The bronchiolar epithelium as a prominent source of pro-inflammatory cytokines after lung irradiation

Conclusions: In the present study we have clearly demonstrated the immediate expression of the pro-inflammatory cytokines TNF-α, IL-1α, and IL-6 in the bronchiolar epithelium in the first hours after lung irradiation. A second, long-lasting release of these cytokines by the bronchiolar and alveolar epithelium, as well as by inflammatory cells, was observed at the onset of acute pneumonitis. Therefore, we postulate that lung irradiation causes immediate epithelial reaction, with the bronchiolar epithelium becoming a significant source of pro-inflammatory cytokines capable of promoting inflammation through recruitment and activation of inflammatory cells.