How Does Airway Surface Liquid Composition Vary in Different Pulmonary Diseases, and How Can We Use This Knowledge to Model Microbial Infections?

Abstract

Growth environment greatly alters many facets of pathogen physiology, including pathogenesis and antimicrobial tolerance. The importance of host-mimicking environments for attaining an accurate picture of pathogen behaviour is widely recognised. Whilst this recognition has translated into the extensive development of artificial cystic fibrosis (CF) sputum medium, attempts to mimic the growth environment in other respiratory disease states have been completely neglected. The composition of the airway surface liquid (ASL) in different pulmonary diseases is far less well characterised than CF sputum, making it very difficult for researchers to model these infection environments. In this review, we discuss the components of human ASL, how different lung pathologies affect ASL composition, and how different pathogens interact with these components. This will provide researchers interested in mimicking different respiratory environments with the information necessary to design a host-mimicking medium, allowing for better understanding of how to treat pathogens causing infection in these environments.

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

“…These distinctions include much higher mucin and glucose concentrations compared to those in cystic fibrosis sputum [58–61]. The SVAM medium recipe was developed following an extensive review of existing literature [62]. The effect of each SVAM component on the growth and biofilm formation of P. aeruginosa , K. pneumoniae and C. albicans is shown in Figs S1–S3 in the Supplementary Material, along with accompanying Supplementary Methods.…”

“…In medical device biofilms, this layer consists of proteins such as fibronectin and laminin and polysaccharides [74], all of which are present within FBS [75]. Our SVAM medium was designed following an extensive review of published literature [62]. It contains many components absent from standard laboratory growth medium such as mucin, DNA, metals, GlcNAc, albumin and lysozyme which provide nutrition or alter the gene expression of microbial pathogens in the pulmonary inflammatory disease environment [76–83] and induce antimicrobial tolerance [78, 84–88].…”