<i>Background:</i> Markers of airway inflammation and oxidative stress have been mainly investigated in moderate/severe chronic obstructive pulmonary disease (COPD) or during its exacerbation. They have not been compared in noninvasive specimens such as exhaled breath condensate (EBC) and induced sputum in healthy nonsymptomatic smokers or in those who have symptoms and are at risk for COPD development. <i>Objectives:</i> To compare the relative proportions of 2 potential COPD biomarkers, 8-isoprostane and interleukin- 8 (IL-8) in the induced sputum and EBC sampled from the same subjects: nonsmokers (n = 14), healthy smokers (n = 17) and symptomatic smokers (n = 9) who are considered to be at risk for COPD. COPD patients with acute exacerbation (n = 10) were employed as positive controls. <i>Methods:</i> The levels of the aforementioned biomarkers in induced sputum and EBC were investigated using commercial biochemical techniques. <i>Results:</i> In induced sputum, the levels of 8-isoprostane and IL-8 were at least 10-fold higher compared to EBC levels in all groups. Healthy nonsmokers had the lowest levels, and patients with exacerbation of COPD the highest levels of 8-isoprostane in induced sputum and EBC. The same observation held true for IL-8 in induced sputum. Inverse correlations with lung function parameters were observed for both mediators. <i>Conclusions:</i> The levels of both potential markers were clearly higher in the induced sputum than in EBC. The results point to an advantage of induced sputum over EBC for assessing the degree of airway oxidative stress and inflammation in smokers with a potential risk for COPD development.
Rationale: Members of the transforming growth factor (TGF)-β superfamily, including TGF-βs and bone morphogenetic proteins (BMPs), are essential for the maintenance of tissue homeostasis and regeneration after injury. We have observed that the BMP antagonist, gremlin, is highly up-regulated in idiopathic pulmonary fibrosis (IPF).Objectives: To investigate the role of gremlin in the regulation of BMP signaling in pulmonary fibrosis.Methods: Progressive asbestos-induced fibrosis in the mouse was used as a model of human IPF. TGF-β and BMP expression and signaling activities were measured from murine and human fibrotic lungs. The mechanism of gremlin induction was analyzed in cultured lung epithelial cells. In addition, the possible therapeutic role of gremlin inhibition was tested by administration of BMP-7 to mice after asbestos exposure.Measurements and Main Results: Gremlin mRNA levels were up-regulated in the asbestos-exposed mouse lungs, which is in agreement with the human IPF biopsy data. Down-regulation of BMP signaling was demonstrated by reduced levels of Smad1/5/8 and enhanced Smad2 phosphorylation in asbestos-treated lungs. Accordingly, analyses of cultured human bronchial epithelial cells indicated that asbestos-induced gremlin expression could be prevented by inhibitors of the TGF-β receptor and also by inhibitors of the mitogen-activated protein kinase kinase/extracellular signal-regulated protein kinase pathways. BMP-7 treatment significantly reduced hydroxyproline contents in the asbestos-treated mice.Conclusions: The TGF-β and BMP signaling balance is important for lung regenerative events and is significantly perturbed in pulmonary fibrosis. Rescue of BMP signaling activity may represent a potential beneficial strategy for treating human pulmonary fibrosis.
Idiopathic pulmonary fibrosis (IPF) is characterized by activation and injury of epithelial cells, the accumulation of connective tissue and changes in the inflammatory microenvironment. The bone morphogenetic protein (BMP) inhibitor protein gremlin-1 is associated with the progression of fibrosis both in human and mouse lung. We generated a transgenic mouse model expressing gremlin-1 in type II lung epithelial cells using the surfactant protein C (SPC) promoter and the Cre-LoxP system. Gremlin-1 protein expression was detected specifically in the lung after birth and did not result in any signs of respiratory insufficiency. Exposure to silicon dioxide resulted in reduced amounts of lymphocyte aggregates in transgenic lungs while no alteration in the fibrotic response was observed. Microarray gene expression profiling and analyses of bronchoalveolar lavage fluid cytokines indicated a reduced lymphocytic response and a downregulation of interferon-induced gene program. Consistent with reduced Th1 response, there was a downregulation of the mRNA and protein expression of the anti-fibrotic chemokine CXCL10, which has been linked to IPF. In human IPF patient samples we also established a strong negative correlation in the mRNA expression levels of gremlin-1 and CXCL10. Our results suggest that in addition to regulation of epithelial-mesenchymal crosstalk during tissue injury, gremlin-1 modulates inflammatory cell recruitment and anti-fibrotic chemokine production in the lung.
Chronic Obstructive Pulmonary Disease (COPD), a lung disease related to smoking, is one of the leading causes of chronic morbidity and mortality around the world. One goal in COPD research is the identification of biomarkers for early diagnosis of the disease. Here, we sought COPD-specific changes in the proteome from human lung tissue. This revealed increased levels of surfactant protein A (SP-A) in COPD but not in the normal or fibrotic lung. The results were confirmed by immunohistochemistry, morphometry and Western blotting. Furthermore, elevated SP-A protein levels were detected from the induced sputum supernatants of COPD patients. The levels of other surfactant proteins (SP-B, SP-C, SP-D) were not altered. Our results suggest that SP-A is linked to the pathogenesis of COPD and could be considered as a potential COPD biomarker.
Abstract Activin A and B, members of the TGF-β superfamily, are regulators of differentiation, inflammation and wound healing. Dimeric activins bind to transmembrane activin type I and type II receptors and induce signaling through activation of the canonical Smad2/3 pathway as well as through activation of MAPK pathways. Depending on the tissue type activins can promote or inhibit cellular growth and/or migration. Activin A has recently been reported to have growth promoting properties in malignant mesothelioma (MM). MM is a rare and aggressive tumor originating most commonly from pleural mesothelial cells. It is asbestos exposure related malignancy that takes decades to develop. MM tumors are highly invasive and extremely resistant to conventional cancer therapy. Novel diagnostic markers and drug targets are urgently needed. We have characterized the expression of activins, follistatins and activin receptors in mesothelioma tumors and cultured mesothelioma cells. In addition, we have identified signaling pathways induced in mesothelioma cells by activin treatment. Expression of activins and receptors in mesothelioma tumors were analyzed by immunohistochemistry. Activins, follistatins and receptors in primary mesothelioma cells and in mesothelioma cell lines were analyzed at the level of mRNA and protein expression. Activation of Smad2/3 and Smad1/5/8 signaling pathways were analyzed by luciferase reporter assays and Western blotting. Activation of MAPK/JNK and MAPK/ERK pathways were analyzed by Western blotting. Immortalized but nonmalignant Met5A cells served as a control cell line. Activin A and B were strongly expressed in mesothelioma tumor tissue. Cultured primary mesothelioma cells and mesothelioma cell lines also expressed higher levels of activin A and B compared to Met5A cells. All activin receptors (ALK3, ALK4, ALK7, ACVR2A, ACVR2B) were found expressed in cultured mesothelioma cells. ACVR2A and ALK7 were significantly overexpressed in all mesothelioma cells. Majority of the mesothelioma cell lines had attenuated Smad2/3 activation upon activin stimulation. In Met5A and H28 cells there was activation of Smad2/3 as well as MAPK/JNK pathways. On the contrary, activation of MAPK/ERK pathway was detected in cells displaying attenuated Smad2/3 activation.Our results show that activin A and B are overexpressed in MM. This together with upregulation of specific activin receptors points to a role for activins in MM progression. Furthermore, we observed that mesothelioma cells have altered responses to activin stimulation, namely attenuation of canonical Smad2/3 signaling and increase in MAPK/ERK signaling. This is likely to have an impact on mesothelioma cell behavior and tumor progression. Citation Format: Jenni A. Tamminen, Mikko Rönty, Eva Sutinen, Arja Pasternack, Olli Ritvos, Marjukka Myllärniemi, Katri Koli. Overexpression of activin A and B as well as altered activation of canonical and non-canonical signaling pathways in malignant mesothelioma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3449. doi:10.1158/1538-7445.AM2014-3449
Microarray studies have shown that matrilysin or matrix metalloproteinase (MMP)‐7 is highly upregulated in the lungs of patients with idiopathic pulmonary fibrosis (IPF), but MMP‐7 protein expression has not been systematically compared between IPF and other interstitial lung diseases. MMP‐7 levels in bronchoalveolar lavage fluid (BALF) were compared to corresponding samples from nonspecific interstitial pneumonia (NSIP), sarcoidosis, and healthy controls. MMP‐7 levels in the BALF were determined by ELISA and localization of MMP‐7 in the lung tissue by immunohistochemistry. MMP‐7 was similarly elevated in the BALF of all these disorders compared to healthy controls (p=0.007). Even control subjects with prolonged cough displayed a tendency towards elevated MMP‐7 expression. There was a negative correlation between BALF MMP‐7 levels and forced expiratory vital capacity (r=−0.348, p=0.02, n=42). In IPF lung, MMP‐7 immunoreactivity appeared predominantly in the fibrotic parenchyma and arterial wall. In sarcoidosis and NSIP, prominent MMP‐7 immunoreactivity was found in areas of inflammation. These results demonstrate that elevated BALF MMP‐7 is not restricted to IPF alone but is also observed in other interstitial lung diseases and cannot be used as a differential diagnostic marker for IPF.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'%3e%3ccircle r='20' fill='%23008'/%3e%3ccircle r='17.5' fill='%23fff'/%3e%3ccircle r='3.5' fill='%23008'/%3e%3cg id='d'%3e%3cg id='c'%3e%3cg id='b'%3e%3cg id='a' fill='%23008'%3e%3ccircle r='.875' transform='rotate(7.5 -8.75 133.5)'/%3e%3cpath d='M0 17.5.6 7 0 2l-.6 5L0 17.5z'/%3e%3c/g%3e%3cuse xlink:href='%23a' transform='rotate(15)'/%3e%3c/g%3e%3cuse xlink:href='%23b' transform='rotate(30)'/%3e%3c/g%3e%3cuse xlink:href='%23c' transform='rotate(60)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='rotate(120)'/%3e%3cuse xlink:href='%23d' transform='rotate(-120)'/%3e%3c/g%3e%3c/svg%3e)