American journal of respiratory cell and molecular biology
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Am. J. Respir. Cell Mol. Biol. · Apr 2014
Inhibition of transglutaminase 2, a novel target for pulmonary fibrosis, by two small electrophilic molecules.
Idiopathic pulmonary fibrosis (IPF) is characterized by progressive fibrotic destruction of normal lung architecture. Due to a lack of effective treatment options, new treatment approaches are needed. We previously identified transglutaminase (TG)2, a multifunctional protein expressed by human lung fibroblasts (HLFs), as a positive driver of fibrosis. ⋯ CDDO and 15d-PGJ2 inhibited the extracellular signal-regulated kinase pathway, resulting in the suppression of TG2 expression. This is the first study to show that small electrophilic compounds inhibit the expression and profibrotic effector functions of TG2, a key promoter of fibrosis. These studies identify new and important antifibrotic activities of these two small molecules, which could lead to new treatments for fibrotic lung disease.
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Am. J. Respir. Cell Mol. Biol. · Apr 2014
Comparative StudySynthetic aminoglycosides efficiently suppress cystic fibrosis transmembrane conductance regulator nonsense mutations and are enhanced by ivacaftor.
New drugs are needed to enhance premature termination codon (PTC) suppression to treat the underlying cause of cystic fibrosis (CF) and other diseases caused by nonsense mutations. We tested new synthetic aminoglycoside derivatives expressly developed for PTC suppression in a series of complementary CF models. Using a dual-luciferase reporter system containing the four most prevalent CF transmembrane conductance regulator (CFTR) nonsense mutations (G542X, R553X, R1162X, and W1282X) within their local sequence contexts (the three codons on either side of the PTC), we found that NB124 promoted the most readthrough of G542X, R1162X, and W1282X PTCs. ⋯ NB124 treatment rescued CFTR function in a CF mouse model expressing a human CFTR-G542X transgene; efficacy was superior to gentamicin and exhibited favorable pharmacokinetic properties, suggesting that in vitro results translated to clinical benefit in vivo. NB124 was also less cytotoxic than gentamicin in a tissue-based model for ototoxicity. These results provide evidence that NB124 and other synthetic aminoglycosides provide a 10-fold improvement in therapeutic index over gentamicin and other first-generation aminoglycosides, providing a promising treatment for a wide array of CFTR nonsense mutations.
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Am. J. Respir. Cell Mol. Biol. · Apr 2014
Angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis protects against lung fibrosis by inhibiting the MAPK/NF-κB pathway.
Accumulating evidence has demonstrated that up-regulation of the angiotensin (Ang)-converting enzyme (ACE)/AngII/AngII type 1 receptor (AT1R) axis aggravates pulmonary fibrosis. The recently discovered ACE2/Ang-(1-7)/Mas axis, which counteracts the activity of the ACE/AngII/AT1R axis, has been shown to protect against pulmonary fibrosis. However, the mechanisms by which ACE2 and Ang-(1-7) attenuate pulmonary fibrosis remain unclear. ⋯ Ang-(1-7) alone markedly stimulated extracellular signal-regulated protein kinase 1/2 phosphorylation and the NF-κB cascade. Up-regulation of the ACE2/Ang-(1-7)/Mas axis protected against pulmonary fibrosis by inhibiting the MAPK/NF-κB pathway. However, close attention should be paid to the proinflammatory effects of Ang-(1-7).
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Am. J. Respir. Cell Mol. Biol. · Mar 2014
Comparative StudyLung phenotype of juvenile and adult cystic fibrosis transmembrane conductance regulator-knockout ferrets.
Chronic bacterial lung infections in cystic fibrosis (CF) are caused by defects in the CF transmembrane conductance regulator chloride channel. Previously, we described that newborn CF transmembrane conductance regulator-knockout ferrets rapidly develop lung infections within the first week of life. Here, we report a more slowly progressing lung bacterial colonization phenotype observed in juvenile to adult CF ferrets reared on a layered antibiotic regimen. ⋯ Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry fingerprinting was used to quantify lung bacteria in 10 CF animals and demonstrated Streptococcus, Staphylococcus, Enterococcus, or Escherichia as the most abundant genera. Interestingly, there was significant overlap in the types of bacteria observed in the lung and intestine of a given CF animal, including bacterial taxa unique to the lung and gut of each CF animal analyzed. These findings demonstrate that CF ferrets develop lung disease during the juvenile and adult stages that is similar to patients with CF, and suggest that enteric bacterial flora may seed the lung of CF ferrets.
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Am. J. Respir. Cell Mol. Biol. · Mar 2014
Glycosyltransferases and glycosaminoglycans in bleomycin and transforming growth factor-β1-induced pulmonary fibrosis.
Glycosaminoglycan (GAG) chains of proteoglycans (PGs) play important roles in fibrosis through cell-matrix interactions and growth factor binding in the extracellular matrix. We investigated the expression and regulation of PG core protein (versican) and key enzymes (xylosyltransferase [XT]-I, β1,3-glucuronosyltransferase [GlcAT]-I, chondroitin-4-sulfotransferase [C4ST]) implicated in synthesis and sulfation of GAGs in bleomycin (BLM) and adenovirus-transforming growth factor (TGF)-β1-induced lung fibrosis in rats. We also studied the role of GlcAT-I or TGF-β1 and the signaling pathways regulating PG-GAG production in primary lung fibroblasts isolated from saline- or BLM-instilled rats. ⋯ Forced expression of TGF-β1 in vivo enhanced versican, XT-I, GlcAT-I, and C4ST-I expression and PG-GAG deposition in rat lungs. Finally, induced expression of GlcAT-I gene in rat lung fibroblasts increased GAG synthesis by these cells. Together, our results provide new insights into the basis for increased PG-GAG deposition in lung fibrosis; inhibition of TGF-β1-mediated or fibrosis-induced PG-GAG production by activin receptor-like kinase 5/p38 inhibitors may contribute to antifibrotic activity.