sirolimus and Hyperoxia

Our previous studies have shown that calcitonin gene-related peptide (CGRP) exerts protective effects on the acute lung injury induced by oxidative stress. This study was aimed to investigate whether autophagy was involved in the protection of CGRP against oxidative stress-induced lung injury in neonatal rats. Newborn Sprague-Dawley (SD) rats were randomly divided into five groups: Control group, oxidative stress model group (Model group), Model + CGRP group, Model + CGRP + Rapamycin (an autophagy agonist) group, and Model + CGRP + LY294002 (an autophagy inhibitor) group. The model of hyperoxia-induced lung injury was established by continuous inhalation of oxygen (FiO

Topics: Acute Lung Injury; Animals; Animals, Newborn; Autophagy; Calcitonin; Calcitonin Gene-Related Peptide; Caspase 3; Hyperoxia; Lung; Lung Injury; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Sirolimus

To investigate the effect and significance of mammalian target of rapamycin (mTOR) inhibitors on the expression of α-SMA in lung injury induced by high volume fraction of inspired oxygen (hyperoxygen) in SD rat pups.. Seventy-two Sprague-Dawley rat pups (age: 3 weeks) were randomly divided into air + saline, hyperoxia + saline, hyperoxia + OSI-027, and hyperoxia + rapamycin groups. Animal models were constructed (n = 18). Hyperoxia was induced by continuous administration of 90% oxygen. Normal saline, OSI-027, and rapamycin are administered by intraperitoneal injection on 1d, 3d, 6d, 8d, 10d, 13d of the observation period, respectively. Following assessments were made on the 3rd, 7th, and 14th day of modeling: pathological changes in lung tissues, lung injury score, Western Blot to assess the distribution and expressions of mTOR, pS6K1, and α-SMA protein in lung tissues.. In terms of time factors, the protein expressions of mTOR, pS6K1, and α-SMA increased with time. Except for the air group, the lung injury scores of the other groups increased with time, In terms of grouping factors, lung injury score in the air group was significantly lower than that in the other groups. In the hyperoxia group, the protein expressions of mTOR, PS6K1, and α-SMA were significantly higher than those in the other groups. The lung injury score in the hyperoxia group was significantly higher than that in the other groups. The lung injury score in the hyperoxia OSI group was significantly lower than that in the hyperoxia rapamycin group.. In hyperoxia lung injury, inhibiting the activation of mTOR signaling pathway can effectively reduce the expression of α-SMA; however, only mTORC1/2 dual inhibitor OSI-027 exhibited an anti-proliferative effect, and alleviated hyperoxia-induced lung injury and fibrosis in SD rat pups.

Topics: Actins; Animals; Female; Fibrosis; Hyperoxia; Imidazoles; Lung; Lung Injury; Male; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Rats; Rats, Sprague-Dawley; Ribosomal Protein S6 Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Triazines

Rapamycin inhibits the mammalian target of rapamycin (mTOR) activity and has been proven effective for the treatment of lung injury.. The objective of this study was to investigate the roles of the mTOR pathway and its inhibitor rapamycin in the repair of hyperoxia-induced acute lung injury (ALI).. Firstly, premature rat lung fibroblast L929 cells were cultured under different oxygen concentrations (40%, 60%, and 90%). At day 3, 7 and 14 after exposure, MTT assay and flow cytometry were used to evaluate the effect of oxygen stress on cell viability and apoptosis of L929 cells, respectively. Secondly, microscopy, MTT assay and flow cytometry was used to investigate the effect of 10 nM rapamycin on 90% O2 exposed L929 cells. We also used small interfering RNAs (siRNAs) to abrogate the expression of mTOR in 90% O2 exposed L929 cells, and then evaluated the apoptosis and cell viability using flow cytometry and the MTT assay, respectively. In addition, western blot was used to detect the protein expression of Bcl-2, p53, TGF-β and connective tissue growth factor (CTGF). A hyperoxia-induced lung injury model was established in Sprague Dawley (SD) rats in order to evaluate the histopathological changes in lung tissues and expression of the mTOR pathway and fibrosis related factors.. Exposure to 40%, 60% or 90% oxygen all significantly inhibited the growth of L929 cells. Application of 10 nM rapamycin was found to effectively promote apoptosis of 90% O2 exposed L929 cells. In addition, mTOR siRNA promoted the apoptosis and inhibited the growth of L929 cells. Rapamycin inhibited the activation of the mTOR signaling pathway, down-regulated the expression of downstream proteins p70S6K and 4EBP1, reduced the collagen deposition and the production of fibrosis-inducing factors, including TGF-β and CTGF in hyperoxia-induced lung injury rats.. Rapamycin may be useful for the treatment of hyperoxia-induced acute lung injury (ALI) by inhibiting the activation of mTOR signaling pathway.

Topics: Acute Lung Injury; Animals; Apoptosis; Hyperoxia; Lung; Rats; Rats, Sprague-Dawley; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Bronchopulmonary dysplasia (BPD) is a severe respiratory complication in preterm infants. This study reveals the molecular mechanism of autophagic agonists regulating the Nrf2-ARE pathway via p62 to improve alveolar development in BPD rats.. Newborn Sprague-Dawley rats were randomly exposed to a hyperoxic environment (FiO. At the levels of lung tissue and primary type II alveolar epithelial cells, the enhanced binding between phosphorylated p62 and Keap1 disrupted the nuclear transport of Nrf2. The activated Nrf2 was insufficient to reverse alveolar simplification. The autophagy agonist was able to inhibit p62 phosphorylation, promote Keap1 degradation, increase Nrf2 nuclear transport, augment downstream antioxidant enzyme expression, and enhance antioxidant capacity, thereby improving the simplification of alveolar structure in BPD rats.. The use of autophagy agonists to enhance the Nrf2-ARE pathway activity and promote alveolar development could be a novel target in antioxidant therapy for BPD.

Topics: Animals; Animals, Newborn; Antioxidant Response Elements; Antioxidants; Autophagy; Bronchopulmonary Dysplasia; Disease Models, Animal; Humans; Hyperoxia; Infant, Newborn; Kelch-Like ECH-Associated Protein 1; Mice; NF-E2-Related Factor 2; Pulmonary Alveoli; Rats; Rats, Sprague-Dawley; Sirolimus