Women with cystic fibrosis (CF) have a significantly lower life expectancy compared to men, which is indicated by an earlier impairment of lung function due to chronic colonization with biofilm formed by Pseudomonas aeruginosa. There is growing evidence that blood serum concentrations of the steroid sex hormone estradiol (E2) correlate with the occurrence of pulmonary exacerbations in CF but also play a role in the mucoid switch of P. aeruginosa. This study aims to shed light on possible microbiological reasons for sexual dimorphism in CF by investigating the influence of E2 on biofilm formation of P. aeruginosa CF isolates. For this purpose, 10 CF isolates of the respiratory tract derived from different CF patients have been treated with E2 in a microtiter plate biofilm model. Biofilms have been examined by crystal violet assays, field emission scanning electron microscopy (FE-SEM), 3D laser scanning microscopy (LSM), and quorum sensing (QS) reporter assays of the supernatants taken from biofilms. This allowed us to simultaneously investigate the effects of E2 on attached biofilm mass, biofilm ultrastructure, and QS activity. Upon E2 treatment, six out of 10 investigated CF isolates showed an increase of attached biofilm mass, whereas biofilms from two tested non-CF laboratory strains (PAO1 and ATCC19660) did not. Moreover, FE-SEM and 3D LSM analyses of the E2 responsive CF biofilms revealed ultrastructural remodeling of biofilm structure at different scales with increased formation of prominent biofilm spots, enhanced coverage with extracellular polymeric substance (EPS), and extended average surface roughness. QS activity measurements performed in biofilm supernatants via luminescence acyl homoserine lactone (AHL) reporter assays further showed that E2 treatment may also modulate QS signaling, as shown in an E2 sensitive CF isolate. Together, our results suggest the biofilm modulating effects of E2 on various clinical CF isolates that are documented by both biomass and ultrastructural changes of biofilms. The gained new insight into the influence of steroid hormones on P. aeruginosa biofilm phenotypes might pave the way for novel future approaches in personalized medicine based on the patients’ sex and hormonal status.

The fabrication, characterization and application of a nanoporous Silicon Rugate Filter (pSiRF) loaded with an enzymatically degradable polymer is reported as a bare eye detection optical sensor for enzymes of pathogenic bacteria, which is devoid of any dyes. The nanopores of pSiRF were filled with poly(lactic acid) (PLA), which, upon enzymatic degradation, resulted in a change in the effective refractive index of the pSiRF film, leading to a readily discernible color change of the sensor. The shifts in the characteristic fringe patterns before and after the enzymatic reaction were analyzed quantitatively by Reflectometric Interference Spectroscopy (RIfS) to estimate the apparent kinetics and its dependence on enzyme concentration. A clear color change from green to blue was observed by the bare eye after PLA degradation by proteinase K. Moreover, the color change was further confirmed in measurements in bacterial suspensions of the pathogen Pseudomonas aeruginosa (PAO1) as well as in situ in the corresponding bacterial supernatants. This study highlights the potential of the approach in point of care bacteria detection.

<p>Women with Cystic Fibrosis (CF) have a significantly lower life expectancy compared to men, which is indicated by an earlier impairment of lung function due to chronic colonization of pathogenic bacteria like <em>Pseudomonas aeruginosa</em> (PA). Reasons for this “CF gender gap” until now have not yet been fully clarified and are assumed to be multifactorial.</p> <p>This study aims to shed light on the contribution of sex hormones to the CF-Gender gap considering microbial endocrinology. Therefor the study investigates whether the sex hormone estradiol, whose blood serum concentrations are significantly fluctuating within the female cycle and during pregnancy, has a regulatory influence on the development of PA biofilms in the context of CF.</p> <p>For that purpose, biofilms of PA isolates from CF-patients are treated <em>in vitro</em> with various estradiol concentrations and are examined in a comparative study quantitatively regarding the total biomass, <em>e.g.</em> via crystal violet staining, and qualitatively, <em>e.g.</em> via scanning electron microscopy, to characterize the ultrastructure of the biofilm.</p> <p>We observed that estradiol induces biofilm-forming capacity of CF-PA-isolates with respect to the total biomass and modulates the biofilm structure especially concerning the distribution and clustering of bacteria.</p> <p>The observed <em>in vitro</em> correlation between estradiol concentration and extent of biofilm growth provides a possible microbiological explanation for gender differences in CF disease progression.</p> <p>These insights and further research on possible underlying mechanisms might be relevant in the long-term for new approaches in personalized treatment for female CF patients.</p> <p><strong>Acknowledgement</strong></p> <p>This work is supported by a financial grant from Mukoviszidose Institut gGmbH, Bonn, the research and development arm of the German Cystic Fibrosis Association Mukoviszidose e.V., the Christiane Herzog foundation. We further thank the Equal Opportunities Office of the University Siegen as well as the DAAD PPP Frankreich (Project-ID 55976814) for financial support.</p> <p> </p>