Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype

the WASP Study Group; Steven L Taylor; Collin R Brooks; Lucy Pembrey; Sarah K Manning; Levi Elms; Harriet Mpairwe; Camila A Figueiredo; Aida Y Oviedo; Martha Chico; Jeroen Burmanje; Hajar Ali; Irene Nambuya; Pius Tumwesige; Steven Robertson; Charlotte E Rutter; Karin van Veldhoven; Susan M Ring; Mauricio L Barreto; Philip J Cooper; Álvaro A Cruz; Neil Pearce; Geraint B Rogers; Jeroen Douwes

doi:10.1136/thorax-2025-222965

Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype

the WASP Study Group, Steven L Taylor, Collin R Brooks, Lucy Pembrey^*, Sarah K Manning, Levi Elms, Harriet Mpairwe, Camila A Figueiredo, Aida Y Oviedo, Martha Chico, Jeroen Burmanje, Hajar Ali, Irene Nambuya, Pius Tumwesige, Steven Robertson, Charlotte E Rutter, Karin van Veldhoven, Susan M Ring, Mauricio L Barreto, Philip J CooperÁlvaro A Cruz, Neil Pearce, Geraint B Rogers, Jeroen Douwes

^*Corresponding author for this work

Research output: Contribution to journal › Article (Academic Journal) › peer-review

Abstract

Background:
Asthma is an umbrella diagnosis encompassing distinct pathophysiological mechanisms. While a global problem, our understanding of the interplay between respiratory microbiology and airway inflammation is largely from populations in high-income settings. As a result, treatment approaches align poorly with asthma characteristics in less studied populations.

Objective:
To identify conserved and geographically distinct relationships between airway inflammation and microbiota characteristics in young people with and without asthma.

Methods:
We conducted a cross-sectional study performing inflammatory phenotyping, microbiota analysis and enumeration of total bacteria, Haemophilus influenzae and Moraxella catarrhalis on 488 induced sputum samples from participants from Brazil (asthma: 68; non-asthma: 8), Ecuador (asthma: 89; non-asthma: 30), Uganda (asthma: 61; non-asthma: 8), New Zealand (asthma: 129; non-asthma: 58) and the UK (asthma: 25; non-asthma: 20). Microbiota characteristics were compared by country, asthma status and inflammatory characteristics, adjusting for age and sex.

Results:
Asthma inflammatory phenotypes and microbiology differed between countries, with Uganda characterised by higher neutrophils, microbial diversity and bacterial abundance. Comparison of airway inflammation with microbiota characteristics showed conserved relationships across centres, with airway neutrophil proportion explaining variance in microbiota Bray-Curtis dissimilarity (p<0.001) and being positively associated with bacterial abundance, including H. influenzae and M. catarrhalis load (all p<0.05). In contrast, eosinophil proportion was less strongly associated with microbiota dissimilarity (p=0.033) and only associated with Streptococcus abundance. Country-specific associations between airway inflammation and microbiology were evident.

Conclusion:
Both airway inflammation and microbiology varied geographically in young people with asthma. Associations between microbiota characteristics and neutrophilic phenotype were conserved.

Original language	English
Article number	thorax-2025-222965
Number of pages	11
Journal	Thorax
Early online date	30 Jan 2026
DOIs	https://doi.org/10.1136/thorax-2025-222965
Publication status	E-pub ahead of print - 30 Jan 2026

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Publisher Copyright:
© Author(s) (or their employer(s)) 2026.

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the WASP Study Group, Taylor, S. L., Brooks, C. R., Pembrey, L., Manning, S. K., Elms, L., Mpairwe, H., Figueiredo, C. A., Oviedo, A. Y., Chico, M., Burmanje, J., Ali, H., Nambuya, I., Tumwesige, P., Robertson, S., Rutter, C. E., van Veldhoven, K., Ring, S. M., Barreto, M. L., ... Douwes, J. (2026). Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype. Thorax, Article thorax-2025-222965. Advance online publication. https://doi.org/10.1136/thorax-2025-222965

@article{443fddabf04a4d54968b01691e6c800f,

title = "Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype",

abstract = "Background: Asthma is an umbrella diagnosis encompassing distinct pathophysiological mechanisms. While a global problem, our understanding of the interplay between respiratory microbiology and airway inflammation is largely from populations in high-income settings. As a result, treatment approaches align poorly with asthma characteristics in less studied populations. Objective: To identify conserved and geographically distinct relationships between airway inflammation and microbiota characteristics in young people with and without asthma. Methods: We conducted a cross-sectional study performing inflammatory phenotyping, microbiota analysis and enumeration of total bacteria, Haemophilus influenzae and Moraxella catarrhalis on 488 induced sputum samples from participants from Brazil (asthma: 68; non-asthma: 8), Ecuador (asthma: 89; non-asthma: 30), Uganda (asthma: 61; non-asthma: 8), New Zealand (asthma: 129; non-asthma: 58) and the UK (asthma: 25; non-asthma: 20). Microbiota characteristics were compared by country, asthma status and inflammatory characteristics, adjusting for age and sex. Results: Asthma inflammatory phenotypes and microbiology differed between countries, with Uganda characterised by higher neutrophils, microbial diversity and bacterial abundance. Comparison of airway inflammation with microbiota characteristics showed conserved relationships across centres, with airway neutrophil proportion explaining variance in microbiota Bray-Curtis dissimilarity (p<0.001) and being positively associated with bacterial abundance, including H. influenzae and M. catarrhalis load (all p<0.05). In contrast, eosinophil proportion was less strongly associated with microbiota dissimilarity (p=0.033) and only associated with Streptococcus abundance. Country-specific associations between airway inflammation and microbiology were evident. Conclusion: Both airway inflammation and microbiology varied geographically in young people with asthma. Associations between microbiota characteristics and neutrophilic phenotype were conserved.",

author = "\{the WASP Study Group\} and Taylor, \{Steven L\} and Brooks, \{Collin R\} and Lucy Pembrey and Manning, \{Sarah K\} and Levi Elms and Harriet Mpairwe and Figueiredo, \{Camila A\} and Oviedo, \{Aida Y\} and Martha Chico and Jeroen Burmanje and Hajar Ali and Irene Nambuya and Pius Tumwesige and Steven Robertson and Rutter, \{Charlotte E\} and \{van Veldhoven\}, Karin and Ring, \{Susan M\} and Barreto, \{Mauricio L\} and Cooper, \{Philip J\} and Cruz, \{{\'A}lvaro A\} and Neil Pearce and Rogers, \{Geraint B\} and Jeroen Douwes",

note = "Publisher Copyright: {\textcopyright} Author(s) (or their employer(s)) 2026.",

year = "2026",

month = jan,

day = "30",

doi = "10.1136/thorax-2025-222965",

language = "English",

journal = "Thorax",

issn = "0040-6376",

publisher = "BMJ Publishing Group",

}

the WASP Study Group, Taylor, SL, Brooks, CR, Pembrey, L, Manning, SK, Elms, L, Mpairwe, H, Figueiredo, CA, Oviedo, AY, Chico, M, Burmanje, J, Ali, H, Nambuya, I, Tumwesige, P, Robertson, S, Rutter, CE, van Veldhoven, K, Ring, SM, Barreto, ML, Cooper, PJ, Cruz, ÁA, Pearce, N, Rogers, GB & Douwes, J 2026, 'Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype', Thorax. https://doi.org/10.1136/thorax-2025-222965

TY - JOUR

T1 - Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype

AU - the WASP Study Group

AU - Taylor, Steven L

AU - Brooks, Collin R

AU - Pembrey, Lucy

AU - Manning, Sarah K

AU - Elms, Levi

AU - Mpairwe, Harriet

AU - Figueiredo, Camila A

AU - Oviedo, Aida Y

AU - Chico, Martha

AU - Burmanje, Jeroen

AU - Ali, Hajar

AU - Nambuya, Irene

AU - Tumwesige, Pius

AU - Robertson, Steven

AU - Rutter, Charlotte E

AU - van Veldhoven, Karin

AU - Ring, Susan M

AU - Barreto, Mauricio L

AU - Cooper, Philip J

AU - Cruz, Álvaro A

AU - Pearce, Neil

AU - Rogers, Geraint B

AU - Douwes, Jeroen

PY - 2026/1/30

Y1 - 2026/1/30

N2 - Background: Asthma is an umbrella diagnosis encompassing distinct pathophysiological mechanisms. While a global problem, our understanding of the interplay between respiratory microbiology and airway inflammation is largely from populations in high-income settings. As a result, treatment approaches align poorly with asthma characteristics in less studied populations. Objective: To identify conserved and geographically distinct relationships between airway inflammation and microbiota characteristics in young people with and without asthma. Methods: We conducted a cross-sectional study performing inflammatory phenotyping, microbiota analysis and enumeration of total bacteria, Haemophilus influenzae and Moraxella catarrhalis on 488 induced sputum samples from participants from Brazil (asthma: 68; non-asthma: 8), Ecuador (asthma: 89; non-asthma: 30), Uganda (asthma: 61; non-asthma: 8), New Zealand (asthma: 129; non-asthma: 58) and the UK (asthma: 25; non-asthma: 20). Microbiota characteristics were compared by country, asthma status and inflammatory characteristics, adjusting for age and sex. Results: Asthma inflammatory phenotypes and microbiology differed between countries, with Uganda characterised by higher neutrophils, microbial diversity and bacterial abundance. Comparison of airway inflammation with microbiota characteristics showed conserved relationships across centres, with airway neutrophil proportion explaining variance in microbiota Bray-Curtis dissimilarity (p<0.001) and being positively associated with bacterial abundance, including H. influenzae and M. catarrhalis load (all p<0.05). In contrast, eosinophil proportion was less strongly associated with microbiota dissimilarity (p=0.033) and only associated with Streptococcus abundance. Country-specific associations between airway inflammation and microbiology were evident. Conclusion: Both airway inflammation and microbiology varied geographically in young people with asthma. Associations between microbiota characteristics and neutrophilic phenotype were conserved.

AB - Background: Asthma is an umbrella diagnosis encompassing distinct pathophysiological mechanisms. While a global problem, our understanding of the interplay between respiratory microbiology and airway inflammation is largely from populations in high-income settings. As a result, treatment approaches align poorly with asthma characteristics in less studied populations. Objective: To identify conserved and geographically distinct relationships between airway inflammation and microbiota characteristics in young people with and without asthma. Methods: We conducted a cross-sectional study performing inflammatory phenotyping, microbiota analysis and enumeration of total bacteria, Haemophilus influenzae and Moraxella catarrhalis on 488 induced sputum samples from participants from Brazil (asthma: 68; non-asthma: 8), Ecuador (asthma: 89; non-asthma: 30), Uganda (asthma: 61; non-asthma: 8), New Zealand (asthma: 129; non-asthma: 58) and the UK (asthma: 25; non-asthma: 20). Microbiota characteristics were compared by country, asthma status and inflammatory characteristics, adjusting for age and sex. Results: Asthma inflammatory phenotypes and microbiology differed between countries, with Uganda characterised by higher neutrophils, microbial diversity and bacterial abundance. Comparison of airway inflammation with microbiota characteristics showed conserved relationships across centres, with airway neutrophil proportion explaining variance in microbiota Bray-Curtis dissimilarity (p<0.001) and being positively associated with bacterial abundance, including H. influenzae and M. catarrhalis load (all p<0.05). In contrast, eosinophil proportion was less strongly associated with microbiota dissimilarity (p=0.033) and only associated with Streptococcus abundance. Country-specific associations between airway inflammation and microbiology were evident. Conclusion: Both airway inflammation and microbiology varied geographically in young people with asthma. Associations between microbiota characteristics and neutrophilic phenotype were conserved.

U2 - 10.1136/thorax-2025-222965

DO - 10.1136/thorax-2025-222965

M3 - Article (Academic Journal)

SN - 0040-6376

JO - Thorax

JF - Thorax

M1 - thorax-2025-222965

ER -

Airway microbiota in young people across four continents differ by country, asthma status and inflammatory phenotype

Abstract

Bibliographical note

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