Biology subjects

Bragonzi, A.

Publications and source records attributed to Bragonzi, A..

5 recordsLinked to original sources

bioRxiv2023

DeltaF508-Cftr mutation in genetically diverse Collaborative Cross mice yields novel disease-relevant phenotypes for cystic fibrosis

Mutations of Cystic Fibrosis Transmembrane conductance Regulator (CFTR) lead to Cystic Fibrosis (CF), but the substantial phenotypic variations are determined by non-CFTR allelic diversity. To map novel disease phenotypes in a CF mouse model, we used Collaborative Cross (CC) mice, a highly genetically diverse mouse resource population.{Delta} F508-Cftr homozygosity produced a fully penetrant lethal phenotype by eight weeks in two CC lines. The lethality of CC006{Delta}F508/{Delta}F508 was fully prenatal while CC037{Delta}F508/{Delta}F508 showed either prenatal or postnatal lethality. Novel phenotypes of CC037{Delta}F508/{Delta}F508 were revealed early in life including respiratory and systemic inflammatory profiles, and blood, bone marrow, pancreas, heart, and reproductive tract pathologies. Severe intestinal blockage was observed as common in other CF mouse models. These results suggest that the exploration of CF disease phenotypes in a mouse population with diverse genetic profiles is needed to map the genetic origin of currently unidentified disease traits and their potential translation to humans.

pathology↗

bioRxiv2022

Linking CFTR modulators to opportunistic bacterial infections in cystic fibrosis

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators improve clinical outcomes with variable efficacy in patients with cystic fibrosis (CF). However, changes produced by bacterial persistence and adaptation in addition to antibiotic regimens could influence CFTR modulator efficacy and vice versa and hence clinical outcomes. We first evaluated the effects of ivacaftor (IVA), lumacaftor (LUM), tezacaftor, elexacaftor and elexacaftor/tezacaftor/ivacaftor (ETI), alone or combined with antibiotics, on sequential Staphylococcus aureus and Pseudomonas aeruginosa CF isolates. IVA and ETI showed the most potent direct antimicrobial activity against S. aureus, while P. aeruginosa was not affected. Additive effects or synergies were observed between the CFTR modulators and antibiotics against both S. aureus and P. aeruginosa, independently of the stage of colonization. IVA and LUM were the most effective in potentiating antibiotic activity against S. aureus, while IVA and ETI enhanced mainly polymyxins activity against P. aeruginosa. Next, we evaluated the effect of P. aeruginosa pneumonia on the pharmacokinetics of IVA in mice. The time-concentration curves of IVA and its metabolites in plasma, lung and epithelial lining fluid were influenced by P. aeruginosa infection. The area under the concentration-time curve showed that airway exposure to IVA was greater in infected than non-infected mice. These results suggest that CFTR modulators can have direct antimicrobial properties and/or enhance antibiotic activity against S. aureus and P. aeruginosa. Furthermore, bacterial infection impacts the IVA concentration and airway exposure, potentially affecting its efficacy. Our findings suggest optimizing host- and pathogen-directed drug regimens to improve efficacy for personalized treatment.

microbiology↗

bioRxiv2020

A new model of chronic Mycobacterium abscessus lung infection in immunocompetent mice

Pulmonary infections caused by Mycobacterium abscessus (MA) have increased over recent decades affecting individuals with underlying pathologies such as chronic obstructive pulmonary disease, bronchiectasis and, especially, cystic fibrosis. The lack of a representative and standardized model of chronic infection in mice has limited steps forward in the field of MA pulmonary infection. To overcome this challenge we refined the method of agar beads to establish MA chronic infection in immunocompetent mice. We evaluated bacterial count, lung pathology and markers of inflammation and we performed longitudinal studies with magnetic resonance imaging (MRI) up to three months after MA infection. In this model, MA was able to establish a persistent lung infection up to two months and with minimal systemic spread. Lung histopathological analysis revealed granulomatous inflammation around bronchi characterized by the presence of neutrophils, lymphocytes and aggregates of vacuolated foamy cells, mimicking the damage observed in humans. Furthermore, MA lung lesions were successfully monitored for the first time by MRI. The availability of this murine model and the introduction of the successfully longitudinal monitoring of the murine lung lesions with MRI pave the way for further investigations on the impact of MA pathogenesis and the efficacy of novel treatments.

microbiology↗

bioRxiv2020

The small RNA ErsA plays a role in the regulatory network of Pseudomonas aeruginosa pathogenicity in airways infection

Bacterial small RNAs play a remarkable role in the regulation of functions involved in host-pathogen interaction. ErsA is a small RNA of Pseudomonas aeruginosa that contributes to the regulation of bacterial virulence traits such as biofilm formation and motility. Shown to take part in a regulatory circuit under the control of the envelope stress response sigma factor {sigma}22, ErsA targets post-transcriptionally the key virulence-associated gene algC. Moreover, ErsA contributes to biofilm development and motility through the post-transcriptional modulation of the transcription factor AmrZ. Intending to evaluate the regulatory relevance of ErsA in the pathogenesis of respiratory infections, we analyzed the impact of ErsA-mediated regulation on the virulence potential of P. aeruginosa and the stimulation of the inflammatory response during the infection of bronchial epithelial cells and a murine model. Furthermore, we assessed ErsA expression in a collection of P. aeruginosa clinical pulmonary isolates and investigated the link of ErsA with acquired antibiotic resistance by generating an ersA gene deletion mutant in a multidrug-resistant P. aeruginosa strain which has long been adapted in the airways of a cystic fibrosis (CF) patient. Our results show that the ErsA-mediated regulation is relevant for the P. aeruginosa pathogenicity during acute infection and contributes to the stimulation of the host inflammatory response. Besides, ErsA could be subjected to selective pressure for P. aeruginosa patho-adaptation and acquirement of resistance to antibiotics commonly used in clinical practice during chronic CF infections. Our findings establish the role of ErsA as an important regulatory element in the host-pathogen interaction. Author summaryPseudomonas aeruginosa is one of the most critical multi-drug resistant opportunistic pathogen in humans, able to cause both lethal acute and chronic lung infections. Thorough knowledge of the regulatory mechanisms involved in the establishment and persistence of the airways infections by P. aeruginosa remains elusive. Emerging candidates as molecular regulators of pathogenesis in P. aeruginosa are small RNAs, which act post-transcriptionally as signal transducers of host cues. Known for being involved in the regulation of biofilm formation and responsive to envelope stress response, we show that the small RNA ErsA can play regulatory roles in acute infection, stimulation of host inflammatory response, mechanisms of acquirement of antibiotic resistance and adaptation during the chronic lung infections of cystic fibrosis patients. Elucidating the complexity of the networks regulating host-pathogen interaction is crucial to identify novel targets for future therapeutic applications.

microbiology↗

bioRxiv2020

The persistence of Nontypeable Haemophilus influenzae fuels airway inflammation

*Nontypeable Haemophilus influenzae (NTHi) is commonly isolated from airway of cystic fibrosis (CF) patients. However, to what extent NTHi persistence contributes to the lung inflammatory burden during CF chronic airway disease is controversial. Here, we aimed at determining the pathological role of NTHi persistence in a cohort of CF patients and in a newly generated mouse model of NTHi persistence. In our study cohort, we found that CF patients chronically colonized by NTHi had significantly higher levels of IL-8 and CXCL1 than those who were not colonized. To better define the impact of NTHi persistence in fuelling inflammatory response, we developed a new mouse model using both laboratory and CF clinical strains. NTHi persistence was associated with chronic inflammation of the lung, characterized by recruitment of neutrophils and cytokine release (KC, G-CFS, IL-6 and IL-17A) at 2 and 14 days postinfection. An increased burden of T cell mediated response (CD4+ and {gamma}{delta} cells) and higher levels of matrix metalloproteinase 9, known to be associated with tissue remodelling, were observed at 14 days post-infection. Of note we found that both CD4+IL-17+ cells and levels of IL-17 cytokine were enriched in mice at advanced stage of NTHi chronic infection. Moreover, by immunohistochemistry we found CD3+, B220+ and CXCL-13+ cells localized in bronchus-associated lymphoid tissue-like structures at day 14. Our results demonstrate that NTHi persistence exerts a pro-inflammatory activity in the human and murine lung, and could therefore contribute to the exaggerated burden of lung inflammation in CF patients.

microbiology↗