Histopathology underlying environmental enteric dysfunction in a cohort study of undernourished children in Bangladesh, Pakistan, and Zambia compared with United States children.

BACKGROUND: Environmental enteric dysfunction (EED) is an asymptomatic intestinal disorder associated with growth impairment, delayed neurocognitive development, and impaired oral vaccine responses. OBJECTIVES: We set out to develop and validate a histopathologic scoring system on duodenal biopsies from a cohort study of children with growth failure in Bangladesh, Pakistan, and Zambia ("EED") with reference to biopsies from United States children with no clinically reported histologic pathology (referred to hereafter as "normal") or celiac disease. METHODS: Five gastrointestinal pathologists evaluated 745 hematoxylin and eosin slide images from 291 children with EED (mean age: 1.6 y) and 66 United States children (mean age: 6.8 y). Histomorphologic features (i.e., villus/crypt architecture, goblet cells, epithelial and lamina propria acute/chronic inflammation, Brunner's glands, Paneth cells, epithelial detachment, enterocyte injury, and foveolar metaplasia) were used to score each histopathologic slide. Generalized estimating equations were used to determine differences between EED, normal, and celiac disease, and receiver operating characteristic curves were used to assess predictive value. RESULTS: Biopsies from the duodenal bulb showed higher intramucosal Brunner's gland scores and lower intraepithelial lymphocyte scores than from the second or third parts of the duodenum (D2/3), so only D2/3 were included in the final analysis. Although 7 parameters differed significantly between EED and normal biopsies in regression models, only 5 (blunted villus architecture, increased intraepithelial lymphocytosis, goblet cell depletion, Paneth cell depletion, and reduced intramucosal Brunner's glands) were required to create a total score percentage (TSP-5) that correctly identified EED against normal biopsies (AUC: 0.992; 95% CI: 0.983, 0.998). Geographic comparisons showed more severe goblet cell depletion in Bangladesh and more marked intraepithelial lymphocytosis in Pakistan. CONCLUSIONS: This scoring system involving 5 histologic parameters demonstrates very high discrimination between EED and normal biopsies, indicating that this scoring system can be applied with confidence to studies of intestinal biopsies in EED.

Emerging Hybrid Intracoronary Imaging Technologies and Their Applications in Clinical Practice and Research.

Intravascular ultrasound and optical coherence tomography are used with increasing frequency for the care of coronary patients and in research studies. These imaging tools can identify culprit lesions in acute coronary syndromes, assess coronary stenosis severity, guide percutaneous coronary intervention (PCI), and detect vulnerable plaques and patients. However, they have significant limitations that have stimulated the development of multimodality intracoronary imaging catheters, which provide improvements in assessing vessel wall pathology and guiding PCI. Prototypes combining 2 or even 3 imaging probes with complementary attributes have been developed, and several multimodality systems have already been used in patients, with near-infrared spectroscopy intravascular ultrasound-based studies showing promising results for the identification of high-risk plaques. Moreover, postmortem histology studies have documented that hybrid imaging catheters can enable more accurate characterization of plaque morphology than standalone imaging. This review describes the evolution in the field of hybrid intracoronary imaging; presents the available multimodality catheters; and discusses their potential role in PCI guidance, vulnerable plaque detection, and the assessment of endovascular devices and emerging pharmacotherapies targeting atherosclerosis.

Reduced sialylation of airway mucin impairs mucus transport by altering the biophysical properties of mucin.

Mucus stasis is a pathologic hallmark of muco-obstructive diseases, including cystic fibrosis (CF). Mucins, the principal component of mucus, are extensively modified with hydroxyl (O)-linked glycans, which are largely terminated by sialic acid. Sialic acid is a negatively charged monosaccharide and contributes to the biochemical/biophysical properties of mucins. Reports suggest that mucin sialylation may be altered in CF; however, the consequences of reduced sialylation on mucus clearance have not been fully determined. Here, we investigated the consequences of reduced sialylation on the charge state and conformation of the most prominent airway mucin, MUC5B, and defined the functional consequences of reduced sialylation on mucociliary transport (MCT). Reduced sialylation contributed to a lower charged MUC5B form and decreased polymer expansion. The inhibition of total mucin sialylation de novo impaired MCT in primary human bronchial epithelial cells and rat airways, and specific α-2,3 sialylation blockade was sufficient to recapitulate these findings. Finally, we show that ST3 beta-galactoside alpha-2,3-sialyltransferase (ST3Gal1) expression is downregulated in CF and partially restored by correcting CFTR via Elexacaftor/Tezacaftor/Ivacaftor treatment. Overall, this study demonstrates the importance of mucin sialylation in mucus clearance and identifies decreased sialylation by ST3Gal1 as a possible therapeutic target in CF and potentially other muco-obstructive diseases.

Reduced Sialylation of Airway Mucin Impairs Mucus Transport by Altering the Biophysical Properties of Mucin.

Mucus stasis is a pathologic hallmark of muco-obstructive diseases, including cystic fibrosis (CF). Mucins, the principal component of mucus, are extensively modified with hydroxyl (O)-linked glycans, which are largely terminated by sialic acid. Sialic acid is a negatively charged monosaccharide and contributes to the biochemical/biophysical properties of mucins. Reports suggest that mucin sialylation may be altered in CF; however, the consequences of reduced sialylation on mucus clearance have not been fully determined. Here, we investigated the consequences of reduced sialylation on the charge state and conformation of the most prominent airway mucin, MUC5B, and defined the functional consequences of reduced sialylation on mucociliary transport (MCT). Reduced sialylation contributed to a lower charged MUC5B form and decreased polymer expansion. The inhibition of total mucin sialylation de novo impaired MCT in primary human bronchial epithelial cells and rat airways, and specific α-2,3 sialylation blockade was sufficient to recapitulate these findings. Finally, we show that ST3 beta-galactoside alpha-2,3-sialyltransferase (ST3Gal1) expression is downregulated in CF and partially restored by correcting CFTR via Elexacaftor/Tezacaftor/Ivacaftor treatment. Overall, this study demonstrates the importance of mucin sialylation in mucus clearance and identifies decreased sialylation by ST3Gal1 as a possible therapeutic target in CF and potentially other muco-obstructive diseases.

Metachrony drives effective mucociliary transport via a calcium-dependent mechanism.

The mucociliary transport apparatus is critical for maintaining lung health via the coordinated movement of cilia to clear mucus and particulates. A metachronal wave propagates across the epithelium when cilia on adjacent multiciliated cells beat slightly out of phase along the proximal-distal axis of the airways in alignment with anatomically directed mucociliary clearance. We hypothesized that metachrony optimizes mucociliary transport (MCT) and that disruptions of calcium signaling would abolish metachrony and decrease MCT. We imaged bronchi from human explants and ferret tracheae using micro-optical coherence tomography (µOCT) to evaluate airway surface liquid depth (ASL), periciliary liquid depth (PCL), cilia beat frequency (CBF), MCT, and metachrony in situ. We developed statistical models that included covariates of MCT. Ferret tracheae were treated with BAPTA-AM (chelator of intracellular Ca2+), lanthanum chloride (nonpermeable Ca2+ channel competitive antagonist), and repaglinide (inhibitor of calaxin) to test calcium dependence of metachrony. We demonstrated that metachrony contributes to mucociliary transport of human and ferret airways. MCT was augmented in regions of metachrony compared with nonmetachronous regions by 48.1%, P = 0.0009 or 47.5%, P < 0.0020 in humans and ferrets, respectively. PCL and metachrony were independent contributors to MCT rate in humans; ASL, CBF, and metachrony contribute to ferret MCT rates. Metachrony can be disrupted by interference with calcium signaling including intracellular, mechanosensitive channels, and calaxin. Our results support that the presence of metachrony augments MCT in a calcium-dependent mechanism.NEW & NOTEWORTHY We developed a novel imaging-based analysis to detect coordination of ciliary motion and optimal coordination, a process called metachrony. We found that metachrony is key to the optimization of ciliary-mediated mucus transport in both ferret and human tracheal tissue. This process appears to be regulated through calcium-dependent mechanisms. This study demonstrates the capacity to measure a key feature of ciliary coordination that may be important in genetic and acquired disorders of ciliary function.

Two-site microendoscopic imaging probe for simultaneous three-dimensional imaging at two anatomic locations in tissues.

Systems that can image in three dimensions at cellular resolution and across different locations within an organism may enable insights into complex biological processes, such as immune responses, for which a single location measurement may be insufficient. In this Letter, we describe an in vivo two-site imaging probe (TIP) that can simultaneously image two anatomic sites with a maximum separation of a few centimeters. The TIP consists of two identical bendable graded index (GRIN) lenses and is demonstrated by a two-photon two-color fluorescence imaging system. Each GRIN lens has a field of view of 162 × 162 × 170 µm3, a nominal numerical aperture of 0.5, a magnification of 0.7, and working distances of 0.2 mm in air for both ends. A blind linear unmixing algorithm is applied to suppress bleedthrough between channels. We use this system to successfully demonstrate two-site two-photon two-color imaging of two biomedically relevant samples, i.e., (1) a mixture of two autofluorescent anti-cancer drugs and (2) a live hybrid tumor consisting of two spectrally distinct fluorescent cell lines.

Ultrathin-strut versus thin-strut stent healing and outcomes in preclinical and clinical subjects.

BACKGROUND: Compared with thin-strut durable-polymer drug-eluting stents (DP-DES), ultrathin-strut biodegradable-polymer sirolimus-eluting stents (BP-SES) improve stent-related clinical outcomes in patients undergoing percutaneous coronary intervention (PCI). Reduced stent strut thickness is hypothesised to underlie these benefits, but this conjecture remains unproven. AIMS: We aimed to assess the impact of strut thickness on stent healing and clinical outcomes between ultrathin-strut and thin-strut BP-SES. METHODS: First, we performed a preclinical study of 8 rabbits implanted with non-overlapping thin-strut (diameter/thickness 3.5 mm/80 µm) and ultrathin-strut (diameter/thickness 3.0 mm/60 µm) BP-SES in the infrarenal aorta. On day 7, the rabbits underwent intravascular near-infrared fluorescence optical coherence tomography (NIRF-OCT) molecular-structural imaging of fibrin deposition and stent tissue coverage, followed by histopathological analysis. Second, we conducted an individual data pooled analysis of patients enrolled in the BIOSCIENCE and BIOSTEMI randomised PCI trials treated with ultrathin-strut (n=282) or thin-strut (n=222) BP-SES. The primary endpoint was target lesion failure (TLF) at 1-year follow-up, with a landmark analysis at 30 days. RESULTS: NIRF-OCT image analyses revealed that ultrathin-strut and thin-strut BP-SES exhibited similar stent fibrin deposition (p=0.49) and percentage of uncovered stent struts (p=0.63). Histopathological assessments corroÂborated these findings. In 504 pooled randomised trial patients, TLF rates were similar for those treated with ultrathin-strut or thin-strut BP-SES at 30-day (2.5% vs 1.8%; p=0.62) and 1-year follow-up (4.3% vs 4.7%; p=0.88). CONCLUSIONS: Ultrathin-strut and thin-strut BP-SES demonstrate similar early arterial healing profiles and 30-day and 1-year clinical outcomes.

Longitudinal improvements in clinical and functional outcomes following initiation of elexacaftor/tezacaftor/ivacaftor in patients with cystic fibrosis.

Background: Use of elexacaftor/tezacaftor/ivacaftor (ETI) for treatment of cystic fibrosis (CF) has resulted in unprecedented clinical improvements necessitating development of outcome measures for monitoring disease course. Intranasal micro-optical coherence tomography (µOCT) has previously helped detect and characterize mucociliary abnormalities in patients with CF. This study was done to determine if µOCT can define the effects of ETI on nasal mucociliary clearance and monitor changes conferred to understand mechanistic effects of CFTR modulators beyond CFTR activation. Methods: 26 subjects, with at least 1 F508del mutation were recruited and followed at baseline (visit 1), +1 month (visit 2) and +6 months (visit 4) following initiation of ETI therapy. Clinical outcomes were computed at visits 1, 2 and 4. Intranasal µOCT imaging and functional metrics analysis including mucociliary transport rate (MCT) estimation were done at visits 1 and 2. Results: Percent predicted forced expiratory volume in 1 s (ppFEV1) showed a significant increase of +10.9 % at visit 2, which sustained at visit 4 (+10.6 %). Sweat chloride levels significantly decreased by -36.6 mmol/L and -41.3 mmol/L at visits 2 and 4, respectively. µOCT analysis revealed significant improvement in MCT rate (2.8 ± 1.5, visit 1 vs 4.0 ± 1.5 mm/min, visit 2; P = 0.048). Conclusions: Treatment with ETI resulted in significant and sustained clinical improvements over 6 months. Functional improvements in MCT rate were evident within a month after initiation of ETI therapy indicating that µOCT imaging is sensitive to the treatment effect of HEMT and suggests improved mucociliary transport as a probable mechanism of action underlying the clinical benefits.

Transgenic ferret models define pulmonary ionocyte diversity and function.

Speciation leads to adaptive changes in organ cellular physiology and creates challenges for studying rare cell-type functions that diverge between humans and mice. Rare cystic fibrosis transmembrane conductance regulator (CFTR)-rich pulmonary ionocytes exist throughout the cartilaginous airways of humans1,2, but limited presence and divergent biology in the proximal trachea of mice has prevented the use of traditional transgenic models to elucidate ionocyte functions in the airway. Here we describe the creation and use of conditional genetic ferret models to dissect pulmonary ionocyte biology and function by enabling ionocyte lineage tracing (FOXI1-CreERT2::ROSA-TG), ionocyte ablation (FOXI1-KO) and ionocyte-specific deletion of CFTR (FOXI1-CreERT2::CFTRL/L). By comparing these models with cystic fibrosis ferrets3,4, we demonstrate that ionocytes control airway surface liquid absorption, secretion, pH and mucus viscosity-leading to reduced airway surface liquid volume and impaired mucociliary clearance in cystic fibrosis, FOXI1-KO and FOXI1-CreERT2::CFTRL/L ferrets. These processes are regulated by CFTR-dependent ionocyte transport of Cl- and HCO3-. Single-cell transcriptomics and in vivo lineage tracing revealed three subtypes of pulmonary ionocytes and a FOXI1-lineage common rare cell progenitor for ionocytes, tuft cells and neuroendocrine cells during airway development. Thus, rare pulmonary ionocytes perform critical CFTR-dependent functions in the proximal airway that are hallmark features of cystic fibrosis airway disease. These studies provide a road map for using conditional genetics in the first non-rodent mammal to address gene function, cell biology and disease processes that have greater evolutionary conservation between humans and ferrets.

Red ginseng aqueous extract improves mucociliary transport dysfunction and histopathology in CF rat airways.

BACKGROUND: We previously discovered that Korean red ginseng aqueous extract (RGAE) potentiates the TMEM16A channel, improved mucociliary transport (MCT) parameters in CF nasal epithelia in vitro, and thus could serve as a therapeutic strategy to rescue the MCT defect in cystic fibrosis (CF) airways. The hypothesis of this study is that RGAE can improve epithelial Cl- secretion, MCT, and histopathology in an in-vivo CF rat model. METHODS: Seventeen 4-month old CFTR-/- rats were randomly assigned to receive daily oral control (saline, n = 9) or RGAE (Ginsenosides 0.4mg/kg/daily, n = 8) for 4 weeks. Outcomes included nasal Cl- secretion measured with the nasal potential difference (NPD), functional microanatomy of the trachea using micro-optical coherence tomography, histopathology, and immunohistochemical staining for TMEM16a. RESULTS: RGAE-treated CF rats had greater mean NPD polarization with UTP (control = -5.48 +/- 2.87 mV, RGAE = -9.49 +/- 2.99 mV, p < 0.05), indicating, at least in part, potentiation of UTP-mediated Cl- secretion through TMEM16A. All measured tracheal MCT parameters (airway surface liquid, periciliary liquid, ciliary beat frequency, MCT) were significantly increased in RGAE-treated CF rats with MCT exhibiting a 3-fold increase (control, 0.45+/-0.31 vs. RGAE, 1.45+/-0.66 mm/min, p < 0.01). Maxillary mucosa histopathology was markedly improved in RGAE-treated cohort (reduced intracellular mucus, goblet cells with no distention, and shorter epithelial height). TMEM16A expression was similar between groups. CONCLUSION: RGAE improves TMEM16A-mediated transepithelial Cl- secretion, functional microanatomy, and histopathology in CF rats. Therapeutic strategies utilizing TMEM16A potentiators to treat CF airway disease are appropriate and provide a new avenue for mutation-independent therapies.

Engineered tRNAs suppress nonsense mutations in cells and in vivo.

Nonsense mutations are the underlying cause of approximately 11% of all inherited genetic diseases1. Nonsense mutations convert a sense codon that is decoded by tRNA into a premature termination codon (PTC), resulting in an abrupt termination of translation. One strategy to suppress nonsense mutations is to use natural tRNAs with altered anticodons to base-pair to the newly emerged PTC and promote translation2-7. However, tRNA-based gene therapy has not yielded an optimal combination of clinical efficacy and safety and there is presently no treatment for individuals with nonsense mutations. Here we introduce a strategy based on altering native tRNAs into  efficient suppressor tRNAs (sup-tRNAs) by individually fine-tuning their sequence to the physico-chemical properties of the amino acid that they carry. Intravenous and intratracheal lipid nanoparticle (LNP) administration of sup-tRNA in mice restored the production of functional proteins with nonsense mutations. LNP-sup-tRNA formulations caused no discernible readthrough at endogenous native stop codons, as determined by ribosome profiling. At clinically important PTCs in the cystic fibrosis transmembrane conductance regulator gene (CFTR), the sup-tRNAs re-established expression and function in cell systems and patient-derived nasal epithelia and restored airway volume homeostasis. These results provide a framework for the development of tRNA-based therapies with a high molecular safety profile and high efficacy in targeted PTC suppression.

High-speed reflectance confocal microscopy of human skin at 1251-1342 nm.

OBJECTIVES: Reflectance confocal microscopy (RCM) is an imaging method that can noninvasively visualize microscopic features of the human skin. The utility of RCM can be further improved by increasing imaging speed. In this paper, we report high-speed RCM imaging of human skin with a frame rate that is over 10 times faster and an area imaging rate that is 6-9 times faster than those of commercially available RCM devices. METHODS: The higher imaging speed was achieved using a high-speed RCM technique, termed spectrally encoded confocal microscopy (SECM). SECM uses a diffraction grating and a high-speed, wavelength-swept source to conduct confocal imaging at a very high rate. We developed a handheld SECM probe using a scanned-grating approach. The SECM probe was used in conjunction with a wavelength-swept source with a spectral band of 1251-1342 nm. RESULTS: The SECM probe achieved high lateral resolution of 1.3-1.6 µm and an axial resolution of 3.5 µm. SECM images of the human skin (image size = 439 × 439 µm2 ) obtained at 100 frames/s clearly show previously reported RCM features of the human skin in vivo with adequate image quality. The fast imaging speed allowed for the rapid acquisiton of volumetric SECM image data (200 frames covering a depth range of 200 µm) within 2 s. The use of 1251-1342 nm provided sufficient signal level and contrast required to visualize key cellular morphologic features. CONCLUSIONS: These preliminary results demonstrate that high-speed SECM imaging of the human skin at 1251-1342 nm is feasible.

OCT Emerging Technologies: Coronary Micro-optical Coherence Tomography.

Optical coherence tomography (OCT) is an imaging modality that is used in a significant number of interventional cardiology procedures. Key structural changes occurring within the vessel wall, including presence of neutrophils, macrophages, monocytes, and vascular smooth muscle cells, are below the resolution of clinical intracoronary OCT. To address this challenge, a new form of OCT with 1 to 2 µm resolution, termed micro-OCT (µOCT), has been developed. This review article summarizes the ability of µOCT technology to visualize coronary microstructures and discusses its clinical implications.

STAT3 mutation-associated airway epithelial defects in Job syndrome.

BACKGROUND: Job syndrome is a disease of autosomal dominant hyper-IgE syndrome (AD-HIES). Patients harboring STAT3 mutation are particularly prone to airway remodeling and airway infections. OBJECTIVES: Airway epithelial cells play a central role as the first line of defense against pathogenic infection and express high levels of STAT3. This study thus interrogates how AD-HIES STAT3 mutations impact the physiological functions of airway epithelial cells. METHODS: This study created human airway basal cells expressing 4 common AD-HIES STAT3 mutants (R382W, V463del, V637M, and Y657S). In addition, primary airway epithelial cells were isolated from a patient with Job syndrome who was harboring a STAT3-S560del mutation and from mice harboring a STAT3-V463del mutation. Cell proliferation, differentiation, barrier function, bacterial elimination, and innate immune responses to pathogenic infection were quantitatively analyzed. RESULTS: STAT3 mutations reduce STAT3 protein phosphorylation, nuclear translocation, transcription activity, and protein stability in airway basal cells. As a consequence, STAT3-mutated airway basal cells give rise to airway epithelial cells with abnormal cellular composition and loss of coordinated mucociliary clearance. Notably, AD-HIES STAT3 airway epithelial cells are defective in bacterial killing and fail to initiate vigorous proinflammatory responses and neutrophil transepithelial migration in response to an experimental model of Pseudomonas aeruginosa infection. CONCLUSIONS: AD-HIES STAT3 mutations confer numerous abnormalities to airway epithelial cells in cell differentiation and host innate immunity, emphasizing their involvement in the pathogenesis of lung complications in Job syndrome. Therefore, therapies must address the epithelial defects as well as the previously noted immune cell defects to alleviate chronic infections in patients with Job syndrome.

Mucociliary transport deficiency and disease progression in Syrian hamsters with SARS-CoV-2 infection.

Substantial clinical evidence supports the notion that ciliary function in the airways is important in COVID-19 pathogenesis. Although ciliary damage has been observed in both in vitro and in vivo models, the extent or nature of impairment of mucociliary transport (MCT) in in vivo models remains unknown. We hypothesize that SARS-CoV-2 infection results in MCT deficiency in the airways of golden Syrian hamsters that precedes pathological injury in lung parenchyma. Micro-optical coherence tomography was used to quantitate functional changes in the MCT apparatus. Both genomic and subgenomic viral RNA pathological and physiological changes were monitored in parallel. We show that SARS-CoV-2 infection caused a 67% decrease in MCT rate as early as 2 days postinfection (dpi) in hamsters, principally due to 79% diminished airway coverage of motile cilia. Correlating quantitation of physiological, virological, and pathological changes reveals steadily descending infection from the upper airways to lower airways to lung parenchyma within 7 dpi. Our results indicate that functional deficits of the MCT apparatus are a key aspect of COVID-19 pathogenesis, may extend viral retention, and could pose a risk factor for secondary infection. Clinically, monitoring abnormal ciliated cell function may indicate disease progression. Therapies directed toward the MCT apparatus deserve further investigation.

Bendable long graded index lens microendoscopy.

Graded index (GRIN) lens endoscopy has broadly benefited biomedical microscopic imaging by enabling accessibility to sites not reachable by traditional benchtop microscopes. It is a long-held notion that GRIN lenses can only be used as rigid probes, which may limit their potential for certain applications. Here, we describe bendable and long-range GRIN microimaging probes for a variety of potential micro-endoscopic biomedical applications. Using a two-photon fluorescence imaging system, we have experimentally demonstrated the feasibility of three-dimensional imaging through a 500-µm-diameter and ∼11 cm long GRIN lens subject to a cantilever beam-like deflection with a minimum bend radius of ∼25 cm. Bend-induced perturbation to the field of view and resolution has also been investigated quantitatively. Our development alters the conventional notion of GRIN lenses and enables a range of innovative applications. For example, the demonstrated flexibility is highly desirable for implementation into current and emerging minimally invasive clinical procedures, including a pioneering microdevice for high-throughput cancer drug selection.

COVID-19 Causes Ciliary Dysfunction as Demonstrated by Human Intranasal Micro-Optical Coherence Tomography Imaging.

Severe acute respiratory syndrome coronavirus (SARS-CoV-2), causative agent of coronavirus disease 2019 (COVID-19), binds via ACE2 receptors, highly expressed in ciliated cells of the nasal epithelium. 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 epithelial anatomy, ciliary motion, and mucus transport. We hypothesized that respiratory epithelial cell dysfunction in COVID-19 will manifest as reduced ciliated cell function and mucociliary abnormalities, features readily visualized by µOCT. Symptomatic outpatients with SARS-CoV-2 aged ≥ 18 years were recruited within 14 days of symptom onset. Data was interpreted for subjects with COVID-19 (n=13) in comparison to healthy controls (n=8). Significant reduction in functional cilia, diminished ciliary beat frequency, and abnormal ciliary activity were evident. Other abnormalities included denuded epithelium, presence of mucus rafts, and increased inflammatory cells. Our results indicate that subjects with mild but symptomatic COVID-19 exhibit functional abnormalities of the respiratory mucosa underscoring the importance of mucociliary health in viral illness and disease transmission. Ciliary imaging enables investigation of early pathogenic mechanisms of COVID-19 and may be useful for evaluating disease progression and therapeutic response.