Immunity, Inflammation and Lung Fibrosis

The role of the immune system in idiopathic pulmonary fibrosis (IPF) pathogenesis has been debated, with seemingly contradictory results between promising experimental data and disappointing clinical trials. As the understanding of the paramount role of the epithelium in the disease arose, the concept that immunity and inflammation influence rather than drive fibrosis developed. Immune cells involved in both innate and adaptive immunity have been implicated in experimental fibrosis development and display alterations in idiopathic pulmonary fibrosis, shaping a pro-fibrotic environment. Accordingly, the levels of several cytokines with a pro-fibrotic potential, such as IL-4, IL-13, IL-1β, TNF-α and IL-17A are elevated in IPF patients. Additionally, the interplay with cellular stress components such as danger associated molecular patterns and infectious alarm signals under the form of pathogen associated molecular patterns is an area of ongoing investigation. Finally, recent advances in sequencing techniques have unraveled a potential role for viruses and bacteria.