The Inhibitory Effect of Curosurf® and Alveofact® on the Formation of Neutrophil Extracellular Traps

Abstract

BackgroundNeutrophil extracellular traps (NETs) are a defense mechanism in which neutrophils cast a net-like structure in response to microbial infection. NETs consist of decondensed chromatin and about 30 enzymes and peptides. Some components, such as neutrophil elastase (NE) and myeloperoxidase (MPO), present antimicrobial but also cytotoxic properties, leading to tissue injury. Many inflammatory diseases are associated with NETs, and their final role has not been identified. Pulmonary surfactant is known to have immunoregulatory abilities that alter the function of adaptive and innate immune cells. The aim of this study was to investigate the hypothesis that natural surfactant preparations inhibit the formation of NETs.MethodsThe effect of two natural surfactants (Alveofact® and Curosurf®) on spontaneous and phorbol-12-myristate-13-acetate–induced NET formation by neutrophils isolated by magnetic cell sorting from healthy individuals was examined. NETs were quantitatively detected by absorption and fluorometric-based assays for the NET-specific proteins (NE, MPO) and cell-free DNA. Immunofluorescence microscopy images were used for visualization.ResultsBoth surfactant preparations exerted a dose-dependent inhibitory effect on NET formation. Samples treated with higher concentrations and with 30 min pre-incubation prior to stimulation with phorbol-12-myristate-13-acetate had significantly lower levels of NET-specific proteins and cell-free DNA compared to untreated samples. Immunofluorescence microscopy confirmed these findings.ConclusionsThe described dose-dependent modulation of NET formation ex vivo suggests an interaction between exogenous surfactant supplementation and neutrophil granulocytes. The immunoregulatory effects of surfactant preparations should be considered for further examination of inflammatory diseases.

Pulmonary surfactant as a versatile biomaterial to fight COVID-19

“…2 A) [ 65 ]. These interfacial films prevent alveolar collapse during expiration and thereby secures proper gas exchange [ 2 , [66] , [67] , [68] ]. The presence of PS is crucial for pulmonary homeostasis, as its absence, deficiency or inactivation is correlated with severe pulmonary diseases [ 67 , 69 ].…”

“…2 B, PS is mainly composed of lipids (~90 wt%) with dipalmitoylphosphatidylcholine (DPPC), a saturated phospholipid, being most abundant (~40 wt%). In addition, anionic lipids (~15 wt%) such as phosphatidylglycerol (PG), phosphatidylinositol (PI) and phosphatidylserine (PS) and neutral lipids such as cholesterol (~8 wt%) contribute to this lipid fraction [ 66 , 68 ]. The remaining 10 wt% consists of four highly specialized surfactant proteins (SPs), which can be divided in two groups based on their structural, physicochemical and functional properties, i.e.…”

“…Next to the well-known biophysical function essential for mammalian breathing, PS also contributes to the pulmonary innate immune system, protecting the alveoli from invading pathogens and other foreign particulate matter [ 29 , 66 ]. These properties are mainly assigned to SP-A and SP-D, two oligomeric proteins that belong to the family of collectins of which the role in the innate immune system can be explained by a dual mode-of-action [ 66 , 74 ]. First, it is reported that SP-A and SP-D have immunomodulatory properties.…”

“…In addition, SP-A and SP-D can directly bind to soluble pro-inflammatory mediators such as tumor necrosis factor (TNF)α and lipopolysaccharide (LPS), which results in the inhibition of their downstream inflammatory actions ( Fig. 3 ) [ 66 , 78 , 79 ]. Secondly, SP-A and SP-D bind to carbohydrates, phospholipids and glycolipids present on bacteria, viruses, yeasts and fungi, as well as to neutrophils and DNA via their CRD.…”

Neutrophil Extracellular Trap-Driven Occlusive Diseases

“…In this context, PF-1355 prevented excessive NETs formation and reduced leukocyte infiltration [ 121 ], making it a good candidate for further studies trying to interfere with NETs formation in occlusions. Furthermore, natural surfactants also have the ability to inhibit NETs formation in vitro [ 122 ]. Therefore, natural surfactants bear the potential to be used as therapeutical agents in occlusive conditions.…”