Sargassum horneri containing polysaccharides and phenolic acids suppresses particulate matter-induced oxidative DNA damage in M1/M2-polarized alveolar macrophages (AM) of allergic asthma

Particulate matter (PM) can cause cellular oxidative damage and promote respiratory diseases. We have recently shown that Sargassum horneri ethanol extract (SHE) was composed of seven monosaccharides and three uronic acids including Fuc, Rha, Ara, Gal, Glc, Xyl, Man, GulA, GlcA and ManA. Molecular weight of SHE polysaccharides was 5.61±0.024 ×10⁴g/mol and the main phenolic acid of SHE was identified as gallic acid complex. SHE containing polysaccharides and phenolic acids reduces PM-induced oxidative stress in mice lung cells through ROS scavenging and metal chelating. In this study, we identify the role of alveolar macrophages (AMs) that are particularly subject to DNA damage induced by PM-triggered oxidative stress in lungs of allergic asthma mice. We scrutinize if PM exposure causes oxidative DNA damage in a specific type of polarized AMs preferentially. Further, we investigate whether SHE can reduce oxidative DNA damage in polarized AMs and, more importantly, ameliorate AMs polarization in PM-induced allergic asthma. We discover PM triggers prolonged oxidative stress to AMs, leading to lipid peroxidation in them and alveolar epithelial cells (AECs) in allergic asthma. Particularly, we uncover AMs are polarized to M2 phenotype (F4/80+CD206+) with enhanced oxidative DNA damage when subject to PM-induced oxidative stress. However, we find that SHE repairs oxidative DNA damage in M1- and M2-polarized AMs and reduces AMs polarization due to PM exposure.