Dao-Feng Ben

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.

Role of p38 mitogen-activated protein kinase in lung injury after burn trauma.

This study was undertaken to evaluate the effect of SB203580, a specific p38 mitogen-activated protein (MAP) kinase inhibitor, on burn-induced lung injury as well as the release of tumor necrosis factor (TNF)-&agr; and interleukin (IL)-1&bgr; in rats to characterize the role of p38 MAP kinase in lung injury after burn trauma. Sprague-Dawley rats were divided into three groups: 1) sham group, or rats who underwent sham burn; 2) control group, or rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; and 3) SB203580 group, or rats given burn injury and lactated Ringers solution with SB203580 inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis. TNF-&agr; and IL-1&bgr; protein in bronchoalveolar lavage fluid and serum were measured by enzyme-linked immunosorbent assay and p38 MAP kinase was activity determined in lung by Western blot analysis. These studies showed that significant activation of p38 MAP kinase at 24 h postburn compared with control. Burn trauma resulted in increased pulmonary capillary leakage permeability, elevated levels of TNF-&agr; and IL-1&bgr; in bronchoalveolar lavage fluid and serum, and worsened histologic condition. SB203580 inhibited the activation of p38 MAP kinase, reduced the levels of TNF-&agr; and IL-1&bgr;, and prevented burn-mediated lung injury. These data suggest that p38 MAP kinase activation is one important aspect of the signaling event that may mediate the release of TNF-&agr; and IL-1&bgr; and contributes to burn-induced lung injury.

Role of p38 mitogen-activated protein kinase in Kupffer cell secretion of the proinflammatory cytokines after burn trauma.

This study was designed to investigate the role of p38 mitogen-activated protein (MAP) kinase on Kupffer cells (KCs) secretion of proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta and hepatic injury following burn trauma. Sprague-Dawley rats were randomized into four groups: (1) sham burn rats given vehicle, (2) sham burn rats given the p38 MAP kinase inhibitor SB203580 (10mg/kg i.v., 15min and 12h after sham burn), (3) rats given a 30% total body surface area (TBSA) full-thickness burn and fluid resuscitation plus vehicle, and (4) burn rats given injury and fluid resuscitation plus SB203580. Rats from each group were killed at 24h post-burn to examine plasma aspartate transaminase (AST) and alanine transaminase (ALT) and KCs were isolated. The KCs secretion of TNF-alpha and IL-1beta and p38 MAP kinase activity (by Western blot analysis) were also examined. These studies showed by more significant activation of p38 MAP kinase in KCs harvested from burn rats than from shams. Burn trauma resulted in hepatic dysfunction and promoted KCs secretion of TNF-alpha and IL-1beta. SB203580 inhibited p38 MAP kinase activity, reduced KCs secretion of proinflammatory cytokines, and alleviated burn-mediated hepatic dysfunction. These data suggest p38 MAP kinase activation is one important aspect of the signaling event that may mediate the KCs secretion of proinflammatory cytokines TNF-alpha and IL-1beta following burn trauma.

Angiotensin II induces type I collagen gene expression in human dermal fibroblasts through an AP-1/TGF-β1-dependent pathway

Angiotensin II is critically involved in skin wound healing, but the underlying mechanism remains unclear. This study investigated the effect of angiotensin II on type I collagen gene activation in human dermal fibroblasts and the possible mechanism involved. Angiotensin II stimulated the mRNA and protein expression of type I collagen and TGF-beta1. Effects were abolished by the angiotensin AT1 receptor antagonist ZD7155 but not by the AT2 blocker PD123319. Blockade of TGF-beta1 markedly inhibited angiotensin II-induced type I collagen gene expression. Activator protein-1 (AP-1) decoy ODNs transfection suppressed angiotensin II-induced TGF-beta1 expression, and also, diminished type I collagen expression. These data indicated that angiotensin II induces collagen gene activation in human dermal fibroblasts through an AT1-mediated AP-1/TGF-beta1 signaling pathway.

Role of inhibition of p38 mitogen-activated protein kinase in liver dysfunction after hemorrhagic shock and resuscitation

BACKGROUND The liver is one of the organs most frequently affected by trauma and hemorrhagic shock; the exact role of p38 mitogen-activated protein kinase (MAPK) activation in response to hepatic hemorrhagic shock/resuscitation (HS/R) remains unclear. MATERIALS AND METHODS C57Bl/6 mice were divided into four groups: sham-operated group, SB-only group, control group, and SB + HS/R group. Hepatocellular injury (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]) and tumor necrosis factor (TNF-α) and interleukin (IL-1β) messenger ribonucleic acid (mRNA) expression in the liver were assessed 6 h after resuscitation, p38 MAPK activation in the liver was assessed at 30 min after resuscitation. RESULTS p38 MAPK activation was higher in the control group than other groups 30 min after resuscitation. p38 MAPK activation level in the SB + HS/R group did not change significantly compared with that of sham and SB-only groups, but was significantly lower than that in the control group. The TNF-α mRNA expression in the control group was significantly higher than that in the sham group. The TNF-α mRNA levels after HS/R in the SB + HS/R group were significantly lower than those in the control group and were roughly the same as those in the sham and SB-only groups. IL-1β mRNA expression showed similar changes in the four groups. Serum ALT and AST levels in the control group were significantly higher than those in the sham group. The increase in serum ALT and AST levels after HS/R in the SB + HS/R group was significantly less pronounced than that in the control group and markedly higher than that in the sham group. CONCLUSIONS p38 MAPK was phosphorylated during the HS/R process. Inhibiting the activation of p38 MAPK may attenuate HS/R injury to the liver.

Pathogenic alteration in severe burn wounds

The present study aims to define the trend of time related changes with local bacterial alteration of bacterial resistance in severe burns in our burn center during a 12-year period. Retrospective analysis of microbiological results on severely burned wounds between 1998 and 2009 was carried out. A study of 3615 microbial isolates was performed. Staphylococcus aureus was the most commonly isolated pathogen (38.2%) followed by A. baumannii (16.2%), Streptococcus viridans (11.4%), Pseudomonas aeruginosa (10.4%), coagulase-negative staphylococci (CNS, 9.2%). The species ratios of S. aureus and A. baumannii increased significantly from 1st to 8th week of hospitalization, while those of Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci decreased during the same period. Bacterial resistance rates were compared between the periods 1998-2003 and 2004-2009. Vancomycin remained as the most sensitive antibiotic in S. aureus including methicillin-resistant S. aureus (MRSA). It was very likely that the majority of infections caused by Streptococcus viridans, P. aeruginosa and coagulase-negative staphylococci occurred in the early stage of burn course and the majority of infections caused by A. baumannii occurred 4 weeks after admission. The use of different antibiotics was probably the major contributor to these trends.

Expression and regulation of vascular cell adhesion molecule-1 in human umbilical vein endothelial cells induced by sera from severely burned patients.

ObjectiveThe purpose of this study was to determine the expression and regulation of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs) induced by sera from severely burned patients. DesignControlled laboratory study. SettingsResearch laboratory in a university hospital. SubjectsHUVECs. InterventionsHUVECs were incubated with serum from eight healthy controls and eight patients with thermal injuries of >50% total body surface area. The experiment was repeated after pretreatment with pyrrolidine dithiocarbamate, an inhibitory effect on nuclear factor-&kgr;B activation, SB203580, a specific p38 mitogen-activated protein kinase inhibitor, and PD98059, a mitogen-activated protein/extracellular signal-regulated kinase inhibitor. Measurements and Main ResultsProtein and messenger RNA expression of VCAM-1 was measured by flow cytometry and reverse transcription–polymerase chain reaction respectively. Soluble VCAM-1 level in HUVECs culture supernatants was measured by enzyme-linked immunosorbent assay. Sera from severely burned patients showed a stimulatory effect on VCAM-1 messenger RNA levels and an increased VCAM-1 expression on the endothelial cell surfaces. The soluble form of VCAM-1 molecules was also elevated by the stimulation of burn sera. In vitro peripheral blood mononuclear leukocytes adherence to HUVECs incubated with burn sera was significantly increased compared with those incubated with control sera. Finally, these events were significantly inhibited by pretreatment with antioxidants pyrrolidine dithiocarbamate or SB203580, whereas PD98059 had no significant effect. ConclusionsThese findings suggest that sera from severely burned patients induced up-regulation of VCAM-1 expressions in HUVECs, and this process might be largely dependent on oxidant-mediated nuclear factor-&kgr;B activation and p38 mitogen-activated protein kinase pathways.

Burn injuries caused by ship fire: A 12-year study in Shanghai

UNLABELLED The 105 patients admitted to our Burn Institute from 1st January 1996 to 31st December 2007, with ship fire-related burns were studied retrospectively. The mean age was 30.2+/-12.6 years with a range of 1-58. One hundred and three patients (98.1%) were men and 2 (1.9%) women. The mean total burn surface area (TBSA) was 46.5%, mostly deep burns. The most common areas of burn were the head, neck and upper limb. Summer months July, August, June and September were times of highest incidence. Fifty-seven (54.3%) patients had inhalation injury, 42 received tracheotomy, and 38 received mechanical ventilation. The treatment was complex, difficult, long, and costly. The interval between burn and start of resuscitation ranged from 2.1 to 67 h with a mean of (5.9+/-4.4)h. Forty-two patients (40%) started intravenous fluid resuscitation 6h after burn. Twenty-four patients (23%) received insufficient fluid resuscitation developed hypotension and severe shock at admission. Ninety-two (87.6%) patients required operations including tracheotomy, debridement and grafting, per patient was 5.2. The mean length of hospital stay was 44.2 days. Pulmonary edema was the most common complication during the early post-burn period (within 7 days), and sepsis during the later period (>7 days). Nine patients died of MODS or sepsis, giving a mortality rate of 8.57%. CONCLUSION Caution and preventive measures are needed for persons in ships for fire-related burns.

Knockdown of Burton’s tyrosine kinase confers potent protection against sepsis-induced acute lung injury

Sepsis is a common and critical complication in surgical patients that often leads to multiple organ failure syndrome (MOFS), including acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Despite intensive supportive care and treatment modalities, the mortality of these patients remains high. In this study, we investigated the role of Burton’s tyrosine kinase (BTK), a member of the Btk/Tec family of cytoplasmic tyrosine kinases, in the pathogenesis of sepsis, and evaluated the protective effect of in vivo Btk RNA interference in a mouse model of cecal ligation and puncture (CLP)-induced sepsis. After intratracheal injection of Btk siRNA, the mice were then subjected to CLP to induce sepsis. The results demonstrated that this approach conferred potent protection against sepsis-induced ALI, as evidenced by a significant reduction in pathological scores, epithelial cell apoptosis, pulmonary edema, vascular permeability, and the expression of inflammatory cytokines and neutrophil infiltration in the lung tissues of septic mice. In addition, RNA interference of Btk significantly suppressed p-38 and iNOS signaling pathways in transduced alveolar macrophages in vitro. These results identify a novel role for BTK in lethal sepsis and provide a potential new therapeutic approach to sepsis and ALI.

Acute pulmonary embolism complicated by thrombolytic therapy.

A 38-year-old woman presented with acute onset of chest pain, shortness of breath, and hemoptysis. She reported that she had been receiving thrombolytic and anticoagulation therapy in the previous 3 weeks for the diagnosis of thrombotic formation of the left common femoral vein secondary to a traumatic injury to the hip and lower extremity in a car accident. Examination on admission showed normal blood pressure, electrocardiograms, and chest radiograph, but subnormal arterial oxygen tension. Contrast-enhanced computed tomographic arteriography with thoracic coronary remodeling revealed an embolus in the lower right pulmonary artery causing incomplete obstruction of the artery (Fig. 1, arrow). Doppler ultrasonography confirmed the previous diagnosis of thrombotic formation of left common femoral vein, but the size of the thrombus was only about two-fifths of the previous one detected 3 weeks earlier, which supported the presumption that the embolus of pulmonary embolism originated from deep venous thrombus fragments of the thrombolytic therapy. To prevent pulmonary embolism from occurring again, an inferior vena caval filter was placed. After continuous anticoagulation therapy with low molecular weight-heparin and warfarin, the pulmonary embolus of the patient disappeared completely, but the residual femoral vein thrombosis did not change further for the better significantly. The filter was retrieved 2 months later. No new thromboembolic event occurred during a 4-month follow-up period. Pulmonary embolism is an acute and potentially lethal condition, the diagnosis of which remains difficult. It usually originates from deep vein thrombosis of the lower extremities. Systemic thrombolytic treatment for acute deep vein thrombosis may not only improve shortand long-term clinical outcomes but also increase the risk of acute pulmonary embolism as indicated by this case. The optional and preferable solution to this complication is placement of an inferior vena caval filter early enough. Submitted for publication July 9, 2008. Accepted for publication July 22, 2008. Copyright