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

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; WASP Study Group

doi:10.1136/thorax-2025-222965

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

Thorax. 2026 Jan 30:thorax-2025-222965. doi: 10.1136/thorax-2025-222965. Online ahead of print.

Authors

Steven L Taylor^{1

2}, Collin R Brooks³, Lucy Pembrey⁴, Sarah K Manning¹, Levi Elms¹, Harriet Mpairwe⁵, Camila A Figueiredo⁶, Aida Y Oviedo⁷, Martha Chico⁷, Jeroen Burmanje³, Hajar Ali³, Irene Nambuya⁵, Pius Tumwesige⁵, Steven Robertson⁸, Charlotte E Rutter⁸, Karin van Veldhoven⁸, Susan M Ring^{9

10}, Mauricio L Barreto^{6

11}, Philip J Cooper^{7

12

13}, Álvaro A Cruz¹⁴, Neil Pearce⁸, Geraint B Rogers^#¹, Jeroen Douwes^#³; WASP Study Group

Collaborators

WASP Study Group:
Neil Pearce, Lucy Pembrey, Steven Robertson, Karin van Veldhoven, Charlotte E Rutter, Sinead Langan, Sarah Thorne, Donna Davoren, John Henderson, Susan Ring, Elizabeth Brierley, Sophie Fitzgibbon, Simon Scoltock, Amanda Hill, Alvaro Cruz, Camila Figueiredo, Mauricio Barreto, Cinthia Vila Nova Santana, Gabriela Pimentel Pinheiro, Gilvaneide Lima, Valmar Bião Lima, Jamille Fernandes, Tamires Cana Brasil Carneiro, Candace Andrade, Gerson Queiroz, Anaque Pires, Milca Silva, Jéssica Cerqueira, Philip Cooper, Martha Chico, Cristina Ardura-Garcia, Araceli Falcones, Aida Y Oviedo, Andrea Zambrano, Jeroen Douwes, Collin Brooks, Hajar Ali, Jeroen Burmanje, Harriet Mpairwe, Irene Nambuya, Pius Tumwesige, Milly Namutebi, Marble Nnaluwooza, Mike Mukasa

Affiliations

¹ Microbiome and Host Health Programme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia.
² College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
³ Research Centre for Hauora and Health, Massey University, Wellington, New Zealand.
⁴ London School of Hygiene & Tropical Medicine, London, UK lucy.pembrey@lshtm.ac.uk.
⁵ MRC/UVRI and LSHTM Uganda Research Unit, Entebbe, Uganda.
⁶ Federal University of Bahia Salvador, Salud, Brazil.
⁷ Fundación Ecuatoriana Para Investigación en Salud, Quito, Ecuador.
⁸ London School of Hygiene & Tropical Medicine, London, UK.
⁹ Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, Bristol, UK.
¹⁰ MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK.
¹¹ Center for Data and Knowledge Integration for Health, Fiocruz, Bahia, Bahia, Brazil.
¹² Institute of Infection and Immunity, St George's University of London, London, UK.
¹³ School of Medicine, Universidad Internacional del Ecuador, Quito, Pichincha, Ecuador.
¹⁴ Medicine, Federal University of Bahia, Salvador, Bahia, Brazil.

^# Contributed equally.

PMID: 41617609
DOI: 10.1136/thorax-2025-222965

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.

Keywords: Asthma; Asthma Epidemiology; Asthma Mechanisms; Microbiota.