Neutrophils are central to inflammation in cystic fibrosis (CF) and their accumulation in airways contrasts with their inability to efficiently eliminate microorganisms. We hypothesize here that intrinsic phenotypic and functional modifications of circulating neutrophils could be present in CF patients in the absence of acute infection and under stable clinical conditions.
After information and written consent, 45 cystic fibrosis patients were recruited, as well as 25 volunteers from the Établissement Français du Sang. Blood samples were collected to analyze the phenotype of whole blood neutrophils using a panel of 24 markers and an Aurora spectral cytometer (Cytek Bioscience). Neutrophils were isolated by ficoll gradient sedimentation and spontaneous apoptosis was studied using dual Annexin-V/7-AAD.
The number of neutrophils was higher in CF patients compared to controls (7.07±3.953 106/mL vs. 3.97±1.89 106/mL, mean±SD, P<0.0001). The flow cytometry analysis showed a significant decrease in CD15, CD16, CD62L, CD10, CXCR2 expression and a significant increase in GLUT1 and LOX1 expression in neutrophils isolated from CF patients compared to the control group. In addition, we found a decrease in the proportion (mean±SD) of the conventional CD16hi/CD62Lhi neutrophils in CF patients (75.54±7.76% vs. 91.49±2.36%, P<0.0001) in favor of a CD16hi/CD62Llo subpopulation (15.57±7.85% vs. 3.63±1.77%, p<0.0001) with a very mature (CD10hi, CD33lo) and activated (CD11bhi) phenotype, and a CD16lo/CD62Lhi subpopulation (5.98±3.11% vs. 3.24±1.61%, P=0.0002) with an immature phenotype (CD10lo, CD33hi) (Fig. 1). The percentage of apoptotic neutrophils after 16h incubation was significantly lower in CF patients (69.64+4.21% vs. 84.44±1.91%, P=0.0025).
We have shown that there are persistent phenotypic changes in neutrophils in stable CF patients, with an increase in the number of circulating neutrophils associated with a defective apoptosis. Membrane markers analysis showed a dysregulation in the expression of differentiation and metabolic markers associated with the expansion of CD16lo/CD62Lhi and CD16hi/CD62lo subpopulations, as described in acute inflammation, especially in sepsis [1Bongers S.H., Chen N., van Grinsven E., y al. Kinetics of neutrophil subsets in acute, subacute, and chronic inflammation Front Immunol 2021 ; 12 : 674079
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© 2022
Publicado por Elsevier Masson SAS.