Br J Clin Pharmacol. 2025 Apr 2. doi: 10.1002/bcp.70027. Online ahead of print.

ABSTRACT

AIM: Dipeptidyl peptidase-1 (DPP-1) inhibitors have been studied for the treatment of neutrophil-mediated inflammatory diseases including bronchiectasis, bronchial asthma and cystic fibrosis. This study evaluated the pharmacokinetics, pharmacodynamics, safety and tolerability of DPP-1 inhibitor HSK31858 in healthy Chinese volunteers.

METHODS: Volunteers in Part A randomly received single doses of HSK31858 (15, 40, 60 and 80 mg) or placebo in fasted states. The 40-mg cohort also received HSK31858 40 mg or placebo in fed states. In Part B, volunteers randomly received HSK31858 10, 20 and 40 mg or placebo once daily for 28 days in fasted states. The primary endpoints were safety and tolerability of HSK31858.

RESULTS: Among 38 volunteers in Part A and 36 in Part B, HSK31858 was well tolerated; no deaths, serious adverse events, or discontinuations due to adverse events occurred. The median Tmax was 0.75 to 1.0 h and the mean terminal t1/2 was 16.5 to 21.0 h in the fasted state with single doses of HSK31858. Both Cmax and AUC0-t exhibited a dose-dependent rise. Food had no effect on AUC. Multiple doses of HSK31858 demonstrated a similar pharmacokinetics profile, with about 2-fold accumulation in AUC. HSK31858 dose-dependently inhibited neutrophil count-normalized neutrophil elastase (NEnorm) activity. The maximal percentage decrease in NEnorm activity relative to baseline during 28 days of HSK31858 treatments was 13.6% and 76.4% with HSK31858 10 and 40 mg once-daily, respectively.

CONCLUSION: HSK31858 was safe and well tolerated. The pharmacokinetics and pharmacodynamics profile of HSK31858 supports further clinical development for the treatment of neutrophil-mediated inflammatory diseases.

TRIAL REGISTRATION: NCT05663593.

PMID:40170587 | DOI:10.1002/bcp.70027

Ther Adv Respir Dis. 2025 Jan-Dec;19:17534666251329792. doi: 10.1177/17534666251329792. Epub 2025 Apr 1.

NO ABSTRACT

PMID:40170358 | DOI:10.1177/17534666251329792

Commun Biol. 2025 Apr 2;8(1):540. doi: 10.1038/s42003-025-07944-w.

ABSTRACT

Preterm birth disrupts intestinal epithelial maturation, impairing digestive and absorptive functions. This study integrates analysis of single-cell RNA sequencing datasets, spanning fetal to adult stages, with human preterm intestinal models derived from the ileal tissue of preterm infants. We investigate the potential of extracellular vesicles (EVs) derived from human Wharton's jelly mesenchymal stem cells to promote intestinal maturation. Distinct enterocyte differentiation trajectories are identified during the transition from immature to mature stages of human intestinal development. EV treatment, particularly with the EV39 line, significantly upregulates maturation-specific gene expression related to enterocyte function. Gene set enrichment analysis reveals an enrichment of TGFβ1 signaling pathways, and proteomic analysis identifies TGFβ1 and FGF2 as key mediators of EV39's effects. These treatments enhance cell proliferation, epithelial barrier integrity, and fatty acid uptake, primarily through CFTR-dependent mechanisms-unique to human preterm models, not observed in mouse intestinal organoids. This highlights the translational potential of EV39 and CFTR activation in promoting the functional maturation of the premature human intestine.

PMID:40169914 | DOI:10.1038/s42003-025-07944-w

Basic Clin Androl. 2025 Apr 1;35(1):13. doi: 10.1186/s12610-025-00260-7.

ABSTRACT

BACKGROUND: Azoospermia, the most severe form of male infertility, is categorized into two types: non-obstructive azoospermia (NOA) and obstructive azoospermia (OA), which exhibit significant genetic heterogeneity. Azoospermia factor (AZF) deletion is a common cause of NOA, whereas congenital bilateral absence of the vas deferens (CBAVD), a severe subtype of OA, is frequently linked to cystic fibrosis transmembrane conductance regulator (CFTR) gene variants. This case report is the first to document the coexistence of a partial AZFa microdeletion and a homozygous CFTR variant in a CBAVD-affected azoospermic patient with intact spermatogenesis.

CASE PRESENTATION: A 32-year-old man presented with primary infertility and azoospermia. Clinical evaluation revealed CBAVD (normal hormone levels, low semen volume, pH 6.0, and absence of the vas deferens). Genetic analysis accidentally revealed a 384.9 kb AZFa deletion (sY84 and sY86, but not sY1064, 1182) that removed USP9Y but retained DDX3Y in the proband, his fertile brother, and his father. A homozygous CFTR variant (TG12-5T) was also detected in the proband and his brother and was inherited from heterozygous parental carriers. Microdissection testicular sperm extraction (micro-TESE) revealed intact spermatogenesis, confirmed by histology and immunofluorescence, indicating normal germ cell development.

CONCLUSION: This case expands the intricate genetic spectrum of azoospermia by illustrating the critical role of DDX3Y in the AZFa region in spermatogenesis and the variable penetrance of CFTR variant (TG12-5T) in CBAVD. These insights may refine diagnostic strategies and underscore the necessity for tailored fertility management in individuals with multifactorial genetic anomalies.

PMID:40169970 | DOI:10.1186/s12610-025-00260-7

Biomed Pharmacother. 2025 Mar 31;186:117957. doi: 10.1016/j.biopha.2025.117957. Online ahead of print.

ABSTRACT

BACKGROUND: Overactive neutrophilic inflammation causes damage to the airways and death in people with cystic fibrosis (CF), a genetic disorder resulting from mutations in the CFTR gene. Reducing the impact of inflammation is therefore a major concern in CF. Evidence indicates that dysfunctional NRF2 signaling in CF individuals may impair their ability to regulate their oxidative and inflammatory responses, although the role of NRF2 in neutrophil-dominated inflammation and tissue damage associated with CF has not been determined. Therefore, we examined whether curcumin, an activator of NRF2, might provide a beneficial effect in the context of CF.

METHODS: Combining Cftr-depleted zebrafish as an innovative biomedical model with CF patient-derived airway organoids (AOs), we aimed to understand how NRF2 dysfunction leads to abnormal inflammatory status and tissue remodeling and determine the effects of curcumin in reducing inflammation and tissue damage in CF.

RESULTS: We demonstrate that NFR2 is instrumental in regulating neutrophilic inflammation and repair processes in vivo, thereby preventing inflammatory damage. Importantly, curcumin treatment restores NRF2 activity in both CF zebrafish and AOs. Curcumin reduces neutrophilic inflammation in CF context, by rebalancing the production of epithelial ROS and pro-inflammatory cytokines. Furthermore, curcumin improves tissue repair by reducing CF-associated fibrosis. Our findings demonstrate that curcumin prevents CF-mediated inflammation via activating the NRF2 pathway.

CONCLUSIONS: This work highlights the protective role of NRF2 in limiting inflammation and injury and show that therapeutic strategies to normalize NRF2 activity, using curcumin or others NRF2 activators, might simultaneously reduce airway inflammation and damage in CF.

PMID:40168724 | DOI:10.1016/j.biopha.2025.117957

PLoS Pathog. 2025 Apr 1;21(4):e1013017. doi: 10.1371/journal.ppat.1013017. Online ahead of print.

ABSTRACT

Anthrax lethal toxin (LT) and edema toxin (ET) are two of the major virulence factors of Bacillus anthracis, the causative pathogen of anthrax disease. While the roles of LT in anthrax pathogenesis have been extensively studied, the pathogenic mechanism of ET remains poorly understood. ET is a calmodulin-dependent adenylate cyclase that elevates intracellular cAMP by converting ATP to cAMP. Thus, it was postulated that the ET-induced in vivo toxicity is mediated by certain cAMP-dependent events. However, mechanisms linking cAMP elevation and ET-induced damage have not been established. Cholera toxin is another bacterial toxin that increases cAMP. This toxin is known to cause severe intestinal fluid secretion and dehydration by cAMP-mediated activation of protein kinase A (PKA), which in turn activates cystic fibrosis transmembrane conductance regulator (CFTR). The cAMP-activated PKA phosphorylation of CFTR on the surface of intestinal epithelial cells leads to an efflux of chloride ions accompanied by secretion of H2O into the intestinal lumen, causing rapid fluid loss, severe diarrhea and dehydration. Due to similar in vivo effects, it was generally believed that ET and cholera toxin would exhibit a similar pathogenic mechanism. Surprisingly, in this work, we found that cAMP-mediated PKA/CFTR activation is not essential for ET to exert its in vivo toxicity. Instead, our data suggest that ET-induced ATP depletion may play an important role in the toxin's pathogenesis.

PMID:40168442 | DOI:10.1371/journal.ppat.1013017

Pediatr Pulmonol. 2025 Apr;60(4):e71076. doi: 10.1002/ppul.71076.

ABSTRACT

BACKGROUND: The effects of CFTR modulators, particularly elexacaftor/tezacaftor/ivacaftor (ETI), on exercise capacity in people with cystic fibrosis (pwCF) remain unclear, with no data available on their impact within the context of an exercise intervention. Therefore, this study aimed to assess the effects of an exercise intervention on exercise capacity in adults with CF, comparing those treated with and without ETI.

METHODS: A total of 56 adult pwCF participated in this quasi-experimental study as part of a rehabilitation program, which included a 3.5-week exercise intervention. The program involved five weekly 45-min sessions, including endurance training on a cycle ergometer. VO2 peak and Wpeak were the primary outcomes used to assess changes in exercise capacity.

RESULTS: The intervention significantly increased VO2 peak and Wpeak in all pwCF, regardless of ETI use, with similar improvements between groups. PwCF with lower baseline fitness (VO2 peak ≤ 81%pred) showed greater improvements than those with higher fitness (VO2 peak ≥ 82%pred). ppFEV1 remained unchanged, while BMI increased in both groups. Notably, the ETI group spent significantly more time in physical activity (PA) at hard and very hard intensities compared to the non-ETI group. Additionally, a positive correlation was observed between PA intensity and VO2 peak and Wpeak in the ETI group.

CONCLUSION: Independent of ETI treatment, adult pwCF improve their exercise capacity by participating in a regular exercise program. ETI treatment appears to enhance time spent in higher PA intensities. Despite the effectiveness of CFTR modulators, regular PA and exercise remain essential to maintain and improve exercise capacity in pwCF.

PMID:40167900 | DOI:10.1002/ppul.71076

Disabil Rehabil. 2025 Apr 1:1-9. doi: 10.1080/09638288.2025.2484779. Online ahead of print.

ABSTRACT

Purpose: Adherence to airway clearance therapy (ACT) among individuals with cystic fibrosis (CF) is often inconsistent. This study aims to explore the perceptions of adults with CF regarding their experiences with ACT and what influences their selection of specific ACTs. Findings may help inform clinician approaches to patient care and ACT. Materials and Methods: A qualitative descriptive study was conducted using individual, semi-structured interviews. Eight participants [six male and two female, median (min-max) age 42.5 (27-52)] were purposively recruited from the Toronto Adult CF Centre at St. Michael's Hospital, Unity Health Toronto. Results: Four key themes were generated from participants' accounts. First, they described the intensive nature of CF self-management and its influence on their perceptions and selection of ACT techniques. Second, they emphasized the importance of healthcare professional guidance in treatment decisions. Third, physical health status, exercise, and CF transmembrane conductance regulator modulator therapy also shaped participants' self-management approaches. Lastly, their social context influenced how they navigated self-management, which evolved over time. Conclusion: This study shows that ACT technique selection is influenced by various evolving needs across the lifespan. Understanding the role that patient experiences play in ACT technique selection may help clinicians personalize recommendations and promote patient-centred care.

PMID:40167245 | DOI:10.1080/09638288.2025.2484779

Biopsychosoc Sci Med. 2025 Mar 24. doi: 10.1097/PSY.0000000000001387. Online ahead of print.

ABSTRACT

OBJECTIVE: An emerging body of evidence suggests that psychological flexibility may be an important and underexamined determinant of overall psychological functioning. The chronic nature of Cystic Fibrosis (CF) may require a greater level of flexibility to navigate complex and dynamic health concerns in an increasingly aging population.

METHODS: We examined associations between psychological flexibility, coping styles, psychological grit, and negative affectivity (anxiety and depressive symptoms) from baseline assessments of randomized trial among adults with CF. Regression models controlling for age, gender, income, psychotropic medication use and pulmonary function were used to characterize associations between psychological flexibility, coping styles and negative affect.

RESULTS: A total of 124 individuals were included in analyses, 74 (60%) of whom were taking a psychotropic medication. Depressive (BDI-II=18.6 [SD=9.9]) and anxious (BAI=13.8 [SD=9.3]) symptoms were both elevated. Greater levels of psychological flexibility were associated with lower negative affect, such that individuals reporting less cognitive fusion (B=-0.59, P<0.001) and greater psychological acceptance (B=-0.51. P<0.001) exhibited lesser levels of anxiety and depressive symptoms. Psychological flexibility was the most robust correlate of negative affect after accounting for other coping variables (B=-0.50, P<0.001) and this association was not moderated by FEV1/FVC levels.

CONCLUSIONS: Psychological flexibility is robustly associated with decreased negative affect among individuals with CF, independent of background and clinical characteristics.

PMID:40167140 | DOI:10.1097/PSY.0000000000001387

J Pediatr Gastroenterol Nutr. 2025 Mar 31. doi: 10.1002/jpn3.70029. Online ahead of print.

ABSTRACT

OBJECTIVES: We determined the prevalence of anemia and its characteristics in children with newly diagnosed inflammatory bowel disease (IBD) and investigated its trend during follow-up.

METHODS: An observational, multicenter cohort study of IBD children with anemia at the diagnosis enrolled in the Italian Society of Pediatric Gastroenterology, Hepatology, and Nutrition IBD registry. Data were collected at the diagnosis and at 1 year.

RESULTS: Five hundred eighty-nine (295 Crohn's disease [CD] [50%] and 294 ulcerative colitis [UC]/IBD unclassified [IBDU] [50%]) of 1634 patients with IBD presented with anemia (36%). Anemia rate was higher in CD than in UC (39% vs. 33%, p = 0.009), and most patients had moderate anemia (55%). Children with CD had higher rates of mild anemia than UC (38% vs. 33%, p < 0.0001), while severe anemia was more common in UC (13% vs. 6%, p = 0.001). In CD, lower age at the diagnosis and lower albumin level correlated with anemia severity (p = 0.0007 and <0.0001, respectively). In UC, severe disease was more common in patients with severe anemia compared to those with mild and moderate anemia (20.6% vs. 43.6%, p = 0.01; 17% vs. 43.6%, p = 0.001). At 1 year, 99 children (22.9%) were persistently anemic and were characterized by a more severe disease compared to those who had resolved their anemia.

CONCLUSIONS: More than one third of IBD children present with anemia, most commonly moderate. Severe anemia is more common in UC compared to CD. One in four patients is still anemic after 1 year from the diagnosis, suggesting inadequate attention to the issue and the need for dedicated therapeutic management and careful monitoring.

PMID:40165528 | DOI:10.1002/jpn3.70029

Stat Methods Med Res. 2025 Mar 31:9622802251316971. doi: 10.1177/09622802251316971. Online ahead of print.

ABSTRACT

G-formula is a popular approach for estimating the effects of time-varying treatments or exposures from longitudinal data. G-formula is typically implemented using Monte-Carlo simulation, with non-parametric bootstrapping used for inference. In longitudinal data settings missing data are a common issue, which are often handled using multiple imputation, but it is unclear how G-formula and multiple imputation should be combined. We show how G-formula can be implemented using Bayesian multiple imputation methods for synthetic data, and that by doing so, we can impute missing data and simulate the counterfactuals of interest within a single coherent approach. We describe how this can be achieved using standard multiple imputation software and explore its performance using a simulation study and an application from cystic fibrosis.

PMID:40165440 | DOI:10.1177/09622802251316971

BMJ Open Respir Res. 2025 Mar 31;12(1):e002546. doi: 10.1136/bmjresp-2024-002546.

ABSTRACT

BACKGROUND: A person's beliefs about treatment influence their engagement and adherence to that treatment. The Necessity-Concerns Framework suggests that adherence is influenced by a person's judgement of their own need for treatment (necessity beliefs) and concerns about the potential adverse consequences of taking the treatment. This study was conducted to explore the Necessity-Concerns Framework for elexacaftor-tezacaftor-ivacaftor (ETI) therapy (Kaftrio) in adults with cystic fibrosis (CF).

METHODS: A total of 64 adults with CF were maintained on ETI therapy as part of their routine CF care, and completed the Beliefs about Medicines Questionnaire. Patient demographics, lung function, body mass index and quality of life using the Cystic Fibrosis Questionnaire Revised were collected as part of routine clinical care. Duration of ETI therapy along with medicines possession ratio was recorded.

RESULTS: Patients reported strong beliefs about the necessity of ETI therapy. The majority of patients (78%) reported low concerns about ETI therapy while 22% of patients reported high concerns. A small number of patients (n=4) had concerns which were stronger than their beliefs about necessity.

DISCUSSION: Patients reported strong beliefs in the necessity of ETI therapy. Although concerns were lower, a significant proportion of the sample had strong concerns about their ETI therapy. By being aware of people with CF's necessity and concerns beliefs around ETI therapy clinical teams will be better armed to engage them in treatment decisions and support optimal adherence.

PMID:40164471 | DOI:10.1136/bmjresp-2024-002546

Respir Physiol Neurobiol. 2025 Mar 29:104423. doi: 10.1016/j.resp.2025.104423. Online ahead of print.

ABSTRACT

Physical activity is a leading trigger of dyspnea in chronic cardiopulmonary diseases. Recently, there has been a renewed interest in uncovering the mechanisms underlying this distressing symptom. We start by articulating a conceptual framework linking cardiorespiratory abnormalities with the central perception of undesirable respiratory sensations during exercise. We specifically emphasize that exertional dyspnea ultimately reflects an imbalance between (high) demand and (low) capacity. As such, the symptom arises in the presence of a heightened inspiratory neural drive - the will to breathe - secondary to a) increased ventilatory output relative to the instantaneous ventilatory capacity (excessive breathing) and/or b) its impeded translation into the act of breathing due to constraints on tidal volume expansion (constrained breathing). In patients with chronic obstructive pulmonary disease (COPD), asthma, cystic fibrosis, and interstitial lung disease (ILD), constrained breathing assumes a more dominant role as the disease progresses. Excessive breathing due to heightened wasted ventilation in the physiological dead space is particularly important in the initial stages of COPD, while alveolar hyperventilation has a major contributory role in hypoxemic patients with ILD. Hyperventilation is also a leading driver of dyspnea in heart failure (HF) with reduced ejection fraction (EF), while high physiological dead space is the main underlying mechanism in HF with preserved EF. Similarly, wasted ventilation in poorly perfused lung tissue dominates the scene in pulmonary vascular disease. New artificial intelligence-based approaches to expose the contribution of excessive and constrained breathing may enhance the yield of cardiopulmonary exercise testing in investigating exertional dyspnea in these patients.

PMID:40164293 | DOI:10.1016/j.resp.2025.104423

Biochemistry (Mosc). 2025 Jan;90(Suppl 1):S214-S232. doi: 10.1134/S0006297924603496.

ABSTRACT

Mycobacterium abscessus is a non-tuberculosis fast-growing mycobacterium that has recently become a serious concern due to its rapidly increasing prevalence worldwide, mainly in individuals with a high susceptibility to pulmonary infections, for example, patients with cystic fibrosis, bronchiectasis, chronic obstructive pulmonary disease, and previous tuberculosis infection. According to present estimations, at least 20% of patients with cystic fibrosis are infected with M. abscessus. This bacterium is extremely resistant to most drugs, leading to a severe and difficult-to-treat infection. That is why M. abscessus, previously classified as a low-virulent opportunistic pathogen, is now reconsidered as a true pathogenic bacterium. There are no effective drugs for successful M. abscessus infection therapy, as well as no vaccines to prevent its spread. This review focuses on the molecular mechanisms ensuring M. abscessus resistance to immune response and its ability to survive in the aggressive intracellular environment of human immune cells, and describes virulence factors that can serve as potential targets for the development of innovative therapeutic approaches to combat the spread of infections caused by M. abscessus.

PMID:40164160 | DOI:10.1134/S0006297924603496

PLoS One. 2025 Mar 31;20(3):e0319710. doi: 10.1371/journal.pone.0319710. eCollection 2025.

ABSTRACT

Mycobacterium abscessus (MABS) is an emerging pathogen causing severe infections, particularly in cystic fibrosis (CF) patients. A prospective multicentre study included CF patients from four hospitals in Madrid between January 2022 and January 2024. Respiratory samples were collected, and MABS isolates were analysed to determine their antibiotic resistance profiles, growth dynamics, infection kinetics, intracellular behaviour, and pathogenicity. Intracellular bacterial growth and macrophage viability were evaluated through THP-1 cell infection experiments, with and without amikacin. Phenotypic susceptibility testing and genotypic susceptibility testing were also conducted. Among 148 patients, 28 MABS isolates were detected from 16 patients (10.8%), and the first isolate from each patient was analysed. Isolation was more prevalent in younger individuals (median age 24.4 vs. 28.4 years, p = 0.049), and most isolates (81.25%) were identified as M. abscessus subsp. abscessus (MABSa). MABS isolates exhibited high resistance rates (>85%) to doxycycline, tobramycin, ciprofloxacin, moxifloxacin (75%) and cotrimoxazole (56.3%). Amikacin resistance (18.8%) was higher than expected, and inducible (10/16 isolates) or acquired (1/16 isolate) macrolide resistance was found in 68.8% of strains. Phenotypic and genotypic testing results were fully concordant. Tigecycline demonstrated strong in vitro activity, and resistance to imipenem, linezolid, and cefoxitin remained low. Rough strains displayed lower optical density values in later growth stages, probably due to their increased aggregation. In THP-1 cell infection experiments, rough strains showed higher intracellular bacterial loads with statistically significant differences observed at 2 hours (both with and without amikacin) and at 72 hours (with amikacin) post infection. Notably, rough strains also exhibited a higher internalisation index and greater impact on THP-1 cell viability, especially in the absence of amikacin.

PMID:40163512 | DOI:10.1371/journal.pone.0319710

Ther Adv Respir Dis. 2025 Jan-Dec;19:17534666251323194. doi: 10.1177/17534666251323194. Epub 2025 Mar 31.

ABSTRACT

Over the past decade, major clinical advances have been made in the healthcare and therapeutic development for cystic fibrosis (CF), a lethal genetic disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein. CFTR modulators represent innovative treatments that directly target the primary defects in the mutated CFTR protein and have demonstrated significant clinical benefits for many people with CF (pwCF) who are eligible for these treatments. In particular, the triple combination therapy composed of elexacaftor, tezacaftor, and ivacaftor (ETI) has changed the CF therapeutic landscape by significantly improving lung function, quality of life, and predicted survival rates. Here, we provided a comprehensive summary of the impact of ETI on clinical outcomes and the need for further research on long-term efficacy, side effects, pregnancy, possible drug-drug interactions, and extra-pulmonary manifestations. Moreover, a significant number of pwCF are unresponsive to these drugs or cannot afford their high costs. We, therefore, discussed health inequity issues and alternative therapeutic strategies under development aiming to obtain effective therapies for all pwCF.

PMID:40163448 | DOI:10.1177/17534666251323194

Microbiol Spectr. 2025 Mar 31:e0214924. doi: 10.1128/spectrum.02149-24. Online ahead of print.

ABSTRACT

Pseudomonas aeruginosa is an opportunistic pathogen that can cause sinus infections and pneumonia in cystic fibrosis (CF) patients. Bacteriophage therapy is being investigated as a treatment for antibiotic-resistant P. aeruginosa infections. Although virulent bacteriophages have shown promise in treating P. aeruginosa infections, the development of bacteriophage-insensitive mutants (BIMs) in the presence of bacteriophages has been described. The aim of this study was to examine the genetic changes associated with the BIM phenotype. Biofilms of three genetically distinct P. aeruginosa strains, including PAO1 (ATCC 15692), and two clinical respiratory isolates (one CF and one non-CF) were grown for 7 days and treated with either a cocktail of four bacteriophages or a vehicle control for 7 consecutive days. BIMs isolated from the biofilms were detected by streak assays, and resistance to the phage cocktail was confirmed using spot test assays. Comparison of whole genome sequencing between the recovered BIMs and their respective vehicle control-treated phage-sensitive isolates revealed structural variants in two strains, and several small variants in all three strains. These variations involved a TonB-dependent outer membrane receptor in one strain, and mutations in lipopolysaccharide synthesis genes in two strains. Prophage deletion and induction were also noted in two strains, as well as mutations in several genes associated with virulence factors. Mutations in genes involved in susceptibility to conventional antibiotics were also identified in BIMs, with both decreased and increased antibiotic sensitivity to various antibiotics being observed. These findings may have implications for future applications of lytic phage therapy.IMPORTANCELytic bacteriophages are viruses that infect and kill bacteria and can be used to treat difficult-to-treat bacterial infections, including biofilm-associated infections and multidrug-resistant bacteria. Pseudomonas aeruginosa is a bacterium that can cause life-threatening infections. Lytic bacteriophage therapy has been trialed in the treatment of P. aeruginosa infections; however, sometimes bacteria develop resistance to the bacteriophages. This study sheds light on the genetic mechanisms of such resistance, and how this might be harnessed to restore the sensitivity of multidrug-resistant P. aeruginosa to conventional antibiotics.

PMID:40162801 | DOI:10.1128/spectrum.02149-24

bioRxiv [Preprint]. 2025 Mar 12:2025.03.12.642861. doi: 10.1101/2025.03.12.642861.

ABSTRACT

Pseudomonas aeruginosa and Staphylococcus aureus are primary bacterial pathogens isolated from the airways of cystic fibrosis patients. P. aeruginosa produces secondary metabolites that negatively impact the fitness of S. aureus, allowing P. aeruginosa to become the most prominent bacterium when the species are co-cultured. Some of these metabolites inhibit S. aureus respiration. SrrAB is a staphylococcal two-component regulatory system (TCRS) that responds to alterations in respiratory status and helps S. aureus transition between fermentative and respiratory metabolisms. We used P. aeruginosa mutant strains and chemical genetics to demonstrate that P. aeruginosa secondary metabolites, HQNO in particular, inhibit S. aureus respiration, resulting in modified SrrAB stimulation. Metabolomic analyses found that the ratio of NAD + to NADH increased upon prolonged culture with HQNO. Consistent with this, the activity of the Rex transcriptional regulator, which senses and responds to alterations in the NAD + / NADH ratio, had altered activity upon HQNO treatment. The presence of SrrAB increased fitness when cultured with HQNO and increased survival when challenged with P. aeruginosa. S. aureus strains with a decreased ability to maintain redox homeostasis via fermentation had decreased fitness when challenged with HQNO and decreased survival when challenged with P. aeruginosa . These findings led to a model wherein P. aeruginosa secreted HQNO inhibits S. aureus respiration, stimulating SrrAB, which promotes fitness and survival by increasing carbon flux through fermentative pathways to maintain redox homeostasis.

IMPORTANCE: Cystic fibrosis (CF) is a hereditary respiratory disease that predisposes patients to bacterial infections, primarily caused by Staphylococcus aureus and Pseudomonas aeruginosa . P. aeruginosa excreted secondary metabolites decrease S. aureus fitness during co-infection, ultimately eliminating it. The genetic mechanisms that S. aureus uses to detect and respond to these metabolites are unknown. The S. aureus SrrAB two-component regulatory system senses flux through respiratory pathways and increases transcription of genes utilized for adaption to low-respiration environments. This study demonstrates that SrrAB responds to the P. aeruginosa -produced respiratory toxin HQNO and responds by increasing fermentation increasing competition. This study describes interactions between these two bacterial pathogens, which could be exploited to decrease pathogen burden in individuals living with cystic fibrosis.

PMID:40161799 | PMC:PMC11952440 | DOI:10.1101/2025.03.12.642861

bioRxiv [Preprint]. 2025 Mar 13:2025.03.11.642711. doi: 10.1101/2025.03.11.642711.

ABSTRACT

Drug delivery platforms, complex lipid nanoparticles (LNPs) and extracellular vesicles (EVs) have both faced a number of key challenges ranging from organ specificity to loading capacity and stability. A key challenge in EV biology as well as LNP design remains vesicle to cell interaction and the creation of a polar permeability pathway necessary for cargo exchange. Membrane to membrane recognition and intercalation are tantamount to delivery and integral to function of both EVs and LNPs, both complex and single component. We reasoned that the overlapping advantages of both nanoparticles centered on compositional lipids. EVs are encapsulations using biological membrane lipids and expressed proteins and have a larger carrier capacity. LNPs are composed of synthetic lipids differing in charge and amount mimicking those present in biological membranes and include a synthetic lipid of choice that carries a charge, designed to enhance biological membrane disruption and subsequent cargo off-loading. Our goal was to design hybrid EVs (HEVs) that combined both elements. We manufactured positively charged liposomes (Lip) carrying mRNA coding for fluorescent proteins to load isolated EVs in order to create a combinatorial delivery platform. Using knowledge from LNP-based mRNA vaccine delivery, we have formulated and characterized HEVs. Future therapeutic strategies could involve isolating EVs from patients, hybridizing them with synthetic lipids loaded with desired payloads, and reintroducing them to the patient. This approach is particularly relevant for enhancing the function of pulmonary innate immunity in diseases like cystic fibrosis, chronic granulomatous disease, and pulmonary fibrosis. By conducting both in-vitro and in-vivo assays, we demonstrate that HEVs exhibit comparable transfection efficacy to LNPs composed of complex synthetic lipids, while significantly reducing cytotoxicity. This highlights their potential as safer and more efficient delivery vehicles.

PMID:40161690 | PMC:PMC11952422 | DOI:10.1101/2025.03.11.642711

Respiration. 2025 Mar 28:1-10. doi: 10.1159/000545552. Online ahead of print.

ABSTRACT

INTRODUCTION: Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene. A minority of people with CF carry two heterozygous CFTR mutations other than the common Phe508del, complicating diagnosis and treatment.

CASE PRESENTATION: We report the case of a 25-year-old South American male diagnosed with CF respiratory disease, characterized by a history of recurrent infections, pulmonary Mycobacterium abscessus infection, airway disease on high-resolution CT, and an elevated sweat chloride level (74 mmol/L). Exome sequencing identified a unique combination of CFTR mutations: a pathogenic frameshift variant (c.2052dup) and a variant of unknown clinical significance (c.710A>C). Notably, there were no signs of pancreatic insufficiency. Rectal mucosal organoid cultures demonstrated residual CFTR function with responsiveness to ivacaftor and the combination of elexacaftor, tezacaftor, and ivacaftor.

CONCLUSION: This case highlights a unique combination of heterozygous CFTR variants in a person with late-onset CF respiratory disease, which may be amenable to CFTR modulation therapy.

PMID:40159410 | DOI:10.1159/000545552