The Evolution of a Pediatric Public Health Crisis: E-cigarette or Vaping-Associated Lung Injury.

E-cigarettes and vaping products were first introduced in the United States around 2007, and quickly grew in popularity. By 2014, e-cigarettes had become the most commonly used tobacco product among youth in the United States. An e-cigarette, or vaping, product use-associated lung injury (EVALI) outbreak was identified by the Centers for Disease Control and Prevention (CDC) in 2019, with many cases in the adolescent population. The CDC opened a national database of cases and launched a multistate investigation; reported cases reached a peak in September 2019. The CDC investigation found that a vaping liquid additive, vitamin E acetate, was strongly linked to the EVALI outbreak but determined that the decline in cases was likely multifactorial. Due to decreased cases and the identification of a potential cause of the outbreak, the CDC stopped collecting data on EVALI cases as of February 2020. However, e-cigarettes and vaping products have continued to be the most popular tobacco product among youth, though state and national regulations on these products have increased since 2016. While pediatric case series and studies have shown differences in clinical presentation and medical histories between pediatric and adult EVALI cases, the fact that cases are no longer tracked at a national level limits necessary information for pediatric clinicians and researchers. We describe the available literature on the diagnosis, pathophysiology, treatment, and outcomes of EVALI in the pediatric population, and provide clinical and public health recommendations to facilitate prevention and management of EVALI specific to pediatrics.

Lack of cystic fibrosis transmembrane conductance regulator disrupts fetal airway development in pigs.

Loss of cystic fibrosis transmembrane conductance regulator (CFTR) function causes cystic fibrosis (CF), predisposing the lungs to chronic infection and inflammation. In young infants with CF, structural airway defects are increasingly recognized before the onset of significant lung disease, which suggests a developmental origin and a possible role in lung disease pathogenesis. The role(s) of CFTR in lung development is unclear and developmental studies in humans with CF are not feasible. Young CF pigs have structural airway changes and develop spontaneous postnatal lung disease similar to humans; therefore, we studied lung development in the pig model (non-CF and CF). CF trachea and proximal airways had structural lesions detectable as early as pseudoglandular development. At this early developmental stage, budding CF airways had smaller, hypo-distended lumens compared to non-CF airways. Non-CF lung explants exhibited airway lumen distension in response to forskolin/IBMX as well as to fibroblast growth factor (FGF)-10, consistent with CFTR-dependent anion transport/secretion, but this was lacking in CF airways. We studied primary pig airway epithelial cell cultures and found that FGF10 increased cellular proliferation (non-CF and CF) and CFTR expression/function (in non-CF only). In pseudoglandular stage lung tissue, CFTR protein was exclusively localized to the leading edges of budding airways in non-CF (but not CF) lungs. This discreet microanatomic localization of CFTR is consistent with the site, during branching morphogenesis, where airway epithelia are responsive to FGF10 regulation. In summary, our results suggest that the CF proximal airway defects originate during branching morphogenesis and that the lack of CFTR-dependent anion transport/liquid secretion likely contributes to these hypo-distended airways.

Newborn Cystic Fibrosis Pigs Have a Blunted Early Response to an Inflammatory Stimulus.

RATIONALE: Studies suggest that inappropriate responses to proinflammatory stimuli might contribute to inflammation in cystic fibrosis (CF) lungs. However, technical challenges have made it difficult to distinguish whether altered responses in CF airways are an intrinsic defect or a secondary effect of chronic disease in their tissue of origin. The CF pig model provides an opportunity to study the inflammatory responses of CF airways at birth, before the onset of infection and inflammation. OBJECTIVES: To test the hypothesis that acute inflammatory responses are perturbed in porcine CF airways. METHODS: We investigated the inflammatory responses of newborn CF and non-CF pig airways following a 4-hour exposure to heat-killed Staphylococcus aureus, in vivo and in vitro. MEASUREMENTS AND MAIN RESULTS: Following an in vivo S. aureus challenge, markers of inflammation were similar between CF and littermate control animals through evaluation of bronchoalveolar lavage and tissues. However, transcriptome analysis revealed genotype-dependent differences as CF pigs showed a diminished host defense response compared with their non-CF counterparts. Furthermore, CF pig airways exhibited an increase in apoptotic pathways and a suppression of ciliary and flagellar biosynthetic pathways. Similar differences were observed in cultured airway epithelia from CF and non-CF pigs exposed to the stimulus. CONCLUSIONS: Transcriptome profiling suggests that acute inflammatory responses are dysregulated in the airways of newborn CF pigs.

CCL20 is an inducible product of human airway epithelia with innate immune properties.

Chemokine ligand 20 (CCL20) and human beta-defensins (HBDs) share structural and functional properties, including antiparallel beta-pleated sheet core structures, charge distribution, and signaling to adaptive immune cells via the highly selective CCR6 receptor. Because of their similarities, we hypothesized that in addition to its known adaptive immune signaling functions, CCL20 has antimicrobial properties and participates in pulmonary innate immunity. We found that primary cultures of human airway epithelial and cultured fetal lung explants expressed CCL20 mRNA. Expression of CCL20 transcripts were significantly induced by interleukin (IL)-1beta and tumor necrosis factor-alpha, and inhibited by dexamethasone. Primary cultures of airway epithelia secreted CCL20 both apically and basolaterally, and CCL20 abundance was increased over 30-fold with IL-1beta stimulation, achieving an estimated concentration of 167 ng/ml in airway surface liquid. CCL20 abundance in bronchoalveolar lavage fluid from patients with cystic fibrosis was nearly 90-fold higher compared with bronchoalveolar lavage fluid from healthy volunteers. Interestingly, CCL20 exhibited salt-sensitive antimicrobial activity, mainly against Gram-negative bacteria in low mug/ml concentrations. Additionally, apical washings from IL-1beta-stimulated primary cultures of human airway epithelia had significantly more antimicrobial activity than unstimulated controls. CCL20 rapidly permeabilized bacterial membranes with a time course intermediate to HBD-2 and HBD-3. Thus, CCL20 is a bi-functional peptide with both innate and adaptive immune properties that is regulated by inflammatory mediators, expressed by airway epithelia, and increased in cystic fibrosis airway secretions.

In vivo gene transfer using a nonprimate lentiviral vector pseudotyped with Ross River Virus glycoproteins.

Vectors derived from lentiviruses provide a promising gene delivery system. We examined the in vivo gene transfer efficiency and tissue or cell tropism of a feline immunodeficiency virus (FIV)-based lentiviral vector pseudotyped with the glycoproteins from Ross River Virus (RRV). RRV glycoproteins were efficiently incorporated into FIV virions, generating preparations of FIV vector, which after concentration attain titers up to 1.5 x 10(8) TU/ml. After systemic administration, RRV-pseudotyped FIV vectors (RRV/FIV) predominantly transduced the liver of recipient mice. Transduction efficiency in the liver with the RRV/FIV was ca. 20-fold higher than that achieved with the vesicular stomatitis virus G protein (VSV-G) pseudotype. Moreover, in comparison to VSV-G, the RRV glycoproteins caused less cytotoxicity, as determined from the levels of glutamic pyruvic transaminase and glutamic oxalacetic transaminase in serum. Although hepatocytes were the main liver cell type transduced, nonhepatocytes (mainly Kupffer cells) were also transduced. The percentages of the transduced nonhepatocytes were comparable between RRV and VSV-G pseudotypes and did not correlate with the production of antibody against the transgene product. After injection into brain, RRV/FIV preferentially transduced neuroglial cells (astrocytes and oligodendrocytes). In contrast to the VSV-G protein that targets predominantly neurons, <10% of the brain cells transduced with the RRV pseudotyped vector were neurons. Finally, the gene transfer efficiencies of RRV/FIV after direct application to skeletal muscle or airway were also examined and, although transgene-expressing cells were detected, their proportions were low. Our data support the utility of RRV glycoprotein-pseudotyped FIV lentiviral vectors for hepatocyte- and neuroglia-related disease applications.