Lactobacillus rhamnosus probiotic prevents airway function deterioration and promotes gut microbiome resilience in a murine asthma model

ABSTRACT

Allergic asthma is a highly prevalent inflammatory disease of the lower airways, clinically characterized by airway hyperreactivity and deterioration of airway function. Immunomodulatory probiotic bacteria are increasingly being explored to prevent asthma development, alone or in combination with other treatments.

In this study, wild-type and recombinant probiotic Lactobacillus rhamnosus GR-1 were tested as preventive treatment of experimental allergic asthma in mice. Recombinant L. rhamnosus GR-1 was designed to produce the major birch pollen allergen Bet v 1, to promote allergen-specific immunomodulation. Administration of wild-type and recombinant L. rhamnosus GR-1 prevented the development of airway hyperreactivity. Recombinant L. rhamnosus GR-1 also prevented elevation of airway total cell counts, lymphocyte counts and lung IL-1β levels, while wild-type L. rhamnosus GR-1 inhibited airway eosinophilia. Of note, a shift in gut microbiome composition was observed after asthma development, which correlated with the severity of airway inflammation and airway hyperreactivity. In the groups that received L. rhamnosus GR-1, this asthma-associated shift in gut microbiome composition was not observed, indicating microbiome-modulating effects of this probiotic.

These data demonstrate that L. rhamnosus GR-1 can prevent airway function deterioration in allergic asthma. Bet v 1 expression by L. rhamnosus GR-1 further contributed to lower airway inflammation, although not solely through the expected reduction in T helper 2-associated responses, suggesting involvement of additional mechanisms. The beneficial effects of L. rhamnosus GR-1 correlate with increased gut microbiome resilience, which in turn is linked to protection of airway function, and thus further adds support to the existence of a gut-lung axis.

KEYWORDS:

• Probiotics
• allergy
• mouse model
• gut microbiome
• airway hyperreactivity
• gut-lung axis
• lactobacillus
• microbiota
• airway inflammation
• birch pollen

Abbreviations

AHR	=	Airway hyperreactivity
ASV	=	Amplicon sequence variant
BALF	=	Bronchoalveolar lavage fluid
BP	=	Birch pollen
FEV0.2%	=	Forced expiratory volume at 0.2 s as percentage of baseline
Ig	=	Immunoglobulin
L. rhamnosus	=	Lactobacillus rhamnosus
LGR-1	=	Lactobacillus rhamnosus GR-1
MAMP	=	Microbe-associated molecular pattern
MLN	=	Mesenteric lymph node
PC20-FEV%	=	Provocative concentration of methacholine causing a 20% fall in FEV
PCoA	=	Principal coordinate analysis
Rn	=	Airway resistance
Th	=	T helper
Treg	=	Regulatory T cell

Acknowledgements

We acknowledge the valuable technical help of Tine Verhoeven, Jolien Mennens, Rob Dockx, Jonathan Cremer, Eline Oerlemans, Stijn Wittouck, Ahmad Kasran, and Anne-Charlotte Jonckheere during the course of this study.

Authors contributions

I.S., J.C., Jozef V, S.L., M.P., and S.S. were involved in the conception of the study. I.S., J.C., M.P., S.L., S.S., and W.V.B. contributed to the design of the experimental work and/or the writing and the critical revision of the manuscript. I.S., W.V.B., F.D., and Jeroen V. performed the experimental work and processed the data. I.S., J.C., S.S., M.P., S.L., W.V.B., and Jeroen V. interpreted the data. All authors reviewed and corrected the manuscript.

Disclosure of potential conflicts of interest

M.P. consults for academic and industrial representatives in the field of microbiome and probiotics. She holds no share in any probiotic companies nor receives any profit-sharing linked to the field. Her clients had no role in drafting this manuscript or the decision to submit the work for publication. Other authors declare no conflict of interest.

Data availability

Sequencing data are available at the European Nucleotide Archive with the accession number PRJEB33230 (https://www.ebi.ac.uk/ena/data/view/PRJEB33230).

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

I.S. was supported by IWT-SB-Vlaanderen for her PhD scholarship, and by IOF POC (University of Antwerp) and IWT SBO financing during her postdoctoral work at the University of Antwerp. S.S. was the recipient of a KU Leuven Research Council grant (PDMK/14/189). S.L. was supported by the Fund for Scientific Research (FWO) Vlaanderen postdoctoral grant, the research grant KaN 28960, and the IWT-SBO ProCure Grant (IWT150052). M.P. was the recipient of an FWO Vlaanderen postdoctoral grant. J.C. was supported by a grant from FWO Vlaanderen. WVB is supported by a Dehousse scholarship from the University of Antwerp.