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Background In cystic fibrosis, the respiratory epithelium is the target tissue of both the genetic abnormality of the disease and of external aggressions, notably by pathogens (Pseudomonas aeruginosa). A detailed characterisation of the cystic fibrosis bronchial epithelium is however lacking, as most previous studies focused on the nasal epithelium or on cell lines. This study aimed to characterise the abnormal phenotype and epithelial-to-mesenchymal transition in cystic fibrosis bronchial epithelium and to evaluate in cell cultures whether abnormalities persist ex vivo. Methods Explant lung tissues (n = 44) were assessed for bronchial epithelial cell phenotyping by immunostaining. Human bronchial epithelial cells were derived from basal cells isolated from cystic fibrosis patients or control donors and cultured in air-liquid interface for 2, 4 or 6 weeks. Results Enhanced mucin 5AC and decreased β-tubulin expression were observed in cystic fibrosis airways reflecting a decreased ciliated/goblet cell ratio, associated with increased number of vimentin-positive cells, indicating epithelial-to-mesenchymal transition process. These features were recapitulated in vitro, in cystic fibrosis-derived reconstituted epithelium. However, they were not induced by CFTR inhibition or Pseudomonas infection, and most abnormalities tended to disappear in long-term culture (6 weeks) except for increased fibronectin release, an epithelial-to-mesenchymal transition marker. Conclusions This study provides new insights into airway epithelial changes in cystic fibrosis, which are imprinted through an acquired mechanism that we could not relate to CFTR function.

Background: In cystic fibrosis (CF), recurrent infections suggest impaired mucosal immunity but whether production of secretory immunoglobulin A (S-IgA) is impaired remains elusive. S-IgA is generated following polymeric immunoglobulin receptor (pIgR)-mediated transepithelial transport of dimeric (d-)IgA and represents a major defence through neutralisation of inhaled pathogens like Pseudomonas aeruginosa (Pa). Methods: Human lung tissue (n = 74), human sputum (n = 118), primary human bronchial epithelial cells (HBEC) (cultured in air-liquid interface) (n = 19) and mouse lung tissue and bronchoalveolar lavage were studied for pIgR expression, IgA secretion and regulation. Findings: Increased epithelial pIgR immunostaining was observed in CF lung explants, associated with more IgA-producing plasma cells, sputum and serum IgA, especially Pa-specific IgA. In contrast, pIgR and IgA transport were downregulated in F508del mice, CFTR-inhibited HBEC, and CF HBEC. Moreover, the unfolded protein response (UPR) due to F508del mutation, inhibited IgA transport in Calu-3 cells. Conversely, pIgR expression and IgA secretion were strongly upregulated following Pa lung infection in control and F508del mice, through an inflammatory host response involving interleukin-17. Interpretation: A complex regulation of IgA secretion occurs in the CF lung, UPR induced by CFTR mutation/dysfunction inhibiting d-IgA transcytosis, and Pa infection unexpectedly unleashing this secretory defence mechanism. Funding: This work was supported by the Forton's grant of the King Baudouin's Foundation, Belgium, the Fondazione Ricerca Fibrosi Cistica, Italy, and the Fonds National de la Recherche Scientifique, Belgium., SCOPUS: ar.j, info:eu-repo/semantics/published

Acquisition of proper neuronal identity and position is critical for the formation of neural circuits. In the embryonic spinal cord, cardinal populations of interneurons diversify into specialized subsets and migrate to defined locations within the spinal parenchyma. However, the factors that control interneuron diversification and migration remain poorly characterized. Here, we show that the Onecut transcription factors are necessary for proper diversification and distribution of the V2 interneurons in the developing spinal cord. Furthermore, we uncover that these proteins restrict and moderate the expression of spinal isoforms ofPou2f2, a transcription factor known to regulate B-cell differentiation. By gain- or loss-of-function experiments, we show that Pou2f2 contribute to regulate the position of V2 populations in the developing spinal cord. Thus, we uncovered a genetic pathway that regulates the diversification and the distribution of V2 interneurons during embryonic development.Significance statementIn this study, we identify the Onecut and Pou2f2 transcription factors as regulators of spinal interneuron diversification and migration, two events that are critical for proper CNS development.

Introduction: Immunoglobulin (Ig) A protects mucosal surfaces from inhaled pathogens and antigens. While serum and sputum IgA are increased, it remains unknown whether polymeric immunoglobulin receptor (pIgR)-mediated transepithelial transport of IgA is affected in cystic fibrosis (CF). Aims: We wondered whether broncho-epithelial pIgR-mediated transport of IgA is altered and could contribute to lung infection by Pseudomonas aeruginosa (PA). Methods: Lung tissue from 19 CF patients, as compared to 17 controls, was assayed for pIgR immunostaining. Sputum samples from 49 CF patients and 46 controls were assessed for IgA, secretory (S)-IgA, IgM, S-IgM, secretory component (SC) and PA-specific IgA and IgM, as well as neutrophil elastase (NE) activity. IgA and IgM. Total and PA-specific IgA and IgM were also measured in serum. Results: Increased epithelial pIgR immunostaining was observed in CF compared to controls, in large (56% versus 8, mean, p Conclusion: We report that, in contrast with COPD, broncho-epithelial pIgR expression is enhanced in CF and associates with an increased production of sputum IgA and IgM, including PA-specific antibodies, indicating that humoral immunity is upregulated in the CF lung.

Severe non-AIDS bacterial infections (SBI) are the leading cause of hospital admissions among people living with HIV (PLHIV) in industrialized countries. We aimed to estimate the incidence of SBI and their risk factors in a large prospective cohort of PLHIV patients over a 13-year period in France. Patients followed up in the ANRS CO3 Aquitaine cohort between 2000 and 2012 were eligible; SBI was defined as a clinical diagnosis associated with hospitalization of ≥48 hours or death. Survival analysis was conducted to identify risk factors for SBI.Total follow-up duration was 39,256 person-years [PY] (31,370 PY on antiretroviral treatment [ART]). The incidence of SBI decreased from 26.7/1000 PY [95% CI: 22.9-30.5] over the period 2000-2002 to 11.9/1000 PY [10.1-13.8] in 2009-2012 (p 50 copies/mL (Hazard Ratio [HR] = 5.1, 95% Confidence Interval: 4.2-6.2), CD4 count