| 1. |
- Chang, Ya-Ting, et al.
(author)
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Antenatal imatinib treatment reduces pulmonary vascular remodeling in a rat model of congenital diaphragmatic hernia
- 2012
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In: American Journal of Physiology - Lung cellular and Molecular Physiology. - : American Physiological Society. - 1040-0605 .- 1522-1504. ; 302:11, s. L1159-L1166
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Journal article (peer-reviewed)abstract
- The pathophysiology of congenital diaphragmatic hernia (CDH) is constituted by pulmonary hypoplasia and pulmonary hypertension (PH). We previously reported successful treatment with imatinib of a patient with CDH. This study examines the effect of antenatal imatinib administration on the pulmonary vasculature in a rat model of CDH. Pregnant rats were given nitrofen to induce CDH. Controls were given olive oil. Half of the CDH fetuses and half of the controls were treated with imatinib antenatally E17-E21, rendering four groups: Control, Control+Imatinib, CDH, and CDH+Imatinib. Lung sections were obtained for morphometry and immunohistochemistry, and protein was purified for Western blot. Effects of nitrofen and imatinib on Ki-67, caspase-3, PDGF-B, and PDGF receptors were analyzed. Imatinib significantly reduced medial wall thickness in pulmonary arteries of rats with CDH. It also normalized lumen area and reduced the proportion of fully muscularized arteries. Imatinib also caused medial thinning in the control group. Cell proliferation was increased in CDH, and this proliferation was significantly reduced by imatinib. PDGF-B and PDGFR-beta were upregulated in CDH, and imatinib treatment resulted in a downregulation. PDGFR-alpha remained unchanged in CDH but was significantly downregulated by imatinib. Antenatal imatinib treatment reduces development of medial wall thickness and restores lumen area in pulmonary arteries in nitrofen-induced CDH. The mechanism is reduced cell proliferation. Imatinib is an interesting candidate for antenatal therapy for PH in CDH, but potential side effects need to be investigated and more specific targeting of PDGF signaling is needed.
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| 2. |
- Ringman Uggla, Andreas, et al.
(author)
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Low pulmonary expression of epithelial Na(+) channel and Na(+), K(+)-ATPase in newborn infants with congenital diaphragmatic hernia
- 2011
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In: Neonatology. - : S. Karger AG. - 1661-7800 .- 1661-7819. ; 99:1, s. 14-22
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Journal article (peer-reviewed)abstract
- BACKGROUND: It has been suggested from several animal studies and clinical observations that congenital diaphragmatic hernia (CDH) with pulmonary hypoplasia is accompanied by a disturbed perinatal ion transport. This could lead to respiratory distress due to slower clearance of fetal lung fluid at birth. OBJECTIVES: The purpose of this study was to determine whether CDH is related to changes in the expression of three rate-limiting transporter proteins in lung epithelium at birth. METHODS: Tracheal aspirate was collected from 12 newborn infants with CDH and from 8 newborn control patients. Sampling was performed at postnatal age 18 and at 43 h in the CDH group and at 18 h in the control group. The protein abundance of α-, β- and γ-epithelial Na(+) channel (ENaC), aquaporin 5 and Na(+), K(+)-ATPase α(1) was analyzed using semiquantitative immunoblotting. RESULTS: The levels of β-ENaC, γ-ENaC and Na(+), K(+)-ATPase α(1) collected at 18 h postnatally were significantly lower in CDH infants compared to control infants. In the CDH group, no significant difference in the expression of the ENaC subunits, Na(+), K(+)-ATPase α(1) or aquaporin 5 could be detected between the two sampling time points. CONCLUSIONS: This downregulation may result in an abnormal lung fluid absorption which could be an important mechanism behind the respiratory distress seen in newborn CDH patients.
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| 3. |
- Ringman Uggla, Andreas
(author)
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Role of ion and water channels for lung growth in congenital diaphragmatic hernia
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Early lung development is based on a continuous cross-talk of growth and transcription factors between the developing lung bud and the surrounding parenchyma. Throughout fetal life, pulmonary growth and differentiation depend on Cl- driven lung liquid secretion. The prospective fetal airways are thus filled with lung liquid and the fetus is provided with oxygen by the mother through the placenta. Cl- secretion involves the basolateral Na+-K+-2Cl- co-transporter 1 (NKCC-1), coupled to an apical Cl- exit pathway. A decrease in lung liquid renders pulmonary hypoplasia, while an in utero applied tracheal occlusion (TO), trapping lung liquid within the airways, results in pulmonary hyperplasia. In order to eliminate residual lung fluid and to make way for an effective gas exchange, the lungs switch prenatally to active fluid absorption by apical Na+ transport through the amiloride sensitive epithelial sodium channel (ENaC-alpha/-beta/-gamma). The basolaterally located Na+, K+- ATPase acts as the primary driving force. Four water channels, aquaporin (AQP) 1, 3, 4 and 5 are also expressed in the lung and may contribute to fluid absorption. Pulmonary hypoplasia is most frequently associated with congenital diaphragmatic hernia (CDH), a birth defect present in 1 in 2000-3000 live newborns; approximately 8% of all major congenital anomalies. About 30 newborns per year are diagnosed with CDH in Sweden. Survival rates differ significantly, but averages on 50%. The disease includes herniation of abdominal viscera into the thoracic cavity through a diaphragmatic defect. The pathophysiology of CDH is constituted by pulmonary hypoplasia (PH) and an increase in lung vessel resistance, resulting in pulmonary artery hypertension (PAH). This leads to respiratory distress at birth. The work in this thesis aimed to explore the role of lung liquid metabolism for the development and function of hypoplastic lungs in CDH. The work also includes a study on a possible new drug candidate for the treatment of PAH in CDH. In study I, we investigated the expression of NKCC-1, ENaC and Na+, K+-ATPase during different developmental stages in a rat model of CDH. NKCC-1 together with beta-ENaC were significantly down-regulated in fetuses with CDH and PH in mid- and late gestation. This indicates that lung liquid metabolism might be affected in CDH and the ability for lung liquid production and absorption may be decreased. In study II, we examined the role of the chloride channels ClC-2, -3 and -5 in the development of hypoplastic lungs and TO-induced hyperplastic lungs. ClC-2 and -3 were both downregulated just before birth in PH lungs, while lung hyperplasia created by TO up-regulated the expression of ClC-2. NKCC-1 showed a tendency towards up-regulation in hyperplastic lungs. ClC-5 were not affected in any group. ClC-2 is therefore an interesting potential target in the development of novel, non-invasive therapies for CDH treatment. In study III, we performed a global gene expression analysis on the nitrofen-induced animal model of CDH. Significantly decreased expression was found for several growth factors and growth factor receptors involved in lung development, transcription factors, water and ion channels including ENaC and AQP1 and -4, genes involved in pulmonary angiogenesis and extracellular matrix formation. These data supports our hypothesis that CDH with PH is connected to a reduced ability for lung liquid clearance at birth and that PH is not mainly a consequence of mechanical compression, but primarily an intrinsic pulmonary disease. In study IV, we conducted a clinical study examining the pulmonary expression of ion and water transporters in newborn CDH patients. beta-ENaC, gamma-ENaC and Na+, K+-ATPase alpha1 collected at 18 h postnatally were significantly lower in CDH infants compared to control infants and remained unchanged on the second day of life. These results support earlier reports from animal studies and may result in an abnormal lung fluid absorption contributing to the respiratory distress in newborn CDH patients. Study V was inspired by successful results from our group after administration of the platelet derived growth factor (PDGF) inhibitor, imatinib, to a CDH patient with intractable PAH. The pulmonary artery pressure decreased and the patient s condition gradually improved. In the present study performed in rats, we showed that the typical medial wall hyperplasia of pulmonary arteries seen in CDH, leading to the increased pulmonary vascular resistance, could be counteracted and almost normalized after antenatal imatinib administration. Imatinib treated CDH fetuses also showed a significant reduction in the number of fully muscularized pulmonary arteries. The increase in smooth muscle cell proliferation which was found in the nitrofen treated rats compared to controls was also significantly reduced by imatinib treatment. We concluded that imatinib is a very interesting candidate as a novel therapeutic approach for counteracting PAH in CDH before birth.
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| 4. |
- Uggla, Andreas Ringman, et al.
(author)
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Expression of chloride channels in trachea-occluded hyperplastic lungs and nitrofen-induced hypoplastic lungs in rats
- 2009
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In: Pediatric surgery international (Print). - : Springer Science and Business Media LLC. - 0179-0358 .- 1437-9813. ; 25:9, s. 799-806
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Journal article (peer-reviewed)abstract
- Congenital diaphragmatic hernia is accompanied by pulmonary hypoplasia. Fetal lung growth is dependent on the secretion of lung liquid, in which Cl- secretion by the pulmonary epithelium plays a crucial role. A decrease of lung liquid production during fetal development renders marked pulmonary hypoplasia, while accelerated fetal lung growth in the form of pulmonary hyperplasia can be achieved by in utero tracheal occlusion (TO). Cl- secretion presumably involves NKCC-1, the primary basolateral Cl- entry pathway in airway epithelia, coupled to an apical Cl- exit pathway. The chloride channels ClC-2, -3 and -5, members of the CLC gene family, are all localized to the apical membrane of fetal respiratory epithelia, which makes them possible candidates for being mediators of fetal apical Cl- secretion. The aim of the study was to examine the potential of ClC-2, -3 and -5 as alternative apical airway epithelial Cl- channels in normal lung development and their possible role in the development of hypoplastic lungs in CDH. We also wanted to examine ClC-2, -3 and -5 together with the NKCC-1 in hyperplastic lungs created by TO. Pregnant Sprague-Dawley rat dams were given nitrofen on gestational day 9.5 to induce pulmonary hypoplasia. Controls were given only olive oil. The rat fetuses were removed on days 17, 19 and 21. Hyperplastic lungs were created by intrauterine TO of rat fetuses on day 19 and the lungs were harvested on day 21. The pulmonary expression of ClC-2, -3, -5 and NKCC-1 was then analyzed using Western blot. We found that the temporal expression of ClC-2 and -3 in normal fetal lungs points toward a developmental regulation. ClC-2 and -3 were also both down-regulated on day 21 in hypoplastic CDH lungs. In TO induced hyperplastic lungs, the levels of ClC-2 were found to be significantly up-regulated. NKCC-1 showed a tendency toward up-regulation in hyperplastic lungs, while ClC-3 showed a tendency to be down-regulated, but no statistically significant changes could be seen. There was no difference between controls and any of the groups for the expression of ClC-5. We show that the developmental changes in ClC-2 and ClC-3 protein expression are negatively affected in hypoplastic CDH lungs. Lung hyperplasia created by TO up-regulates the expression of ClC-2. ClC-2 is therefore an interesting potential target in the development of novel, non-invasive, therapies for CDH treatment.
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