What Do We Need to Know About Rising Rates of Idiopathic Pulmonary Fibrosis? A Narrative Review and Update

Abstract

The most common type of idiopathic interstitial pneumonia is idiopathic pulmonary fibrosis (IPF), an irreversible, progressive disorder that has lately come into question for possible associations with COVID-19. With few geographical exceptions, IPF is a rare disease but its prevalence has been increasing markedly since before the pandemic. Environmental exposures are frequently implicated in IPF although genetic factors play a role as well. In IPF, healthy lung tissue is progressively replaced with an abnormal extracellular matrix that impedes normal alveolar function while, at the same time, natural repair mechanisms become dysregulated. While chronic viral infections are known risk factors for IPF, acute infections are not and the link to COVID-19 has not been established. Macrophagy may be a frontline defense against any number of inflammatory pulmonary diseases, and the inflammatory cascade that may occur in patients with COVID-19 may disrupt the activity of monocytes and macrophages in clearing up fibrosis and remodeling lung tissue. It is unclear if COVID-19 infection is a risk factor for IPF, but the two can occur in the same patient with complicating effects. In light of its increasing prevalence, further study of IPF and its diagnosis and treatment is warranted.

Keywords: COVID-19; Idiopathic pulmonary fibrosis; Interstitial pneumonia; Macrophagy.

Fig. 1

Axial computed tomography (CT) image (a) shows diffuse irregular interstitial thickening with extensive honeycombing, more evident in the subpleural region of the right lower lobe; there is evidence of bronchiectasis,irregular pleural and fissural surfaces; and reduced volume of the right lung. Coronal CT reconstruction (b) shows that fibrotic changes are more widespread in the subpleural region of the lower lobes, especially in the right lung with reduced right-lung volume