Journal of Cystic Fibrosis最新文献

The Cystic Fibrosis Transmembrane conductance Regulator (CFTR) modulator VX-445 (Elexacaftor) used to treat cystic fibrosis presents both corrector and potentiator activities. This drug binds to a pocket within the CFTR membrane-spanning domain (MSD) assembly, in contact with the lasso motif. We have previously shown that the corrector activity of VX-445 is modulated by mutations within MSD1 and the nucleotide binding domain NBD1. Here, we evaluate if mutations affecting VX-445's corrector activity also affect its potentiator activity. Responses to increasing concentrations of VX-445 were measured using the halide sensitive fluorescent assay after transfection of CFTR mutants in HEK293 cells. Results show that VX-445 potentiated gating mutants causing cystic fibrosis located in the NBDs (NBD1 G551D and NBD2 G1349D) and in the IntraCellular Loops (ICL1 G178R and ICL3 G970R). Mutations within the VX-445 binding site inhibited potentiation of G551D, contrary to some mutations located outside this site that affected its corrector activity, two of which (M212A and F224A) were found to induce CFTR gain-of-function. Potentiation of G551D was also observed with correctors VX-809 and VX-121. In conclusion, CFTR modulator VX-445 can promote channel activity of gating mutants, an effect which is dependent on the integrity of its binding site. Potentiation could also be observed with correctors VX-809 and VX-121, indicating that more generally, CFTR correctors can promote channel activity.

Background: Systematic screening for cystic fibrosis related diabetes (CFRD) is recommended for all people living with cystic fibrosis (pwCF) from the age of 10. However, adhering to these guidelines is challenging given the cumbersome nature and potential side effects of the current test of reference, the Oral Glucose Tolerance Test (OGTT). Continuous glucose monitoring (CGM) could become an alternative to OGTT, thanks to its ease of use and to the extensive information it provides.

Methods: We present the baseline data from a prospective observational multicentric French and Canadian cohort. Concomitant OGTT, CGM and collection of clinical data were performed in adult pwCF.

Results: Complete data were available in 107 participants (73 with normal glucose tolerance, 24 with impaired glucose tolerance and 10 with cystic fibrosis related diabetes), of whom 63 % were treated with Elexacaftor/Tezacaftor/Ivacaftor. Glycated hemoglobin (HbA1c), time above 7.8mmol/L and time above 10mmol/L were lower in participants with normal glucose tolerance than in those with CFRD. Several CGM parameters associated more strongly with diagnosis of CFRD at OGTT than HbA1c (Area under the ROC curves: 0.88 for time above 10mmol/L and 0.87 for time above 7.8mmol/L, vs 0.61 for HbA1c). Spending more than 10 % of the time above 7.8mmol/L detected CFRD with 100 % sensitivity and 46% specificity.

Conclusions: Certain CGM parameters correlated more closely with diagnosis of CFRD at OGTT than HbA1c in adult pwCF, with or without treatment by Elexacaftor/Tezacaftor/Ivacaftor. If future studies confirm these results prospectively, CGM could be used as a first step to screen for CFRD.

Background: People with Cystic Fibrosis (pwCF) often exhibit impaired insulin secretion, which may lead to Cystic Fibrosis-Related Diabetes (CFRD). The impact of CF variants in the complex relationship between CFTR channel function, pancreatic function, and glucose metabolism remains only partially understood.

Methods: In this multicenter study, 341 pwCF (57 % females, 79 % with pancreatic insufficiency; median age 19 yrs.) underwent an oral glucose tolerance test (OGTT) sampling glucose, insulin, and C-peptide every 30 min for 2 h to assess β-cell function, expressed by β-cell glucose sensitivity. Participants were grouped by having either a minimal function (MF) mutation on both alleles (256 pts, 75 %) or at least one residual function (RF) mutation (85 pts, 25 %). Each variant was then associated to the CFTR-chloride conductance (CC) values from the CFTR2 database. The highest CC value (from each allele) was selected as the patient' representative CC, and used to assess its relationship with β-cell glucose sensitivity.

Results: 162 pwCF (84 % of MF group) carried variants on both alleles with CC data available in the CFTR2 database. PwCF in the RF group exhibited better glucose tolerance and β-cell glucose sensitivity (p ≤ 0.001). After adjustment for sex and age, a strong positive linear association was found between CFTR-CC values and β-cell glucose sensitivity (p < 0.001), without a significant interaction with pancreatic status.

Conclusions: Clinical data, OGTT results, and in vitro CC analysis demonstrate an independent relationship between the extent of CFTR channel dysfunction and β-cell function.

Background: Prevotella melaninogenica is enriched in the lungs of people with cystic fibrosis (pwCF), yet its functional impact on respiratory tract homeostasis remains incompletely understood. Prior studies identified immune modulatory effects following lung exposure to Prevotella, but the relevance of these findings for CF infections is unknown.

Methods: The impact of P. melaninogenica on infection with the CF pathogen Staphylococcus aureus was evaluated using a mouse lung infection model and by measuring S. aureus adherence to human respiratory tract cystic fibrosis transmembrane conductance regulator (CFTR) mutant and isogenic wild-type (WT)-corrected CFBE41o- epithelial cells. Epithelial cytokine/chemokine secretion and RNA-sequencing were performed to compare P. melaninogenica-induced signaling programs in WT-corrected versus CFTR mutant cells.

Results: P. melaninogenica significantly reduced S. aureus lung infection, associated with elevated S. aureus killing by lung neutrophils and impaired S. aureus adherence to epithelial cells. Live or killed P. melaninogenica were sufficient to mediate these effects, which were dependent on TLR2. P. melaninogenica impairment of S. aureus adherence required functional CFTR, as this effect was lost in CFTR mutant cells but restored by CFTR modulators. RNA-sequencing identified several antibacterial defense pathways selectively upregulated by P. melaninogenica in WT corrected epithelial cells, correlating with higher IL-8 and IL-6 cytokine production.

Conclusions: P. melaninogenica enhanced neutrophil and epithelial defense against S. aureus, but the benefits of epithelial cell regulation by P. melaninogenica were lost with CFTR dysfunction. CFTR modulators rescued P. melaninogenica responsiveness in epithelial cells, highlighting the potential for synergistic effects of host-microbiome interactions and CFTR targeted therapies.