Bleomycin Binding Sites on Alveolar Macrophages

Previous work has demonstrated that bleomycin can directly stimulate alveolar macrophage secretion of fibroblast growth factors and monocyte chemotactic factors. In this study, rat alveolar macrophages obtained by bronchoalveolar lavage were examined for the presence of bleomycin binding sites, which might mediate this response. The results indicated that alveolar macrophages have specific, saturable, and reversible binding sites. Both high‐ and low‐affinity binding sites were found; each macrophage possessed 6.7 × 104 high‐affinity sites, with a Kd, of 528 nM, and 2.2 × 106 low‐affinity sites, with a Kd of 65 μM. The Kd of the high‐affinity sites corresponds closely to the ED50 obtained from dose‐response curves of the bleomycin‐stimulated secretion of both fibroblast growth and monocyte chemotactic factors, suggesting that bleomycin stimulation of alveolar macrophage function responses may be mediated by bleomycin interaction with these sites.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141017/1/jlb0519.pd

A role for C‐C chemokines in fibrotic lung disease

Pulmonary fibrosis is the end point of a chronic inflammatory process characterized by leukocyte recruitment and activation, fibroblast proliferation, and increased extracellular matrix production. Previous studies of models of pulmonary fibrosis have investigated the role of cytokines in the evolution of the fibrotic response. The involvement of tumor necrosis factor and interleukin‐1 in bleomycin‐induced lung injury, a model of idiopathic pulmonary fibrosis, has been well established, suggesting that cytokines mediate the initiation and maintenance of chronic inflammatory lesions. However, the aforementioned cytokines alone cannot account for the recruitment and activation of specific leukocyte populations found in the bleomycin model. Recently, a family of novel proinflammatory cytokines (chemokines) was cloned and characterized, yielding many putative mediators of leukocyte functions. Macrophage inflammatory protein‐1α (MIP‐1α) and monocyte chemoattractant protein‐1 (MCP‐1) belong to the C‐C chemotactic cytokine family, a group of low‐molecular‐weight peptides. These molecules modulate chemotaxis, proliferation, and cytokine expression in leukocyte subsets. Our group has investigated the roles of MCP‐1 and MIP‐1α in the bleomycin model. Both MCP‐1 and MIP‐1α are expressed in a time‐dependent manner after bleomycin challenge, and passive immunization of these animals with either anti‐MIP‐1α or anti‐MCP‐1 antibodies attenuated leukocyte accumulation. In addition, we have identified specific cell types expressing MCP‐1 or MIP‐1α by in situ hybridization and immunohistochemical localization, respectively. Furthermore, our results indicate that MIP‐1α expression is mediated by alveolar macrophage‐derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis. Finally, anti‐MIP‐1α therapy attenuated fibrosis, providing direct evidence for its involvement in fibrotic pathology. Our work has clearly established that the C‐C chemokines MCP‐1 and MIP‐1α are expressed and contribute to the initiation and maintenance of the bleomycin‐induced pulmonary lesion. J. Leukoc. Biol. 57: 782–787; 1995.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141648/1/jlb0782.pd

The role of the formyl-peptide receptor in multi-organ fibrosis mechanisms

PhD ThesisMitochondrial Damage-associated molecular patterns (mtDAMPs) are an emerging source of endogenous alarmins. N-formylated peptides bind members of the formyl-peptide receptor (FPR) family. From its original role in chemotaxis of immune cells towards sites of infection the part that this G-protein coupled receptor (GPCR) plays in the human body is expanding with expression evident in cells of non-phagocyte origin as well as neutrophils and macrophage. To investigate how FPR1 affects the development of pulmonary fibrosis the bleomycin acute injury in vivo model was employed as its pathogenesis shares features with Idiopathic pulmonary fibrosis (IPF). Transgenic mice lacking functional fpr1 displayed a reduced inflammatory profile and fibrotic phenotype at acute and end-stage endpoints respectively post-bleomycin instillation. In vivo models of fibrosis in different organs such as the liver and kidney there was not the same protective effect with deletion of fpr1 as with acute bleomycin lung injury mechanism. This in turn brought the pathogenesis of the in vivo models into question particularly due to the abundance of fpr1 expression on neutrophils, the first line of defense of the immune system. By depleting neutrophils prior to the bleomycin injury the nature of these myeloid cells in this lung fibrosis model and through evaluation of the inflammatory and fibrotic phases post-instillation it is evident that these cells play a major role in how the disease develops. Translation to the human disease (IPF) was a vital step to elucidate the true role of FPR1 in chronic fibrosis mechanisms. Expression was demonstrated by immunofluorescence in CD45+ leukocytes as well as in isolated fibroblasts. This was corroborated by mRNA levels in primary cultured cells when FPR1 expression was ‘primed’ by inflammatory stimuli such as lipopolysaccharide (LPS). With effects observed in a murine setting and also in primary tissue/cells the FPR1 effect may be microenvironment/neutrophil dependent

Gene profiling of lung toxicity

Bleomycin is a potent anti-tumour compound used in the treatment of squamous cell carcinomas. An unfortunate side effect of this drug is pulmonary toxicity. The onset of this damage manifests as mild oedema and inflammation which eventually develops into pulmonary fibrosis. The ability to correctly identify patients showing early signs of lung injury could significantly reduce the morbidity associated with bleomycin treatment. As such, this study was undertaken to identify genetic markers of early oedema and inflammation. A model of mild pulmonary injury was induced by bleomycin. Conventional quantitative analysis of broncho-alveolar lavage was used to indicate the severity of the oedematous response, whilst morphological changes were identified by histology and electron microscopy. Macroarrays were used to measure the expression of multiple genes during mild, progressive and severe oedema. Following normalisation and statistical analysis, gene expression patterns were compared from saline- and bleomycin-treated rats. A variety of genes were differentially expressed during each model, with the number increasing with the severity of the oedema. A cluster and two individual genes were consistently expressed across two of the models of oedema. The magnitude of the changes in gene expression were quantified and confirmed by quantitative PCR. In summary, complete toxicological and histological characterisation of the bleomycin-induced model of pulmonary injury successfully identified specific endpoints of injury. This model proved to be ideal for studying differential gene expression in response to drug-induced pulmonary oedema. A cluster of ion channels and trafficking genes has the potential to act as a biomarker. Two specific genetic markers (Na+/CI- betaine/GABA transporter, glucocorticoid receptor), and a protein marker (cocoacrisp) have been identified for the oedema. In addition to these genes and protein being potential biomarkers of injury, they are also prospective targets for clinical treatment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Gene profiling of lung toxicity

Bleomycin is a potent anti-tumour compound used in the treatment of squamous cell carcinomas. An unfortunate side effect of this drug is pulmonary toxicity. The onset of this damage manifests as mild oedema and inflammation which eventually develops into pulmonary fibrosis. The ability to correctly identify patients showing early signs of lung injury could significantly reduce the morbidity associated with bleomycin treatment. As such, this study was undertaken to identify genetic markers of early oedema and inflammation. A model of mild pulmonary injury was induced by bleomycin. Conventional quantitative analysis of broncho-alveolar lavage was used to indicate the severity of the oedematous response, whilst morphological changes were identified by histology and electron microscopy. Macroarrays were used to measure the expression of multiple genes during mild, progressive and severe oedema. Following normalisation and statistical analysis, gene expression patterns were compared from saline- and bleomycin-treated rats. A variety of genes were differentially expressed during each model, with the number increasing with the severity of the oedema. A cluster and two individual genes were consistently expressed across two of the models of oedema. The magnitude of the changes in gene expression were quantified and confirmed by quantitative PCR. In summary, complete toxicological and histological characterisation of the bleomycin-induced model of pulmonary injury successfully identified specific endpoints of injury. This model proved to be ideal for studying differential gene expression in response to drug-induced pulmonary oedema. A cluster of ion channels and trafficking genes has the potential to act as a biomarker. Two specific genetic markers (Na+/CI- betaine/GABA transporter, glucocorticoid receptor), and a protein marker (cocoacrisp) have been identified for the oedema. In addition to these genes and protein being potential biomarkers of injury, they are also prospective targets for clinical treatment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Gene profiling of lung toxicity

Bleomycin is a potent anti-tumour compound used in the treatment of squamous cell carcinomas. An unfortunate side effect of this drug is pulmonary toxicity. The onset of this damage manifests as mild oedema and inflammation which eventually develops into pulmonary fibrosis. The ability to correctly identify patients showing early signs of lung injury could significantly reduce the morbidity associated with bleomycin treatment. As such, this study was undertaken to identify genetic markers of early oedema and inflammation. A model of mild pulmonary injury was induced by bleomycin. Conventional quantitative analysis of broncho-alveolar lavage was used to indicate the severity of the oedematous response, whilst morphological changes were identified by histology and electron microscopy. Macroarrays were used to measure the expression of multiple genes during mild, progressive and severe oedema. Following normalisation and statistical analysis, gene expression patterns were compared from saline- and bleomycin-treated rats. A variety of genes were differentially expressed during each model, with the number increasing with the severity of the oedema. A cluster and two individual genes were consistently expressed across two of the models of oedema. The magnitude of the changes in gene expression were quantified and confirmed by quantitative PCR. In summary, complete toxicological and histological characterisation of the bleomycin-induced model of pulmonary injury successfully identified specific endpoints of injury. This model proved to be ideal for studying differential gene expression in response to drug-induced pulmonary oedema. A cluster of ion channels and trafficking genes has the potential to act as a biomarker. Two specific genetic markers (Na+/CI- betaine/GABA transporter, glucocorticoid receptor), and a protein marker (cocoacrisp) have been identified for the oedema. In addition to these genes and protein being potential biomarkers of injury, they are also prospective targets for clinical treatment

Implications de la voie RhoA/Rho-kinases dans la physiopathologie des atteintes vasculaires et interstitielles pulmonaires des maladies respiratoires chroniques (études humaines et expérimentales chez la souris)

La voie RhoA/Rho-kinases (ROCK) joue un rôle important dans la physiopathologie de l hypertension pulmonaire (HTP) par son implication dans le dysfonctionnement endothélial, la constriction et le remodelage des vaisseaux pulmonaires. Selon les classifications internationales, la bronchopneumopathie chronique obstructive (BPCO) et la pneumopathie infiltrante diffuse (PID) sont deux causes fréquentes d HTP ayant en commun plusieurs mécanismes physiopathologiques dont le dysfonctionnement endothélial, le remodelage vasculaire et la fibrose parenchymateuse. Les objectifs de ce travail étaient d étudier le rôle de la voie RhoA/ROCK dans la physiopathologie de la BPCO et de la PID avec ou sans HTP et de préciser les anomalies moléculaires liées à la perturbation de la signalisation de cette voie dans chacune de ces situations.Le dysfonctionnement endothélial est un événement essentiel dans l initiation et la progression de la BPCO. L activation de la voie RhoA/ROCK dans le dysfonctionnement endothélial systémique et pulmonaire a été mise en évidence chez les tabagiques avec ou sans BPCO. Les résultats de notre première étude montrent l existence d une activation de la voie RhoA/ROCK au niveau des artères pulmonaires chez les patients BPCO ayant un dysfonctionnement endothélial, et une corrélation entre l activité de la RhoA et l expression génique et l activité de la NO synthase endothéliale (NOS-3).L HTP est une complication grave des PID. Nous avons montré dans notre deuxième étude l implication de la voie RhoA/ROCK dans la réponse inflammatoire et la fibrose pulmonaire (FP) dans un modèle murin de PID induite par injection intratrachéale de bléomycine (BLM). Nous avons ensuite testé l effet préventif du fasudil, un inhibiteur des ROCK, sur l apparition de la FP et l HTP expérimentales induites par la BLM. Les résultats de cette deuxième étude montrent que la FP et l HTP sont associées à une activation de la voie RhoA/ROCK dans ce modèle murin et que le fasudil inhibe la réponse inflammatoire, la FP et l HTP, via l inhibition de la phosphorylation de Smad2/3 de la voie de signalisation par le TGF-b1.La FP et l HTP représentent deux causes principales de mortalité liée à la sclérodermie systémique (ScS). Nous avons étudié le rôle de la voie RhoA/ROCK dans la physiopathologie de la fibrose cutanée et l atteinte pulmonaire dans un modèle murin de ScS induite par injection intradermique d acide hypochloreux (HOCl). Les résultats de cette troisième étude montrent l association entre la fibrose cutanée induite par l HOCl et l activation de la voie RhoA/ROCK au niveau de la peau, et l effet préventif du fasudil sur la fibrose cutanée et pulmonaire, en partie via l inhibition de la phosphorylation de Smad2/3 et de l activation des protéines ERK1/2. Ces résultats suggèrent l implication de la voie RhoA/ROCK dans la physiopathologie de la BPCO et de la PID avec ou sans HTP. La voie RhoA/ROCK pourrait de ce fait représenter une nouvelle cible thérapeutique dans la BPCO et la PID avec ou sans HTP.Mots-clés : RhoA, Rho-kinases, fasudil, BPCO, fibrose pulmonaire, hypertension pulmonaire.The RhoA/Rho-kinases (ROCK) pathway plays a pivotal role in the pathophysiology of pulmonary hypertension (PH) as its abnormal activation leads to endothelial dysfunction, sustained vasoconstriction and pulmonary vascular remodeling. According to the international classification of PH, chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) represent two main causes of PH associated with chronic respiratory diseases. These two causes have in common major pathophysiological mechanisms such as endothelial dysfunction, vascular remodeling and interstitial fibrosis. The aims of the present study were to investigate the role of the RhoA/ROCK pathway in the pathophysiology of lung vascular and interstitial injuries in COPD and ILD with or without development of PH, and to study the molecular mechanisms associated with regulation of the RhoA/ROCK pathway in each of these situations.The pulmonary endothelial dysfunction is an essential event in the initiation and progression of COPD. Although the role of the RhoA/Rho-kinase pathway in pulmonary endothelial dysfunction has been demonstrated in smokers with normal lung function, little is known about its role in patients with COPD. The results of our first study demonstrated an increase in RhoA and ROCK activity in pulmonary arteries of patients with COPD, simultaneously with an altered pulmonary endothelial-dependent vasodilation. The increased RhoA activity in patients with COPD was correlated with an impairment of the gene expression and activity of endothelial NO synthase (eNOS).PH associated with pulmonary fibrosis (PF) considerably worsens prognosis of ILD. The results of our second study showed an activation of the RhoA/ROCK pathway in lung tissues of mice intoxicated by intratracheal instillation of bleomycin (BLM). BLM induced severe PF and PH in mice, associated with an increased RhoA and ROCK activity in the lung. We further demonstrated that long-term treatment with fasudil, a selective ROCK inhibitor, reduced BLM-induced lung inflammation, lung fibrosis and PH in mice, at least in part, via inhibition of Smad2/3 phosphorylation in TGF-b1 signaling.PF and PH represent two leading causes of death in patients with systemic sclerosis (SSc). In our third study, we investigated the role of the RhoA/ROCK pathway in the pathophysiology of skin fibrosis and lung injuries in a murine model of SSc induced by intradermal injection of hypochlorous acid (HOCl). We demonstrated that HOCl-induced skin fibrosis was associated with an activation of the RhoA/ROCK pathway in the fibrotic skin, and that long-term treatment with fasudil reduced both skin and lung fibrosis through inhibition of the phosphorylation of Smad2/3 and ERK1/2 in the fibrotic skin.These results suggest the implications of the RhoA/ROCK pathway in the pathophysiology of lung vascular and interstitial injuries in COPD and ILD with and without development of PH. The RhoA/ROCK pathway might be a promising therapeutic target for patients with COPD or ILD with and without PH.PARIS5-Bibliotheque electronique (751069902) / SudocSudocFranceF