree based on the amino sequence of HO-1 showed that Tibetan antelope and Capra hircus was classified to one cluster, which was basically concerted to the evolutionary relationship of traditional species. CONCLUSION:The encoding region of Tibetan antelope HO-1 gene is successfully cloned, which provides a foundation for exploring the molecular and biological mechanisms of high altitude adaptation and cell protection in Qinghai-Tibet Plateau species under hypoxic condition.     

Cloning and sequencing of heme oxygenase-1 gene from Ochotona curzo-niae

[ABSTRACT] AIM: To clone and analyze the heme oxygenase-1 (HO-1) gene from Ochotona curzoniae (plateau pika). METHODS: The cDNA of HO-1 was cloned by RT-PCR and rapid amplication of cDNA ends (RACE) from the liver of Ochotona curzoniae. The bioinformatic analysis of HO-1 gene was performed. RESULTS: The cDNA of HO-1 gene in Ochotona curzoniae was obtained. The data of the sequence was deposited into GenBank and the accession number is JX035934. The full length of cDNA was 1 466 bp, including 873 bp encoding sequence (290 amino acids). Homology comparison showed that the DNA sequence of the HO-1 gene was highly homologous with Oryctolagus cuniculus (89%), Homo sapiens (87%), Bos taurus (85%), Mus musculus (79%), Rattus norvegicus (84%), Sus scrofa (85%) and Equus caballus (85%), and the amino acid sequence of HO-1 was identified with the homology of 89%, 85%, 84%, 80%, 79%, 82% and 67%, respectively. Phylogenetic analysis suggested that the structure of HO-1 was highly similar to that in Oryctolagus cuniculus. CONCLUSION: The HO-1 gene of Ochotona curzoniae was successfully cloned and provides essential information for elucidating the possible roles of HO-1 in adapting of Ochotona curzoniae to extremely high altitude.     

Protective effect of A. auricula-judae extracts on liver function in septic rats

AIM: To explore the effects of Auricularia (A.) auricula-judae extracts on the liver function in septic rats. METHODS: Forty male Wistar rats were randomly divided into control group, model group, A. auricula-judae polysaccharide group and A. auricula-judae crude extract group. Septic model was induced by the procedure of cecal ligation and puncture (CLP). Intragastric administration was performed every 8 h 3 days prior to CLP. The plasma levels of alanine aminotransferase(ALT), aspartate aminotransferase(AST), endotoxin(ET), tumor necrosis factor α(TNF-α), interleukin 6(IL-6) and IL-1β were detected 12 h after CLP. The specimens of the liver were collected to observe the pathological changes. The expression of NF-κB in the liver tissues was detected by the method of immunohistochemistry. RESULTS: Compared with the CLP rats, the intervention of A. auricula-judae polysaccharide and A. auricula-judae crude extract to the septic rats significantly decreased the serum levels of ALT, AST, ET, TNF-α, IL-1β and IL-6 (P<005). The pathological changes of the liver tissues in treatment groups were significantly attenuated compared with CLP group. CONCLUSION: A. auricula-judae polysaccharide and A. auricula-judae crude extract protect liver against sepsis-induced injury by inhibiting the systemic inflammatory response.     

Riboflavin preconditioning alleviates hepatic ischemia/reperfusion injury in rats

AIM: To explore the protective effect of riboflavin preconditioning on hepatic ischemia/reperfusion injury in rats. METHODS: Twenty-four Sprague-Dawley rats wererandomly divided into 3 groups (n=8): sham group, ischemia/reperfusion (I/R) group and riboflavin preconditioning (R+I/R) group. The rats in sham group and I/R group received a standard chow,while the rats in R+I/R group received a chow supplemented with riboflavin. After 4 weeks, portal vein and hepatic artery supplying the middle and left hepatic lobes were clamped with a traumatic vascular clip for induction of partial hepatic ischemia in the rats in I/R group and R+I/R group. After 1 h of ischemia, 1 h of reperfusion was conducted by removal of the clip. The activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum,the activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in serum and liver were measured. Western blotting was employed to examine the protein expression of heme oxygenase-1(HO-1) in the liver. RESULTS: The results showed that ischemia/reperfusion injury markedly increased the activity of AST and ALT in serum, decreased the activity of SOD, and elevated the level of MDA and the activity of HO-1 in the liver as compared with sham group (P<0.01). The riboflavin pretreatment significantly decreased the activity of AST and ALT in serum, increased the activity of SOD and decreased the levels of MDA in serum and liver as compared with I/R group (P<0.01). In addition, the protein expression of HO-1 and the activity of HO-1 were elevated in R+I/R group (P<0.01). Cytoplasmic vacuolation and swelling of the hepatocytes were observed in I/R group. Treatment with riboflavin markedly alleviated the changes of liver structure. CONCLUSION: Riboflavin preconditioning has protective effect on hepatic ischemia/reperfusion injury. The mechanism may be correlated with enhancing the anti-oxidation and alleviating the reaction of lipid peroxidation.     

The expression of heme oxygenase-1 in vascular smooth muscle cells induced by lipopolysaccharide

AIM:To study the alterations of heme oxygenase-1 mRNA in vascular smooth muscle cells(VSMC) induced by lipopolysaccharide(LPS) and the role of heme oxygenase(HO)/carbon monoxide(CO)pathway in the disorders of regulation of cardiovascular system by LPS. METHODS: LPS (final concentrations 10 mg/L,30 mg/L and 50 mg/L) was added in cultured VSMCs for 6 h respectively or 10 mg/L LPS for 9 h and 18 h. MDA content, LDH release and the rate of trypan blue uptake of VSMC were measured. HO-1 mRNA expression was examined by Northern Blot. RESULTS:VSMC HO-1 mRNA expression was increased gradually with the increasing of LPS concentration. When final concentration of LPS was 50 mg/L, the HO-1 mRNA expression of VSMC was increased by 176.7% compared with control. When LPS final concentration was 10 mg/L, the HO-1 mRNA expression increased gradually along with the culture time. When cultured for 18 h, the HO-1 mRNA expression of VSMC was increased by 195.6% compared with control. Only at LPS 50 mg/L for 6 h and 10 mg/L for 18 h, the rate of trypan blue uptake,MDA content and LDH release were significantly increased. CONCLUSION: LPS can induce the HO-1 mRNA expression of VSMC and that were dose-dependent and time-dependent. The inducible HO may play an important role in the pathogenesis of vascular system under LPS.     

Effects of microglia-derived IL-1β on differentiation of OPCs in corpus callosum of septic neonatal rats

AIM: To explore whether IL-1β inhibits the oligodendrocyte precursor cell (OPCs) differentiation and affects axonal myelination. METHODS: One-day-old SD rats were randomly divided into control group and LPS group (48 rats in each group). The rats in LPS group were intraperitoneally injected with 1 mg/kg LPS. The rats in control group were injected with an equal volume of PBS. The rats in each group were further divided into 3 h, 24 h, 3 d, 7 d, 14 d and 28 d subgroups after injection. The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d was determined by double immunofluorescence and Western blotting. The myelin basic protein(MBP) expression in the rat corpus callosum at 14 d, 28 d after injection was also measured. In vitro, primary OPCs culture was performed and divided into control group, 30 μg/L IL-1β group, 30 μg/L IL-1β+IL-1Ra group and 30 μg/L IL-1Ra group. The expression of MBP in the OPCs induced differentiation for 3 d was observed by double immunofluorescence and Western blotting. RESULTS: The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d after LPS injection was obviously increased and the expression of MBP in the rat corpus callosum at 14 d, 28 d in LPS group was obviously decreased compared with control group in vivo. The level of MBP was significantly decreased after IL-1β treatment for 3 d in vitro. However, IL-1Ra (IL-1R inhibitor) reversed the down-regulation of MBP expression. IL-1β inhibited the expression of p-ERK, ERK over-expression reversed the down-regulation of MBP expression compared with IL-1β group. CONCLUSION: IL-1β inhibits the differentiation of OPCs, which may be involved in ERK pathways, thus leading to axonal hypomyelination in the corpus callosum of septic neonatal rats.     

Effects of caveolin-1 scaffolding domain peptide on LPS-induced acute lung injury in mice

AIM: To investigate the effects of caveolin-1 (Cav-1) scaffolding domain peptide, cavtratin, on lipopolysaccharide (LPS)-induced mouse acute lung injury and heme oxygenase-1 (HO-1) activity. METHODS: Adult male BALB/c mice were randomly divided into 6 groups (n=8 to 10):control, Antennapedia internalization sequence (AP), LPS, LPS+hemin, LPS+ hemin+cavtratin and LPS+hemin+cavtratin+zinc protoporphyrin IX (ZnPP) groups. After LPS administration for 24 h, the lung pathological changes, the wet/dry weight (W/D) ratio of lung tissues, total cell number in bronchoalveolar lavage fluid and serum lactate dehydrogenase activity were measured. The co-localization of HO-1 and Cav-1 was displayed by immunofluorescence, and the HO-1 activity were detected. The mRNA expression of pro-inflammatory cytokines IL-1β, IL-6, TNF-α, MCP-1 and iNOS was detected by real-time PCR. RESULTS: The mice in LPS+hemin+cavtratin group had the decreased interaction between HO-1 and Cav-1, and the increased HO-1 activity compare with LPS group (P<0.05). Compared with LPS group, the pulmonary damage was attenuated in LPS+hemin+cavtratin group, and the injury indexes, including W/D ratio, total cell number in bronchoalveolar lavage fluid and lactate dehydrogenase activity in the serum, and the mRNA expression of inflammatory cytokines all decreased (P<0.05). HO-1 activity inhibitor ZnPP abolished the above protective effect of cavtratin on the lung tissues with LPS-induced acute lung injury. CONCLUSION: Cavtratin has beneficial effects on the lung with LPS-induced acute injury by restoring the HO-1 activity.     

Effects of rhynchophylline on adriamycin-induced renal injury in rats

AIM: To explore the effects of rhynchophylline (RHL) on rat renal injury induced by adriamycin. METHODS: Fifty-two female SD rats were randomly divided into normal saline group (NSG, n=10), model group (MG, n=14), low-dose RHL treatment group (RHL-LG, n=14) and high-dose RHL treatment group (RHL-HG, n=14). The animals in the latter 3 groups were injected with adriamycin at a dose of 5 mg/kg through the tail vein. The animals in RHL-LG and RHL-HG were treated with RHL at doses of 5 mg/kg and 15 mg/kg, respectively, by intraperitoneal injection for 8 weeks. The animals in NSG and MG were treated with normal saline only. Urine and blood samples were collected to detect the urine protein, blood urea nitrogen (BUN) and serum creatinine (SCr). The renal tissues of the animals were collected for detection of malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, pathological changes and mRNA expression of angiotension Ⅱreceptors 1,2 (AT_1,2-R), angiotensin-converting enzyme (ACE) and angiotensinogen (AGT). RESULTS: The urine protein, BUN and SCr in RHL-LG were significantly lower than those in MG, but higher than those in RHL-HG (P<0.05). The SOD activity in MG was significantly lower than that in RHL-LG in the renal tissues. The SOD activity in RHL-LG was significantly lower than that in RHL-HG (P<0.05), but the content of MDA was on the contrary. The renal pathological damages in RHL-LG were weaker than that in MG, and that in RHL-HG were weaker than that in RHL-LG. The mRNA expression of AT₁-R, ACE and AGT in MG was significantly higher than that in RHL-LG in the renal tissues, and that in RHL-LG was higher than that in RHL-HG (P<0.05). The mRNA expression of AT₂-R in MG was significantly lower than that in RHL-LG, and that in RHL-LG was significantly lower than that in RHL-HG (P<0.05). CONCLUSION: RHL reduces adriamycin-induced renal injury in rats by attenuating the injury of lipid peroxidation in renal tissue, regulating the mRNA expression of AT_{1, 2}-R, ACE and AGT, and increasing renal blood flow.     

Effect of diltiazem on heme oxygenase-1 and nitric oxide synthase in rats with pulmonary hypertension

AIM: To investigate the action of diltiazem (a calcium antagonist) on the expression of heme oxygenase (HO) -1 and nitric oxide synthase (NOS) in the small pulmonary arteries (SPA) of rat in chronic hypoxia. METHODS: Chronic pulmonary arterial hypertension models were established by treating the rats in hypoxic environment for 6 weeks. After 2 weeks of hypoxia, rats were treated with diltiazem (15 mg/kg/day). Right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were measured. Pathological changes in the lungs were observed under the light microscope and transmission electron microscope. The expression and distribution of heme oxygenase (HO) -1, endothelial NOS (eNOS) and inducible NOS (iNOS) were tested by immunohistochemistry and Western blot. Guanosine-3', 5'-cyclic monophosphate (cGMP) of lung tissues were detected with radioimmunoassay. RESULTS: Diltiazem significantly decreased abnormal RVSP, and RVHI in model rats, attenuated the SPA media thickeness, and recovered abnormal eNOS and iNOS expression in SPA. Whereas diltiazem had little effect on the increased HO-1 expression in SPA caused by hypoxia and ultrastructure injury in endothelium. cGMP levels were corresponded with HO-1. CONCLUSION: Diltiazem has a significant effect on inhibiting hypoxic pulmonary hypertension structural remodeling. These effects might be partly attributed to the suppression of iNOS, promotion of eNOS, and not attenuation HO-1 expression in the lung of hypoxic rats.     

Relationship between expression of heme oxygenase-1 mRNA and pulmonary hypertention induced by hypoxic hypercapnia

AIM: To study the effect of chronic hypoxic hypercapnia on expression of heme oxygenase-1 (HO-1). METHODS: Sprague-Dawley rats were randomly divided into three groups: control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+hemin group(C). HO-1 and HO-1 mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization. RESULTS: ① mPAP and weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were significantly higher in rats of B group than those of A and C group (P<0.01). Differences of mCAP were not significant in three groups(P>0.05). ② Blood CO concentration was significantly higher in rats of B group than that of A group (P<0.01), it was much higher in C group than that of B group(P<0.01). ③ Light microscopy showed that vessel well area/total area (WA/TA), density of medial smooth muscle cell (SMC) and media thickness of pulmonary arterioles were much higher in rats of B group than those of A and C group (P<0.01). ④ The observation by electron microscopy showed proliferation of medial smooth muscle cells and collageous fibers of pulmonary arterioles in rats of B group, hemin could reverse the changes mentioned above. ⑤ HO-1 and HO-1 mRNA in pulmonary arterioles was significantly higher in rats of B group than those of A group(P<0.01), and they were significantly higher in rats of C group than those of B group (P<0.01). CONCLUSION: Expression of HO-1 mRNA and HO-1 in pulmonary arterioles was enhanced by hypoxic hypercapnia. Hemin partly inhibited pulmonary hypertension and pulmonary vessel remodeling by enhancing the expression of HO-1 mRNA and HO-1.     

Protective effects of sulforaphane on retinal neurons in diabetic rats

AIM: To clarify whether sulforaphane (SF) has protective effects on retina neuronal cells in diabetic rats and to identify the related mechanisms involved in this process. METHODS: The diabetic rat model was induced by single intraperitoneal injection of streptozotocin (STZ). The protective effects of SF were evaluated by measuring the generation of reactive oxygen species (ROS), detecting apoptosis of retina neuronal cells with TUNEL staining and counting the survival retinal ganglion cells (RGCs). The nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) and the protein expression of heme oxygenase-1 (HO-1) were examined by immunofluorescence analysis and Western blot. RESULTS: SF treatment significantly attenuated ROS generation, decreased the apoptosis of retina neuronal cells and increased the numbers of survival RGCs in the diabetic rats. Meanwhile, SF significantly increased the nuclear accumulation of Nrf2 and the protein level of HO-1 in the retinas of diabetic rats. However, HO-1 inhibitor, protoporphyrin IX zinc (Ⅱ) diminished the inhibitory effects of SF on RGCs apoptosis. CONCLUSION: SF partially exerts the beneficial neuroprotective effects via the activation of the Nrf2/HO-1 antioxidant pathway, therefore alleviating retinal oxidative stress and decreasing the apoptosis of retina neuronal cells.     

Glucagon-like peptide-1 protects against cardiac microvascular injury in diabetic rats via Keap1-Nrf2 signaling pathway

AIM: To investigate the protective effects of glucagan-like peptide-1 (GLP-1) on cardiac microvascular injury in diabetic rats and the underlying mechanism. METHODS: Diabetic rats were induced by intraperitoneal injection of streptozocin, and then randomized to 3 months of vehicle or exenatide (a GLP-1 analogue) treatment. Before and after the treatment, body weight, blood glucose and blood pressure were measured. Cardiac microvascular permeability was detected by transmission electron microscopy. Cardiac microvascular endothelial cells (CMECs) were isolated and cultured in normal glucose (5.5 mmol/L), high glucose (25 mmol/L), and high glucose plus GLP-1 (10^-8 mol/L). The production of reactive oxygen species (ROS) was examined by superoxide assay kit and dihydroethidium staining. The protein expression of GLP-1 receptor (GLP-1R), Kelch-like epichlorohydrin-associated protein 1 (Keap1), nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was determined by Western blot. RESULTS: Exenatide treatment for 3 months improved the cardiac microvascular permeability in the diabetic rats. The GLP-1R was expressed in CMECs. GLP-1 inhibited high glucose-induced ROS production (P<0.05). Compared with high glucose group, the protein expression of Keap1 was decreased, and Nrf2 and HO-1 were increased significantly (P<0.05). CONCLUSION: GLP-1 inhibits oxidative stress in high glucose-induced CMECs, and improves the cardiac microvascular permeability in diabetic rats. The protective effects of GLP-1 may be related to Keap1-Nrf2 signaling pathway.     

Role of heme oxygenase-1 in the ischemic preconditioning of isolated rat heart

AIM: To investigate the influence of ischemic preconditioning on heart function, the activities of lactate dehydrogenase (LDH), malondialdehyde (MDA), and heme oxygenase-1 (HO-1) after ischemia/reperfusion in isolated rat heart. METHODS: The model of Langendorff was used in isolated rat heart perfusion. Ischemic preconditioning protocol: stopping perfusion for 5 minutes and reperfusion for 5 minutes, repeating three times. Ischemia protocol: stopping perfusion for 40 minutes and reperfusion for 20 minutes. Indexes of heart function were recorded in control M8, ischemia and reperfusion group (IR), and ischemic preconditioning group (IPC). The content of LDH of coronary effluent was measured. Moreover, the content of MDA and activity of HO-1 in myocardium were also measured. RESULTS: The recovery percentage of heart function in IPC group was significantly higher than that in IR group (P<0.01) and the activity of heme oxygenase-1 also increased significantly (P<0.05). CONCLUSION: The contents of LDH and MDA significantly decreased in IPC group compared with IR group. The increase in heme oxygenase-1 activity might be involved in the protective effect of ischemic preconditioning on ischemic/reperfused rat heart.     

Up-regulation of HO-1 protects ADSCs under serum-free and hypoxic conditions

AIM:To investigate the protective effects of endogenous heme oxygenase 1 (HO-1) induced by cobalt protoporphyrin (Copp, a HO-1 inducer) on adipose tissue-derived stromal cells (ADSCs) under the condition of serum-free and hypoxia. METHODS:The ADSCs were isolated from SD rat and cultured. The cell apoptotic rate was detected by DAPI staining. The protein expression of HO-1, NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC) and cleaved caspase-1 in ADSCs was messured by Western blotting. IL-1β level in supernatant was determined by ELISA. The level of intracellular reactive oxygen species (ROS) was detected using DCFH-DA. RESULTS:The up-regulation of HO -1 was induced by CoPP in a dose dependent manner and was most significant at 20 μmol/L. The increased expression of HO-1 induced by CoPP significantly reduced the apoptotic rate of ADSCs, intracellular ROS level and IL-1β secretion, and inhibited the overexpression of NLRP3, ASC and cleaved caspase-1 under serum and oxygen deprivation. These protective effects were reversed by zinc protoporphyrin (ZnPP, an HO-1 inhibitor) given simultaneously. CONCLUSION: The up-regulation of HO -1 expression induced by CoPP plays protective effect on ADSCs under the condition of serum and oxygen deprivation via inhibiting the activation of NLRP3 inflammasome and reducing IL-1β secretion.