Daoxin Wang

Endocan levels in peripheral blood predict outcomes of acute respiratory distress syndrome.

Purpose. To investigate the prognostic significance of endocan, compared with procalcitonin (PCT), C-reactive protein (CRP),white blood cells (WBC), neutrophils (N), and clinical severity scores in patients with ARDS. Methods. A total of 42 patients with ARDS were initially enrolled, and there were 20 nonsurvivors and 22 survivors based on hospital mortality. Plasma levels of biomarkers were measured and the acute physiology and chronic health evaluation II (APACHE II) was calculated on day 1 after the patient met the defining criteria of ARDS. Results. Endocan levels significantly correlated with the APACHE II score in the ARDS group (r = 0.676, P = 0.000, n = 42). Of 42 individuals with ARDS, 20 were dead, and endocan was significantly higher in nonsurvivors than in survivors (median (IQR) 5.01 (2.98–8.44) versus 3.01 (2.36–4.36) ng/mL, P = 0.017). According to the results of the ROC-curve analysis and COX proportional hazards models, endocan can predict mortality of ARDS independently with a hazard ratio of 1.374 (95% CI, 1.150–1.641) and an area of receiver operator characteristic curve (AUROC) of 0.715 (P = 0.017). Moreover, endocan can predict the multiple-organ dysfunction of ARDS. Conclusion. Endocan is a promising biomarker to predict the disease severity and mortality in patients with ARDS.

Rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist, attenuates airway inflammation by inhibiting the proliferation of effector T cells in a murine model of neutrophilic asthma

An imbalanced Th17-mediated immune response contributes substantially to neutrophilic asthma. Studies have also demonstrated that peroxisome proliferator-activated receptor-γ (PPARγ) plays a critical role in inflammatory disease. However, the effect of PPARγ on airway inflammation in neutrophilic asthma remains unclear. In the current study, we evaluated the potential therapeutic role of rosiglitazone (RSG) in a new mouse model of asthma characterised by increased neutrophils rather than eosinophils. A co-culture system of DCs with CD4+ naïve T cells was established to evaluate the effects of RSG on T cell differentiation. After challenge with OVA, mice developed the typical pathophysiological features of asthma, including an increased number of neutrophils in the BALF and the up-regulation of IL-17. The numbers of Th17 cells and Th2 cells were also greatly elevated in the lungs. The administration of rosiglitazone reduced the pathophysiological features of asthma and decreased the up-regulated inflammatory mediators and cytokines. Furthermore, the cell viability in the co-culture system was markedly reduced by RSG. T-bet, Gata-3 and RORγt mRNA were down-regulated by RSG. These findings suggest that PPARγ is critical for airway inflammation during neutrophilic asthma, possibly due to its effect on Th cell proliferation and differentiation. These findings suggest that the therapeutic effect of rosiglitazone in neutrophilic asthma is partially due to the role of the PPARγ pathway in regulating T cell proliferation and differentiation.

Omentin protects against LPS-induced ARDS through suppressing pulmonary inflammation and promoting endothelial barrier via an Akt/eNOS-dependent mechanism

Acute respiratory distress syndrome (ARDS) is characterized by increased pulmonary inflammation and endothelial barrier permeability. Omentin has been shown to benefit obesity-related systemic vascular diseases; however, its effects on ARDS are unknown. In the present study, the level of circulating omentin in patients with ARDS was assessed to appraise its clinical significance in ARDS. Mice were subjected to systemic administration of adenoviral vector expressing omentin (Ad-omentin) and one-shot treatment of recombinant human omentin (rh-omentin) to examine omentin’s effects on lipopolysaccharide (LPS)-induced ARDS. Pulmonary endothelial cells (ECs) were treated with rh-omentin to further investigate its underlying mechanism. We found that a decreased level of circulating omentin negatively correlated with white blood cells and procalcitonin in patients with ARDS. Ad-omentin protected against LPS-induced ARDS by alleviating the pulmonary inflammatory response and endothelial barrier injury in mice, accompanied by Akt/eNOS pathway activation. Treatment of pulmonary ECs with rh-omentin attenuated inflammatory response and restored adherens junctions (AJs), and cytoskeleton organization promoted endothelial barrier after LPS insult. Moreover, the omentin-mediated enhancement of EC survival and differentiation was blocked by the Akt/eNOS pathway inactivation. Therapeutic rh-omentin treatment also effectively protected against LPS-induced ARDS via the Akt/eNOS pathway. Collectively, these data indicated that omentin protects against LPS-induced ARDS by suppressing inflammation and promoting the pulmonary endothelial barrier, at least partially, through an Akt/eNOS-dependent mechanism. Therapeutic strategies aiming to restore omentin levels may be valuable for the prevention or treatment of ARDS.

The Effect of Endogenous Angiotensin II on Alveolar Fluid Clearance in Rats with Acute Lung Injury

BACKGROUND In acute lung injury (ALI), angiotensin II (Ang II) plays a vital role in the stimulation of pulmonary permeability edema formation through the angiotensin type 1 (AT1) receptor. The effect of Ang II on alveolar fluid clearance (AFC) in ALI remains unknown. METHODS Sprague Dawley rats were anesthetized and intratracheally injected with 1 mg⁄kg lipopolysaccharide (LPS), while control rats received saline. The AT1 receptor antagonist ZD7155 was injected intraperitoneally (10 mg⁄kg) 30 min before LPS administration. The lungs were isolated for AFC measurement, and alpha-epithelial sodium channel (ENaC) messenger RNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot. RESULTS LPS-induced ALI caused an increase in Ang II levels in plasma and lung tissue but a decrease in AFC. The time course of Ang II levels paralleled that of AFC. Pretreatment with ZD7155 prevented ALI-induced reduction of AFC. ZD7155 also reversed the ALI-induced reduction of beta-ENaC and gamma-ENaC levels, and further decreased alpha-ENaC levels. CONCLUSIONS These findings suggest that endogenous Ang II inhibits AFC and dysregulates ENaC expression via AT1 receptors, which contribute to alveolar filling and pulmonary edema in LPS-induced ALI.

Vaspin protects against LPS‑induced ARDS by inhibiting inflammation, apoptosis and reactive oxygen species generation in pulmonary endothelial cells via the Akt/GSK‑3β pathway

Acute respiratory distress syndrome (ARDS) is characterized by uncontrolled extravasation of protein-rich fluids, which is caused by disruption and dysfunction of the barrier of pulmonary endothelial cells (ECs). Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a novel adipokine with pleiotropic properties, which has been reported to exert beneficial effects against obesity-associated systemic vascular diseases; however, its effects on ARDS remain unknown. In the present study, mice were subjected to systemic administration of adenoviral vector expressing vaspin (Ad-vaspin) to examine its effects on lipopolysaccharide (LPS)-induced ARDS in vivo. Histological analysis was then conducted, and cytokine [tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10] levels, and intercellular cell adhesion molecule-1 (ICAM-1) and adherens junctions (AJs) expression were detected. In addition, human pulmonary microvascular ECs (HPMECs) were treated with recombinant human (rh)-vaspin to further investigate its molecular basis and underlying mechanism. The mRNA expression levels of inflammatory cytokines (TNF-α and IL-6) and endothelial-specific adhesion markers [vascular cell adhesion molecule-1 and E-selectin], activation of nuclear factor-κB, and cell viability and apoptosis were then examined. Furthermore, the expression of AJs and organization of the cytoskeleton, as well as expression and activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and generation of reactive oxygen species (ROS) were determined. The results indicated that Ad-vaspin protected against LPS-induced ARDS by alleviating the pulmonary inflammatory response and pulmonary EC barrier dysfunction in mice, which was accompanied by activation of the protein kinase B (Akt)/glycogen synthase kinase (GSK)-3β pathway. In addition, pretreatment of HPMECs with rh-vaspin attenuated inflammation, apoptosis and ROS generation without alterations in AJs and cytoskeletal organization following LPS insult, which was accompanied by activation of the Akt/GSK3β pathway. In conclusion, the present study demonstrated that vaspin protects against LPS-induced ARDS by reversing EC barrier dysfunction via the suppression of inflammation, apoptosis and ROS production in pulmonary ECs, at least partially via activation of the Akt/GSK3β pathway. These findings provide evidence of a causal link between vaspin and EC dysfunction in ARDS, and suggest a potential therapeutic intervention for patients with ARDS.

Insulin upregulates the expression of epithelial sodium channel in vitro and in a mouse model of acute lung injury: Role of mTORC2/SGK1 pathway

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by proteinaceous pulmonary edema and severe arterial hypoxemia with a mortality of approximately 40%. Stimulation of epithelial sodium channel (ENaC) promotes Na(+) transport, a rate-limiting step for pulmonary edema reabsorption. Insulin is known to participate in the ion transport; however, its role in pulmonary edema clearance and the regulatory mechanism involved have not been fully elucidated. In the current study, in a lipopolysaccharide-based mouse model of ALI, we found that insulin alleviated pulmonary edema by promoting ENaC-mediated alveolar fluid clearance through serum and glucocorticoid induced kinase-1 (SGK1). In alveolar epithelial cells, insulin increased the expression of α-, β-, and γ-ENaC, which was blocked by the mammalian target of rapamycin complex 2 (mTORC2) inhibitor or knockdown of Rictor (a necessary component of mTORC2), and SGK1 inhibitor, respectively. In addition, an immunoprecipitation study demonstrated that SGK1(Ser422) phosphorylation, the key step for complete SGK1 activation by insulin, was conducted through PI3K/mTORC2 pathway. Finally, we testified the role of mTORC2 in vivo by demonstrating that PP242 prevented insulin-stimulated SGK1 activation and ENaC increase during ALI. The data revealed that during ALI, insulin stimulates alveolar fluid clearance by upregulating the expression of α-, β-, and γ-ENaC at the cell surface, which was, at least, partially through activating mTROC2/SGK1 signaling pathway.

Netrin-1 Promotes Epithelial Sodium Channel-Mediated Alveolar Fluid Clearance via Activation of the Adenosine 2B Receptor in Lipopolysaccharide-Induced Acute Lung Injury

Background: The epithelial sodium channel (ENaC) is the driving force for pulmonary edema absorption in acute lung injury (ALI). Netrin-1 is a newly found anti-inflammatory factor that works by activating the adenosine 2B receptor (A2BAR). Meanwhile, activated A2BAR has the potential to enhance ENaC-dependent alveolar fluid clearance (AFC). However, whether netrin-1 can increase ENaC-mediated AFC by activating A2BAR remains unclear. Objectives: To investigate the effect of netrin-1 on AFC in ALI and clarify the pathway via which netrin-1 regulates the expression of ENaC in vivo and in vitro. Methods: An ALI model was established by intratracheal instillation of lipopolysaccharide (LPS; 5 mg/kg) in C57BL/J mice, followed by netrin-1 with or without pretreatment with PSB1115, via the caudal vein. Twenty-four hours later, the lungs were isolated for determination of the bronchoalveolar lavage fluid, the lung wet/dry weight (W/D) ratio, AFC, the expressions of α-, β-, and γ-ENaC, and cyclic adenosine monophosphate (cAMP) levels. LPS-stimulated MLE-12 cells were incubated with netrin-1 with or without preincubation with PSB1115. Twenty-four hours later, the expressions of α-, β-, and γ-ENaC were detected. Results: In vivo, netrin-1 expression was significantly decreased during ALI. Substituted netrin-1 significantly dampened the lung injury, decreased the W/D ratio, and enhanced AFC, the expressions of α-, β-, and γ-ENaC, and cAMP levels in ALI, which were abolished by specific A2BAR inhibitor PSB1115. In vitro, netrin-1 increased the expressions of α-, β-, and γ-ENaC, which were prevented by PSB1115. Conclusion: These results indicate that netrin-1 dampens pulmonary inflammation and increases ENaC-mediated AFC to alleviate pulmonary edema in LPS-induced ALI by enhancing cAMP levels through the activation of A2BAR.

Association of Respiratory Syncytial Virus Toll-Like Receptor 3-Mediated Immune Response with COPD Exacerbation Frequency

The objective of the study is to explore the role of respiratory syncytial virus Toll-like receptor 3 (TLR3)-mediated immune response in the pathogenesis of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). A total of 20 AECOPD patients and 10 normal volunteers were studied. TLR3 was detected by RT-PCR, and respiratory syncytial virus (RSV) was detected by nested RT-PCR. Then, A549 cells were infected by RSV at different time points and at different viral titers. TLR3 mRNA was detected by RT-PCR, the protein of TLR3 and interferon regulatory factor 3 (IRF3) were detected by western blot, and IRF3 protein localization was detected by immunofluorescence. Interferon-β (IFN-β) and interleukin-6 (IL-6) were detected by ELISA. A total of 4 (20%) of the 20 AECOPD patients sampled were infected with RSV. The forced expiratory volume in 1 second (FEV1) percentage was lower in the AECOPD patients infected with RSV compared to those not infected (P = 0.03). The expression of IL-6 in the two groups was diametrically opposite (P = 0.04). The AECOPD group (n = 20) showed an increase in TLR3 mRNA compared with that of the control group (n = 10) (P = 0.02). The RSV-infected AECOPD group (n = 4) showed an obvious increase in TLR3 mRNA compared with that of the control group (P = 0.03). There was a significant correlation between severity of reduction in lung function at exacerbation and the increasing expression of TLR3 in AECOPD patients. The TLR3 signaling pathway was activated in lung epithelial cells. TLR3 mRNA/protein levels were increased in A549 infected with RSV compared with those of the control group. IRF3 protein also increased along with the occurrence of nuclear transfer in A549 infected with RSV. IFN-β and IL-6 were also increased in the RSV-infected A549 cells compared with those of the control (P = 0.00 and 0.00, respectively). Increased TLR3 expression in AECOPD patients is associated with declining lung function. TLR3 may be a risk factor for RSV-infected AECOPD patients.

Regulation of epithelial sodium channel expression by oestradiol and progestogen in alveolar epithelial cells

Oestrogen (E) and progestogen (P) exert regulatory effects on the epithelial Na(+) channel (ENaC) in the kidneys and the colon. However, the effects of E and P on the ENaC and on alveolar fluid clearance (AFC) remain unclear, and the mechanisms of action of these hormones are unknown. In this study, we showed that E and/or P administration increased AFC by more than 25% and increased the expression of the α and γ subunits of ENaC by approximately 35% in rats subjected to oleic acid-induced acute lung injury (ALI). A similar effect was observed in the dexamethasone-treated group. Furthermore, E and/or P treatment inhibited 11β-hydroxysteroid dehydrogenase (HSD) type 2 (11β-HSD2) activity, increased corticosterone expression and decreased the serum adrenocorticotrophic hormone (ACTH) levels. These effects were similar to those observed following treatment with carbenoxolone (CBX), a nonspecific HSD inhibitor. Further investigation showed that CBX further significantly increased AFC and α-ENaC expression after treatment with a low dose of E and/or P. In vitro, E or P alone inhibited 11β-HSD2 activity in a dose-dependent manner and increased α-ENaC expression by at least 50%, and E combined with P increased α-ENaC expression by more than 80%. Thus, E and P may augment the expression of α-ENaC, enhance AFC, attenuate pulmonary oedema by inhibiting 11β-HSD2 activity, and increase the active glucocorticoid levels in vivo and in vitro.

p300 promotes differentiation of Th17 cells via positive regulation of the nuclear transcription factor RORγt in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) has been the major cause of acute respiratory failure in critical patients and one of the leading causes of death worldwide for several decades. Th17 cells are involved in the occurrence and progression of ARDS. Furthermore, histone acetyltransferase (HAT) p300 is a transcriptional coactivator, and its activity is closely related to cancer and inflammatory diseases. p300 and histone deacetylase 1 (HDAC1) interact with and stabilize the nuclear transcription factor retinoic acid-related orphan receptor gamma t (RORγt) and participate in the regulation of RORγt-mediated IL-17 transcription in T helper 17 (Th17) cell differentiation by acetylation and deacetylation. However, the effect of p300 on RORγt and Th17 cells in ARDS is not well reported. Therefore, we aimed to investigate the clinical features of p300 and its effect on RORγt and Th17 cells in patients with ARDS as well as in lipopolysaccharide-induced acute lung injury (ALI) mouse models. Overexpression of p300 and RORγt mRNA was found in the peripheral blood mononuclear cells from patients with ARDS, especially among non-survivors, compared to that in healthy individuals (P < 0.05). Moreover, the decline of FOXP3 mRNA level correlated with survival and increased RORγt mRNA levels corelated with infection (P < 0.05). Immunohistochemical analysis revealed high p300 and RORγt expression in ALI mouse lung tissues. Inhibitor-mediated knockdown of p300 reduced lung tissue inflammation and lung injury score (P < 0.05). Western blotting and ELISA revealed that p300 inhibitor caused a decrease in the mRNA and protein levels of RORγt as well as interleukin 17 (IL-17) production in ALI mouse lung tissues (P < 0.05). Thus, our findings suggest that p300 may play a key role in ARDS by positively regulating RORγt transcription and is a potential new immunotherapy target for ARDS.