Computed Tomography (CT) Scanning Facilitates Early Identification of Neonatal Cystic Fibrosis Piglets

A Developmental Role of the Cystic Fibrosis Transmembrane Conductance Regulator in Cystic Fibrosis Lung Disease Pathogenesis

The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein is a cAMP-activated anion channel that is critical for regulating fluid and ion transport across the epithelium. This process is disrupted in CF epithelia, and patients harbouring CF-causing mutations experience reduced lung function as a result, associated with the increased rate of mortality. Much progress has been made in CF research leading to treatments that improve CFTR function, including small molecule modulators. However, clinical outcomes are not necessarily mutation-specific as individuals harboring the same genetic mutation may present with varying disease manifestations and responses to therapy. This suggests that the CFTR protein may have alternative functions that remain under-appreciated and yet can impact disease. In this mini review, we highlight some notable research implicating an important role of CFTR protein during early lung development and how mutant CFTR proteins may impact CF airway disease pathogenesis. We also discuss recent novel cell and animal models that can now be used to identify a developmental cause of CF lung disease.

TLR5 signalling is hyper-responsive in porcine cystic fibrosis airways epithelium

Excessive lung inflammation and airway epithelium damage are hallmarks of cystic fibrosis (CF) disease. It is unclear whether lung inflammation is related to an intrinsic defect in the immune response or to chronic infection. We aimed to determine whether TLR5-mediated response is defective in the CF airway epithelium. We used a newborn CF pig model to study intrinsic alterations in CF airway epithelium innate immune response. Airway epithelial cells (AECs) were stimulated with flagellin or lipopolysaccharide to determine responses specific for TLR5 and TLR4, respectively. We observed a significant increase in cytokine secretion when CF AECs were stimulated with flagellin compared to wild type (WT) AECs. These results were recapitulated when AECs were treated with an inhibitor of CFTR channel activity. We show that TLR5-signalling is altered in CF lung epithelium at birth. Modulation of TLR5 signalling could contribute to better control the excessive inflammatory response observed in CF lungs.

Airway Administration of Flagellin Regulates the Inflammatory Response to Pseudomonas aeruginosa

Excessive lung inflammation and airway epithelial damage are hallmarks of human inflammatory lung diseases, such as cystic fibrosis (CF). Enhancement of innate immunity provides protection against pathogens while reducing lung-damaging inflammation. However, the mechanisms underlying innate immunity–mediated protection in the lung remain mysterious, in part because of the lack of appropriate animal models for these human diseases. TLR5 (Toll-like receptor 5) stimulation by its specific ligand, the bacterial protein flagellin, has been proposed to enhance protection against several respiratory infectious diseases, although other cellular events, such as calcium signaling, may also control the intensity of the innate immune response. Here, we investigated the molecular events prompted by stimulation with flagellin and its role in regulating innate immunity in the lung of the pig, which is anatomically and genetically more similar to humans than rodent models. We found that flagellin treatment modulated NF-κB signaling and intracellular calcium homeostasis in airway epithelial cells. Flagellin pretreatment reduced the NF-κB nuclear translocation and the expression of proinflammatory cytokines to a second flagellin stimulus as well as to Pseudomonas aeruginosa infection. Moreover, in vivo administration of flagellin decreased the severity of P. aeruginosa–induced pneumonia. Then we confirmed these beneficial effects of flagellin in a pathological model of CF by using ex vivo precision-cut lung slices from a CF pigz model. These results provide evidence that flagellin treatment contributes to a better regulation of the inflammatory response in inflammatory lung diseases such as CF.

Intrinsic alterations in peripheral neutrophils from cystic fibrosis newborn piglets

BACKGROUND

The hallmark of the cystic fibrosis (CF) lung disease is a neutrophil dominated lung environment that is associated to chronic lung tissue destruction and ultimately the patient's death. It is unclear whether the exacerbated neutrophil response is primary related to a defective CFTR or rather secondary to chronic bacterial colonization and inflammation. Here, we hypothesized that CF peripheral blood neutrophils present intrinsic alteration at birth before the start of an inflammatory process.

METHODS

Peripheral blood neutrophils were isolated from newborn CFTR^+/+ and CFTR^-/- piglets. Neutrophils immunophenotype was evaluated by flow cytometry. Lipidomic and proteomic profile were characterized by liquid chromatography/tandem mass spectrometry (LC-MS/MS), intact cell matrix-assisted laser desorption/ionization mass spectrometry (ICM-MS) followed by top-down high-resolution mass spectrometry (HRMS), respectively. The ability of CF neutrophils to kill pseudomonas aeruginosa was also evaluated.

RESULTS

Polyunsaturated fatty acid metabolites analysis did not show any difference between CFTR^+/+ and CFTR^-/- neutrophils. On the other hand, a predictive mathematical model based on the ICM-MS proteomic profile was able to discriminate between both genotypes. Top-down proteomic analysis identified 19 m/z differentially abundant masses that corresponded mainly to proteins related to the antimicrobial response and the generation of reactive oxygen species (ROS). However, no alteration in the ability of CFTR^-/- neutrophils to kill pseudomonas aeruginosa in vitro was observed.

CONCLUSIONS

ICM-MS demonstrated that CFTR^-/- neutrophils present intrinsic alterations already at birth, before the presence of any infection or inflammation.

CFTR-deficient pigs display alterations of bone microarchitecture and composition at birth

BACKGROUND

The lack of cystic fibrosis transmembrane conductance regulator (CFTR) function causes cystic fibrosis (CF), predisposing to severe lung disease, reduced growth and osteopenia. Both reduced bone content and strength are increasingly recognized in infants with CF before the onset of significant lung disease, suggesting a developmental origin and a possible role in bone disease pathogenesis. The role of CFTR in bone metabolism is unclear and studies on humans are not feasible. Deletion of CFTR in pigs (CFTR ^-/- pigs) displays at birth severe malformations similar to humans in the intestine, respiratory tract, pancreas, liver, and male reproductive tract.

METHODS

We compared bone parameters of CFTR ^-/- male and female pigs with those of their wild-type (WT) littermates at birth. Morphological and microstructural properties of femoral cortical and trabecular bone were evaluated using micro-computed tomography (μCT), and their chemical compositions were examined using Raman microspectroscopy.

RESULTS

The integrity of the CFTR ^-/- bone was altered due to changes in its microstructure and chemical composition in both sexes. Low cortical thickness and high cortical porosity were found in CFTR ^-/- pigs compared to sex-matched WT littermates. Moreover, an increased chemical composition heterogeneity associated with higher carbonate/phosphate ratio and higher mineral crystallinity was found in CFTR ^-/- trabecular bone, but not in CFTR ^-/- cortical bone.

CONCLUSIONS

The loss of CFTR directly alters the bone composition and metabolism of newborn pigs. Based on these findings, we speculate that bone defects in patients with CF could be a primary, rather than a secondary consequence of inflammation and infection.

Preclinical septic shock research: why we need an animal ICU

Animal experiments are widely used in preclinical medical research with the goal of disease modeling and exploration of novel therapeutic approaches. In the context of sepsis and septic shock, the translation into clinical practice has been disappointing. Classical animal models of septic shock usually involve one-sex-one-age animal models, mostly in mice or rats, contrasting with the heterogeneous population of septic shock patients. Many other factors limit the reliability of preclinical models and may contribute to preclinical research failure in critical care, including the host specificity of several pathogens, the fact that laboratory animals are raised in pathogen-free facilities and that organ support techniques are either absent or minimal. Advanced animal models have been developed with the aim of improving the clinical translatability of experimental findings. So-called animal ICUs refer to the preclinical investigation of adult or even aged animals of either sex, using—in case of rats and mice—miniaturized equipment allowing for reproducing an ICU environment at a small animal scale and integrating chronic comorbidities to more closely reflect the clinical conditions studied. Strength and limitations of preclinical animal models designed to decipher the mechanisms involved in septic cardiomyopathy are discussed. This article reviews the current status and the challenges of setting up an animal ICU.

Insights on animal models to investigate inhalation therapy: Relevance for biotherapeutics

Acute and chronic respiratory diseases account for major causes of illness and deaths worldwide. Recent developments of biotherapeutics opened a new era in the treatment and management of patients with respiratory diseases. When considering the delivery of therapeutics, the inhaled route offers great promises with a direct, non-invasive access to the diseased organ and has already proven efficient for several molecules. To assist in the future development of inhaled biotherapeutics, experimental models are crucial to assess lung deposition, pharmacokinetics, pharmacodynamics and safety. This review describes the animal models used in pulmonary research for aerosol drug delivery, highlighting their advantages and limitations for inhaled biologics. Overall, non-clinical species must be selected with relevant scientific arguments while taking into account their complexities and interspecies differences, to help in the development of inhaled medicines and ensure their successful transposition in the clinics.