Detection of cytokines in nasal lavage samples of patients with cystic fibrosis: comparison of two different cytokine detection assays.

BACKGROUND: Cystic fibrosis (CF) is a genetic multisystem disorder. Inflammatory processes, which presumably begin early in infancy, play a crucial role in the progression of the disease. The detection of inflammatory biomarkers, especially in the airways, has therefore gained increasing attention. Due to improved treatment options, patients with CF produce less sputum. Nasal lavage samples therefore represent a promising alternative to induced sputum or bronchoalveolar lavage specimens. However, methodology of cytokine measurements is not standardised and comparisons of results are therefore often difficult. The aim of this study was to identify suitable detection methods of cytokines in nasal lavage samples by comparison of two different assays. METHODS: Nasal lavage samples were obtained from the same patient at the same time by trained respiratory physiotherapists using a disposable syringe and 10 ml of 0.9% sodium chloride per nostril during outpatient visits. The cytokines IL-17 A, IL-2, IL-6 and IL-10 were measured using two different assays (BD™ and Milliplex®), which have already been applied in sputum and nasal lavage samples, despite different lower detection limits. RESULTS: 22 participants were included in the study. In 95.5% of measurements, values were below the limit of detection with respect to the BD™ assay. Only IL-6 could be detected in approximately half of the patients. Individual cytokine levels were considerably higher when measured with Milliplex®, which is also reflected in a statistically significant manner (p = < 0.01). CONCLUSION: The right choice of analysis method is crucial for measuring inflammatory markers in nasal lavage samples. Compared to the literature, Milliplex® showed higher detection rates and similar concentrations to other studies. TRIAL REGISTRATION: Ethics approval was obtained from the ethics committee at Medical University of Innsbruck (EK Nr: 1055/2022).

Personalized medicine with drugs targeting the underlying protein defect in cystic fibrosis: is monitoring of treatment response necessary?

Cystic fibrosis (CF) is caused by two mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. In the last years, drugs targeting the underlying protein defect like lumacaftor/ivacaftor (LUM/IVA) or tezacaftor/ivacaftor (TEZ/IVA) and more recently elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) were admitted. Outcome parameters evaluating therapy response like forced expiratory pressure in 1 s (FEV1), body mass index (BMI) or the efficacy of CFTR function in sweat glands showed improvement in several cases. Other, CFTR biomarkers were analysed rarely. This prospective observational study was aimed at evaluating CFTR function in patients treated with different CFTR modulators together with common valid clinical outcome parameters at standardized appointments (day 0, week 2, 4, 16). We followed four patients with the same mutation (F508del-CFTR), sex, age and disease severity. Monitoring focused on lung function, gastrointestinal aspects and CFTR function of sweat glands, nasal and intestinal epithelium. Sweat tests were performed by pilocarpine iontophoresis. Nasal potential difference (NPD) measured transepithelial voltage in vivo and potential increased when CFTR function improved. Rectal biopsies were obtained for intestinal current measurements (ICM) ex vivo. Intestinal CFTR function was assessed by stimulating chloride secretion with different reagents. Response to CFTR modulators regarding clinical outcome parameters was rather variable. A sweat chloride reduction of 35.3 mmol/L, nasal CFTR rescue of 4.4% and fivefold higher CFTR function in the intestine was seen at week 16 post-LUM/IVA. Due to our monitoring, we identified a non-responder to LUM/IVA and TEZ/IVA. In case of ELX/TEZ/IVA, clinical parameters and CFTR bioassays improved and were concordant. Although our cohort is small, results emphasize that non-responders exist and conclusions could not be drawn if patients were not monitored. Data on CFTR function can confirm or disprove ongoing CFTR dysfunction and might be helpful selectively. Non-responders need other alternative therapy options as demonstrated with ELX/TEZ/IVA.