Bilirubin decreases NOS2 expression via inhibition of NAD(P)H oxidase: implications for protection against endotoxic shock in rats.

We investigated a possible beneficial role for bilirubin, one of the products of heme degradation by the cytoprotective enzyme heme oxygenase-1 in counteracting Escherichia coli endotoxin-mediated toxicity. Homozygous jaundice Gunn rats, which display high plasma bilirubin levels due to deficiency of glucuronyl transferase activity, and Sprague-Dawley rats subjected to sustained exogenous bilirubin administration were more resistant to endotoxin (LPS)-induced hypotension and death compared with nonhyperbilirubinemic rats. LPS-stimulated production of nitric oxide (NO) was significantly decreased in hyperbilirubinemic rats compared with normal animals; this effect was associated with reduction of inducible NO synthase (NOS2) expression in renal, myocardial, and aortic tissues. Furthermore, NOS2 protein expression and activity were reduced in murine macrophages stimulated with LPS and preincubated with bilirubin at concentrations similar to that found in the serum of hyperbilirubinemic animals. This effect was secondary to inhibition of NAD(P)H oxidase since 1) inhibition of NAD(P)H oxidase attenuated NOS2 induction by LPS, 2) bilirubin decreased NAD(P)H oxidase activity in vivo and in vitro, and 3) down-regulation of NOS2 by bilirubin was reversed by addition of NAD(P)H. These findings indicate that bilirubin can act as an effective agent to reduce mortality and counteract hypotension elicited by endotoxin through mechanisms involving a decreased NOS2 induction secondary to inhibition of NAD(P)H oxidase

Cigarette smoke promotes dendritic cell accumulation in COPD; a Lung Tissue Research Consortium study

<p>Abstract</p> <p>Background</p> <p>Abnormal immune responses are believed to be highly relevant in the pathogenesis of chronic obstructive pulmonary disease (COPD). Dendritic cells provide a critical checkpoint for immunity by their capacity to both induce and suppress immunity. Although evident that cigarette smoke, the primary cause of COPD, significantly influences dendritic cell functions, little is known about the roles of dendritic cells in the pathogenesis of COPD.</p> <p>Methods</p> <p>The extent of dendritic cell infiltration in COPD tissue specimens was determined using immunohistochemical localization of CD83+ cells (marker of matured myeloid dendritic cells), and CD1a+ cells (Langerhans cells). The extent of tissue infiltration with Langerhans cells was also determined by the relative expression of the CD207 gene in COPD <it>versus </it>control tissues. To determine mechanisms by which dendritic cells accumulate in COPD, complimentary studies were conducted using monocyte-derived human dendritic cells exposed to cigarette smoke extract (CSE), and dendritic cells extracted from mice chronically exposed to cigarette smoke.</p> <p>Results</p> <p>In human COPD lung tissue, we detected a significant increase in the total number of CD83+ cells, and significantly higher amounts of CD207 mRNA when compared with control tissue. Human monocyte-derived dendritic cells exposed to CSE (0.1-2%) exhibited enhanced survival <it>in vitro </it>when compared with control dendritic cells. Murine dendritic cells extracted from mice exposed to cigarette smoke for 4 weeks, also demonstrated enhanced survival compared to dendritic cells extracted from control mice. Acute exposure of human dendritic cells to CSE induced the cellular pro-survival proteins heme-oxygenase-1 (HO-1), and B cell lymphoma leukemia-x(L) (Bcl-xL), predominantly through oxidative stress. Although activated human dendritic cells conditioned with CSE expressed diminished migratory CCR7 expression, their migration towards the CCR7 ligand CCL21 was not impaired.</p> <p>Conclusions</p> <p>These data indicate that COPD is associated with increased numbers of cells bearing markers associated with Langerhans cells and mature dendritic cells, and that cigarette smoke promotes survival signals and augments survival of dendritic cells. Although CSE suppressed dendritic cell CCR7 expression, migration towards a CCR7 ligand was not diminished, suggesting that reduced CCR7-dependent migration is unlikely to be an important mechanism for dendritic cell retention in the lungs of smokers with COPD.</p

Aldose Reductase Inhibition Prevents Metaplasia of Airway Epithelial Cells

BACKGROUND: Goblet cell metaplasia that causes mucus hypersecretion and obstruction in the airway lumen could be life threatening in asthma and chronic obstructive pulmonary disease patients. Inflammatory cytokines such as IL-13 mediate the transformation of airway ciliary epithelial cells to mucin-secreting goblet cells in acute as well as chronic airway inflammatory diseases. However, no effective and specific pharmacologic treatment is currently available. Here, we investigated the mechanisms by which aldose reductase (AR) regulates the mucus cell metaplasia in vitro and in vivo. METHODOLOGY/FINDINGS: Metaplasia in primary human small airway epithelial cells (SAEC) was induced by a Th2 cytokine, IL-13, without or with AR inhibitor, fidarestat. After 48 h of incubation with IL-13 a large number of SAEC were transformed into goblet cells as determined by periodic acid-schiff (PAS)-staining and immunohistochemistry using antibodies against Mucin5AC. Further, IL-13 significantly increased the expression of Mucin5AC at mRNA and protein levels. These changes were significantly prevented by treatment of the SAEC with AR inhibitor. AR inhibition also decreased IL-13-induced expression of Muc5AC, Muc5B, and SPDEF, and phosphorylation of JAK-1, ERK1/2 and STAT-6. In a mouse model of ragweed pollen extract (RWE)-induced allergic asthma treatment with fidarestat prevented the expression of IL-13, phosphorylation of STAT-6 and transformation of epithelial cells to goblet cells in the lung. Additionally, while the AR-null mice were resistant, wild-type mice showed goblet cell metaplasia after challenge with RWE. CONCLUSIONS: The results show that exposure of SAEC to IL-13 caused goblet cell metaplasia, which was significantly prevented by AR inhibition. Administration of fidarestat to mice prevented RWE-induced goblet cell metaplasia and AR null mice were largely resistant to allergen induced changes in the lung. Thus our results indicate that AR inhibitors such as fidarestat could be developed as therapeutic agents to prevent goblet cell metaplasia in asthma and related pathologies

Heme Oxygenase-1 Accelerates Cutaneous Wound Healing in Mice

Heme oxygenase-1 (HO-1), a cytoprotective, pro-angiogenic and anti-inflammatory enzyme, is strongly induced in injured tissues. Our aim was to clarify its role in cutaneous wound healing. In wild type mice, maximal expression of HO-1 in the skin was observed on the 2nd and 3rd days after wounding. Inhibition of HO-1 by tin protoporphyrin-IX resulted in retardation of wound closure. Healing was also delayed in HO-1 deficient mice, where lack of HO-1 could lead to complete suppression of reepithelialization and to formation of extensive skin lesions, accompanied by impaired neovascularization. Experiments performed in transgenic mice bearing HO-1 under control of keratin 14 promoter showed that increased level of HO-1 in keratinocytes is enough to improve the neovascularization and hasten the closure of wounds. Importantly, induction of HO-1 in wounded skin was relatively weak and delayed in diabetic (db/db) mice, in which also angiogenesis and wound closure were impaired. In such animals local delivery of HO-1 transgene using adenoviral vectors accelerated the wound healing and increased the vascularization. In summary, induction of HO-1 is necessary for efficient wound closure and neovascularization. Impaired wound healing in diabetic mice may be associated with delayed HO-1 upregulation and can be improved by HO-1 gene transfer

Physiologie et physiopathologie de l hème oxygénase 1 (implication dans la modulation de la contractilité et prolifération du muscle lisse bronchique et de la sécrétion de mucus dans les maladies obstructives bronchiques)

L asthme et la bronchopneumopathie chronique obstructive (BPCO) sont des maladies inflammatoires chroniques pulmonaires très fréquentes. Malgré les traitements actuellement disponibles, ces maladies sont responsables d une morbidité et mortalité en augmentation constante. Les mécanismes de ces maladies ne sont pas clairement identifiés. Des études récentes montrent de plus en plus un rôle des radicaux libres oxygénés (RLO) dans la physiopathologie des ces maladies, notamment à travers leur rôle dans des anomalies fonctionnelles du muscle lisse et de la sécrétion de mucus bronchiques. L'hème oxygénase (HO), enzyme responsable de la dégradation de l'hème, produisant du fer, de la bilirubine et du monoxyde de carbone (CO), a des propriétés antioxydantes et anti-inflammatoires puissantes. Notre objectif a été d'étudier le rôle de l'HO dans les anomalies de la contractilité et la prolifération de la cellule musculaire lisse (CML) et de la sécrétion de mucus bronchiques dans l asthme et la BPCO. Nos résultats montrent que l'HO-1 module la signalisation redox dans les CML bronchiques, ce qui se traduit par une diminution de la réponse contractile et de la prolifération musculaires in vitro et par des effets protecteurs vis à vis de l hyperréactivité bronchique in vivo, dans un modèle animal d'asthme allergique. L HO-1 module également la sécrétion de mucus via la diminution de la production des RLO in vivo dans un modèle animal de BPCO induite par l exposition à la fumée de cigarette. Le(s) mécanisme(s) de la diminution de la production de RLO secondaire à l'activation de la voie de l'HO est multiple : effet antioxydant propre de la bilirubine et/ou diminution de l expression et de l activité de la Dual oxydase1 (DUOX1), un homologue de gp91phox (l unité principale de NADPH oxydase du phagocyte). Ces résultats suggèrent que l induction de la voie de l HO pourrait constituer une nouvelle approche thérapeutique dans l asthme et la BPCO.In spite of the effective treatments, asthma and chronic obstructive pulmonary disease (COPD), remain responsible for important rate of morbidity and mortality in the life. The mechanisms of these chronic inflammatory diseases are not clearly identified. More and more recent studies show the role of the reactive oxygen species (ROS) in their pathophysiological characteristics, notably certain functional abnormalities of the airway smooth muscle (ASM) and the hypersecretion of mucus. Heme oxygenase (HO), the enzyme responsible for heme degradation to produce iron, bilirubin and carbon monoxide (CO), has powerful antioxidizing and antiinflammatory properties. Our objective in this study was to analyse the role of HO in ASM contractility and proliferation, airway inflammation and mucus hypersecretion in asthma and COPD. We showed that HO-1 modulated redox signalisation pathways in ASM, which is translated by a decrease in muscle contractility and proliferation in vitro and providing protective effects in vivo in an animal model of allergic asthma. HO-1 also modulated mucus secretion by decreasing ROS in vivo in an animal model of cigarette smoke-induced COPD. The mechanism of HO-1-induced decrease in ROS production is multiple: direct antioxidant effect of bilirubin, downregulation and inactivation of Dual oxidase1 (DUOX1), a gp91phox homolog (the main subunit of NAD(P)H oxidase).PARIS12-Bib. électronique (940280011) / SudocSudocFranceF

ET_Breceptor polymorphism is associated with airway obstruction

Abstract Background Endothelin-1 (EDN1) has been involved in the development of airway obstruction and inflammation in asthma. Several polymorphisms have been identified among the genes encoding for preproET1, an inactive precursor of ET-1, and for ETA (EDNRA) and ETB (EDNRB), the two receptors for EDN1. In the present work, we hypothesised that molecular variation in these genes could be a major determinant of the degree of bronchial obstruction. The purpose of this study was to investigate whether the genetic polymorphisms of preproET-1, EDNRA and EDNRB genes were associated with the degree of airway obstruction, assessed by FEV1. Methods Polymorphisms of preproET-1, EDNRA and EDNRB were first studied in a population of adult asthmatic patients. Results were confirmed in a large population of adults from the general population from the ECRHS II study. Results In our population of adult asthmatic patients, the EDNRB-30G>A (Leu277Leu) polymorphism (GG genotype) is strongly associated with a low FEV1 and with a higher percentage of patients with FEV1 T (His323His) or preproET-1-595G>T (Lys198Asp) polymorphism. In the adult population from the ECRHS II, we found a similar association between GG genotype and a low FEV1 or a higher percentage of subjects with FEV1 Conclusion the EDNRB-30G>A polymorphism could be a determinant of airway obstruction in humans with predisposing factors such as tobacco smoke exposure or asthma.</p