Phillygenin inhibits the inflammation and apoptosis of pulmonary epithelial cells by activating PPARγ signaling via downregulation of MMP8

Acute lung injury (ALI) is often responsible for the high morbidity of critically ill patients. The present study aimed to investigate whether phillygenin (PHI) can inhibit inflammation and apoptosis of pulmonary epithelial cells by activating peroxisome proliferator-activated receptor γ (PPARγ) signaling. The in vitro model of ALI was established using lipopolysaccharide (LPS) and PHI was used to treat the LPS-induced cells. Cell viability was assessed using the MTT assay and the concentration levels of the inflammatory factors were detected by ELISA. Western blotting and reverse transcription-quantitative PCR were conducted to measure the expression levels of the inflammation- and apoptosis-associated proteins. The MMP8-overexpression plasmid was transfected into LPS-induced cells, which were treated with PHI treatment and the expression levels of PPARγ were detected via western blotting. PHI treatment suppressed the induction of inflammation and apoptosis of LPS-induced BEAS-2B cells. Furthermore, the expression levels of MMP8 in BEAS-2B cells induced by LPS were decreased following PHI treatment. Following transfection of the MMP8 overexpression plasmid into the LPS-induced BEAS-2B cells and subsequent treatment of these cells with PHI, the expression levels of PPARγ were decreased. In conclusion, it was shown that PHI inhibited the inflammation and apoptosis of pulmonary epithelial cells by activating PPARγ signaling via downregulating MMP8. These data may provide valuable information for future studies exploring the therapeutic effects of PHI for ALI.

Exploring the Use of Medicinal Plants and Their Bioactive Derivatives as Alveolar NLRP3 Inflammasome Regulators during Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a successful intracellular pathogen that is responsible for the highest mortality rate among diseases caused by bacterial infections. During early interaction with the host innate cells, M. tuberculosis cell surface antigens interact with Toll like receptor 4 (TLR4) to activate the nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 3 (NLRP3) canonical, and non-canonical inflammasome pathways. NLRP3 inflammasome activation in the alveoli has been reported to contribute to the early inflammatory response that is needed for an effective anti-TB response through production of pro-inflammatory cytokines, including those of the Interleukin 1 (IL1) family. However, overstimulation of the alveolar NLRP3 inflammasomes can induce excessive inflammation that is pathological to the host. Several studies have explored the use of medicinal plants and/or their active derivatives to inhibit excessive stimulation of the inflammasomes and its associated factors, thus reducing immunopathological response in the host. This review describes the molecular mechanism of the NLRP3 inflammasome activation in the alveoli during M. tuberculosis infection. Furthermore, the mechanisms of inflammasome inhibition using medicinal plant and their derivatives will also be explored, thus offering a novel perspective on the alternative control strategies of M. tuberculosis-induced immunopathology.

Oral Pathogen Fusobacterium nucleatum Coaggregates With Pseudomonas aeruginosa to Modulate the Inflammatory Cytotoxicity of Pulmonary Epithelial Cells

Chronic obstructive pulmonary disease (COPD) is the third leading cause of mortality worldwide, and inflammatory damage induced by bacterial infections is an important contributor to the etiology of COPD. Fusobacterium nucleatum, a recognized periodontal pathogen, is considered as a biomarker of lung function deterioration of COPD patients coinfected with Pseudomonas aerugionsa, but the underlying mechanism is still unclear. This study established single- and dual-species infection models, bacterial simultaneous and sequential infection models, and found that F. nucleatum could coaggregate with P. aeruginosa to synergistically invade into pulmonary epithelial cells and transiently resist P. aeruginosa-induced cytotoxic damage to amplify IL-6 and TNF-α associated inflammation in pulmonary epithelial cells simultaneously infected with P. aeruginosa and F. nucleatum. Furthermore, F. nucleatum pretreatment or subsequential infection could maintain or even aggravate P. aeruginosa-induced inflammatory cytotoxicity of pulmonary epithelial cells. These results indicate that oral pathogen F. nucleatum coaggregates with P. aeruginosa to facilitate bacterial invasion and modulates the inflammatory cytotoxicity of pulmonary epithelial cells, which may contribute to lung function deterioration of COPD patients accompanied with P. aeruginosa and F. nucleatum coinfection.

Silencing of lncRNA MALAT1 Prevents Inflammatory Injury after Lung Transplant Ischemia-Reperfusion by Downregulation of IL-8 via p300

Ischemia-reperfusion injury is a common early complication after lung transplantation. It was reported that long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in ischemia-reperfusion injury and regulates inflammation. This study aimed to explore the role of MALAT1 in inflammatory injury following lung transplant ischemia-reperfusion (LTIR). A LTIR rat model was successfully established, with the expression of MALAT1 and interleukin-8 (IL-8) in lung tissues detected. Then, in vitro loss- and gain-of-function investigations were conducted to evaluate the effect of MALAT1 on pulmonary epithelial cell apoptosis and IL-8 expression. The relationship among MALAT1, p300, and IL-8 was tested. Moreover, a sh-MALAT1-mediated model of LTIR was established in vivo to examine inflammatory injury and chemotaxis infiltration. Both IL-8 and MALAT1 were highly expressed in LTIR. MALAT1 interacted with p300 to regulate the IL-8 expression by recruiting p300. Importantly, silencing of MALAT1 inhibited the chemotaxis of neutrophils by downregulating IL-8 expression via binding to p300. Besides, MALAT1 silencing alleviated the inflammatory injury after LTIR by downregulating IL-8 and inhibiting infiltration and activation of neutrophils. Collectively, these results demonstrated that silencing of MALAT1 ameliorated the inflammatory injury after LTIR by inhibiting chemotaxis of neutrophils through p300-mediated downregulation of IL-8, providing clinical insight for LTIR injury.

[Experimental study of miRNA200a regulating Wnt/β-catenin signaling pathway in silica-induced mouse lung epithelial cells]

Objective: To observe the effect of overexpression of miRNA200a (miR-200a) recombinant lentivirus on the expression of Wnt/β-catenin signaling pathway in mouse lung epithelial cell line MLE-12 induced by silica (SiO(2)) . Methods: The mice were divided into SiO(2) control group (SiO(2)) , virus control group (SiO(2)+Lv-NC) group and overexpressing miR-200a virus group (SiO(2)+Lv-miR-200a). The expression of β-catenin, MMP2, MMP9, TCF-4 and Cyclin D1 mRNA and protein were detected by realtime-PCR and western blot after incubating cells for 18 h stimulating at the final concentration of 200 μg/ml of SiO(2). Results: The expression of miR-200a in MLE-12 cells of SiO(2)+Lv-miR-200 a group was significantly higher than that in SiO(2) group and SiO(2)+Lv-NC group. The mRNA and protein expression of β-catenin, MMP2, MMP9, TCF-4 and Cyclin D1 in MLE-12 cells of SiO(2)+Lv-miR-200a group were significantly lower than those in SiO(2) group and SiO(2)+Lv-NC group (P<0.05) . Conclusion: Overexpression of miR-200a can inhibit the expression of related genes of Wnt/β-catenin signaling pathway in silica-induced mouse lung epithelial cells.

Uptake and efflux kinetics, and intracellular activity of voriconazole against Aspergillus fumigatus in human pulmonary epithelial cells: a new application for the prophylaxis and early treatment of invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis (IPA), most caused by Aspergillus fumigatus, is a serious life-threatening infection in immunocompromised patients. Voriconazole is used to prevent and treat IPA. However, little is known about the pharmacological characteristics of voriconazole in pulmonary epithelial cells, which are the target site for the prophylaxis and early treatment of IPA. The aim of the study was to evaluate the kinetics and activity of voriconazole against A. fumigatus in A549 cells. High-performance liquid chromatography/tandem mass spectrometry and time-kill method were used to study the cellular pharmacokinetic and pharmacodynamics of voriconazole. Voriconazole exerted a concentration-dependent toxic effect on A549 cells and could penetrate into cells, reaching plateau concentrations of 1.14 ± 0.64, 3.72 ± 1.38 and 6.36 ± 0.95 ng/mg protein after A549 cells were exposed to voriconazole at extracellular concentrations of 2, 8 and 16 mg/L for 2 h, respectively. The efflux of voriconazole was rapid, with a half-life of 10.2 min. Voriconazole can decrease the A. fumigatus conidia invade cells, and the number of viable A. fumigatus conidia in cells can be decreased 2.1- to 20.6-fold when A549 cells were cultured in medium containing voriconazole. After 24-h incubation, 75.6% and 80.5% of intracellular A. fumigatus were killed when extracellular voriconazole concentration was 8 and 16 mg/L, respectively. This study illustrated a new application for the prophylaxis and early treatment of IPA from the cellular pharmacokinetics and pharmacodynamics and emphasized the importance of monitoring concentrations of voriconazole in epithelial lining fluid in immunocompromised patients receiving voriconazole therapy.

Lung-derived exosome uptake into and epigenetic modulation of marrow progenitor/stem and differentiated cells

Background

Our group has previously demonstrated that murine whole bone marrow cells (WBM) that internalize lung-derived extracellular vesicles (LDEVs) in culture express pulmonary epithelial cell–specific genes for up to 12 weeks. In addition, the lungs of lethally irradiated mice transplanted with lung vesicle–modulated marrow have 5 times more WBM-derived type II pneumocytes compared to mice transplanted with unmanipulated WBM. These findings indicate that extracellular vesicle modification may be an important consideration in the development of marrow cell–based cellular therapies. Current studies were performed to determine the specific marrow cell types that LDEV stably modify.

Methods

Murine WBM-derived stem/progenitor cells (Lin-/Sca-1+) and differentiated erythroid cells (Ter119+), granulocytes (Gr-1+) and B cells (CD19+) were cultured with carboxyfluorescein N-succinimidyl ester (CFSE)-labelled LDEV. LDEV+ cells (CFSE+) and LDEV− cells (CFSE−) were separated by flow cytometry and visualized by fluorescence microscopy, analyzed by RT-PCR or placed into long-term secondary culture. In addition, murine Lin-/Sca-1+ cells were cultured with CFSE-labelled LDEV isolated from rats, and RT-PCR analysis was performed on LDEV+ and – cells using species-specific primers for surfactant (rat/mouse hybrid co-cultures).

Results

Stem/progenitor cells and all of the differentiated cell types studied internalized LDEV in culture, but heterogeneously. Expression of a panel of pulmonary epithelial cell genes was higher in LDEV+cells compared to LDEV − cells and elevated expression of these genes persisted in long-term culture. Rat/mouse hybrid co-cultures revealed only mouse-specific surfactant B and C expression in LDEV+ Lin-/Sca-1+cells after 4 weeks of culture, indicating stable de novo gene expression.

Conclusions

LDEV can be internalized by differentiated and more primitive cells residing in the bone marrow in culture and can induce stable de novo pulmonary epithelial cell gene expression in these cells for several weeks after internalization. The gene expression represents a transcriptional activation of the target marrow cells. These studies serve as the basis for determining marrow cell types that can be used for cell-based therapies for processes that injure the pulmonary epithelial surfaces.

Reduced GM1 ganglioside in CFTR-deficient human airway cells results in decreased β1-integrin signaling and delayed wound repair

Loss of cystic fibrosis transmembrane conductance regulator (CFTR) function reduces chloride secretion and increases sodium uptake, but it is not clear why CFTR mutation also results in progressive lung inflammation and infection. We previously demonstrated that CFTR-silenced airway cells migrate more slowly during wound repair than CFTR-expressing controls. In addition, CFTR-deficient cells and mouse models have been reported to have altered sphingolipid levels. Here, we investigated the hypothesis that reduced migration in CFTR-deficient airway epithelial cells results from altered sphingolipid composition. We used cell lines derived from a human airway epithelial cell line (Calu-3) stably transfected with CFTR short hairpin RNA (CFTR-silenced) or nontargeting short hairpin RNA (controls). Cell migration was measured by electric cell substrate impedance sensing (ECIS). Lipid analyses, addition of exogenous glycosphingolipids, and immunoblotting were performed. We found that levels of the glycosphingolipid, GM1 ganglioside, were ~60% lower in CFTR-silenced cells than in controls. CFTR-silenced cells exhibited reduced levels of activated β1-integrin, phosphorylated tyrosine 576 of focal adhesion kinase (pFAK), and phosphorylation of Crk-associated substrate (pCAS). Addition of GM1 (but not GM3) ganglioside to CFTR-silenced cells restored activated β1-integrin, pFAK, and pCAS to near control levels and partially restored (~40%) cell migration. Our results suggest that decreased GM1 in CFTR-silenced cells depresses β1-integrin signaling, which contributes to the delayed wound repair observed in these cells. These findings have implications for the pathology of cystic fibrosis, where altered sphingolipid levels in airway epithelial cells could result in a diminished capacity for wound repair after injury.