Challenges and opportunities in the development of novel antimicrobial therapeutics for cystic fibrosis

Chronic respiratory infection is the primary driver of mortality in individuals with cystic fibrosis (CF). Existing drug screening models utilised in preclinical antimicrobial development are unable to mimic the complex CF respiratory environment. Consequently, antimicrobials showing promising activity in preclinical models often fail to translate through to clinical efficacy in people with CF. Model systems used in CF anti-infective drug discovery and development range from antimicrobial susceptibility testing in nutrient broth, through to 2D and 3D in vitro tissue culture systems and in vivo models. No single model fully recapitulates every key aspect of the CF lung. To improve the outcomes of people with CF (PwCF) it is necessary to develop a set of preclinical models that collectively recapitulate the CF respiratory environment to a high degree of accuracy. Models must be validated for their ability to mimic aspects of the CF lung and associated lung infection, through evaluation of biomarkers that can also be assessed following treatment in the clinic. This will give preclinical models greater predictive power for identification of antimicrobials with clinical efficacy. The landscape of CF is changing, with the advent of modulator therapies that correct the function of the CFTR protein, while antivirulence drugs and phage therapy are emerging alternative treatments to chronic infection. This review discusses the challenges faced in current antimicrobial development pipelines, including the advantages and disadvantages of current preclinical models and the impact of emerging treatments

Cytogenetic analysis of adult T-Cell leukemia/ lymphoma: evaluation of a Caribbean cohort

Adult T-cell leukemia/lymphoma (ATLL) is a rare and highly aggressive type of peripheral T-cell lymphoma associated with human T-lymphotropic virus, type I (HTLV-I) infection. ATLL has a long latency and only a small percentage of HTLV-I infected individuals develop ATLL, suggesting the requirement of additional genetic events for neoplastic transformation of HTLV-I infected lymphocytes. The disease is endemic in several regions of the world, in particular, southwestern Japan and the Caribbean basin. The clinical features of Caribbean ATLL have been reported to differ from Japanese cases, includ- ing a younger age at diagnosis, higher frequency of the lymphomatous subtype, and a more aggressive clinical course [1–7]. A number of publications have described the cytogenetic profile of Japanese ATLL [8–11]; however, cytogenetic data on Caribbean ATLL are limited [5,6]. In this study, we assessed the cytogenetic alterations in a large series of Caribbean ATLL cases to investigate whether the differences in the types and frequencies of karyotype abnormalities account for the reported differ- ences in clinical presentation and outcome between Japanese and Caribbean patients

Sulfur-Polymer Nanoparticles: Preparation and Antibacterial Activity.

High sulfur content polymers prepared by inverse vulcanization have many reported potential applications, including as novel antimicrobial materials. High sulfur content polymers usually have limited water-solubility and dispersibility due to their hydrophobic nature, which could limit the development of their applications. Herein, we report the formulation of high sulfur content polymeric nanoparticles by a nanoprecipitation and emulsion-based method. High sulfur content polymeric nanoparticles were found to have an inhibitory effect against important bacterial pathogens, including Gram-positive methicillin-resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Salt-stable particles were formulated with the addition of a surfactant, which did not inhibit the antibacterial activity of the polymeric particles. Furthermore, the polymeric nanoparticles were found to inhibit S. aureus biofilm formation and exhibited low cytotoxicity against mammalian liver cells. Interaction of the polymeric particles with cellular thiols could be a potential mechanism of action against bacterial cells, as demonstrated by reaction with cysteine as a model thiol. The findings presented demonstrate methods of preparing aqueous dispersions of high sulfur content polymeric nanoparticles that could have useful biological applications

Increased pathogenicity of pneumococcal serotype 1 is driven by rapid autolysis and release of pneumolysin

Streptococcus pneumoniae serotype 1 is the predominant cause of invasive pneumococcal disease in sub-Saharan Africa, but the mechanism behind its increased invasiveness is not well understood. Here, we use mouse models of lung infection to identify virulence factors associated with severe bacteraemic pneumonia during serotype-1 (ST217) infection. We use BALB/c mice, which are highly resistant to pneumococcal pneumonia when infected with other serotypes. However, we observe 100% mortality and high levels of bacteraemia within 24 hours when BALB/c mice are intranasally infected with ST217. Serotype 1 produces large quantities of pneumolysin, which is rapidly released due to high levels of bacterial autolysis. This leads to substantial levels of cellular cytotoxicity and breakdown of tight junctions between cells, allowing a route for rapid bacterial dissemination from the respiratory tract into the blood. Thus, our results offer an explanation for the increased invasiveness of serotype 1

Development of liquid culture media mimicking the conditions of sinuses and lungs in cystic fibrosis and health [version 2; peer review: 2 approved]

The respiratory tract is a compartmentalised and heterogenous environment. The nasopharynx and sinuses of the upper airways have distinct properties from the lungs and these differences may shape bacterial adaptation and evolution. Upper airway niches act as early colonisation sites for respiratory bacterial pathogens, including those, such as Pseudomonas aeruginosa, that can go on to establish chronic infection of the lungs in people with cystic fibrosis (CF). Despite the importance of upper airway environments in facilitating early adaptation to host environments, currently available in vitro models for study of respiratory infection in CF focus exclusively on the lungs. Furthermore, animal models, widely used to bridge the gap between in vitro systems and the clinical scenario, do not allow the upper and lower airways to be studied in isolation. We have developed a suite of culture media reproducing key features of the upper and lower airways, for the study of bacterial adaptation and evolution in different respiratory environments. For both upper and lower airway-mimicking media, we have developed formulations that reflect airway conditions in health and those that reflect the altered environment of the CF respiratory tract. Here, we describe the development and validation of these media and their use for study of genetic and phenotypic adaptations in P. aeruginosa during growth under upper or lower airway conditions in health and in CF

Identification of two distinct phylogenomic lineages and model strains for the 2 understudied cystic fibrosis lung pathogen Burkholderia multivorans.

Burkholderia multivorans is the dominant Burkholderia pathogen recovered from lung infection in people with cystic fibrosis. However, as an understudied pathogen there are knowledge gaps in relation to its population biology, phenotypic traits and useful model strains. A phylogenomic study of B. multivorans was undertaken using a total of 283 genomes, of which 73 were sequenced and 49 phenotypically characterized as part of this study. Average nucleotide identity analysis (ANI) and phylogenetic alignment of core genes demonstrated that the B. multivorans population separated into two distinct evolutionary clades, defined as lineage 1 (n=58 genomes) and lineage 2 (n=221 genomes). To examine the population biology of B. multivorans, a representative subgroup of 77 B. multivorans genomes (28 from the reference databases and the 49 novel short-read genome sequences) were selected based on multilocus sequence typing (MLST), isolation source and phylogenetic placement criteria. Comparative genomics was used to identify B. multivorans lineage-specific genes – ghrB_1 in lineage 1 and glnM_2 in lineage 2 – and diagnostic PCRs targeting them were successfully developed. Phenotypic analysis of 49 representative B. multivorans strains showed considerable inter-strain variance, but the majority of the isolates tested were motile and capable of biofilm formation. A striking absence of B. multivorans protease activity in vitro was observed, but no lineage-specific phenotypic differences were demonstrated. Using phylogenomic and phenotypic criteria, three model B. multivorans CF strains were identified, BCC0084 (lineage 1), BCC1272 (lineage 2a) and BCC0033 lineage 2b, and their complete genome sequences determined. B. multivorans CF strains BCC0033 and BCC0084, and the environmental reference strain, ATCC 17616, were all capable of short-term survival within a murine lung infection model. By mapping the population biology, identifying lineage-specific PCRs and model strains, we provide much needed baseline resources for future studies of B. multivorans

Measurement-induced state transitions in a superconducting qubit: Beyond the rotating wave approximation

Many superconducting qubit systems use the dispersive interaction between the qubit and a coupled harmonic resonator to perform quantum state measurement. Previous works have found that such measurements can induce state transitions in the qubit if the number of photons in the resonator is too high. We investigate these transitions and find that they can push the qubit out of the two-level subspace, and that they show resonant behavior as a function of photon number. We develop a theory for these observations based on level crossings within the Jaynes-Cummings ladder, with transitions mediated by terms in the Hamiltonian that are typically ignored by the rotating wave approximation. We find that the most important of these terms comes from an unexpected broken symmetry in the qubit potential. We confirm the theory by measuring the photon occupation of the resonator when transitions occur while varying the detuning between the qubit and resonator