Acute lung injury in a rat model of intestinal ischemia-reperfusion: the potential time depended role of phospholipases A(2)

Cellular Signal Transduction Pathways Involved in Acute Lung Injury Induced by Intestinal Ischemia-Reperfusion

Intestinal ischemia-reperfusion (II/R) injury is a common type of tissue and organ injury, secondary to intestinal and mesenteric vascular diseases. II/R is characterized by a high incidence rate and mortality. In the II/R process, intestinal barrier function is impaired and bacterial translocation leads to excessive reactive oxygen species, inflammatory cytokine release, and even apoptosis. A large number of inflammatory mediators and oxidative factors are released into the circulation, leading to severe systemic inflammation and multiple organ failure of the lung, liver, and kidney. Acute lung injury (ALI) is the most common complication, which gradually develops into acute respiratory distress syndrome and is the main cause of its high mortality. This review summarizes the signal transduction pathways and key molecules in the pathophysiological process of ALI induced by II/R injury and provides a new therapeutic basis for further exploration of the molecular mechanisms of ALI induced by II/R injury. In particular, this article will focus on the biomarkers involved in II/R-induced ALI.

Pretreatment with Propofol Reduces Pulmonary Injury in a Pig Model of Intestinal Ischemia-Reperfusion via Suppressing the High-Mobility Group Box 1 Protein (HMGB1)/Toll-Like Receptor 4 (TLR4)/Protein Kinase R (PKR) Signaling Pathway

BACKGROUND Propofol improves rodent pulmonary injury after intestinal ischemia-reperfusion (IIR). However, its effect and underlying mechanisms in large animals remain unclear. Here, we examined whether pretreatment with propofol could relieve lung injury during IIR in pigs, then investigated the underlying mechanism. MATERIAL AND METHODS A porcine model of IIR-induced lung injury was built by clamping the super mesenteric artery for 2 h and loosening the clamp for 4 h. Randomized grouping was used, and pigs were assigned to a sham-operated group, an IIR with saline pretreatment group, and an IIR with propofol pretreatment group. Pulmonary histopathologic changes, permeability, and oxygenation were assessed to evaluate the effect of propofol. We assessed levels of methane dicarboxylic aldehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO), high-mobility group box 1 protein (HMGB1), Toll-like receptor 4 (TLR4), and double-stranded RNA activated protein kinase R (PKR) to investigate the underlying mechanism. RESULTS IIR caused severe lung damage, including morphological changes, high permeability, airway resistance, low static compliance, hypoxemia, and acidemia. Pulmonary and plasma MDA content and MPO activity increased, whereas SOD activity decreased. The HMGB1/TLR4/PKR signaling pathway was activated following IIR. Pretreatment with propofol markedly attenuated lung injury (such as reducing the lung edema and permeability), increased MDA content and MPO activity, and restored SOD activity induced by IIR, accompanied by inhibiting the effect of the HMGB1/TLR4/PKR signaling pathway. CONCLUSIONS IIR caused acute lung injury in pigs. Pretreatment with propofol alleviated the lung injury, which was related to its suppression of the HMGB1/TLR4/PKR signaling pathway.

Secretory Phospholipase A2-IIA Protein and mRNA Pools in Extracellular Vesicles of Bronchoalveolar Lavage Fluid from Patients with Early Acute Respiratory Distress Syndrome: A New Perception in the Dissemination of Inflammation?

Secretory phospholipase-IIA A₂ (sPLA₂-IIA) is expressed in a variety of cell types under inflammatory conditions. Its presence in the bronchoalveolar lavage (BAL) fluid of patients with acute respiratory distress syndrome (ARDS) is associated with the severity of the injury. Exosomal type extracellular vesicles, (EVs), are recognized to perform intercellular communication. They may alter the immune status of recipient target cells through cargo shuttling. In this work, we characterized the exosomal type EVs isolated from BAL fluid of patients with early and late ARDS as compared to control/non-ARDS patients, through morphological (confocal and electron microscopy) and biochemical (dynamic light scattering, qRT-PCR, immunoblotting) approaches. We provide evidence for the presence of an sPLA₂-IIA-carrying EV pool that coprecipitates with exosomes in the BAL fluid of patients with ARDS. PLA2G2A mRNA was present in all the samples, although more prominently expressed in early ARDS. However, the protein was found only in EVs from early phase ARDS. Under both forms, sPLA₂-IIA might be involved in inflammatory responses of recipient lung cells during ARDS. The perception of the association of sPLA₂-IIA to the early diagnosis of ARDS or even with a mechanism of development and propagation of lung inflammation can help in the adoption of appropriate and innovative therapeutic strategies.

Antiplatelet Therapy for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a common and devastating syndrome that contributes to serious morbidities and mortality in critically ill patients. No known pharmacologic therapy is beneficial in the treatment of ARDS, and the only effective management is through a protective lung strategy. Platelets play a crucial role in the pathogenesis of ARDS, and antiplatelet therapy may be a potential medication for ARDS. In this review, we introduce the overall pathogenesis of ARDS, and then focus on platelet-related mechanisms underlying the development of ARDS, including platelet adhesion to the injured vessel wall, platelet-leukocyte-endothelium interactions, platelet-related lipid mediators, and neutrophil extracellular traps. We further summarize antiplatelet therapy, including aspirin, glycoprotein IIb/IIIa receptor antagonists, and P2Y12 inhibitors for ARDS in experimental and clinical studies and a meta-analysis. Novel aspirin-derived agents, aspirin-triggered lipoxin, and aspirin-triggered resolvin D1 are also described here. In this narrative review, we summarize the current knowledge of the role of platelets in the pathogenesis of ARDS, and the potential benefits of antiplatelet therapy for the prevention and treatment of ARDS.

Mitochondrial separation protein inhibitor inhibits cell apoptosis in rat lungs during intermittent hypoxia

Obstructive sleep apnoea (OSA) is a very common sleep and breathing disorder that occurs in worldwide. It is important to develop a more effective treatment for OSA to overcome lung cell apoptosis during intermittent hypoxia (IH). A mitochondrial separation protein inhibitor (Mdivi-1) has been demonstrated to be a powerful tool for inhibiting apoptosis. In the present study, the protective effect and possible mechanism of apoptosis in lung cells during IH was investigated using in vivo and in vitro experiments. Following IH exposure for 4 weeks, the lung tissues of Sprague Dawley rats exhibited interstitial lesions, while Mdivi-1 reduced these pulmonary interstitial lesions. B-cell lymphoma (Bcl)-2 mRNA and protein expression levels were decreased however caspase-3, caspase-9 and dynamin-related protein 1 (Drp-1) mRNA and protein expression levels were increased. Following Mdivi-1 intervention, Bcl-2 mRNA and protein expression levels were increased while caspase-3, caspase-9 and Drp-1 mRNA and protein expression levels were decreased (P<0.05). After exposure to IH for 12 h, the apoptosis rate of WTRL1 cells in rats increased gradually with the IH time (P<0.05). Bcl-2 mRNA and protein expression levels were decreased, whereas caspase-3, caspase-9, cytochrome C (Cyt-C) and Drp-1 mRNA levels were increased, and caspase-3, caspase-9 and Drp-1 protein expression levels were increased. After Mdivi-1 intervention, Bcl-2 mRNA and protein expression levels were increased but caspase-3, caspase-9, Cyt-C and Drp-1 mRNA levels were decreased along with caspase-9, Cyt-C and Drp-1 protein expression levels which were decreased (P<0.05). The results of the present study suggest that Mdivi-1 may be a potential agent for treating OSA because it inhibits the mitochondrial pathway and reduces apoptosis.

Influences of Vagotomy on Gut Ischemia-Reperfusion Injury in Mice

BACKGROUND

How vagotomy affects host responses to gut ischemia-reperfusion (I/R) is unclear.

MATERIALS AND METHODS

Experiment 1: male Institute of Cancer Research mice (n = 22) were assigned to the I/R or the vago-I/R group. The I/R mice underwent 45-min superior mesenteric artery (SMA) occlusion. The vago-I/R mice received vagotomy before SMA occlusion. Survival was observed for 48 h.Experiment 2: mice (n = 55) were divided into four groups (Sham, vago, I/R, vago-I/R). Sham and vago groups did not undergo gut I/R. Mice were killed at 3 or 6 h after reperfusion, and cytokine levels in the plasma, jejunum, and ileum were evaluated. In addition, gut histology at 6 h was examined.Experiment 3: mice (n = 24) were divided into four groups as in Experiment 2. The small intestine was harvested at 3 h after reperfusion and the tissue was cultured ex vivo for 3 h. Cytokine levels of the culture supernatant were then measured.

RESULTS

Experiment 1: survival was significantly worse with vago-I/R than I/R.Experiment 2: along with severe gut injury, vago-I/R increased IL-6 and monocyte chemoattractant protein-1 (MCP-1) in plasma, IFN-γ in the jejunum and MCP-1 in the ileum, as compared with I/R. Significant positive correlations were noted between plasma and intestinal levels of pro-inflammatory cytokines (IL-6, MCP-1, and TNF-α).Experiment 3: MCP-1 in the jejunal culture medium was higher in the vago-I/R than in the I/R group.

CONCLUSIONS

Vagotomy worsens survival after gut I/R, together with increases in pro-inflammatory cytokines in both plasma and the gut in association with severe intestinal tissue damage.

Mangiferin protects against ‭intestinal ischemia/reperfusion-induced ‭liver injury: ‬‬Involvement of PPAR-‭γ, GSK-3β and Wnt/β-catenin pathway‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

AIM

Mangiferin (MF), a xanthonoid from Mangifera indica, possesses anti-inflammatory, immunomodulatory, and potent antioxidant effects; however, its protective effect against mesenteric ischemia/reperfusion (I/R)-induced liver injury has not been fully clarified. The study was designed to assess the possible mechanism of action of MF against mesenteric I/R model.

MAIN METHODS

Male Wister rats were treated with MF (20mg/kg, i.p) or the vehicle for 3 days before I/R, which was induced by clamping the superior mesenteric artery for 30min followed by declamping for 60min.

KEY FINDINGS

The mechanistic studies revealed that MF protected the 2 organs studied, viz., liver and intestine partly via increasing the content of β-catenin and PPAR-γ along with decreasing that of GSK-3β and the phosphorylated NF-қB-p65. MF antioxidant effect was evidenced by increasing contents of total antioxidant capacity and GST, besides normalizing that of MDA. Regarding the anti-inflammatory effect, MF reduced IL-1β and IL-6, effects that were mirrored on the tissue content of MPO. Moreover, MF possessed anti-apoptotic character evidenced by elevating Bcl-2 content and reducing that of caspase-3. In the serum, intestinal I/R increased the activity of ALT, AST, and creatine kinase.

SIGNIFICANCE

The intimated protective mechanisms of MF against mesenteric I/R are mediated, partially, by modulation of oxidative stress, inflammation, and apoptosis possibly via the involvement of Wnt/β-catenin/NF-қβ/ PPAR-γ signaling pathways.

Liporotein-associated phospholipase-A2 can be a diagnostic marker inthe early stage diagnosis of acute mesenteric ischemia

BACKGROUND/AIM

The purpose of this experimental study was to investigate the role of lipoprotein-associated phospholipase-A2 (Lp-PLA2) in the diagnosis of acute mesenteric ischemia (AMI) in the early stage.

MATERIALS AND METHODS

Twenty-seven New Zealand rabbits were randomly divided into 3 groups in this study. Blood specimens were obtained from the groups at hours 0, 1, 3, and 6. Using the blood samples drawn from all groups, Lp-PLA2 and C-reactive protein (CRP) parameters were investigated.

RESULTS

There was a significant rise in the levels of both Lp-PLA2 and CRP starting at hour 1 (P < 0.05) (hour 1; Lp-PLA2, P = 0.003) in the ischemia group. In the sham group, the levels of Lp-PLA2 and CRP started to rise at hour 3 (P < 0.05) (hour 3; Lp-PLA2, P = 0.011). At hour 6 of ischemia, the area under the ROC curve was 100%, and the cut-off value of 63.91 ng/mL revealed a sensitivity of 88% and a specificity of 100% for Lp-PLA2.

CONCLUSION

These findings showed the role of serum Lp-PLA2 and CRP levels in the early diagnosis of AMI. Thus, further studies are needed to describe the role of Lp-PLA2 in the early diagnosis of AMI.

Hydrogen water alleviates lung injury induced by one-lung ventilation

BACKGROUND

With the development of thoracic surgeries, one-lung ventilation (OLV) has been routinely used to facilitate surgical exposure. However, OLV can cause lung injury during the surgical process and becomes an important factor affecting the outcomes. To date, effective treatments for the prevention of lung injury caused by OLV are lacking. Hydrogen has been demonstrated to have effective protection against tissue injuries caused by oxidative stress, inflammation, and apoptosis. This study investigated the efficacy of hydrogen water consumption on the prevention of lung injury induced by OLV in rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n = 32, 240-260 g) were divided randomly into the following four groups: sham group, sham + H2 group, OLV group, OLV + H2 group. The rats drank hydrogen water or degassed hydrogen water for 4 wk before the operation and received OLV for 60 min and two-lung ventilation for 60 min. Lung tissues were assayed for wet-to-dry ratio, oxidative stress variables, proinflammatory cytokines, and hematoxylin-eosin staining.

RESULTS

Hydrogen water consumption reduced wet-to-dry weight ratio, malondialdehyde and myeloperoxidase activity and decreased the concentration of TNF-α, IL-1β, and IL-6 in the lung tissues compared with sham group and sham + H2 group. Hydrogen water consumption further attenuated NF-κB activation and caused histopathologic alterations.

CONCLUSIONS

Our data demonstrated that hydrogen water consumption ameliorated OLV-induced lung injury, and it may exert its protective role by its anti-inflammation, antioxidation and reducing NF-κB activity in the lung tissues.

Protective effects of icariin-mediated SIRT1/FOXO3 signaling pathway on intestinal ischemia/reperfusion-induced acute lung injury

Acute lung injury (ALI) is a common complication following intestinal ischemia/reperfusion (I/R) and is a major contributing factor to its high mortality rate. Sirtuin 1 (SIRT1), a NAD+-dependent deacetylase, has been reported to have an important role in apoptosis inhibition, oxidative stress resistance and cell lifespan extension through its deacetylation of forkhead box protein O3 (FOXO3). It has been demonstrated that icariin (ICA), a flavonoid extracted from Epimedium, upregulates SIRT1 expression. The aim of the present study was to examine whether ICA-mediated SIRT1/FOXO3 signaling pathway activation had a protective effect on intestinal I/R-induced ALI. The effects of ICA on intestinal I/R-induced ALI and its regulation of the SIRT1/FOXO3 signaling pathway on intestinal I/R-induced ALI were investigated in rats. The results demonstrated that ICA pretreatment markedly reduced intestinal I/R-induced ALI as indicated by histological alterations, including decreased tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), reduced oxidative stress, acetylated FOXO3 and B-cell lymphoma 2 (Bcl-2)-interacting mediator of cell death levels, and increased glutathione (GSH), GSH peroxidase, SIRT1, manganese superoxide dismutase and Bcl-2 levels in rat lung tissues. Furthermore, ICA pretreatment upregulated SIRT1 expression, which then downregulated FOXO3 acetylation. In conclusion, ICA exhibited significant protective effects in intestinal I/R-induced ALI. The protective effect of ICA may be attributed to the upregulation of SIRT1, which contributed to FOXO3 deacetylation and the modulation of downstream antioxidative and anti-apoptotic factors.

Gene set signature of reversal reaction type I in leprosy patients

Leprosy reversal reactions type 1 (T1R) are acute immune episodes that affect a subset of leprosy patients and remain a major cause of nerve damage. Little is known about the relative importance of innate versus environmental factors in the pathogenesis of T1R. In a retrospective design, we evaluated innate differences in response to Mycobacterium leprae between healthy individuals and former leprosy patients affected or free of T1R by analyzing the transcriptome response of whole blood to M. leprae sonicate. Validation of results was conducted in a subsequent prospective study. We observed the differential expression of 581 genes upon exposure of whole blood to M. leprae sonicate in the retrospective study. We defined a 44 T1R gene set signature of differentially regulated genes. The majority of the T1R set genes were represented by three functional groups: i) pro-inflammatory regulators; ii) arachidonic acid metabolism mediators; and iii) regulators of anti-inflammation. The validity of the T1R gene set signature was replicated in the prospective arm of the study. The T1R genetic signature encompasses genes encoding pro- and anti-inflammatory mediators of innate immunity. This suggests an innate defect in the regulation of the inflammatory response to M. leprae antigens. The identified T1R gene set represents a critical first step towards a genetic profile of leprosy patients who are at increased risk of T1R and concomitant nerve damage.

Leprosy type 1 reversal reactions (T1R) are an important cause of nerve damage in leprosy patients and accurate prediction of patients at increased risk of T1R is a major challenge of current leprosy control. The incidence of T1R differs widely from 6% to 67% of leprosy patients in different leprosy endemic settings. Whether or not this reflects the impact of unknown environmental triggers or differences in the genetic background across ethnicities is not known. We performed a comparative transcriptome analysis between leprosy patients affected and free of T1R in response to M. leprae antigens. As the discovery sample we enrolled cured leprosy patients who had been diagnosed with T1R at the time of leprosy diagnosis and leprosy patients who had never undergone T1R (retrospective arm). Whole genome transcriptome analysis after stimulation of blood with M. leprae antigen resulted in the definition of a T1R signature gene set. We validated the T1R gene set in RNA samples obtained from T1R-free patients at the time of leprosy diagnosis and followed for 3 years for development of T1R (prospective arm). These results confirm the role of innate factors in T1R and are a first step towards a predictive genetic T1R signature.

Protective effect of ginsenoside Rb1 against lung injury induced by intestinal ischemia-reperfusion in rats

Intestinal ischemia-reperfusion (I/R) is a critical event in the pathogenesis of multiple organ dysfunction syndromes (MODS). The lungs are some of the most vulnerable organs that are impacted by intestinal I/R. The aim of this study is to investigate whether ginsenoside Rb1 can ameliorate remote lung injury induced by intestinal I/R. Adult male Wistar rats were randomly divided into four groups: (1) a control, sham-operated group (sham group); (2) an intestinal I/R group subjected to 1 h intestinal ischemia and 2 h reperfusion (I/R group); (3) a group treated with 20 mg/kg ginsenoside Rb1 before reperfusion (Rb1-20 group); and (4) a group treated with 40 mg/kg ginsenoside Rb1 before reperfusion (Rb1-40 group). Intestinal and lung histology was observed. The malondialdehyde (MDA) levels in intestinal tissues were measured. Myeloperoxidase (MPO), TNF-α, MDA levels, wet/dry weight ratio and immunohistochemical expression of intracellular adhesion molecule-1 (ICAM-1) in lung tissues were assayed. In addition, a western blot of lung NF-kB was performed. Results indicated that intestinal I/R induced intestinal and lung injury, which was characterized by increase of MDA levels and pathological scores in intestinal tissues and MPO, TNF-α , MDA levels, wet/dry weight ratio and ICAM-1, NF-kB expression in the lung tissues. Ginsenoside Rb1 (20, 40 mg/kg) ameliorated intestinal and lung injury, decreased MPO, TNF-α, MDA levels, wet/dry weight ratio, ICAM-1 and NF-kB expression in lung tissues. In conclusion, ginsenoside Rb1 ameliorated the lung injuries by decreasing the NF-kB activation-induced inflammatory response.

Distinct gene loci control the host response to influenza H1N1 virus infection in a time-dependent manner

Background

There is strong but mostly circumstantial evidence that genetic factors modulate the severity of influenza infection in humans. Using genetically diverse but fully inbred strains of mice it has been shown that host sequence variants have a strong influence on the severity of influenza A disease progression. In particular, C57BL/6J, the most widely used mouse strain in biomedical research, is comparatively resistant. In contrast, DBA/2J is highly susceptible.

Results

To map regions of the genome responsible for differences in influenza susceptibility, we infected a family of 53 BXD-type lines derived from a cross between C57BL/6J and DBA/2J strains with influenza A virus (PR8, H1N1). We monitored body weight, survival, and mean time to death for 13 days after infection. Qivr5 (quantitative trait for influenza virus resistance on chromosome 5) was the largest and most significant QTL for weight loss. The effect of Qivr5 was detectable on day 2 post infection, but was most pronounced on days 5 and 6. Survival rate mapped to Qivr5, but additionally revealed a second significant locus on chromosome 19 (Qivr19). Analysis of mean time to death affirmed both Qivr5 and Qivr19. In addition, we observed several regions of the genome with suggestive linkage. There are potentially complex combinatorial interactions of the parental alleles among loci. Analysis of multiple gene expression data sets and sequence variants in these strains highlights about 30 strong candidate genes across all loci that may control influenza A susceptibility and resistance.

Conclusions

We have mapped influenza susceptibility loci to chromosomes 2, 5, 16, 17, and 19. Body weight and survival loci have a time-dependent profile that presumably reflects the temporal dynamic of the response to infection. We highlight candidate genes in the respective intervals and review their possible biological function during infection.

Ginsenoside Rb1 attenuates intestinal ischemia reperfusion induced renal injury by activating Nrf2/ARE pathway

Intestinal ischemia reperfusion (IIR) is a serious clinical condition associated with simultaneous multiple organ dysfunction. The aim of this study was to investigate the effects of ginsenoside Rb1 on IIR induced renal injury in mice. An intestinal ischemia reperfusion mouse model was established by superior mesenteric artery (SMA) occlusion for 45 min, followed by reperfusion for 2 h. IIR induced renal injury characterized by increase of BUN, Cr and NGAL in serum, MDA levels and decrease of SOD levels in the renal tissues. Ginsenoside Rb1 (30, 60 mg/kg) given intraperitoneally before reperfusion attennuated renal injury, which was associated with decrease of BUN, Cr and NGAL in serum, MDA levels and increase of SOD levels in the renal tissues. Furthermore, the immunohistochemistry and Western blot data showed that ginsenoside Rb1 dramatically reversed IIR induced renal injury, associated with upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in renal tissues. Our data suggests that ginsenoside Rb1 attenuates acute renal injury induced by intestinal ischemia reperfusion by activating the Nrf2/ARE pathway.

Liver cold preservation induce lung surfactant changes and acute lung injury in rat liver transplantation

AIM: To investigate the relationship between donor liver cold preservation, lung surfactant (LS) changes and acute lung injury (ALI) after liver transplantation.

METHODS: Liver transplantation models were established using male Wistar rats. Donor livers were preserved in University of Wisconsin solution at 4  °C for different lengths of time. The effect of ammonium pyrrolidinedithiocarbamate (PDTC) on ALI was also detected. All samples were harvested after 3 h reperfusion. The severity of ALI was evaluated by lung weight/body weight ratio, lung histopathological score, serum nitric oxide (NO) and endothelin (ET)-1 levels, lung tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels. Lung surfactants (LSs) were determined by micellar electrokinetic capillary chromatography.

RESULTS: With extended donor liver cold preservation time (CPT), lung histopathological scores, serum ET-1 levels, lung weight/body weight ratio and the level of TNF-α and IL-1β in lung were increased significantly in the 180-min group compared with the sham group (3.16 ± 0.28 vs 1.12 ± 0.21, P < 0.001; 343.59 ± 53.97 vs 141.53 ± 48.48, P < 0.001; 0.00687 ± 0.00037 vs 0.00557 ± 0.00056, P < 0.001; 17.5 ± 3.0 vs 1.3 ± 0.3, P < 0.001; 10.8 ± 2.3 vs 1.8 ± 0.4, P < 0.001), but serum NO levels decreased remarkably (74.67 ± 10.01 vs 24.97 ± 3.18, P < 0.001). The expression of lung phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) increased when CPT was < 120 min, and decreased when CPT was > 180 min (PC: 1318.89 ± 54.79 vs 1011.18 ± 59.99, P < 0.001; PE: 1504.45 ± 119.96 vs 1340.80 ± 76.39, P = 0.0019; PI: 201.23 ± 34.82 vs 185.88 ± 17.04, P = 0.2265; PS: 300.43 ± 32.95 vs 286.55 ± 55.55, P = 0.5054). All these ALI-associated indexes could be partially reversed by PDTC treatment.

CONCLUSION: Prolonged CPT could induce or inhibit the expression of LSs at the compensation or decompensation stage, and some antioxidants (e.g., PDTC) may reverse the pathological process partially.

TLR4 mediates lung injury and inflammation in intestinal ischemia-reperfusion

BACKGROUND

Splanchnic ischemia is common in critically ill patients, and it can result in injury not only of the intestine but also in distant organs, particularly in the lung. Local inflammatory changes play a pivotal role in the development of acute lung injury after intestinal ischemia, but the underlying molecular mechanisms are not fully understood. We sought to examine the role of Toll-like receptor 4 (TLR4) in the mouse model of intestinal ischemia-reperfusion (I/R)-induced lung injury and inflammation.

MATERIALS AND METHODS

Adult male TLR4 mutant (C3H/HeJ) mice and TLR4 wild-type (WT) (C3H/HeOuJ) mice were subjected to 40 min of intestinal ischemia by clamping the superior mesenteric artery followed by 6 h of reperfusion. Lung histology was assessed and parameters of pulmonary microvascular permeability, inflammatory cytokine expression, and neutrophil infiltration were measured. Activation of mitogen-activated protein kinases (MAPKs) and the transcription factors nuclear factor κB (NF-κB) and activator protein-1 (AP-1) in the lungs were also detected.

RESULTS

After intestinal I/R, lungs from TLR4 mutant mice demonstrated a significantly lower histological injury, a marked reduction of epithelial apoptosis associated with the decreased level of cleaved caspase-3 and the increased ratio of Bcl-xL to Bax proteins, and a large reduction in pulmonary vascular permeability and myeloperoxidase (MPO) activity in comparison with WT mice. TLR4 mutant mice also displayed marked decreases in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) expression. Following intestinal I/R, phosporylation of p38 MAPK and activation of NF-κB and AP-1 were significantly inhibited in lung tissue from TLR4 mutant mice compared with WT controls.

CONCLUSIONS

These data suggest that TLR4 plays an important role in the pathogenesis of intestinal I/R-induced acute lung injury and inflammation and that p38 kinase and NF-κB may be involved in TLR4 signaling-mediated lung inflammatory processes during intestinal I/R.

Intestinal lipid alterations occur prior to antibody-induced prostaglandin E2 production in a mouse model of ischemia/reperfusion

Ischemia/reperfusion (IR) induced injury results in significant tissue damage in wild-type, but not antibody-deficient, Rag-1(-/-) mice. However, Rag-1(-/-) mice sustain intestinal damage after administration of wild-type antibodies or naturally occurring, specific anti-phospholipid related monoclonal antibodies, suggesting involvement of a lipid antigen. We hypothesized that IR initiates metabolism of cellular lipids, resulting in production of an antigen recognized by anti-phospholipid antibodies. At multiple time points after Sham or IR treatment, lipids extracted from mouse jejunal sections were analyzed by electrospray ionization triple quadrupole mass spectrometry. Within 15min of reperfusion, IR induced significantly more lysophosphatidylcholine (lysoPC), lysophosphatidylglycerol (lysoPG) and free arachidonic acid (AA) production than Sham treatment. While lysoPC, lysoPG, and free AA levels were similar in C57Bl/6 (wild-type) and Rag-1(-/-) mice, IR led to Cox-2 activation and prostaglandin E(2) (PGE(2)) production in wild-type, but not in the antibody-deficient, Rag-1(-/-) mice. Administration of wild-type antibodies to Rag-1(-/-) mice restored PGE(2) production and intestinal damage. These data indicate that IR-induced intestinal damage requires antibodies for Cox-2 stimulated PGE(2) production but not for production of lysoPC and free AA.

Activated protein C and normal saline infusion might prevent deleterious effects of remote acute lung injury caused by intestinal ischemia-reperfusion: an experimental study in the rat model

BACKGROUND

Intestinal ischemia-reperfusion is a common medical event associated with both clinical and experimental distant organ injury. In particular, the lung tissue appears to be susceptible to injury resulting from systemic inflammatory mediator activation. Drotrecogin α (activated) or recombinant human activated protein C has antithrombotic, anti-inflammatory, and profibrinolytic properties. We hypothesized that APC infusion would decrease lung inflammation and ameliorate lung injury resulting from intestinal ischemia-reperfusion (IIR). A rat model of intestinal ischemia-reperfusion was used to test this hypothesis, and several parameters of lung injury were measured in lung samples.

MATERIAL AND METHODS

Forty Wistar albino rats were divided into four groups: a sham-operated group (Sham), an ischemic control group (IIR), an APC-infusion group (IIR'APC), and a normal saline-infusion group (IIR'NS) (n = 10, each). A marker for lipid peroxidation, malondialdehyde (MDA), free radical scavenger glutathione peroxidase (GSH-Px), an index of polymorphonuclear neutrophils, myeloperoxidase (MPO) activity, and lung polymorphonuclear leukocytes (PMNL) were investigated in the lung tissue samples.

RESULTS

MDA and MPO levels, and lung PMNL sequestration were decreased, but GSH-Px levels were increased in APC treated group versus IIR group. MDA levels were decreased and GSH-Px levels were increased in NS treated group versus IIR group. MPO levels and lung PMNL counts were similar across the IIR and IIR'NS groups.

CONCLUSIONS

This study documents that APC attenuates acute lung injury in intestinal ischemia-reperfusion. NS infusion had also some favorable effects regarding MDA and MPO.

Protective effect of NAC preconditioning against ischemia-reperfusion injury in piglet small bowel transplantation: effects on plasma TNF, IL-8, hyaluronic acid, and NO

BACKGROUND

Ischemia-reperfusion (I/R) injury is one of the main factors affecting the function and structure of small bowel transplantation (SBT), by generation of proinflammatory mediators such as reactive oxygen species, reactive nitrogen species, cytokines, and endotoxin. Experimental data have demonstrated that N-acetylcysteine (NAC) attenuates intestinal I/R injury. The objective of this study was to determine the effect of NAC preconditioning on the SBT-I/R induced inflammatory cascade, with particular focus on TNF, IL-8, hyaluronic acid, and NO.

METHODS

Fifteen domestic pigs were used as donors. Fifteen recipient animals were randomly assigned into two groups. Group 1: SBTx (n=7) served as controls and Group 2: SBTx (n=8) served as the experimental group (NAC administration).

RESULTS

NAC administration at a continuous 4 h intravenous bolus dose of 200 mg/kg of body weight, starting before initiation of bowel transplantation, resulted in statistically significant (P<0.05) higher plasma levels of NO, and lower plasma levels of hyaluronic acid, TNF-α, IL-8, and LDH compared with those of the control group, at the 360 min time point.

CONCLUSIONS

NAC confers a protective role in small bowel transplantation associated, partly, with NO generation and hyaluronic acid, TNF-α and IL-8 amelioration.

Protective effects of Salvia miltiorrhizae on multiple organs of rats with obstructive jaundice

PURPOSE

we aim to explore the protective effects of Salvia miltiorrhizae injection on multiple organs of obstructive jaundice (OJ) rats through observing the impact of this injection on the pathological alterations in these organs and the contents of endotoxin, PLA(2), and TNF-alpha in the blood.

METHODS

A total of 90 mice were randomly divided into sham-operated group, model-control group, and Salvia miltiorrhizae-treated group (n = 30). According to the duration of postoperative administration, each group was further divided into two subgroups, namely, 21 d subgroup (consecutive administration for 21 d, n = 15) and 28 d subgroup (consecutive administration for 28 d, n = 15). After administration, the pathological alterations in multiple organs were observed and the contents of endotoxin, PLA(2), and TNF-alpha in the blood were determined.

RESULTS

Compared to model control group, the number of dead rats in treated group decreased though there was no statistical difference between the two groups. The pathological alterations in the liver, kidney, and spleen in treated group showed varying degrees of mitigation. At all time points, the contents of plasma endotoxin declined significantly. On day 28, plasma PLA(2) content in treated group was significantly lower than that in model-control group.

CONCLUSION

Salvia miltiorrhizae injection is able to obviously reduce the contents of inflammatory mediators in the blood of OJ rats and exert some protective effects on multiple organs of these rats.

Panax notoginseng saponins attenuate acute lung injury induced by intestinal ischaemia/reperfusion in rats

BACKGROUND AND OBJECTIVE

Acute lung injury remains a challenge for both clinicians and scientists. The effects of Panax notoginseng saponins (PNS) on acute lung injury induced by intestinal ischaemia/reperfusion (II/R) were studied in rats.

METHODS

Forty-eight Wistar rats were randomly assigned to four groups: (1) a sham-operated group that received laparotomy without II/R (n= 12); (2) a sham + PNS group, which was identical to group 1 except for PNS treatment (n= 12); (3) an II/R group that had 1 h of intestinal ischaemia followed by 3 h of reperfusion (n= 12); and (4) an II/R + PNS group that received 100 mg/kg of PNS, i.v., 15 min before reperfusion (n= 12). The effects of PNS administration on lung tissue histology, activities of oxidant and antioxidant enzymes, levels of malondialdehyde, nitric oxide and inducible nitric oxide synthase activity were examined. Levels of surfactant protein B, cell numbers in BAL fluid and plasma levels of pro-inflammatory cytokines were also examined.

RESULTS

Compared with the II/R group, pulmonary parenchymal damage, activities of oxidant enzymes, levels of malondialdehyde and nitric oxide, inducible nitric oxide synthase activity in lung tissue, and plasma levels of pro-inflammatory cytokines were significantly reduced by PNS treatment. In addition, the decreases in antioxidant enzyme activities were prevented in the II/R + PNS group. Total leukocyte and neutrophil counts were significantly decreased by PNS treatment. The decline in surfactant protein B levels in BAL fluid was reduced in the II/R + PNS group compared with the II/R group.

CONCLUSIONS

Administration of PNS before reperfusion injury alleviates acute lung injury induced by II/R, and this is attributable to the antioxidant and anti-inflammatory effects of PNS.

Phospholipase A2 subclasses in acute respiratory distress syndrome

Phospholipases A2 (PLA2) catalyse the cleavage of fatty acids esterified at the sn-2 position of glycerophospholipids. In acute lung injury-acute respiratory distress syndrome (ALI-ARDS) several distinct isoenzymes appear in lung cells and fluid. Some are capable to trigger molecular events leading to enhanced inflammation and lung damage and others have a role in lung surfactant recycling preserving lung function: Secreted forms (groups sPLA2-IIA, -V, -X) can directly hydrolyze surfactant phospholipids. Cytosolic PLA2 (cPLA2-IVA) requiring Ca2+ has a preference for arachidonate, the precursor of eicosanoids which participate in the inflammatory response in the lung. Ca(2+)-independent intracellular PLA2s (iPLA2) take part in surfactant phospholipids turnover within alveolar cells. Acidic Ca(2+)-independent PLA2 (aiPLA2), of lysosomal origin, has additionally antioxidant properties, (peroxiredoxin VI activity), and participates in the formation of dipalmitoyl-phosphatidylcholine in lung surfactant. PAF-AH degrades PAF, a potent mediator of inflammation, and oxidatively fragmented phospholipids but also leads to toxic metabolites. Therefore, the regulation of PLA2 isoforms could be a valuable approach for ARDS treatment.