Toll-like receptor 4-dependent responses to lung injury in a murine model of pulmonary contusion

Multicompartmental Trauma Induces Persistent Inflammation and Organ Injury

INTRODUCTION

Previous preclinical models of multicompartmental injury have investigated its effects for durations of less than 72 h and the long-term effects have not been defined. We hypothesized that a model of multicompartmental injury would result in systemic inflammation and multiorgan dysfunction that persists at 1 wk.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 16/group) underwent polytrauma (PT) (unilateral right lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures) and were compared to naive controls. Weight, hemoglobin, plasma neutrophil gelatinase-associated lipocalin, and plasma toll-like receptor 4 were evaluated on days two and seven. Bilateral lungs were sectioned, stained and assessed for injury at day seven. Comparisons were performed in Graphpad with significance defined as ∗P <0.05.

RESULTS

Rats who underwent PT had significant weight loss and anemia at day 2 (P = 0.001) compared to naïve rats which persisted at day 7 (P = 0.001). PT rats had elevated plasma neutrophil gelatinase-associated lipocalin at day 2 compared to naïve (P <0.0001) which remained elevated at day 7 (P <0.0001). Plasma toll-like receptor 4 was elevated in PT compared to naïve at day 2 (P = 0.03) and day 7 (P = 0.01). Bilateral lungs showed significant injury in PT cohorts at day 7 compared to naïve (P <0.0004). PT males had worse renal function at day seven compared to females (P = 0.02).

CONCLUSIONS

Multicompartmental trauma induces systemic inflammation and multiorgan dysfunction without recovery by day seven. However, females demonstrate improved renal recovery compared to males. Long-term assessment of preclinical PT models are crucial to better understand and evaluate future therapeutic immunomodulatory and anti-inflammatory treatments.

Diesel vehicles-derived PM2.5 induces lung and cardiovascular injury attenuates by Securiniga suffruticosa: Involvement of NF-κB-mediated NLRP3 inflammasome activation pathway

Respiratory exposure to Particulate matter (PM), including Diesel exhaust particulate (DEP), causes oxidative stress-induced lung inflammation. Especially, fine particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) is a serious air pollutant associated with various health problems including cardiovascular diseases. The present study aimed to examine the inhibitory effect of Securiniga suffruticosa (S. suffruiticosa) on DEP and PM-induced lung and cardiovascular diseases. Mice inhaled DEP by using nebulizer chamber for two weeks. Treatment with S. suffruiticosa reduced the expression of C-X-C motif ligand 1/2 in bronchoalveolar lavage fluid and Muc5ac, ICAM-1, TNF-⍺, IL-6 mRNA in lung were also attenuated by S. suffruiticosa. In thoracic aorta, DEP increased CAMs, TNF-⍺ and inflammasome markers such as NLRP3, Caspase-1, and ASC. However, S. suffruiticosa suppressed these levels. S. suffruiticosa inhibited PM2.5 induced production of intracellular reactive oxygen species (ROS); and inhibited the translocation of NF-κB p65 to the nucleus in human umbilical vein endothelial cells. Taken together, this study proved that exposure to PM2.5 induced both lung and vascular inflammation, however, S. suffruiticosa attenuated this injury via the downregulation of the NLRP3 signaling pathway. These findings suggest that S. suffruiticosa may have potential therapeutic benefit against air pollution-mediated lung and cardiovascular diseases.

Sulforaphane suppresses lipopolysaccharide- and Pam3CysSerLys4-mediated inflammation in chronic obstructive pulmonary disease via toll-like receptors

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory disease of the airway that represents a large global disease burden. Inflammation is a prominent feature of COPD and represents an important target for treatment. Toll‐like receptors (TLRs) are pattern recognition receptors that detect invading microorganisms and nonmicrobial endogenous molecules to trigger inflammatory responses during host defense and tissue repair. The TLR signaling pathway is closely linked to the pathogenesis of COPD. Sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables, is well known for its anti‐inflammatory activities. However, the molecular function of SFN in inhibition of COPD inflammation has yet to be fully elucidated. In this study, we investigated the effects of SFN on lipopolysaccharide (LPS)‐ or Pam3CysSerLys4 (Pam3CSK4)‐induced inflammation in monocyte‐derived macrophages (MDMs) from patients with COPD. MDMs from patients with COPD showed higher expression levels of TLR2, TLR4 and downstream myeloid differentiation factor 88 (MyD88) than healthy controls, along with increased secretion of interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α) (P < 0.05). Stimulation with TLR ligands (Pam3CSK4 and LPS) up‐regulated the levels of TLR2, TLR4 and MyD88 in MDMs from patients with COPD and induced the release of IL‐6 and TNF‐α (P < 0.05). Pretreatment of MDMs from patients with COPD with SFN significantly suppressed Pam3CSK4‐ or LPS‐induced TLR2, TLR4 and MyD88 expression, along with a reduction in the production of IL‐6 and TNF‐α (P < 0.05). Collectively, these data indicate that SFN exerts its anti‐inflammatory activity in COPD by modulating the TLR pathway. SFN may represent a potential therapeutic agent for the treatment of COPD.

Selenium Deficiency via the TLR4/TRIF/NF-κB Signaling Pathway Leading to Inflammatory Injury in Chicken Spleen

The aim of the present study was to investigate the effect of selenium (Se) deficiency on the expression of the toll-like receptor (TLR) signal transduction pathway in the spleen of chickens and explore the relationship between the TLR4/TRIF/NF-κB signaling pathway and inflammatory spleen injury. A total of 200 one-day-old healthy broilers were allocated to two groups. The experimental group was fed a self-made low-Se diet (0.004 mg/kg) while the control group was fed a complete formula feed (0.2 mg/kg) for 15, 25, 35, 45, and 55 days, respectively. We observed histopathological changes in the chicken spleens. The messenger RNA(mRNA) expression levels of 8 kinds of ChTLRs, myeloid differential protein-88 (MyD88), toll-interleukine-1 receptor domain-containing adapter-inducing interferon-β (TRIF), nuclear factor-κB (NF-κB), and cytokine (IL-6, TNF-α, IL-2, and IFN-γ) were detected via quantitative real-time PCR. Western blotting was used to detect the protein expression level of TLR4. Then principal component analysis (PCA) was used to analyze the correlation between the ChTLRs, MyD88, TRIF, and NF-κB. The results showed that the boundary between red pulp and white pulp was unclear, the number of lymphocytes decreased, and the nucleus was fragmented and dissolved in the experimental group at 25-55 days. At 15-45 days, the relative expression of TLR4 mRNA was higher than in the control group, and the difference was extremely significant on day 15 (P < 0.01).The relative expression of TRIF mRNA in the experimental group was higher than in the control group at 25-55 days, and the relative expression of NF-κB mRNA in the experimental group was higher than in the control group at 15-45 days. The relative expression of IL-6 mRNA in the experimental group was higher than in the control group at 15-45 days. The protein expression level of TLR4 in the experimental group was higher than in the control group at 15-45 days. The PCA results showed that there was a strong correlation between TLR4, TRIF, and component 1. The results suggest that TLR4 plays an important role in regulating the expression of inflammatory cytokines in the spleens of Se-deficient chickens, and Se deficiency may cause inflammatory injury through the TLR4/TRIF/NF-κB signaling pathway in chicken spleen.

Early local neutralization of CC16 in sepsis‑induced ALI following blunt chest trauma leads to delayed mortality without benefitting overall survival

Blunt thoracic trauma (TxT) is a common injury pattern in polytraumatized patients. When combined with a secondary trigger, TxT often results in acute lung injury (ALI), which negatively affects outcomes. Recent findings suggest that ALI is caused by both local and systemic inflammatory reactions. Club cell protein (CC)16 is an anti‑inflammatory peptide associated with lung injury following TxT. Recently, the anti‑inflammatory properties of endogenous CC16 in a murine model of TxT with subsequent cecal‑ligation and puncture (CLP) as the secondary hit were demonstrated by our group. The present study aimed to determine whether CC16 neutralization improves survival following 'double‑hit'‑induced ALI. For this purpose, a total of 120 C57BL/6N mice were subjected to TxT, followed by CLP after 24 h. Sham‑operated animals underwent anesthesia without the induction of TxT + CLP. CC16 neutralization was performed by providing a CC16 antibody intratracheally following TxT (early) or following CLP (late). Survival was assessed in 48 animals for 6 days after CLP. Sacrifice was performed 6 or 24 h post‑CLP to evaluate the anti‑inflammatory effect of CC16. The results revealed that CC16 neutralization enhanced pro‑inflammatory CXCL1 levels, thereby confirming the anti‑inflammatory characteristics of CC16 in this model. Early CC16 neutralization immediately following TxT significantly prolonged survival within 60 h; however, the survival rate did not change until 6 days post‑trauma. Late CC16 neutralization did not provide any survival benefits. On the whole, the present study demonstrated that neutralizing CC16 confirmed its anti‑inflammatory potential in this double‑hit ALI model. Early CC16 neutralization prolonged survival within 60 h; however, no survival benefits were observed after 6 days post‑CLP in any group.

Diagnostic and prognostic roles of peripheral blood Toll-like receptor-4 and stanniocalcin-1 genes expression in acute lung injury

Acute lung injury (ALI) is an acute inflammatory disorder. Toll-like receptor-4 (TLR-4) and Stanniocalcin -1 (STC-1) had roles in lung endothelial protection. This study aims to assess TLR-4 and SCT-1 genes expressions in peripheral blood of ALI patients. Total RNA was extracted from peripheral blood of 48 subjects (20 healthy controls, 28 ALI patients) and expressions of genes were assessed by real-Time qRT-PCR. The expression levels of TLR-4 and SCT-1 genes were significantly lower in ALI patients compared to controls (P < 0.0001). After 10 days, the expression levels of TLR-4 and SCT-1 were increased compared to their baseline levels (p = 0.012 and 0.024, respectively). SCT-1 has 92.9% sensitivity and 100% specificity in ALI detection. SCT-1 gene expression was negatively correlated with severity score (r= -0.54, p = 0.003). The mortality pattern was higher in ALI patients with lower TLR-4 gene expression (p = 0.014). In conclusion, the peripheral blood expressions of TLR-4 and STC-1 genes were decreased in ALI patients. Both genes expressions were increased with patients' recovery. SCT-1 had higher sensitivity and specificity in ALI diagnosis. The peripheral blood expressions of SCT-1 and TLR-4 genes seem to be diagnostic and prognostic markers in ALI.

SU5416 attenuated lipopolysaccharide-induced acute lung injury in mice by modulating properties of vascular endothelial cells

Background and aim: A potent and selective vascular endothelial growth factor receptor (VEGFR) inhibitor SU5416, has been developed for the treatment of solid human tumors. The binding of VEGF to VEGFR plays a crucial role in the pathophysiology of respiratory disorders. However, the impact of SU5416 on lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains unclear. Thus, this study aimed to illuminate the biofunction of SU5416 in the mouse model of ALI.

Methods: Wild-type (WT) and toll-like receptor 4 (TLR4)-deficient (TLR4^−/-) C57BL/6 mice were used to establish LPS-induced ALI model. The primary pulmonary microvascular endothelial cell (PMVEC) was extracted for detection of endothelial barrier function.

Results: LPS significantly increased the number of inflammatory cells and inflammatory cytokines in bronchoalveolar lavage fluid (BALF). In addition, LPS increased alveolar epithelial cells injury, inflammation infiltration and vascular permeability of PMVEC in WT and TLR4^−/- mice. Western blotting experiment indicated VEGF/VEGFR and TLR4/NF-κB pathways were involved in the progression of LPS-stimulated ALI. Consistent with previous research, dexamethasone treatment appeared to be an effective therapeutic for mice with ALI. Moreover, treatment with SU5416 dramatically attenuated LPS-induced immune responses in mice lung tissues via inhibiting VEGF/VEGFR and TLR4/NF-κB pathways. Finally, SU5416 also decreased vascular permeability of PMVEC in vitro.

Conclusion: SU5416 ameliorated alveolar epithelial cells injury and histopathological changes in mice lung via inhibiting VEGF/VEGFR and TLR4/NF-κB signaling pathways. We also confirmed that SU5416 could restrain vascular permeability in PMVEC through improving the integrity of endothelial cell. These findings suggested that SU5416 may serve as a potential agent for the treatment of patients with ALI.

Antioxidant treatment after injury suppresses second hit immune priming

BACKGROUND

Pulmonary contusion (PC) is a common injury that often results in priming for exaggerated inflammatory responses to a second hit. Previous studies used a mouse model of pulmonary contusion and showed an early and sustained reduction of SIRT1 protein and activity in the lung and bronchoalveolar lavage (BAL) cells of injured mice. Sustained decrease in SIRT1 was associated with a primed phenotype in injured mice challenged with an inflammatory stimulus. This study tests the hypothesis that pulmonary contusion induces oxidant production that modifies and decreases SIRT1 and primes the lung for the second-hit response.

METHODS

A mouse model of pulmonary contusion was used to investigate injury-induced oxidant changes in SIRT1. Second-hit responses were evaluated by infection (Streptococcus pneumoniae) and inflammatory challenge using bacterial lipopolysaccharide. BAL, lung tissue, and blood were collected and used to evaluate inflammatory responses and SIRT1 levels, oxidant modification, and activity. Levels of NO in the BAL from mice and patients with PC were also assessed.

RESULTS

We found that oxidants produced as a result of pulmonary contusion resulted in modification of SIRT1. S-Nitrosylation was observed and correlated with increased inducible nitric oxide synthase expression after injury. Anti-oxidant treatment of injured mice preserved SIRT1 activity, decreased second hit responses and improved lung function. Elevated NO levels in the BAL of PC patients was associated with acute respiratory distress syndrome or diagnosis of pneumonia.

CONCLUSIONS

We conclude that oxidative stress in the lung after injury induces redox modification of SIRT1 and contributes to priming of the lung for a second-hit response. Antioxidant treatment suggests that SIRT1 activity after injury may be beneficial in suppressing second-hit responses.

The effect of aerosolized indomethacin on lung inflammation and injury in a rat model of blunt chest trauma

Background

Acute lung contusion from blunt chest trauma (BCT) is characterized by an intense inflammatory response in the pulmonary parenchyma, which is associated with acute lung injury (ALI), acute respiratory distress syndrome and ventilator-associated pneumonia. We hypothesized that aerosolized indomethacin may reduce pulmonary inflammation and ALI in a rat model of BCT.

Methods

Sprague-Dawley rats were anesthetized and received a tracheotomy for administration of aerosolized medication through a catheter. The BCT procedure involved free-dropping a hollow metal weight (200 g) from a height of 25.5, 38.3 or 51.2 cm onto the right thorax. We administered 1 mg/kg of indomethacin or 1 mL/kg of saline intratracheally 15 minutes after BCT. The sham group had a similar procedure without the exposure to BCT and treatment. Three hours postimpact, we obtained arterial blood gas and analyzed bronchoalveolar lavage for protein concentration, polymorphonuclear leukocytes (PMN) and cytokine levels, and lung tissue samples were taken for histopathological analysis.

Results

The rats’ mean arterial pressure and heart rate dropped immediately postimpact but recovered close to that of the sham group after 30 minutes in both control and treatment groups. Compared to BCT alone, indomethacin significantly reduced the total protein level in the lungs (1.06 ± 0.39 mg/mL v. 3.75 ± 1.95 mg/mL, p = 0.006) and alveolar FD-70 leak (0.23 ± 0.19 μg/mL v. 0.53 ± 0.19 μg/mL, p = 0.02). Indomethacin also significantly attenuated the acute inflammatory response in percent PMN (13.33 ±7.5% v. 28.0 ± 12.96%, p = 0.04). Tumour necrosis factor-α and interleukin-6 decreased in the indomethacin group, but the decreases were not significant compared with other groups.

Conclusion

Aerosolized indomethacin has a protective effect against alveloar tissue permeability and inflammatory response induced by BCT.

Neutrophils in the initiation and resolution of acute pulmonary inflammation: understanding biological function and therapeutic potential

Acute respiratory distress syndrome (ARDS) is the often fatal sequelae of a broad range of precipitating conditions. Despite decades of intensive research and clinical trials there remain no therapies in routine clinical practice that target the dysregulated and overwhelming inflammatory response that characterises ARDS. Neutrophils play a central role in the initiation, propagation and resolution of this complex inflammatory environment by migrating into the lung and executing a variety of pro-inflammatory functions. These include degranulation with liberation of bactericidal proteins, release of cytokines and reactive oxygen species as well as production of neutrophil extracellular traps. Although these functions are advantageous in clearing bacterial infection, the consequence of associated tissue damage, the contribution to worsening acute inflammation and prolonged neutrophil lifespan at sites of inflammation are deleterious. In this review, the importance of the neutrophil will be considered, together with discussion of recent advances in understanding neutrophil function and the factors that influence them throughout the phases of inflammation in ARDS. From a better understanding of neutrophils in this context, potential therapeutic targets are identified and discussed. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Pulmonary contusion

Lung contusion resulting from chest trauma may be present various clinical pictures. It quite often remains unrecognized and is only suspected later when severe complications have developed. Lung contusion may present in association with chest trauma but may also occur alone. It has to be emphasized, that lung contusion as a clinical identity does not necessarily require a blunt or penetrating chest to be in the background. Nowadays, as a result of traffic accidents, following high energy deceleration, lung contusion may present without an actual tissue damage in the chest wall as a condition initiating an independent, life-threatening generalised process. Although lung contusion shows similarities to blast injury of the lung with respect to clinical consequences, other factors play a role in its aetiology and pathology. Its description and recognition as an independent pathology is not simple. Several approaches exist: thoracic trauma, pulmonary contusion, pulmonary laceration, lung contusion; although these may show similar clinical signs, manifest in different pathologies. Pathologies with similar meaning and possibly similar clinical course cannot, actually, be differentiated; they may accompany other injuries to the trunk, skull or extremities, which, alone, are associated with high morbidity and mortality. Generally, it can be declared that besides high energy, blunt injuries affecting the trunk, lung contusion, has been an often neglected additional radiological finding attached to the main report, despite the fact, that its late consequences crucially determine the prospects of the injured.

Penehyclidine hydrochloride inhibits TLR4 signaling and inflammation, and attenuates blunt chest trauma and hemorrhagic shock-induced acute lung injury in rats

Blunt chest trauma with hemorrhagic shock (THS) frequently induces pulmonary inflammation that leads to acute lung injury (ALI). Penehyclidine hydrochloride (PHC) possesses anti‑inflammatory properties that may attenuate the systemic inflammatory response. The present study aimed to evaluate the molecular mechanism of PHC in modifying THS‑induced ALI in rats. Rats underwent either THS or a sham procedure. At 6 h subsequent to blunt chest trauma, arterial blood was drawn for blood gas and pro‑inflammatory factors analyses, and lung tissue samples were collected to examine pulmonary histopathological alterations, the wet/dry weight ratio, myeloperoxidase activity, and the protein expression levels of Toll-like receptor 4 (TLR4), phosphorylated (p‑)p38 mitogen‑activated protein kinase (MAPK), nuclear factor (NF)‑κB and activator protein‑1 (AP‑1). THS caused significant reductions in heart rate and mean arterial blood pressure, and was associated with significant increases in tumor necrosis factor‑α, interleukin (IL)‑6, IL‑1β, p‑p38MAPK, NF‑κB and AP‑1 activation, in addition to TLR4 expression, in the lung. PHC effectively attenuated THS‑induced ALI, and inhibited TLR4 expression, reduced the activation of p‑p38MAPK, NF‑κB and AP‑1, and downregulated the expression of pro‑inflammatory mediators. In conclusion, the results of the present study demonstrated that PHC may exert an anti‑inflammatory effect and attenuate THS‑induced ALI by inhibiting the TLR4 signaling pathway. These preclinical findings may offer a novel therapeutic strategy to restrict TLR4 overactivation in ALI.

Toll-Like Receptor-9 (TLR9) is Requisite for Acute Inflammatory Response and Injury Following Lung Contusion

Lung contusion (LC) is a significant risk factor for the development of acute respiratory distress syndrome. Toll-like receptor 9 (TLR9) recognizes specific unmethylated CpG motifs, which are prevalent in microbial but not vertebrate genomic DNA, leading to innate and acquired immune responses. TLR9 signaling has recently been implicated as a critical component of the inflammatory response following lung injury. The aim of the present study was to evaluate the contribution of TLR9 signaling to the acute physiologic changes following LC. Nonlethal unilateral closed-chest LC was induced in TLR9 (-/-) and wild-type (WT) mice. The mice were sacrificed at 5, 24, 48, and 72-h time points. The extent of injury was assessed by measuring bronchoalveolar lavage, cells (cytospin), albumin (permeability injury), and cytokines (inflammation). Following LC, only the TLR9 (-/-) mice showed significant reductions in the levels of albumin; release of pro-inflammatory cytokines IL-1β, IL-6, and Keratinocyte chemoattractant; production of macrophage chemoattractant protein 5; and recruitment of alveolar macrophages and neutrophil infiltration. Histological evaluation demonstrated significantly worse injury at all-time points for WT mice. Macrophages, isolated from TLR9 (-/-) mice, exhibited increased phagocytic activity at 24 h after LC compared with those isolated from WT mice. TLR9, therefore, appears to be functionally important in the development of progressive lung injury and inflammation following LC. Our findings provide a new framework for understanding the pathogenesis of lung injury and suggest blockade of TLR9 as a new therapeutic strategy for the treatment of LC-induced lung injury.

Double-Stranded RNA Interacts With Toll-Like Receptor 3 in Driving the Acute Inflammatory Response Following Lung Contusion

OBJECTIVES

Lung contusion is a major risk factor for the development of acute respiratory distress syndrome. We set to determine the role of toll-like receptor 3 and the binding of double-stranded RNA in the pathogenesis of sterile injury following lung contusion.

DESIGN

Toll-like receptor 3 expression was analyzed in postmortem lung samples from patients with lung contusion. Unilateral lung contusion was induced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-β (-/-), and wild-type mice. Subsequently, lung injury and inflammation were evaluated. Apoptotic indices, phagocytic activity, and phenotypic characterization of the macrophages were determined. Double-stranded RNA in bronchoalveolar lavage and serum samples following lung contusion was measured. A toll-like receptor 3/double-stranded RNA ligand inhibitor was injected into wild-type mice prior to lung contusion.

MEASUREMENTS AND MAIN RESULTS

Toll-like receptor 3 expression was higher in patients and wild-type mice with lung contusion. The degree of lung injury, inflammation, and macrophage apoptosis was reduced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-β (-/-), and wild-type mice with toll-like receptor 3 antibody neutralization. Alveolar macrophages from toll-like receptor 3 (-/-) mice had a lower early apoptotic index, a predominant M2 phenotype and increased surface translocation of toll-like receptor 3 from the endosome to the surface. When compared with viral activation pathways, lung injury in lung contusion demonstrated increased p38 mitogen-activated protein kinases, extracellular signal-regulated kinase 1/2 phosphorylation with inflammasome activation without a corresponding increase in nuclear factor-κB or type-1 interferon production. Additionally, pretreatment with toll-like receptor 3/double-stranded RNA ligand inhibitor led to a reduction in injury, inflammation, and macrophage apoptosis.

CONCLUSIONS

We conclude that the interaction of double-stranded RNA from injured cells with toll-like receptor 3 drives the acute inflammatory response following lung contusion.

High-Purity Magnesium Staples Suppress Inflammatory Response in Rectal Anastomoses

Magnesium-based materials are promising biodegradable implants, although the impact of magnesium on rectal anastomotic inflammation is poorly understood. Thus, we investigated the inflammatory effects of high-purity Mg staples in rectal anastomoses by in vivo luciferase reporter gene expression in transgenic mice, hematoxylin-eosin staining, immunohistochemistry, and Western blotting. As expected, strong IL-1β-mediated inflammation and inflammatory cell infiltration were observed 1 day after rectal anastomoses were stapled with high-purity Mg or Ti. However, inflammation and inflammatory cell infiltration decreased more robustly 4-7 days postoperation in tissues stapled with high-purity Mg. This rapid reduction in inflammation was confirmed by immunohistochemical analysis of IL-6 and TNF-α. Western blot also suggested that the reduced inflammatory response is due to suppressed TLR4/NF-κB signaling. In contrast, MCP-1, uPAR, and VEGF were abundantly expressed, in line with the notion that expression of these proteins is regulated by feedback between the VEGF and NF-κB pathways. In vitro expression of MCP-1, uPAR, and VEGF was also similarly high in primary rectal mucosal epithelial cells exposed to extracts from Mg staples, as measured by antibody array. Collectively, the results suggest that high-purity Mg staples suppress the inflammatory response during rectal anastomoses via TLR4/NF-κB and VEGF signaling.

Role of Complement C5 in Experimental Blunt Chest Trauma-Induced Septic Acute Lung Injury (ALI)

BACKGROUND

Severe blunt chest trauma is associated with high mortality. Sepsis represents a serious risk factor for mortality in acute respiratory distress syndrome (ARDS). In septic patients with ARDS complement activation products were found to be elevated in the plasma. In single models like LPS or trauma complement has been studied to some degree, however in clinically highly relevant double hit models such as the one used here little data is available. Here, we hypothesized that absence of C5 is correlated with a decreased inflammatory response in trauma induced septic acute lung injury.

METHODS

12 hrs after DH in mice the local and systemic cytokines and chemokines were quantified by multiplex bead array or ELISA, activated caspase-3 by western blot. Data were analyzed using one-way ANOVA followed by post-hoc Sidak's multiple comparison test (significance, p≤ 0.05).

RESULTS

In lung tissue interleukin (IL)-6, monocyte chemo attractant protein-1 (MCP-1) and granulocyte-colony stimulating factor (G-CSF) was elevated in both C5-/- mice and wildtype littermates (wt), whereas caspase-3 was reduced in lungs after DH in C5-/- mice. Systemically, reduced keratinocyte-derived chemokine (KC) levels were observed after DH in C5-/- compared to wt mice. Locally, lung myeloperoxidase (MPO), protein, IL-6, MCP-1 and G-CSF in brochoalveolar lavage fluid (BALF) were elevated after DH in C5-/- compared to wt.

CONCLUSIONS

In the complex but clinically relevant DH model the local and systemic inflammatory immune response features both, C5-dependent and C5-independent characteristics. Activation of caspase-3 in lung tissue after DH was C5-dependent whereas local inflammation in lung tissue was C5-independent.

Blunt Chest Trauma in Mice after Cigarette Smoke-Exposure: Effects of Mechanical Ventilation with 100% O2

Cigarette smoking (CS) aggravates post-traumatic acute lung injury and increases ventilator-induced lung injury due to more severe tissue inflammation and apoptosis. Hyper-inflammation after chest trauma is due to the physical damage, the drop in alveolar PO₂, and the consecutive hypoxemia and tissue hypoxia. Therefore, we tested the hypotheses that 1) CS exposure prior to blunt chest trauma causes more severe post-traumatic inflammation and thereby aggravates lung injury, and that 2) hyperoxia may attenuate this effect. Immediately after blast wave-induced blunt chest trauma, mice (n=32) with or without 3-4 weeks of CS exposure underwent 4 hours of pressure-controlled, thoraco-pulmonary compliance-titrated, lung-protective mechanical ventilation with air or 100 % O₂. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1 (HO-1), activated caspase-3, and hypoxia-inducible factor 1-α (HIF-1α) expression, nuclear factor-κB (NF-κB) activation, nitrotyrosine formation, purinergic receptor 2X₄ (P2XR₄) and 2X₇ (P2XR₇) expression, and histological scoring. CS exposure prior to chest trauma lead to higher pulmonary compliance and lower PaO₂ and Horovitz-index, associated with increased tissue IL-18 and blood MCP-1 concentrations, a 2-4-fold higher inflammatory cell infiltration, and more pronounced alveolar membrane thickening. This effect coincided with increased activated caspase-3, nitrotyrosine, P2XR₄, and P2XR₇ expression, NF-κB activation, and reduced HIF-1α expression. Hyperoxia did not further affect lung mechanics, gas exchange, pulmonary and systemic cytokine and chemokine concentrations, or histological scoring, except for some patchy alveolar edema in CS exposed mice. However, hyperoxia attenuated tissue HIF-1α, nitrotyrosine, P2XR₇, and P2XR₄ expression, while it increased HO-1 formation in CS exposed mice. Overall, CS exposure aggravated post-traumatic inflammation, nitrosative stress and thereby organ dysfunction and injury; short-term, lung-protective, hyperoxic mechanical ventilation have no major beneficial effect despite attenuation of nitrosative stress, possibly due to compensation of by regional alveolar hypoxia and/or consecutive hypoxemia, resulting in down-regulation of HIF-1α expression.

SIRT1 mediates a primed response to immune challenge after traumatic lung injury

BACKGROUND

Pulmonary contusion (PC) is a common, potentially lethal injury that results in priming for exaggerated inflammatory responses to subsequent immune challenge like infection (second hit). The molecular mechanism of priming and the second hit phenomenon after PC remain obscure. With the use of a mouse model of PC, this study explores the role of sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, in priming for a second hit after injury.

METHODS

With the use of a mouse model of PC, injury-primed second-hit host responses were tested at 24 hours after PC by (1) in vivo infectious challenge of injured mice or (2) ex vivo inflammatory challenge of isolated immune cells from injured mice. SIRT activators or repressors were used to test for SIRT1 participation in these second-hit responses.

RESULTS

PC-injured mice given an in vivo infectious challenge by cecal ligation and puncture (CLP) had significantly increased mortality compared with injury or infectious challenge alone. Isolated bronchoalveolar lavage (BAL) cells from injured mice given an ex vivo inflammatory challenge with bacterial lipopolysaccharide (LPS) had increased levels of tumor necrosis factor α messenger RNA compared with uninjured mice. We found that PC reduced SIRT1 protein, messenger RNA, and SIRT1 enzymatic activity in injured lung tissue. We also found decreased SIRT1 protein levels in BAL cells from injured mice. We further found that injured mice treated with a SIRT1 activator, resveratrol, showed significantly decreased polymorphonuclear leukocytes (PMN) in the BAL in response to intratracheal LPS and increased survival from CLP.

CONCLUSION

These results showed that PC decreased SIRT1 levels in the lung correlated with enhanced responses to infectious or inflammatory stimuli in injured mice. Treatment of injured mice with a SIRT1 activator, resveratrol, decreased LPS inflammatory response and increased survival after CLP. Our results suggest that SIRT1 participates in the second-hit response after injury.

Roles of lipoxin A4 receptor activation and anti-interleukin-1β antibody on the toll-like receptor 2/mycloid differentiation factor 88/nuclear factor-κB pathway in airway inflammation induced by ovalbumin

Previous studies investigating the role of toll-like receptors (TLRs) in asthma have been inconclusive. It has remained elusive whether the toll-like receptors (TLR2)/mycloid differentiation factor 88 (MyD88)/nuclear factor (NF)-κB signaling pathway is involved in lipoxin A4 (LXA4)-induced protection against asthma. Therefore, the present study investigated whether ovalbumin (OVA)-induced airway inflammation is mediated by upregulation of the TLR2/MyD88/NF-κB signaling pathway, and whether it proceeds via the inhibition of the activation of the LXA4 receptor and anti-interleukin (IL)-1β antibodies. Mice with airway inflammation induced by OVA administration were treated with or without a LXA4 receptor agonist, BML-111 and anti-IL-1β antibody. Serum levels of IL-1β, IL-4, IL-8 and interferon-γ (IFN-γ) were assessed, and levels of IL-1β, IL-4, IL-8 and OVA-immunoglobulin (Ig)E, as well as leukocyte counts in the bronchoalveolar lavage fluid (BALF) were measured. Pathological features and expression of TLR2, MyD88 and NF-κB in the lungs were analyzed. Expression of TLR2 and MyD88, and activation of NF-κB in leukocytes as well as levels of IL-4, IL-6 and IL-8 released from leukocytes exposed to IL-1β were assessed. OVA treatment increased the levels of IL-1β, IL-4 and IL-8 in the serum and BLAF, the number of leukocytes and the levels of OVA-IgE in the BALF, the expression of TLR2 and MyD88, and the activation of NF-κB in the lung. These increments induced by OVA were inhibited by treatment with BML-111 and anti-IL-1β antibodies. Treatment of the leukocytes with BML-111 or TLR2 antibody, or MyD88 or NF-κB inhibitor, all blocked the IL-1β-triggered production of IL-4, IL-6 and IL-8 and activation of NF-κB. Treatment of the leukocytes with BML-111 or TLR2 antibody suppressed IL-1β-induced TLR2 and MyD88 expression. The present study therefore suggested that OVA-induced airway inflammation is mediated by the TLR2/MyD88/NF-κB pathway. IL-1β has a pivotal role in the airway inflammation and upregulation of the TLR2/MyD88/NF-κB pathway induced by OVA. BML-111 and anti-IL-1β antibody restrains the OVA-induced airway inflammation via downregulation of the TLR2/MyD88/NF-κB pathway.

Toll-like receptor 4 implicated in acute lung injury induced by paraquat poisoning in mice

OBJECTIVE

To investigate the possible relationship and mechanism of Toll-like receptor 4 (TLR4) and acute lung injury induced by paraquat (PQ) poisoning.

METHODS

Male wild type mice and male TLR4-knockout mice were used in this study. After paraquat treatment for 24 hours, mice were euthanized and pathology, TLR4 expression and pro-inflammatory cytokines were evaluated.

RESULTS

Wild type mice showed deteriorated lung injury, pathological damages and increased TLR4 expression and pulmonary TNF-α, IL-1β and NF-κB p65 levels after PQ treatment. TLR4-deficient mice were significantly resistant to paraquat-induced lung injury.

CONCLUSION

TLR4 may be required as a mediator and may play an important role in acute lung injury induced by paraquat.

Complement mediates a primed inflammatory response after traumatic lung injury

BACKGROUND

Pulmonary contusion (PC) is a common, potentially lethal injury that results in the priming for exaggerated responses to subsequent immune challenge such as an infection (second hit). We hypothesize a PC-induced complement (C) activation participates in the priming effect for a second hit.

METHODS

Male, 8 weeks to 9 weeks, C57BL/6 mice (wild-type, C5) underwent blunt chest trauma resulting in PC. At 3 hours/24 hours after injury, the inflammatory response was measured in tissue, serum, and bronchoalveolar lavage (BAL). The thrombin inhibitor, hirudin, was used to determine if injury-induced thrombin participated in the activation of C. Injury-primed responses were tested by challenging injured mice with bacterial endotoxin (lipopolysaccharide, LPS) as a second hit. Inflammatory responses were assessed at 4 hours after LPS challenge. Data were analyzed using one-way analysis of variance with Bonferroni multiple comparison posttest (significance, p ≤ 0.05). Protocols were approved by the Institutional Animal Care and Use Committee.

RESULTS

We found significantly increased levels of C5a in the BAL of injured animals as early as 24 hours, persisting for up to 72 hours after injury. Hirudin-treated injured mice had significantly decreased levels of thrombin in the BAL that correlated with reduced C5a levels. Injured mice challenged with intratracheal (IT) LPS had increased C5a and inflammatory response. Conversely, inhibition of C5a or its receptor, C5aR, before LPS challenge correlated with decreased inflammatory responses; C5a-deficient mice showed a similar loss of primed response to LPS challenge.

CONCLUSION

Complement C5a levels in the BAL are increased over several days after PC. Premorbid inhibition of thrombin markedly decreases C5a levels after PC, suggesting that thrombin-induced C activation is the major pathway of activation after PC. Similarly, inhibition of C5a after PC will decrease injury-primed responses to LPS stimulation. Our findings suggest cross-talk between the coagulation and complement systems that induce immune priming after PC.

The activins and their binding protein, follistatin-Diagnostic and therapeutic targets in inflammatory disease and fibrosis

The activins, as members of the transforming growth factor-β superfamily, are pleiotrophic regulators of cell development and function, including cells of the myeloid and lymphoid lineages. Clinical and animal studies have shown that activin levels increase in both acute and chronic inflammation, and are frequently indicators of disease severity. Moreover, inhibition of activin action can reduce inflammation, damage, fibrosis and morbidity/mortality in various disease models. Consequently, activin A and, more recently, activin B are emerging as important diagnostic tools and therapeutic targets in inflammatory and fibrotic diseases. Activin antagonists such as follistatin, an endogenous activin-binding protein, offer considerable promise as therapies in conditions as diverse as sepsis, liver fibrosis, acute lung injury, asthma, wound healing and ischaemia-reperfusion injury.

Mechanical ventilation increases the inflammatory response induced by lung contusion

BACKGROUND

Posttraumatic lung contusion is common after blunt chest trauma, and patients often need ventilatory support. Lung contusion induces an inflammatory response signified by primed polymorph neutrophil granulocytes (PMNs) in blood and tissue. Mechanical ventilation (MV) can also cause an inflammatory response. The aim of this study was to develop an animal model to investigate the effect of high-volume ventilation on the inflammatory response in blunt chest trauma.

MATERIALS AND METHODS

We assigned 23 male Sprague-Dawley rats to either MV or bilateral lung contusion followed by MV. We used three extra rats as controls. Lung contusion was induced by a blast generator, a device releasing a single pressure blast wave centered on the chest. We determined tissue and systemic inflammation by absolute PMN numbers in blood and bronchoalveolar lavage fluid (BALF), myeloperoxidase, interleukin (IL)-6, IL 1β, growth-related oncogene-KC, and IL-10 in both plasma and BALF.

RESULTS

Survival after blunt chest trauma was correlated to the distance to the blast generator. Compared with controls, both MV and blast plus MV rats showed increased systemic and pulmonary inflammation, expressed by higher PMNs, myeloperoxidase levels, and cytokine levels in both blood and BALF. Blast plus MV rats showed a higher systemic and pulmonary inflammatory response than MV rats.

CONCLUSIONS

The blast generator generated reproducible blunt chest trauma in rats. Mechanical ventilation after lung contusion induced a larger overall inflammatory response than MV alone, which indicates that local damage contributes not only to local inflammation, but also to systemic inflammation. This emphasizes the importance of lung protective ventilation strategies after pulmonary contusion.

Management of pulmonary contusion and flail chest: an Eastern Association for the Surgery of Trauma practice management guideline

BACKGROUND

Despite the prevalence and recognized association of pulmonary contusion and flail chest (PC-FC) as a combined, complex injury pattern with interrelated pathophysiology, the mortality and morbidity of this entity have not improved during the last three decades. The purpose of this updated EAST practice management guideline was to present evidence-based recommendations for the treatment of PC-FC.

METHODS

A query was conducted of MEDLINE, Embase, PubMed and Cochrane databases for the period from January 1966 through June 30, 2011. All evidence was reviewed and graded by two members of the guideline committee. Guideline formulation was performed by committee consensus.

RESULTS

Of the 215 articles identified in the search, 129 were deemed appropriate for review, grading, and inclusion in the guideline. This practice management guideline has a total of six Level 2 and eight Level 3 recommendations.

CONCLUSION

Patients with PC-FC should not be excessively fluid restricted but should be resuscitated to maintain signs of adequate tissue perfusion. Obligatory mechanical ventilation in the absence of respiratory failure should be avoided. The use of optimal analgesia and aggressive chest physiotherapy should be applied to minimize the likelihood of respiratory failure. Epidural catheter is the preferred mode of analgesia delivery in severe flail chest injury. Paravertebral analgesia may be equivalent to epidural analgesia and may be appropriate in certain situations when epidural is contraindicated.A trial of mask continuous positive airway pressure should be considered in alert patients with marginal respiratory status. Patients requiring mechanical ventilation should be supported in a manner based on institutional and physician preference and separated from the ventilator at the earliest possible time. Positive end-expiratory pressure or continuous positive airway pressure should be provided. High-frequency oscillatory ventilation should be considered for patients failing conventional ventilatory modes. Independent lung ventilation may also be considered in severe unilateral pulmonary contusion when shunt cannot be otherwise corrected.Surgical fixation of flail chest may be considered in cases of severe flail chest failing to wean from the ventilator or when thoracotomy is required for other reasons. Self-activating multidisciplinary protocols for the treatment of chest wall injuries may improve outcome and should be considered where feasible.Steroids should not be used in the therapy of pulmonary contusion. Diuretics may be used in the setting of hydrostatic fluid overload in hemodynamically stable patients or in the setting of known concurrent congestive heart failure.

Lung Contusion: A Clinico-Pathological Entity with Unpredictable Clinical Course

Lung contusion is an entity involving injury to the alveolar capillaries, without any tear or cut in the lung tissue. This results in accumulation of blood and other fluids within the lung tissue. The excess fluid interferes with gas exchange leading to hypoxia. The pathophysiology of lung contusion includes ventilation/perfusion mismatching, increased intrapulmonary shunting, increased lung water, segmental lung damage, and a loss of compliance. Clinically, patient's presents with hypoxiemia, hypercarbia and increase in laboured breathing. Patients are treated with supplemental oxygen and mechanical ventilation whenever indicated. Treatment is primarily supportive. Computed tomography (CT) is very sensitive for diagnosing pulmonary contusion. Pulmonary contusion occurs in 25-35% of all blunt chest traumas.

Investigation of pulmonary contusion extent and its correlation to crash, occupant, and injury characteristics in motor vehicle crashes

BACKGROUND

Pulmonary contusion (PC) is a leading injury in blunt chest trauma and is most commonly caused by motor vehicle crashes (MVC). To improve understanding of the relationship between insult and outcome, this study relates PC severity to crash, occupant, and injury parameters in MVCs.

METHODS

Twenty-nine subjects with PC were selected from the Crash Injury Research and Engineering Network (CIREN) database, which contains detailed crash and medical information on MVC occupants. Computed tomography scans of these subjects were segmented using a semi-automated protocol to quantify the volumetric percentage of injured tissue in each lung. Techniques were used to quantify the geometry and location of PC, as well as the location of rib fractures. Injury extent including percent PC volume and the number of rib fractures was analyzed and its relation to crash and occupant characteristics was explored.

RESULTS

Frontal and near-side crashes composed 72% of the dataset and the near-side door was the component most often associated with PC causation. The number of rib fractures increased with age and fracture patterns varied with crash type. In near-side crashes, occupant weight and BMI were positively correlated with percent PC volume and the number of rib fractures, and the impact severity was positively correlated with percent PC volume in the lung nearest the impact.

CONCLUSIONS

This study quantified PC morphology in 29 MVC occupants and examined the relationship between injury severity and crash and occupant parameters to better characterize the mechanism of injury. The results of this study may contribute to the prevention, mitigation, and treatment of PC.

In vivo transfection of nuclear factor κB decoy protects pulmonary function against acute lung contusion in rabbits

BACKGROUND

The transcription factor nuclear factor κB (NF-κB) regulates the expression of numerous proinflammatory factors that may exacerbate the response to acute injury. We investigated the effect of an inhibitory NF-κB decoy oligodeoxynucleotide on proinflammatory factor expression and pulmonary function after acute lung contusion in rabbits.

METHODS

Thirty-minutes after acute lung contusion, the NF-κB decoy or a scrambled control oligodeoxynucleotide was injected via the jugular vein. Blood samples were collected for blood gas analysis and plasma tumor necrosis factor α, interleukin 1β (IL-1β), IL-13, and IL-10 were measured by enzyme-linked immunosorbent assay at 1, 2, 3, and 4 hours after contusion. In addition, NF-κB protein expression in lung tissue was detected by Western blot analysis.

RESULTS

The blood PO2 decreased immediately after lung contusion, whereas PAO2 increased significantly, indicative of disrupted respiratory function. Respiratory function improved after sense NF-κB decoy injection but not after injection of the inactive scrambled form. Injection of NF-κB decoy resulted in significant inhibition of NF-κB protein expression in lung tissue and a reduction in the serum concentrations of proinflammatory cytokines tumor necrosis factor α and IL-1β compared with those of control rabbits injected with the scrambled decoy. In contrast, serum levels of the anti-inflammatory cytokines IL-10 and IL-13 increased after decoy injection compared with those of control animals and rabbits injected with the scrambled decoy.

CONCLUSION

The sense NF-κB decoy protected respiratory function and reduced serum proinflammatory factor secretion after acute lung contusion. Inhibition of NF-κB may allow for preservation of pulmonary function for patients with acute lung injury.

Innate immune response to pulmonary contusion: identification of cell type-specific inflammatory responses

Lung injury from pulmonary contusion is a common traumatic injury, predominantly seen after blunt chest trauma, such as in vehicular accidents. The local and systemic inflammatory response to injury includes activation of innate immune receptors, elaboration of a variety of inflammatory mediators, and recruitment of inflammatory cells to the injured lung. Using a mouse model of pulmonary contusion, we had previously shown that innate immune Toll-like receptors 2 and 4 (TLR2 and TLR4) mediate the inflammatory response to lung injury. In this study, we used chimeric mice generated by adoptive bone marrow transfer between TLR2 or TLR4 and wild-type mice. We found that, in the lung, both bone marrow-derived and nonmyeloid cells contribute to TLR-dependent inflammatory responses after injury in a cell type-specific manner. We also show a novel TLR2-dependent injury mechanism that is associated with enhanced airway epithelial cell apoptosis and increased pulmonary FasL and Fas expression in the lungs from injured mice. Thus, in addition to cardiopulmonary physiological dysfunction, cell type-specific TLR and their differential response to injury may provide novel specific targets for management of patients with pulmonary contusion.

Host susceptibility to gram-negative pneumonia after lung contusion

BACKGROUND

Lung contusion (LC) induces inflammation with high local concentrations of proinflammatory mediators stimulating chemotaxis and activation of neutrophils. LC is also a risk factor for development of pneumonia; however, the reason for this increased susceptibility is not clearly identified. We hypothesize that LC creates acute changes in the host pulmonary innate immune system that leads to vulnerability from a "second" hit bacterial infection.

METHODS

Female C57Bl/6 mice underwent LC injury at time -6 hours. At 0 hours, these mice were inoculated intratracheally with 1,000 colony forming unit (CFU) of Klebsiella pneumoniae (LC+Pneu) or vehicle (LC). Control animals underwent a sham LC injury followed by pneumonia (Sham+Pneu). Bronchoalveolar lavage (BAL) fluid and lung tissue specimens were collected. Lung bacteria levels were quantified by serial dilution, plating, and counting CFUs. Cytokine levels were assayed by ELISA. Cell type identification and quantification was performed using flow cytometry.

RESULTS

Survival at 72 hours was markedly different for the LC, Sham+Pneu, and LC+Pneu groups (100%, 80%, 20%, p < 0.05 Sham+Pneu vs. LC+Pneu). LC+Pneu animals had decreased pulmonary bacterial clearance at 24 hours compared with the Sham+Pneu group (4 × 10(7) vs. 8 × 10(6) CFUs, p < 0.05). BAL levels of IL-1β, IL-6, and keratinocyte chemoattractant were all significantly elevated in LC+Pneu mice compared with the Sham+Pneu group at 24 hours. Conversely, the Sham+Pneu mice had increased levels of macrophage inflammatory protein-2, total cells, macrophages, and neutrophils in BAL compared with the LC+Pneu group at 24 hours. LC+Pneu animals demonstrated changes in macrophage apoptosis and necrosis in BAL samples obtained 2 hours after induction of pneumonia when compared with the Sham+Pneu group. Both Sham+Pneu and LC+Pneu animals demonstrated an increase in the level of IL-10 in BAL fluid compared with LC animals.

CONCLUSION

Acute inflammation after LC acts to modulate the presence of inflammatory cells necessary to combat gram-negative bacteria. This results in decreased bacterial clearance and increased mortality from pneumonia.

Electroporation-mediated in vivo gene delivery of the Na+/K+-ATPase pump reduced lung injury in a mouse model of lung contusion

BACKGROUND

Lung contusion (LC) is an independent risk factor for acute respiratory distress syndrome. The final common pathway in ARDS involves accumulation of fluid in the alveoli. In this study, we demonstrate the application of a potential gene therapy approach by delivering the Na+/K+-ATPase pump subunits in a murine model of LC. We hypothesized that restoring the activity of the pump will result in removal of excess alveolar fluid and additionally reduce inflammation.

METHODS

Under anesthesia, C57/BL6 mice were struck along the right posterior axillary line 1 cm above the costal margin with a cortical contusion impactor. Immediately afterward, 100 μg of plasmid DNA coding for the α,β of the Na+/K+-ATPase pump were instilled into the lungs (LC-electroporation-pump group). Contusion only (LC-only) and a sham saline instillation group after contusion were used as controls (LC-electroporation-sham). By using a BTX 830 electroporator, eight electrical pulses of 200 V/cm field strength were applied transthoracically. Mice were killed at 24 hours, 48 hours, and 72 hours after delivery. Bronchial alveolar lavage was recollected to measure albumin and cytokines by enzyme-linked immunosorbent assay. Pulmonary compliance was measured, and lungs were subject to histopathologic analysis.

RESULTS

After the electroporation and delivery of genes coding for the α,β subunits of the Na+/K+-ATPase pump, there was a significant mitigation of acute lung injury as evidenced by reduction in bronchial alveolar lavage levels of albumin, improved pressure volume curves, and reduced inflammation seen on histology.

CONCLUSION

Electroporation-mediated gene transfer of the subunits of the Na+/K+-ATPase pump enhanced recovery from acute inflammatory lung injury after LC.

Effects of penehyclidine hydrochloride on pulmonary contusion from blunt chest trauma in rats

BACKGROUND AND OBJECTIVE

Toll-like receptor 4 (TLR4) is widely recognised as a pattern recognition receptor (PRR) in the triggering of innate immunity. Lung inflammation and systemic innate immune responses are dependent on TLR4 activation undergoing pulmonary contusion. Therefore, the author investigated the effects of penehyclidine hydrochloride (PHC) on the expression of TLR4 and inflammatory responses of blunt chest trauma-induced pulmonary contusion.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats were randomly assigned into three groups: normal control (NC) group, pulmonary contusion (PC) group and penehyclidine hydrochloride treatment (PHC) group. Pulmonary contusion was induced in anesthetised rats at fixed chest impact energy of 2.45J. Lung injury was assessed by the histopathology changes, arterial blood gas and myeloperoxidase (MPO) activity of lung. The serum tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured using enzyme-linked immunosorbent assays (ELISA). The expression of TLR4 was determined by immunohistochemistry.

RESULTS

Blunt chest trauma produced leucocytosis in the interstitial capillaries, hypoxemia, and increased MPO activity. The expressions of TNF-α, IL-6 and TLR4 in the lung were significantly enhanced during pulmonary contusion. PHC treatments effectively attenuated pulmonary inflammation responses, as shown by improved pulmonary oxygenation, histopathology damage, decreased the MPO activity, the expressions of TNF-α, IL-6, and TLR4 after lung injury.

CONCLUSION

It might be concluded that PHC exhibit anti-inflammatory and protective effects in traumatic lung injury via the inhibition of the TLR4 pathway.

Role of macrophage chemoattractant protein-1 in acute inflammation after lung contusion

Lung contusion (LC), commonly observed in patients with thoracic trauma is a leading risk factor for development of acute lung injury/acute respiratory distress syndrome. Previously, we have shown that CC chemokine ligand (CCL)-2, a monotactic chemokine abundant in the lungs, is significantly elevated in LC. This study investigated the nature of protection afforded by CCL-2 in acute lung injury/acute respiratory distress syndrome during LC, using rats and CC chemokine receptor (CCR) 2 knockout (CCR2(-/-)) mice. Rats injected with a polyclonal antibody to CCL-2 showed higher levels of albumin and IL-6 in the bronchoalveolar lavage and myeloperoxidase in the lung tissue after LC. Closed-chest bilateral LC demonstrated CCL-2 localization in alveolar macrophages (AMs) and epithelial cells. Subsequent experiments performed using a murine model of LC showed that the extent of injury, assessed by pulmonary compliance and albumin levels in the bronchoalveolar lavage, was higher in the CCR2(-/-) mice when compared with the wild-type (WT) mice. We also found increased release of IL-1β, IL-6, macrophage inflammatory protein-1, and keratinocyte chemoattractant, lower recruitment of AMs, and higher neutrophil infiltration and phagocytic activity in CCR2(-/-) mice at 24 hours. However, impaired phagocytic activity was observed at 48 hours compared with the WT. Production of CCL-2 and macrophage chemoattractant protein-5 was increased in the absence of CCR2, thus suggesting a negative feedback mechanism of regulation. Isolated AMs in the CCR2(-/-) mice showed a predominant M1 phenotype compared with the predominant M2 phenotype in WT mice. Taken together, the above results show that CCL-2 is functionally important in the down-modulation of injury and inflammation in LC.

Type I interferon signaling regulates the composition of inflammatory infiltrates upon infection with Listeria monocytogenes

Type I IFN is key to the immune response to viral pathogens, however its role in bacterial infections is less well understood. Mice lacking the type I IFN receptor (IFNAR-/-) demonstrate enhanced resistance to infection with Listeriamonocytogenes. We have now determined that following infection with Listeria, the composition of innate cells recruited to the peritoneal cavity of IFNAR-/- mice reflects an increase in the frequency of neutrophils and a decrease in monocyte frequency compared to WT controls. These differences in inflammatory infiltrates could not be attributed to distinct bone marrow composition prior to infection or to level of apoptosis. We also observed no differences in neutrophil oxidative burst. However, blocking CXCR2 prevented enhanced neutrophil influx and hampered bacterial clearance. Taken together, these studies highlight a novel mechanism by which type I interferon signaling regulates the immune response to Listeria, through negative regulation of chemokines driving neutrophil recruitment.

Burn-induced acute lung injury requires a functional Toll-like receptor 4

The role of the Toll-like receptor 4 (TLR4), a component of the innate immune system, in the development of burn-induced acute lung injury (ALI) has not been completely defined. Recent data suggested that an intact TLR4 plays a major role in the development of organ injury in sterile inflammation. We hypothesized that burn-induced ALI is a TLR4-dependent process. Male C57BL/6J (TLR4 wild-type [WT]) and C57BL/10ScN (TLR4 knockout [KO]) mice were subjected to a 30% total body surface area steam burn. Animals were killed at 6 and 24 h after the insult. Lung specimens were harvested for histological examination after hematoxylin-eosin staining. In addition, lung myeloperoxidase (MPO) and intercellular adhesion molecule 1 immunostaining was performed. Lung MPO was measured by an enzymatic assay. Total lung keratinocyte-derived chemoattractant (IL-8) content was measured by enzyme-linked immunosorbent assay. Western blot was performed to quantify phosphorylated IκBα, phosphorylated nuclear factor κB p65 (NF-κBp65), and high mobility group box 1 expression. Acute lung injury, characterized by thickening of the alveolar-capillary membrane, hyaline membrane formation, intraalveolar hemorrhage, and neutrophil infiltration, was seen in WT but not KO animals at 24 h. Myeloperoxidase and intercellular adhesion molecule 1 immunostaining of KO animals was also similar to sham but elevated in WT animals. In addition, a reduction in MPO enzymatic activity was observed in KO mice as well as a reduction in IL-8 levels compared with their WT counterparts. Burn-induced ALI develops within 24 h after the initial thermal insult in our model. Toll-like receptor 4 KO animals were clearly protected and had a much less severe lung injury. Our data suggest that burn-induced ALI is a TLR4-dependent process.

Mechanism of neutrophil recruitment to the lung after pulmonary contusion

Blunt chest trauma resulting in pulmonary contusion is a common but poorly understood injury. We previously demonstrated that lung contusion activates localized and systemic innate immune mechanisms and recruits neutrophils to the injured lung. We hypothesized that the innate immune and inflammatory activation of neutrophils may figure prominently in the response to lung injury. To investigate this, we used a model of pulmonary contusion in the mouse that is similar to that observed clinically in humans and evaluated postinjury lung function and pulmonary neutrophil recruitment. Comparisons were made between injured mice with and without neutrophil depletion. We further examined the role of chemokines and adhesion receptors in neutrophil recruitment to the injured lung. We found that lung injury and resultant physiological dysfunction after contusion were dependent on the presence of neutrophils in the alveolar space. We show that CXCL1, CXCL2/3, and CXCR2 are involved in neutrophil recruitment to the lung after injury and that intercellular adhesion molecule 1 is locally expressed and actively participates in this process. Injured gp91-deficient mice showed improved lung function, indicating that oxidant production by neutrophil NADPH oxidase mediates lung dysfunction after contusion. These data suggest that both neutrophil presence and function are required for lung injury after lung contusion.

Pseudofracture: an acute peripheral tissue trauma model

Following trauma there is an early hyper-reactive inflammatory response that can lead to multiple organ dysfunction and high mortality in trauma patients; this response is often accompanied by a delayed immunosuppression that adds the clinical complications of infection and can also increase mortality. Many studies have begun to assess these changes in the reactivity of the immune system following trauma. Immunologic studies are greatly supported through the wide variety of transgenic and knockout mice available for in vivo modeling; these strains aid in detailed investigations to assess the molecular pathways involved in the immunologic responses. The challenge in experimental murine trauma modeling is long term investigation, as fracture fixation techniques in mice, can be complex and not easily reproducible. This pseudofracture model, an easily reproduced trauma model, overcomes these difficulties by immunologically mimicking an extremity fracture environment, while allowing freedom of movement in the animals and long term survival without the continual, prolonged use of anaesthesia. The intent is to recreate the features of long bone fracture; injured muscle and soft tissue are exposed to damaged bone and bone marrow without breaking the native bone. The pseudofracture model consists of two parts: a bilateral muscle crush injury to the hindlimbs, followed by injection of a bone solution into these injured muscles. The bone solution is prepared by harvesting the long bones from both hindlimbs of an age- and weight-matched syngeneic donor. These bones are then crushed and resuspended in phosphate buffered saline to create the bone solution. Bilateral femur fracture is a commonly used and well-established model of extremity trauma, and was the comparative model during the development of the pseudofracture model. Among the variety of available fracture models, we chose to use a closed method of fracture with soft tissue injury as our comparison to the pseudofracture, as we wanted a sterile yet proportionally severe peripheral tissue trauma model. Hemorrhagic shock is a common finding in the setting of severe trauma, and the global hypoperfusion adds a very relevant element to a trauma model. The pseudofracture model can be easily combined with a hemorrhagic shock model for a multiple trauma model of high severity.

Toll-like receptor signaling pathways and the evidence linking toll-like receptor signaling to cardiac ischemia/reperfusion injury

Toll-like receptors (TLRs) play a key role in innate immune defenses. After activation by foreign pathogens or host-derived molecules, TLRs signal via overlapping or distinct signaling cascades and eventually induce numerous genes involved in a variety of cellular responses. A growing body of evidence suggests that TLR signaling also plays an important role in cardiac ischemia/reperfusion injury. We review our current understanding of the TLR signaling pathways and their roles in the pathophysiology of cardiac ischemia/reperfusion injury, as well as discuss several mechanisms for TLR activation and regulation.

The role of toll-like receptors in acute and chronic lung inflammation

By virtue of its direct contact with the environment, the lung is constantly challenged by infectious and non-infectious stimuli that necessitate a robust yet highly controlled host response coordinated by the innate and adaptive arms of the immune system. Mammalian Toll-like receptors (TLRs) function as crucial sentinels of microbial and non-infectious antigens throughout the respiratory tract and mediate host innate immunity. Selective induction of inflammatory responses to harmful environmental exposures and tolerance to innocuous antigens are required to maintain tissue homeostasis and integrity. Conversely, dysregulated innate immune responses manifest as sustained and self-perpetuating tissue damage rather than controlled tissue repair. In this article we review aspects of Toll-like receptor function that are relevant to the development of acute lung injury and chronic obstructive lung diseases as well as resistance to frequently associated microbial infections.

Major stress hormones suppress the response of macrophages through down-regulation of TLR2 and TLR4

BACKGROUND

Severe trauma often leads to diminished cytokines especially from macrophages to Toll-like receptor (TLR) agonists. However, the molecular mechanisms remain to be elucidated. As surgical trauma could also induce neuroendocrine hormones to modulate the immune system, we investigated the effects of major hormones, including endogenous glucocorticoid (corticosterone (CORT)), epinephrine (E), and norepinephrine (NE) on the expression and response of TLR2 and TLR4 in macrophages.

MATERIALS AND METHODS

Rat macrophages were pretreated by each hormone (1000 ng/mL of CORT, E, and NE) for 24 h, then restimulated with Pam3CSK4 or lipopolysaccharide (LPS) for further 24 h, and supernatant tumor necrosis factor-alpha (TNF-α) was measured. Additionally, macrophages were incubated with different concentrations of hormones (0-10,000 ng/mL) for 48 h or with 1000 ng/mL of hormones for 0-48 h, the expressions of TLR2 and TLR4 and intracellular molecules (MyD88, IRAK1, and TRAF6) in macrophages were analyzed by real-time quantitative polymerase chain reaction (PCR) and RT-PCR, respectively.

RESULTS

Pam3CSK4-stimulated TNF-α production was significantly reduced from macrophages pretreated with CORT, and both Pam3CSK4- and LPS-stimulated TNF-α were suppressed with E. Moreover, CORT down-regulated only TLR2 expression in both time- and dose-dependent manner, but both TLR2 and TLR4 mRNA expressions were down-regulated in time- and dose-dependent manner after exposure to E. However, the transcript expression of MyD88, IRAK1, and TRAF6 remained unchanged after exposure to each hormone.

CONCLUSIONS

These results suggested that the down-regulation of TLR2 and TLR4 expressions by CORT and E is involved in the hyporesponsiveness of macrophages.

Decreased pulmonary inflammation following ethanol and burn injury in mice deficient in TLR4 but not TLR2 signaling

BACKGROUND

Clinical and laboratory evidence suggests that alcohol consumption prior to burn injury leads to dysregulated immune function and subsequent higher rates of morbidity and mortality. Our laboratory previously observed higher levels of pro-inflammatory cytokines and leukocyte infiltration in the lungs of mice following ethanol and burn injury. To understand the mechanism of the increased inflammatory response, we looked at different signaling initiators of inflammation including toll-like receptors 2 and 4 (TLR2 and 4) pathways.

METHODS

Wild-type, TLR2, and TLR4 knockout mice were treated with vehicle or a single binge dose of ethanol (1.11 g/kg) and subsequently given a sham or burn injury. Twenty-four hours postinjury, systemic and pulmonary levels of pro-inflammatory cytokines were quantified, and differences in neutrophil infiltration were determined by histological examination.

RESULTS

Higher numbers of neutrophils were observed in the lungs of wild-type mice following the combined insult of ethanol and burn injury relative to either injury alone. This increase in leukocyte accumulation was absent in the TLR4 knockout mice. Circulating levels of IL-6 and tumor necrosis factor-α were also elevated in wild-type mice but not in TLR4 knockout mice. Consistent with these findings, pulmonary levels of KC and IL-6 were increased in wild-type mice following burn and ethanol compared to burn injury alone as well as to their TLR4 knockout counterparts. In contrast, TLR2 knockout mice displayed similar levels, to wild-type mice, of neutrophil infiltration as well as IL-6 and KC in the lung.

CONCLUSIONS

These data suggest that TLR4 signaling is a crucial contributory component in the exuberant inflammation after ethanol and burn injury. However, TLR2 does not appear to play a vital role in the aberrant pulmonary inflammation.

Toll-like receptor-4 mediates intestinal barrier breakdown after thermal injury

OBJECTIVE

Toll-like receptor 4 (TLR-4) activation after sterile injury leads to organ dysfunction at distant sites. We have shown previously that intestinal barrier breakdown and alteration of tight junction proteins follows thermal injury; however, the role of TLR-4 in this process remains unclear. We hypothesized that increased intestinal permeability and barrier breakdown after burns is a TLR-4 dependent process; hence, knocking down the TLR-4 gene would have a protective effect on burn-induced intestinal dysfunction.

METHODS

Male C57BL/6J (TLR-4 wild type [WT]) and C57BL/10ScN (TLR-4 knockout [KO]) mice were assigned randomly to either 30% total body surface area steam burn or sham injury. At 4 h, permeability to intraluminally administered fluorescein isothiocyanate (FITC)-dextran was assessed by measuring the fluorescence of the serum. Intestinal samples were analyzed for the presence of the tight junction protein occludin by immunoblotting and immunohistochemistry. Tumor necrosis factor (TNF)-alpha concentrations in the serum and intestines were measured by enzyme-linked immunosorbent assay at 2 h post-burn.

RESULTS

Serum concentrations of FITC-dextran were decreased in TLR-4 KO mice compared with TLR-4 WT mice after burn injury (92.0 micrograms/mL and 264.5 micrograms/mL, respectively; p < 0.05). After injury, no difference in intestinal permeability was observed between the TLR-4 KO mice and the TLR-4 WT sham-treated mice. The TLR-4 KO mice had preservation of occludin concentrations after thermal injury in both immunoblot and immunohistochemistry assays, but concentrations were decreased in TLR-4 WT animals. The serum concentrations of TNF-alpha serum were higher in TLR-4 WT burned animals than in the sham-treated mice. The TLR-4 KO animals had unmeasurable concentrations of TNF-alpha. No differences in TNF-alpha were observed in the intestinal tissue at 2 h.

CONCLUSIONS

Mice with TLR-4 KO have less intestinal permeability to FITC-dextran than do TLR-4 WT mice after burn injury as a result of alterations in the tight junction protein occludin. These findings suggest that the greater intestinal permeability and barrier breakdown after burn injury is a TLR-4-dependent process. Toll-like receptor 4 may provide a useful target for the prevention and treatment of systemic inflammatory response syndrome and multisystem organ failure after injury.

Pulmonary surfactant: an immunological perspective

Pulmonary surfactant has two crucial roles in respiratory function; first, as a biophysical entity it reduces surface tension at the air water interface, facilitating gas exchange and alveolar stability during breathing, and, second, as an innate component of the lung's immune system it helps maintain sterility and balance immune reactions in the distal airways. Pulmonary surfactant consists of 90% lipids and 10% protein. There are four surfactant proteins named SP-A, SP-B, SP-C, and SP-D; their distinct interactions with surfactant phospholipids are necessary for the ultra-structural organization, stability, metabolism, and lowering of surface tension. In addition, SP-A and SP-D bind pathogens, inflict damage to microbial membranes, and regulate microbial phagocytosis and activation or deactivation of inflammatory responses by alveolar macrophages. SP-A and SP-D, also known as pulmonary collectins, mediate microbial phagocytosis via SP-A and SP-D receptors and the coordinated induction of other innate receptors. Several receptors (SP-R210, CD91/calreticulin, SIRPalpha, and toll-like receptors) mediate the immunological functions of SP-A and SP-D. However, accumulating evidence indicate that SP-B and SP-C and one or more lipid constituents of surfactant share similar immuno-regulatory properties as SP-A and SP-D. The present review discusses current knowledge on the interaction of surfactant with lung innate host defense.

Lung contusion: inflammatory mechanisms and interaction with other injuries

This article reviews current animal models and laboratory studies investigating the pathophysiology of lung contusion (LC), a common and severe condition in patients with blunt thoracic trauma. Emphasis is on studies elucidating cells, mediators, receptors, and processes important in the innate pulmonary inflammatory response that contribute to LC injury. Surfactant dysfunction in the pathogenesis of LC is also discussed, as is the potential role of epithelial cell or neutrophil apoptosis. Studies examining combination injuries where LC is exacerbated by secondary insults such as gastric aspiration in trauma patients are also noted. The need for continuing mechanism-based research to further clarify the pathophysiology of LC injury, and to define and test potential therapeutic interventions targeting specific aspects of inflammation or surfactant dysfunction to improve clinical outcomes in patients with LC, is also emphasized.

Pulmonary contusion primes systemic innate immunity responses

INTRODUCTION

Traumatic injury may result in an exaggerated response to subsequent immune stimuli such as nosocomial infection. This "second hit" phenomenon and molecular mechanism(s) of immune priming by traumatic lung injury, specifically, pulmonary contusion, remain unknown. We used an animal model of pulmonary contusion to determine whether the injury resulted in priming of the innate immune response and to test the hypothesis that resuscitation fluids could attenuate the primed response to a second hit.

METHODS

Male, 8 to 9 weeks, C57/BL6 mice with a pulmonary contusion were challenged by a second hit of intratracheal administration of the Toll-like receptor 4 agonist, lipopolysaccharide (LPS, 50 microg) 24 hours after injury (injury + LPS). Other experimental groups were injury + vehicle or LPS alone. A separate group was injured and resuscitated by 4 cc/kg of hypertonic saline (HTS) or Lactated Ringer's (LR) resuscitation before LPS challenge. Mice were killed 4 hours after LPS challenge and blood, bronchoalveolar lavage, and tissue were isolated and analyzed. Data were analyzed using one-way analysis of variance with Bonferroni multiple comparison posttest for significant differences (*p < or = 0.05).

RESULTS

Injury + LPS showed immune priming observed by lung injury histology and increased bronchoalveolar lavage neutrophilia, lung myeloperoxidase and serum IL-6, CXCL1, and MIP-2 levels when compared with injury + vehicle or LPS alone. After injury, resuscitation with HTS, but not Lactated Ringer's was more effective in attenuating the primed response to a second hit.

CONCLUSION

Pulmonary contusion primes innate immunity for an exaggerated response to a second hit with the Toll-like receptor 4 agonist, LPS. We observed synergistic increases in inflammatory mediator expression in the blood and a more severe lung injury in injured animals challenged with LPS. This priming effect was reduced when HTS was used to resuscitate the animal after lung contusion.