The Role of Aging in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) has been gathering interest in recent years and as such this review will focus on the potential contributions that age plays on its onset and prevalence. Environmental stress over time caused by the inhalation of foreign substances results in subsequent damage and repair of lung tissue. This damage prematurely causes a decrease in stem cell differentiation potential. In conjunction with declining proliferation, the correlation between age and general attenuation of the immune system allows for the introduction of viral components such as the Epstein-Barr virus which has been associated with lung injury, a causation which has not yet been investigated. But, regardless of environmental factors, cellular alterations due to, or in correlation with, age could result in the onset or prolonging of IPF. General genetic mutation and epigenetic methylations accumulate over a person's lifespan while miRNA expression changes from birth to adulthood. This collection of alterations over time may cause dysregulation of expressed genetic material which can result in many age-related diseases including pulmonary fibrosis. Such alterations would be prevented by autophagy or cell-mediated apoptosis, but due to age-related dysregulations, these systems function at a diminished capacity. On the cellular level, the end result is an accumulation of dysfunctional organelles with damaged molecules, such as reactive oxygen species, and general genetic and epigenetic alterations resulting in excess generation of fibrous tissue and overall damage to the pulmonary system.