Early pulmonary disease manifestations in cystic fibrosis mice

Club cell CREB regulates the goblet cell transcriptional network and pro-mucin effects of IL-1B

Introduction: Club cells are precursors for mucus-producing goblet cells. Interleukin 1β (IL-1B) is an inflammatory mediator with pro-mucin activities that increases the number of mucus-producing goblet cells. IL-1B-mediated mucin production in alveolar adenocarcinoma cells requires activation of the cAMP response element-binding protein (CREB). Whether the pro-mucin activities of IL-1B require club cell CREB is unknown. Methods: We challenged male mice with conditional loss of club cell Creb1 and wild type littermates with intra-airway IL-1B or vehicle. Secondarily, we studied human "club cell-like" H322 cells. Results: IL-1B increased whole lung mRNA of secreted (Mucin 5ac, Mucin 5b) and tethered (Mucin 1, Mucin 4) mucins independent of genotype. However, loss of club cell Creb1 increased whole lung mRNA of member RAS oncogene family (Rab3D), decreased mRNA of the muscarinic receptor 3 (M3R) and prevented IL-1B mediated increases in purinergic receptor P2Y, (P2ry2) mRNA. IL-1B increased the density of goblet cells containing neutral mucins in wildtype mice but not in mice with loss of club cell Creb1. These findings suggested that club cell Creb1 regulated mucin secretion. Loss of club cell Creb1 also prevented IL-1B-mediated impairments in airway mechanics. Four days of pharmacologic CREB inhibition in H322 cells increased mRNA abundance of forkhead box A2 (FOXA2), a repressor of goblet cell expansion, and decreased mRNA expression of SAM pointed domain containing ETS transcription factor (SPDEF), a driver of goblet cell expansion. Chromatin immunoprecipitation demonstrated that CREB directly bound to the promoter region of FOXA2, but not to the promoter region of SPDEF. Treatment of H322 cells with IL-1B increased cAMP levels, providing a direct link between IL-1B and CREB signaling. Conclusion: Our findings suggest that club cell Creb1 regulates the pro-mucin properties of IL-1B through pathways likely involving FOXA2.

Adjuvant effect of inhaled particulate matter containing free radicals following house-dust mite induction of asthma in mice

INTRODUCTION

Exposures to particulate matter (PM) from combustion sources can exacerbate preexisting asthma. However, the cellular and molecular mechanisms by which PM promotes the exacerbation of asthma remain elusive. We used a house dust mite (HDM)-induced mouse model of asthma to test the hypothesis that inhaled DCB230, which are PM containing environmentally persistent free radicals (EPFRs), will aggravate asthmatic responses.

METHODS

Groups of 8-10-week-old C57BL/6 male mice were exposed to either air or DCB230 aerosols at a concentration of 1.5 mg/m3 4 h/day for 10 days with or without prior HDM-induction of asthma.

RESULTS

Aerosolized DCB230 particles formed small aggregates (30-150 nm). Mice exposed to DCB230 alone showed significantly reduced lung tidal volume, overexpression of the Muc5ac gene, and dysregulation of 4 inflammation related genes, Ccl11, Ccl24, Il-10, and Tpsb2. This suggests DCB230 particles interacted with the lung epithelium inducing mucous hypersecretion and restricting lung volume. In addition to reduced lung tidal volume, compared to respective controls, the HDM + DCB230-exposed group exhibited significantly increased lung tissue damping and up-regulated expression of Muc5ac, indicating that in this model, mucous hypersecretion may be central to pulmonary dysfunction. This group also showed augmented lung eosinophilic inflammation accompanied by an up-regulation of 36 asthma related genes. Twelve of these genes are part of IL-17 signaling, suggesting that this pathway is critical for DCB230 induced toxicity and adjuvant effects in lungs previously exposed to HDM.

CONCLUSION

Our data indicate that inhaled DCB230 can act as an adjuvant, exacerbating asthma through IL-17-mediated responses in a HDM mouse model.

GAA deficiency disrupts distal airway cells in Pompe disease

Pompe disease is an autosomal recessive glycogen storage disease caused by mutations in the gene that encodes acid alpha-glucosidase (GAA)-an enzyme responsible for hydrolyzing lysosomal glycogen. GAA deficiency results in systemic lysosomal glycogen accumulation and cellular disruption. Glycogen accumulation in skeletal muscles, motor neurons, and airway smooth muscle cells is known to contribute to respiratory insufficiency in Pompe disease. However, the impact of GAA deficiency on the distal alveolar type 1 and type 2 cells (AT1 and AT2) has not been evaluated. AT1 cells rely on lysosomes for cellular homeostasis so that they can maintain a thin barrier for gas exchange, whereas AT2 cells depend on lysosome-like structures (lamellar bodies) for surfactant production. Using a mouse model of Pompe disease, the Gaa-/- mouse, we investigated the consequences of GAA deficiency on AT1 and AT2 cells using histology, pulmonary function and mechanics, and transcriptional analysis. Histological analysis revealed increased accumulation of lysosomal-associated membrane protein 1 (LAMP1) in the Gaa-/- mice lungs. Furthermore, ultrastructural examination showed extensive intracytoplasmic vacuoles enlargement and lamellar body engorgement. Respiratory dysfunction was confirmed using whole body plethysmography and forced oscillometry. Finally, transcriptomic analysis demonstrated dysregulation of surfactant proteins in AT2 cells, specifically reduced levels of surfactant protein D in the Gaa-/- mice. We conclude that GAA enzyme deficiency leads to glycogen accumulation in the distal airway cells that disrupts surfactant homeostasis and contributes to respiratory impairments in Pompe disease.NEW & NOTEWORTHY This research highlights the impact of Pompe disease on distal airway cells. Prior to this work, respiratory insufficiency in Pompe disease was classically attributed to pathology in respiratory muscles and motor neurons. Using the Pompe mouse model, we note significant pathology in alveolar type 1 and 2 cells with reductions in surfactant protein D and disrupted surfactant homeostasis. These novel findings highlight the potential contributions of alveolar pathology to respiratory insufficiency in Pompe disease.

Recruited monocytes/macrophages drive pulmonary neutrophilic inflammation and irreversible lung tissue remodeling in cystic fibrosis

Persistent neutrophil-dominated lung inflammation contributes to lung damage in cystic fibrosis (CF). However, the mechanisms that drive persistent lung neutrophilia and tissue deterioration in CF are not well characterized. Starting from the observation that, in patients with CF, c-c motif chemokine receptor 2 (CCR2)⁺ monocytes/macrophages are abundant in the lungs, we investigate the interplay between monocytes/macrophages and neutrophils in perpetuating lung tissue damage in CF. Here we show that CCR2⁺ monocytes in murine CF lungs drive pathogenic transforming growth factor β (TGF-β) signaling and sustain a pro-inflammatory environment by facilitating neutrophil recruitment. Targeting CCR2 to lower the numbers of monocytes in CF lungs ameliorates neutrophil inflammation and pathogenic TGF-β signaling and prevents lung tissue damage. This study identifies CCR2⁺ monocytes as a neglected contributor to the pathogenesis of CF lung disease and as a therapeutic target for patients with CF, for whom lung hyperinflammation and tissue damage remain an issue despite recent advances in CF transmembrane conductance regulator (CFTR)-specific therapeutic agents.

The circadian system in cystic fibrosis mice is regulated by histone deacetylase 6

Disordered sleep experienced by people with cystic fibrosis (CF) suggest a possible disruption in circadian regulation being associated with the loss of cystic fibrosis transmembrane conductance regulator (Cftr) function. To test this hypothesis, circadian regulation was assessed in an F508del/F508del CF mouse model. CF mice exhibited significant alterations in both timing of locomotor activity and in mean activity per hour in both light-dark (LD) and dark-dark (DD) photoperiods compared with wild-type (WT) controls. It was also noted that in DD periodicity increased in CF mice, whereas shortening in WT mice as is expected. CF mice also exhibited altered timing of circadian gene expression and a reduction of melatonin production at all time points. Mechanistically, the role of microtubules in regulating these outcomes was explored. Mice lacking expression of tubulin polymerization promoting protein (Tppp) effectively mimicked CF mouse phenotypes with each measured outcome. Depleting expression of the microtubule regulatory protein histone deacetylase 6 (Hdac6) from CF mice (CF/Hdac6) resulted in the reversal of each phenotype to WT profiles. These data demonstrate an innate disruption of circadian regulation in CF mice and identify a novel microtubule-related mechanism leading to this disruption that can be targeted for therapeutic intervention.

Bicarbonate transport of airway surface epithelia in luminally perfused mice bronchioles

HCO3- secretion in distal airways is critical for airway mucosal defense. HCO3-/H+ transport across the apical membrane of airway surface epithelial cells was studied by measuring intracellular pH in luminally microperfused freshly dissected mice bronchioles. Functional studies demonstrated that CFTR, ENaC, Cl--HCO3- exchange, Na+-H+ exchange, and Na+-HCO3- cotransport are involved in apical HCO3-/H+ transport. RT-PCR of isolated bronchioles detected fragments from Cftr, α, β, γ subunits of ENaC, Ae2, Ae3, NBCe1, NBCe2, NBCn1, NDCBE, NBCn2, Nhe1, Nhe2, Nhe4, Nhe5, Slc26a4, Slc26a6, and Slc26a9. We assume that continuous decline of intracellular pH following alkaline load demonstrates time course of HCO3- secretion into the lumen which is perfused with a HCO3--free solution. Forskolin-stimulated HCO3- secretion was substantially inhibited by luminal application of CFTRinh-172 (5 μM), H2DIDS (200 μM), and amiloride (1 μM). In bronchioles from a cystic fibrosis mouse model, basal and acetylcholine-stimulated HCO3- secretion was substantially impaired, but forskolin transiently accelerated HCO3- secretion of which the magnitude was comparable to wild-type bronchioles. In conclusion, we have characterized apical HCO3-/H+ transport in native bronchioles. We have demonstrated that cAMP-mediated and Ca2+-mediated pathways are involved in HCO3- secretion and that apical HCO3- secretion is largely mediated by CFTR and H2DIDS-sensitive Cl--HCO3- exchanger, most likely Slc26a9. The impairment of HCO3- secretion in bronchioles from a cystic fibrosis mouse model may be related to the pathogenesis of early lung disease in cystic fibrosis.

Serum inflammatory profiles in cystic fibrosis mice with and without Bordetella pseudohinzii infection

Cystic fibrosis (CF) is an autosomal recessive disease caused by dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) protein, and is marked by an accumulation of mucus in affected airways resulting in persistent infection and chronic inflammation. Quantitative differences in inflammatory markers have been observed in CF patient serum, tracheal cells, and bronchoalveolar lavage fluid, in the absence of detectable infection, implying that absent CFTR function alone may result in dysregulated immune responses. To examine the relationship between absent CFTR and systemic inflammation, 22 analytes were measured in CF mice (F508del/F508del) sera using the MSD multiplex platform. Pro-inflammatory cytokines IL-2, TNF-α, IL-17α, IFN-γ, IL-1β, and MIP-3α are significantly elevated in infection-naïve CF mice (p < 0.050). Anti-inflammatory cytokines IL-10 and IL-4 are also significantly increased (p = 0.00003, p = 0.004). Additionally, six general markers of inflammation are significantly different from non-CF controls (p < 0.050). To elucidate the effects of chronic infection on the CF inflammatory profile, we examined CF mice exposed to spontaneous Bordetella pseudohinzii infections. There are no statistical differences in nearly all inflammatory markers when compared to their infection-naïve CF counterparts, except in the Th2-derived IL-4 and IL-5 which demonstrate significant decreases following exposure (p = 0.046, p = 0.045). Lastly, following acute infection, CF mice demonstrate elevations in nearly all inflammatory markers, but exhibit a shortened return to uninfected levels over time, and suppression of Th1-derived IL-2 and IL-5 (p = 0.043, p = 0.011). These results imply that CF mice have a persistent inflammatory profile often indistinguishable from chronic infection, and a dysregulated humoral response during and following active infection.

MCTR1 Intervention Reverses Experimental Lung Fibrosis in Mice

Purpose

Pulmonary fibrosis (PF) is a progressing lethal disease, effective curative therapies remain elusive and mortality remains high. Maresin conjugates in tissue regeneration 1 (MCTR1) is a DHA-derived lipid mediator promoting inflammation resolution produced in macrophage. However, the effect of MCTR1 on PF remains unknown.

Material and Methods

We established a lung fibrosis model in mice induced by intratracheal administration of bleomycin (BLM). On day 7 after lung fibrosis model establishment, treatment with MCTR1 up to day 21. The body weight of each mouse was recorded every day and survival curves were plotted. Histological staining was used to detect pulmonary inflammation and fibrosis. Lung sections were examined with transmission electron microscope to evaluate the ultrastructure of cells and deposit of collagen. Inflammatory cytokines in lung tissues were tested by ELISA. q-PCR and Western blot were used to evaluate the mRNA and the protein levels of EMT-related markers.

Results

We found that MCTR1 intervention attenuated BLM-induced lung inflammatory and fibrotic response. Furthermore, MCTR1 protected BLM-induced epithelial cell destroy and reversed epithelial-to-mesenchymal transition phenotype into an epithelial one in lung fibrosis mice. Most importantly, post-treatment with MCTR1 restored BLM-induced lung dysfunction and enhanced survival rate significantly.

Conclusion

Posttreatment with MCTR1 attenuated BLM-induced inflammation and fibrosis changes in mice, suggested MCTR1 may serve as a novel therapeutic strategy for fibrosis-related diseases.

Oscillometry of the respiratory system: a translational opportunity not to be missed

Airway oscillometry has become the de facto standard for quality assessment of lung physiology in laboratory animals and has demonstrated its usefulness in understanding diseases of small airways. Nowadays, it is seeing extensive use in daily clinical practice and research; however, a question that remains unanswered is how well physiological findings in animals and humans correlate? Methodological and device differences are obvious between animal and human studies. However, all devices deliver an oscillated airflow test signal and output respiratory impedance. In addition, despite analysis differences, there are ways to interpret animal and human oscillometry data to allow suitable comparisons. The potential with oscillometry is its ability to reveal universal features of the respiratory system across species, making translational extrapolation likely to be predictive. This means that oscillometry can thus help determine if an animal model displays the same physiological characteristics as the human disease. Perhaps more importantly, it can also be useful to determine whether an intervention is effective as well as to understand if it affects the desired region of the respiratory system, e.g., the periphery of the lung. Finally, findings in humans can also inform preclinical scientists and give indications as to what type of physiological changes should be observed in animal models to make them relevant as models of human disease. The present article will attempt to demonstrate the potential of oscillometry in respiratory research, an area where the development of novel therapies is plagued with a failure rate higher than in other disease areas.

Animal models for cystic fibrosis: a systematic search and mapping review of the literature. Part 2: nongenetic models

Various animal models are available to study cystic fibrosis (CF). These models may help to enhance our understanding of the pathology and contribute to the development of new treatments. We systematically searched all publications on CF animal models. Because of the large number of models retrieved, we split this mapping review into two parts. Previously, we presented the genetic CF animal models. In this paper we present the nongenetic CF animal models. While genetic animal models may, in theory, be preferable for genetic diseases, the phenotype of a genetic model does not automatically resemble human disease. Depending on the research question, other animal models may thus be more informative.We searched Pubmed and Embase and identified 12,303 unique publications (after duplicate removal). All references were screened for inclusion by two independent reviewers. The genetic animal models for CF (from 636 publications) were previously described. The non-genetic CF models (from 189 publications) are described in this paper, grouped by model type: infection-based, pharmacological, administration of human materials, xenografts and other. As before for the genetic models, an overview of basic model characteristics and outcome measures is provided. This CF animal model overview can be the basis for an objective, evidence-based model choice for specific research questions. Besides, it can help to retrieve relevant background literature on outcome measures of interest.

Airway Epithelial Telomere Dysfunction Drives Remodeling Similar to Chronic Lung Allograft Dysfunction

Telomere dysfunction is associated with multiple fibrotic lung processes, including chronic lung allograft dysfunction (CLAD)-the major limitation to long-term survival following lung transplantation. Although shorter donor telomere lengths are associated with an increased risk of CLAD, it is unknown whether short telomeres are a cause or consequence of CLAD pathology. Our objective was to test whether telomere dysfunction contributes to the pathologic changes observed in CLAD. Histopathologic and molecular analysis of human CLAD lungs demonstrated shortened telomeres in lung epithelial cells quantified by teloFISH, increased numbers of surfactant protein C immunoreactive type II alveolar epithelial cells, and increased expression of senescence markers (β-galactosidase, p16, p53, and p21) in lung epithelial cells. TRF1^F/F (telomere repeat binding factor 1 flox/flox) mice were crossed with tamoxifen-inducible SCGB1a1-cre mice to generate SCGB1a1-creTRF1^F/F mice. Following 9 months of tamoxifen-induced deletion of TRF1 in club cells, mice developed mixed obstructive and restrictive lung physiology, small airway obliteration on microcomputed tomography, a fourfold decrease in telomere length in airway epithelial cells, collagen deposition around bronchioles and adjacent lung parenchyma, increased type II aveolar epithelial cell numbers, expression of senescence-associated β-galactosidase in epithelial cells, and decreased SCGB1a1 expression in airway epithelial cells. These findings demonstrate that telomere dysfunction isolated to airway epithelial cells leads to airway-centric lung remodeling and fibrosis similar to that observed in patients with CLAD and suggest that lung epithelial cell telomere dysfunction may be a molecular driver of CLAD.

Animal and Cell Culture Models for Cystic Fibrosis: Which Model Is Right for Your Application?

Over the past 30 years, a range of cystic fibrosis (CF) animal models have been generated for research purposes. Different species, including mice, rats, ferrets, rabbits, pigs, sheep, zebrafish, and fruit flies, have all been used to model CF disease. While access to such a variety of animal models is a luxury for any research field, it also complicates the decision-making process when it comes to selecting the right model for an investigation. The purpose of this review is to provide a guide for selecting the most appropriate CF animal model for any given application. In this review, the characteristics and phenotypes of each animal model are described, along with a discussion of the key considerations that must be taken into account when choosing a suitable animal model. Available in vitro systems of CF are also described and can offer a useful alternative to using animal models. Finally, the future of CF animal model generation and its use in research are speculated upon.

Electronic-Cigarette Vehicles and Flavoring Affect Lung Function and Immune Responses in a Murine Model

The use of electronic nicotine delivery systems (ENDS), also known as electronic-cigarettes (e-cigs), has raised serious public health concerns, especially in light of the 2019 outbreak of e-cig or vaping product use-associated acute lung injury (EVALI). While these cases have mostly been linked to ENDS that contain vitamin E acetate, there is limited research that has focused on the chronic pulmonary effects of the delivery vehicles (i.e., without nicotine and flavoring). Thus, we investigated lung function and immune responses in a mouse model following exposure to the nearly ubiquitous e-cig delivery vehicles, vegetable glycerin (VG) and propylene glycol (PG), used with a specific 70%/30% ratio, with or without vanilla flavoring. We hypothesized that mice exposed sub-acutely to these e-cig aerosols would exhibit lung inflammation and altered lung function. Adult female C57BL/6 mice (n = 11–12 per group) were exposed to filtered air, 70%/30% VG/PG, or 70%/30% VG/PG with a French vanilla flavoring for 2 h a day for 6 weeks. Prior to sacrifice, lung function was assessed. At sacrifice, broncho-alveolar lavage fluid and lung tissue were collected for lipid mediator analysis, flow cytometry, histopathology, and gene expression analyses. Exposures to VG/PG + vanilla e-cig aerosol increased lung tidal and minute volumes and tissue damping. Immunophenotyping of lung immune cells revealed an increased number of dendritic cells, CD4+ T cells, and CD19+ B cells in the VG/PG-exposed group compared to air, irrespective of the presence of vanilla flavoring. Quantification of bioactive lung lipids demonstrated a >3-fold increase of 2-arachidonoylglycerol (2-AG), an anti-inflammatory mediator, and a 2-fold increase of 12-hydroxyeicosatetraenoic acid (12-HETE), another inflammatory mediator, following VG/PG exposure, with or without vanilla flavoring. This suggests that e-cig aerosol vehicles may affect immunoregulatory molecules. We also found that the two e-cig aerosols dysregulated the expression of lung genes. Ingenuity Pathway Analysis revealed that the gene networks that are dysregulated by the VG/PG e-cig aerosol are associated with metabolism of cellular proteins and lipids. Overall, our findings demonstrate that VG and PG, the main constituents of e-liquid formulations, when aerosolized through an e-cig device, are not harmless to the lungs, since they disrupt immune homeostasis.

Dysregulation of Circadian Rhythm Gene Expression in Cystic Fibrosis Mice

Cystic fibrosis (CF) is autosomal recessive disease that affects multiple body systems. CF patients often experience sleep disturbances, altered sleep patterns, and sleep apnea. Sleep in mammals is controlled in part by circadian clock genes, including Clock, Bmal1, Period1, Period2, Cryptochrome1, and Cryptochrome2. The purpose of this study was to gain a better understanding of the biological underpinnings of disordered sleep experienced in CF. To accomplish this, we evaluated circadian clock gene expression profiles in CF and wildtype mice, divided into two subgroups each based on sleep condition. One subgroup of each genotype was permitted to maintain their sleep-wake cycle while the other was deprived of sleep for six hours prior to sacrifice. Brain, skeletal muscle, jejunum, colon, lung and adipose tissues were collected from each mouse. Quantitative polymerase chain reaction (PCR) was used to quantify expression of Clock, Bmal1, Period1, Period2, Cryptochrome1 and Cryptochrome2, and expression levels were compared between study groups. Our comparisons showed distinct differences between the CF groups and the wildtype groups under both sleep conditions. Additionally, we found the CF mice that had been sleep deprived had severely dysregulated expression of all measured genes in the lung apart from Cry1. Our findings suggest that (1) disordered sleep in CF may be caused by circadian system dysregulation and (2) the loss of the cystic fibrosis transmembrane conductance regulator (CFTR) is a causative factor in the dysregulated circadian clock gene expression profiles of CF mice.

Personalization of therapies in rare diseases: a translational approach for the treatment of cystic fibrosis

High variability in the response rates to treatments can make the interpretation of data from clinical trials very difficult, particularly in rare genetic diseases in which the enrolment of thousands of patients is problematic. Personalized medicine largely depends on the establishment of appropriate early detectors of drug efficacy that may guide the administration (or discontinuation) of specific treatments. Such biomarkers should be capable of predicting the therapeutic response of individual patients and of monitoring early benefits of candidate drugs before late clinical benefits become evident. The identification of these biomarkers implies a rigorous stepwise process of translation from preclinical evaluation in cultured cells, suitable animal models or patient-derived freshly isolated cells to clinical application. In this review, we will discuss how a process of research translation can lead to the implementation of functional and mechanistic disease-relevant biomarkers. Moreover, we will address how preclinical data can be translated into the clinic in a personalized medical approach that can provide the right drug to the right patient within the right timeframe.

Small adipose stores in cystic fibrosis mice are characterized by reduced cell volume, not cell number

Cystic fibrosis (CF) is a lethal genetic disorder that affects many organ systems of the body, including various endocrine and exocrine tissues. Health and survival positively associate with body mass, and as a consequence, CF clinical care includes high-fat, high-calorie diets to maintain and increase adipose tissue stores. Such strategies have been implemented without a clear understanding of the cause and effect relationship between body mass and patients' health. Here, we used CF mouse models, which display small adipose stores, to begin examining body fat as a prelude into mechanistic studies of low body growth in CF, so that optimal therapeutic strategies could be developed. We reasoned that low adiposity must result from reduced number and/or volume of adipocytes. To determine relative contribution of either mechanism, we quantified volume of intraperitoneal and subcutaneous adipocytes. We found smaller, but not fewer, adipocytes in CF compared with wild-type (WT) animals. Specifically, intraperitoneal CF adipocytes were one-half the volume of WT cells, whereas subcutaneous cells were less affected by the Cftr genotype. No differences were found in cell types between CF and WT adipose tissues. Adipose tissue CFTR mRNA was detected, and we found greater CFTR expression in intraperitoneal depots as compared with subcutaneous samples. RNA sequencing revealed that CF adipose tissue exhibited lower expression of several key genes of adipocyte function ( Lep, Pck1, Fas, Jun), consistent with low triglyceride storage. The data indicate that CF adipocytes contain fewer triglycerides than WT cells, and a role for CFTR in these cells is proposed. NEW & NOTEWORTHY Adipocytes in cystic fibrosis mice exhibit smaller size due to low triglyceride storage. Adipocyte cell number per fat pad is similar, implying triglyceride storage problem. The absence of CFTR function in adipose tissue has been proposed as a direct link to low triglyceride storage in cystic fibrosis.

Cystic Fibrosis Gene Therapy: Looking Back, Looking Forward

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes a cAMP-regulated anion channel. Although CF is a multi-organ system disease, most people with CF die of progressive lung disease that begins early in childhood and is characterized by chronic bacterial infection and inflammation. Nearly 90% of people with CF have at least one copy of the ΔF508 mutation, but there are hundreds of CFTR mutations that result in a range of disease severities. A CFTR gene replacement approach would be efficacious regardless of the disease-causing mutation. After the discovery of the CFTR gene in 1989, the in vitro proof-of-concept for gene therapy for CF was quickly established in 1990. In 1993, the first of many gene therapy clinical trials attempted to rescue the CF defect in airway epithelia. Despite the initial enthusiasm, there is still no FDA-approved gene therapy for CF. Here we discuss the history of CF gene therapy, from the discovery of the CFTR gene to current state-of-the-art gene delivery vector designs. While implementation of CF gene therapy has proven more challenging than initially envisioned; thanks to continued innovation, it may yet become a reality.

AGTR2 absence or antagonism prevents cystic fibrosis pulmonary manifestations

BACKGROUND

Pulmonary disease remains the primary cause of morbidity and mortality for individuals with cystic fibrosis (CF). Variants at a locus on the X-chromosome containing the type 2 angiotensin II receptor gene (AGTR2) were identified by a large GWAS as significantly associating with lung function in CF patients. We hypothesized that manipulating the angiotensin-signaling pathway may yield clinical benefit in CF.

METHODS

Genetic subset analysis was conducted on a local CF cohort to extend the GWAS findings. Next, we evaluated pulmonary function in CF mice with a deleted AGTR2 gene, and in those who were given subcutaneous injections of PD123,319, a selective AGTR2 antagonist for 12 weeks beginning at weaning.

RESULTS

The genetic subset analysis replicated the initial GWAS identified association, and confirmed the association of this locus with additional lung function parameters. Studies in genetically modified mice established that absence of the AGTR2 gene normalized pulmonary function indices in two independent CF mouse models. Further, we determined that pharmacologic antagonism of AGTR2 improved overall pulmonary function in CF mice to near wild-type levels.

CONCLUSIONS

These results identify that reduced AGTR2 signaling is beneficial to CF lung function, and suggest the potential of manipulating the angiotensin-signaling pathway for treatment and/or prevention of CF pulmonary disease. Importantly, the beneficial effects were not CF gene mutation dependent, and were able to be reproduced with pharmacologic antagonism. As there are clinically approved drugs available to target the renin-angiotensin signaling system, these findings may be quickly translated to human clinical trials.

Airway disease phenotypes in animal models of cystic fibrosis

In humans, cystic fibrosis (CF) lung disease is characterised by chronic infection, inflammation, airway remodelling, and mucus obstruction. A lack of pulmonary manifestations in CF mouse models has hindered investigations of airway disease pathogenesis, as well as the development and testing of potential therapeutics. However, recently generated CF animal models including rat, ferret and pig models demonstrate a range of well characterised lung disease phenotypes with varying degrees of severity. This review discusses the airway phenotypes of currently available CF animal models and presents potential applications of each model in airway-related CF research.

Cystic Fibrosis Mice Develop Spontaneous Chronic Bordetella Airway Infections

Chronic pulmonary disease and infection is the primary cause of morbidity and mortality in people with cystic fibrosis (CF). Though Pseudomonas aeruginosa, is most commonly found in the airways of individuals with CF, there is increasing appreciation for the diversity of the CF microbiome, including other taxa such as Bordetella. Here we describe the identification and impact of Bordetella pseudohinzii infection in CF mice, which previously have not been thought to develop spontaneous airway infections. We determined that CF mice are more susceptible to the B. pseudohinzii infections, and less able to resolve the infection than non-CF mice. Moreover, in both CF and non-CF mice, B. pseudohinzii infections lead to markedly reduced respiratory rates and a CF-specific immune response. These results establish the CF mouse model as an important tool for the study of CF-relevant infection and highlight the potential contribution of Bordetella to CF clinical pathology.

Strategies for the etiological therapy of cystic fibrosis

Etiological therapies aim at repairing the underlying cause of cystic fibrosis (CF), which is the functional defect of the cystic fibrosis transmembrane conductance regulator (CFTR) protein owing to mutations in the CFTR gene. Among these, the F508del CFTR mutation accounts for more than two thirds of CF cases worldwide. Two somehow antinomic schools of thought conceive CFTR repair in a different manner. According to one vision, drugs should directly target the mutated CFTR protein to increase its plasma membrane expression (correctors) or improve its ion transport function (potentiators). An alternative strategy consists in modulating the cellular environment and proteostasis networks in which the mutated CFTR protein is synthesized, traffics to its final destination, the plasma membrane, and is turned over. We will analyze distinctive advantages and drawbacks of these strategies in terms of their scientific and clinical dimensions, and we will propose a global strategy for CF research and development based on a reconciliatory approach. Moreover, we will discuss the utility of preclinical biomarkers that may guide the personalized, patient-specific implementation of CF therapies.

Posttreatment with Protectin DX ameliorates bleomycin-induced pulmonary fibrosis and lung dysfunction in mice

Protectin DX (10S,17S-dihydroxydocosa-4Z,7Z,11E,13Z,15E,19Z-hexaenoic acid) (PDX), generated from Ω-3 fatty docosahexaenoic acids, is believed to exert anti-inflammatory and proresolution bioactions. To date, few studies have been performed regarding its effect on pulmonary fibrosis. Herein we show that PDX exerts a potential therapeutic effect which is distinct from its anti-inflammation and pro-resolution activity on mice with pulmonary fibrosis. In the present study, we showed that bleomycin (BLM) increased inflammatory infiltration, collagen deposition, and lung dysfunction on day7 after challenged in mice. Posttreatment with PDX ameliorated BLM-induced inflammatory responses, extracellular matrix (ECM) deposition and the level of cytokines related to fibrosis as evaluated by histology analysis, transformation electron microscope (TEM), lung hydroxyproline content and cytokines test. Moreover, PDX improved lung respiratory function, remedied BLM-induced hypoxemia and prolonged life span. In addition, we found that PDX reversed epithelial–mesenchymal transition (EMT) phenotypic transformation in vivo and in vitro, reinforcing a potential mechanism of promoting fibrosis resolution. In summary, our findings showed that posttreatment with PDX could ameliorate BLM-induced pulmonary fibrosis and lung dysfunction in mice and PDX may be considered as a promising therapeutic approached to fibrotic lung diseases.

Cystic Fibrosis and the Nervous System

Cystic fibrosis (CF) is a life-shortening autosomal recessive disorder caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR is an anion channel that conducts bicarbonate and chloride across cell membranes. Although defective anion transport across epithelial cells is accepted as the basic defect in CF, many of the features observed in people with CF and organs affected by CF are modulated by the nervous system. This is of interest because CFTR expression has been reported in both the peripheral and central nervous systems, and it is well known that the transport of anions, such as chloride, greatly modulates neuronal excitability. Thus it is predicted that in CF, lack of CFTR in the nervous system affects neuronal function. Consistent with this prediction, several nervous system abnormalities and nervous system disorders have been described in people with CF and in animal models of CF. The goal of this special feature article is to highlight the expression and function of CFTR in the nervous system. Special emphasis is placed on nervous system abnormalities described in people with CF and in animal models of CF. Finally, features of CF that may be modulated by or attributed to faulty nervous system function are discussed.

Thymosin α1 represents a potential potent single-molecule-based therapy for cystic fibrosis

Cystic fibrosis (CF) is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) that compromise its chloride-channel activity. The most common mutation, p.Phe508del, results in the production of a misfolded CFTR protein, which has residual channel activity but is prematurely degraded. Because of the inherent complexity of the pathogenetic mechanisms involved in CF —which include impaired chloride permeability and persistent lung inflammation—a multidrug approach is required for efficacious CF therapy. To date, no individual, drug with pleiotropic beneficial effects for CF is available. Here we report on the ability of thymosin alpha 1 (Tα1)—a naturally occurring polypeptide with an excellent safety profile in the clinic when used as an adjuvant or an immunotherapeutic agent—to rectify the multiple tissue defects in CF mice as well as in cells from subjects with the p.Phe508del mutation. Tα1 displayed two combined properties that favorably opposed CF symptomatology; namely, it reduced inflammation and increased CFTR maturation, stability and activity. By virtue of this two-pronged action, Tα1 offers a strong potential to be an efficacious single molecule-based therapeutic agent in CF.

Growth deficits in cystic fibrosis mice begin in utero prior to IGF-1 reduction

Growth deficits are common in cystic fibrosis (CF), but their cause is complex, with contributions from exocrine pancreatic insufficiency, pulmonary complications, gastrointestinal obstructions, and endocrine abnormalities. The CF mouse model displays similar growth impairment despite exocrine pancreatic function and in the absence of chronic pulmonary infection. The high incidence of intestinal obstruction in the CF mouse has been suggested to significantly contribute to the observed growth deficits. Previous studies by our group have shown that restoration of the cystic fibrosis transmembrane conductance regulator (CFTR) in the intestinal epithelium prevents intestinal obstruction but does not improve growth. In this study, we further investigate growth deficits in CF and gut-corrected CF mice by assessing insulin-like growth factor 1 (IGF-1). IGF-1 levels were significantly decreased in CF and gut-corrected CF adult mice compared to wildtype littermates and were highly correlated with weight. Interestingly, perinatal IGF-1 levels were not significantly different between CF and wildtype littermates, even though growth deficits in CF mice could be detected late in gestation. Since CFTR has been suggested to play a role in water and nutrient exchange in the placenta through its interaction with aquaporins, we analyzed placental aquaporin expression in late-gestation CF and control littermates. While significant differences were observed in Aquaporin 9 expression in CF placentas in late gestation, there was no evidence of placental fluid exchange differences between CF and control littermates. The results from this study indicate that decreased IGF-1 levels are highly correlated with growth in CF mice, independent of CF intestinal obstruction. However, the perinatal growth deficits that are observed in CF mice are not due to decreased IGF-1 levels or differences in placenta-mediated fluid exchange. Further investigation is necessary to understand the etiology of early growth deficits in CF, as growth has been shown to be a significant factor in disease outcomes.

Weighted gene co-expression network analysis in identification of metastasis-related genes of lung squamous cell carcinoma based on the Cancer Genome Atlas database

BACKGROUND

Lung squamous cell carcinoma (lung SCC) is a common type of malignancy. Its pathogenesis mechanism of tumor development is unclear. The aim of this study was to identify key genes for diagnosis biomarkers in lung SCC metastasis.

METHODS

We searched and downloaded mRNA expression data and clinical data from The Cancer Genome Atlas (TCGA) database to identify differences in mRNA expression of primary tumor tissues from lung SCC with and without metastasis. Gene co-expression network analysis, protein-protein interaction (PPI) network, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and quantitative real-time polymerase chain reactions (qRT-PCR) were used to explore the biological functions of the identified dysregulated genes.

RESULTS

Four hundred and eighty-two differentially expressed genes (DEGs) were identified between lung SCC with and without metastasis. Nineteen modules were identified in lung SCC through weighted gene co-expression network analysis (WGCNA). Twenty-three DEGs and 26 DEGs were significantly enriched in the respective pink and black module. KEGG pathway analysis displayed that 26 DEGs in the black module were significantly enriched in bile secretion pathway. Forty-nine DEGs in the two gene co-expression module were used to construct PPI network. CFTR in the black module was the hub protein, had the connectivity with 182 genes. The results of qRT-PCR displayed that FIGF, SFTPD, DYNLRB2 were significantly down-regulated in the tumor samples of lung SCC with metastasis and CFTR, SCGB3A2, SSTR1, SCTR, ROPN1L had the down-regulation tendency in lung SCC with metastasis compared to lung SCC without metastasis.

CONCLUSIONS

The dysregulated genes including CFTR, SCTR and FIGF might be involved in the pathology of lung SCC metastasis and could be used as potential diagnosis biomarkers or therapeutic targets for lung SCC.

Molecular detection of virulence genes in Pseudomonas aeruginosa isolated from children with Cystic Fibrosis and burn wounds in Iran

Pseudomonas aeruginosa possesses various virulence factors which contribute to the bacterial invasion and toxicity. Moreover, children suffered from Cystic Fibrosis (CF) and burn wounds are at a high risk of various bacterial infections. The aim of this study was to determine the prevalence of virulent genes in P. aeruginosa isolated from children with CF and burn wounds and comparing their virulence genes to figure out the role of every virulent factor in the infections. P. aeruginosa were isolated from sputum, oropharyngeal swabs, and broncho-alveolar lavage (BAL) specimens from CF and burn wounds between June 2013 and June 2014 in Tehran's hospitals. Bacterial genomic DNAs were extracted and uniplex, duplex and multiplex PCR were performed for detection of toxA, algD and plcN, exoS, lasB, plcH genes, respectively. The prevalence rate of virulence genes in P. aeruginosa isolated from CF was; toxA (63.1%), algD (64.6%), plcH (87.7%), plcN (60%), lasB (95.4%) and exoS (70.8%) and virulence genes in P. aeruginosa from burn patients were: toxA (36.9%), algD (70.1%), plcH (79%), plcN (63.1%), lasB (82%) and exoS (21.1%). The prevalence of three virulent genes in P. aeruginosa was higher in CF comparing to burn wound infections. We found that the number of toxA, lasB and exoS were significantly higher in the bacteria which were isolated from children with CF. This finding shows that these virulence factors play an important role in CF infections by P. aeroginosa.