Beigelman A, Goss CW, Wang J, Srinivasan M, Boomer J, Zhou Y, Bram S, Casper TJ, Coverstone AM, Kanchongkittiphon W, Kuklinski C, Storch GA, Schechtman KB, Castro M, and Bacharier LB
Background: Early life respiratory syncytial virus (RSV) bronchiolitis is a significant risk factor for childhood asthma. In vitro and in vivo studies suggested that decreasing levels of airway matrix metalloproteinase (MMP)-9 during RSV bronchiolitis may be associated with clinical benefits., Objective: To investigate whether azithromycin therapy during severe RSV bronchiolitis reduces upper airway MMP-9 levels, whether upper airway MMP-9 levels correlate with upper airway interleukin IL-8 levels, and whether MMP-9 level reduction is associated with reduced post-RSV recurrent wheeze (RW)., Methods: A total of 200 otherwise healthy 1- to 18-month-old infants hospitalized with RSV bronchiolitis were randomized into a double-blind, placebo-controlled trial of oral azithromycin (10 mg/kg daily for 7 days followed by 5 mg/kg daily for 7 days) or placebo. Infants were followed for 2 to 4 years for the outcome of RW (3 or more wheezing episodes). Nasal lavage samples for MMP-9 levels were obtained at baseline, day 14 (end of the study treatment), and after 6 months., Results: Upper airway MMP-9 levels were highly correlated with IL-8 levels at all 3 time points: randomization, day 14, and 6 months (r = 0.80; P < .0001 for all time points). MMP-9 levels were similar between treatment groups at randomization, were lower on day 14 among children treated with azithromycin (P = .0085), but no longer different after 6 months. MMP-9 levels at baseline and change from baseline to day 14 were not associated with the development of RW (P = .49, .39, respectively)., Conclusion: Azithromycin therapy in children hospitalized with RSV bronchiolitis had a short-term anti-inflammatory effect in reducing upper airway MMP-9 levels. However, the reduction in MMP-9 levels did not relate to subsequent RW post-RSV., Trial Registration: This study is a secondary analysis of the Azithromycin to Prevent Wheezing following severe RSV bronchiolitis-II clinical trial registered at Clinicaltrials.gov (NCT02911935)., Competing Interests: Disclosures Dr Beigelman reports receiving grant support from the US-Israel Binational Science Foundation (BSF); serving as an advisor and speaker for Sanofi; and serving as a DSMB member of OM Pharma. Dr Kanchongkittiphon reports serving as a speaker for GlaxoSmithKline, Takeda, AstraZeneca, Viatris, and Organon. Dr Bacharier reports serving as a member of the GINA Science Committee; receiving grants from the National Institutes of Health/National Institute of Allergy and Infectious Diseases/National Heart, Lung, and Blood Institute; receiving personal fees from GlaxoSmithKline, Genentech/Novartis, Merck, Teva, Boehringer Ingelheim, AstraZeneca, Avillion, WebMD/Medscape, Sanofi/Regeneron, Vectura, Circassia, OM Pharma, Recludix, and Kinaset; serving for DSMB from AstraZeneca, DBV Technologies, Aravax, and Vertex; and receiving royalties from Elsevier, outside the submitted work. Dr Castro reports receiving research support from the American Lung Association, AstraZeneca, GlaxoSmithKline, National Institutes of Health, Novartis, PCORI, Pulmatrix, Sanofi-Aventis, and Shionogi; serving as a consultant for Genentech, Novartis, Sanofi-Aventis, and Teva; receiving speaker fees from AstraZeneca, Genentech, GlaxoSmithKline, Regeneron Pharmaceuticals, Inc., Sanofi, and Teva; and receiving royalties from Elsevier. The remaining authors have no conflicts of interest to report., (Copyright © 2024 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)