Glutamine inhibits inflammation, oxidative stress, and apoptosis and ameliorates hyperoxic lung injury

Glutamine (Gln) is the most widely acting and abundant amino acid in the body and has anti-inflammatory properties, regulates body metabolism, and improves immune function. However, the mechanism of Gln’s effect on hyperoxic lung injury in neonatal rats is unclear. Therefore, this work focused on examining Gln’s function in lung injury of newborn rats mediated by hyperoxia and the underlying mechanism. We examined body mass and ratio of wet-to-dry lung tissue weights of neonatal rats. Hematoxylin and eosin (HE) staining was performed to examine histopathological alterations of lung tissues. In addition, enzyme-linked immunoassay (ELISA) was conducted to measure pro-inflammatory cytokine levels within bronchoalveolar lavage fluid (BALF). Apoptosis of lung tissues was observed using TUNEL assay. Western blotting was performed for detecting endoplasmic reticulum stress (ERS)-associated protein levels. The results showed that Gln promoted body weight gain, significantly reduced pathological damage and oxidative stress in lung tissue, and improved lung function in neonatal rats. Gln reduced pro-inflammatory cytokine release as well as inflammatory cell production in BALF and inhibited apoptosis in lung tissue cells. Furthermore, we found that Gln could downregulate ERS-associated protein levels (GRP78, Caspase-12, CHOP) and inhibit c-Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) phosphorylation. These results in an animal model of bronchopulmonary dysplasia (BPD) suggest that Gln may have a therapeutic effect on BPD by reducing lung inflammation, oxidative stress, and apoptosis and improving lung function; its mechanism of action may be related to the inhibition of the IRE1α/JNK pathway. (AU)

Glutamine inhibits inflammation, oxidative stress, and apoptosis and ameliorates hyperoxic lung injury.

Glutamine (Gln) is the most widely acting and abundant amino acid in the body and has anti-inflammatory properties, regulates body metabolism, and improves immune function. However, the mechanism of Gln's effect on hyperoxic lung injury in neonatal rats is unclear. Therefore, this work focused on examining Gln's function in lung injury of newborn rats mediated by hyperoxia and the underlying mechanism. We examined body mass and ratio of wet-to-dry lung tissue weights of neonatal rats. Hematoxylin and eosin (HE) staining was performed to examine histopathological alterations of lung tissues. In addition, enzyme-linked immunoassay (ELISA) was conducted to measure pro-inflammatory cytokine levels within bronchoalveolar lavage fluid (BALF). Apoptosis of lung tissues was observed using TUNEL assay. Western blotting was performed for detecting endoplasmic reticulum stress (ERS)-associated protein levels. The results showed that Gln promoted body weight gain, significantly reduced pathological damage and oxidative stress in lung tissue, and improved lung function in neonatal rats. Gln reduced pro-inflammatory cytokine release as well as inflammatory cell production in BALF and inhibited apoptosis in lung tissue cells. Furthermore, we found that Gln could downregulate ERS-associated protein levels (GRP78, Caspase-12, CHOP) and inhibit c-Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) phosphorylation. These results in an animal model of bronchopulmonary dysplasia (BPD) suggest that Gln may have a therapeutic effect on BPD by reducing lung inflammation, oxidative stress, and apoptosis and improving lung function; its mechanism of action may be related to the inhibition of the IRE1α/JNK pathway.

The protective effects of glutamine against bronchopulmonary dysplasia are associated with MKP-1/MAPK/cPLA2 signalingmediated NF-kappaB pathway.

Glutamine is proven to have potential therapeutic effects on decreasing hyperoxia-induced acute pulmonary injury. The aim of this study is to investigate the effects and mechanism of glutamine on bronchopulmonary dysplasia (BPD) induced by hyperoxia in rat alveolar type II epithelial cells (AECIIs) RLE-6TN. Following hyperoxia induction and glutamine treatment, ROS levels were detected by DCFH-DA assay and TUNEL staining was performed to detect cell apoptosis. The levels of inflammatory indicators and expression of apoptosis-related proteins were detected through ELISA and Western blot, respectively. Besides, the expression of related proteins in mitogen-activated protein kinase phosphatase-1 (MKP-1)/mitogen-activated protein kinases (MAPK)/cytoplasmic phospholipase A2 (cPLA2) signaling was also detected by Western blot. To further analyze the role of MKP-1/MAPK/cPLA2 signaling, MKP-1 was silenced and anisomycin was used to treat cells, respectively. It was shown that glutamine significantly decreased inflammation, oxidative stress and apoptosis in hyperoxia-induced cells while MKP-1 interference and anisomycin were able to reverse these effects, suggesting that the protective effects of glutamine on BPD induced by hypoxia were related to MKP-1/MAPK/cPLA2 signaling. To sum up, glutamine protected against BPD by decreasing inflammation, oxidative stress and apoptosis via MKP-1/MAPK/cPLA2 signaling.

Glutamine ameliorates hyperoxia-induced hippocampal damage by attenuating inflammation and apoptosis via the MKP-1/MAPK signaling pathway in neonatal rats.

Glutamine (Gln) is an immunomodulatory protein that mediates oxidative stress, inflammation, and apoptosis, but has not been reported in the treatment of hyperoxia (Hyp)-induced brain injury. The aim of this study was to determine whether Gln could improve hyp-induced brain injury in neonatal rats to and later learning and memory dysfunction, and to explore its possible mechanisms. We prepared a model of neonatal rat brain injury caused by normobaric hyperoxia while administered with Gln for 7 days for evaluation. Learning memory function was assessed with the Morris water maze test. Histological analysis, protein expression analysis, oxidative stress and inflammation level analysis were performed using hippocampal tissue. Gln treatment significantly reduced brain tissue water content, oxidative stress levels, microglia activation and inflammatory factor expression, and attenuated tissue damage and apoptosis in the hippocampal region. Gln ameliorates hyp-induced learning, memory impairment in neonatal rats in water maze test. It also increased MKP-1 protein expression and decreased p-p38, p-ERK and p-JNK. Therefore, it is hypothesized that Gln may exert neuroprotective effects by increasing MKP-1 expression to negatively regulate MAPK signaling, with potential cognitive improvement in hyp-induced brain injury.

Insulin-like growth factor-1 reduces hyperoxia-induced lung inflammation and oxidative stress and inhibits cell apoptosis through PERK/eIF2α/ATF4/CHOP signaling.

Background: Insulin-like growth factor-1 (IGF-1), a member of the insulin family, has a high degree of homology with insulin and exhibits anti-inflammatory and anti-oxidative stress properties. However, the potential protective effect of IGF-1 on hyperoxia-induced lung injury remains unknown. In this study, we aimed to explore the effects and mechanism of action of IGF-1 in hyperoxia-induced lung injury in neonatal rats. Materials and Methods: Hematoxylin-eosin staining was used to observe pathological changes in lung tissue; transmission electron microscopy was used to examine the ultrastructure, and ELISA was used to detect the level of pro-inflammatory cytokines in bronchoalveolar lavage fluid. Further, malondialdehyde, glutathione, and superoxide dismutase activities in lung tissue were evaluated. TUNEL staining was used to detect cell apoptosis, and western blot analysis was used to detect the expression of Bax, Bcl-2, Caspase-3, p-PERK, p-eIF2α, ATF4, and CHOP in the lung tissue. Moreover, the wet/dry weight ratio of lung tissue was determined. Results: Intraperitoneal injection of IGF-1 effectively reduced lung tissue damage induced by hyperoxia; production of inflammatory cells and release of pro-inflammatory cytokines, oxidative stress, and cell apoptosis. Further, IGF-1 down-regulated the expression of ATF4, CHOP, and Bax/Bcl-2, and inhibited the phosphorylation of PERK and eIF2α. Conclusion: The results suggest that IGF-1 reduces hyperoxia-induced lung inflammation and oxidative stress in neonatal rats through the PERK/eIF2α/ATF4/CHOP signaling pathway and inhibits cell apoptosis.

Diagnostic Value of Neutrophil/lymphocyte Ratio and Platelet/lymphocyte Ratio in Premature Rupture of Membranes Complicated by Sepsis.

OBJECTIVE: To investigate the predictive value of neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) in premature rupture of membranes complicated by sepsis. STUDY DESIGN: A descriptive study. PLACE AND DURATION OF STUDY: Department of Paediatrics, Affiliated Hospital of Yanbian University, China, from January 2020 to June 2021. METHODOLOGY: Ninety-nine children with premature rupture of membranes and sepsis were included as group A and 99 children without sepsis were included as group B. Logistic regression analysis was used to analyse the risk factors for premature rupture of membranes complicated by sepsis. The diagnostic value of PLR and NLR in sepsis complicated by premature rupture of membranes was assessed by subject operating characteristic curve (ROC) curves. RESULTS: Univariate analysis showed significant differences between groups A and B in terms of mode of delivery, lymphocyte count, platelets, PLR and NLR (p <0.05). Logistic regression analysis showed that mode of delivery, platelets, PLR and NLR were independent risk factors for premature rupture of membranes complicated by sepsis (p <0.05). The ROC area for PLR was 0.781 (95% CI: 0.718-0.844, p <0.001), which was greater than that for NLR when premature rupture of membranes complicated by sepsis was predicted. When the PLR was >93.072, the sensitivity of predicting premature rupture of membranes complicated by sepsis was 67.7% and the specificity was 79.8%. CONCLUSION: PLR and NLR have a high predictive value for premature rupture of membranes complicated by sepsis. Among them, the predictive value of PLR was greater than NLR. KEY WORDS: Premature rupture of membranes, Sepsis, PLR, NLR, Subject operating characteristic curve (ROC).

Insulin-like growth factor-1: A potential target for bronchopulmonary dysplasia treatment (Review).

Bronchopulmonary dysplasia (BPD) is a common respiratory disorder among preterm infants, particularly low-birth-weight infants (LBWIs) and very-low-birth-weight infants (VLBWIs). Although BPD was first reported 50 years ago, no specific drugs or efficient measures are yet available for prevention or treatment. Insulin-like growth factor-1 (IGF-1) belongs to the insulin family. It promotes mitosis and stimulates cell proliferation and DNA synthesis, the primary factors involved in pulmonary development during the fetal and postnatal periods. Several studies have reported that IGF-1 exerts certain effects on BPD genesis and progression by regulating BPD-related biological processes. In addition, exogenous addition of IGF-1 can alleviate lung inflammation, cell apoptosis and eliminate alveolar development disorders in children with BPD. These findings suggest that IGF-1 could be a new target for treating BPD. Here, we summarize and analyze the definition, pathogenesis, and research status of BPD, as well as the pathogenesis of IGF-1 in BPD and the latest findings in related biological processes.

Pompe Disease Complicated with Appendicular Torsion: A Rare Concurrence.

Pompe disease, also known as Glycogen Storage Disease Type II, is a rare disorder of glucose metabolism caused by congenital acid alpha-glucosidase (GAA) deficiency. A large amount of glycogen accumulates in the lysosomes, causing these to swell and rupture. Its incidence is about 1 in 40,000 to 1 in 50,000 newborns. The main features are hypotonia and cardiomyopathy. Only a few clinical cases of Pompe disease have been reported, and appendicular torsion has rarely been observed. Herein, we report a case of Pompe disease combined with appendicular torsion, both of which were diagnosed on autopsy pathology. The clinical diagnosis of this disease is difficult in developing countries, and it is mostly misdiagnosed as other types of heart disease. Once the clinical symptoms worsen, most of them die within a short period. Therefore, screening for neonatal genetic metabolic diseases for early diagnosis and treatment should be carried out. Key Words: Glycogen storage disease type II, Metabolic disease, Enzyme replacement therapy, Neonatal screening.

Platelet-to-Lymphocyte and Neutrophil-to-Lymphocyte Ratio as Predictive Biomarkers for Early-onset Neonatal Sepsis.

OBJECTIVE: To determine the predictive significance of platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) in early-onset neonatal sepsis (EONS). STUDY DESIGN: A descriptive study. PLACE AND DURATION OF STUDY: The Neonatal Intensive Care Unit (NICU), Affiliated Hospital of Yanbian University, Jilin, China, from January 2018 to January 2020. METHODOLOGY: Of the total 124 children, 74 children with EONS were enrolled in group A and 50 children without infection-related diseases were enrolled in group B (control). The EONS risk factors were evaluated by logistic regression. Besides, the PLR and NLR diagnostic performances in EONS were evaluated by plotting the receiving operating characteristic (ROC) curves. RESULTS: In the univariate analysis, the differences for platelet count, lymphocyte number, neutrophil number, NLR, and PLR, between group A and group B were of statistical significance (p = 0.02, 0.021, <0.001, <0.001, and <0.001 respectively). As suggested by logistic regression, PLR and NLR were identified as the factors to independently predict the risk of EONS (p = 0.012, and 0.003, respectively). In addition, the value of area under the ROC curve (AUC) of NLR in predicting EONS was 0.788 (95% CI: 0.708-0.868; p <0.001), which was greater than that of PLR. At the NLR value of ≥3.169, the sensitivity of predicting EONS was 77%, and the specificity was 78%. CONCLUSION: Peripheral blood NLR and PLR have high predictive value for EONS. The predictive value of NLR as a biomarker for EONS evaluation was greater than that of PLR. Key Words: Neonatal sepsis, Logistic models, ROC curve, Blood cell count.

[Protective effect of prostaglandin E1 against brain injury induced by hyperoxia in neonatal rats].

OBJECTIVE: To investigate the protective effect of prostaglandin E1 (PGE-1) against brain injury induced by hyperoxia in neonatal rats and observe the changes in the expression of glucose-regulated protein 78 (GRP78) and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), and to provide a theoretical basis for the clinical application of PGE-1 in the treatment of neonatal brain injury induced by hyperoxia. METHODS: Sixty neonatal Wistar rats were randomly divided into air control group, hyperoxic brain injury model group, and hyperoxic brain injury+PGE-1 group. All rats except those in the air control group were treated to establish a hyperoxic brain injury model. From the first day of modeling, the rats in the hyperoxia brain injury+PGE-1 group were intraperitoneally injected with PGE-1 2 µg/kg daily for 7 consecutive days, while the other two groups were treated with normal saline instead. The water content of brain tissue was measured; the pathological changes of brain tissue were evaluated by hematoxylin-eosin staining; the apoptosis of brain cells was assessed by nuclear staining combined with TUNEL staining; the protein expression of GRP78 and CHOP in brain tissue was measured by Western blot. RESULTS: The water content of brain tissue in the hyperoxic brain injury model group was significantly higher than that in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the water content of brain tissue in the hyperoxic brain injury+PGE-1 group was significantly higher than that in the air control group (P<0.05). The pathological section of brain tissue showed inflammatory cell infiltration and mild cerebrovascular edema in the brain parenchyma in the hyperoxic brain injury model group; the periparenchymal inflammation and edema in the hyperoxic brain injury+PGE-1 group were milder than those in the hyperoxic brain injury model group. The apoptosis index of brain tissue in the hyperoxic brain injury model group was significantly higher than that in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the apoptosis index of brain tissue in the hyperoxic brain injury+PGE-1 group was significantly higher than that in the air control group (P<0.05). The protein expression of GRP78 and CHOP in brain tissue was significantly higher in the hyperoxic brain injury model group than in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the protein expression of GRP78 and CHOP was significantly higher in the hyperoxic brain injury+PGE-1 group than in the air control group (P<0.05). CONCLUSIONS: PGE-1 has a protective effect against hyperoxia-induced brain injury in neonatal rats, which may be related to the inhibition of cell apoptosis by down-regulating the expression of GRP78 and CHOP.

[Glutamine inhibits the inflammation in preterm rats with lung injury induced by hyperoxia and its mechanism].

Objective To investigate the effect of glutamine on the preterm hyperoxia-induced lung inflammation injury of rat models. Methods The rat model of lung injury induced by preterm hyperoxia was prepared and treated with glutamine. Diff-Quik staining was used to detect the aggregation of inflammatory cells in the bronchoalveolar lavage fluid (BALF), and HE staining was used to observe the inflammation of lung tissues. TUNEL staining was performed to detect the cell apoptosis in the lung tissues, and ELISA to test the levels of IL-1ß and tumor necrosis factor α (TNF-α) in BALF. The phosphorylation of mitogen-activated protein kinase phosphatase-1 (MKP-1), mitogen-activated protein kinase (MAPK) and cytosolic phospholipase A2 (cPLA2) in the lung tissues were detected by Western blotting. Results Glutamine alleviated lung inflammation response and cell apoptosis, and reduced the levels of IL-1ß and TNF-α in the inflammatory lung tissues of premature rats. Meanwhile, glutamine promoted the phosphorylation of MKP-1, and inhibited the activation of MAPK and cPLA2. Conclusion Glutamine inhibits pulmonary inflammation in preterm hyperoxia-induced lung injury rat models via regulating MKP-1/MAPK signaling pathway.

Alteration of TGF-ß-ALK-Smad signaling in hyperoxia-induced bronchopulmonary dysplasia model of newborn rats.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a main chronic lung disease commonly occurs in preterm infants. BPD is characterized by impaired alveolarization and vascularization of the developing lung. Transforming growth factor-ß (TGF-ß) signaling pathway is known to play an important role during lung vascular development. In the present study, we examined whether the regulation of TGF-ß-ALK-Smad signaling pathway influence on the disruption of pulmonary vascular development in newborn rats as hyperoxia-induced BPD model. MATERIALS AND METHODS: Newborn rats were continuously exposed to 21% or 85% O2 for 7 days, and subsequently kept in normoxic condition for another 14 days. Lung tissues harvested at each time point were evaluated for the expression of TGF-ß1, ALK1, ALK5, phosphorylated Smad1/5, phosphorylated Smad2/3, VEGF, and endoglin, as accessed by both biochemical and immunohistological analyses. RESULTS: Double-fluorescence immunohistochemical staining indicated these molecules were mainly expressed in pulmonary endothelial cells. The expression of TGF-ß1 and ALK5 mRNA and protein were significantly increased in D5 hyperoxia group, while that of ALK1 mRNA and protein were significantly decreased. The level of phosphorylated Smad1/5 was significantly decreased in D7 hyperoxia group, whereas that of phosphorylated Smad2/3 was oppositely increased. In addition, the expression of vascular endothelial growth factor (VEGF) mRNA was increased at D1 with subsequent decrease in D7 hyperoxia group. There was no significantly difference in endoglin expression in entire experimental period. CONCLUSION: These results indicate that exposure to hyperoxia altered the balance between TGF-ß-ALK1-Smad1/5 and TGF-ß-ALK5-Smad2/3 pathways in pulmonary endothelial cells, which may ultimately lead to the development of BPD.

[Effect of insulin-like growth factor-1 on hyperoxia-induced apoptosis in A549 cells].

OBJECTIVE: To investigate the effect of insulin-like growth factor-1 (IGF-1), which can promote cell differentiation and inhibit cell apoptosis, on hyperoxia-induced apoptosis in A549 cells and its anti-apoptotic mechanism. METHODS: A549 cells were sub-cultured, exposed to hyperoxic conditions and were then treated with different concentrations of IGF-1 (1, 10, and 100 ng/mL) for 48 hours. Cell viability was measured by MTT assay. Cell apoptosis was evaluated by Annexin V-FITC/PI double-staining flow cytometry. Expression levels of Bax and Bcl-2 were measured by flow cytometry. RESULTS: The middle-dose and high-dose IGF-1 intervention groups had higher cell viabilities than the hyperoxic exposure group [(64±3)% and (88±4)% vs (51±3)%; P<0.05]. Compared with the air control group, the hyperoxic exposure group had a significantly higher apoptotic rate [(38.3±5.4)% vs (2.4±0.9)%; P<0.05], a significantly lower expression level of Bcl-2 [(72±5)% vs (91±4)%; P<0.05], and a significantly higher expression level of Bax [(54±6)% vs (3±2)%; P<0.05]. Compared with the hyperoxic exposure group, the low-dose, middle-dose, and high-dose IGF-1 intervention groups had significantly lower apoptotic rates [(16.1±4.7)%, (9.2±2.8)%, and (6.9±2.5)% vs (38.3±5.4)%; P<0.05], significantly higher expression level of Bcl-2 [(79±4)%, (94±4)%, and (100±5)% vs (72±5)%; P<0.05], and significantly lower expression level of Bax [(26±4)%, （5±2)%, and (4±2)% vs (54±6)%; P<0.05]. CONCLUSIONS: Hyperoxia significantly inhibits proliferation and promotes apoptosis in A549 cells. IGF-1 may promote cell proliferation and inhibit hyperoxia-induced apoptosis in A549 cells by regulating the expression of Bcl-2 and Bax.

[Levels of nerve growth factor and interleukin-4 in the induced sputum of children with cough variant asthma].

OBJECTIVE: To examine the levels of nerve growth factor (NGF) and interleukin-4 (IL-4) in the induced sputum of children with cough variant asthma (CVA), with the aim of studying the roles of NGF and IL-4 in childhood CVA. METHODS: Thirty-four children with CVA were enrolled in this study. Twenty healthy children were used as a normal control group. The induced sputum was separated into supernatant and cells. Hematoxylin and eosin staining was used to count differential cells. The expression of NGF and IL-4 in supernatant was measured using ELISA. The mRNA expression of NGF and IL-4 in cells was determined by Real-time PCR analysis. RESULTS: The percentage of eosinophils in the CVA group was significantly higher than in the control group [(13.4±3.6)% vs (2.6±1.7)%; P<0.01]. The expression of NGF and IL-4 protein and mRNA in induced sputum was significantly higher in the CVA group than in the control group (P<0.05). The expression of NGF and IL-4 protein and mRNA was positively correlated with the percentage of eosinophils (P<0.01). The expression of NGF and IL-4 protein and mRNA in induced sputum was significantly reduced in the CVA group after treatment (P<0.05). CONCLUSIONS: Eosinophils infiltration and increased expression of NGF and IL-4 play key roles in the development of childhood CVA, suggesting that they may be useful in the diagnosis and treatment of childhood CVA.

Epidemiological investigation of Kawasaki disease in Jilin province of China from 2000 to 2008.

OBJECTIVE: To investigate the epidemiological characteristics of Kawasaki disease in Jilin province of China and explore its clinical features. METHODS: The medical records of children with Kawasaki disease hospitalised in the First Affiliated Hospital of Jilin University and Yanbian University between January, 2000 and December, 2008 were retrospectively analysed. RESULTS: A total of 735 children with Kawasaki disease were enrolled in this study with 483 boys and 252 girls. The ratio of male to female was 1.92:1. The ages of the children at onset varied from 51 days to 12 years with a mean age of 2.8 years. The children under the age of 5 years accounted for 79.5%, but most children were 2-3 years old. Kawasaki disease occurred all the year and more frequently in both the ending of spring and the beginning of summer. Fever was the most common clinical feature and enlarged cervical lymph nodes were the smallest clinical feature. A cardiovascular lesion was found in 41.4% of these children, in whom coronary artery dilatation was the most common (26.97%). A total of 117 (18.2%) of 643 children (87.5%) receiving intravenous immunoglobulin had a non-response to gamma globulin. Of the 117 children, 66 (56.4%) had cardiovascular lesion. Kawasaki disease recurred in 19 children (2.6%). CONCLUSION: The incidence of Kawasaki disease in Jilin province has shown an increasing tendency. The age at onset is slightly higher than that described in other reports. Kawasaki disease is the most common in both the ending of spring and the beginning of summer, and the second incidence peak occurs in autumn.

[Effects of diesel exhaust particles inhalation on immediate reaction in asthma rats].

OBJECTIVE: The role of air pollution on asthma can not be ignored, diesel exhaust particles (DEP) in the air is one of the most important pollutants. This study aimed to investigate the effect and mechanism of DEP inhaled on immediate reaction in the asthma rats. METHOD: Sixty male Wistar rats of "Clean" grade, 6 - 7 week-old, with an average weight of (140 +/- 20) g were used in this study. The rats were randomly divided into 6 groups, 10 in each. Group A was treated with normal saline attack as a negative control, Group B with ovalbumin attack as a positive control. After ovalbumin attack, groups C, D, E, F continued to inhale DEP for 1 week, 2 weeks, 3 weeks and 4 weeks, respectively. The concentration of DEP was 200 microg/ml, the animals were subjected to inhalation of ultrasound nebulized DEP for 30 min per day. One week after all the attacks were concluded, Group A was stimulated with normal saline for 30 min, other groups were stimulated with ovalbumin. Then the airway resistance was determined with multi-channel signal acquisition and processing system and compared. The changes in neutrophils, eosinophils, and other inflammatory cells of BALF and the pathological changes in lung tissue, including epithelial cells loss, the inflammatory cells infiltration around the airway, basement membrane fibrosis, goblet cell hyperplasia etc. were observed. The concentration of IL-5 and gamma-interferon in the lung tissues, and the changes of serum IgE etc. were determined. RESULT: Airway resistance values of group A, B, C, D, E, F after ovalbumin excitation for 30 min were (3.56 +/- 0.21), (7.06 +/- 0.63), (6.46 +/- 0.38), (7.47 +/- 0.33), (8.87 +/- 0.61), (11.00 +/- 0.69) cm H2O/(ml.s). No airway hyperresponsiveness occurred in group A, while Groups B, C, D, E, F had higher airway resistance than group A, group E and F had higher airway resistance than that of group B, the differences were statistically significant. And the airway resistance was different in each group among 0 min, 10 min, 20 min and 30 min (F = 160.646, 148.901, 162.204, 156.186, P < 0.01 for both). The time of DEP inhalation and the airway resistance was positively correlated (r = 0.948, P < 0.01); IgE concentrations of the serum between groups B, C, D, E, F was not significantly different (P > 0.05), but higher than that of group A (F = 2.639, P < 0.01). The infiltrated inflammatory cells included eosinophils and lymphocytes, etc. The percentages of neutrophil(%) were (4.3 +/- 2.0), (9.7 +/- 5.2), (10.3 +/- 5.6), (13.0 +/- 5.2), (42.6 +/- 18.3), (55.3 +/- 6.9). The groups E and F had higher percentage than Group A and Group B (F = 114.226, P < 0.01). The percentages of eosinophils(%) were 0, (11.9 +/- 3.8), (15.8 +/- 6.3), (13.0 +/- 4.9), (21.1 +/- 5.6), (27.1 +/- 4.8). The difference between Groups B, C, D, E, F and Group A was statistically significant. There was significant difference between groups C, D, E, F and group B (F = 46.462, P < 0.05); Lung tissue biopsy in group A showed that the epithelial cells were intact, no inflammatory cells infiltrations were found around the airways, instead, mainly ciliated columnar epithelial cells and only a small number of goblet cells were seen without basement membrane fibrosis. With the inhalation of DEP, the epithelial cells showed gradual necrosis, disruption and loss, goblet cells showed hyperplasia, and infiltrations with inflammatory cells were seen around the airway. In the lung tissue, concentrations of IL-5 in group B, C, and E were (12.8 +/- 2.8), (17.1 +/- 5.2), (18.6 +/- 4.2) pg/mg, the difference between groups C, E and group B was statistically significant (F = 4.236, P < 0.01), the difference in gamma-interferon concentration among all groups was not statistically significance (F = 1.185, P > 0.05). CONCLUSION: DEP inhalation increased the airway responsiveness of asthma rats in immediate reaction, promoted the lung epithelial cell loss, inflammatory cell infiltration, basement membrane fibrosis and goblet cell hyperplasia.

[Effects of recombinant human insulin-like growth factor-1 on the expression of Clara cell secretory protein in lung of hyperoxia-exposed newborn rats].

OBJECTIVE: The development of neonatology and the availability of pulmonary surfactant have been helpful in effective reduction of the mortality of very low birth weight infants at the expense of an increasing number of survivors with bronchopulmonary dysplasia (BPD) caused by lung immaturity. BPD is a common syndrome in newborns, especially in preterm infants, when treated with hyperoxia and mechanical ventilation. Unfortunately, there have been no effective measure for the prevention and treatment of BPD. The purpose of this study was to investigate the influence of recombinant human insulin-like growth factor-1 (rh-IGF-1) on cell apoptosis and Clara cell secretory protein (CCSP) expression during the lung injury induced by hyperoxia, so as to assess its effect on the inflammatory lung injury and its developmental repair. METHODS: Eighty full term neonatal Wistar rats under the same condition were divided randomly into four groups on the second day after birth. Group I was air control, group II was exposed to hyperoxia, group III air + rh-IGF-1, and group IV was treated with hyperoxia + rh-IGF-1. The pups in the control group were kept in room air, while pups in hyperoxia group were kept in a Plexiglas chamber and exposed to over 85% oxygen. Pups in group III were under the same raising condition except for exposure to room air and treated with intraperitoneal injection of rh-IGF-1 (1 microg/Kg) everyday from the third day. Pups in group IV were treated with intraperitoneal injection of rh-IGF-1 (1 microg/Kg) everyday from the third day of exposure to hyperoxia. Lung tissue sections of the neonatal rats were stained with hematoxylin and eosin (HE) after 7 d of hyperoxia exposure, expression of CCSP was examined by immunohistochemical method, and apoptotic cell index of lung tissue was calculated by using TUNEL method. RESULTS: It was observed from immunohistochemical examination that positive staining of CCSP was distributed mainly in distal and respiratory bronchioles. The percentage of Clara cells in distal and respiratory bronchioles epithelium decreased in hyperoxia group (32.17 +/- 3.19)% compared to that in air control group (68.32 +/- 2.04)%, P < 0.01. Statistically significant differences were found in intensity of positiveness of Clara cells between hyperoxia (29.45 +/- 5.56) and air control group (42.37 +/- 3.24), P < 0.01. TUNEL assay showed that most apoptotic cells were alveolar and bronchial epithelial cells. The apoptotic index increased significantly in the hyperoxia group (55.77 +/- 6.09)% compared to the air control group (16.41 +/- 4.01)%, (P < 0.01). The positive rate (52.98 +/- 2.68)% of Clara cells and the expression (41.22 +/- 6.36) of CCSP in hyperoxia + rh-IGF-1 group increased significantly when compared with hyperoxia group, and the differences between these two group were also statistically significant (P < 0.01). The apoptotic index increased significantly in the hyperoxia + rh-IGF-1 group (27.98 +/- 3.09)% compared to the hyperoxia group (P < 0.01). CONCLUSIONS: Hyperoxia exposure can promote the pneumocyte apoptosis and inhibit the expression of CCSP. Rh-IGF-1 can remove the block of the formation of lung alveoli, increase the secretion of CCSP, mitigate inflammatory responses in airway and alleviate lung injury via pneumocyte apoptosis. Therefore, the results of this study provide a theoretic and experimental evidence for clinical application of rh-IGF-1 in prevention and treatment of BPD.