Antagonistic Pleiotropy in the Bifunctional Surface Protein FadL (OmpP1) during Adaptation of Haemophilus influenzae to Chronic Lung Infection Associated with Chronic Obstructive Pulmonary Disease

Abstract

Nontypeable Haemophilus influenzae is an important pathogen in patients with chronic obstructive pulmonary disease (COPD). To elucidate the bacterial pathways undergoing in vivo evolutionary adaptation, we compared bacterial genomes collected over time from 13 COPD patients and identified recurrent genetic changes arising in independent bacterial lineages colonizing different patients. Besides finding changes in phase-variable genes, we found recurrent loss-of-function mutations in the ompP1 (fadL) gene. We show that loss of OmpP1/FadL function reduces this bacterium’s ability to infect cells via the hCEACAM1 epithelial receptor but also increases its resistance to bactericidal fatty acids enriched within the COPD lung, suggesting a case of antagonistic pleiotropy that restricts ΔfadL strains’ niche. These results show how H. influenzae adapts to host-generated inflammatory mediators in the COPD airways.

Molecular signatures of non-typeable Haemophilus influenzae lung adaptation in paediatric chronic lung disease

“…The remaining SSR indels occurred in the haemoglobin-haptoglobin binding protein B-encoding gene hgpB, 316 which is involved in NP colonisation and iron acquisition (51), and lic3A, which encodes a 317 lipooligosaccharide (LOS) sialyltransferase that facilitates NTHi colonisation in different 318 anatomical sites (52,53). 319 Our genetic findings concur with the recent studies, which found that phase variation in lic3A, 320 hsdM3 and hgpB are common in NTHi isolates retrieved from COPD airways (17,46). In 321 addition to the hgpB SSR variant in 60068 BAL Hi1 that truncates the protein from 992 to 12 322 residues, a non-synonymous SNP (HgpBArg407Lys) was seen in 60295 BAL Hi1.…”

“…Previous studies have identified deleterious ompP1 mutations in ~33% of COPD 338 isolates, and in-frame ompP2 mutations (i.e. missense SNPs and indels) in ~20% of COPD 339 isolates (17,46). Similarly, we identified an in-frame ompP2 mutation in the 65001 BAL Hi1 340 isolate that occurred in the extracellular loop six motif (56) and increased OmpP2 length by 341 three amino acids.…”

“…In this study, we aimed to identify signals of NTHi 297 pathoadaptation to the lower airways using 12 paired isogenic strains retrieved from the 298 upper (NP) and the lower (BAL fluid) airways of 11 paediatric patients with CLSD or 299 bronchiectasis. Similar studies have employed WGS to document the genome-wide changes 300 leading to chronic adaptation and persistence of NTHi retrieved from COPD sputum in adults 301 (17,46). The current work expands on these prior studies by examining both the genomic and 302 transcriptomic profiles of NTHi adaptation in children's airways.…”

“…Biochemical profiles in COPD airways (e.g. fatty acids345 with bactericidal activity against NTHi wild-type strains)(46) are potentially different to those 346 present in paediatric bronchiectasis or CSLD airways, which may explain the greater selective347 pressure for OmpP1 inactivation in COPD airways. Further work is needed to document the 348 prevalence of ompP1 mutations in a larger paediatric lung isolate cohort to examine whether 349 diseased paediatric airways do in fact impart different OmpP1 pressures on NTHi compared 350 with isolates from COPD airways.…”

Preclinical Evaluation of the Antimicrobial-Immunomodulatory Dual Action of Xenohormetic Molecules against Haemophilus influenzae Respiratory Infection

“…The three molecules reduced NTHi bacterial viability in a dose-dependent manner, quercetin being the one with the lowest MIC observed ( Figure 1B and Figure S1B). Genomic heterogeneity is a known feature for NTHi [44][45][46], which may lead to variable polyphenol susceptibility among strains, as is shown for other antimicrobials [33]. We evaluated the effect of quercetin, myricetin, and punicalagin on three NTHi clinical strains isolated from COPD sputum samples and belonging to different clonal types [45]; their viability decreased when exposed to polyphenols, with some MIC variations among them (Table S2).…”