WS09.01CFTR activity in nasal epithelia from subjects with different genotypes

Objectives

The human nasal epithelial (hNE) cells are an interesting ex-vivo model to perform molecular and functional studies on CFTR. Reference values for normal CFTR activity are important to assess CFTR dysfunction in people with cystic fibrosis (pwCF) and its rescue by modulators.

Methods

We collected hNE cells (by nasal brushing) from a cohort of about forty non-CF donors. We generated well-differentiated nasal epithelia in air-liquid interface, and then we performed short-circuit current measurements to evaluate CFTR-dependent Cl- secretion. We opted for two different experimental conditions: first, we performed the measurements using symmetrical Cl- solution (standard condition, SC) and then by imposing a Cl- gradient (gradient condition, GC). This latter condition allowed us to maximize the anion transport by CFTR.

Results

Our data showed that, under SC, CFTR activities measured in our cohort varied between 10 and 35 µA/cm². In the majority of the subjects, when we switched to the GC, we observed a two-fold increase in CFTR activity. However, two small groups of subjects had different behaviours. Interestingly, both groups were composed by cultures showing the lowest levels of CFTR activity (ranging from 10 to < 20 µA/cm²) in SC. However, in GC, the first group showed a higher improvement, around 3-fold, in CFTR activity. The second group showed a limited increase, around 1.5-fold, with CFTR-mediated currents that were lower than 30 µA/cm². Interestingly we found that the second group was composed by obligate carriers together with subjects that were actually unidentified carriers present in the cohort.

Conclusion

These results support the thesis of the robustness of the nasal model as a predictive model, that allowed us to detect subclinical CFTR dysfunction.

Supported by Fondazione Ricerca Fibrosi Cistica grants FFC #9/2019 and FFC #10/2021, and Italian Ministry of Health grant PNRR-MR1-2023-12378412.