BMC Pulm Med. 2021 Aug 13;21(1):261. doi: 10.1186/s12890-021-01634-z.

ABSTRACT

BACKGROUND: While lung transplant (LTX) can be an effective therapy to provide the survival benefit in selected populations, post-transplant outcome in LTX recipients with bronchiectasis other than cystic fibrosis (CF) has been less studied. Pseudomonas aeruginosa, often associated with exacerbations in bronchiectasis, is the most common micro-organism isolated from LTX recipients. We aimed to see the outcomes of patients with bronchiectasis other than CF after LTX and seek the risk factors associated with pre- and post-transplant Pseudomonas status.

METHODS: Patients who underwent LTX at Tohoku University Hospital between January 2000 and December 2020 were consecutively included into the retrospective cohort study. Pre- and post-transplant prevalence of Pseudomonas colonization between bronchiectasis and other diseases was reviewed. Post-transplant outcomes (mortality and the development of chronic lung allograft dysfunction (CLAD)) were assessed using a Cox proportional hazards and time-to-event outcomes were estimated using the Kaplan-Meier method.

RESULTS: LTX recipients with bronchiectasis experienced a high rate of pre- and post-transplant Pseudomonas colonization compared to other diseases with statistical significance (p < 0.001 and p < 0.001, respectively). Nevertheless, long-term survival in bronchiectasis was as great as non-bronchiectasis (Log-rank p = 0.522), and the bronchiectasis was not a trigger for death (HR 1.62, 95% CI 0.63-4.19). On the other hand, the chance of CLAD onset in bronchiectasis was comparable to non-bronchiectasis (Log-rank p = 0.221), and bronchiectasis was not a predictor of the development of CLAD (HR 1.88, 95% CI 0.65-5.40).

CONCLUSIONS: Despite high prevalence of pre- and post-transplant Pseudomonas colonization, the outcome in LTX recipients with bronchiectasis other than CF was comparable to those without bronchiectasis.

PMID:34384425 | DOI:10.1186/s12890-021-01634-z

Future Microbiol. 2021 Aug 13. doi: 10.2217/fmb-2021-0150. Online ahead of print.

ABSTRACT

People with cystic fibrosis (CF) are highly susceptible to bacterial infections of the airways. By adulthood, chronic Pseudomonas aeruginosa (Pa) is the most prevalent infective organism and is difficult to eradicate owing to its adaptation to the CF lung microenvironment. Long-term suppressive treatment with inhaled antimicrobials is the standard care for reducing exacerbation frequency, improving quality of life and increasing measures of lung function. Levofloxacin (a fluoroquinolone antimicrobial) has been approved as an inhaled solution in Europe and Canada, for the treatment of adults with CF with chronic P. aeruginosa pulmonary infections. Here, we review the clinical principles relating to the use of inhaled antimicrobials and inhaled levofloxacin for the management of P. aeruginosa infections in patients with CF.

PMID:34384254 | DOI:10.2217/fmb-2021-0150

FASEB J. 2021 Sep;35(9):e21797. doi: 10.1096/fj.202100495R.

ABSTRACT

Pseudomonas aeruginosa is a frequent cause of hospital-acquired lung infections characterized by hyperinflammation, antibiotic resistance, and high morbidity/mortality. Here, we show that the genetic ablation of one cAMP-phosphodiesterase 4 subtype, PDE4B, is sufficient to protect mice from acute lung injury induced by P aeruginosa infection as it reduces pulmonary and systemic levels of pro-inflammatory cytokines, as well as pulmonary vascular leakage and mortality. Surprisingly, despite dampening immune responses, bacterial clearance in the lungs of PDE4B-KO mice is significantly improved compared to WT controls. In wildtypes, P aeruginosa-infection produces high systemic levels of several cytokines, including TNF-α, IL-1β, and IL-6, that act as cryogens and render the animals hypothermic. This, in turn, diminishes their ability to clear the bacteria. Ablation of PDE4B curbs both the initial production of acute response cytokines, including TNF-α and IL-1β, as well as their downstream signaling, specifically the induction of the secondary-response cytokine IL-6. This synergistic action protects PDE4B-KO mice from the deleterious effects of the P aeruginosa-induced cytostorm, while concurrently improving bacterial clearance, rather than being immunosuppressive. These benefits of PDE4B ablation are in contrast to the effects resulting from treatment with PAN-PDE4 inhibitors, which have been shown to increase bacterial burden and dissemination. Thus, PDE4B represents a promising therapeutic target in settings of P aeruginosa lung infections.

PMID:34383981 | DOI:10.1096/fj.202100495R

Clin Lab. 2021 Aug 1;67(8). doi: 10.7754/Clin.Lab.2021.210536.

ABSTRACT

BACKGROUND: Pseudomonas aeruginosa is a Gram-negative bacteria that causes a large range of human infections such as lung infection (cystic fibrosis) and urinary tract infection. Even worse, antibiotic resistant bacteria have become a serious health care problem throughout the last decade, and there is a need for a clear approach to regulate and prevent the spread of pseudomonas aeruginosa resistance.

METHODS: A complete analysis of Pseudomonas aeruginosa proteomics data showed that 25% of proteins are hypothetical proteins (HPs) whose function is not precisely defined. HP gene sequence analysis offers a framework for defining sequence-function relationships with a deeper understanding of organisms' molecular mechanisms at the system level. In the current research, we used the power of different bioinformatics tools to assign the potential roles for the HPs based on protein family association, amino acid function, motifs, and pathway analysis.

RESULTS: The current findings show that 30 HPs have well-defined functions and are classified as enzymes, DNA binding, periplasmic binding protein, transport, etc. Seven HPs showed virulence characteristics that is to be expected to be essential for Pseudomonas aeruginosa and pathogenesis survival.

CONCLUSIONS: This study's findings may encourage a better understanding of virulence mechanisms, drug resistance, pathogenesis, and drug discovery to treat Pseudomonas aeruginosa infections.

PMID:34383409 | DOI:10.7754/Clin.Lab.2021.210536

Autophagy. 2021 Aug 12:1-16. doi: 10.1080/15548627.2021.1956105. Online ahead of print.

ABSTRACT

Until recently, the ubiquitin-proteasome system (UPS) and macroautophagy/autophagy were considered to be two independent systems that target proteins for degradation by proteasomes or via lysosomes, respectively. Here, we report that TRIM44 (tripartite motif containing 44) is a novel link that connects the UPS system with the autophagy degradation pathway. Suppressing the UPS degradation pathway leads to TRIM44 upregulation, which further promotes aggregated protein clearance through the binding of K48 ubiquitin chains on proteins. TRIM44 expression activates autophagy via promoting SQSTM1/p62 oligomerization, which rapidly increases the rate of aggregate protein removal. Overall, our data reveal that TRIM44 is a newly identified link between the UPS system and the autophagy pathway. Delineating the cross-talk between these two degradation pathways may reveal new mechanisms of targeting aggregate-prone diseases, such as cancer and neurodegenerative disease.Abbreviations: 3-MA: 3-methyladenine; ACTB: actin beta; ATG5: autophagy related 5; BB: B-box domain; BECN1: beclin1; BM: bone marrow; CC: coiled-coil domain; CFTR: cystic fibrosis transmembrane conductance regulator; CON: control; CQ: chloroquine; DOX: doxycycline; DSP: dithiobis(succinimidly propionate); ER: endoplasmic reticulum; FI: fluorescence intensity; FL: full length; HIF1A/HIF-1#x3B1;: hypoxia inducible factor 1 subunit alpha; HSC: hematopoietic stem cells; HTT: huntingtin; KD: knockdown; KD-CON: knockdown construct control; MM: multiple myeloma; MTOR: mechanistic target of rapamycin kinase; NP-40: nonidet P-40; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; OE: overexpression; OE-CON: overexpression construct control; PARP: poly (ADP-ribose) polymerase; SDS: sodium dodecyl sulfate; SQSTM1/p62: sequestosome 1; Tet-on: tetracycline; TRIM44: tripartite motif containing 44; UPS: ubiquitin-proteasome system; ZF: zinc-finger.

PMID:34382902 | DOI:10.1080/15548627.2021.1956105

Physiol Rep. 2021 Aug;9(15):e14928. doi: 10.14814/phy2.14928.

ABSTRACT

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel whose dysfunction causes cystic fibrosis (CF). The loss of CFTR function in pulmonary epithelial cells causes surface dehydration, mucus build-up, inflammation, and bacterial infections that lead to lung failure. Little has been done to evaluate the effects of lipid perturbation on CFTR activity, despite CFTR residing in the plasma membrane. This work focuses on the acute effects of sphingomyelinase (SMase), a bacterial virulence factor secreted by CF relevant airway bacteria which degrades sphingomyelin into ceramide and phosphocholine, on the electrical circuitry of pulmonary epithelial monolayers. We report that basolateral SMase decreases CFTR-mediated transepithelial anion secretion in both primary bronchial and tracheal epithelial cells from explant tissue, with current CFTR modulators unable to rescue this effect. Focusing on primary cells, we took a holistic ion homeostasis approach to determine a cause for reduced anion secretion following SMase treatment. Using impedance analysis, we determined that basolateral SMase inhibits apical and basolateral conductance in non-CF primary cells without affecting paracellular permeability. In CF primary airway cells, correction with clinically relevant CFTR modulators did not prevent SMase-mediated inhibition of CFTR currents. Furthermore, SMase was found to inhibit only apical conductance in these cells. Future work should determine the mechanism for SMase-mediated inhibition of CFTR currents, and further explore the clinical relevance of SMase and sphingolipid imbalances.

PMID:34382377 | DOI:10.14814/phy2.14928

BJR Open. 2021 Jul 29;3(1):20210026. doi: 10.1259/bjro.20210026. eCollection 2021.

ABSTRACT

Non-cystic fibrosis bronchiectasis represents a heterogenous spectrum of disorders characterised by an abnormal and permanent dilatation of the bronchial tree associated with respiratory symptoms. To date, diagnosis relies on computed tomography (CT) evidence of dilated airways. Nevertheless, definite radiological criteria and standardised CT protocols are still to be defined. Although largely used, current radiological scoring systems have shown substantial drawbacks, mostly failing to correlate morphological abnormalities with clinical and prognostic data. In limited cases, bronchiectasis morphology and distribution, along with associated CT features, enable radiologists to confidently suggest an underlying cause. Quantitative imaging analyses have shown a potential to overcome the limitations of the current radiological criteria, but their application is still limited to a research setting. In the present review, we discuss the role of imaging and its current limitations in non-cystic fibrosis bronchiectasis. The potential of automatic quantitative approaches and artificial intelligence in such a context will be also mentioned.

PMID:34381953 | PMC:PMC8328081 | DOI:10.1259/bjro.20210026

Respir Med Case Rep. 2021 Jul 27;34:101487. doi: 10.1016/j.rmcr.2021.101487. eCollection 2021.

ABSTRACT

Inquilinus limosus is an uncommon, poorly understood bacterium capable of infecting the respiratory tracts of people with cystic fibrosis. The transmission, clinical relevance and changes in antimicrobial resistance of I. limosus over time are unclear due to the low frequency of identification. We report three co-habiting brothers with cystic fibrosis who developed chronic I. limosus infection and document the clinical and microbiological features of the infections. Clinical evolution after Inquilinus infection varied but was associated with an initial decline in lung function. Familial clustering of this rare pathogen raises the possibility of cross-infection as a potential mechanism of transmission of Inquilinus between CF patients.

PMID:34381683 | PMC:PMC8339227 | DOI:10.1016/j.rmcr.2021.101487

J Cyst Fibros. 2021 Aug 8:S1569-1993(21)01328-X. doi: 10.1016/j.jcf.2021.07.014. Online ahead of print.

ABSTRACT

BACKGROUND: There is conflicting evidence on the impact of liver disease (CFLD) on life expectancy in CF. Therefore the aim of this systematic review was to evaluate the impact of liver disease (CFLD) on mortality in CF.

METHODS: The protocol was published at (https://hrbopenresearch.org/articles/3-44/v3) using PRISPMA-P guidelines and registered in Prospero 2020 (CRD42020182885). Three databases were searched for publications (1938-2020) where the outcome was all-cause mortality (defined as death and transplantation) or CF-specific mortality in participants with CFLD. Studies with and without a comparator group were included. Studies were divided into 2 groups based on the definition of CFLD: Group 1 used 2 categories of liver disease (i) liver disease with portal hypertension (PH) (ii) non-specific abnormalities which did not meet the criteria for PH, Group 2 studies only included participants with PH.

RESULTS: All 14 eligible studies were observational, with a moderate-high risk of bias, Six of the 14 studies directly compared mortality between those with CFLD and those with no liver disease, and 5/6 demonstrated that those with CFLD had at least 3 time the risk of death compared to those with no liver disease. Pulmonary complications were the primary cause of death.

CONCLUSION: This SR demonstrates that liver disease shortens life expectancy in CF, and that pulmonary complications are the primary cause of death in those with CFLD. There has been no improvement in survival for persons with CFLD despite significant improvements in life expectancy for persons with CF who have no evidence of liver disease.

PMID:34380590 | DOI:10.1016/j.jcf.2021.07.014

Am J Respir Crit Care Med. 2021 Aug 11. doi: 10.1164/rccm.202101-0090LE. Online ahead of print.

NO ABSTRACT

PMID:34379998 | DOI:10.1164/rccm.202101-0090LE

Am J Transplant. 2021 Aug 11. doi: 10.1111/ajt.16791. Online ahead of print.

ABSTRACT

Nutritional status is known to strongly predict health outcomes in people with cystic fibrosis (CF), but the prevalence of and consequences for CF children with growth failure and underweight CF adults on the liver transplant (LT) waitlist has not been delineated. We utilized UNOS registry data from 2003-2017 to investigate the impact of growth failure and underweight on outcomes in liver transplant candidates with CF. Almost 1 in 3 children and adults with CF had growth failure or were underweight, respectively, at listing. Body mass index under-estimated growth failure compared to height and weight z-scores for children. In multivariate analysis of children, growth failure (HR 2.1, 95% CI 1.7-2.6) and CF (HR 2.7, 95% CI 1.6-4.6, vs Non-CF) were independent risk factors for waitlist death among children; having both increased death risk almost 4-fold (SHR 3.88, 95% CI 1.42-10.58). However, among children who did receive a LT, CF was not associated with death within 1-year post-LT. Underweight adult CF candidates were less likely to receive LT, again suggesting the importance of nutritional evaluation and early intervention in this at-risk cohort.

PMID:34379865 | DOI:10.1111/ajt.16791

J Antimicrob Chemother. 2021 Aug 11:dkab288. doi: 10.1093/jac/dkab288. Online ahead of print.

ABSTRACT

INTRODUCTION: Further optimization of therapeutic drug monitoring (TDM) for aminoglycosides (AGs) is urgently needed, especially in special populations such as those with cystic fibrosis (CF), >50% of whom develop ototoxicity if treated with multiple courses of IV AGs. This study aimed to empirically test a pharmacokinetic (PK) model using Bayesian estimation of drug exposure in the deeper body tissues to determine feasibility for prediction of ototoxicity.

MATERIALS AND METHODS: IV doses (n = 3645) of tobramycin and vancomycin were documented with precise timing from 38 patients with CF (aged 8-21 years), including total doses given and total exposure (cumulative AUC). Concentration results were obtained at 3 and 10 h for the central (C1) compartment. These variables were used in Bayesian estimation to predict trough levels in the secondary tissue compartments (C2 trough) and maximum concentrations (C2max). The C1 and C2 measures were then correlated with hearing levels in the extended high-frequency range.

RESULTS: Patients with more severe hearing loss were older and had a higher number of tobramycin C2max concentrations >2 mg/L than patients with normal or lesser degrees of hearing loss. These two factors together significantly predicted average high-frequency hearing level (r = 0.618, P < 0.001). Traditional metrics such as C1 trough concentrations were not predictive. The relative risk for hearing loss was 5.8 times greater with six or more tobramycin courses that exceeded C2max concentrations of 3 mg/L or higher, with sensitivity of 83% and specificity of 86%.

CONCLUSIONS: Advanced PK model-informed analysis predicted ototoxicity risk in patients with CF treated with tobramycin and demonstrated high test prediction.

PMID:34379758 | DOI:10.1093/jac/dkab288

Infect Dis Ther. 2021 Aug 11. doi: 10.1007/s40121-021-00507-6. Online ahead of print.

ABSTRACT

INTRODUCTION: A systematic literature review was undertaken to evaluate real-world use of ceftazidime-avibactam for infections due to aerobic Gram-negative organisms in adults with limited treatment options.

METHODS: Literature searches retrieved peer-reviewed publications and abstracts from major international infectious disease congresses from January 2015 to February 2021. Results were screened using pre-defined criteria to limit the dataset to relevant publications (notable exclusions were paediatric data and outcomes data for bacteria intrinsically resistant to ceftazidime-avibactam). Data for included publications were subjected to qualitative synthesis.

RESULTS: Seventy-three relevant publications (62 peer-reviewed articles; 10 abstracts) comprising 1926 patients treated with ceftazidime-avibactam (either alone or combined with other antimicrobials) and 1114 comparator/control patients were identified. All patients were hospitalised for serious illness and most had multiple comorbidities. The most common infections were pneumonia, bacteraemia, and skin/soft tissue, urinary tract, or abdominal infections; smaller numbers of patients with meningitis, febrile neutropenia, osteomyelitis, and cystic fibrosis were also included. Carbapenem-resistant or carbapenemase-producing Enterobacterales (CRE; n = 1718) and carbapenem-resistant, multidrug-resistant (MDR), and extensively drug-resistant Pseudomonas aeruginosa (n = 150) were the most common pathogens. Most publications reported positive outcomes for ceftazidime-avibactam treatment (clinical success rates ranged from 45 to 100% and reported 30-day mortality from 0 to 63%), which were statistically superior versus comparators in some studies. ceftazidime-avibactam resistance emergence occurred infrequently and mostly in Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae strains.

CONCLUSION: This review provides qualitative evidence of successful use of ceftazidime-avibactam for the treatment of hospitalised patients with CRE and MDR P. aeruginosa infections with limited treatment options.

PMID:34379310 | DOI:10.1007/s40121-021-00507-6

Qatar Med J. 2021 Jul 26;2021(1):24. doi: 10.5339/qmj.2021.24. eCollection 2021.

ABSTRACT

We report two cases of Qatari children with cystic fibrosis (CF) from different families presenting the homozygous CFTR 1521_1523delCTT (p. Phe508del) mutation with classic CF phenotypes. This gene mutation is considered the second CF mutation identified in Qatar. Herein, we review the frequency and distribution of this mutation in Arab countries.

PMID:34377682 | PMC:PMC8314207 | DOI:10.5339/qmj.2021.24

Respirol Case Rep. 2021 Aug 4;9(9):e0822. doi: 10.1002/rcr2.822. eCollection 2021 Sep.

ABSTRACT

Posaconazole is a triazole antifungal with a broad spectrum of activity against moulds including Aspergillus spp. Emerging data suggest posaconazole may be effective in the treatment of allergic bronchopulmonary aspergillosis (ABPA) complicating cystic fibrosis (CF). Rarely, posaconazole can cause pseudohyperaldosteronism, manifesting as hypertension and electrolyte abnormalities, with a number of cases recently reported in individuals without CF. We describe two cases of children with CF who developed hypertension, likely due to pseudohyperaldosteronism, following the initiation of posaconazole for the treatment of ABPA.

PMID:34377495 | PMC:PMC8334806 | DOI:10.1002/rcr2.822

Sci Immunol. 2021 Aug 10;6(62):eabg5021. doi: 10.1126/sciimmunol.abg5021.

ABSTRACT

To understand how a protective immune response against SARS-CoV-2 develops over time, we integrated phenotypic, transcriptional and repertoire analyses on PBMCs from mild and severe COVID-19 patients during and after infection, and compared them to healthy donors (HD). A type I IFN-response signature marked all the immune populations from severe patients during the infection. Humoral immunity was dominated by IgG production primarily against the RBD and N proteins, with neutralizing antibody titers increasing post infection and with disease severity. Memory B cells, including an atypical FCRL5+ T-BET+ memory subset, increased during the infection, especially in patients with mild disease. A significant reduction of effector memory, CD8+ T cells frequency characterized patients with severe disease. Despite such impairment, we observed robust clonal expansion of CD8+ T lymphocytes, while CD4+ T cells were less expanded and skewed toward TCM and TH2-like phenotypes. MAIT cells were also expanded, but only in patients with mild disease. Terminally differentiated CD8+ GZMB+ effector cells were clonally expanded both during the infection and post-infection, while CD8+ GZMK+ lymphocytes were more expanded post-infection and represented bona fide memory precursor effector cells. TCR repertoire analysis revealed that only highly proliferating T cell clonotypes, which included SARS-CoV-2-specific cells, were maintained post-infection and shared between the CD8+ GZMB+ and GZMK+ subsets. Overall, this study describes the development of immunity against SARS-CoV-2 and identifies an effector CD8+ T cell population with memory precursor-like features.

PMID:34376481 | DOI:10.1126/sciimmunol.abg5021

J Control Release. 2021 Aug 7:S0168-3659(21)00416-8. doi: 10.1016/j.jconrel.2021.08.010. Online ahead of print.

ABSTRACT

Nuclear factor κB (NFκB) is a unique protein complex that plays a major role in lung inflammation and respiratory dysfunction. The NFκB signaling pathway, therefore becomes an avenue for the development of potential pharmacological interventions, especially in situations where chronic inflammation is often constitutively active and plays a key role in the pathogenesis and progression of the disease. NFκB decoy oligodeoxynucleotides (ODNs) are double-stranded and carry NFκB binding sequences. They prevent the formation of NFκB-mediated inflammatory cytokines and thus have been employed in the treatment of a variety of chronic inflammatory diseases. However, the systemic administration of naked decoy ODNs restricts their therapeutic effectiveness because of their poor pharmacokinetic profile, instability, degradation by cellular enzymes and their low cellular uptake. Both structural modification and nanotechnology have shown promising results in enhancing the pharmacokinetic profiles of potent therapeutic substances and have also shown great potential in the treatment of respiratory diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. In this review, we examine the contribution of NFκB activation in respiratory diseases and recent advancements in the therapeutic use of decoy ODNs. In addition, we also highlight the limitations and challenges in use of decoy ODNs as therapeutic molecules, cellular uptake of decoy ODNs, and the current need for novel delivery systems to provide efficient delivery of decoy ODNs. Furthermore, this review provides a common platform for discussion on the existence of decoy ODNs, as well as outlining perspectives on the latest generation of delivery systems that encapsulate decoy ODNs and target NFκB in respiratory diseases.

PMID:34375688 | DOI:10.1016/j.jconrel.2021.08.010

Cell Discov. 2020 Aug 10;6(1):55. doi: 10.1038/s41421-020-00193-7.

ABSTRACT

The human SLC26 transporter family exhibits various transport characteristics, and family member SLC26A9 performs multiple roles, including acting as Cl-/HCO3- exchangers, Cl- channels, and Na+ transporters. Some mutations of SLC26A9 are correlated with abnormalities in respiration and digestion systems. As a potential target colocalizing with CFTR in cystic fibrosis patients, SLC26A9 is of great value in drug development. Here, we present a cryo-EM structure of the human SLC26A9 dimer at 2.6 Å resolution. A segment at the C-terminal end is bound to the entry of the intracellular vestibule of the putative transport pathway, which has been proven by electrophysiological experiments to be a gating modulator. Multiple chloride and sodium ions are resolved in the high-resolution structure, identifying novel ion-binding pockets for the first time. Together, our structure takes important steps in elucidating the structural features and regulatory mechanism of SLC26A9, with potential significance in the treatment of cystic fibrosis.

PMID:34373450 | DOI:10.1038/s41421-020-00193-7

Life Sci Alliance. 2021 Aug 9;4(10):e202000940. doi: 10.26508/lsa.202000940. Print 2021 Oct.

ABSTRACT

Prime editing is a recently reported genome editing tool using a nickase-cas9 fused to a reverse transcriptase that directly synthesizes the desired edit at the target site. Here, we explore the use of prime editing in human organoids. Common TP53 mutations can be correctly modeled in human adult stem cell-derived colonic organoids with efficiencies up to 25% and up to 97% in hepatocyte organoids. Next, we functionally repaired the cystic fibrosis CFTR-F508del mutation and compared prime editing to CRISPR/Cas9-mediated homology-directed repair and adenine base editing on the CFTR-R785* mutation. Whole-genome sequencing of prime editing-repaired organoids revealed no detectable off-target effects. Despite encountering varying editing efficiencies and undesired mutations at the target site, these results underline the broad applicability of prime editing for modeling oncogenic mutations and showcase the potential clinical application of this technique, pending further optimization.

PMID:34373320 | DOI:10.26508/lsa.202000940

mBio. 2021 Aug 10:e0086021. doi: 10.1128/mBio.00860-21. Online ahead of print.

ABSTRACT

Bacteria live in spatially organized aggregates during chronic infections, where they adapt to the host environment, evade immune responses, and resist therapeutic interventions. Although it is known that environmental factors such as polymers influence bacterial aggregation, it is not clear how bacterial adaptation during chronic infection impacts the formation and spatial organization of aggregates in the presence of polymers. Here, we show that in an in vitro model of cystic fibrosis (CF) containing the polymers extracellular DNA (eDNA) and mucin, O-specific antigen is a major factor determining the formation of two distinct aggregate assembly types of Pseudomonas aeruginosa due to alterations in cell surface hydrophobicity. Our findings suggest that during chronic infection, the interplay between cell surface properties and polymers in the environment may influence the formation and structure of bacterial aggregates, which would shed new light on the fitness costs and benefits of O-antigen production in environments such as CF lungs. IMPORTANCE During chronic infection, several factors contribute to the biogeography of microbial communities. Heterogeneous populations of Pseudomonas aeruginosa form aggregates in cystic fibrosis airways; however, the impact of this population heterogeneity on spatial organization and aggregate assembly is not well understood. In this study, we found that changes in O-specific antigen determine the spatial organization of P. aeruginosa cells by altering the relative cell surface hydrophobicity. This finding suggests a role for O-antigen in regulating P. aeruginosa aggregate size and shape in cystic fibrosis airways.

PMID:34372703 | DOI:10.1128/mBio.00860-21