ABSTRACT
Background: The advent of highly effective modulator therapies (HEMTs), including elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA), for treatment of cystic fibrosis (CF) has resulted in remarkable clinical improvement for modulator-naive patients and for those who have been treated with prior modulator therapies. Intranasal micro-optical coherence tomography (muOCT) has detected functional abnormalities in the mucociliary apparatus of people with CF. The objectivewas to characterize the effects of ELX/TEZ/ IVA on nasal mucociliary clearance by muOCT and monitor the clinical changes conferred as a way to understand the effects. Method(s): Of 26 individuals aged 12 and older with at least one F508del mutation recruited, 24 were enrolled and followed over three visits: baseline and 1 (visit 2) and 6 months (visit 4) after initiation of ELX/TEZ/IVA therapy;the COVID-19 pandemic affected visit windows. Intranasal muOCT imaging was conducted at baseline and visit 2 as previously described;additional imaging for 18 months (visit 5) is in progress. Clinical outcomes, including percentage predicted forced expiratory volume in 1 second (FEV1pp) and sweat chloride levels were computed as part of the parent Prospective Study to Evaluate Biological and Clinical Effects of Significantly Corrected CFTR Function (PROMISE study). A blinded investigator team analyzed in vivo muOCT parameters including mucociliary transport (MCT) rate, ciliary beat frequency (CBF), and periciliary liquid depth (PCL) after devising an improved stabilization algorithm. Analysis of airway surface liquid (ASL) depthswas excluded because of the limited number of cases in which the necessary condition for measurement,which is preservation of a clear air layer between the mucus layer and the probe, was satisfied. Result(s): Twenty-three subjects completed visits 1 and 2, and 18 completed visits 1, 2, and 4. Average age at baselinewas 27 +/- 8.7, 69% were female, and 43% were on prior two-drug modulator therapy. No significant change in body mass index was found between the visits. FEV1pp increased significantly (10.9%, 95% CI, 76.1-98.4%) by visit 2 and persisted at visit 4 (10.6%, 95% CI, 87.7-107.0;p < 0.001). Sweat chloride levels decreased significantly at visit 2 (-36.6 mmol/L, 95% CI, 40.9-54.9 mmol/L) and visit 4 (-41.3 mmol/L, 95% CI, 34.9-51.8 mmol/L) at visit 4 ( p < 0.001). Analysis of muOCT images revealed significant improvement in MCT rate (2.8 +/- 1.5 mm/ min at baseline vs 4.0 +/- 1.5 mm/min at visit 2, p = 0.048), although no discernable changes were noted in CBF or PCL. When stratified based on use of prior modulator therapy, no significant differences were found for any muOCT metric. No significant correlations between change in MCT rates and change in FEV1pp or sweat chloride from baseline to visit 2were found. Conclusion(s): Treatment with ELX/TEZ/IVA in people with CF, including those that were treatment naive and those on prior modulator therapy, resulted in significant, sustained improvement in lung function and decreases in sweat chloride levels at ~10 months, consistent with recently published reports. Functional improvements in MCTratewere evident after initiation of ELX/TEZ/IVA therapy, which may partially explain the findings of better whole-lung mucus clearance and reduction in chronic infections reported previously. muOCT imaging in people with CF is sensitive to the treatment effect of HEMT and suggests better mucociliary transport as a mechanism of action underlying the clinical benefits for lung health. Acknowledgements: On behalf of the PROMISE investigatorsCopyright © 2022, European Cystic Fibrosis Society. All rights reserved
ABSTRACT
RATIONALE: Micro optical coherence tomography (μOCT) is a minimally invasive intranasal imaging technique that can determine cellular and functional dynamics of respiratory epithelia at 1-μm resolution, enabling real time visualization and quantification of ciliary motion, inflammation, and mucus transport. Multiple abnormalities including reduced mucociliary transport were reported in patients with cystic fibrosis (Leung et al., Sci Trans Med 2019). Severe acute respiratory syndrome coronavirus (SARS-CoV-2), causative agent of COVID- 19, binds via ACE2 receptors, highly expressed in the ciliated and secretory cells of the nasal epithelium. We hypothesized that respiratory epithelial cell dysfunction in COVID-19 will manifest as abnormal mucociliary transport due to reduced ciliated cell function, features readily visualized by μOCT. METHODS: Symptomatic outpatients aged ≥ 18 years were recruited within 7 days of symptom onset and known SARS-CoV-2 RT-PCR positivity. Detailed clinical history and nasal swab for PCR quantification of viral RNA were obtained. Subjects were imaged inside a custom designed negative pressure isolation booth to minimize risk of virus transmission. Following inspection with a rhinoscope, the μOCT probe was maneuvered into the inferior meatus while acquiring data from approximately five discrete sites at both turbinate and floor of each nare. Long-term follow up, including clinical outcomes at 21 days were collected. Data was interpreted in comparison to previously imaged healthy controls. RESULTS: Eight subjects underwent imaging without complications, and additional enrollment is in progress. Mean age was 29.4 years (SD 8.2), and average duration of illness from symptom onset to imaging was 8.8 days (SD 4.3). Most common symptoms reported were fatigue (75%), headache, anosmia, fever, and sore throat (50% each). Viral load (mean log10) at time of imaging was 4.3 copies per mL. Imaging abnormalities identified to date (N=5) included denuded epithelium, presence of excessive mucus (Figure.1,B), and increased inflammatory cell counts (Figure.1,C) compared to healthy control (Figure.1,A). Reduced mucociliary transport (2.7 ± 0.3 mm/min COVID-19 vs 11.2 ± 0.8 mm/min healthy controls, P= 0.0016) and diminished periciliary liquid depth (4.3± 0.8 μm COVID-19 vs 6.8 ± 0.3 μm healthy controls, P= 0.028) were evident. CONCLUSION: Subjects with mild but symptomatic COVID-19 exhibit functional abnormalities of the respiratory mucosa, including delayed mucociliary transport. Mucociliary dysfunction in COVID-19, as also seen in Syrian hamsters (See Li Q et al., ATS 2021 Abstract), may increase risk for descending infection and disease progression. μOCT imaging may be a useful tool to evaluate prognosis, disease progression, and monitor emerging therapy.
ABSTRACT
RATIONALE: SARS-CoV-2 causes COVID-19 disease and infects respiratory epithelial cells, but how it affects ciliated cell function and the mucociliary transport apparatus is unknown. Abnormal mucociliary function could predispose to COVID-19 progression and/or secondary infection. Micro-optical coherence tomography (μOCT) is a novel method to simultaneously visualize and quantify the functional microanatomy of airways. Here, we established a hamster model of COVID-19 and evaluated their tracheas by μOCT. METHODS: Adult golden Syrian hamsters were inoculated intranasally with 3.2 × 105 (high dose, HD, N=4) or 3.2 × 104 (low dose, LD, N=4) plaque-forming units of SARS-CoV-2 (WA/1 strain). Clinical signs were monitored daily, nasal brushes collected intermittently, and hamsters were euthanized seven days (D7) after inoculation. Tracheas were imaged by μOCT, nasal washes and bronchial alveolar lavage fluid (BALF) from right lung lobes were collected for quantitation of viral load by qRT-PCR, and left lungs were inflated with and fixed in 10% neutral buffered formalin for histological analysis. Age-matched hamsters were used as uninfected controls (N=5). RESULTS: SARS-CoV-2 hamsters lost weight through D7 in dose-dependent fashion (-11% in HD vs. -4% in LD, p=0.02) and HD hamsters showed moderate lethargy. Nasal brushes on D4 and nasal washes on D7 contain 105-106 genome copies of virus while BALF on D7 was less than 104 genome copies and intermittently detected in LD. Histology demonstrated patchy and multifocal interstitial pneumonia (type II pneumocyte hyperplasia and mononuclear cell infiltrate), with ∼20% area affected in HD that was more variable in LD. Functional microanatomy of tracheas revealed diminished area of active ciliary beating (control 18 ± 2 vs. LD 7 ± 1%, p=0.0002, control vs. HD 9 ± 1%, p=0.001), reduced ciliary beat frequency (control 10.88 ± 0.70 vs. LD 8.83 ± 0.34 Hz, p=0.01, control vs. HD 8.26 ± 0.33 Hz, p=0.001), and decreased periciliary liquid depth (control 6.41 ± 0.18 vs. HD 5.61± 0.12 μ m, p=0.027). Mucociliary transport rate was diminished (control 0.84 ± 0.19 vs. LD 0.48 ± 0.16 vs. HD 0.37 ± 0.13 mm/min) although not statistically significant. Additional cohorts are in progress. CONCLUSION: SARS-Cov-2 infected hamsters exhibit reduced body weight, high viral load, and histopathological injury through 7 days. SARS-CoV-2 caused functional deficits of the mucociliary transport apparatus, consistent with early findings in COVID-19 patients (see Vijaykumar et al.). Abnormal ciliated cell function is important to SARS-CoV-2 pathogenesis, and may help monitor progression and represent a treatment opportunity for COVID-19.