Attenuating heat-induced acute lung inflammation and injury by dextromethorphan in rats

Dextromethorphan (DM) has been shown to protect against endotoxic shock in mice. Heatstroke resembles sepsis in many respects. The objective of this study was to examine the heat-induced acute lung inflammation and injury in rats with or without DM, and for comparison with those of the rats with MK-801 (an N-methyl-D-aspartate receptor antagonist), SA4503 (a sigma-1 receptor agonist), or fluoxetine (a serotonin reuptake inhibitor). Heatstroke was induced by exposing the anesthetized rats to heat stress (43°C for 68 min). At 68 minutes after start of heat stress, animals treated with vehicle medium, DM (10-30 mg/kg of body weight, intramuscular), MK-801 (1 mg/kg of body weight, intraperitoneal), SA4503 (1 mg/kg of body weight, intraperitoneal), or fluoxetine (5 mg/kg of body weight, intraperitoneal) were allowed to recover at room temperature (26°C). As compared with vehicle-treated heatstroke rats (25-31 min; n = 8), DM (30 mg/kg)-treated heatstroke rats and MK-801 (1 mg/kg)-treated heatstroke rats had significantly greater survival time (193-209 min [n = 7] and 121-133 min [n = 8], respectively). However, the survival times for the SA4503-treated heatstroke rats (28-34 min; n = 8) or the fluoxetine-treated heatstroke rats (20-26 min; n = 8) were not significantly different from the vehicle-treated heatstroke rats. DM treatment significantly: (1) reduced acute lung injury, including edema, neutrophils infiltration, and hemorrhage scores; (2) decreased acute pleurisy; and (3) decreased bronchoalveolar fluid levels of the proinflammatory cytokines, and ischemia and oxidative damage markers during heatstroke. Our results indicate that DM therapy may improve outcomes of heatstroke in rats by antagonizing the N-methyl-D-aspartate receptors.     

Large dose ketamine inhibits lipopolysaccharide-induced acute lung injury in rats

Background: Sepsis is associated with the highest risk of progression to acute lung injury or the acute respiratory distress syndrome. Ketamine has been advocated for anesthesia in endotoxemic and other severely ill patients because it is a cardiovascular stimulant. Our study was designed to investigate the effect of ketamine on the endotoxin-induced acute lung injury in vivo.Materials and methods: Adult male Wistar rats were randomly divided into 6 groups: saline controls; rats challenged with endotoxin (5 mg/kg) and treated with saline; challenged with endotoxin (5 mg/kg) and treated with ketamine (0.5 mg/kg); challenged with endotoxin (5 mg/kg) and treated with ketamine (5 mg/kg); challenged with endotoxin (5 mg/kg) and treated with ketamine (50 mg/kg); saline injected and treated with ketamine (50 mg/kg). TNF-, IL-6 and NF-kappa B were investigated in the tissues of the lung after 2 h. Myeloperoxidase (MPO) activity and wet/dry weight ratio were investigated 6 h later.Results: We demonstrated that intravenous administration of endotoxin could provoke significant lung injury, which was characterized by increase of MPO activity and wet/dry weight ratio, TNF- and IL-6 expression and NF-kappa B activation. Ketamine (5, 50 mg/kg) inhibited endotoxin-induced NF-kappa B activation. Ketamine only at a dose of 50 mg/kg inhibited TNF- and IL-6 production, and decreased MPO activity and wet/dry weight ratio after endotoxin challenge.Conclusions: Ketamine, only at a supra-anesthetic dosage, could inhibit endotoxin-induced pulmonary inflammation in vivo.Received 27 August 2004; returned for revision 11 November 2004; accepted by A. Falus 15 November 2004     

Regional pulmonary inflammation in an endotoxemic ovine acute lung injury model

The regional distribution of inflammation during acute lung injury (ALI) is not well known. In an ovine ALI model we studied regional alveolar inflammation, surfactant composition, and CT-derived regional specific volume change (sVol) and specific compliance (sC). 18 ventilated adult sheep received IV lipopolysaccharide (LPS) until severe ALI was achieved. Blood and bronchoalveolar lavage (BAL) samples from apical and basal lung regions were obtained at baseline and injury time points, for analysis of cytokines (IL-6, IL-1β), BAL protein and surfactant composition. Whole lung CT images were obtained in 4 additional sheep. BAL protein and IL-1β were significantly higher in injured apical vs. basal regions. No significant regional surfactant composition changes were observed. Baseline sVol and sC were lower in apex vs. base; ALI enhanced this cranio-caudal difference, reaching statistical significance only for sC. This study suggests that apical lung regions show greater inflammation than basal ones during IV LPS-induced ALI which may relate to differences in regional mechanical events.     

褪黑素预处理对抗油酸引起的大鼠急性肺损伤

目的：评估褪黑素预处理对油酸引起的大鼠急性肺损伤的拮抗作用。方法：24只大鼠随机分为生理盐水组、油酸组和褪黑素预处理组3组，检测大鼠肺泡灌洗蛋白、肺的湿干比重、丙二醛、超氧化物岐化酶水平，并进行肺的病理组织学检查。结果：（1）静脉注射0.15 mL/kg油酸引起肺泡灌洗蛋白、肺的湿干比重显著增高（P<0.01），病理组织学检查发现有肺出血、肺水肿、肺泡间隔增厚以及肺泡腔出现炎性细胞，导致严重的急性肺损伤；（2）提前60 min腹腔注射20 mg/kg褪黑素明显减轻上述的症状，与丙二醛的降低（P<0.01）和超氧化物岐化酶的升高（P<0.01）相一致。结论：褪黑素预处理可通过清除和防止自由基的形成，进一步降低肺泡毛细血管膜通透性的增加，从而减轻油酸引起的大鼠急性肺损伤。提示褪黑素可能在急性肺损伤的防治中是有效的。     

Cathepsin B and D activity in alveolar macrophages from rats with pulmonary granulomatous inflammation or acute lung injury

Cathepsin B and D activity was determined using specific synthetic substrates in alveolar macrophages (AMs) obtained from Sprague-Dawley rats with experimentally induced pulmonary granulomatous inflammation. Increased cathepsin B activity was found 4 days after intravenous injection of complete Freund's adjuvant (CFA), but not after injection of live bacillus Calmette-Guérin organisms (BCG), indicating that the enzyme response was unrelated to the subsequent development of granulomatous inflammation. Findings of comparable increases in enzyme activity following injection of mineral oil (MO) indicate that the response to CFA was due to the oil component. Significantly, oleic acid (OA), a natural fatty acid, did not stimulate enzyme activity although the agent, like MO, caused acute lung injury as assessed by¹²⁵I albumin uptake. At 7 and 28 days following injection of CFA, cathepsin B levels in AMs were the same as those in animals given normal saline (NS), although bronchoalveolar lavage (BAL) samples still contained increased numbers of AMs, and cells obtained at 28 days phagocytosed more polystyrene microspheres. Cathepsin D activity did not increase 4 days after injection of CFA or BCG+CFA; at 28 days following injection of BCG+CFA activity was significantly decreased as compared to animals given NS. The data reveal a differential response of two lysosomal enzymes during the early phases of granulomatous inflammation.     

火把花根片抑制大鼠急性肺损伤黏附分子表达

目的： 探讨火把花根片对大鼠急性肺损伤（ALI）黏附分子表达的影响。方法: 经尾静脉注射油酸建立ALI模型并分为ALI组、火把花根＋ALI组和对照组。用流式细胞术和免疫组化SP法测定外周血中性粒细胞（PMN）和单核细胞黏附分子CD11a、CD11b和CD18的表达及肺组织ICAM-1活性，检测肺湿/干重比(W/D)、肺通透指数(LPI)、支气管肺泡灌洗液(BALF)中白细胞(WBC)数和活化PMN比值。结果: ALI组PMN和单核细胞表面的CD11a、CD11b、CD18和肺组织ICAM-1表达水平高于对照组(P<0.01) ，火把花根＋ALI组上述指标显著低于ALI组 (P<0.01)。肺W/D比 、LPI、BALF中WBC计数和活化PMN比值显著低于ALI组 (P<0.01)。结论: PMN和单核细胞黏附分子CD11a、CD11b、CD18和肺组织ICAM-1的表达上调，参与ALI的病理发展过程。火把花根片对ALI具有拮抗作用。     

Erythropoietin attenuates hyperoxia-induced lung injury by down-modulating inflammation in neonatal rats

This study was done to determine whether recombinant human erythropoietin (rhEPO) treatment could attenuate hyperoxia-induced lung injury, and if so, whether this protective effect is mediated by the down-modulation of inflammation in neonatal rats. Newborn Sprague Dawley rat pups were subjected to 14 days of hyperoxia (>95% oxygen) within 10 hr after birth. Treatment with rhEPO significantly attenuated the mortality and reduced body weight gain caused by hyperoxia. With rhEPO treatment, given 3 unit/gm intraperitoneally at 4th, 5th, and 6th postnatal day, hyperoxia- induced alterations in lung pathology such as decreased radial alveolar count, increased mean linear intercept, and fibrosis were significantly improved, and the inflammatory changes such as myeloperoxidase activity and tumor necrosis factor-alpha expression were also significantly attenuated. In summary, rhEPO treatment significantly attenuated hyperoxia-induced lung injury by down-modulating the inflammatory responses in neonatal rats.     

肺血管内皮细胞在大鼠急性肺损伤发生中的作用

目的:观察肺血管内皮细胞受损在大鼠急性肺损伤发病中的作用及地塞米松的影响。方法:给Wistar大鼠静脉注射脂多糖(LPS5mg/kgBW)复制急性肺损伤模型。采用ELISA、放射免疫、原位杂交等多种方法测定肺组织ICAM-1mRNA表达、iNOS活性、血中TNF-α、NO₂^-/NO₃^-、ACE含量及肺血管通透性、肺泡灌洗液中细胞数、蛋白含量等的变化。结果:注射LPS后,肺血管ICAM-1mRNA表达增加,从1h开始至24h达高峰。肺组织匀浆iNOS活性升高、肺血管通透性升高、肺泡灌洗液中中性粒细胞数量增加,巨噬细胞数量减少、蛋白含量增加,血中TNF-α、NO₂^-/NO₃^-含量升高而ACE含量下降等变化多在注LPS后2h明显。预先给予地塞米松对上述多种指标的变化有明显缓解作用。结论:提示LPS通过损伤肺血管内皮细胞导致急性肺损伤,地塞米松对其有一定保护作用。     

Quercetin protects against lipopolysaccharide-induced acute lung injury in rats through suppression of inflammation and oxidative stress

Introduction

Acute lung injury (ALI) is an acute inflammatory disease characterized by excess production of inflammatory factors in lung tissue. Quercetin, a herbal flavonoid, exhibits anti-inflammatory and anti-oxidative properties. This study was performed to assess the effects of quercetin on lipopolysaccharide (LPS)-induced ALI.

Material and methods

Sprague-Dawley rats were randomly divided into 3 groups: the control group (saline alone), the LPS group challenged with LPS (Escherichia coli 026:B6; 100 µg/kg), and the quercetin group pretreated with quercetin (50 mg/kg, by gavage) 1 h before LPS challenge. Bronchoalveolar lavage fluid (BALF) samples and lung tissues were collected 6 h after LPS administration. Histopathological and biochemical parameters were measured.

Results

The LPS treatment led to increased alveolar wall thickening and cellular infiltration in the lung, which was markedly prevented by quercetin pretreatment. Moreover, quercetin significantly (p < 0.05) attenuated the increase in the BALF protein level and neutrophil count and lung wet/dry weight ratio and myeloperoxidase activity in LPS-challenged rats. The LPS exposure evoked a 4- to 5-fold rise in BALF levels of tumor necrosis factor-α and interleukin-6, which was significantly (p < 0.05) counteracted by quercetin pretreatment. Additionally, quercetin significantly (p < 0.05) suppressed the malondialdehyde level and increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in the lung of LPS-treated rats.

Conclusions

Quercetin pretreatment effectively ameliorates LPS-induced ALI, largely through suppression of inflammation and oxidative stress, and may thus have therapeutic potential in the prevention of this disease.     

Granulocyte colony-stimulating factor exacerbates the acute lung injury and pulmonary fibrosis induced by intratracheal administration of bleomycin in rats

We investigated the effects of granulocyte colony-stimulating factor (G-CSF) on lung injury induced by intratracheal administration of bleomycin (BLM, 2 mg/200 micro1) in rats. In experiment 1, G-CSF (10, 30 and 100 microg/kg/day, s.c.) was administered to rats treated with BLM or saline for 7 days starting immediately after BLM administration. In rats receiving G-CSF alone, a large number of neutrophils were noted in the pulmonary capillaries, although there were no lung lesions. In rats receiving BLM alone, diffuse alveolar damage was observed. The administration of G-CSF to BLM-treated rats increased the total lung lesion per unit of pulmonary parenchyma (total lung lesion %) along with increases in the peripheral neutrophil count and the number of neutrophils infiltrating in the pulmonary lesion in a dose-dependent fashion. In experiment 2, 100 microg/kg/day of G-CSF was administered to rats treated with BLM or saline for up to 28 days starting immediately after BLM administration. The administration of 100 microg/kg/day of G-CSF to BLM-treated rats showed no effects at 14 days but it increased the lung lesion % and the score of lung fibrosis along with the increase in the number of neutrophils infiltrating in the pulmonary lesion at 28 days. These findings suggest that G-CSF administration to BLM-treated rats influenced and exacerbated the BLM-induced acute lung injury, and also exacerbated pulmonary fibrosis in a dose-dependent fashion. The exacerbation of lung injury coincided with the marked increase in the peripheral neutrophil count and the number of neutrophils infiltrating in the pulmonary lesion.     

Increased carrageenan-induced acute lung inflammation in old rats

Ageing is associated with increased susceptibility to lung infections and delayed resolution of pulmonary infiltrates. The purpose of this study was to investigate the effect of age on the onset of carrageenan-induced lung inflammation. When compared with carrageenan-treated young rats (3 months old), old rats (>18 months old) exhibited a preponderance of pleural exudation and polymorphonuclear cell infiltration. Lung myeloperoxidase activity, an index of neutrophil infiltration and activation, was significantly increased in old rats in comparison with young rats. Consistent with the biochemical markers of inflammation, increased lung damage, as assessed by nitrosative stress and lipid peroxidation, was observed in carrageenan-treated old rats. In the lung exudate obtained from old rats, a significant reduction in interleukin-10 (IL-10) was observed, while similar expression of monocyte chemotactic protein-1 was induced, suggesting that a decrease in IL-10 rather than increased chemotaxis may account for the preponderance of the inflammatory cellular infiltrate in old rats. Similar to the in vivo situation, freshly isolated alveolar macrophages obtained from old rats produced less IL-10. This defective IL-10 production could be explained by a reduction in the cAMP-dependent signalling pathway, which mediates IL-10 production. Indeed, we found decreased cAMP-responsive element binding protein (CREB) and phosphorous-CREB (P-CREB) expression in old rats, which may account for reduced IL-10 production in old rats.     

TLR4 activity is required in the resolution of pulmonary inflammation and fibrosis after acute and chronic lung injury

Pulmonary fibrosis is an inflammation-driven lung disease with a poor prognosis and no cure. Here we report that basal toll-like receptor 4 (TLR4) activity is critical for the resolution of acute and chronic inflammation and pulmonary fibrosis in mouse models of lung injury. We found that genetic or pharmacologic inhibition of TLR4 exacerbates bleomycin-induced pulmonary inflammation, fibrosis, dysfunction, and animal death through promoting formation of an immunosuppressive tissue microenvironment and attenuating autophagy-associated degradation of collagen and cell death in the fibrotic lung tissues. In contrast, pharmacologic activation of TLR4 resulted in a quick resolution of acute inflammation, reversed the established pulmonary fibrosis, improved lung function, and rescued mice from death. Similarly, blocking TLR4 impaired the resolution of silica-induced chronic inflammation and fibrosis. Importantly, altering autophagic activity could reverse the TLR4-regulated lung inflammation, fibrosis, dysfunction, and animal death. Rapamycin, an autophagy activator, reversed the effects of TLR4 antagonism. In contrast, inhibition of autophagy by 3-methyladenine reversed the proresolving and antifibrotic roles of TLR4 agonists and increased animal death. These results not only highlight a pivotal role for TLR4-mediated basal immunity, particularly autophagic activity, in the proresolution of inflammation and fibrosis after chemical-induced lung injury but also provide proof for the concept for activating TLR4 signaling, particularly TLR4-mediated autophagy, as a novel therapeutic strategy against chronic fibroproliferative diseases that are unresponsive to current therapy.     

Carbon monoxide inhibits hypoxic pulmonary vasoconstriction in rats by a cGMP-independent mechanism

 Hypoxia activates erythropoietin-producing cells, chemoreceptor cells of the carotid body and pulmonary artery smooth muscle cells (PSMC) with a comparable arterial PO₂ threshold of some 70 mmHg. The inhibition by CO of the hypoxic responses in the two former cell types has led to the proposal that a haemoprotein is involved in the detection of the PO₂ levels. Here, we report the effect of CO on the hypoxic pulmonary vasoconstriction (HPV). Pulmonary arterial pressure (PAP) was measured in an in situ, blood-perfused lung preparation. PAP in normoxia (20% O₂, 5% CO₂) was 15.2±1.8 mmHg, and hypoxia (2% O₂, 5% CO₂) produced a ΔPAP of 6.3±0.4 mmHg. Addition of 8% or 15% CO to the hypoxic gas mixture reduced the ΔPAP by 88.3±2.7% and 78.2±6.1% respectively. The same levels of CO did not affect normoxic PAP nor reduced the ΔPAP produced by angiotensin II. The effect of CO was studied after inhibition of the NO-cyclic guanosine monophosphate (cGMP) cascade with N-methyl-l-arginine (5·10^–5 M) or methylene blue (1.4·10^–4 M). It was found that both inhibitors more than doubled the hypoxic ΔPAP without altering the effectiveness of CO to inhibit the HPV. In in vitro experiments we verified the inhibition of guanylate cyclase by measuring the levels of cGMP in segments of the pulmonary artery. Cyclic GMP levels were 1.4±0.2 (normoxia), 2.5±0.3 (hypoxia) and 3.3±0.5 pmole/mg tissue (hypoxia plus 8% CO); sodium nitroprusside increased normoxic cGMP levels about fourfold. Methylene blue reduced cGMP levels to less than 10% in all cases, and abolished the differences among normoxic, hypoxic and hypoxic plus CO groups. It is concluded that CO inhibits HPV by a NO-cGMP independent mechanism and it is proposed that a haemoprotein could be involved in O₂-sensing in PSMC. Received: 17 March 1997 / Received after revision: 10 June 1997 / Accepted: 11 July 1997     

Cystathionine-gamma-lyase inhibitor attenuates acute lung injury induced by acute pancreatitis in rats

Introduction

Acute pancreatitis (AP) is known to induce injuries to extrapancreatic organs. Because respiratory dysfunction is the main cause of death in patients with severe AP, acute pancreatitis-associated lung injury (APALI) is a great challenge for clinicians. This study aimed to investigate the potential role of hydrogen sulfide (H₂S) in the pathogenesis of APALI.

Material and methods

Fifty-four SD rats were randomly divided into three groups: the AP group of rats that received injection of sodium deoxycholate into the common bile duct, the control group that underwent a sham operation, and the treatment group made by intraperitoneal injection of propargylglycine (PAG), an inhibitor of cystathionine-γ-lyase (CSE), into rats with AP. Histopathology of the lung was examined and the expression of CSE and TNF-α mRNA in lung tissue was detected by real-time polymerase chain reaction. The H₂S level in the serum was detected spectrophotometrically.

Results

The serum concentration of H2S and CSE and TNF-α expression in the lung were increased in AP rats modeled after 3 h and 6 h than in control rats (p < 0.05). Intraperitoneal injection of PAG could reduce the serum concentration of H₂S, reduce CSE and TNF-α expression, and alleviate the lung pathology (p < 0.05).

Conclusions

Taken together, our findings suggest that the H₂S/CSE system is crucially involved in the pathological process of APALI and represents a novel target for the therapy of APALI.     

TIPE2 ameliorates lipopolysaccharide-induced apoptosis and inflammation in acute lung injury

Inflammation Research - Tumour necrosis factor-α-induced protein 8-like 2 (TIPE2) has strong anti-inflammatory properties. However, it is unknown whether increased TIPE2 is protective against...     

Role of CFTR expressed by neutrophils in modulating acute lung inflammation and injury in mice

Objective and design  

Cystic fibrosis transmembrane conductance regulator (CFTR) regulates infection and inflammation. In this study, we investigated whether a lack of functional CFTR in neutrophils would promote lipopolysaccharide (LPS)-induced lung inflammation and injury.     

L-精氨酸对大鼠脂多糖致急性肺损伤的影响及机理

目的:探讨L-精氨酸对大鼠急性肺损伤的影响及机理.方法:采用尾静脉注射脂多糖(lipopolysaccharide,LPS)制备大鼠急性肺损伤模型.将45只大鼠随机分为三组:生理盐水对照组(NS组)、急性肺损伤模型组(LPS组)和L-精氨酸预处理组(L-Arg组)(n=15),再各分为2、6、24 h三个时间点.LPS组尾静脉注射LPS(6 mg/kg)制备急性肺损伤模型,L-Arg组在造模前0.5 h腹腔注射L-Arg 500 mg/kg.测定各组大鼠不同时间点的动脉血气分析,肺组织湿/干重(W/D)比,肺组织HE病理切片,ELISA法测定血清TNF-α,硝酸还原酶法测定血清NO,Real Time-PCR法测定肺组织iNOSmRNA.结果:LPS组动脉血氧降低、W/D增高、血清TNF-α及NO增高、肺组织iNOSmRNA增高,且与对照组比较有显著差异(P<0.05),肺组织HE病理切片有肺损伤改变.L-Arg组肺损伤有改善,上述检测指标与LPS组有显著差异(P<0.05).结论:L-精氨酸预处理对LPS致大鼠急性肺损伤有保护作用.     

衰老大鼠急性肺损伤诱导肾功能受损

目的:观察衰老大鼠的急性肺损伤(ALI)是否可进一步诱导肾功能受损。方法:Wistar雄性大鼠40只, 复制成衰老模型, 然后再随机分成对照组(静脉注射生理盐水), ALI组(静脉注射脂多糖, LPS)及LPS组(左心室内注射LPS), 后两组再分2h及6h组。每组8只。注LPS后2h或6h收集血并取肺、肾。制备肺、肾组织匀浆待测。结果:ALI组在注LPS后仅至6h时血中肌酐(Cr)、尿素氮(BUN)含量才有显著升高(均P＜0.01)。而LPS组Cr、BUN含量均无显著升高。ALI组血中乳酸(LD)、丙二醛(MDA)及一氧化氮(NO)含量在注LPS后2h时均显著升高(P＜0.05, P＜0.01);而肺组织中谷胱甘肽过氧化物酶(GSH-P_X)及Na⁺-K⁺-ATPase活性均显著下降(均P＜0.01);上述变化持续至观察的6h时。ALI组在注LPS后仅至6h时, 肾组织中MDA、NO含量才有显著升高(均P＜0.01)及GSH-P_X、Na⁺-K⁺-ATPase活性显著下降(P＜0.01)。而在LPS组, 除注LPS后2h时的血中和2h、6h的肺组织中NO含量显著升高(均P＜0.05)及2h时的肺组织中Na⁺-K⁺-ATPase活性显著下降(P＜0.05)外, 其它均无显著变化。结论:给衰老大鼠静脉内注射5mg/kg的LPS可致ALI, 并可进一步诱导肾功能受损。