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Treatment with Geranylgeranylacetone Induces Heat Shock Protein 70 and Attenuates Neonatal Hyperoxic Lung Injury in a Model of Bronchopulmonary Dysplasia.

ABSTRACT: Bronchopulmonary dysplasia (BPD) is a respiratory complication characterized by abnormal alveolar development in premature infants. Geranylgeranylacetone (GGA) can induce heat shock protein (HSP) 70, which has cytoprotective effects against various stressors. Here, we investigated whether GGA protected neonatal lungs from hyperoxic stress in a murine BPD model, and measured the serum HSP70 levels in preterm humans treated with oxygen.Newborn mice were exposed to >90% oxygen and administered GGA or vehicle alone orally on days 1, 2, and 3 of life. At 2 days of age, HSP70 expression in the lung was determined by western blotting. At 8 days of age, the lungs were processed for histological analysis. Radial alveolar count (RAC) and mean linear intercept (MLI) were measured as parameters of alveolarization. Apoptosis was evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and cleaved caspase-3 immunohistochemistry. Serum HSP70 levels in preterm humans treated with oxygen were measured by enzyme-linked immunosorbent assay.GGA administration enhanced the HSP70 expression to two-fold compared with normoxia-exposed and vehicle-treated mice. Hyperoxia reduced HSP70 expression, whereas GGA abrogated the effects. Hyperoxia-exposed mice exhibited more apoptotic cells in lung parenchyma and a more simplified alveolar structure with less RAC and larger MLI than normoxia-exposed mice. GGA suppressed the increase in apoptotic cells and the structural changes of the lungs induced by hyperoxia. Serum HSP70 levels of preterm human infants gradually decreased with age.GGA may attenuate hyperoxic injury in neonatal lungs and thereby may prevent the development of BPD.

SUBMITTER: Tokuriki S

PROVIDER: S-EPMC5522658 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:Myeloperoxidase (MPO), oxidative stress (OS), and endoplasmic reticulum (ER) stress are increased in the lungs of rat pups raised in hyperoxia, an established model of bronchopulmonary dysplasia (BPD). However, the relationship between OS, MPO, and ER stress has not been examined in hyperoxia rat pups. We treated Sprague-Dawley rat pups with tunicamycin or hyperoxia to determine this relationship. ER stress was detected using immunofluorescence, transcriptomic, proteomic, and electron microscopic analyses. Immunofluorescence observed increased ER stress in the lungs of hyperoxic rat BPD and human BPD. Proteomic and morphometric studies showed that tunicamycin directly increased ER stress of rat lungs and decreased lung complexity with a BPD phenotype. Previously, we showed that hyperoxia initiates a cycle of destruction that we hypothesized starts from increasing OS through MPO accumulation and then increases ER stress to cause BPD. To inhibit ER stress, we used tauroursodeoxycholic acid (TUDCA), a molecular chaperone. To break the cycle of destruction and reduce OS and MPO, we used N-acetyl-lysyltyrosylcysteine amide (KYC). The fact that TUDCA improved lung complexity in tunicamycin- and hyperoxia-treated rat pups supports the idea that ER stress plays a causal role in BPD. Additional support comes from data showing TUDCA decreased lung myeloid cells and MPO levels in the lungs of tunicamycin- and hyperoxia-treated rat pups. These data link OS and MPO to ER stress in the mechanisms mediating BPD. KYC's inhibition of ER stress in the tunicamycin-treated rat pup's lung provides additional support for the idea that MPO-induced ER stress plays a causal role in the BPD phenotype. ER stress appears to expand our proposed cycle of destruction. Our results suggest ER stress evolves from OS and MPO to increase neonatal lung injury and impair growth and development. The encouraging effect of TUDCA indicates that this compound has the potential for treating BPD.

Project description:Myeloperoxidase (MPO), oxidative stress (OS), and endoplasmic reticulum (ER) stress are all increased in the lungs of neonatal rat pups raised in hyperoxia (HOX, >90% O2), an established model of bronchopulmonary dysplasia (BPD). However, the relationship between OS, MPO, and ER stress has not been examined in HOX rat pups. To determine the relationship between OS, MPO, and ER stress in BPD we treated Sprague-Dawley neonatal rat pups with Tunicamycin (Tun) or with HOX. Tun directly induces ER stress and simplifies neonatal lung alveolarization. Previously, we showed that HOX induces a cycle of destruction that we hypothesize through increased OS, MPO, and ER stress to induce BPD. To inhibit ER stress specifically, we used tauroursodeoxycholic acid (TUDCA), a molecular chaperone. To break the cycle of destruction and reduce OS and MPO we used N-acetyl-lysyltyrosylcysteine-amide (KYC), a systems pharmacology agent. Lung structure was studied morphometrically. ER stress was detected using immunofluorescence (IF), transcriptomic, proteomic, and electron microscopic analyses. Increased ER stress was observed in the lungs of HOX rat pups and also in human BPD lungs by IF. Morphometric and proteomic studies of rat lungs showed that Tun treatment decreased lung complexity and increased ER stress and BPD severity. The fact that TUDCA improved lung complexity in Tun-treated neonatal rat pups, and decreased BPD induced by HOX provides strong support for the idea that ER stress plays a causal role in BPD. Additional support comes from data showing TUDCA decreased lung myeloid cells and MPO levels in the lungs of both Tun- and HOX-treated neonatal rat pups. These data link OS and MPO to ER stress in the mechanisms mediating BPD. KYC's effective inhibition of ER stress in the lungs of Tun-treated rat pups provides additional support for the idea that MPO-induced ER stress plays a direct causal role in BPD. Thus, ER stress appears to expand our proposed cycle of destruction. Our results suggest ER stress evolves from OS and MPO to increase neonatal lung injury and impaired neonatal lung growth and development. The encouraging effect of TUDCA indicates chemical chaperone has the potential in treating BPD. Using multiomic data to investigate the role of endoplasmic reticulum stress in the development of BPD in rat model.

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Treatment with Geranylgeranylacetone Induces Heat Shock Protein 70 and Attenuates Neonatal Hyperoxic Lung Injury in a Model of Bronchopulmonary Dysplasia.

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