Biogenic Polyphosphate Nanoparticles from Synechococcus sp. PCC 7002 Exhibit Intestinal Protective Potential in Human Intestinal Epithelial Cells In Vitro and Murine Small Intestine Ex Vivo

Abstract

Polyphosphates are one of the active compounds from probiotics to maintain gut health. The current research extracted and purified intact biogenic polyphosphate nanoparticles (BPNPs) from Synechococcus sp. PCC 7002 cells. BPNPs were near-spherical anionic particles (56.9 ± 15.1 nm) mainly composed of calcium and magnesium salt of polyphosphate and were colloidally stable at near-neutral and alkaline pH. BPNPs survived gastrointestinal digestion in mice and could be absorbed and transported by polarized Caco-2 cell monolayers. They dose-dependently increased the tightness of intercellular tight junction and the expression of claudin-4, occludin, zonula occludens-1, and heat shock protein 27 in Caco-2 cell monolayers. BPNPs also effectively attenuated H₂O₂-induced cell death, plasma membrane impairment, and intracellular superoxide production in NCM460 cells. In addition, they conferred resistance to H₂O₂-induced barrier disruption in freshly excised mouse small intestine. Our results suggest that BPNPs are a promising postbiotic nanomaterial with potential applications in gut health maintenance.

Keywords: Caco-2 cell monolayer; Synechococcus sp. PCC 7002; biogenic polyphosphate nanoparticles; cytoprotective activities; intestinal permeability.