Zenglin Liao

Resolvin D1 attenuates inflammation in lipopolysaccharide-induced acute lung injury through a process involving the PPARγ/NF-κB pathway

BackgroundDocosahexaenoic acid (DHA) and DHA-derived lipid mediators have recently been shown to possess anti-inflammatory and pro-resolving properties. In fact, DHA can down-regulate lipolysaccharide (LPS)-induced activation of NF-κB via a PPARγ-dependent pathway. We sought to investigate the effects of the novel DHA-derived mediator resolvin D1 (RvD1) on LPS-induced acute lung injury and to determine whether these effects occur via a PPARγ-dependent pathway.MethodsBALB/c mice aged 6–8 weeks were randomly divided into seven groups: two control groups receiving saline or RvD1 (600 ng) without LPS; a control group receiving LPS only; an experimental group receiving RvD1 (300 ng) or RvD1 (600 ng), followed by LPS; a group receiving the PPARγ antagonist GW9662; and a group receiving GW9662, then RvD1 (600 ng) and finally LPS. LPS (50 μM) and saline were administered intratracheally. RvD1 was injected intravenously 24 h and 30 min before LPS, while GW9662 was injected intravenously 30 min before RvD1. Mice were killed at 6, 12, and 24 h. Samples of bronchoalveolar lavage fluid (BALF) were analyzed for cell counts and cytokine analysis. Lung tissues were collected for histology, Western blotting and electrophoretic mobility shift assays (EMSAs).ResultsAt all three time points, groups receiving either dose of RvD1 followed by LPS had significantly lower total leukocyte counts and levels of TNF-α and IL-6 levels in BALF than did the group given only LPS. RvD1 markedly attenuated LPS-induced lung inflammation at 24 h, based on hematoxylin-eosin staining of histology sections. RvD1 activated PPARγ and suppressed IκBα degradation and NF-κB p65 nuclear translocation, based on Western blots and EMSAs. The PPARγ inhibitor GW9662 partially reversed RvD1-induced suppression of IκBα degradation and p65 nuclear translocation.ConclusionsThese results suggest that RvD1 may attenuate lung inflammation of LPS-induced acute lung injury by suppressing NF-κB activation through a mechanism partly dependent on PPARγ activation.

Quercetin attenuates airway inflammation and mucus production induced by cigarette smoke in rats

Mucus hypersecretion is a feature of many chronic airway diseases induced by cigarette smoke (CS), and evidence suggests that the antioxidant and anti-inflammatory flavonoid quercetin may protect against CS-induced respiratory pathology. In this study, the ability of quercetin to protect against CS-induced mucin expression was examined in vivo and in vitro. Quercetin or 0.2% Tween aqueous solution was administered intraperitoneally to rats,which were then exposed to CS for 28 days. Cell counts and pro-inflammatory cytokine levels were measured in bronchoalveolar lavage fluid (BALF). Lung tissue was examined for total glutathione (GSH) and total antioxidant capacity (T-AOC), histopathological lesions, goblet cell hyperplasia, epidermal growth factor receptor (EGFR) phosphorylation and NF-κB pathway activation. To complement these in vitro studies, human airway epithelial NCI-H292 cells were pretreated with quercetin and then exposed to cigarette smoke extract (CSE). Cell lysates were examined for Muc5ac expression, EGFR phosphorylation and NF-κB pathway activation. In vivo, quercetin pretreatment suppressed CS-induced goblet cell hyperplasia, inflammation, oxidative stress, EGFR phosphorylation and NF-κB pathway activation in rat lung. In vitro, quercetin pretreatment attenuated the CSE-induced Muc5ac expression, NF-κB activation and EGFR phosphorylation. Our results suggest that quercetin attenuates CS-induced mucin protein synthesis in rat lung, possibly by inhibiting oxidative stress and inflammation via a mechanism involving NF-κB pathway activation and EGFR phosphorylation. These findings suggest that quercetin has a potential for treating chronic airway diseases.

Enhanced expression of human β-defensin 2 in peripheral lungs of patients with chronic obstructive pulmonary disease

Human β-defensin 2 (hBD-2) has antimicrobial activity and may play a role in airway mucosal defense, but studies have not yet examined its expression in lung tissue of patients with chronic obstructive pulmonary disease (COPD). Here we investigated hBD-2 levels in lung tissues of COPD patients and analyzed their correlations with IL-8, IL-1β, cigarette smoking and lung function in order to see whether the protein may be involved in pathogenesis of the disease. Peripheral lung tissue specimens were obtained from 51 patients who underwent lung resection for peripheral lung cancer: healthy non-smokers (n=8), healthy current smokers (n=7), non-smokers with COPD (n=11), and current smokers with COPD (n=25). RT-PCR and immunohistochemical staining were used to detect expression levels of hBD-2, IL-8 and IL-1β. Expression of hBD-2 mRNA was significantly higher in COPD patients than in healthy controls, and significantly higher in current smokers than in non-smokers (p<0.05). Among healthy controls, hBD-2 mRNA levels were similar between current smokers and non-smokers. Immunohistochemistry showed hBD-2 protein to be expressed mainly in epithelia of distal bronchioles and its expression pattern among our patient groups mirrored that of the mRNA. IL-8 mRNA levels were significantly higher in COPD patients than in healthy controls (p<0.05), while IL-1β mRNA levels did not differ significantly among the groups. Levels of hBD-2 mRNA positively correlated with levels of IL-8 mRNA (r=0.545, p=0.002), and negatively correlated with FEV1/FVC ratios and with predicted FEV1% values (r=-0.406, p=0.011). Our results indicate that hBD-2 expression is elevated in distal airways of COPD patients and that it may be involved in pathogenesis of the disease. Our data implicate cigarette smoking as a factor that may elevate hBD-2 levels in lung tissues of COPD patients.

WNT/β-catenin signaling regulates cigarette smoke-induced airway inflammation via the PPARδ/p38 pathway.

The mechanisms of WNT/β-catenin signaling involved in airway inflammation of chronic obstructive pulmonary disease (COPD) remain unknown, although recent observations have suggested an important contribution of the pathway in pulmonary parenchymal tissue repair and airway epithelium differentiation. We investigated the role of WNT/β-catenin signaling in cigarette smoke (CS)-related airway inflammation using patient lung tissues, human bronchial epithelial cells (16HBECs), and mouse models. Reduced activity of WNT/β-catenin signaling was observed in the airway epithelium of smokers with or without COPD. The mRNA expression of WNT transcription factor TCF4 negatively correlated with the pack year. The mRNA levels of WNT receptor FZD4 negatively correlated with the mRNA levels of IL-1β. CS exposure decreased the activity of WNT/β-catenin signaling in both 16HBECs and mice. In vitro studies demonstrated the upregulation of inflammatory cytokines TNF-α and IL-1β secretion induced by CS extract (CSE) could be attenuated by β-catenin activator SB216763 and be exacerbated by β-catenin small-interfering RNA (siRNA), respectively. Furthermore, the decrease in the expression of peroxisome proliferator-activated receptor (PPARδ) induced by CSE stimulation could be rescued by SB216763. SB216763 also attenuated the upregulation of phosphorylated p38 mitogen-activated protein kinase (MAPK) stimulated by CSE. Both PPARδ agonist and p38 MAPK inhibitor could suppress the TNF-α and IL-1β release induced by CSE treatment. In addition, PPARδ activation could abolish β-catenin siRNA-mediated aggravation of phosphorylated p38 MAPK in response to CSE. Finally, SB216763 treatment significantly ameliorated peribronchial inflammatory cell infiltration, leukocyte influx, and the release of TNF-α and IL-1β in the bronchoalveolar lavage fluid of CS-exposed mice. Taken together, our findings indicate that the reduced activity of WNT/β-catenin signaling induced by CS may promote inflammatory cytokine production in airway epithelium and have an essential role in airway inflammation in COPD by PPARδ/p38 MAPK pathway.

Increased expression of heat shock protein 70 in chronic obstructive pulmonary disease.

BACKGROUND Heat shock protein 70 (HSP70) plays a critical role in the process of inflammation and innate immunity response under environmental stress. OBJECTIVES This study was to investigate HSP70 expression in the peripheral lung tissues of chronic obstructive pulmonary disease (COPD) patients and in human bronchial epithelial cells (16-HBE) exposed to cigarette smoke extract (CSE). METHODS Peripheral lung tissues were collected after lung cancer resection from 26 patients without COPD, 20 with mild COPD and 15 with advanced COPD, classified by lung function criteria. Among these cases, 37 were smokers and 24 non-smokers. Lung tissues were examined for histopathological changes and levels of HSP70 and IL-8. Cultured 16-HBE cells were stimulated with CSE in the absence or presence of HSP70 neutralizing antibody and the expressions of IL-8 and phospho-EGFR protein were determined. RESULTS Compared to patients without COPD, the levels of HSP70 and IL-8 were significantly increased in the lung tissues of COPD patients and positively correlated with the severity of the disease. The HSP70 expression was significantly higher in current smokers than that in non-smokers. Moreover, CSE-induced HSP70 significantly enhanced IL-8 production and EGFR phosphorylation in 16-HBE cells. The increases in IL-8 and phospho-EGFR were blocked by anti-HSP70 antibody. CONCLUSIONS Our study clarified that increased expression of HSP70 is closely related to COPD disease severity and smoking status. Extracellular HSP70 regulated chemokine productions and EGFR phosphorylation and plays an important role in the CSE-induced inflammatory and innate immunity responses in bronchial epithelia cells.

Losartan attenuates chronic cigarette smoke exposure-induced pulmonary arterial hypertension in rats: Possible involvement of angiotensin-converting enzyme-2

Abstract Chronic cigarette smoking induces pulmonary arterial hypertension (PAH) by largely unknown mechanisms. Renin–angiotensin system (RAS) is known to function in the development of PAH. Losartan, a specific angiotensin II receptor antagonist, is a well-known antihypertensive drug with a potential role in regulating angiotensin-converting enzyme-2 (ACE2), a recently found regulator of RAS. To determine the effect of losartan on smoke-induced PAH and its possible mechanism, rats were daily exposed to cigarette smoke for 6months in the absence and in the presence of losartan. Elevated right ventricular systolic pressure (RVSP), thickened wall of pulmonary arteries with apparent medial hypertrophy along with increased angiotensin II (Ang II) and decreased ACE2 levels were observed in smoke-exposed-only rats. Losartan administration ameliorated pulmonary vascular remodeling, inhibited the smoke-induced RVSP and Ang II elevation and partially reversed the ACE2 decrease in rat lungs. In cultured primary pulmonary artery smooth muscle cells (PASMCs) from 3- and 6-month smoke-exposed rats, ACE2 levels were significantly lower than in those from the control rats. Moreover, PASMCs from 6-month exposed rats proliferated more rapidly than those from 3-month exposed or control rats, and cells grew even more rapidly in the presence of DX600, an ACE2 inhibitor. Consistent with the in vivo study, in vitro losartan pretreatment also inhibited cigarette smoke extract (CSE)-induced cell proliferation and ACE2 reduction in rat PASMCs. The results suggest that losartan may be therapeutically useful in the chronic smoking-induced pulmonary vascular remodeling and PAH and ACE2 may be involved as part of its mechanism. Our study might provide insight into the development of new therapeutic interventions for PAH smokers.

p38 MAPK and MMP-9 cooperatively regulate mucus overproduction in mice exposed to acrolein fog☆

OBJECTIVE To evaluate the role of p38 mitogen-activated protein kinase (MAPK) on mice airway inflammation, mucus production and the possible cross-talk between p38 MAPK and matrix metalloproteinase-9 (MMP-9) in mucin protein synthesis. METHODS Mice were exposed to 4.0 ppm of acrolein for 21 days with daily intraperitoneal injection of SB203580, a specific inhibitor of p38 MAPK. In control mice, sterile saline was administered instead. On days 7 and 21, mice were sacrificed to examine airway inflammation and mucus production by BALF cell counts, cytokine ELISA, and H&E and AB-PAS staining. The mRNA and protein levels of Muc5ac, p38 MAPK and MMP-9 in the lung were determined by RT-PCR, immunohistochemistry and Western blotting analysis. MMP-9 activity was measured by gelatin zymography. RESULTS Both the numbers of inflammatory cells and mucus-secreting goblet cells were significantly increased in the airways of mice exposed to acrolein as compared to the control mice. Acrolein-increased phosphorylation of p38 MAPK was significantly reduced by SB203580. The airway inflammation and goblet cell hyperplasia after acrolein challenge were also attenuated by SB203580 administration. Moreover, SB203580 treatment decreased the acrolein-induced increase of Muc5ac and MMP-9 expression and MMP-9 activity in airway epithelium. CONCLUSIONS The results indicate an important role of p38 MAPK in acrolein-induced airway inflammation and mucus hypersecretion in mice. The cooperation of p38 and MMP-9 may contribute to the mucin overproduction after inflammatory challenge.

Diagnostic Performance of Bronchoalveolar Lavage Fluid CD4/CD8 Ratio for Sarcoidosis: A Meta-analysis.

Background The usefulness of bronchoalveolar lavage fluid (BALF) CD4/CD8 ratio for diagnosing sarcoidosis has been reported in many studies with variable results. Therefore, we performed a meta-analysis to estimate the overall diagnostic accuracy of BALF CD4/CD8 ratio based on the bulk of published evidence. Methods Studies published prior to June 2015 and indexed in PubMed, OVID, Web of Science, Scopus and other databases were evaluated for inclusion. Data on sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were pooled from included studies. Summary receiver operating characteristic (SROC) curves were used to summarize overall test performance. Deekss funnel plot was used to detect publication bias. Results Sixteen publications with 1885 subjects met our inclusion criteria and were included in this meta-analysis. Summary estimates of the diagnostic performance of the BALF CD4/CD8 ratio were as follows: sensitivity, 0.70 (95%CI 0.64–0.75); specificity, 0.83 (95%CI 0.78–0.86); PLR, 4.04 (95%CI 3.13–5.20); NLR, 0.36 (95%CI 0.30–0.44); and DOR, 11.17 (95%CI 7.31–17.07). The area under the SROC curve was 0.84 (95%CI 0.81–0.87). There was no evidence of publication bias. Conclusion Measuring the BALF CD4/CD8 ratio may assist in the diagnosis of sarcoidosis when interpreted in parallel with other diagnostic factors.

RAGE-ligands axis: A new ‘driving force’ for cigarette smoke-induced airway inflammation in COPD?

Receptor for advanced glycation end products (RAGE) was recently shown to contribute to cigarette smoke (CS)‐induced airway inflammation in chronic obstructive pulmonary disease (COPD). In this study, RAGE small interfering ribonucleic acid (RNA) transfection attenuated increased messenger RNA levels of common RAGE ligands HMGB1, S100A8, S100A9 and S100A12, but not S100B following exposure to CS extract. Our findings and those from recent studies suggest a positive feedback involving RAGE and its ligands as a new ‘driving force’ for CS‐induced airway inflammation in COPD.

Silencing of c-kit with small interference RNA attenuates inflammation in a murine model of allergic asthma.

Asthma is a chronic respiratory disease characterized by the inflammation of the airways due to infiltration and activation of several inflammatory cells that produce cytokines. c-kit, a proto-oncogene that encodes a tyrosine kinase receptor, has been found to be associated with allergic inflammation. The aim of the present study was to assess whether silencing of c-kit with small interference RNA (siRNA) would attenuate inflammation in allergic asthma. A mouse model of ovalbumin (OVA)-induced allergic asthma was treated with systemic administration of anti-c-kit siRNA to inhibit the expression of the c-kit gene. siRNAs were injected through the vena caudalis. We measured inflammatory response in both anti-c-kit siRNA-treated and control mice. Systemic administration of siRNA could effectively inhibit the expression of the c-kit gene and reduce the infiltration of inflammatory cells (eosinophils and lymphocytes) into the lung tissue and bronchoalveolar lavage fluid. In addition, we found that c-kit siRNA can decrease the production of the T-helper type 2 (Th2) cytokines, interleukin 4 (IL-4) and IL-5, but has no influence on IFN-γ generation. These results show that inhibition of c-kit expression with siRNA can reduce the inflammatory response in allergic asthma.