Lluch, M. | bioRxiv Science

bioRxiv2025

Targeting Pseudomonas aeruginosa Ventilator-associated pneumonia with a non-antibiotic and biolfilm-disrupting Live Biotherapeutic: Preclinical Safety and Efficacy study

Background.Ventilator-associated pneumonia (VAP) is the second most common hospital-acquired infection and is associated with high morbidity and mortality. The insertion of the endotracheal tube (ETT) compromises the hosts bronchial defenses and facilitates the formation of microbial biofilms and VAP. Although antibiotics remain the cornerstone treatment, their efficacy is often compromised by poor biofilm penetration and the prevalence of multidrug-resistant bacteria. This reveals the need to develop novel non-antibiotic therapeutic strategies. We engineered a non-pathogenic strain of the pulmonary bacteria Mycoplasma pneumoniae CV2 to express anti-biofilm and bactericidal enzymes (VAP platform). The therapeutic effect was validated in a murine model of Pseudomonas aeruginosa infection and ex vivo in ETTs of patients with P. aeruginosa-induced VAP. Methods.We evaluated the safety of an improved version of CV2 (CV8, Mycochassis) in a miniature pig model, and its efficacy with the VAP therapeutic platform (CV8_VAP) in a piglet model of P. aeruginosa-induced VAP. CV8_VAP was administered via intralobe instillation or nebulization. We assessed the platforms ability to degrade biofilms formed on ETTs in vivo and its impact on the airway microbiota. We evaluated bacterial load in the lungs, inflammatory responses, histopathological and the clinical outcomes to provide a comprehensive characterization of therapeutic efficacy and safety. Findings.VAP platform reduced biofilm thickness and P. aeruginosa load in ETTs and lungs, with the nebulized route showing enhanced efficacy. CV8_VAP contributed on microbiome diversity restoration. Inflammatory markers in the lung were markedly decreased, suggesting a local immunomodulatory effect. Interpretation.These findings support that CV8_VAP as a promising, non-antibiotic therapeutic strategy for treating VAP caused by P. aeruginosa. Funding.The project that gave rise to these results has received funding from "La Caixa" Foundation (HR18-00058), and the European Research Council under the European Unions Horizon 2020 research and innovation program (670216).

synthetic biology↗

bioRxiv2020

Lox'd in translation: Contradictions in the nomenclature surrounding common lox site mutants and their implications in experiments

The removal of unwanted genetic material is a key aspect in many synthetic biology efforts, and often requires preliminary knowledge of which genomic regions are dispensable. Typically, these efforts are guided by transposon mutagenesis studies, coupled to deep-sequencing (TnSeq) to identify insertion points and gene essentiality. However, epistatic interactions can cause unforeseen changes in essentiality after the deletion of a gene, leading to the redundancy of these essentiality maps. Here, we present LoxTnSeq, a new methodology to generate and catalogue libraries of genome reduction mutants. LoxTnSeq combines random integration of lox sites by transposon mutagenesis, and the generation of mutants via cre recombinase, catalogued via deep-sequencing. When LoxTnSeq was applied to the naturally genome reduced bacterium Mycoplasma pneumoniae, we obtained a mutant pool containing 285 unique deletions. These deletions spanned from >50 bp to 28 Kb, which represent 21% of the total genome. LoxTnSeq also highlighted large regions of non-essential genes that could be removed simultaneously, and other non-essential regions that could not, providing a guide for future genome reductions.

bioengineering↗