Interactions of particulate matter and pulmonary surfactant: Implications for human health

Abstract

Particulate matter (PM), which is the primary contributor to air pollution, has become a pervasive global health threat. When PM enters into a respiratory tract, the first body tissues to be directly exposed are the cells of respiratory tissues and pulmonary surfactant. Pulmonary surfactant is a pivotal component to modulate surface tension of alveoli during respiration. Many studies have proved that PM would interact with pulmonary surfactant to affect the alveolar activity, and meanwhile, pulmonary surfactant would be adsorbed to the surface of PM to change the toxic effect of PM. This review focuses on recent studies of the interactions between micro/nanoparticles (synthesized and environmental particles) and pulmonary surfactant (natural surfactant and its models), as well as the health effects caused by PM through a few significant aspects, such as surface properties of PM, including size, surface charge, hydrophobicity, shape, chemical nature, etc. Moreover, in vitro and in vivo studies have shown that PM leads to oxidative stress, inflammatory response, fibrosis, and cancerization in living bodies. By providing a comprehensive picture of PM-surfactant interaction, this review will benefit both researchers for further studies and policy-makers for setting up more appropriate regulations to reduce the adverse effects of PM on public health.

An adverse outcome pathway for lung surfactant function inhibition leading to decreased lung function

“…The main advantages of this method include the accessibility of the air–liquid interface for exposure to airborne substances, flexibility in controlling cycling rates, and ease of determination of the surface tension in real-time while cycling the surfactant film. The constrained drop surfactometer has been applied to the exposure to a broad range of substances, including nanoparticles ( Larsen et al, 2020 , Valle et al, 2015 , Fan et al, 2011 , Yang et al, 2018 , Wang et al, 2020 ), individual chemicals ( Da Silva et al, 2021 ), mixtures of chemicals ( Da Silva, et al, 2021 , Sørli et al, 2018 , Sørli et al, 2016 ), excipients for drug formulation ( Sørli et al, 2018 ), per- and poly-fluoroalkyl substances ( Sørli et al, 2020 ), or plasma ( Autilio et al, 2021 ).…”

“…Structural changes can be identified during compression of the film when combined with epifluorescence or atomic force microscopy. These methods have been applied successfully to the study of changes induced by resin acids ( Jagalski et al, 2016 ), nanoparticles ( Wang et al, 2020 ), soot particles ( Fang et al, 2020 ), volatile organic substances ( Zhao et al, 2019 ), industrial chemicals ( Da Silva et al, 2021 ); tobacco smoke constituents ( Stenger et al, 2009 ), e-cigarette components ( Przybyla et al, 2017 ), spray products ( Larsen, et al, 2014 ), corticosteroids ( Wang et al, 2012 ), and biological components like cholesterol ( Zhang et al, 2012 , Taeusch et al, 2005 ), or meconium ( Lopez-Rodriguez et al, 2011 ).…”

Potential Therapeutic Applications of Pulmonary Surfactant Lipids in the Host Defence Against Respiratory Viral Infections

“…The remaining PC molecular species mainly include unsaturated lipids, such as 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) ( 2 , 3 ). The POPC in the surfactant film contributes to the membrane fluidity at physiological temperature, and unsaturated PC (PC16:0/16:1) is related to surface dynamics and respiratory rate ( 7 ). These unsaturated PCs improve the adsorption and spreading properties of surfactant at the air-liquid interface ( 8 ).…”

“…These unsaturated PCs improve the adsorption and spreading properties of surfactant at the air-liquid interface ( 8 ). Other pulmonary surfactant PLs such as PE, is important in facilitating/promoting curvature in some non-bilayer surfactant forms that are critical intermediates throughout the transitions from bilayers to interfacial films and their interconversions during surfactants metabolism ( 9 , 10 ); and PI can increase the rate of alveolar fluid clearance and stabilise the surfactant monolayer ( 7 ).…”

The Role of Pulmonary Surfactants in the Treatment of Acute Respiratory Distress Syndrome in COVID-19

“…The SPs are classified into hydrophilic SPs (SP-A and SP-D) and hydrophobic SPs (SP-B and SP-C; Figures 1C–F ). The details of SPs and PS lipids are provided in Table 1 ( Wang et al, 2020 ). SP-A and SP-D are highly ordered collagen-like oligomeric glycoprotein belonging to collectin family.…”