(403) Trikafta® modulator therapy reduces Burkholderia cenocepacia burden in an in vitro airway infection model

Background: Trikafta® modulator therapy for people with cystic fibrosis (pwCF) carrying at least one copy of the F508del mutation of the CF transmembrane conductance regulator (CFTR) protein has demonstrated reduced clinical exacerbations, and increased FEV₁ and general wellbeing. Trikafta functions to rescue the misfolded CFTR protein and traffic it to the surface membrane of airway cells, thus potentially restoring normal airway physiology such as airway secretions, pH balance and cilia movement. However, it is unknown whether Trikafta will also help reduce pathogenic infections and prevalence in pwCF. One such deadly pathogen is Burkholderia cenocepacia (Bc) that can cause variable lung infections, ranging from asymptomatic, chronic or ‘cepacia syndrome’ as characterized by a rapid decline in lung function. Since pwCF carrying Bc are not included in Trikafta clinical trials, we proposed to use in vitro primary CF human bronchial epithelial (CF-HBE) 3D cultures to investigate the effects of Trikafta on Bc infections.

Methods: Fully-differentiated primary CF-HBE cells (3-4 donors) at air-liquid interface (ALI) were treated with Trikafta (Elexacaftor/Tezacaftor/Ivacaftor) prior to Bc (lab strain K56-2 labeled with DsRed; MOI 0.1-1) infection on the apical surface. Response of CF-HBE cultures to Trikafta was confirmed by measuring CFTR protein expression, and CFTR ion channel function. Airway physiology including ciliary beat frequency (CBF), pH of the airway-surface liquid (ASL) and expression of antimicrobial proteins such as SPLUNC1 (activity against Gram-negative bacteria) were recorded after Trikafta treatment. Bc growth was measured by immunofluorescence in both non-CF HBE (NHBE) and CF-HBE ± Trikafta treated cultures.

Results: Trikafta treatment in CF-HBE cultures significantly restored CFTR protein expression at the apical membrane, and also CFTR ion channel function. Downstream physiology, including CBF and pH of the ASL was significantly restored to levels observed in NHBE cultures. SPLUNC1 antimicrobial expression was reduced in the ASL secretions of CF-HBE compared to NHBE, but was significantly increased after Trikafta treatment. Furthermore, Bc (K56-2) infections on CF-HBE cultures were significantly reduced with pre-treatment with Trikafta, despite greater burden in CF-HBE than NHBE cultures (Figure 1). However, Bc infection also appeared to interfere with Trikafta efficacy by reducing CFTR expression and function compared to non-infected CF-HBE+Trikafta cultures, although not to the extent of non-Trikafta treated CF-HBE cultures.

Conclusions: The risk of Bc infections in pwCF may be reduced with modulator therapy such as Trikafta, although Bc may also interfere with Trikafta efficacy. Reduction of Bc infections by Trikafta treatment given to pwCF already colonized with Bc remains to be determined. Taken together, our data indicate that starting Trikafta treatment could be beneficial to pwCF to prevent infections by pathogens such as Bc.

Acknowledgements: This work was supported by the Cure CF Columbus (C3) RDP Trainee Award (AWD-105830 to RR).

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