Hypercapnia downregulates hypoxia-induced lysyl oxidase expression in pulmonary artery smooth muscle cells via inhibiting transforming growth factor ß1 signalling.

Hypoxic pulmonary arterial hypertension is characterized by elevated pulmonary vascular resistance and remodelling. Transforming growth factor-ß1 (TGF-ß1 ) is the master regulator in cellular response to hypoxia which can directly target lysyl oxidase (LOX). This study aimed to determine whether hypercapnia attenuates hypoxic pulmonary hypertension via regulating TGF-ß1 and LOX signalling. We found that exposure to hypercapnia ameliorated the increase in mean pulmonary artery pressure (mPAP) and ratio of right ventricle to left ventricle plus septum (RV/(LV + S)) induced by hypoxia but had no effect on mPAP and RV/(LV + S) in normoxia-exposed control. In addition, exposure to hypoxia upregulated the mRNA and protein levels of LOX and TGF-ß1 in rat PASMCs both in vivo and in vitro, but these effects were abrogated by concurrent exposure to hypercapnia. The downregulation of LOX in rat PASMCs induced by hypercapnia was reversed by the administration with TGF-ß1 , while TGF-ß1 knockdown repressed the upregulation of LOX in hypoxia-exposed rat PASMCs. In conclusion, hypoxia upregulates LOX and TGF-ß1 expression in PASMCs and contributes to pulmonary hypertension. Hypercapnia downregulates hypoxia-induced LOX expression and alleviates hypoxia-associated pulmonary hypertension via inhibiting TGF-ß1 signalling. SIGNIFICANCE OF THE STUDY: Hypoxia-induced upregulation of TGF-ß1 , PDGF, and HIF-1α plays a pivotal role in PAH, but molecular mechanism of how hypoxia regulates LOX expression is not clear. In the present study, we showed that mRNA and protein expression levels of LOX were substantially increased when TGF-ß1 was induced by hypoxia, and the effects were reversed by TGF-ß1 knockdown. Our study indicates that TGF-ß1 is implicated in the regulation of LOX.

Neuroprotective effects of N-acetyl cysteine on primary hippocampus neurons against hydrogen peroxide-induced injury are mediated via inhibition of mitogen-activated protein kinases signal transduction and antioxidative action.

N-acetyl cysteine (NAC) has been extensively reported to exert neuroprotective effects on the central nervous system. Oxidative stress may contribute to the underlying mechanisms causing Alzheimer's disease (AD). The effect of NAC against oxidative stress injury was investigated in a cellular model of AD in the present study and the underlying mechanisms were revealed. The neuroprotective action of NAC (1, 10, 100 and 1,000 µmol/l) on a cellular model of AD [hydrogen peroxide (H2O2)­induced (3, 30 and 300 µmol/l) toxicity in primary rat hippocampus neurons] demonstrated the underlying mechanisms. Cytotoxicity was measured using the MTT assay, and light microscopy and the dichloro-dihydro-fluorescein diacetate method were used to detect the reactive oxygen species (ROS) levels. Furthermore, the levels of mitogen-activated protein kinases (MAPKs) signal transduction and tau protein phosphorylation were measured via western blotting. NAC (100 µmol/l) protected hippocampus neurons against H2O2­mediated toxicity, as evidenced by enhanced cell viability. Using MTT assay and light microscopy for the observation of cell death, NAC ameliorated cell viability, which was induced by H2O2 injury (P<0.05). NAC was found to mitigate the excessive production of ROS (P<0.05). Another mechanism involved in the neuroprotective action of NAC may be its ability to inhibit MAPK signal transduction following H2O2 exposure. In addition, NAC may protect cells against H2O2­induced toxicity by attenuating increased tau phosphorylation. Thus, the protective ability of NAC is hypothesized to result from inhibition of oxidative stress and downregulation of MAPK signal transduction and tau phosphorylation.

Suppression of Phosphatidylinositol 3-Kinase/Akt Signaling Attenuates Hypoxia-Induced Pulmonary Hypertension Through the Downregulation of Lysyl Oxidase.

Lysyl oxidase (LOX) is a copper-dependent enzyme that catalyzes covalent cross-linking of collagen. In response to hypoxia, phosphatidylinositol 3-kinase (PI3K) pathway is activated and contributes to pulmonary arterial hypertension (PAH). However, potential role of LOX in hypoxia-induced PAH is poorly understood. In this study, we explored the mechanism responsible for the development of hypoxia-induced PAH. Potent inhibitors of PI3K/Akt and LOX, wortmannin and ß-aminopropionitrile (ß-APN), were administrated in rat model of hypoxia-induced PAH. The cross-linking of collagen was assessed by the determination of hydroxyproline. LOX, LOXL-1, LOXL-2, LOXL-3, LOXL-4, Akt, and phospho-Akt expression was detected by real-time polymerase chain reaction and western blot analysis. We observed that collagen cross-linking and LOX activity were elevated in hypoxia-exposed rat lung tissue, but these effects were reversed by ß-APN and wortmannin. In addition, exposure to hypoxia enhanced mRNA and protein expression and activity of LOX and LOXL-1 in a PI3K/Akt-dependent manner and induced the development of PAH. After the administration of wortmannin, the upregulation of LOX and cross-linking of collagen were significantly reversed in hypoxia-exposed rat pulmonary artery tissue. Taken together, the present study demonstrated that the upregulation of LOX expression and collagen cross-linking is PI3K/Akt dependent in rat with hypoxia-induced PAH. Suppression of PI3K/Akt pathway may alleviate hypoxia-induced PAH through the downregulation of LOX.

Massive cryptogenic hemoptysis undergoing pulmonary resection: clinical and pathological characteristics and management.

Massive cryptogenic hemoptysis is a common presenting symptom and cause of hospitalization for respiratory diseases, and represents a challenging condition in the clinical. This study aimed to analyze the clinical and pathologic data and management of patients with massive cryptogenic hemoptysis. We retrospectively reviewed 12 patients with massive cryptogenic hemotysis in our hospital between January 2003 and December 2012. Bronchoscopy showed submucosal vascular abnormalities in 4 patients. Of 6 patients managed with conservative measures, bleeding was completely controlled in 2 patients. Of 10 hemoptysis patients, three were controlled by bronchial arterial embolization, and seven by surgery. Pathological examination showed a superficial dysplastic, tortuous and dilated bronchial artery under the bronchial epithelium in 4 patients, and bronchiole dilation in 2 patients, indicating Dieulafoy's disease of the bronchus and bronchiectasis. No malignance developed within the follow-up. In conclusion, Dieulafoy's disease of the bronchus and bronchiectasis should be suspected in patients with massive cryptogenic hemoptysis. BAE and surgical treatment should be considered in case that massive hemoptysis could not be controlled by conservative management.

Roxithromycin suppresses airway remodeling and modulates the expression of caveolin-1 and phospho-p42/p44MAPK in asthmatic rats.

Roxithromycin (RXM) expresses anti-asthmatic effects that are separate from its antibiotic activity, but its effects on airway remodeling are still unknown. Here, we evaluated the effects of RXM on airway remodeling and the expression of caveolin-1 and phospho-p42/p44mitogen-activated protein kinase (phospho-p42/p44MAPK) in chronic asthmatic rats. The chronic asthma was induced by ovalbumin/Al(OH)3 sensitization and ovalbumin challenge, RXM (30mg/kg) or dexamethasone (0.5mg/kg) was given before airway challenge initiation. We measured the thickness of bronchial wall and bronchial smooth muscle cell layer to indicate airway remodeling, and caveolin-1 and phospho-p42/p44MAPK expression in lung tissue and airway smooth muscle were detected by immunohistochemistry and western blot analysis, respectively. The results demonstrated that RXM treatment decreased the thickness of bronchial wall and bronchial smooth muscle cell layer, and also downregulated the phospho-p42/p44MAPK expression and upregulated the caveolin-1 expression. The above effects of RXM were similar to dexamethasone. Our results suggested that pretreatment with RXM could suppress airway remodeling and regulate the expression of caveolin-1 and phospho-p42/p44MAPK in chronic asthmatic rats.

Impaired iNOS-sGC-cGMP signalling contributes to chronic hypoxic and hypercapnic pulmonary hypertension in rat.

Nitric oxide (NO) is an important vascular modulator in the development of pulmonary hypertension. NO exerts its regulatory effect mainly by activating soluble guanylate cyclase (sGC) to synthesize cyclic guanosine monophosphate (cGMP). Exposure to hypoxia causes pulmonary hypertension. But in lung disease, hypoxia is commonly accompanied by hypercapnia. The aim of this study was to examine the changes of sGC enzyme activity and cGMP content in lung tissue, as well as the expression of inducible nitric oxide synthase (iNOS) and sGC in rat pulmonary artery after exposure to hypoxia and hypercapnia, and assess the role of iNOS-sGC-cGMP signal pathway in the development of hypoxic and hypercapnic pulmonary hypertension. Male Sprague-Dawley rats were exposed to hypoxia and hypercapnia for 4 weeks to establish model of chronic pulmonary hypertension. Weight-matched rats exposed to normoxia served as control. After exposure to hypoxia and hypercapnia, mean pulmonary artery pressure, the ratio of right ventricle/left ventricle+septum, and the ratio of right ventricle/body weight were significantly increased. iNOS mRNA and protein levels were significantly increased, but sGC α(1) mRNA and protein levels were significantly decreased in small pulmonary arteries of hypoxic and hypercapnic exposed rat. In addition, basal and stimulated sGC enzyme activity and cGMP content in lung tissue were significantly lower after exposure to hypoxia and hypercapnia. These results demonstrate that hypoxia and hypercapnia lead to the upregulation of iNOS expression, downregulation of sGC expression and activity, which then contribute to the development of pulmonary hypertension.

[Effects of intervene on occupational health knowledge, attitude and practice of people with occupational disease risk in private enterprises].

OBJECTIVE: To evaluate the effects of health promotion on occupational health based on the changes in knowledge, attitude and practice (KAP) before and after intervention of people with occupational disease risk in private enterprises. METHODS: 202 people with occupational disease risk in private leather enterprises of Wenzhou were surveyed, who were rechecked with the same questionnaire after three months intervention. RESULTS: The knowledge, attitude and practice scores (9.34 ± 2.57, 7.79 ± 2.58 and 7.24 ± 2.50, respectively) of post-intervention group were significantly increased more than those of pre-intervention (8.06 ± 2.71, 7.63 ± 2.67, 7.11 ± 2.60, respectively) (P < 0.01, P < 0.05). The net increases of knowledge, attitude and practice scores were significantly different with different length of service, educational level, registered residence and training experience (P < 0.05, P < 0.01). CONCLUSIONS: Health promotion could increase knowledge, attitude and practice levels; The effect of intervention on people with short length of service, low educational level, coming from country and had not attended training is significant.

[Study on soluble guanylate cyclase in pulmonary hypertension rat model].

OBJECTIVE: To investigate the mRNA and protein expressions of soluble guanylate cyclase (sGC) and its enzyme activity in pulmonary hypertension rat model which was reproduced by hypoxia and hypercapnia. METHODS: Male Sprague-Dawley rats were randomly divided into hypoxic and hypercapnic group (HH group) and control group (C group). The protein expressions of sGC alpha(1) and sGC beta(1) subunits in medial and small pulmonary arteries was measured by immunohistochemistry method with a polycolonal antibody. The mRNA expression of sGC alpha(1) subunit of lung tissue was detected by in situ hybridization using sGC oligonuclear probe. Basal sGC enzyme activity and sodium nitroprusside (SNP)-stimulated sGC activity in lung homogenates were assayed with enzyme kinetic analysis. RESULTS: The mean pulmonary artery pressure (mPAP), the ratio of right ventricle/left ventricle + septum [RV/(LV + S)] and the ratio of right ventricle/body weight (RV/BW) were significantly higher in HH group than those in C group. The protein expressions of sGC alpha(1) and sGC beta(1) subunits and mRNA expressions of sGC alpha(1) subunit were significantly decreased in the small and medium pulmonary arteries in HH group as compared with those in C group (P < 0.01). Basal sGC enzyme activity in HH group (32.03 +/- 7.17 pmol cGMP synthesized.mg protein(-1).min(-1)) was significantly lower than that in C group (114.76 +/- 18.37 pmol cGMP synthesized.mg protein(-1).min(-1), P < 0.01). The SNP significantly increased the sGC enzyme activity but the SNP-stimulated sGC enzyme activity of lung homogenates in HH group was significantly lower than that in C group (P < 0.01). CONCLUSIONS: The mRNA and protein expressions of sGC subunits and their enzyme activities in lung tissue of pulmonary hypertension rat model were reduced.