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Air pollution, nasal microbiota, and bronchiolitis: understanding their interplay through a multilevel approach.

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Title: Air pollution, nasal microbiota, and bronchiolitis: understanding their interplay through a multilevel approach.
Authors: Cafora M; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy; Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy., Severgnini M; Institute of Biomedical Technologies, National Research Council, Milan, Italy., Favero C; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy., Ceccarani C; Institute of Biomedical Technologies, National Research Council, Milan, Italy., Hoxha M; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy., Consolandi C; Institute of Biomedical Technologies, National Research Council, Milan, Italy., Camboni T; Institute of Biomedical Technologies, National Research Council, Milan, Italy., Pinatel E; Institute of Biomedical Technologies, National Research Council, Milan, Italy., Milani G; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy; Pediatric Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy., Luganini A; Department of Life Science and System Biology, University of Turin, Turin, Italy., Bollati V; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy; Occupational Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy., Pistocchi A; Department of Medical Biotechnology and Translational Medicine, University of Milan, Italy. Electronic address: anna.pistocchi@unimi.it., Ferrari L; Department of Clinical Sciences and Community Health, Dipartimento di Eccellenza 2023-2027, University of Milan, Italy; Occupational Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy. Electronic address: luca.ferrarari@unimi.it.
Source: Environmental research [Environ Res] 2025 Dec 01; Vol. 286 (Pt 3), pp. 123014. Date of Electronic Publication: 2025 Oct 03.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Elsevier Country of Publication: Netherlands NLM ID: 0147621 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1096-0953 (Electronic) Linking ISSN: 00139351 NLM ISO Abbreviation: Environ Res Subsets: MEDLINE
Imprint Name(s): Publication: <2000- > : Amsterdam : Elsevier
Original Publication: New York, Academic Press.
MeSH Terms: Bronchiolitis*/microbiology , Bronchiolitis*/epidemiology , Particulate Matter*/toxicity , Particulate Matter*/adverse effects , Microbiota* , Air Pollution*/adverse effects , Air Pollutants*/toxicity , Nose*/microbiology, Humans ; Animals ; Infant ; Male ; Female ; Zebrafish ; Case-Control Studies
Abstract: Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Bronchiolitis is a severe acute lower respiratory tract condition in infants, with respiratory syncytial virus (RSV) infection being a leading cause. Despite extensive research, the factors influencing the severity of bronchiolitis remain poorly understood. Environmental factors, including exposure to particulate matter (PM) with diameters ≤10 μm (PM 10 ) and ≤2.5 μm (PM 2.5 ), are suspected of exacerbating RSV bronchiolitis by enhancing inflammatory pathways. We previously demonstrated that PM 10 and PM 2.5 levels during the three weeks preceding pediatric emergency department admission (the -3rd week AVG) are associated with increased bronchiolitis severity in infants. The bacterial nasal microbiota (bNM), lying at the interface between the environment and the airways, has emerged as a key modulator of host immune and inflammatory responses, potentially influencing the pathogenesis and course of bronchiolitis in response to environmental triggers. This study examines the effects of PM 10 and PM 2.5 on bNM composition in the context of bronchiolitis and explores the role of bacterial extracellular vesicles (bEVs) as potential modulators of inflammatory processes after PM exposure, using a zebrafish model to monitor the inflammatory response in vivo. We conducted a case-control study involving 110 infants diagnosed with bronchiolitis (cases) and 49 matched healthy controls (HC), revealing significant differences in bNM composition between cases and HC. The -3rd week average (AVG) of PM exposure influenced the bNM, with cases showing a higher relative abundance of Haemophilus influenzae (Hi), becoming more pronounced as PM levels increased. Injection of Hi-derived bEVs into zebrafish embryos induced a robust pro-inflammatory response, characterized by neutrophil recruitment and upregulation of inflammatory gene expression. Our findings reveal that air pollution alters bNM composition, potentially worsening bronchiolitis in infants through inflammatory processes. This study underscores the important role of bEVs in bronchiolitis pathogenesis, offering new insights into the interplay between environmental factors, microbiota, and host immunity in respiratory infections.
(Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.)
Contributed Indexing: Keywords: Bacterial nasal microbiota; Bronchiolitis; Inflammation; Innate immunity; Particulate matter; Zebrafish
Substance Nomenclature: 0 (Particulate Matter)
0 (Air Pollutants)
Entry Date(s): Date Created: 20251005 Date Completed: 20251030 Latest Revision: 20251030
Update Code: 20251031
DOI: 10.1016/j.envres.2025.123014
PMID: 41046972
Database: MEDLINE
Description
Abstract:Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.<br />Bronchiolitis is a severe acute lower respiratory tract condition in infants, with respiratory syncytial virus (RSV) infection being a leading cause. Despite extensive research, the factors influencing the severity of bronchiolitis remain poorly understood. Environmental factors, including exposure to particulate matter (PM) with diameters ≤10 μm (PM <subscript>10</subscript> ) and ≤2.5 μm (PM <subscript>2.5</subscript> ), are suspected of exacerbating RSV bronchiolitis by enhancing inflammatory pathways. We previously demonstrated that PM <subscript>10</subscript> and PM <subscript>2.5</subscript> levels during the three weeks preceding pediatric emergency department admission (the -3rd week AVG) are associated with increased bronchiolitis severity in infants. The bacterial nasal microbiota (bNM), lying at the interface between the environment and the airways, has emerged as a key modulator of host immune and inflammatory responses, potentially influencing the pathogenesis and course of bronchiolitis in response to environmental triggers. This study examines the effects of PM <subscript>10</subscript> and PM <subscript>2.5</subscript> on bNM composition in the context of bronchiolitis and explores the role of bacterial extracellular vesicles (bEVs) as potential modulators of inflammatory processes after PM exposure, using a zebrafish model to monitor the inflammatory response in vivo. We conducted a case-control study involving 110 infants diagnosed with bronchiolitis (cases) and 49 matched healthy controls (HC), revealing significant differences in bNM composition between cases and HC. The -3rd week average (AVG) of PM exposure influenced the bNM, with cases showing a higher relative abundance of Haemophilus influenzae (Hi), becoming more pronounced as PM levels increased. Injection of Hi-derived bEVs into zebrafish embryos induced a robust pro-inflammatory response, characterized by neutrophil recruitment and upregulation of inflammatory gene expression. Our findings reveal that air pollution alters bNM composition, potentially worsening bronchiolitis in infants through inflammatory processes. This study underscores the important role of bEVs in bronchiolitis pathogenesis, offering new insights into the interplay between environmental factors, microbiota, and host immunity in respiratory infections.<br /> (Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.)
ISSN:1096-0953
DOI:10.1016/j.envres.2025.123014