Characterization of primary rat nasal epithelial cultures in CFTR knockout rats as a model for CF sinus disease

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.

Effects of 101BHG-D01, a novel M receptor antagonism, on allergic rhinitis in animal models and its mechanism

Allergic rhinitis (AR) is a nasal mucosal disease with sneezing and nasal itching as the main symptoms. Although AR treatment continues to improve, there remains a lack of effective drugs. There are still controversies regarding whether anticholinergic drugs can effectively and safely relieve the symptoms of AR and reduce inflammation in the nasal mucosa. Here, we synthesized 101BHG-D01, which is a novel anticholinergic drug that mainly targets the M3 receptor and may reduce the adverse effects of other anticholinergic drugs on the heart. We evaluated the effects of 101BHG-D01 on AR and investigated the potential molecular mechanism of anticholinergic therapy for AR. We found that 101BHG-D01 effectively alleviated AR symptoms, reduced the infiltration of inflammatory cells and attenuated the expression of inflammatory factors (IL-4, IL-5, IL-13, etc.) in various AR animal models. In addition, 101BHG-D01 reduced the activation of mast cells and the release of histamine from rat peritoneal mesothelial cells (RPMCs) challenged by IgE. Moreover, 101BHG-D01 reduced the expression of MUC5AC in IL-13-challenged rat nasal epithelial cells (RNECs) and human nasal epithelial cells (HNEpCs). Furthermore, IL-13 stimulation significantly increased JAK1 and STAT6 phosphorylation, which was suppressed by 101BHG-D01. We demonstrated that 101BHG-D01 reduced mucus secretion and inflammatory cell infiltration in the nasal mucosa, which may occur through a reduction in activation of the JAK1-STAT6 signaling pathway, indicating that 101BHG-D01 is a potent and safe anticholinergic therapy for AR.

Immunohistochemical expression of estrogen receptor alpha in the maxillary sinus, pulp, and periodontal ligament of adjacent teeth in late pregnancy in rats

This study aimed to assess the histological changes in the maxillary sinus and its adjacent dental tissues as pulp and periodontal ligament during pregnancy and investigate the role of estrogen hormone in these changes through the detection of estrogen receptors in these tissues. Sixteen adult female rats were used and were allocated into two groups: control non-pregnant (n = 8) and pregnant (n = 8). They were sacrificed and their heads were prepared for histological and immunohistochemical examination for estrogen receptor alpha. Our results revealed that pregnant rats revealed inflammatory changes in the sinus as thick epithelial lining, loss of cilia, swollen goblet cells, intraepithelial and interstitial edema. The lamina propria demonstrated considerable infiltration of inflammatory cells, glandular hyperplasia with vacuolar degeneration, and vascular congestion. Periodontal ligament and pulp revealed hyperemia and vascular congestion. Immunohistochemical examination of estrogen receptor alpha in the maxillary sinus and adjacent dental tissues (Periodontal ligament and pulp) in pregnant rats revealed a significant increase in its expression in all examined tissues. In conclusion, there was an increase in expression of ERα in the sinus mucosa and dental tissues during pregnancy together with slight inflammatory changes in these tissues. Hence, dentists should be aware of the effect of these changes on the pregnant women avoiding teeth extraction due to misdiagnosis of dental, periodontal or sinus pain after exclusion of true pathologies.

Assessing the consistency of iPSC and animal models in cystic fibrosis modelling: A meta-analysis

INTRODUCTION

Cystic fibrosis (CF) is a hereditary autosomal recessive disorder caused by a range of mutations in the CF Transmembrane Conductance Regulator (CFTR) gene. This gene encodes the CFTR protein, which acts as a chloride channel activated by cyclic AMP (cAMP). This meta-analysis aimed to compare the responsiveness of induced pluripotent stem cells (iPSCs) to cAMP analogues to that of commonly used animal models.

METHODS

Databases searched included PubMed, Scopus, and Medline from inception to January 2020. A total of 8 and 3 studies, respectively, for animal models and iPSCs, were analyzed. Studies were extracted for investigating cAMP-stimulated anion transport by measuring the short circuit current (Isc) of chloride channels in different animal models and iPSC systems We utilized an inverse variance heterogeneity model for synthesis.

RESULTS

Our analysis showed considerable heterogeneity in the mean Isc value in both animal models and iPSCs studies (compared to their WT counterparts), and both suffer from variable responsiveness based on the nature of the underlying model. There was no clear advantage of one over the other.

CONCLUSIONS

Studies on both animal and iPSCs models generated considerable heterogeneity. Given the potential of iPSC-derived models to study different diseases, we recommend paying more attention to developing reproducible models of iPSC as it has potential if adequately developed.

The Microbiome and Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is persistent inflammation and/or infection of the nasal cavity and paranasal sinuses. Recent advancements in culture-independent molecular techniques have enhanced understanding of interactions between sinus microbiota and upper airway microenvironment. The dysbiosis hypothesis-alteration of microbiota associated with perturbation of the local ecological landscape-is suggested as a mechanism involved in CRS pathogenesis. This review discusses the complex role of the microbiota in health and in CRS and considerations in sinus microbiome investigation, dysbiosis of sinus microbiota in CRS, microbial interactions in CRS, and development of preclinical models. The authors conclude with future directions for CRS-associated microbiome research.

Characterization of two rat models of cystic fibrosis-KO and F508del CFTR-Generated by Crispr-Cas9

BACKGROUND

Genetically engineered animals are essential for gaining a proper understanding of the disease mechanisms of cystic fibrosis (CF). The rat is a relevant laboratory model for CF because of its zootechnical capacity, size, and airway characteristics, including the presence of submucosal glands.

METHODS

We describe the generation of a CF rat model (F508del) homozygous for the p.Phe508del mutation in the transmembrane conductance regulator (Cftr) gene. This model was compared to new Cftr -/- rats (CFTR KO). Target organs in CF were examined by histological staining of tissue sections and tooth enamel was quantified by micro-computed tomography. The activity of CFTR was evaluated by nasal potential difference (NPD) and short-circuit current measurements. The effect of VX-809 and VX-770 was analyzed on nasal epithelial primary cell cultures from F508del rats.

RESULTS

Both newborn F508del and Knock out (KO) animals developed intestinal obstruction that could be partly compensated by special diet combined with an osmotic laxative. The two rat models exhibited CF phenotypic anomalies such as vas deferens agenesis and tooth enamel defects. Histology of the intestine, pancreas, liver, and lungs was normal. Absence of CFTR function in KO rats was confirmed ex vivo by short-circuit current measurements on colon mucosae and in vivo by NPD, whereas residual CFTR activity was observed in F508del rats. Exposure of F508del CFTR nasal primary cultures to a combination of VX-809 and VX-770 improved CFTR-mediated Cl- transport.

CONCLUSIONS

The F508del rats reproduce the phenotypes observed in CFTR KO animals and represent a novel resource to advance the development of CF therapeutics.

Korean Red Ginseng aqueous extract improves markers of mucociliary clearance by stimulating chloride secretion

Background

Abnormal chloride (Cl^-) transport has a detrimental impact on mucociliary clearance in both cystic fibrosis (CF) and non-CF chronic rhinosinusitis. Ginseng is a medicinal plant noted to have anti-inflammatory and antimicrobial properties. The present study aims to assess the capability of red ginseng aqueous extract (RGAE) to promote transepithelial Cl^- secretion in nasal epithelium.

Methods

Primary murine nasal septal epithelial (MNSE) [wild-type (WT) and transgenic CFTR^-/-], fisher-rat-thyroid (FRT) cells expressing human WT CFTR, and TMEM16A-expressing human embryonic kidney cultures were utilized for the present experiments. Ciliary beat frequency (CBF) and airway surface liquid (ASL) depth measurements were performed using micro-optical coherence tomography (μOCT). Mechanisms underlying transepithelial Cl^- transport were determined using pharmacologic manipulation in Ussing chambers and whole-cell patch clamp analysis.

Results

RGAE (at 30μg/mL of ginsenosides) significantly increased Cl^- transport [measured as change in short-circuit current (ΔI_SC = μA/cm²)] when compared with control in WT and CFTR^-/- MNSE (WT vs control = 49.8±2.6 vs 0.1+/-0.2, CFTR^-/- = 33.5±1.5 vs 0.2±0.3, p < 0.0001). In FRT cells, the CFTR-mediated ΔI_SC attributed to RGAE was small (6.8 ± 2.5 vs control, 0.03 ± 0.01, p < 0.05). In patch clamp, TMEM16A-mediated currents were markedly improved with co-administration of RGAE and uridine 5-triphosphate (8406.3 +/- 807.7 pA) over uridine 5-triphosphate (3524.1 +/- 292.4 pA) or RGAE alone (465.2 +/- 90.7 pA) (p < 0.0001). ASL and CBF were significantly greater with RGAE (6.2+/-0.3 μm vs control, 3.9+/-0.09 μm; 10.4+/-0.3 Hz vs control, 7.3 ± 0.2 Hz; p < 0.0001) in MNSE.

Conclusion

RGAE augments ASL depth and CBF by stimulating Cl^- secretion through CaCC, which suggests therapeutic potential in both CF and non-CF chronic rhinosinusitis.

Animal Models in the Pathophysiology of Cystic Fibrosis

Our understanding of the multiorgan pathology of cystic fibrosis (CF) has improved impressively during the last decades, but we still lack a full comprehension of the disease progression. Animal models have greatly contributed to the elucidation of specific mechanisms involved in CF pathophysiology and the development of new therapies. Soon after the cloning of the CF transmembrane conductance regulator (CFTR) gene in 1989, the first mouse model was generated and this model has dominated in vivo CF research ever since. Nonetheless, the failure of murine models to mirror human disease severity in the pancreas and lung has led to the generation of larger animal models such as pigs and ferrets. The following review presents and discusses data from the current animal models used in CF research.

Seeing cilia: imaging modalities for ciliary motion and clinical connections

The respiratory tract is lined with multiciliated epithelial cells that function to move mucus and trapped particles via the mucociliary transport apparatus. Genetic and acquired ciliopathies result in diminished mucociliary clearance, contributing to disease pathogenesis. Recent innovations in imaging technology have advanced our understanding of ciliary motion in health and disease states. Application of imaging modalities including transmission electron microscopy, high-speed video microscopy, and micron-optical coherence tomography could improve diagnostics and be applied for precision medicine. In this review, we provide an overview of ciliary motion, imaging modalities, and ciliopathic diseases of the respiratory system including primary ciliary dyskinesia, cystic fibrosis, chronic obstructive pulmonary disease, and idiopathic pulmonary fibrosis.

Assessment of acquired mucociliary clearance defects using micro-optical coherence tomography

BACKGROUND

Dehydration of airway surface liquid (ASL) disrupts normal mucociliary clearance (MCC) in sinonasal epithelium, which may lead to chronic rhinosinusitis (CRS). Abnormal chloride (Cl^- ) transport is one such mechanism that contributes to this disorder and can be acquired secondary to environmental perturbations, such as hypoxia at the tissue surface. The objective of this study was to assess the technological feasibility of the novel micro-optical coherence tomography (μOCT) imaging technique for investigating acquired MCC defects in cultured human sinonasal epithelial (HSNE) cells.

METHODS

Primary HSNE cell cultures were subjected to a 1% oxygen environment for 12 hours to induce acquired cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. Ion transport characteristics were assessed with pharmacologic manipulation in Ussing chambers. ASL, periciliary fluid (PCL), and ciliary beat frequency (CBF) were evaluated using μOCT.

RESULTS

Amiloride-sensitive transport (ΔI_SC ) was greater in cultures exposed to hypoxia (hypoxia: -13.2 ± 0.6 μA/cm² ; control: -6.5 ± 0.1 μA/cm² ; p < 0.01), whereas CFTR-mediated anion transport was significantly diminished (hypoxia: 28.6 ± 0.3 μA/cm² ; control: 36.2 ± 1.6 μA/cm² ; p < 0.01), consistent with acquired CFTR dysfunction and sodium hyperabsorption. Hypoxia diminished all markers of airway surface function microanatomy as observed with μOCT, including ASL (hypoxia: 5.0 ± 0.4 μm; control: 9.0 ± 0.9 μm; p < 0.01) and PCL depth (hypoxia: 2.5 ± 0.1 μm; control: 4.8 ± 0.3 μm; p < 0.01), and CBF (hypoxia: 8.7 ± 0.3 Hz; control: 10.2 ± 0.3 Hz; p < 0.01).

CONCLUSION

Hypoxia-induced defects in epithelial anion transport in HSNE led to predictable effects on markers of MCC measured with novel μOCT imaging. This imaging method represents a technological leap forward and is feasible for assessing acquired defects impacting the airway surface.

Sinus hypoplasia in the cystic fibrosis rat resolves in the absence of chronic infection

BACKGROUND

Sinus hypoplasia is a hallmark characteristic in cystic fibrosis (CF). Chronic rhinosinusitis (CRS) is nearly universal from a young age, impaired sinus development could be secondary to loss of the cystic fibrosis transmembrane conductance regulator (CFTR) or consequences of chronic infection during maturation. The objective of this study was to assess sinus development relative to overall growth in a novel CF animal model.

METHODS

Sinus development was evaluated in CFTR^-/- and CFTR^+/+ rats at 3 stages of development: newborn; 3 weeks; and 16 weeks. Microcomputed tomography (microCT) scanning, cultures, and histology were performed. Three-dimensional sinus and skull volumes were quantified.

RESULTS

At birth, sinus volumes were decreased in CFTR^-/- rats compared with wild-type rats (mean ± SEM: 11.3 ± 0.85 mm³ vs 14.5 ± 0.73 mm³ ; p < 0.05), despite similar weights (8.4 ± 0.46 gm vs 8.3 ± 0.51 gm; p = 0.86). CF rat weights declined by 16 weeks (378.4 ± 10.6 gm vs 447.4 ± 15.9 gm; p < 0.05), sinus volume increased similar to wild-type rats (201.1 ± 3.77 gm vs 203.4 ± 7.13 gm; p = 0.8). The ratio of sinus volume to body weight indicates hypoplasia present at birth (1.37 ± 0.12 vs 1.78 ± 0.11; p < 0.05) and showed an increase compared with CFTR^+/+ animals by 16 weeks (0.53 ± 0.02 vs 0.46 ± 0.02; p < 0.05). Rats did not develop histologic evidence of chronic infection.

CONCLUSION

CF rat sinuses are smaller at birth, but develop volumes similar to wild-type rats with maturation. This suggests that loss of CFTR may confer sinus hypoplasia at birth, but normal development ensues without chronic sinus infection.