Conditional reprogramming of pediatric airway epithelial cells: A new human model to investigate early-life respiratory disorders.

BACKGROUND: Airway epithelial cells (AEC) are quite difficult to access in newborns and infants. It is critically important to develop robust life-extended models to conduct translational studies in this age group. We propose the use of a recently described cell culture technology (conditionally reprogrammed cells-CRC) to generate continuous primary cell cultures from nasal and bronchial AEC of young children. METHODS: We collected nasal and/or bronchial AEC from a total of 23 subjects of different ages including newborns/infants/toddlers (0-2 years; N = 9), school-age children (4-11 years; N = 6), and a group of adolescent/adult donors (N = 8). For CRC generation, we used conditioned medium from mitotically inactivated 3T3 fibroblasts and Rho-associated kinase (ROCK) inhibitor (Y-27632). Antiviral immune responses were studied using 25 key antiviral genes and protein production of type III epithelial interferon (IFN λ1) after double-stranded (ds) RNA exposure. RESULTS: CRC derived from primary AEC of neonates/infants and young children exhibited: (i) augmented proliferative capacity and life extension, (ii) preserved airway epithelial phenotype after multiple passages, (iii) robust immune responses characterized by the expression of innate antiviral genes and parallel nasal/bronchial production of IFN λ1 after exposure to dsRNA, and (iv) induction of airway epithelial inflammatory and remodeling responses to dsRNA (eg, CXCL8 and MMP9). CONCLUSION: Conditional reprogramming of AEC from young children is a feasible and powerful translational approach to investigate early-life airway epithelial immune responses in humans.

The relationship between nasopharyngeal CCL5 and microbiota on disease severity among infants with bronchiolitis.

Emerging evidence suggests that the airway microbiota plays an important role in viral bronchiolitis pathobiology. However, little is known about the combined role of airway microbiota and CCL5 in infants with bronchiolitis. In this multicenter prospective cohort study of 1005 infants (age <1 year) hospitalized for bronchiolitis during 2011-2014, we observed statistically significant interactions between nasopharyngeal airway CCL5 levels and microbiota profiles with regard to the risk of both intensive care use (Pinteraction =.02) and hospital length-of-stay ≥3 days (Pinteraction =.03). Among infants with lower CCL5 levels, the Haemophilus-dominant microbiota profile was associated with a higher risk of intensive care use (OR, 3.20; 95%CI, 1.18-8.68; P=.02) and hospital length-of-stay ≥3 days (OR, 4.14; 95%CI, 2.08-8.24; P<.001) compared to the Moraxella-dominant profile. Conversely, among those with higher CCL5 levels, there were no significant associations between the microbiota profiles and these severity outcomes (all P≥.10).

Dysregulation of PLDN (pallidin) is a mechanism for platelet dense granule deficiency in RUNX1 haplodeficiency.

Essentials Platelet dense granule (DG) deficiency is a major abnormality in RUNX1 haplodeficiency patients. The molecular mechanisms leading to the platelet DG deficiency are unknown. Platelet expression of PLDN (BLOC1S6, pallidin), involved in DG biogenesis, is regulated by RUNX1. Downregulation of PLDN is a mechanism for DG deficiency in RUNX1 haplodeficiency. SUMMARY: Background Inherited RUNX1 haplodeficiency is associated with thrombocytopenia and platelet dysfunction. Dense granule (DG) deficiency has been reported in patients with RUNX1 haplodeficiency, but the molecular mechanisms are unknown. Platelet mRNA expression profiling in a patient previously reported by us with a RUNX1 mutation and platelet dysfunction showed decreased expression of PLDN (BLOC1S6), which encodes pallidin, a subunit of biogenesis of lysosome-related organelles complex-1 (BLOC-1) involved in DG biogenesis. PLDN mutations in the pallid mouse and Hermansky-Pudlak syndrome-9 are associated with platelet DG deficiency. Objectives We postulated that PLDN is a RUNX1 target, and that its decreased expression leads to platelet DG deficiency in RUNX1 haplodeficiency. Results Platelet pallidin and DG levels were decreased in our patient. This was also observed in two siblings from a different family with a RUNX1 mutation. Chromatin immunoprecipitation and electrophoretic mobility shift assays with phorbol ester-treated human erythroleukemia (HEL) cells showed RUNX1 binding to RUNX1 consensus sites in the PLDN1 5' upstream region. In luciferase reporter studies, mutation of RUNX1 sites in the PLDN promoter reduced activity. RUNX1 overexpression enhanced and RUNX1 downregulation decreased PLDN1 promoter activity and protein expression. RUNX1 downregulation resulted in impaired handling of mepacrine and mislocalization of the DG marker CD63 in HEL cells, indicating impaired DG formation, recapitulating findings on PLDN downregulation. Conclusions These studies provide the first evidence that PLDN is a direct target of RUNX1 and that its dysregulation is a mechanism for platelet DG deficiency associated with RUNX1 haplodeficiency.

Pharmacologically-induced mitotic synchrony in airway epithelial cells as a mechanism of action of anti-inflammatory drugs.

BACKGROUND: Mitotic synchrony is the synchronous progression of a population of cells through the cell cycle and is characteristic of non-diseased airway epithelial cells. However, we previously showed that asthmatic airway epithelial cells are characterized by mitotic asynchrony and are pro-inflammatory as a result. Glucocorticoids can induce mitotic synchrony that in turn suppresses the pro-inflammatory state of diseased cells, suggesting a novel anti-inflammatory mechanism of action. Herein, we benchmarked traditional glucocorticoids against the ability of a new clinical-stage dissociative steroidal drug, VBP15, for mitotic resynchronization and associated anti-inflammatory activity in asthmatic airway epithelial cells. METHODS: Primary airway epithelial cells differentiated at air-liquid interface were exposed to VBP15, dexamethasone or vehicle following in vitro mechanical injury. Basolateral cytokine secretions (TGF-ß1, IL-6, IL-10, IL-13, and IL-1ß) were analyzed at different time points using cytometric bead assays and mitosis was examined by flow cytometry. RESULTS: VBP15 improved mitotic synchrony of proliferating asthmatic cells in air-liquid interface cultures compared to vehicle-exposed cultures. VBP15 also significantly reduced the basolateral secretion of pro-inflammatory (i.e. IL-1ß) and pro-fibrogenic cytokines (i.e. TGF-ß1) in air-liquid interface-differentiated asthmatic epithelial cultures following mechanical injury. CONCLUSION: VBP15 improves mitotic asynchrony and injury-induced pro-inflammatory and fibrogenic responses in asthmatic airway epithelial cultures with efficacy comparable to traditional glucocorticoids. As it is predicted to show superior side effect profiles compared to traditional glucocorticoids, VBP15 holds potential for treatment of asthma and other respiratory conditions.