Endothelial cell-specific anticoagulation reduces inflammation in a mouse model of acute lung injury.

Tissue factor (TF)-dependent coagulation contributes to lung inflammation and the pathogenesis of acute lung injury (ALI). In this study, we explored the roles of targeted endothelial anticoagulation in ALI using two strains of transgenic mice expressing either a membrane-tethered human tissue factor pathway inhibitor (hTFPI) or hirudin fusion protein on CD31+ cells, including vascular endothelial cells (ECs). ALI was induced by intratracheal injection of LPS, and after 24 h the expression of TF and protease-activated receptors (PARs) on EC in lungs were assessed, alongside the extent of inflammation and injury. The expression of TF and PARs on the EC in lungs was upregulated after ALI. In the two strains of transgenic mice, expression of either of hTFPI or hirudin by EC was associated with significant reduction of inflammation, as assessed by the extent of leukocyte infiltration or the levels of proinflammatory cytokines, and promoted survival after LPS-induced ALI. The beneficial outcomes were associated with inhibition of the expression of chemokine CCL2 in lung tissues. The protection observed in the CD31-TFPI-transgenic strain was abolished by injection of an anti-hTFPI antibody, but not by prior engraftment of the transgenic strains with WT bone marrow, confirming that the changes observed were a specific transgenic expression of anticoagulants by EC. These results demonstrate that the inflammation in ALI is TF and thrombin dependent, and that expression of anticoagulants by EC significantly inhibits the development of ALI via repression of leukocyte infiltration, most likely via inhibition of chemokine gradients. These data enhance our understanding of the pathology of ALI and suggest a novel therapeutic strategy for treatment.

Aerosolized antibiotics for ventilator-associated pneumonia: a pairwise and Bayesian network meta-analysis.

BACKGROUND: Aerosolized antibiotics have been proposed as a novel and promising treatment option for the treatment of ventilator-associated pneumonia (VAP). However, the optimum aerosolized antibiotics for VAP remain uncertain. METHODS: We included studies from two systematic reviews and searched PubMed, EMBASE, and Cochrane databases for other studies. Eligible studies included randomized controlled trials and observational studies. Extracted data were analyzed by pairwise and network meta-analysis. RESULTS: Eight observational and eight randomized studies were identified for this analysis. By pairwise meta-analysis using intravenous antibiotics as the reference, patients treated with aerosolized antibiotics were associated with significantly higher rates of clinical recovery (risk ratio (RR) 1.21, 95% confidence interval (CI) 1.09-1.34; P = 0.001) and microbiological eradication (RR 1.42, 95% CI 1.22-1.650; P < 0.0001). There were no significant differences in the risks of mortality (RR 0.88, 95% CI 0.74-1.04; P = 0.127) or nephrotoxicity (RR 1.00, 95% CI 0.72-1.39; P = 0.995). Using network meta-analysis, clinical recovery benefits were seen only with aerosolized tobramycin and colistin (especially tobramycin), and microbiological eradication benefits were seen only with colistin. Aerosolized tobramycin was also associated with significantly lower mortality when compared with aerosolized amikacin and colistin and intravenous antibiotics. The assessment of rank probabilities indicated aerosolized tobramycin presented the greatest likelihood of having benefits for clinical recovery and mortality, and aerosolized colistin presented the best benefits for microbiological eradication. CONCLUSIONS: Aerosolized antibiotics appear to be a useful treatment for VAP with respect to clinical recovery and microbiological eradication, and do not increase mortality or nephrotoxicity risks. Our network meta-analysis in patients with VAP suggests that clinical recovery benefits are associated with aerosolized tobramycin and colistin (especially tobramycin), microbiological eradication with aerosolized colistin, and survival with aerosolized tobramycin, mostly based on observational studies. Due to the low levels of evidence, definitive recommendations cannot be made before additional, large randomized studies are carried out.

Bcl-2 inhibitors reduce steroid-insensitive airway inflammation.

BACKGROUND: Asthmatic inflammation is dominated by accumulation of either eosinophils, neutrophils, or both in the airways. Disposal of these inflammatory cells is the key to disease control. Eosinophilic airway inflammation is responsive to corticosteroid treatment, whereas neutrophilic inflammation is resistant and increases the burden of global health care. Corticosteroid-resistant neutrophilic asthma remains mechanistically poorly understood and requires novel effective therapeutic strategies. OBJECTIVE: We sought to explore the underlying mechanisms of airway inflammation persistence, as well as corticosteroid resistance, and to investigate a new strategy of effective treatment against corticosteroid-insensitive neutrophilic asthma. METHODS: Mouse models of either eosinophil-dominated or neutrophil-dominated airway inflammation were used in this study to test corticosteroid sensitivity in vivo and in vitro. We also used vav-Bcl-2 transgenic mice to confirm the importance of granulocytes apoptosis in the clearance of airway inflammation. Finally, the Bcl-2 inhibitors ABT-737 or ABT-199 were tested for their therapeutic effects against eosinophilic or neutrophilic airway inflammation and airway hyperresponsiveness. RESULTS: Overexpression of Bcl-2 protein was found to be responsible for persistence of granulocytes in bronchoalveolar lavage fluid after allergic challenge. This was important because allergen-induced airway inflammation aggravated and persisted in vav-Bcl-2 transgenic mice, in which nucleated hematopoietic cells were overexpressed with Bcl-2 and resistant to apoptosis. The Bcl-2 inhibitors ABT-737 or ABT-199 play efficient roles in alleviation of either eosinophilic or corticosteroid-resistant neutrophilic airway inflammation by inducing apoptosis of immune cells, such as eosinophils, neutrophils, TH2 cells, TH17 cells, and dendritic cells. Moreover, these inhibitors were found to be more efficient than steroids to induce granulocyte apoptosis ex vivo from patients with severe asthma. CONCLUSION: Apoptosis of inflammatory cells is essential for clearance of allergen-induced airway inflammation. The Bcl-2 inhibitors ABT-737 or ABT-199 might be promising drugs for the treatment of airway inflammation, especially for corticosteroid-insensitive neutrophilic airway inflammation.

Interaction of caveolin-1 with ATG12-ATG5 system suppresses autophagy in lung epithelial cells.

Autophagy plays a pivotal role in cellular homeostasis and adaptation to adverse environments, although the regulation of this process remains incompletely understood. We have recently observed that caveolin-1 (Cav-1), a major constituent of lipid rafts on plasma membrane, can regulate autophagy in cigarette smoking-induced injury of lung epithelium, although the underlying molecular mechanisms remain incompletely understood. In the present study we found that Cav-1 interacted with and regulated the expression of ATG12-ATG5, an ubiquitin-like conjugation system crucial for autophagosome formation, in lung epithelial Beas-2B cells. Deletion of Cav-1 increased basal and starvation-induced levels of ATG12-ATG5 and autophagy. Biochemical analyses revealed that Cav-1 interacted with ATG5, ATG12, and their active complex ATG12-ATG5. Overexpression of ATG5 or ATG12 increased their interactions with Cav-1, the formation of ATG12-ATG5 conjugate, and the subsequent basal levels of autophagy but resulted in decreased interactions between Cav-1 and another molecule. Knockdown of ATG12 enhanced the ATG5-Cav-1 interaction. Mutation of the Cav-1 binding motif on ATG12 disrupted their interaction and further augmented autophagy. Cav-1 also regulated the expression of ATG16L, another autophagy protein associating with the ATG12-ATG5 conjugate during autophagosome formation. Altogether these studies clearly demonstrate that Cav-1 competitively interacts with the ATG12-ATG5 system to suppress the formation and function of the latter in lung epithelial cells, thereby providing new insights into the molecular mechanisms by which Cav-1 regulates autophagy and suggesting the important function of Cav-1 in certain lung diseases via regulation of autophagy homeostasis.

Author Correction: Eosinophil differentiation in the bone marrow is promoted by protein tyrosine phosphatase SHP2.

Since the publication of the article, the authors became aware that Figs. 1c, 5k and 6m contained errors in representative image and PAS score in control groups. The corrected Figs. 1c, 5k, and 6m are given below, and the figure legends are the same as original.

Suhuang antitussive capsule at lower doses attenuates airway hyperresponsiveness, inflammation, and remodeling in a murine model of chronic asthma.

Suhuang antitussive capsule (Suhuang), a traditional Chinese medication, is found effective in treating chronic cough and cough variant asthma (CVA). This study aimed to determine the possible effects and underlying mechanisms of Suhuang on chronic ovalbumin (OVA)-induced airway hyperresponsiveness (AHR), inflammation, and remodeling in mice. Mice were randomly assigned to six experimental groups: control, OVA model with or without Suhuang (low dose: 3.5 g/kg, middle dose: 7.0 g/kg, high dose: 14.0 g/kg), or dexamethasone (2.5 mg/kg). AHR, inflammatory cells, cytokines in bronchoalveolar lavage fluid (BALF), lung pathology, mucus production, and airway remodeling were examined. We found Suhuang treated at lower doses effectively inhibited OVA-induced AHR, airway inflammation, mucus production and collagen deposition around the airway. High dose of Suhuang reduced most of the inflammatory hallmarks while exerted inconsiderable effects on the number of macrophages in BALF and AHR. At all doses, Suhuang significantly reduced the levels of interlukin (IL) -13 and transforming growth factor (TGF)-ß1, but had little effects on IL-4, IL-5, IL-17A and interferon (IFN)-γ. Thus, Suhuang administration alleviates the pathological changes of chronic asthma likely through inhibition of IL-13 and TGF-ß1. Suhuang might be a promising therapy for patients with allergic asthma in the future.