Development and characterization of PqsD inhibitors to interrupt cell-to-cell communication in Pseudomonas aeruginosa

Due to the lack of new types of antibiotics and propagating resistance against all available classes, an increasing number of bacterial infections cannot be efficiently treated anymore. Anti-virulent compounds, which target bacterial pathogenesis without affecting cell viability and consequently exert less selection pressure, were recently suggested. Most bacteria control pathogenesis via cell-density-dependent cell-to-cell communication (quorum sensing, QS), which makes QS an appropriate target to pursue an anti-virulence strategy. Besides the widespread acyl homoserine lactone signal molecules, the opportunistic pathogen Pseudomonas aeruginosa applies a rather unique quinolone-based QS system. Thus, inhibitors of PqsD, a key enzyme in the signal molecule biosynthesis, should be developed to specifically combat P. aeruginosa infections. Using a ligand-based approach, the first class of PqsD inhibitors was identified. Simplification and rigidization led to a fragment with high ligand efficiency, which significantly inhibited signal molecule production and biofilm formation in P. aeruginosa. Various methods to characterize the mode of action of PqsD inhibitors were developed, which allowed the proposal of their binding modes. Fine-tuning of the fragment provided PqsD inhibitors with high potential for further improvements. Furthermore, they constitute valuable tools to analyze QS regulation pathways, and to evaluate PqsD as drug target for the treatment of P. aeruginosa.Die Behandlung bakterieller Infektionen wird durch die stagnierende Entwicklung neuer Antibiotika und vermehrter Resistenzbildung zunehmend erschwert. Anti-virulente Verbindungen, welche die Pathogenität der Bakterien absenken ohne deren Lebensfähigkeit zu beeinflussen und damit keinen Selektivitätsdruck ausüben, stellen einen neuen Therapieansatz dar. Die Pathogenität der meisten Bakterien wird durch ein zelldichteabhängiges interzelluläres Kommunikationssystem (Quorum Sensing, QS) gesteuert. Das opportunistische Pathogen Pseudomonas aeruginosa verwendet neben den üblichen Lactonen zusätzlich Chinolone als Signalmoleküle. Dabei ist das Enzym PqsD essentiell für deren Biosynthese und eignet sich daher als Wirkstoff-Target einer Anti-Virulenz Strategie für die spezifische Bekämpfung von P. aeruginosa. In einem Ligand-basierten Ansatz wurde die erste PqsD Inhibitorenklasse identifiziert. Die Verkleinerung und Rigidisierung führten zu einem Fragment, das eine hohe Liganden-effizienz aufweist und die Signalmolekül- und Biofilmbildung in P. aeruginosa hemmt. Mehrere Methoden zur Aufklärung der Wirkungsweisen von PqsD Inhibitoren wurden entwickelt, so dass konkrete Bindungsposen vorgeschlagen werden konnten. Die strukturelle Feinabstimmung des Fragments lieferte leicht weiteroptimierbare PqsD Inhibitoren, die als Tools zur Analyse der QS Regulationswege genutzt werden können und ferner der Beurteilung von PqsD als Drug-Target zur Behandlung von P. aeruginosa dienen

Decreased skin colonization with Malassezia spp. and increased skin colonization with Candida spp. in patients with severe atopic dermatitis

Background: Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease in which patients are sensitized towards a plethora of allergens. The hosts fungal microbiota, the mycobiota, that is believed to be altered in patients suffering from AD acts as such an allergen. The correlation context of specific sensitization, changes in mycobiota and its impact on disease severity however remains poorly understood. Objectives: We aim to enhance the understanding of the specific sensitization towards the mycobiota in AD patients in relation to their fungal skin colonization. Methods: Sensitization pattern towards the Malassezia spp. and Candida albicans of 16 AD patients and 14 healthy controls (HC) were analyzed with the newly developed multiplex-assay ALEX2® and the established singleplex-assay ImmunoCAP®. We compared these findings with the fungal skin colonization analyzed by DNA sequencing of the internal transcribed spacer region 1 (ITS1). Results: Sensitization in general and towards Malassezia spp. and C. albicans is increased in AD patients compared to HC with a quantitative difference in severe AD when compared to mild to moderate AD. Further we saw an association between sensitization towards and skin colonization with Candida spp. yet a negative correlation between sensitization towards and skin colonization with Malassezia spp. Conclusion: We conclude that AD in general and severe AD in particular is associated with increased sensitization towards the hosts own mycobiota. There is positive correlation in Candida spp. skin colonization and negative in Malassezia spp. skin colonization when compared to AD, AD severity as well as to specific sensitization patterns

Nrf2/Keap1-Pathway Activation and Reduced Susceptibility to Chemotherapy Treatment by Acidification in Esophageal Adenocarcinoma Cells

Chronic acid reflux causes cellular damage and inflammation in the lower esophagus. Due to these irritating insults, the squamous epithelium is replaced by metaplastic epithelium, which is a risk factor for the development of esophageal adenocarcinoma (EAC). In this study, we investigated the acid susceptibility in a Barrett’s cell culture in vitro model, using six cell lines, derived from squamous epithelium (EPC1 and EPC2), metaplasia (CP-A), dysplasia (CP-B), and EAC (OE33 and OE19) cells. Cells exposed to acidic pH showed a decreased viability dependent on time, pH, and progression status in the Barrett’s sequence, with the highest acid susceptibility in the squamous epithelium (EPC1 and EPC2), and the lowest in EAC cells. Acid pulsing was accompanied with an activation of the Nrf2/Keap1- and the NFκB-pathway, resulting in an increased expression of HO1—independent of the cellular context. OE33 showed a decreased responsiveness towards 5-FU, when the cells were grown in acidic conditions (pH 6 and pH 5.5). Our findings suggest a strong damage of squamous epithelium by gastroesophageal reflux, while Barrett’s dysplasia and EAC cells apparently exert acid-protective features, which lead to a cellular resistance against acid reflux

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) in association with an adenocarcinoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare disorder and information on this disease is limited, especially with regard to its management and prognosis. It has become generally accepted that DIPNECH is a precursor lesion to pulmonary carcinoid tumors.</p> <p>Case presentation</p> <p>Here we report on a 60-year-old female patient with DIPNECH and an associated pulmonary adenocarcinoma.</p> <p>Conclusion</p> <p>This case contributes to a better understanding of the disorder and its associated pathologies.</p

Controlling Molecular Self-Assembly on an Insulating Surface by Rationally Designing an Efficient Anchor Functionality That Maintains Structural Flexibility

Hauke CM, Bechstein R, Kittelmann M, et al. Controlling Molecular Self-Assembly on an Insulating Surface by Rationally Designing an Efficient Anchor Functionality That Maintains Structural Flexibility. ACS Nano. 2013;7(6):5491-5498.Molecular self-assembly on surfaces is dictated by the delicate balance between intermolecular and molecule-surface interactions. For many insulating surfaces, however, the molecule-surface interactions are weak and rather unspecific. Enhancing these interactions, on the other hand, often puts a severe limit on the achievable structural variety. To grasp the full potential of molecular self-assembly on these application-relevant substrates, therefore, requires strategies for anchoring the molecular building blocks toward the surface in a way that maintains flexibility in terms of intermolecular interaction and relative molecule orientation. Here, we report the design of a site-specific anchor functionality that provides strong anchoring toward the surface, resulting in a well-defined adsorption position. At the same time, the anchor does not significantly interfere with the intermolecular interaction, ensuring structural flexibility. We demonstrate the success of this approach with three molecules from the class of shape-persistent oligo(p-benzamide)s adsorbed onto the calcite(10.4) surface. These molecules have the same aromatic backbone with iodine substituents, providing the same basic adsorption mechanism to the surface calcium cations. The backbone is equipped with different functional groups. These have a negligible influence on the molecular adsorption on the surface but significantly change the Intermolecular interaction. We show that distinctly different molecular structures are obtained that wet the surface due to the strong linker while maintaining variability in the relative molecular orientation. With this study, we thus provide a versatile strategy for increasing the structural richness in molecular self-assembly on Insulating substrates