Therapeutic CFTR Correction Normalizes Systemic and Lung-Specific S1P Level Alterations Associated with Heart Failure

Abstract

Heart failure (HF) is among the main causes of death worldwide. Alterations of sphingosine-1-phosphate (S1P) signaling have been linked to HF as well as to target organ damage that is often associated with HF. S1P’s availability is controlled by the cystic fibrosis transmembrane regulator (CFTR), which acts as a critical bottleneck for intracellular S1P degradation. HF induces CFTR downregulation in cells, tissues and organs, including the lung. Whether CFTR alterations during HF also affect systemic and tissue-specific S1P concentrations has not been investigated. Here, we set out to study the relationship between S1P and CFTR expression in the HF lung. Mice with HF, induced by myocardial infarction, were treated with the CFTR corrector compound C18 starting ten weeks post-myocardial infarction for two consecutive weeks. CFTR expression, S1P concentrations, and immune cell frequencies were determined in vehicle- and C18-treated HF mice and sham controls using Western blotting, flow cytometry, mass spectrometry, and qPCR. HF led to decreased pulmonary CFTR expression, which was accompanied by elevated S1P concentrations and a pro-inflammatory state in the lungs. Systemically, HF associated with higher S1P plasma levels compared to sham-operated controls and presented with higher S1P receptor 1-positive immune cells in the spleen. CFTR correction with C18 attenuated the HF-associated alterations in pulmonary CFTR expression and, hence, led to lower pulmonary S1P levels, which was accompanied by reduced lung inflammation. Collectively, these data suggest an important role for the CFTR-S1P axis in HF-mediated systemic and pulmonary inflammation.

Cystic fibrosis transmembrane regulator correction attenuates heart failure-induced lung inflammation

“…However, difficulties in the treatment of HF patients with chronic lung phenotypes remain, as standard therapies are often complicated by contraindications. Here, we verify a HFmediated CFTR downregulation in the lung (5,13), a concept that may provide new mechanism-based treatment options for HF patients with pulmonary complications. Given the increasing evidence for an acquired CFTR dysfunction not only during HF but also in classic chronic lung diseases such as COPD and asthma (35), the indication that CFTR modulators may be useful therapeutics in the treatment of acquired CFTR abnormalities is certainly of interest to the field.…”

“…The accumulation of non-alveolar classically-activated macrophages (CD80 + SiglecF - ) associated with markedly higher TNF-α protein levels during HF compared to sham lungs ( Figure 3A ). Since TNF-α potently reduces CFTR surface expression in different cell types ( 5 , 13 , 31 ), we determined CFTR expression with an antibody targeting membrane-associated, mature CFTR protein ( 32 ). HF lungs presented with significantly lower expression levels of membrane-bound CFTR assessed by western blotting ( Figure 3B ).…”

“…Considering this, we invested in understanding the molecular mechanism by which TNF-α signaling promotes target organ function during experimental HF ( 12 ). Particularly, we showed that elevated TNF-α levels lead to considerable downregulation of the cystic fibrosis transmembrane regulator (CFTR) in the murine vasculature, heart, brain, and lung tissue ( 5 , 13 ). The importance of proper CFTR function is appreciated in cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD).…”

Restoring myocardial infarction-induced long-term memory impairment by targeting the cystic fibrosis transmembrane regulator

“…MI was induced by surgical ligation of the left anterior descending (LAD) coronary artery as described previously. 34 Briefly, mice were anaesthetised with 2–3% isoflurane (IsoFlo in room air; Abbott, Solna, Sweden), intubated with a 22-gauge angiocatheter (BD, Helsingborg, Sweden), and ventilated at a rate of 120 breaths per minute with a 200–250 μl tidal volume and 3 cm positive end expiratory pressure (MiniVent; Hugo Sachs, March, Germany). A left lateral thoracotomy was performed to expose the heart: the pericardium was opened, and the LAD was permanently ligated with 7-0 non-absorbable suture (AgnTho's; Lidingö, Sweden).…”

“…Cardiac function was assessed using MRI on a 9.4 T MR horizontal MR scanner equipped with Bruker BioSpec AVIII electronics, a quadrature volume resonator coil (112/087) for transmission and a 20 mm linear surface loop coil for reception (Bruker, Ettlingen, Germany), operating with ParaVision 6.0.1. as previously described. 34 During imaging, mice were immobilised using 1.5–2.3% isoflurane in room air, supplemented with 10% oxygen and kept at a respiration of 70–100 bpm and at 36–37 °C body temperature. Flow compensated FLASH with electrocardiogram (ECG) and respiration triggering (Stony Brook, USA) with a resolution of 0.13 × 0.13 × 1 mm 3 was used for all MR scans.…”