Airway disease phenotypes in animal models of cystic fibrosis

A new era of targeting cystic fibrosis with non-viral delivery of genomic medicines

Cystic fibrosis (CF) is a complex genetic respiratory disorder that necessitates innovative gene delivery strategies to address the mutations in the gene. This review delves into the promises and challenges of non-viral gene delivery for CF therapy and explores strategies to overcome these hurdles. Several emerging technologies and nucleic acid cargos for CF gene therapy are discussed. Novel formulation approaches including lipid and polymeric nanoparticles promise enhanced delivery through the CF mucus barrier, augmenting the potential of non-viral strategies. Additionally, safety considerations and regulatory perspectives play a crucial role in navigating the path toward clinical translation of gene therapy.

Acute exposure to realistic simulated urban atmospheres exacerbates pulmonary phenotype in cystic fibrosis-like mice

Cystic Fibrosis (CF) is a lethal genetic disorder caused by pathogenic mutations of the CFTR gene. CF patients show a high phenotypic variability of unknown origin. In this context, the present study was therefore dedicated to investigating the effects of acute exposure to air pollution on the pulmonary morbidity of a CF-like mice model. To achieve our aim, we developed a multidisciplinary approach and designed an innovative protocol using a simulation chamber reproducing multiphasic chemical processes at the laboratory. A particular attention was paid to modulate the composition of these simulated atmospheres, in terms of concentrations of gaseous and particulate pollutants. Exposure to simulated urban atmospheres induced mucus secretion and increased inflammatory biomarkers levels, oxidative stress as well as expression of lung remodeling actors in both WT and CF-like mice. The latter were more susceptible to develop such a response. Though we could not establish direct mechanistic link between biological responses and specific components, the type of immune response induced depended on the chemical composition of the atmospheres. Overall, we demonstrated that air pollution is an important determinant of CF-like lung phenotypic variability and emphasized the added value of considering air pollution with a multi-pollutant approach.

Combinatorial development of nebulized mRNA delivery formulations for the lungs

Inhaled delivery of mRNA has the potential to treat a wide variety of diseases. However, nebulized mRNA lipid nanoparticles (LNPs) face several unique challenges including stability during nebulization and penetration through both cellular and extracellular barriers. Here we develop a combinatorial approach addressing these barriers. First, we observe that LNP formulations can be stabilized to resist nebulization-induced aggregation by altering the nebulization buffer to increase the LNP charge during nebulization, and by the addition of a branched polymeric excipient. Next, we synthesize a combinatorial library of ionizable, degradable lipids using reductive amination, and evaluate their delivery potential using fully differentiated air-liquid interface cultured primary lung epithelial cells. The final combination of ionizable lipid, charge-stabilized formulation and stability-enhancing excipient yields a significant improvement in lung mRNA delivery over current state-of-the-art LNPs and polymeric nanoparticles.

Inhibition of mucus secretion by niclosamide and benzbromarone in airways and intestine

The Ca2+ activated Cl- channel TMEM16A (anoctamin 1; ANO1) is expressed in secretory epithelial cells of airways and intestine. Previous studies provided evidence for a role of ANO1 in mucus secretion. In the present study we investigated the effects of the two ANO1-inhibitors niclosamide (Niclo) and benzbromarone (Benz) in vitro and in vivo in mouse models for cystic fibrosis (CF) and asthma. In human CF airway epithelial cells (CFBE), Ca2+ increase and activation of ANO1 by adenosine triphosphate (ATP) or ionomycin was strongly inhibited by 200 nM Niclo and 1 µM Benz. In asthmatic mice airway mucus secretion was inhibited by intratracheal instillation of Niclo or Benz. In homozygous F508del-cftr mice, intestinal mucus secretion and infiltration by CD45-positive cells was inhibited by intraperitoneal injection of Niclo (13 mg/kg/day for 7 days). In homozygous F508del-cftr rats intestinal mucus secretion was inhibited by oral application of Benz (5 mg/kg/day for 60 days). Taken together, well tolerated therapeutic concentrations of niclosamide and benzbromarone corresponding to plasma levels of treated patients, inhibit ANO1 and intracellular Ca2+ signals and may therefore be useful in inhibiting mucus hypersecretion and mucus obstruction in airways and intestine of patients suffering from asthma and CF, respectively.

An ex vivo rat trachea model reveals abnormal airway physiology and a gland secretion defect in cystic fibrosis

Cystic fibrosis (CF) is a genetic disease hallmarked by aberrant ion transport that results in delayed mucus clearance, chronic infection, and progressive lung function decline. Several animal models have been developed to study the airway anatomy and mucus physiology in CF, but they are costly and difficult to maintain, making them less accessible for many applications. A more available CFTR-/- rat model has been developed and characterized to develop CF airway abnormalities, but consistent dosing of pharmacologic agents and longitudinal evaluation remain a challenge. In this study, we report the development and characterization of a novel ex vivo trachea model that utilizes both wild type (WT) and CFTR-/- rat tracheae cultured on a porcine gelatin matrix. Here we show that the ex vivo tracheae remain viable for weeks, maintain a CF disease phenotype that can be readily quantified, and respond to stimulation of mucus and fluid secretion by cholinergic stimulation. Furthermore, we show that ex vivo tracheae may be used for well-controlled pharmacological treatments, which are difficult to perform on freshly excised trachea or in vivo models with this degree of scrutiny. With improved interrogation possible with a durable trachea, we also established firm evidence of a gland secretion defect in CFTR-/- rat tracheae compared to WT controls. Finally, we demonstrate that the ex vivo tracheae can be used to generate high mucus protein yields for subsequent studies, which are currently limited by in vivo mucus collection techniques. Overall, this study suggests that the ex vivo trachea model is an effective, easy to set up culture model to study airway and mucus physiology.

Cigarette smoke-induced injury induces distinct sex-specific transcriptional signatures in mice tracheal epithelial cells

The airway epithelial barrier is crucial for defending against respiratory insults and diseases. Disruption of epithelial integrity contributes to respiratory diseases, and sex-specific differences in susceptibility and severity have been observed. However, sex-specific differences in the context of respiratory diseases are often overlooked, especially in murine models. In this study, we investigated the in vitro transcriptomics of male and female murine tracheal epithelial cells (mTECs) in response to chronic cigarette smoke (CS) exposure using an International Organization for Standardization (ISO) puff regimen. Our findings reveal sex-specific differences in the baseline characteristics of airway epithelial cells. Female mTECs demonstrated stronger barrier function and higher ciliary function compared with males. The barrier function was disrupted in both males and females following chronic CS, but the difference was more significant in females due to their higher baseline. Female mice exhibited transcriptional signatures suggesting dedifferentiation with increased basal cells and markers of cellular senescence. Pathway analysis indicated potential protective roles of planar cell polarity (PCP) in preventing dedifferentiation in male mice exposed to CS. We also observed sex-specific differences in the DNA damage response and antioxidant levels, suggesting distinct mechanisms underlying cellular stress. Understanding these sex-specific mechanisms could facilitate the development of targeted therapeutic strategies for lung diseases associated with environmental insults. Recognizing sex-based differences in disease susceptibility and treatment response can lead to personalized care and improved outcomes. Clinical trials should consider sex as a biological variable to develop effective interventions that address the unique differences between men and women in respiratory diseases.NEW & NOTEWORTHY The study underscores the importance of considering sex-specific differences in the airway epithelium in respiratory diseases such as COPD. Differences in gene expression between males and females at baseline and in response to chronic injury in the airway epithelium could have implications on disease susceptibility, both in COPD and other respiratory diseases. Therefore, understanding these differences is crucial for developing targeted therapies to treat respiratory diseases based on a sex-specific manner.

Pkhd1cyli/cyli mice have altered renal Pkhd1 mRNA processing and hormonally sensitive liver disease

Autosomal-recessive polycystic kidney disease (ARPKD; MIM #263200) is a severe, hereditary, hepato-renal fibrocystic disorder that causes early childhood morbidity and mortality. Mutations in the polycystic kidney and hepatic disease 1 (PKHD1) gene, which encodes the protein fibrocystin/polyductin complex (FPC), cause all typical forms of ARPKD. Several mouse lines carrying diverse, genetically engineered disruptions in the orthologous Pkhd1 gene have been generated, but none expresses the classic ARPKD renal phenotype. In the current study, we characterized a spontaneous mouse Pkhd1 mutation that is transmitted as a recessive trait and causes cysticliver (cyli), similar to the hepato-biliary disease in ARPKD, but which is exacerbated by age, sex, and parity. We mapped the mutation to Chromosome 1 and determined that an insertion/deletion mutation causes a frameshift within Pkhd1 exon 48, which is predicted to result in a premature termination codon (UGA). Pkhd1cyli/cyli (cyli) mice exhibit a severe liver pathology but lack renal disease. Further analysis revealed that several alternatively spliced Pkhd1 mRNA, all containing exon 48, were expressed in cyli kidneys, but in lower abundance than in wild-type kidneys, suggesting that these transcripts escaped from nonsense-mediated decay (NMD). We identified an AAAAAT motif in exon 48 upstream of the cyli mutation which could enable ribosomal frameshifting, thus potentially allowing production of sufficient amounts of FPC for renoprotection. This mechanism, expressed in a species-specific fashion, may help explain the disparities in the renal phenotype observed between Pkhd1 mutant mice and patients with PKHD1-related disease. KEY MESSAGES: The Pkhd1cyli/cyli mouse expresses cystic liver disease, but no kidney phenotype. Pkhd1 mRNA expression is decreased in cyli liver and kidneys compared to wild-type. Ribosomal frameshifting may be responsible for Pkhd1 mRNA escape from NMD. Pkhd1 mRNA escape from NMD could contribute to the absent kidney phenotype.

Druggable redox pathways against Mycobacterium abscessus in cystic fibrosis patient-derived airway organoids

Mycobacterium abscessus (Mabs) drives life-shortening mortality in cystic fibrosis (CF) patients, primarily because of its resistance to chemotherapeutic agents. To date, our knowledge on the host and bacterial determinants driving Mabs pathology in CF patient lung remains rudimentary. Here, we used human airway organoids (AOs) microinjected with smooth (S) or rough (R-)Mabs to evaluate bacteria fitness, host responses to infection, and new treatment efficacy. We show that S Mabs formed biofilm, and R Mabs formed cord serpentines and displayed a higher virulence. While Mabs infection triggers enhanced oxidative stress, pharmacological activation of antioxidant pathways resulted in better control of Mabs growth and reduced virulence. Genetic and pharmacological inhibition of the CFTR is associated with better growth and higher virulence of S and R Mabs. Finally, pharmacological activation of antioxidant pathways inhibited Mabs growth, at least in part through the quinone oxidoreductase NQO1, and improved efficacy in combination with cefoxitin, a first line antibiotic. In conclusion, we have established AOs as a suitable human system to decipher mechanisms of CF-driven respiratory infection by Mabs and propose boosting of the NRF2-NQO1 axis as a potential host-directed strategy to improve Mabs infection control.

Nicotine aerosols diminish airway CFTR function and mucociliary clearance

Electronic cigarettes (e-cigs) are often promoted as safe alternatives to smoking based on the faulty perception that inhaling nicotine is safe until other harmful chemicals in cigarette smoke are absent. Previously, others and we have reported that, similar to cigarette smoke, e-cig aerosols decrease CFTR-mediated ion transport across airway epithelium. However, it is unclear whether such defective epithelial ion transport by e-cig aerosols occurs in vivo and what the singular contribution of inhaled nicotine is to impairments in mucociliary clearance (MCC), the primary physiologic defense of the airways. Here, we tested the effects of nicotine aerosols from e-cigs in primary human bronchial epithelial (HBE) cells and two animal models, rats and ferrets, known for their increasing physiologic complexity and potential for clinical translation, followed by in vitro and in vivo electrophysiologic assays for CFTR activity and micro-optical coherence tomography (μOCT) image analyses for alterations in airway mucus physiology. Data presented in this report indicate nicotine in e-cig aerosols causes 1) reduced CFTR and epithelial Na+ channel (ENaC)-mediated ion transport, 2) delayed MCC, and 3) diminished airway surface hydration, as determined by periciliary liquid depth analysis. Interestingly, the common e-cig vehicles vegetable glycerin and propylene glycol did not affect CFTR function or MCC in vivo despite their significant adverse effects in vitro. Overall, our studies contribute to an improved understanding of inhaled nicotine effects on lung health among e-cig users and inform pathologic mechanisms involved in altered host defense and increased risk for tobacco-associated lung diseases.

In Vivo Inflammation Caused by Achromobacter spp. Cystic Fibrosis Clinical Isolates Exhibiting Different Pathogenic Characteristics

Achromobacter spp. lung infection in cystic fibrosis has been associated with inflammation, increased frequency of exacerbations, and decline of respiratory function. We aimed to evaluate in vivo the inflammatory effects of clinical isolates exhibiting different pathogenic characteristics. Eight clinical isolates were selected based on different pathogenic characteristics previously assessed: virulence in Galleria mellonella larvae, cytotoxicity in human bronchial epithelial cells, and biofilm formation. Acute lung infection was established by intratracheal instillation with 10.5 × 10⁸ bacterial cells in wild-type and CFTR-knockout (KO) mice expressing a luciferase gene under control of interleukin-8 promoter. Lung inflammation was monitored by in vivo bioluminescence imaging up to 48 h after infection, and mortality was recorded up to 96 h. Lung bacterial load was evaluated by CFU count. Virulent isolates caused higher lung inflammation and mice mortality, especially in KO animals. Isolates both virulent and cytotoxic showed higher persistence in mice lungs, while biofilm formation was not associated with lung inflammation, mice mortality, or bacterial persistence. A positive correlation between virulence and lung inflammation was observed. These results indicate that Achromobacter spp. pathogenic characteristics such as virulence and cytotoxicity may be associated with clinically relevant effects and highlight the importance of elucidating their mechanisms.

Inflammation as a Regulator of the Airway Surface Liquid pH in Cystic Fibrosis

The airway surface liquid (ASL) is a thin sheet of fluid that covers the luminal aspect of the airway epithelium. The ASL is a site of several first-line host defenses, and its composition is a key factor that determines respiratory fitness. Specifically, the acid-base balance of ASL has a major influence on the vital respiratory defense processes of mucociliary clearance and antimicrobial peptide activity against inhaled pathogens. In the inherited disorder cystic fibrosis (CF), loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function reduces HCO3- secretion, lowers the pH of ASL (pHASL), and impairs host defenses. These abnormalities initiate a pathologic process whose hallmarks are chronic infection, inflammation, mucus obstruction, and bronchiectasis. Inflammation is particularly relevant as it develops early in CF and persists despite highly effective CFTR modulator therapy. Recent studies show that inflammation may alter HCO3- and H+ secretion across the airway epithelia and thus regulate pHASL. Moreover, inflammation may enhance the restoration of CFTR channel function in CF epithelia exposed to clinically approved modulators. This review focuses on the complex relationships between acid-base secretion, airway inflammation, pHASL regulation, and therapeutic responses to CFTR modulators. These factors have important implications for defining optimal ways of tackling CF airway inflammation in the post-modulator era.

Distribution and Expression of Pulmonary Ionocyte-Related Factors CFTR, ATP6V0D2, and ATP6V1C2 in the Lungs of Yaks at Different Ages

In order to reveal the distribution and expression characteristics of the pulmonary ionocyte-related factors CFTR, ATP6V0D2, and ATP6V1C2 in the lungs of yaks of different ages. Explore the possible regulation of these pulmonary ionocyte-related factors in the yak lung for adaptation to high-altitude hypoxia. The localization and expression of CTFR, ATP6V0D2, and ATP6V1C2 in the lungs of newborn, juvenile, adult, and elderly yaks were studied using immunohistochemistry, quantitative reverse transcription PCR, and Western blotting. Immunohistochemistry showed that CFTR, ATP6V0D2 and ATP6V1C2 were mainly localized in the ciliated cells and club cells of the epithelial mucosal layer of the bronchus and its branches in the lungs. For the qRT-PCR, expression of CFTR, ATP6V0D2 and ATP6V1C2 in the yak lungs varied according to age. For Western blotting, CFTR expression in the newborn group was significantly higher than in the other three groups. ATP6V0D2 expression of the adult group was significantly higher. ATP6V1C2 expression was the highest in the juvenile group (p < 0.05). This study showed that ciliated cells and club cells were related to the pulmonary ionocytes in yaks. CFTR, ATP6V0D2, and ATP6V1C2 were related to adaptations of yak lungs to high altitude hypoxia, through prevention of airway damage.

To bead or not to bead: A review of Pseudomonas aeruginosa lung infection models for cystic fibrosis

Cystic fibrosis (CF) lung disease is characterised by recurring bacterial infections resulting in inflammation, lung damage and ultimately respiratory failure. Pseudomonas aeruginosa is considered one of the most important lung pathogens in those with cystic fibrosis. While multiple cystic fibrosis animal models have been developed, many fail to mirror the cystic fibrosis lung disease of humans, including the colonisation by opportunistic environmental pathogens. Delivering bacteria to the lungs of animals in different forms is a way to model cystic fibrosis bacterial lung infections and disease. This review presents an overview of previous models, and factors to consider when generating a new P. aeruginosa lung infection model. The future development and application of lung infection models that more accurately reflect human cystic fibrosis lung disease has the potential to assist in understanding the pathophysiology of cystic fibrosis lung disease and for developing treatments.

Localized Infections with P. aeruginosa Strains Defective in Zinc Uptake Reveal That Zebrafish Embryos Recapitulate Nutritional Immunity Responses of Higher Eukaryotes

The innate immune responses of mammals to microbial infections include strategies based on manipulating the local concentration of metals such as iron (Fe) and zinc (Zn), commonly described as nutritional immunity. To evaluate whether these strategies are also present in zebrafish embryos, we have conducted a series of heart cavity-localized infection experiments with Pseudomonas aeruginosa strains characterized by a different ability to acquire Zn. We have found that, 48 h after infection, the bacterial strains lacking critical components of the Zn importers ZnuABC and ZrmABCD have a reduced colonization capacity compared to the wild-type strain. This observation, together with the finding of a high level of expression of Zur-regulated genes, suggests the existence of antimicrobial mechanisms based on Zn sequestration. However, we have observed that strains lacking such Zn importers have a selective advantage over the wild-type strain in the early stages of infection. Analysis of the expression of the gene that encodes for a Zn efflux pump has revealed that at short times after infection, P. aeruginosa is exposed to high concentrations of Zn. At the same time, zebrafish respond to the infection by activating the expression of the Zn transporters Slc30a1 and Slc30a4, whose mammalian homologs mediate a redistribution of Zn in phagocytes aimed at intoxicating bacteria with a metal excess. These observations indicate that teleosts share similar nutritional immunity mechanisms with higher vertebrates, and confirm the usefulness of the zebrafish model for studying host-pathogen interactions.

Acute polymicrobial airway infections: analysis in cystic fibrosis mice

Cystic fibrosis (CF) is a genetic disorder affecting epithelial ion transport, which among other impacts results in defective mucociliary clearance and innate defenses in the respiratory tract. Consequently, people with CF experience lifelong infections of the respiratory mucosa that are chronic and polymicrobial in nature. Young children with CF are initially colonized by opportunists like nontypeable Haemophilus influenzae (NTHi), which normally resides within the microbiome of the nasopharynx and upper airways and can also cause infections of the respiratory mucosa that include bronchitis and otitis media. NTHi is typically supplanted by other microbes as patients age; for example, people with CF are often chronically infected with mucoid strains of Pseudomonas aeruginosa, which prior work in our laboratory has shown to promote colonization and persistence by other opportunists that include Stenotrophomonas maltophilia. Our previous work has shown that polymicrobial infection impacts host colonization and persistence of incoming microbes via diverse mechanisms that include priming of host immunity that can promote microbial clearance, and cooperativity within polymicrobial biofilms, which can promote persistence. In infection studies with BALB/c Cftr^tm1UNC mice, results showed, as previously observed for WT BALB/c mice, preceding infection with NTHi decreased colonization and persistence by P. aeruginosa. Likewise, polymicrobial infection of BALB/c Cftr^tm1UNC and C57BL/6 Cftr^tm1UncTg(FABPhCFTR)1Jaw/J mice showed correlation between S. maltophilia and P. aeruginosa, with increased bacterial colonization and lung pathology. Based on these results, we conclude that our previous observations regarding polymicrobial infections with CF opportunists in WT mice are also validated using CF mice.

β-sitosterol inhibits trimethylamine production by regulating the gut microbiota and attenuates atherosclerosis in ApoE-/- mice

The intestinal microbial metabolite trimethylamine (TMA), which is activated by flavin monooxygenase (FMO) to produce trimethylamine-N-oxide (TMAO), has been implicated in the pathogenesis of atherosclerosis (AS), leading to the development of therapeutic strategies for AS. This study aimed to investigate whether β-sitosterol can inhibit TMA production in ApoE^-/- mice by reshaping the gut microbial structure. 16S rRNA sequencing of the gut microbiota showed that β-sitosterol has beneficial effects on intestinal flora function, especially the inhibition of bacteria genera that contain the gene cholintrimethylamine lyase, which is responsible for the major pathway for TMA production. In parallel, β-sitosterol effectively reduced the TMA, FMO3, and TMAO levels while ameliorating the atherosclerotic plaques of AS mice. Moreover, β-sitosterol could alleviate cholesterol metabolism and the inflammatory response, and improve the antioxidant defense capacity. These studies offer new insights into the mechanisms responsible for the antiatherosclerotic effects of β-sitosterol, which targets the microbiota-metabolism-immunity axis as a possible therapy for AS.

Production of CFTR Mutant Gene Model by Homologous Recombination System

OBJECTIVE

The most common mutation in cystic fibrosis (CF), (ΔF508-CFTR), results in impaired protein maturation, folding and transportation to the surface of the cell. As a consequence of impaired protein maturation and/or transport from the extracellular matrix to the cell, different systems are influenced, including gastrointestinal system and glandular system, reproductive system and respiratory systems. CF models are essential tools to provide further knowledge of CF pathophysiology. With this aim, we designed a transgenic CF model based on the homologous recombination (HR) system.

MATERIALS AND METHODS

In this experimental study, a specifically designed construct containing the CFTR gene with F508del was cloned into a PTZ57R cloning vector and then the construct was transformed into the male pronucleus by microinjection after in vitro fertilization (IVF). Then the rates of blastocyst formation and embryonic development at 72 hours after IVF, were evaluated using the inverted microscope and the insertion of the construct was approved by polymerase chain reaction (PCR) method.

RESULTS

The CFTR gene was successfully cloned into the PTZ57R cloning vector and overall, from 22 injected cells, 5 blastocysts were observed after pronuclear injection of the CFTR gene construct. PCR verification of the blastocyst with CFTR-specific primers represented complete recombination of CFTR into the mouse genome.

CONCLUSION

For the first time we designed a unique genome construction that can be detected using a simple PCR method. The pronuclear injection was performed for the transformation of the genome construct into the male pronuclei using microinjection and the development of zygote to the blastocyst stage has been observed following transgenesis.

Engineering Lipid Nanoparticles for Enhanced Intracellular Delivery of mRNA through Inhalation

Despite lipid nanoparticles' (LNPs) success in the effective and safe delivery of mRNA vaccines, an inhalation-based mRNA therapy for lung diseases remains challenging. LNPs tend to disintegrate due to shear stress during aerosolization, leading to ineffective delivery. Therefore, LNPs need to remain stable through the process of nebulization and mucus penetration, yet labile enough for endosomal escape. To meet these opposing needs, we utilized PEG lipid to enhance the surficial stability of LNPs with the inclusion of a cholesterol analog, β-sitosterol, to improve endosomal escape. Increased PEG concentrations in LNPs enhanced the shear resistance and mucus penetration, while β-sitosterol provided LNPs with a polyhedral shape, facilitating endosomal escape. The optimized LNPs exhibited a uniform particle distribution, a polyhedral morphology, and a rapid mucosal diffusion with enhanced gene transfection. Inhaled LNPs led to localized protein production in the mouse lung without pulmonary or systemic toxicity. Repeated administration of these LNPs led to sustained protein production in the lungs. Lastly, mRNA encoding the cystic fibrosis transmembrane conductance regulator (CFTR) was delivered after nebulization to a CFTR-deficient animal model, resulting in the pulmonary expression of this therapeutic protein. This study demonstrated the rational design approach for clinical translation of inhalable LNP-based mRNA therapies.

Development of liquid culture media mimicking the conditions of sinuses and lungs in cystic fibrosis and health

The respiratory tract is a compartmentalised and heterogenous environment. The nasopharynx and sinuses of the upper airways have distinct properties from the lungs and these differences may shape bacterial adaptation and evolution. Upper airway niches act as early colonisation sites for respiratory bacterial pathogens, including those, such as Pseudomonas aeruginosa, that can go on to establish chronic infection of the lungs in people with cystic fibrosis (CF). Despite the importance of upper airway environments in facilitating early adaptation to host environments, currently available in vitro models for study of respiratory infection in CF focus exclusively on the lungs. Furthermore, animal models, widely used to bridge the gap between in vitro systems and the clinical scenario, do not allow the upper and lower airways to be studied in isolation. We have developed a suite of culture media reproducing key features of the upper and lower airways, for the study of bacterial adaptation and evolution in different respiratory environments. For both upper and lower airway-mimicking media, we have developed formulations that reflect airway conditions in health and those that reflect the altered environment of the CF respiratory tract. Here, we describe the development and validation of these media and their use for study of genetic and phenotypic adaptations in P. aeruginosa during growth under upper or lower airway conditions in health and in CF.

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.

Inhaled gene therapy of preclinical muco-obstructive lung diseases by nanoparticles capable of breaching the airway mucus barrier

INTRODUCTION

Inhaled gene therapy of muco-obstructive lung diseases requires a strategy to achieve therapeutically relevant gene transfer to airway epithelium covered by particularly dehydrated and condensed mucus gel layer. Here, we introduce a synthetic DNA-loaded mucus-penetrating particle (DNA-MPP) capable of providing safe, widespread and robust transgene expression in in vivo and in vitro models of muco-obstructive lung diseases.

METHODS

We investigated the ability of DNA-MPP to mediate reporter and/or therapeutic transgene expression in lung airways of a transgenic mouse model of muco-obstructive lung diseases (ie, Scnn1b-Tg) and in air-liquid interface cultures of primary human bronchial epithelial cells harvested from an individual with cystic fibrosis. A plasmid designed to silence epithelial sodium channel (ENaC) hyperactivity, which causes airway surface dehydration and mucus stasis, was intratracheally administered via DNA-MPP to evaluate therapeutic effects in vivo with or without pretreatment with hypertonic saline, a clinically used mucus-rehydrating agent.

RESULTS

DNA-MPP exhibited marked greater reporter transgene expression compared with a mucus-impermeable formulation in in vivo and in vitro models of muco-obstructive lung diseases. DNA-MPP carrying ENaC-silencing plasmids provided efficient downregulation of ENaC and reduction of mucus burden in the lungs of Scnn1b-Tg mice, and synergistic impacts on both gene transfer efficacy and therapeutic effects were achieved when DNA-MPP was adjuvanted with hypertonic saline.

DISCUSSION

DNA-MPP constitutes one of the rare gene delivery systems providing therapeutically meaningful gene transfer efficacy in highly relevant in vivo and in vitro models of muco-obstructive lung diseases due to its unique ability to efficiently penetrate airway mucus.

Mucociliary Transit Assessment Using Automatic Tracking in Phase Contrast X-Ray Images of Live Mouse Nasal Airways

Purpose

The rate of mucociliary transit (MCT) is an indicator of the hydration and health of the airways for cystic fibrosis (CF). To determine the effectiveness of cystic fibrosis respiratory therapies, we have developed a novel method to non-invasively quantify the local rate and patterns of MCT behaviour in vivo by using synchrotron phase contrast X-ray imaging (PCXI) to visualise the MCT motion of micron-sized spherical particles deposited onto the airway surfaces of live mice.

Methods

In this study the baseline MCT behaviour was assessed in the nasal airways of CFTR-null and normal mice which were then treated with hypertonic saline (HS) or mannitol. To assess MCT, the particle motion was tracked throughout the synchrotron PCXI sequences using fully-automated custom image analysis software.

Results

There was no significant difference in the MCT rate between normal and CFTR-null mice, but the analysis of MCT particle tracking showed that HS may have a longer duration of action in CFTR-null mice than in the normal mice.

Conclusion

This study demonstrated that changes in MCT rate in CF and normal mouse nasal airways can be measured using PCXI and customised tracking software and used for assessing the effects of airway rehydrating pharmaceutical treatments.

Influence of SARS-CoV-2 on airway mucus production: A review and proposed model

Coronavirus disease 2019 (COVID-19) is a worldwide pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has affected millions of lives. Individuals who survive severe COVID-19 can experience sustained respiratory symptoms that persist for months after initial infection. In other airway diseases, abnormal airway mucus contributes to sustained airway symptoms. However, the impact of SARS-CoV-2 on airway mucus has received limited attention. In the current review, we assess literature describing the impact of SARS-CoV-2 on airway pathophysiology with specific emphasis on mucus production. Accumulating evidence suggests that the 2 major secreted airway mucin glycoproteins, MUC5AC and MUC5B, are abnormal in some patients with COVID-19. Aberrations in MUC5AC or MUC5B in response to SARS-CoV-2 infection are likely due to inflammation, though the responsible mechanisms have yet to be determined. Thus, we also provide a proposed model highlighting mechanisms that can contribute to acute and sustained mucus abnormalities in SARS-CoV-2, with an emphasis on inflammatory cells and mediators, including mast cells and histamine. Last, we bring to light the challenges of studying abnormal mucus production in SARS-CoV-2 infections and discuss the strengths and limitations of model systems commonly used to study COVID-19. The evidence to date suggests that ferrets, nonhuman primates, and cats may have advantages over other models to investigate mucus in COVID-19.

Effective viral-mediated lung gene therapy: is airway surface preparation necessary?

Gene-based therapeutics are actively being pursued for the treatment of lung diseases. While promising advances have been made over the last decades, the absence of clinically available lung-directed genetic therapies highlights the difficulties associated with this effort. Largely, progress has been hindered by the presence of inherent physical and physiological airway barriers that significantly reduce the efficacy of gene transfer. These barriers include surface mucus, mucociliary action, cell-to-cell tight junctions, and the basolateral cell membrane location of viral receptors for many commonly used gene vectors. Accordingly, airway surface preparation methods have been developed to disrupt these barriers, creating a more conducive environment for gene uptake into the target airway cells. The two major approaches have been chemical and physical methods. Both have proven effective for increasing viral-mediated gene transfer pre-clinically, although with variable effect depending on the specific strategy employed. While such methods have been explored extensively in experimental settings, they have not been used clinically. This review covers the airway surface preparation strategies reported in the literature, the advantages and disadvantages of each method, as well as a discussion about applying this concept in the clinic.

Biomechanical, histological, and molecular characterization of a new posttraumatic model of arthrofibrosis in rats

Experimental analyses of posttraumatic knee arthrofibrosis utilize a rabbit model as a gold standard. However, a rodent model of arthrofibrosis offers many advantages including reduced cost and comparison with other models of organ fibrosis. This study aimed to characterize the biomechanical, histological, and molecular features of a novel posttraumatic model of arthrofibrosis in rats. Forty eight rats were divided into two equal groups. An immobilization procedure was performed on the right hind limbs of experimental rats. One group was immobilized for 4 weeks and the other for 8 weeks. Both groups were remobilized for 4 weeks. Limbs were studied biomechanically via assessment of torque versus degree of extension, histologically via whole knee specimen, and molecularly via gene expression of posterior capsular tissues. Significant differences were observed between experimental and control limbs at 4 N-cm of torque in the 4-week (knee extension: 115° ± 8° vs. 169° ± 17°, respectively; p = 0.007) and 8-week immobilization groups (knee extension: 99° ± 12° vs. 174° ± 9°, respectively; p = 0.008). Histologically, in each group experimental limbs demonstrated increased posterior capsular thickness and total area of tissue when compared to control limbs (p < 0.05). Gene expression values evaluated in each group were comparable. This study presents a novel rat model of arthrofibrosis with severe and persistent knee contractures demonstrated biomechanically and histologically. Statement of clinical significance: Arthrofibrosis is a common complication following contemporary total knee arthroplasties. The proposed model is reproducible, cost-effective, and can be employed for translational investigations studying the pathogenesis of arthrofibrosis and efficacy of neoadjuvant pharmacologic agents.

Development of liquid culture media mimicking the conditions of sinuses and lungs in cystic fibrosis and health

The respiratory tract is a compartmentalised and heterogenous environment. The nasopharynx and sinuses of the upper airways have distinct properties from the lungs and these differences may shape bacterial adaptation and evolution. Upper airway niches act as early colonisation sites for respiratory bacterial pathogens, including those, such as Pseudomonas aeruginosa, that can go on to establish chronic infection of the lungs in people with cystic fibrosis (CF). Despite the importance of upper airway environments in facilitating early adaptation to host environments, currently available in vitro models for study of respiratory infection in CF focus exclusively on the lungs. Furthermore, animal models, widely used to bridge the gap between in vitro systems and the clinical scenario, do not allow the upper and lower airways to be studied in isolation. We have developed a suite of culture media reproducing key features of the upper and lower airways, for the study of bacterial adaptation and evolution in different respiratory environments. For both upper and lower airway-mimicking media, we have developed formulations that reflect airway conditions in health and those that reflect the altered environment of the CF respiratory tract. Here, we describe the development and validation of these media and their use for study of genetic and phenotypic adaptations in P. aeruginosa during growth under upper or lower airway conditions in health and in CF.

Three-Dimensional Airway Spheroids and Organoids for Cystic Fibrosis Research

Cystic fibrosis (CF) is an autosomal recessive multi-organ disease caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, with morbidity and mortality primacy related to the lung disease. The CFTR protein, a chloride/bicarbonate channel, is expressed at the apical side of airway epithelial cells and is mainly involved in appropriate ion and fluid transport across the epithelium. Although many animal and cellular models have been developed to study the pathophysiological consequences of the lack/dysfunction of CFTR, only the three-dimensional (3D) structures termed “spheroids” and “organoids” can enable the reconstruction of airway mucosa to model organ development, disease pathophysiology, and drug screening. Airway spheroids and organoids can be derived from different sources, including adult lungs and induced pluripotent stem cells (iPSCs), each with its advantages and limits. Here, we review the major features of airway spheroids and organoids, anticipating that their potential in the CF field has not been fully shown. Further work is mandatory to understand whether they can accomplish better outcomes than other culture conditions of airway epithelial cells for CF personalized therapies and tissue engineering aims.

A review of cystic fibrosis: Basic and clinical aspects

Cystic fibrosis is an autosomal recessive disease caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). Here we summarize, at the basic descriptive level, clinical and genetic characteristics of cystic fibrosis gene mutations, while emphasizing differences between CF mutations found in Chinese pediatric CF patients compared to those found in Caucasian CF patients. In addition, we describe animal models used to study human cystic fibrosis disease and highlight unique features of each model that mimic specific human CF-associated signs and symptoms. At the clinical level, we summarize CF clinical manifestations and diagnostic, treatment, and prognostic methods to provide clinicians with information toward reducing CF misdiagnosis and missed diagnosis rates.

Human molecular genetics and the long road to treating cystic fibrosis

The causative gene in cystic fibrosis was identified in 1989, three years before the publication of the first issue of Human Molecular Genetics. CFTR was among the first genes underlying a common inherited disorder to be cloned, and hence its subsequent utilization towards a cure for CF provides a roadmap for other monogenic diseases. Over the past 30 years the advances that built upon knowledge of the gene and the CFTR protein to develop effective therapeutics have been remarkable, and yet the setbacks have also been challenging. Technological progress in other fields has often circumvented the barriers. This review focuses on key aspects of CF diagnostics and current approaches to develop new therapies for all CFTR mutations. It also highlights the major research advances that underpinned progress towards treatments, and considers the remaining obstacles.

Cystic Fibrosis Human Organs-on-a-Chip

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene: the gene product responsible for transporting chloride and bicarbonate ions through the apical membrane of most epithelial cells. Major clinical features of CF include respiratory failure, pancreatic exocrine insufficiency, and intestinal disease. Many CF animal models have been generated, but some models fail to fully capture the phenotypic manifestations of human CF disease. Other models that better capture the key characteristics of the human CF phenotype are cost prohibitive or require special care to maintain. Important differences have been reported between the pathophysiology seen in human CF patients and in animal models. These limitations present significant limitations to translational research. This review outlines the study of CF using patient-derived organs-on-a-chip to overcome some of these limitations. Recently developed microfluidic-based organs-on-a-chip provide a human experimental model that allows researchers to manipulate environmental factors and mimic in vivo conditions. These chips may be scaled to support pharmaceutical studies and may also be used to study organ systems and human disease. The use of these chips in CF discovery science enables researchers to avoid the barriers inherent in animal models and promote the advancement of personalized medicine.

Single-Dose Lentiviral Mediated Gene Therapy Recovers CFTR Function in Cystic Fibrosis Knockout Rats

Cystic fibrosis (CF) is a genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in defective ion transport in the airways. Addition of a functioning CFTR gene into affected airway cells has the potential to be an effective treatment for lung disease. The therapeutic efficacy of airway gene transfer can be quantified in animal models by assessing ion transport in the treated nasal epithelium using the nasal potential difference (PD) measurement technique. The nasal PD technique is routinely used in CF mice, however when applied to a recently developed CF rat model those animals did not tolerate the initial nasal PD assessment, therefore the procedure was firstly optimised in rats. This study evaluated the effect of lentiviral (LV)-mediated CFTR airway gene delivery on nasal PD in a CFTR knockout rat model. LV gene vector containing the CFTR gene tagged with a V5 epitope tag (LV-V5-CFTR) was delivered to the nasal epithelium of CF rats, and one week later nasal PD was analysed. This study demonstrated for the first time that LV-V5-CFTR treatment produced a mean correction of 46% towards wild-type chloride response in treated CF rats. Transduced cells were subsequently identifiable using V5 immunohistochemical staining. These findings in the nose validate the use of airway gene therapy for future lung based experiments.

The Ferret as a Model System for Neocortex Development and Evolution

The neocortex is the largest part of the cerebral cortex and a key structure involved in human behavior and cognition. Comparison of neocortex development across mammals reveals that the proliferative capacity of neural stem and progenitor cells and the length of the neurogenic period are essential for regulating neocortex size and complexity, which in turn are thought to be instrumental for the increased cognitive abilities in humans. The domesticated ferret, Mustela putorius furo, is an important animal model in neurodevelopment for its complex postnatal cortical folding, its long period of forebrain development and its accessibility to genetic manipulation in vivo. Here, we discuss the molecular, cellular, and histological features that make this small gyrencephalic carnivore a suitable animal model to study the physiological and pathological mechanisms for the development of an expanded neocortex. We particularly focus on the mechanisms of neural stem cell proliferation, neuronal differentiation, cortical folding, visual system development, and neurodevelopmental pathologies. We further discuss the technological advances that have enabled the genetic manipulation of the ferret in vivo. Finally, we compare the features of neocortex development in the ferret with those of other model organisms.

On the Corner of Models and Cure: Gene Editing in Cystic Fibrosis

Cystic fibrosis (CF) is a severe genetic disease for which curative treatment is still lacking. Next generation biotechnologies and more efficient cell-based and in vivo disease models are accelerating the development of novel therapies for CF. Gene editing tools, like CRISPR-based systems, can be used to make targeted modifications in the genome, allowing to correct mutations directly in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. Alternatively, with these tools more relevant disease models can be generated, which in turn will be invaluable to evaluate novel gene editing-based therapies for CF. This critical review offers a comprehensive description of currently available tools for genome editing, and the cell and animal models which are available to evaluate them. Next, we will give an extensive overview of proof-of-concept applications of gene editing in the field of CF. Finally, we will touch upon the challenges that need to be addressed before these proof-of-concept studies can be translated towards a therapy for people with CF.

Engineering Tissue-Informed Biomaterials to Advance Pulmonary Regenerative Medicine

Biomaterials intentionally designed to support the expansion, differentiation, and three-dimensional (3D) culture of induced-pluripotent stem cells (iPSCs) may pave the way to cell-based therapies for chronic respiratory diseases. These conditions are endured by millions of people worldwide and represent a significant cause of morbidity and mortality. Currently, there are no effective treatments for the majority of advanced lung diseases and lung transplantation remains the only hope for many chronically ill patients. Key opinion leaders speculate that the novel coronavirus, COVID-19, may lead to long-term lung damage, further exacerbating the need for regenerative therapies. New strategies for regenerative cell-based therapies harness the differentiation capability of human iPSCs for studying pulmonary disease pathogenesis and treatment. Excitingly, biomaterials are a cell culture platform that can be precisely designed to direct stem cell differentiation. Here, we present a closer look at the state-of-the-art of iPSC differentiation for pulmonary engineering, offer evidence supporting the power of biomaterials to improve stem cell differentiation, and discuss our perspective on the potential for tissue-informed biomaterials to transform pulmonary regenerative medicine.

Understanding Pseudomonas aeruginosa-Host Interactions: The Ongoing Quest for an Efficacious Vaccine

Pseudomonas aeruginosa is a leading cause of chronic respiratory infections in people with cystic fibrosis (CF), bronchiectasis or chronic obstructive pulmonary disease (COPD), and acute infections in immunocompromised individuals. The adaptability of this opportunistic pathogen has hampered the development of antimicrobial therapies, and consequently, it remains a major threat to public health. Due to its antimicrobial resistance, vaccines represent an alternative strategy to tackle the pathogen, yet despite over 50 years of research on anti-Pseudomonas vaccines, no vaccine has been licensed. Nevertheless, there have been many advances in this field, including a better understanding of the host immune response and the biology of P. aeruginosa. Multiple antigens and adjuvants have been investigated with varying results. Although the most effective protective response remains to be established, it is clear that a polarised Th2 response is sub-optimal, and a mixed Th1/Th2 or Th1/Th17 response appears beneficial. This comprehensive review collates the current understanding of the complexities of P. aeruginosa-host interactions and its implication in vaccine design, with a view to understanding the current state of Pseudomonal vaccine development and the direction of future efforts. It highlights the importance of the incorporation of appropriate adjuvants to the protective antigen to yield optimal protection.

Rescue from Pseudomonas aeruginosa Airway Infection via Stem Cell Transplantation

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which lead to impaired ion transport in epithelial cells. Although lung failure due to chronic infection is the major comorbidity in individuals with cystic fibrosis, the role of CFTR in non-epithelial cells has not been definitively resolved. Given the important role of host defense cells, we evaluated the Cftr deficiency in pulmonary immune cells by hematopoietic stem cell transplantation in cystic fibrosis mice. We transplanted healthy bone marrow stem cells and could reveal a stable chimerism of wild-type cells in peripheral blood. The outcome of stem cell transplantation and the impact of healthy immune cells were evaluated in acute Pseudomonas aeruginosa airway infection. In this study, mice transplanted with wild-type cells displayed better survival, lower lung bacterial numbers, and a milder disease course. This improved physiology of infected mice correlated with successful intrapulmonary engraftment of graft-derived alveolar macrophages, as seen by immunofluorescence microscopy and flow cytometry of graft-specific leucocyte surface marker CD45 and macrophage marker CD68. Given the beneficial effect of hematopoietic stem cell transplantation and stable engraftment of monocyte-derived CD68-positive macrophages, we conclude that replacement of mutant Cftr macrophages attenuates airway infection in cystic fibrosis mice.

Recombinant Acid Ceramidase Reduces Inflammation and Infection in Cystic Fibrosis

Rationale: In cystic fibrosis the major cause of morbidity and mortality is lung disease characterized by inflammation and infection. The influence of sphingolipid metabolism is poorly understood with a lack of studies using human airway model systems.Objectives: To investigate sphingolipid metabolism in cystic fibrosis and the effects of treatment with recombinant human acid ceramidase on inflammation and infection.Methods: Sphingolipids were measured using mass spectrometry in fully differentiated cultures of primary human airway epithelial cells and cocultures with Pseudomonas aeruginosa. In situ activity assays, Western blotting, and quantitative PCR were used to investigate function and expression of ceramidase and sphingomyelinase. Effects of treatment with recombinant human acid ceramidase on sphingolipid profile and inflammatory mediator production were assessed in cell cultures and murine models.Measurements and Main Results: Ceramide is increased in cystic fibrosis airway epithelium owing to differential function of enzymes regulating sphingolipid metabolism. Sphingosine, a metabolite of ceramide with antimicrobial properties, is not upregulated in response to P. aeruginosa by cystic fibrosis airway epithelia. Tumor necrosis factor receptor 1 is increased in cystic fibrosis epithelia and activates NF-κB signaling, generating inflammation. Treatment with recombinant human acid ceramidase, to decrease ceramide, reduced both inflammatory mediator production and susceptibility to infection.Conclusions: Sphingolipid metabolism is altered in airway epithelial cells cultured from people with cystic fibrosis. Treatment with recombinant acid ceramidase ameliorates the two pivotal features of cystic fibrosis lung disease, inflammation and infection, and thus represents a therapeutic approach worthy of further exploration.

The Microbiome in Cystic Fibrosis Pulmonary Disease

Cystic fibrosis (CF) is a genetic disease with mutational changes leading to profound dysbiosis, both pulmonary and intestinal, from a very young age. This dysbiosis plays an important role in clinical manifestations, particularly in the lungs, affected by chronic infection. The range of microbiological tools has recently been enriched by metagenomics based on next-generation sequencing (NGS). Currently applied essentially in a gene-targeted manner, metagenomics has enabled very exhaustive description of bacterial communities in the CF lung niche and, to a lesser extent, the fungi. Aided by progress in bioinformatics, this now makes it possible to envisage shotgun sequencing and opens the door to other areas of the microbial world, the virome, and the archaeome, for which almost everything remains to be described in cystic fibrosis. Paradoxically, applying NGS in microbiology has seen a rebirth of bacterial culture, but in an extended manner (culturomics), which has proved to be a perfectly complementary approach to NGS. Animal models have also proved indispensable for validating microbiome pathophysiological hypotheses. Description of pathological microbiomes and correlation with clinical status and therapeutics (antibiotic therapy, cystic fibrosis transmembrane conductance regulator (CFTR) modulators) revealed the richness of microbiome data, enabling description of predictive and follow-up biomarkers. Although monogenic, CF is a multifactorial disease, and both genotype and microbiome profiles are crucial interconnected factors in disease progression. Microbiome-genome interactions are thus important to decipher.

Chloride channels regulate differentiation and barrier functions of the mammalian airway

The conducting airway forms a protective mucosal barrier and is the primary target of airway disorders. The molecular events required for the formation and function of the airway mucosal barrier, as well as the mechanisms by which barrier dysfunction leads to early onset airway diseases, remain unclear. In this study, we systematically characterized the developmental landscape of the mouse airway using single-cell RNA sequencing and identified remarkably conserved cellular programs operating during human fetal development. We demonstrated that in mouse, genetic inactivation of chloride channel Ano1/Tmem16a compromises airway barrier function, results in early signs of inflammation, and alters the airway cellular landscape by depleting epithelial progenitors. Mouse Ano1-/-mutants exhibited mucus obstruction and abnormal mucociliary clearance that resemble the airway defects associated with cystic fibrosis. The data reveal critical and non-redundant roles for Ano1 in organogenesis, and show that chloride channels are essential for mammalian airway formation and function.

Progress in Model Systems of Cystic Fibrosis Mucosal Inflammation to Understand Aberrant Neutrophil Activity

In response to recurrent infection in cystic fibrosis (CF), powerful innate immune signals trigger polymorphonuclear neutrophil recruitment into the airway lumen. Exaggerated neutrophil proteolytic activity results in sustained inflammation and scarring of the airways. Consequently, neutrophils and their secretions are reliable clinical biomarkers of lung disease progression. As neutrophils are required to clear infection and yet a direct cause of airway damage, modulating adverse neutrophil activity while preserving their pathogen fighting function remains a key area of CF research. The factors that drive their pathological behavior are still under investigation, especially in early disease when aberrant neutrophil behavior first becomes evident. Here we examine the latest findings of neutrophils in pediatric CF lung disease and proposed mechanisms of their pathogenicity. Highlighted in this review are current and emerging experimental methods for assessing CF mucosal immunity and human neutrophil function in the laboratory.

Mucoviscidosis: fisiopatología, genética, aspectos clínicos y terapéuticos

La mucoviscidosis es la enfermedad autosómica recesiva grave más frecuente que afecta a la población caucásica. En Francia, por ejemplo, la incidencia es de un caso por cada 4.500 nacimientos. Esta enfermedad se debe a mutaciones en el gen CFTR (cystic fibrosis transmembrane conductance regulator, regulador de conductancia transmembrana de la fibrosis quística), situado en el brazo largo del cromosoma 7, que codifica una proteína transmembrana implicada en la regulación del transporte transepitelial de iones cloruro (Cl–). En Francia, la mutación más frecuente (alrededor del 80% de los casos) es la deleción del aminoácido 508 (fenilalanina), denominada F508del. La ausencia o la disfunción de la proteína CFTR provoca un defecto en el transporte de Cl– y un aumento de la reabsorción de sal y agua, en particular en el epitelio bronquial, lo que conlleva una reducción del líquido de la superficie bronquial. Esta exocrinopatía generalizada conduce a la producción de «moco viscoso» (de ahí el nombre de mucoviscidosis), que obstruye varios sitios en el cuerpo, en particular el sistema respiratorio, el tracto digestivo y sus anexos (páncreas, vías biliares e hígado). La detección neonatal se ha generalizado desde 2002. La prueba del sudor es la prueba complementaria de referencia, validada por la identificación de dos mutaciones patógenas, para la confirmación del diagnóstico. El tratamiento es multidisciplinario. Se basa ante todo en la kinesiterapia respiratoria diaria y el tratamiento de las sobreinfecciones broncopulmonares, así como en las recomendaciones nutricionales con el uso de extractos pancreáticos. Es probable que el pronóstico, todavía muy desfavorable, se modifique con la llegada de terapias proteínicas o de edición de ácido ribonucleico o de gen.

Derivation of induced pluripotent stem cells from ferret somatic cells

Ferrets are an attractive mammalian model for several diseases, especially those affecting the lungs, liver, brain, and kidneys. Many chronic human diseases have been difficult to model in rodents due to differences in size and cellular anatomy. This is particularly the case for the lung, where ferrets provide an attractive mammalian model of both acute and chronic lung diseases, such as influenza, cystic fibrosis, A1A emphysema, and obliterative bronchiolitis, closely recapitulating disease pathogenesis, as it occurs in humans. As such, ferrets have the potential to be a valuable preclinical model for the evaluation of cell-based therapies for lung regeneration and, likely, for other tissues. Induced pluripotent stem cells (iPSCs) provide a great option for provision of enough autologous cells to make patient-specific cell therapies a reality. Unfortunately, they have not been successfully created from ferrets. In this study, we demonstrate the generation of ferret iPSCs that reflect the primed pluripotent state of human iPSCs. Ferret fetal fibroblasts were reprogrammed and acquired core features of pluripotency, having the capacity for self-renewal, multilineage differentiation, and a high-level expression of the core pluripotency genes and pathways at both the transcriptional and protein level. In conclusion, we have generated ferret pluripotent stem cells that provide an opportunity for advancing our capacity to evaluate autologous cell engraftment in ferrets.

Phenotypic Characterization and Comparison of Cystic Fibrosis Rat Models Generated Using CRISPR/Cas9 Gene Editing

Animal models of cystic fibrosis (CF) are essential for investigating disease mechanisms and trialing potential therapeutics. This study generated two CF rat models using clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated protein 9 gene editing. One rat model carries the common human Phe508del (ΔF508) CF transmembrane conductance regulator (CFTR) mutation, whereas the second is a CFTR knockout model. Phenotype was characterized using a range of functional and histologic assessments, including nasal potential difference to measure electrophysiological function in the upper airways, RNAscope in situ hybridization and quantitative PCR to assess CFTR mRNA expression in the lungs, immunohistochemistry to localize CFTR protein in the airways, and histopathologic assessments in a range of tissues. Both rat models revealed a range of CF manifestations, including reduced survival, intestinal obstruction, bioelectric defects in the nasal epithelium, histopathologic changes in the trachea, large intestine, and pancreas, and abnormalities in the development of the male reproductive tract. The CF rat models presented herein will prove useful for longitudinal assessments of pathophysiology and therapeutics.

Current strategies and opportunities to manufacture cells for modeling human lungs

Chronic lung diseases remain major healthcare burdens, for which the only curative treatment is lung transplantation. In vitro human models are promising platforms for identifying and testing novel compounds to potentially decrease this burden. Directed differentiation of pluripotent stem cells is an important strategy to generate lung cells to create such models. Current lung directed differentiation protocols are limited as they do not 1) recapitulate the diversity of respiratory epithelium, 2) generate consistent or sufficient cell numbers for drug discovery platforms, and 3) establish the histologic tissue-level organization critical for modeling lung function. In this review, we describe how lung development has formed the basis for directed differentiation protocols, and discuss the utility of available protocols for lung epithelial cell generation and drug development. We further highlight tissue engineering strategies for manipulating biophysical signals during directed differentiation such that future protocols can recapitulate both chemical and physical cues present during lung development.

Deciphering the Ecology of Cystic Fibrosis Bacterial Communities: Towards Systems-Level Integration

Despite over a decade of cystic fibrosis (CF) microbiome research, much remains to be learned about the overall composition, metabolic activities, and pathogenicity of the microbes in CF airways, limiting our understanding of the respiratory microbiome's relation to disease. Systems-level integration and modeling of host-microbiome interactions may allow us to better define the relationships between microbiological characteristics, disease status, and treatment response. In this way, modeling could pave the way for microbiome-based development of predictive models, individualized treatment plans, and novel therapeutic approaches, potentially serving as a paradigm for approaching other chronic infections. In this review, we describe the challenges facing this effort and propose research priorities for a systems biology approach to CF lung disease.