4843

NOS2

HEP-NOS|INOS|NOS|NOS2A;nitric oxide synthase 2, inducible;NOS2;nitric oxide synthase 2, inducible

NOS type II|NOS, type II|hepatocyte NOS|inducible NO synthase|inducible NOS|nitric oxide synthase 2A (inducible, hepatocytes)|nitric oxide synthase, inducible|nitric oxide synthase, macrophage|peptidyl-cysteine S-nitrosylase NOS2

17q11.2-q12

protein-coding

Count: Nos2; 24599

Pathogenesis of hypoxic pulmonary hypertension is initiated by oxidative injury to the pulmonary vascular wall. Because nitric oxide (NO) can contribute to oxidative stress and because the inducible isoform of NO synthase (iNOS) is often upregulated in association with tissue injury, we hypothesized that iNOS-derived NO participates in the pulmonary vascular wall injury at the onset of hypoxic pulmonary hypertension. An effective and selective dose of an iNOS inhibitor, L-N6-(1-iminoethyl)lysine (L-NIL), for chronic peroral treatment was first determined (8 mg/l in drinking water) by measuring exhaled NO concentration and systemic arterial pressure after LPS injection under ketamine+xylazine anesthesia. A separate batch of rats was then exposed to hypoxia (10% O2) and given L-NIL or a nonselective inhibitor of all NO synthases, N(G)-nitro-L-arginine methyl ester (L-NAME, 500 mg/l), in drinking water. Both inhibitors, applied just before and during 1-wk hypoxia, equally reduced pulmonary arterial pressure (PAP) measured under ketamine+xylazine anesthesia. If hypoxia continued for 2 more wk after L-NIL treatment was discontinued, PAP was still lower than in untreated hypoxic controls. Immunostaining of lung vessels showed negligible iNOS presence in control rats, striking iNOS expression after 4 days of hypoxia, and return of iNOS immunostaining toward normally low levels after 20 days of hypoxia. Lung NO production, measured as NO concentration in exhaled air, was markedly elevated as early as on the first day of hypoxia. We conclude that transient iNOS induction in the pulmonary vascular wall at the beginning of chronic hypoxia participates in the pathogenesis of pulmonary hypertension.

The molecular basis of the pathogenesis of pulmonary hypertension (PH) associated with congenital diaphragmatic hernia (CDH) is poorly understood. Variation in responses to therapeutic strategies such as nitric oxide (NO) inhalation and extracorporeal membrane oxygenation (ECMO) in patients with CDH remains a major problem in pediatric critical care. We investigated the expression pattern of NO-generating enzyme nitric-oxide synthase (NOS) (both endothelial [eNOS] and inducible [iNOS] isoforms) in the lungs of CDH patients with PH and evaluated the influence of ECMO on the expression levels of these genes in an attempt to understand the underlying molecular mechanisms. Lung autopsy specimens from 23 cases of CDH not treated by ECMO and 10 ECMO-treated CDH cases were studied and compared with 11 age-matched controls. expression of iNOS and eNOS was assessed by immunohistochemistry and video-image analysis. expression of iNOS in the endothelium of small pulmonary arteries (external diameter < or =200 Mum) was significantly lower in CDH cases that had not received ECMO treatment (p = 0.04). ECMO-treated CDH cases did not differ from controls in iNOS expression. Alveolar macrophages (CD68+ cells), of which the number also was increased, showed significantly enhanced staining for iNOS in CDH cases (p = 0.03) compared with controls. The observed decrease in pulmonary expression of iNOS in patients with CDH suggests a potential role in the pathogenesis of pulmonary hypertension in newborns with CDH. ECMO treatment was correlated with induction of this enzyme, which may result in NO-mediated vasodilatation and thereby transiently reduce the pulmonary hypertension in CDH.

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis. One of several complications of SSc, pulmonary arterial hypertension (PAH) can be refractory to treatment, both novel and established. In the present study we investigated the ratio of circulating nitric oxide to endothelin-1 in patients with both SSc and PAH, and determined whether polymorphisms in NOS2 (the nitric oxide synthase 2 gene) are associated with susceptibility to PAH. Endothelin-1 in plasma and nitric oxide metabolites (nitrate and nitrite) in serum were measured. The nitric oxide/endothelin-1 ratio was significantly lower in patients with both SSc and PAH than in patients with SSc only or in healthy control individuals. We confirmed the presence of two single nucleotide polymorphisms at positions -1,026 and -277 and a pentanucleotide repeat (CCTTT) at -2.5 kilobases. There were significant differences in single nucleotide polymorphisms between patients with SSc who had PAH and those who did not, and between patients with both SSc and PAH and healthy control individuals. The CCTTT repeat was significantly shorter in patients with both SSc and PAH than in patients with SSc only or in healthy control individuals. Transcriptional activity were analyzed using the luciferase reporter assay. The transcriptional activity of NOS2 was much greater in fibroblasts transfected by a vector with a long allele of the CCTTT repeat than in those transfected by a vector with a short allele. Polymorphisms in the NOS2 gene are associated with transcriptional activity of the NOS2 gene and with susceptibility to SSc-related PAH.

RATIONALE: Nitric oxide is an important regulator of vascular tone in the pulmonary circulation. Surgical correction of congenital heart disease limits pulmonary hypertension to a brief period. OBJECTIVES: The study has measured expression of endothelial (eNOS), inducible (iNOS), and neuronal nitric oxide synthase (nNOS) in the lungs from biopsies of infants with pulmonary hypertension secondary to cardiac abnormalities (n = 26), compared to a control group who did not have pulmonary or cardiac disease (n = 8). METHODS: eNOS, iNOS and nNOS were identified by immunohistochemistry and quantified in specific cell types. MEASUREMENTS AND MAIN RESULTS: Significant increases of eNOS and iNOS staining were found in pulmonary vascular endothelial cells of patients with congenital heart disease compared to control infants. These changes were confined to endothelial cells and not present in other cell types. Patients who strongly expressed eNOS also had strong expression of iNOS. CONCLUSION: Upregulation of eNOS and iNOS occurs at an early stage of pulmonary hypertension, and may be a compensatory mechanism limiting the rise in pulmonary artery pressure.

Nitric oxide is involved in development and postnatal adaptation of the pulmonary circulation. This study aimed to determine whether genetic deletion of nitric oxide synthase (NOS) would lead to maldevelopment of the pulmonary arteries in fetal life, compromise adaptation to extrauterine life, and be associated with a pulmonary hypertensive phenotype in adult life and if any abnormalities were detected, were they sex dependent. Morphometric analyses were made on lung tissue from male and female fetal, newborn, 14-day-old, and adult endothelial NOS-deficient (eNOS-/-) or inducible NOS-deficient (iNOS-/-) and wild-type mice. Hemodynamic studies were carried out on adult mice with deletion of either eNOS or iNOS genes. We found that in eNOS-/- mice, lung development was normal in fetal, newborn, and adult lungs. Pulmonary arterial muscularity was greater than normal in both male and female eNOS-/- during fetal life and at birth, but the abnormality persisted only in male mice. Right ventricular hypertrophy was present in 14-day-old and adult male eNOS-/- but not in female mice. Adult male eNOS-/- mice had higher mean right ventricular and systemic pressures than female eNOS-/- mice (P < 0.05). Thus deletion of the eNOS gene was associated with structural evidence of pulmonary hypertension in both sexes during fetal life, but pulmonary hypertension persisted only in the male. In neither sex did iNOS or neuronal NOS appear to compensate for the eNOS deletion. Adult iNOS-/- mice did not have structural or hemodynamic evidence of pulmonary hypertension. Possible compensatory mechanisms are discussed.

OBJECTIVE: To investigate the dynamic expression of transforming growth factor beta(1)(TGF-beta(1)) and inducible nitric oxide synthase (iNOS) in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension (HPH). METHODS: Forty adult male Wistar rats were randomly divided into five groups: a control group (C group) and groups with hypoxia for 3, 7, 14 and 21 days (H(3), H(7), H(14), H(21) group), eight rats per group. Mean pulmonary arterial pressure (mPAP), vessel morphometry and right ventricle hypertrophy index (RVHI) were measured. Lungs were inflation fixed for in situ hybridization and immunohistochemistry. RESULTS: mPAP increased significantly in H(7) group [(18.41 +/- 0.37) mm Hg, 1 mm Hg = 0.133 kPa, P < 0.05], reaching its peak in H(14) group [(21.17 +/- 0.23) mm Hg], then remained at the high level. hypoxia induced pulmonary artery remodeling and right ventricle hypertrophy index became evident in H(14) group. expression of iNOS protein in control group (0.109 +/- 0.021) was weakly positive in pulmonary arterial tunica media, while the level of iNOS protein was markedly up-regulated in H(3) group (0.225 +/- 0.030, P < 0.01), reaching its peak in H(7) group (0.312 +/- 0.036), then remained at the high level. expression of iNOS mRNA in C group (0.112 +/- 0.030) was weakly positive in pulmonary arterial wall, while the level of iNOS mRNA was markedly up-regulated in H(3) group (0.245 +/- 0.036), reaching its peak in H(7) group (0.318 +/- 0.034, P < 0.01), then remained at the high level. expression of TGF-beta(1) protein in C group (0.042 +/- 0.012) was weakly positive, but the level of TGF-beta(1) protein was markedly up-regulated in H(3) group (0.198 +/- 0.031), reaching its peak in H(7) group (0.267 +/- 0.035, P < 0.01), and then tended to decline in H(14) and H(21) group. TGF-beta(1) mRNA staining was weakly positive in C group (0.145 +/- 0.018), H(3) group (0.163 +/- 0.021) and H(7) group (0.176 +/- 0.026), but began to increase significantly in H(14) group (0.385 +/- 0.028, P < 0.01), and then remained stable. TGF-beta(1) protein and mRNA were located predominantly in tunica adventitia and tunica media. Linear correlation analysis showed that TGF-beta(1) mRNA, iNOS mRNA and protein were positively correlated with mPAP, vessel morphometry and RVHI (r = 0.843 - 0.937, all P < 0.01). TGF-beta(1) protein (tunica adventitia) was negatively correlated with iNOS mRNA and protein (r = -0.856, -0.835, all P < 0.01). CONCLUSIONS: Interaction of TGF-beta(1) and iNOS plays a role in the pathogenesis of HPH in rats. iNOS can regulate the expression of TGF-beta(1) gene by NO. TGF-beta(1) can regulate the expression of iNOS gene by decreased stability and translation of iNOS mRNA and increased degradation of iNOS protein.

The molecular basis of the pathogenesis of pulmonary hypertension (PH) associated with congenital diaphragmatic hernia (CDH) is poorly understood. Variation in responses to therapeutic strategies such as nitric oxide (NO) inhalation and extracorporeal membrane oxygenation (ECMO) in patients with CDH remains a major problem in pediatric critical care. We investigated the expression pattern of NO-generating enzyme nitric-oxide synthase (NOS) (both endothelial [eNOS] and inducible [iNOS] isoforms) in the lungs of CDH patients with PH and evaluated the influence of ECMO on the expression levels of these genes in an attempt to understand the underlying molecular mechanisms. Lung autopsy specimens from 23 cases of CDH not treated by ECMO and 10 ECMO-treated CDH cases were studied and compared with 11 age-matched controls. expression of iNOS and eNOS was assessed by immunohistochemistry and video-image analysis. expression of iNOS in the endothelium of small pulmonary arteries (external diameter < or =200 Mum) was significantly lower in CDH cases that had not received ECMO treatment (p = 0.04). ECMO-treated CDH cases did not differ from controls in iNOS expression. Alveolar macrophages (CD68+ cells), of which the number also was increased, showed significantly enhanced staining for iNOS in CDH cases (p = 0.03) compared with controls. The observed decrease in pulmonary expression of iNOS in patients with CDH suggests a potential role in the pathogenesis of pulmonary hypertension in newborns with CDH. ECMO treatment was correlated with induction of this enzyme, which may result in NO-mediated vasodilatation and thereby transiently reduce the pulmonary hypertension in CDH.

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis. One of several complications of SSc, pulmonary arterial hypertension (PAH) can be refractory to treatment, both novel and established. In the present study we investigated the ratio of circulating nitric oxide to endothelin-1 in patients with both SSc and PAH, and determined whether polymorphisms in NOS2 (the nitric oxide synthase 2 gene) are associated with susceptibility to PAH. Endothelin-1 in plasma and nitric oxide metabolites (nitrate and nitrite) in serum were measured. The nitric oxide/endothelin-1 ratio was significantly lower in patients with both SSc and PAH than in patients with SSc only or in healthy control individuals. We confirmed the presence of two single nucleotide polymorphisms at positions -1,026 and -277 and a pentanucleotide repeat (CCTTT) at -2.5 kilobases. There were significant differences in single nucleotide polymorphisms between patients with SSc who had PAH and those who did not, and between patients with both SSc and PAH and healthy control individuals. The CCTTT repeat was significantly shorter in patients with both SSc and PAH than in patients with SSc only or in healthy control individuals. Transcriptional activity were analyzed using the luciferase reporter assay. The transcriptional activity of NOS2 was much greater in fibroblasts transfected by a vector with a long allele of the CCTTT repeat than in those transfected by a vector with a short allele. Polymorphisms in the NOS2 gene are associated with transcriptional activity of the NOS2 gene and with susceptibility to SSc-related PAH.

A recent study showed that long-term administration of the inducible nitric oxide synthase (iNOS) inhibitor L-NIL reduced the development of pulmonary hypertension. The purpose of the present study was to identify the effect of an another iNOS inhibitor, ONO-1714, on the development of pulmonary hypertensive vascular changes in chronic hypoxic pulmonary hypertension in rats. ONO-1714 was administered to rats exposed to hypobaric hypoxia (air at 380 mmHg) for 10 days. Muscularization of normally nonmuscular peripheral arteries and medial hypertrophy of normally muscular arteries were assessed by light microscopy. iNOS mRNA and protein levels of the lung were assessed in normal and hypoxic rats. Chronic hypoxia induced pulmonary hypertension, right ventricular hypertrophy, and hypertensive pulmonary vascular changes. Although an acute single injection of ONO-1714 induced a significant increase in mean pulmonary artery pressure in chronic hypoxic pulmonary hypertensive rats, the increase was slight and transient. There were no significant differences among rats with and without long-term administration of ONO-1714 in pulmonary artery pressure, right ventricular hypertrophy, medial wall thickness of muscular arteries, and the percentage of muscularized arteries at the alveolar wall and duct levels. Although there was a significantly increased expression of iNOS as assessed with the reverse-transcription polymerase chain reaction in rats that were exposed to 10 days of hypobaric hypoxia, we could not detect a significant level of iNOS protein by Western blotting. ONO-1714 does not have a therapeutic role in preventing the development of chronic hypoxic pulmonary hypertension.

1. Hypertensive mice expressing the human renin (REN) and angiotensinogen (AGT) genes are used as a model for human hypertension. 2. The aim of the present study was to investigate the cellular expression and distribution of inducible nitric oxide synthase (iNOS) using immunohistochemistry in lung, heart and kidney tissues from a model of human hypertension using male and female double-transgenic (h-Ang 204/1h-Ren6) mice and wild-type C57/BI6J mice as controls. 3. In the kidney, the pattern of iNOS expression in various renal microanatomical regions during hypertension was similar to that of age-matched controls, except in the medullary ascending limb (MAL). In hypertension, iNOS expression was downregulated in the MAL. No significant differences in iNOS expression were seen between control or hypertensive mice in various cardiac microanatomical locations. In the lungs of hypertensive mice, iNOS expression was upregulated in bronchial airway epithelium and bronchial and vascular smooth muscle cells, but downregulated in alveolar macrophages, alveolar septa and pulmonary vascular endothelial cells. expression of iNOS was similar between male and female mice in the kidney, heart and lungs. 4. In conclusion, iNOS regulation in hypertension is complex and depends on the cell type in which it is expressed and the localization of the cell type in the cardiorenal and pulmonary systems.

RATIONALE: Nitric oxide is an important regulator of vascular tone in the pulmonary circulation. Surgical correction of congenital heart disease limits pulmonary hypertension to a brief period. OBJECTIVES: The study has measured expression of endothelial (eNOS), inducible (iNOS), and neuronal nitric oxide synthase (nNOS) in the lungs from biopsies of infants with pulmonary hypertension secondary to cardiac abnormalities (n = 26), compared to a control group who did not have pulmonary or cardiac disease (n = 8). METHODS: eNOS, iNOS and nNOS were identified by immunohistochemistry and quantified in specific cell types. MEASUREMENTS AND MAIN RESULTS: Significant increases of eNOS and iNOS staining were found in pulmonary vascular endothelial cells of patients with congenital heart disease compared to control infants. These changes were confined to endothelial cells and not present in other cell types. Patients who strongly expressed eNOS also had strong expression of iNOS. CONCLUSION: Upregulation of eNOS and iNOS occurs at an early stage of pulmonary hypertension, and may be a compensatory mechanism limiting the rise in pulmonary artery pressure.

OBJECTIVE: To investigate the roles of hypoxia-inducible factor-1alpha (HIF-1alpha), endothelin-1 (ET-1) and inducible nitric oxide synthase (iNOS) in the pathogenesis of hypoxia-induced pulmonary hypertension (HPH) of the newborn. METHODS: Seventy-five term hospitalized neonates with HPH (mild 29 cases, moderate 25 cases, severe 21 cases) and 22 term hospitalized neonates without HPH (control group) were enrolled between June 2006 and November 2009. Serum levels of HIF-1alpha, iNOS and ET-1 were measured using ELASA 1, 3 and 7 days after birth. RESULTS: Serum concentrations of HIF-1alpha and ET-1 in the mild, moderate and severe HPH groups were significantly higher than those in the control group (P<0.01) 1 day after birth, and were related to the severity of HPH. The serum iNOS concentrations in the moderate and severe HPH groups were also significantly higher than those in the control group (P<0.01). By 3 days after birth, serum ET-1 concentration in the moderate HPH group and serum concentrations of HIF-1alpha, ET-1 and iNOS in the severe HPH group reminded significantly higher than those in the control group (P<0.05). At 7 days after birth, serum ET-1 concentration in the severe HPH group still remained higher than that in the control group (P<0.05). CONCLUSIONS: Serum levels of HIF-1alpha, ET-1 and iNOS increase in neonates with HPH, resulting in an imbalance of ET-1 and NO. This may be of importance in the pathogenesis of neonatal HPH.