Micro- and Nanoplastics as Emerging Cardiovascular Stressors: Mechanisms of Vascular Injury, Atherothrombosis, and Myocardial Dysfunction

Micro- and nanoplastics (MNPs) are gaining prominence as human-made pollutants that continuously enter the human body through ingestion, inhalation, and iatrogenic routes. Current analytical technologies utilizing vibrational chemical imaging and thermal degradation mass spectrometry have established that these materials enter blood circulation and accumulate in the human cardiovascular system (blood, arteries, plaques, thrombi, and myocardium). MNPs function as a unique combination of solid and chemical pollutants since the materials contain an insoluble polymer core, formulation-specific additives, such as phthalates and bisphenols that can leach into the surrounding milieu, and contaminants that adsorb to the surface. This phenomenon, called the “Trojan horse” effect, explains this property of MNPs. Experimental studies have demonstrated their ability to degrade the endothelial glycocalyx and uncouple endothelial nitric oxide synthase. MNPs also trigger mitochondrial stress, which activates the NLRP3 inflammasome pathway. These mechanisms can contribute to multiple cardiovascular diseases like atherosclerotic cardiovascular disease (ASCVD), acute coronary syndromes (ACS), heart failure, arrhythmia, and thromboembolism. The findings from human surgical cohorts show that there is a connection between polymer accumulation in plaques, the development of vascular inflammation, the structural vulnerability of plaques, and the incidence of major adverse cardiovascular events. However, it is important to understand that these results are not sufficient for establishing definitive clinical causality. Most human data come from cross-sectional studies that can suffer from reverse causation, such as when inflamed, hyperpermeable vascular walls allow the entrance of the pollutants without them being the direct cause of the disease. To reach a definite conclusion about the connection between MNPs and cardiovascular diseases, it is essential to conduct intervention studies and establish prospective longitudinal exposure cohorts.