Losartan ameliorates TGF-β1–induced CFTR dysfunction and improves correction by cystic fibrosis modulator therapies
Michael D. Kim, … , Nathalie Baumlin, Matthias Salathe
Michael D. Kim, … , Nathalie Baumlin, Matthias Salathe
Published April 21, 2022
Citation Information: J Clin Invest. 2022;132(11):e155241. https://doi.org/10.1172/JCI155241.
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Concise Communication Inflammation Pulmonology

Losartan ameliorates TGF-β1–induced CFTR dysfunction and improves correction by cystic fibrosis modulator therapies

Abstract

Highly effective modulator therapies dramatically improve the prognosis for those with cystic fibrosis (CF). The triple combination of elexacaftor, tezacaftor, and ivacaftor (ETI) benefits many, but not all, of those with the most common F508del mutation in the CF transmembrane conductance regulator (CFTR). Here, we showed that poor sweat chloride concentration responses and lung function improvements upon initiation of ETI were associated with elevated levels of active TGF-β1 in the upper airway. Furthermore, TGF-β1 impaired the function of ETI-corrected F508del-CFTR, thereby increasing airway surface liquid (ASL) absorption rates and inducing mucus hyperconcentration in primary CF bronchial epithelial cells in vitro. TGF-β1 not only decreased CFTR mRNA, but was also associated with increases in the mRNA expression of TNFA and COX2 and TNF-α protein. Losartan improved TGF-β1–mediated inhibition of ETI-corrected F508del-CFTR function and reduced TNFA and COX2 mRNA and TNF-α protein expression. This likely occurred by improving correction of mutant CFTR rather than increasing its mRNA (without an effect on potentiation), thereby reversing the negative effects of TGF-β1 and improving ASL hydration in the CF airway epithelium in vitro. Importantly, these effects were independent of type 1 angiotensin II receptor inhibition.

Authors

Michael D. Kim, Charles D. Bengtson, Makoto Yoshida, Asef J. Niloy, John S. Dennis, Nathalie Baumlin, Matthias Salathe

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Figure 2

Losartan partially rescues TGF-β1–mediated impairments to ETI-corrected F508del-CFTR function in homozygous F508del CFBE cells in vitro.

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Losartan partially rescues TGF-β1–mediated impairments to ETI-corrected ...
(A) Fully differentiated CFBE cells were exposed to DMSO (Control), ETI, ETI plus TGF-β1 (5 ng/mL), or ETI plus TGF-β1 plus losartan (10 μM). All exposures are 24 hours except for losartan (≥21 days). The TGF-β1–mediated decrease in ETI-corrected F508del-CFTR conductance was partially rescued by losartan. n = 10, 5 CF lungs. (B) F508del-CFTR currents in A are shown as percentages of WT (non-CF) CFTR activity. (C and D) CaCC conductance (C) and transepithelial resistance (TER) (D) in ETI-treated F508del CFBE cells were not significantly changed by TGF-β1 in the presence or absence of losartan. n ≥ 8, 4 CF lungs. (E) Basolateral TGF-β1 induces greater ASL absorption (indicated by a more negative ΔASL volume) in ETI-treated CFBE cells after 24 hours, which is reversed by losartan. n = 10, 4 CF lungs. (F) TGF-β1 exposure increases mucus concentration (indicated by an increase in % mucus solids) in ETI-treated CFBE cells after 48 hours, which is reversed by losartan. n = 6, 3 CF lungs. (G) Basolateral TGF-β1 induces a significant increase in the expression of miR-145 in ETI-treated CFBE cells after 24 hours. Losartan does not reverse the increase in miR-145 expression. n = 8, 5 CF lungs. (H) CFTR mRNA expression is significantly reduced in ETI-treated CFBE cells 24 hours after TGF-β1 exposure. Losartan does not restore levels of CFTR mRNA expression. n = 8, 5 CF lungs. (I) The TGF-β1–mediated decrease in ETI-corrected F508del-CFTR conductance is partially rescued by EXP3179 (5 μM). CFBE cells were pretreated with EXP3179 for 1 hour before addition of TGF-β1. n = 9, 5 CF lungs. (J) F508del-CFTR currents in I are shown as percentages of WT (non-CF) CFTR activity. (K) ASL absorption induced by TGF-β1 in ETI-treated CFBE cells is reversed by EXP3179. n = 6, 4 CF lungs. Data are shown as mean ± SEM. *P < 0.05, 1-way ANOVA followed by Holm-Šidák (A, C, E, F, I, and K) and Friedman test (D, G, and H) after assessing normality by Shapiro-Wilk.