Repurposing bacterial lysates: an inhalation approach for respiratory infection management
Joana Pinto-da-Silva1, Melibea Berzosa2, Alberto Delgado-López3, Carlos Gamazo3 & Ana Grenha1,4
1Centre for Marine Sciences, Universidade do Algarve, Campus Gambelas, Faro, 8005-139, Portugal
2Wellcome Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast, BT9 5AL, United Kingdom;
3Department of Microbiology, University of Navarra, Pamplona, 31008, Spain
4Faculdade de Ciências e Tecnologia, Universidade do Algarve, Campus Gambelas, Faro, 8005-139, Portugal
Summary
Bacterial lysates (BL) are commonly used as immunomodulators in respiratory tract infection prevention. However, there is conflicting evidence for clinical efficacy, with the typical practice of oral administration limiting the potential to generate adequate lung protection. To improve the prospect of BL delivery inducing a beneficial immune response, a novel approach involving inhalation is proposed. Spray-dried locust bean gum (LBG) microparticles (MP) were used to encapsulate BL and confer suitable properties for lung delivery. Furthermore, as a galactomannan, LBG will facilitate targeting of antigen presenting cells in the lungs through interaction with mannose surface receptors. The preservation of BL antigenicity was confirmed by direct agglutination using specific antibodies. A release assay was performed upon dry powder which was aerosolized onto a membrane in contact with a dissolution medium to represent lung conditions. A sustained release was observed with 80% release of BL after 6 h, reaching 85% release over 24 h. These data encourage the approach of repurposing BL for inhalation, with the aim of preventing respiratory infections.