An Ex Vivo Model of Post Infectious Bronchiolitis Obliterans in Children Using Reconstituted Human Bronchial Epithelium

Introduction: Post-infectious bronchiolitis obliterans (PIBO) is a rare and severe chronic lung disease. Our goal was to characterize respiratory epithelium in children with PIBO, which remains unexplored, using an ex vivo model culture. Methods: Proximal bronchial biopsies from children with PIBO and reconstituted bronchial epithelium from PIBO patients (n = 3) and controls (n = 17) were analyzed using an air–liquid interface culture model. Epithelial cell composition, barrier integrity, and mediator production, including mucins, inflammatory and antiviral responses, were assessed in this pathological and functional approach. Results: Epithelial thickness was assessed in PIBO biopsies. Ex vivo reconstituted PIBO epithelia appeared to exhibit comparable cohesion and cell composition to controls. Mucin expression and secretion were likewise similar between groups. PIBO epithelial might have displayed reduced IL-33 transcript levels and decreased TSLP secretion, whereas IFN-λ1, IFN-λ2-3 and IFN-β secretion could have been elevated. No differences were detected in remodeling markers (MMP-9 and YKL-40). Conclusions: In summary, ex vivo model of PIBO epithelia suggested that the epithelium may preserve structural characteristics and mucin production, without evidence of remodeling. However, PIBO epithelial cells may have a distinct immune profile, with lower alarmin expression and higher interferon secretion. This could indicate a tendency toward enhanced antiviral response rather than structural changes. These preliminary results need to be confirmed in larger cohorts.