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

Mining, Analysis and Targeted Activation of Secondary Metabolite Gene Clusters in Streptomyces bambergiensis

The discovery of new antibiotics is one of the most urgent tasks facing scientists today. The escalating rate of resistant microbes creates a constant need for new or improved drugs. With the recent progress in genome sequencing a new world is opening up as researchers can explore bacterial antibiotic biosynthesis gene clusters that are normally silent under laboratory conditions. Waking up these silent gene clusters harbours the potential of novel drug discoveries to fight microbial infections, cancer or other major life-threatening conditions. In this work, genetic potential of Streptomyces bambergiensis, known producer of antibacterial antibiotic moenomycin, was investigated. Whole genome sequence of S. bambergiensis showed that it has, in addition to moenomycin cluster, 28 secondary metabolite biosynthetic gene clusters, including a giant polyketide synthase (PKS) gene cluster composed of 30 genes and spanning over 190 kb. The product of this gene cluster is unknown and likely not produced under laboratory conditions. First, moenomycin gene cluster was inactivated in S. bambergiensis by deletion in order to eliminate antibacterial background activity. Next, constitutive expression of the regulatory gene, a LuxR family transcriptional regulator, from the PKS gene cluster was accomplished, leading to the production of a compound with inhibitory activity against Bacillus subtilis. Preliminary analysis suggested that this may be a new compound that can be further studied as a potential antibiotic

Ventilator-induced lung-injury in mouse models: Is there a trap?

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 DownloadVentilator-induced lung injury (VILI) is a serious acute injury to the lung tissue that can develop during mechanical ventilation of patients. Due to the mechanical strain of ventilation, damage can occur in the bronchiolar and alveolar epithelium resulting in a cascade of events that may be fatal to the patients. Patients requiring mechanical ventilation are often critically ill, which limits the possibility of obtaining patient samples, making VILI research challenging. In vitro models are very important for VILI research, but the complexity of the cellular interactions in multi-organ animals, necessitates in vivo studies where the mouse model is a common choice. However, the settings and duration of ventilation used to create VILI in mice vary greatly, causing uncertainty in interpretation and comparison of results. This review examines approaches to induce VILI in mouse models for the last 10 years, to our best knowledge, summarizing methods and key parameters presented across the studies. The results imply that a more standardized approach is warranted. Keywords: Acute lung injury; Animal models; Mouse studies; Ventilator-induced lung injury.Landspitali research fun