Body temperature control in sepsis-induced acute lung injury

Body temperature is precisely regulated to maintain homeostasis in homeothermic animals. Although it remains unproved whether change of body temperature constitutes a beneficial or a detrimental component of the septic response, temperature control should be an important entity in septic experiments. We investigated the effect of body temperature control on the lipopolysaccharide (LPS)-induced lung injury. Acute lung injury in rats was induced by intratracheal spray of LPS and body temperature was either clamped at 37 degrees C for 5 hours or not controlled. The severity of lung injury was evaluated at the end of the experiment. Intratracheal administration of aerosolized LPS caused a persistent decline in body temperature and a significant lung injury as indicated by an elevation of protein-concentration and LDH activity in the bronchoalveolar lavage (BAL) fluid and wet/dry weight (W/D) ratio of lungs. Administration of LPS also caused neutrophil sequestration and lipid peroxidation in the lung tissue as indicated by increase in myeloperoxidase (MPO) activity and malondialdehyde (MDA) production, respectively. Control of body temperature at 37 degrees C after LPS (LPS/BT37, n = 11) significantly reduced acute lung injury as evidenced by decreases in BAL fluid protein concentration (983 +/- 189 vs. 1403 +/- 155 mg/L) and LDH activity (56 +/- 10 vs. 123 +/- 17 deltamAbs/min) compared with the LPS group (n = 11). Although the W/D ratio of lung and MDA level were lower in the rats received temperature control compared with those received LPS only, the differences were not statistically significant. Our results demonstrated that intratracheal administration of aerosolized LPS induced a hypothermic response and acute lung injury in rats and controlling body temperature at a normal range may alleviate the LPS-induced lung injury.     

Granisetron protects polymicrobial sepsis-induced acute lung injury in mice

Sepsis is a serious condition with a high mortality rate worldwide. Granisetron is an anti-nausea drug for patients undergoing chemotherapy. Here we aimed to identify the novel effect of granisetron on sepsis-induced acute lung injury (ALI). Our results showed that mice treated with granisetron displayed less severe lung damage than controls. Granisetron administration reduced pulmonary neutrophil recruitment after CLP. Moreover, the expressions of Cxcl1 and Cxcl2 were diminished in the presence of granisetron in THP-1 macrophages after lipopolysaccharide exposure. Additionally, granisetron could inhibit the activation of p38 MAPK and NLRP3 inflammasome both in vivo and in vitro. Collectively, granisetron protects against sepsis-induced ALI by suppressing macrophage Cxcl1/Cxcl2 expression and neutrophil recruitment in the lung.     

Positive end-expiratory pressure and surfactant decrease lung injury during initiation of ventilation in fetal sheep

The initiation of ventilation in preterm, surfactant-deficient sheep without positive end-expiratory pressure (PEEP) causes airway injury and lung inflammation. We hypothesized that PEEP and surfactant treatment would decrease the lung injury from initiation of ventilation with high tidal volumes. Fetal sheep at 128-day gestational age were randomized to ventilation with: 1) no PEEP, no surfactant; 2) 8-cmH(2)O PEEP, no surfactant; 3) no PEEP + surfactant; 4) 8-cmH(2)O PEEP + surfactant; or 5) control (2-cmH(2)O continuous positive airway pressure) (n = 6-7/group). After maternal anesthesia and hysterotomy, the head and chest were exteriorized, and the fetus was intubated. While maintaining placental circulation, the fetus was ventilated for 15 min with a tidal volume escalating to 15 ml/kg using heated, humidified, 100% nitrogen. The fetus then was returned to the uterus, and tissue was collected after 30 min for evaluation of early markers of lung injury. Lambs receiving both surfactant and PEEP had increased dynamic compliance, increased static lung volumes, and decreased total protein and heat shock proteins 70 and 60 in bronchoalveolar lavage fluid compared with other groups. Ventilation, independent of PEEP or surfactant, increased mRNA expression of acute phase response genes and proinflammatory cytokine mRNA in the lung tissue compared with controls. PEEP decreased mRNA for cytokines (2-fold) compared with groups receiving no PEEP. Surfactant administration further decreased some cytokine mRNAs and changed the distribution of early growth response protein-1 expression. The use of PEEP during initiation of ventilation at birth decreased early mediators of lung injury. Surfactant administration changed the distribution of injury and had a moderate additive protective effect.     

Effects of surfactant distribution and ventilation strategies on efficacy of exogenous surfactant

The effectsof both surfactant distribution patterns and ventilation strategiesutilized after surfactant administration were assessed in lung-injuredadult rabbits. Animals received 50 mg/kg surfactant via intratrachealinstillation in volumes of either 4 or 2 ml/kg. A subset ofanimals from each treatment group was euthanized for evaluation of theexogenous surfactant distribution. The remaining animals wererandomized into one of three ventilatory groups: group1 [tidal volume(VT) of 10 ml/kg with 5 cmH₂O positive end-expiratorypressure (PEEP)]; group 2 (VT of 5 ml/kg with 5 cmH₂O PEEP); orgroup 3 (VT of 5 ml/kg with 9 cmH₂O PEEP). Animals wereventilated and monitored for 3 h. Distribution of the surfactant wasmore uniform when it was delivered in the 4 ml/kg volume. When thedistribution of surfactant was less uniform, arterial PO₂ values were greater ingroups 2 and3 compared with group1. Oxygenation differences among the differentventilation strategies were less marked in animals with the moreuniform distribution pattern of surfactant (4 ml/kg). In bothsurfactant treatment groups, a high mortality was observed with theventilation strategy used for group 3.We conclude that the distribution of exogenous surfactant affects theresponse to different ventilatory strategies in this model of acutelung injury.

     

Ibuprofen attenuates plasma tumor necrosis factor activity during sepsis-induced acute lung injury.

Plasma tumor necrosis factor (TNF) activity, cardiac index, extravascular lung water, systemic and pulmonary arterial pressures, pulmonary vascular resistance index, and arterial PO2 were monitored for 300 min in four groups of anesthetized pigs: saline-infused animals (n = 5), saline-infused animals given ibuprofen (12.5 mg/kg iv) at 0 and 120 min (n = 4), animals infused for 60 min with live Pseudomonas aeruginosa (Ps, 5 x 10(8) organisms/ml at 0.3 ml.20 kg-1.min-1, n = 6), and animals infused for 60 min with Ps plus ibuprofen administered at 0 and 120 min (n = 4). Infusion of Ps induced significant elevations (greater than 4-fold increase in units/ml of TNF by 60 min, P less than 0.05) in plasma TNF activity (L929 cytolysis assay) and alterations (P less than 0.05) in all hemodynamic and pulmonary parameters within 30-60 min. Ibuprofen administration in sepsis significantly decreased peak TNF activity by 2 units/ml and attenuated many of the physiological alterations due to sepsis. These results show that ibuprofen attenuates sepsis-induced injury and that alterations of acute septic insult are correlated with reduced plasma TNF activity in septic animals given ibuprofen.     

The effect of diet-induced serum hypercholesterolemia on the surfactant system and the development of lung injury

Acute respiratory distress syndrome (ARDS) is a pulmonary disorder associated with alterations to the pulmonary surfactant system. Recent studies showed that supra-physiological levels of cholesterol in surfactant contribute to impaired function. Since cholesterol is incorporated into surfactant within the alveolar type II cells which derives its cholesterol from serum, it was hypothesized that serum hypercholesterolemia would predispose the host to the development of lung injury due to alterations of cholesterol content in the surfactant system.Wistar rats were randomized to a standard lab diet or a high cholesterol diet for 17–20 days. Animals were then exposed to one of three models of lung injury: i) acid aspiration ii) ventilation induced lung injury, and iii) surfactant depletion. Following physiological monitoring, lungs were lavaged to obtain and analyze the surfactant system.The physiological results showed there was no effect of the high cholesterol diet on the severity of lung injury in any of the three models of injury. There was also no effect of the diet on surfactant cholesterol composition. Rats fed a high cholesterol diet had a significant impairment in surface tension reducing capabilities of isolated surfactant compared to those fed a standard diet exposed to the surfactant depletion injury. In addition, only rats that were exposed to ventilation induced lung injury had elevated levels of surfactant associated cholesterol compared to non-injured rats.It is concluded that serum hypercholesterolemia does not predispose rats to altered surfactant cholesterol composition or to lung injury. Elevated cholesterol within surfactant may be a marker for ventilation induced lung damage.     

Map kinase phosphatase 5 protects against sepsis-induced acute lung injury

Mitogen-activated protein kinases (MAPKs) play a critical role in inflammation. Although activation of MAPK in inflammatory cells has been studied extensively, much less is known about the inactivation of these kinases. MAPK phosphatase 5 (MKP5) is a member of the dual-specificity phosphatase family that dephosphorylates activated MAPKs. Here we report that MKP5 protects sepsis-induced acute lung injury. Mice lacking MKP5 displayed severe lung tissue damage following LPS challenge, characterized with increased neutrophil infiltration and edema compared with wild-type (WT) controls. In response to LPS, MKP5-deficient macrophages produced significantly more inflammatory factors including inflammatory cytokines, nitric oxide, and superoxide. Phosphorylation of p38 MAPK, JNK, and ERK were enhanced in MKP5-deficient macrophages upon LPS stimulation. Adoptive transfer of MKP5-deficient macrophages led to more severe lung inflammation than transfer of WT macrophages, suggesting that MKP5-deficient macrophages directly contribute to acute lung injury. Taken together, these results suggest that MKP5 is crucial to homeostatic regulation of MAPK activation in inflammatory responses.     

硫化氢对大鼠内毒素性急性肺损伤肺泡表面活性物质的影响

目的：观察脂多糖（LPS）所致内毒素性急性肺损伤（ALI）大鼠肺泡表面活性物质（PS）的变化及硫化氢（H2S）对PS的影响,探讨H2S对肺脏的作用机制。方法：雄性SD大鼠共48只,随机分为6组（n=8）：空白对照组、LPS组、LPS＋NaHS低、中、高剂量组、LPS＋PPG组。空白对照组给予生理盐水,LPS组给予LPS,LPS＋NaHS低、中、高剂量组和LPS＋PPG组分别在给予LPS3h时腹腔注射低、中、高剂量氢硫化钠（NariS）或炔丙基甘氨酸（PPG）。各组均于给予生理盐水或LPS6h时电镜下观察肺泡Ⅱ型上皮细胞（AEC-Ⅱ）的形态改变,检测血浆中H2S含量、肺组织中胱硫醚-γ-裂解酶（CSE）活性、肺泡灌洗液（BALF）中总蛋白（1P）和总磷脂（TPL）含量、及肺组织中肺泡表面活性蛋白A、B、C（SP-A、B、C）mRNA表达的变化。结果：①与空白对照组比较,LPS组AEC-Ⅱ超微结构明显受损,血浆中H2S含量、肺组织中CSE活性、BALF中TPL的含量、及肺组织中SP-A、B、CmRNA表达均明显降低（P〈0．05,P〈0．01）,BALF中TP的含量明显增加（P〈0．01）;②与LPS组比较,LPS＋NaHS低、中、高剂量组,AEC-Ⅱ超微结构均有所恢复,血浆中H2S含量、肺组织中CSE海性、SP-AmRNA表达均明显升高（P〈0．05,P〈0．01）;LPS＋NaHS中、高剂量组BALF中吼含量明显增高,SP-BmRNA表达升高（P〈0．05）;LPS＋NaHS高剂量组BALF中,IP含量明显降低（P〈0．05）;LPS＋NaHS各剂量组SP-CznRNA表达无明显变化;③与LPS组比较,LPS＋PPG组AEC-Ⅱ超微结构仍损伤严重,血浆中H2S含量、肺组织中CSE活性、BALF中TPL的含量、及肺组织中SP-A、B、CmRNA表达均明显降低（P〈0．05）,BALF中TP的含量明显升高（P〈0．05）。结论：PS降低是内毒素性ALI的重要病理生理过程,H2S对LPS诱导的ALI有保护性作用,其机制可能与H2S对PS的调节有关。     

Nebulized vs. instilled exogenous surfactant in an adult lung injury model.

Three days after subcutaneous injection of N-nitroso-N-methylurethane (NNNMU) to induce lung injury, adult rabbits were mechanically ventilated and lung function was evaluated. Each animal then received either nebulized Survanta (Neb Surv), nebulized saline (Neb Saline), nebulized gas alone (Neb Gas), or tracheally instilled Survanta (Inst Surv). The ventilation efficiency index (VEI) value increased significantly compared with pretreatment values (P less than 0.01) over a 3-h treatment period for the Neb Surv animals, whereas VEI values for the other three groups decreased after treatment (P less than 0.05). Arterial PO2-to-fraction of inspired O2 ratios and dynamic compliance values significantly decreased after treatment for the Inst Surv group (P less than 0.05). Pressure-volume curves demonstrated a significantly greater volume at maximal pressure for the Neb Surv group compared with each of the other groups studied (P less than 0.01). The calculated quantity of surfactant recovered in lung tissue for the Neb Surv group was only 4.9 +/- 1.0 mg lipid/kg compared with 100 mg lipid/kg delivered to the Inst Surv group. Surfactant administered as an aerosol resulted in modest physiological improvements in this model of lung injury and was superior to the tracheal instillation technique.     

Protective effect of liposome-entrapped superoxide dismutase and catalase on bleomycin-induced lung injury in rats. II. Phospholipids of the lung surfactant.

The influence of liposome-entrapped catalase and/or superoxide dismutase on phospholipids of the lung surfactant in bleomycin-treated rats was investigated. Changes in phospholipid composition of lung surfactant were much pronounced in animals supplemented with antioxidant enzymes-loaded liposomes. It is suggested that liposomes are good carriers for drugs in bleomycin-induced lung injury treatment.     

Role of pulmonary microvascular endothelial cell apoptosis in murine sepsis-induced lung injury in vivo

Background

Sepsis remains a common and serious condition with significant morbidity and mortality due to multiple organ dysfunction, especially acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Sepsis-induced ALI is characterized by injury and dysfunction of the pulmonary microvasculature and pulmonary microvascular endothelial cells (PMVEC), resulting in enhanced pulmonary microvascular sequestration and pulmonary infiltration of polymorphonuclear leukocytes (PMN) as well as disruption of the normal alveolo-capillary permeability barrier with leak of albumin-rich edema fluid into pulmonary interstitium and alveoli. The role of PMVEC death and specifically apoptosis in septic pulmonary microvascular dysfunction in vivo has not been established.

Methods

In a murine cecal ligation/perforation (CLP) model of sepsis, we quantified and correlated time-dependent changes in pulmonary microvascular Evans blue (EB)-labeled albumin permeability with (1) PMVEC death (propidium iodide [PI]-staining) by both fluorescent intravital videomicroscopy (IVVM) and histology, and (2) PMVEC apoptosis using histologic fluorescent microscopic assessment of a panel of 3 markers: cell surface phosphatidylserine (detected by Annexin V binding), caspase activation (detected by FLIVO labeling), and DNA fragmentation (TUNEL labeling).

Results

Compared to sham mice, CLP-sepsis resulted in pulmonary microvascular barrier dysfunction, quantified by increased EB-albumin leak, and PMVEC death (PI+ staining) as early as 2 h and more marked by 4 h after CLP. Septic PMVEC also exhibited increased presence of all 3 markers of apoptosis (Annexin V+, FLIVO+, TUNEL+) as early as 30 mins – 1 h after CLP-sepsis, which all similarly increased markedly until 4 h. The time-dependent changes in septic pulmonary microvascular albumin-permeability barrier dysfunction were highly correlated with PMVEC death (PI+; r = 0.976, p < 0.01) and PMVEC apoptosis (FLIVO+; r = 0.991, p < 0.01). Treatment with the pan-caspase inhibitor Q-VD prior to CLP reduced PMVEC death/apoptosis and attenuated septic pulmonary microvascular dysfunction, including both albumin-permeability barrier dysfunction and pulmonary microvascular PMN sequestration (p < 0.05). Septic PMVEC apoptosis and pulmonary microvascular dysfunction were also abrogated following CLP-sepsis in mice deficient in iNOS (Nos2^−/−) or NADPH oxidase (p47^phox−/− or gp91^phox−/−) and in wild-type mice treated with the NADPH oxidase inhibitor, apocynin.

Conclusions

Septic murine pulmonary microvascular dysfunction in vivo is due to PMVEC death, which is mediated through caspase-dependent apoptosis and iNOS/NADPH-oxidase dependent signaling.     

Effect of exogenous surfactant instillation on experimental acute lung injury

Pulmonary surfactant replacement has previously been shown to be effective in the human neonatal respiratory distress syndrome. The value of surfactant replacement in models of acute lung injury other than quantitative surfactant deficiency states is, however, uncertain. In this study an acute lung injury model using rats with chronic indwelling arterial catheters, injured with N-nitroso-N-methylurethane (NNNMU), has been developed. The NNNMU injury was found to produce hypoxia, increased mortality, an alveolitis, and alterations in the pulmonary surfactant system. Alterations of surfactant obtained by bronchoalveolar lavage included a reduction in the phospholipid-to-protein ratio, reduced surface activity, and alterations in the relative percentages of the individual phospholipids compared with controls. Treatment of the NNNMU-injured rats with instilled exogenous surfactant (Survanta) improved oxygenation; reduced mortality to control values; and returned the surfactant phospholipid-to-protein ratio, surface activity, and, with the exception of phosphatidylglycerol, the relative percentages of individual surfactant phospholipids to control values.     

Anti-inflammatory effects of mangiferin on sepsis-induced lung injury in mice via up-regulation of heme oxygenase-1

Sepsis, a serious unbalanced hyperinflammatory condition, is a tremendous burden for healthcare systems, with a high mortality and limited treatment. Increasing evidences indicated that some active components derived from natural foods have potent anti-inflammatory properties. Here we show that mangiferin (MF), a natural glucosyl xanthone found in both mango and papaya, attenuates cecal ligation and puncture-induced mortality and acute lung injury (ALI), as indicated by reduced systemic and pulmonary inflammatory responses. Moreover, pretreatment with MF inhibits sepsis-activated mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B cells signaling, resulting in inhibiting production of proinflammatory mediators. Notably, MF dose-dependently up-regulates the expression and activity of heme oxygenase (HO)-1 in the lung of septic mice. Further, these beneficial effects of MF on the septic lung injury were eliminated by ZnPP IX, a specific HO-1 inhibitor. Our results suggest that MF attenuates sepsis by up-regulation of HO-1 that protects against sepsis-induced ALI through inhibiting inflammatory signaling and proinflammatory mediators. Thereby, MF may be effective in treating sepsis with ALI.