Particulate Matter (PM) as a Major Threat to Autophagy-Induced Homeostasis Regulation, a Systematic Review of the Literature

Background: Exposure to pollutants such as particulate matter (PM) disrupts homeostasis. The effect of PM on autophagy, as an essential factor of homeostasis, has been confirmed in several studies, but there is no comprehensive and detailed review of the mechanism involved. In this systematic review, we aim to investigate the mechanism involved in PM-induced autophagy of humans, animals, and cell lines.

Method: PubMed, Google Scholar, and Web of Science were searched using MESH terms related to PM and autophagy. Eligibility criteria were experimental studies in which PM was exposed and autophagy markers were assessed. Microtubule-associated protein 1A/1B-light chain 3-II (LC3-II), Beclin 1, and Sequestosome 1 (p62) are three important markers in the autophagy assay.

Result: Initially, 5842 articles were identified, of which 94 studies focused on the role of PMs in autophagy. Given the differences in exposure, we classified studies according to their type, “in vivo” or “in vitro.” A review of various studies has shown that, regardless of the exposure method, short-term exposure to PMs induced autophagy in almost all studies. In contrast, long-term exposure and pathological conditions can inhibit autophagy or block the flow of autophagy.

Conclusion: In living organisms, from unicellular organisms to large animals, autophagy supports cellular homeostasis under various conditions, such as exposure to pollutants. Chronic exposure to components such as PM or diseases can affect homeostasis by inducing nonphysiological conditions such as inflammation, excessive ROS production, and ultimately inhibition of autophagy.