Elastin degradation product isodesmosine is a chemoattractant for Pseudomonas aeruginosa

Role of elastic fiber degradation in disease pathogenesis

Elastin is a crucial extracellular matrix protein that provides structural integrity to tissues. Crosslinked elastin and associated microfibrils, named elastic fiber, contribute to biomechanics by providing the elasticity required for proper function. During aging and disease, elastic fiber can be progressively degraded and since there is little elastin synthesis in adults, degraded elastic fiber is not regenerated. There is substantial evidence linking loss or damage of elastic fibers to the clinical manifestation and pathogenesis of a variety of diseases. Disruption of elastic fiber networks by hereditary mutations, aging, or pathogenic stimuli results in systemic ailments associated with the production of elastin degradation products, inflammatory responses, and abnormal physiology. Due to its longevity, unique mechanical properties, and widespread distribution in the body, elastic fiber plays a central role in homeostasis of various physiological systems. While pathogenesis related to elastic fiber degradation has been more thoroughly studied in elastic fiber rich tissues such as the vasculature and the lungs, even tissues containing relatively small quantities of elastic fibers such as the eyes or joints may be severely impacted by elastin degradation. Elastic fiber degradation is a common observation in certain hereditary, age, and specific risk factor exposure induced diseases representing a converging point of pathological clinical phenotypes which may also help explain the appearance of co-morbidities. In this review, we will first cover the role of elastic fiber degradation in the manifestation of hereditary diseases then individually explore the structural role and degradation effects of elastic fibers in various tissues and organ systems. Overall, stabilizing elastic fiber structures and repairing lost elastin may be effective strategies to reverse the effects of these diseases.

Pseudomonas aeruginosa PAO1 Is Attracted to Bovine Bile in a Novel, Cystic Fibrosis-Derived Bronchial Epithelial Cell Model

Cystic fibrosis (CF) is a life-threatening, inherited, multi-organ disease that renders patients susceptible throughout their lives to chronic and ultimately deteriorating protracted pulmonary infections. Those infections are dominated in adulthood by the opportunistic pathogen, Pseudomonas aeruginosa (Pa). As with other advancing respiratory illnesses, people with CF (pwCF) also frequently suffer from gastroesophageal reflux disease (GERD), including bile aspiration into the lung. GERD is a major co-morbidity factor in pwCF, with a reported prevalence of 35–81% in affected individuals. Bile is associated with the early acquisition of Pa in CF patients and in vitro studies show that it causes Pa to adopt a chronic lifestyle. We hypothesized that Pa is chemoattracted to bile in the lung environment. To evaluate, we developed a novel chemotaxis experimental system mimicking the lung environment using CF-derived bronchial epithelial (CFBE) cells which allowed for the evaluation of Pa (strain PAO1) chemotaxis in a physiological scenario superior to the standard in vitro systems. We performed qualitative and quantitative chemotaxis tests using this new experimental system, and microcapillary assays to demonstrate that bovine bile is a chemoattractant for Pa and is positively correlated with bile concentration. These results further buttress the hypothesis that bile likely contributes to the colonization and pathogenesis of Pa in the lung, particularly in pwCF.

The Arginine Catabolism-Derived Amino Acid L-ornithine Is a Chemoattractant for Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common, opportunistic bacterial pathogen among patients with cystic fibrosis, asthma, and chronic obstructive pulmonary disease. During the course of these diseases, l-ornithine, a non-proteinogenic amino acid, becomes more abundant. P. aeruginosa is chemotactic towards other proteinogenic amino acids. Here, we evaluated the chemotaxis response of P. aeruginosa towards l-ornithine. Our results show that l-ornithine serves as a chemoattractant for several strains of P. aeruginosa, including clinical isolates, and that the chemoreceptors involved in P. aeruginosa PAO1 are PctA and PctB. It seems likely that P. aeruginosa’s chemotactic response to l-ornithine might be a common feature and thus could potentially contribute to pathogenesis processes during colonization and infection scenarios.

Cystic fibrosis disease severity correlates with plasma levels of desmosine and isodesmosine, biomarkers of elastin degradation

Novel methodological approaches now demonstrate that the unique elastin degradation products desmosine and isodesmosine are detectable in plasma of cystic fibrosis patients and correlate to lung function, exacerbation frequency and disease progression http://bit.ly/2VwZOcx.