Search

Background: Hyperoxia downregulates the tight junction (TJ) proteins of the alveolar epithelium and leads to barrier dysfunction. Previous study has showed that STE20/SPS1-related proline/alanine-rich kinase (SPAK) interferes with the intestinal barrier function in mice. The aim of the present study is to explore the association between SPAK and barrier function in the alveolar epithelium after hyperoxic exposure., Methods: Hyperoxic acute lung injury (HALI) was induced by exposing mice to > 99% oxygen for 64 h. The mice were randomly allotted into four groups comprising two control groups and two hyperoxic groups with and without SPAK knockout. Mouse alveolar MLE-12 cells were cultured in control and hyperoxic conditions with or without SPAK knockdown. Transepithelial electric resistance and transwell monolayer permeability were measured for each group. In-cell western assay was used to screen the possible mechanism of p-SPAK being induced by hyperoxia., Results: Compared with the control group, SPAK knockout mice had a lower protein level in the bronchoalveolar lavage fluid in HALI, which was correlated with a lower extent of TJ disruption according to transmission electron microscopy. Hyperoxia down-regulated claudin-18 in the alveolar epithelium, which was alleviated in SPAK knockout mice. In MLE-12 cells, hyperoxia up-regulated phosphorylated-SPAK by reactive oxygen species (ROS), which was inhibited by indomethacin. Compared with the control group, SPAK knockdown MLE-12 cells had higher transepithelial electrical resistance and lower transwell monolayer permeability after hyperoxic exposure. The expression of claudin-18 was suppressed by hyperoxia, and down-regulation of SPAK restored the expression of claudin-18. The process of SPAK suppressing the expression of claudin-18 and impairing the barrier function was mediated by p38 mitogen-activated protein kinase (MAPK)., Conclusions: Hyperoxia up-regulates the SPAK-p38 MAPK signal pathway by ROS, which disrupts the TJ of the alveolar epithelium by suppressing the expression of claudin-18. The down-regulation of SPAK attenuates this process and protects the alveolar epithelium against the barrier dysfunction induced by hyperoxia.

Acute lung injury (ALI) is characterized by enhanced permeability of the air-blood barrier, pulmonary edema, and hypoxemia. MicroRNA-21 (miR-21) was shown to be involved in pulmonary remodeling and the pathology of ALI, and we hypothesized that miR-21 knock-out (KO) reduces injury and remodeling in ALI. ALI was induced in miR-21 KO and C57BL/6N (wildtype, WT) mice by an intranasal administration of 75 µg lipopolysaccharide (LPS) in saline ( n = 10 per group). The control mice received saline alone ( n = 7 per group). After 24 h, lung function was measured. The lungs were then excised for proteomics, cytokine, and stereological analysis to address inflammatory signaling and structural damage. LPS exposure induced ALI in both strains, however, only WT mice showed increased tissue resistance and septal thickening upon LPS treatment. Septal alterations due to LPS exposure in WT mice consisted of an increase in extracellular matrix (ECM), including collagen fibrils, elastic fibers, and amorphous ECM. Proteomics analysis revealed that the inflammatory response was dampened in miR-21 KO mice with reduced platelet and neutrophil activation compared with WT mice. The WT mice showed more functional and structural changes and inflammatory signaling in ALI than miR-21 KO mice, confirming the hypothesis that miR-21 KO reduces the development of pathological changes in ALI.

Hyperoxia‑induced acute lung injury (HALI) as one of the most common complications in patents on mechanical ventilation, and there are no efficient methods to overcome this at present. It was hypothesized that microRNA 21‑5p(miR‑21‑5p) can promote the survival of type II alveolar epithelial cells (AECII), alleviating HALI. The present study aimed to combine gene chip analysis with the overexpression miR‑21‑5p to develop a novel therapeutic option for HALI. It was found that AECII apoptosis was an important pathogenic event in the development of HALI, and the overexpression of miR‑21‑5p prevented HALI, associated with reducing AECII apoptosis. These results were obtained using adenoviral/lentiviral vectors, which overexpressed miR‑21‑5p, to transfect AECII cells in vitro and in vivo. It was found that the overexpression of miR‑21‑5p reduced the apoptotic rate of the AECII cells. In addition, miR‑21‑5p decreased the ratio of B‑cell lymphoma 2 (Bcl‑2)‑associated X protein/Bcl‑2 and the expression of caspase‑3. It was also revealed that the overexpression of miR‑21‑5p alleviated acute lung injury in adult rats exposed to a hyperoxic environment. These results suggest that miR‑21‑5p may become a novel therapeutic option for patients with HALI, by protecting AECII cells from apoptosis.

Sulfur mustard (SM), a bifunctional alkylating agent that causes severe lung damage, is a significant threat to both military and civilian populations. The mechanisms mediating the cytotoxic effects of SM are unknown and were investigated in this study. The purpose of this study was to establish a rat model of SM-induced lung injury to observe the resulting changes in the lungs. Male rats (Sprague Dawley) were anesthetized, intratracheally intubated, and exposed to 2 mg/kg of SM by intratracheal instillation. Animals were euthanized 6, 24, 48, and 72 h post-exposure, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. Exposure of rats to SM resulted in rapid pulmonary toxicity, including partial bronchiolar epithelium cell shedding, focal ulceration, and an increased amount of inflammatory exudate and number of cells in the alveoli. There was also evidence that the protein content and cell count of BALF peaked at 48 h, and the alveolar septum was widened and filled with lymphocytes. SM exposure also resulted in partial loss of type I alveolar epithelial cell membranes, fuzzy mitochondrial cristae, detachment and dissociation of ribosomes attached to the surface of rough endoplasmic reticulum, cracked, missing, and disorganized microvilli of type II alveolar epithelial cells, and increased apoptotic cells in the alveolar septum. The propylene glycol control group, however, was the same as the normal group. These data demonstrate that the mechanism of a high concentration of SM (2 mg/kg) induced acute lung injury include histologic changes, inflammatory reactions, apoptosis, oxidative stress, and nuclear DNA damage; the degree of injury is time dependent., (© The Author(s) 2014.)

Objective: To detect the ultrastructural changes in rabbits with type II decompression sickness (DCS), and study the therapeutic effects of hyperbaric oxygen (HBO)., Methods: Twenty-seven male New Zealand rabbits were randomly divided equally into the DCS group, HBO treatment group and control group. Experimental models of each group were prepared. Lung apex tissues were harvested to prepare paraffin- and EPON812-embedded tissues., Results: In the DCS group, macroscopic and histological examination revealed severe and rapid damage to lung tissue. Ultrastructural examination revealed exudation of red blood cells in the alveolar space. Type I alveolar epithelial cells exhibited retracted cell processes and swollen mitochondria, and type II cells showed highly swollen mitochondria and decrease in cytoplasmic lamellar bodies. Dilatation and congestion of capillary vessels were accompanied by swelling of endothelial cells and incomplete basement membrane. In the HBO treatment group, the findings were somewhat similar to those in the DCS group, but the extent of damage was lesser. Only a small amount of tiny bubbles could be seen in the blood vessels. Type I alveolar epithelia cells and endothelial cells of the capillaries illustrated slight shortening of cells, swollen cytoplasm and decreased cell processes. Type II alveolar epithelial cells showed slight swelling of the mitochondria, decreased vacuolar degeneration of lamellar bodies, and increase in the number of free ribosomes., Conclusions: Our microscopic and ultrastructural findings confirm that the lung is an important organ affected by DCS. We also confirmed that HBO can alleviate DCS-induced pulmonary damage.

Background: Paraquat poisoning is well known for causing multiple organ function failure (MODS) and high mortality. Acute lung injury and advanced pulmonary fibrosis are the most serious complications. Bosentan is a dual endothelin receptor antagonist. It plays an important role in treating PF. There is no related literature on the use of bosentan therapy for paraquat poisoning., Objective: To study the use of bosentan to treat acute lung injury and pulmonary fibrosis as induced by paraquat., Method: A total of 120 adult Wister male rats were randomly assigned to three groups: the paraquat poisoning group (rats were intragastrically administered with paraquat at 50 mg/kg body weight once at the beginning); the bosentan therapy group (rats were administered bosentan at 100 mg/kg body weight by intragastric administration half an hour after paraquat was administered, then the same dose was administered once a day); and a control group (rats were administered intragastric physiological saline). On the 3rd, 7th, 14th, and 21st days following paraquat exposure, rats were sacrificed, and samples of lung tissue and venous blood were collected. The levels of transforming growth factor-β1 (TGF-β1), endothelin-1 (ET-1), and hydroxyproline (HYP) in the plasma and lung homogenate were determined. Optical and electronic microscopes were used to examine pathological changes., Result: The TGF-β1, ET-1, and HYP of the paraquat poisoning group were significantly higher than in the control group, and they were significantly lower in the 21st day therapy group than in the paraquat poisoning group on the same day. Under the optical and electronic microscopes, lung tissue damage was observed to be more severe but was then reduced after bosentan was administered., Conclusion: Bosentan can reduce inflammation factor release. It has a therapeutic effect on acute lung injury as induced by paraquat.

Background: Nuclear factor-κB (NF-κB) is a central transcriptional factor and a pleiotropic regulator of many genes involved in acute lung injury. Andrographolide is found in the plant of Andrographis paniculata and widely used in Traditional Chinese Medicine, exhibiting potently anti-inflammatory property by inhibiting NF-κB activity. The purpose of our investigation was designed to reveal the effect of andrographolide on various aspects of LPS induced inflammation in vivo and in vitro., Methods and Results: In vivo, BALB/C mice were subjected to LPS injection with or without andrographolide treatments to induce ALI model. In vitro, MLE-12 cells were stimulated with LPS in the presence and absence of andrographolide. In vivo, pulmonary inflammation, pulmonary edema, ultrastructure changes of type II alveolar epithelial cells, MPO activity, total cells, neutrophils, macrophages, TNF-α, IL-6 and IL-1β in BALF, along with the expression of VCAM-1 and VEGF were dose-dependently attenuated by andrographolide. Meanwhile, in vitro, the expression of VCAM-1 and VEGF was also reduced by andrographolide. Moreover, our data showed that andrographolide significantly inhibited the ratios of phospho-IKKβ/total IKKβ, phospho-IκBα/total IκBα and phospho-NF-κB p65/total NF-κB p65, and NF-κB p65 DNA binding activities, both in vivo and in vitro., Conclusions: These results indicate that andrographolide dose-dependently suppressed the severity of LPS-induced ALI, more likely by virtue of andrographolide-mediated NF-κB inhibition at the level of IKKβ activation. These results suggest andrographolide may be considered as an effective and safe drug for the potential treatment of ALI.

Objective: To study myocardial and lung injuries initiated by hydrogen sulfide, and evaluate the role and effectiveness of normobaric and hyperbaric oxygen (HBO) treatment in rats., Methods: One hundred healthy male Wistar rats were randomly divided into five groups: A: Normal control group (no H2S); B: H2S-exposed group; C: H2S+33% oxygen treatment group; D: H2S+50% oxygen treatment group; E: H2S+HBO group. The rats in groups C, D and E were exposed to H2S in an exposure chamber (1 m3) and were made to inhale 300 ppm hydrogen sulfide for 60 min, and then they were subjected to normobaric or HBO therapy. Normobaric oxygen was at concentrations of 33% or 50%, HBO was for 100 min including compression and decompression; the rats in group A inhaled air under the same conditions. Blood was sampled immediately after the experiment for analysis of arterial blood gases, myocardial enzymes and cardiac troponin I. Lung was rapidly removed to be made into tissue homogenates and then cytochrome c oxidase activity was measured; myocardial and lung ultrastructural changes were observed by electron microscopy., Results: Arterial blood gases: partial pressure of O2 (mmHg) (Group A, 97.6 ± 8.38; B, 76.5 ± 6.95*; C, 83.2 ± 2.66*; D, 86.20 ± 10.75*; E, 93.50 ± 4.97: *p < 0.01 compared to group A) was significantly lower than that in group in all but HBO rats. For myocardial enzymes and cardiac troponin I every parameter in groups B and C was significantly higher than that in group A (p<0.01),with no difference in D and E. Cytochrome c oxidase activity (u/mg) of lung tissue was reduced compared to group A after all treatments (A, 1.76 ± 0.02; B, 0.36 ± 0.04; C, 0.50 ± 0.12; D, 0.56 ± 0.07; E, 0.68 ± 0.05 (A vs. B p < 0.01; B vs. C,D,E p < 0.05 or p < 0.01), with a graded effect of oxygen dose in C, D and E. Pathological changes: (1) Myocardium - Mitochondrial swelling and autolysis with blurred or broken cristae was observed in the myocardium of H2S-exposed group; in group E, mitochondrial structure was basically normal, and clear cristae were found. (2) Lung tissue - In H2S-exposed group, alveolar epithelial cells disappeared, vacuolization of the organelle occurred, nuclear membrane was irregular and marginal condensation of heterochromatin was present; nucleus showed relatively normal morphology in group E, although some vacuoles still persisted within them., Conclusions: HBO therapy can effectively improve arterial oxygen partial pressure, and significantly reduce myocardial damage, as well as potentially relieve lung injury in this model. Further work in humans appears warranted.