Azithromycin has lung barrier protective effects in a cell model mimicking ventilator-induced lung injury.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadAzithromycin (AZM) is a broad-spectrum antibiotic widely used to treat infections. AZM also has been shown to have anti-inflammatory and immunomodulatory functions unrelated to its antibacterial activity that contribute to the effectiveness of this drug in chronic respiratory diseases. The mechanisms behind these beneficial effects are not yet fully elucidated. We have previously shown that AZM enhances barrier integrity of bronchial epithelial cells and directs them towards epidermal differentiation. In this study, we analyzed the effect of AZM pre-treatment of human bronchial and alveolar derived cell lines on mechanical stress in a cyclical pressure air-liquid interface device (CPAD) that models the disruption of the epithelial barrier with increased inflammatory response in lung tissue, which is associated with ventilator-induced lung injury (VILI). Immunostaining and electron microscopy showed that barrier integrity of the epithelium was compromised by cyclically stressing the cells but maintained when cells had been pre-treated with AZM. Lamellar body formation was revealed in AZM pre-treated cells, possibly further supporting the barrier-enhancing effects. RNA sequencing showed that the inflammatory response was attenuated by AZM treatment before cyclical stress. YKL-40, an emerging inflammatory marker, increased both due to cyclical stress and upon AZM treatment. These data confirm the usefulness of the CPAD to model ventilator-induced lung injury and suggest that AZM has barrier protective and immunomodulatory effects, attenuating the inflammatory response during mechanical stress, and might therefore be lung protective during mechanical ventilation. The model could be used to assess further drug candidates that influence barrier integrity and modulate inflammatory response. Keywords: YKL-40; airway epithelium; azithromycin; immunomodulation; ventilator-induced lung injury.Icelandic Research Council Landspitali University Hospital science fun

Innovative in vitro method to study ventilator induced lung injury.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadMechanical ventilation (MV) is a life-saving therapy for critically ill patients, alleviating the work of breathing and supporting adequate gas exchange. However, MV can cause ventilator induced lung injury (VILI) by baro/volu- and atelectrauma, even lead to acute respiratory distress syndrome (ARDS), and substantially augment mortality. There is a need for specific biomarkers and novel research platforms for VILI/ARDS research to study these detrimental disorders and seek ways to avoid or prevent them. Previous in vitro studies on bronchial epithelium, cultured in air-liquid interface (ALI) conditions, have generally utilized static or constant pressure. We have developed a Cyclical Pressure ALI Device (CPAD) that enables cyclical stress on ALI cultured human bronchial cells, with the aim of mimicking the effects of MV. Using CPAD we were able to analyze differentially expressed VILI/ARDS and innate immunity associated genes along with increased expression of associated proteins. CPAD provides an easy and accessible way to analyze functional and phenotypic changes that occur during VILI and may provide a platform for future drug testing.Technology development fund - Icelandic research council University of Iceland Land-spitali, University Hospital, Science fun

Methane Clumped Isotopes: Progress and Potential for a New Isotopic Tracer

The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding petroleum systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. In general, clumped isotope measurements indicate plausible formation temperatures for abiotic, thermogenic, and microbial methane in many geological environments, which is encouraging for the further development of this measurement as a geothermometer, and as a tracer for the source of natural gas reservoirs and emissions. We also highlight, however, instances where clumped isotope derived temperatures are higher than expected, and discuss possible factors that could distort equilibrium formation temperature signals. In microbial methane from freshwater ecosystems, in particular, clumped isotope values appear to be controlled by kinetic effects, and may ultimately be useful to study methanogen metabolism

Azithromycin induces epidermal differentiation and multivesicular bodies in airway epithelia.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadBACKGROUND: Azithromycin (Azm) is a macrolide recognized for its disease-modifying effects and reduction in exacerbation of chronic airway diseases. It is not clear whether the beneficial effects of Azm are due to its anti-microbial activity or other pharmacological actions. We have shown that Azm affects the integrity of the bronchial epithelial barrier measured by increased transepithelial electrical resistance. To better understand these effects of Azm on bronchial epithelia we have investigated global changes in gene expression. METHODS: VA10 bronchial epithelial cells were treated with Azm and cultivated in air-liquid interface conditions for up to 22 days. RNA was isolated at days 4, 10 and 22 and analyzed using high-throughput RNA sequencing. qPCR and immunostaining were used to confirm key findings from bioinformatic analyses. Detailed assessment of cellular changes was done using microscopy, followed by characterization of the lipidomic profiles of the multivesicular bodies present. RESULTS: Bioinformatic analysis revealed that after 10 days of treatment genes encoding effectors of sterol and cholesterol metabolism were prominent. Interestingly, expression of genes associated with epidermal barrier differentiation, KRT1, CRNN, SPINK5 and DSG1, increased significantly at day 22. Together with immunostaining, these results suggest an epidermal differentiation pattern. We also found that Azm induced the formation of multivesicular and lamellar bodies in two different airway epithelial cell lines. Lipidomic analysis revealed that Azm was entrapped in multivesicular bodies linked to different types of lipids, most notably palmitate and stearate. Furthermore, targeted analysis of lipid species showed accumulation of phosphatidylcholines, as well as ceramide derivatives. CONCLUSIONS: Taken together, we demonstrate how Azm might confer its barrier enhancing effects, via activation of epidermal characteristics and changes to intracellular lipid dynamics. These effects of Azm could explain the unexpected clinical benefit observed during Azm-treatment of patients with various lung diseases affecting barrier function.Icelandic Research Council EpiEndo Pharmaceuticals, Reykjavik, Icelan

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]