Pulmonary Surfactant Promotes Virulence Gene Expression and Biofilm Formation in Klebsiella pneumoniae

Abstract

The interactions between and the host environment at the site of infection are largely unknown. Pulmonary surfactant serves as an initial point of contact for inhaled bacteria entering the lung and is thought to contain molecular cues that aid colonization and pathogenesis. To gain insight into this ecological transition, we characterized the transcriptional response of MGH 78578 to purified pulmonary surfactant. This work revealed changes within the transcriptome that likely contribute to host colonization, adaptation, and virulence Notable transcripts expressed under these conditions include genes involved in capsule synthesis, lipopolysaccharide modification, antibiotic resistance, biofilm formation, and metabolism. In addition, we tested the contributions of other surfactant-induced transcripts to survival using engineered isogenic KPPR1 deletion strains in a murine model of acute pneumonia. In these infection studies, we identified the MdtJI polyamine efflux pump and the ProU glycine betaine ABC transporter to be significant mediators of survival within the lung and confirmed previous evidence for the importance of leucine synthesis to bacterial survival during infection. Finally, we determined that pulmonary surfactant promoted type 3 fimbria-mediated biofilm formation in and identified two surfactant constituents, phosphatidylcholine and cholesterol, that drive this response. This study provides novel insight into the interactions occurring between and the host at an important infection site and demonstrates the utility of purified lung surfactant preparations for dissecting host-lung pathogen interactions.

Stenotrophomonas maltophilia Differential Gene Expression in Synthetic Cystic Fibrosis Sputum Reveals Shared and Cystic Fibrosis Strain-Specific Responses to the Sputum Environment

“…2 and Table 1). We speculate that some of the "stress" imposed by SCFM2 is utilization of lipids and head-group moieties whose metabolic pathways generate endogenous stress, since similar responses are also seen for P. aeruginosa and Klebsiella pneumonia during exposure to lung surfactant (55,56), and by P. aeruginosa when exposed to choline and its metabolites (57). Furthermore, expression of amino acid and polyamine efflux pumps was shared between all three S. maltophilia strains, suggesting that growth in SCFM2 results in metabolic stress due to the accumulation of excess nitrogen, likely from amino acid (Fig.…”

“…Transcription of the polyamine efflux pump genes, the predicted mdtJ and mdtI orthologs, increased several 100-fold under these conditions. The expression of mdtJI was recently shown to be important for K. pneumoniae survival in a mouse model of acute pneumonia (62). It is therefore plausible that the expression of this pump could similarly influence S. maltophilia fitness in the context of the CF lung.…”

“…Total RNA was then extracted from these samples using a Zymo Research RNA miniprep kit. Residual genomic DNA was removed from each sample through DNase I treatment (NEB), and the RNA was repurified using a Qiagen RNeasy kit, as we have done previously (62). The quality of each resulting RNA sample was assessed by using an Agilent bioanalyzer and quantified with a Qubit fluorometer.…”

Antibody-recruiting protein-catalyzed capture agents to combat antibiotic-resistant bacteria

“…The specicity of cy(LLFFF) towards MrkA in particular was further interrogated by affinity tests to KPPR1 cells in which the gene encoding MrkA was knocked out (along with mrkB and mrkC). 64 Western blot analysis conrmed that this modied KPPR1 strain does not produce MrkA ( Fig. 5B inset, full blot in Fig.…”

Differential modes of crosslinking establish spatially distinct regions of peptidoglycan in Caulobacter crescentus

“…For example, in a mouse model of lung infection by Klebsiella pneumoniae, lysozyme M knockout mice did not survive beyond 72 h post infection, whereas 25% of wild-type mice survived up to 120 h (Markart et al, 2004). Transcriptomic analysis of K. pneumoniae exposed to pulmonary surfactant showed that relative to controls, interaction with lung secretions increased ybiS LD-transpeptidase expression (Willsey et al, 2018). Upregulation of ybiS expression may be part of a general envelope stress response, similar to the increase of E. coli ldtD transcription during the Cpx envelope stress response (Bernal-Cabas et al, 2015); alternatively, it may be a specific program for modulating peptidoglycan composition to avoid killing by the host lysozyme defense.…”