Properties of mixed monolayers of clinical lung surfactant, serum albumin and hydrophilic polymers

Potential health risks of the interaction of microplastics and lung surfactant

Microplastics (MPs), as pollutants of environmental concern, are correlated with increased risk of various respiratory diseases. Nevertheless, whether or not MPs have adverse influences on the interfacial properties of lung surfactant (LS), and its effect on the generation of reactive oxygen species are poorly understood. In the present study, natural LS extracted from porcine lungs was used to investigate the interaction with polystyrene as a representative MPs. The results showed that the phase behavior, surface tension, and membrane structure of the LS were altered in the presence of polystyrene. Adsorption experiments demonstrated that in the mixed system of polystyrene and LS (the main active ingredients are phospholipids and proteins), adsorption of phospholipid components by polystyrene was notably higher than that of proteins. Moreover, polystyrene can accelerate the conversion between ascorbic acid and deoxyascorbic acid, thereby producing hydrogen peroxide (HOOH) in simulated lung fluid (containing LS) and further giving rise to an increase in the content of hydroxyl radicals (•OH). This work provides new insight into the potential hazard of MPs in human respiratory system, which is helpful for deeply understanding the unfavorable physicochemical effects of MPs exposure and the role of inhaled MPs on lung health.

Interaction of inhalable volatile organic compounds and pulmonary surfactant: Potential hazards of VOCs exposure to lung

Exposure of volatile organic compounds (VOCs) towards lung leads to pulmonary dysfunctions and various lung diseases. However, the interaction of VOCs with pulmonary surfactant (PS) that directly comes into contact with inhaled VOCs is unknown. Here, simulated PS extracted from porcine lungs (EPS) was used to study the interaction with BTEX (i.e., benzene, toluene, ethylbenzene, and p-xylene) as representatives of VOCs. Surface pressure-area (π-A) isotherms showed that in the presence of individual BTEX, EPS monolayer's phase conversion from gas to liquid expanded phase was dramatically influenced and its collapse pressure decreased greatly compared to those of EPS alone, which was attributed to the alteration of EPS monolayer's microstructure characterized by atomic force microscopy and Brewster angle microscopy. Solubilization experiments manifested that EPS and its major components (dipalmitoyl phosphatidylcholine, DPPC; bovine serum albumin, BSA) exhibited obvious solubilization effects on individual BTEX. The solubilization capacity followed an order: EPS > DPPC > BSA, which was positively correlated with hydrophobicity of individual BTEX. Synergistic solubilization test unveiled that the mixed phospholipid components were largely responsible for the solubilization capacity of EPS. These findings indicate that VOCs exposure may induce potential pulmonary health risk due to the alteration of gas-liquid interfacial properties of PS.

Interaction of nano carbon particles and anthracene with pulmonary surfactant: The potential hazards of inhaled nanoparticles

Understanding the alteration of the air-liquid interfacial properties of pulmonary surfactant (PS) in the presence of nanoparticles (NPs) and polycyclic aromatic hydrocarbons (PAHs) is particularly important for pulmonary risk assessment. Here, we investigated the interaction of natural PS (extracted from pig's lungs) with nano carbon particles (NCPs) and anthracene as a representative PAH. Our results showed that PS exhibited a significant solubilization effect on anthracene. Solubilization experiment for the substructures of PS demonstrated that the mixed phospholipid components of PS played the primary role in the solubilization of PS for anthracene. Adsorption experiment indicated that in the mixed system of PS, NCPs, and anthracene, PS can inhibit the adsorption of anthracene on NCPs due to the solubilization, agglomeration, and competitive adsorption. In addition, the surface tension, phase behavior, and foaming ability of PS were obviously altered in the presence of NCPs. These findings indicate that the solubilization effect of PS on anthracene, the inhibitive effect of PS for the adsorption of anthracene on NCPs, and the alternation of air-liquid interfacial properties of PS containing NCPs may increase the pulmonary risk in the exposure of atmospheric environment containing both PAHs and NCPs.

Overcoming inactivation of the lung surfactant by serum proteins: a potential role for fluorocarbons?

In many pulmonary conditions serum proteins interfere with the normal adsorption of components of the lung surfactant to the surface of the alveoli, resulting in lung surfactant inactivation, with potentially serious untoward consequences. Here, we review the strategies that have recently been designed in order to counteract the biophysical mechanisms of inactivation of the surfactant. One approach includes protein analogues or peptides that mimic the native proteins responsible for innate resistance to inactivation. Another perspective uses water-soluble additives, such as electrolytes and hydrophilic polymers that are prone to enhance adsorption of phospholipids. An alternative, more recent approach consists of using fluorocarbons, that is, highly hydrophobic inert compounds that were investigated for partial liquid ventilation, that modify interfacial properties and can act as carriers of exogenous lung surfactant. The latter approach that allows fluidisation of phospholipid monolayers while maintaining capacity to reach near-zero surface tension definitely warrants further investigation.

Biophysicochemical Interaction of a Clinical Pulmonary Surfactant with Nanoalumina

We report on the interaction of pulmonary surfactant composed of phospholipids and proteins with nanometric alumina (Al2O3) in the context of lung exposure and nanotoxicity. We study the bulk properties of phospholipid/nanoparticle dispersions and determine the nature of their interactions. The clinical surfactant Curosurf, both native and extruded, and a protein-free surfactant are investigated. The phase behavior of mixed surfactant/particle dispersions was determined by optical and electron microscopy, light scattering, and zeta potential measurements. It exhibits broad similarities with that of strongly interacting nanosystems such as polymers, proteins or particles, and supports the hypothesis of electrostatic complexation. At a critical stoichiometry, micron-sized aggregates arising from the association between oppositely charged vesicles and nanoparticles are formed. Contrary to the models of lipoprotein corona or of particle wrapping, our work shows that vesicles maintain their structural integrity and trap the particles at their surfaces. The agglomeration of particles in surfactant phase is a phenomenon of importance that could change the interactions of the particles with lung cells.

Surface-active drug loaded lipopolymeric nanohybrid aerosol therapy: potential non-invasive way to mitigate lipopolysaccharide mediated inflammation in murine lungs

Non-invasive aerosol therapy of surface-active lipopolymeric nanohybrids co-delivers two drugs in inflamed lungs and also replenishes the depleted lung surfactant pool in inflamed alveoli following cellular uptake by the cells.