Pathogenesis and Risk Factors of Post-Infectious Bronchiolitis Obliterans in Children: A Focus on Adenovirus and Mycoplasma Infections

Post-infectious bronchiolitis obliterans (PIBO) is a severe chronic airway disease in children following lower respiratory tract infections. Human adenovirus (HAdV) and Mycoplasma pneumoniae (MP) are the major associated pathogens, with geographic variations in their relative importance. This review analytically compares the mechanistic divergence and convergence between HAdV and MP. Both pathogens converge on MyD88/NF-κB/MAPK signaling and neutrophil-driven inflammation, but diverge in initial host engagement (CAR/integrins vs. TLR2/6 and CARDS toxin) and inflammasome activation (TLR9-related vs. NLRP3-related). This review aims to propose an integrative model linking acute immune activation to fibrotic bronchiolar narrowing and to evaluate the risk factors for PIBO. Genetic susceptibility and epigenetic regulation help explain population differences in PIBO risk and geographic distribution. Despite progress, significant knowledge gaps remain, including the lack of single-cell resolution studies, the absence of co-infection animal models, and uncertainty regarding the long-term efficacy of targeted immunomodulatory therapies. Addressing these gaps is essential for improving early diagnosis and clinical outcomes.