Effect of gangliosides on LPS stimulation and nitric oxide release in porcine kidney cell line PK15

Abstract

Gangliosides, which are glycosphingolipids containing sialic acid, play important regulatory roles in cell proliferation and adhesion, survival and immunosuppressive activity. In this study, we investigated whether gangliosides can affect cell viability in the porcine kidney (PK) cell line, PK15, when stimulated with lipopolysaccharide (LPS). As the amount of LPS that PK15 cells were treated with was increased, the cell proliferation decreased, whereas nitric oxide (NO) production increased. High-performance thin-layer chromatography (HPTLC) and immunofluorescence analyses showed that GM3 and GM2 ganglioside expression significantly decreased in LPS-stimulated PK15 compared to unstimulated PK15. UDP-glucose ceramide glucosyltransferase (Ugcg), which catalyzes the initial step in the glycosphingolipid biosynthesis pathway, was knocked-down in PK15 by using short hairpin RNA (shRNA). Western blot and HPTLC analyses showed that the Ugcg protein expression decreased and the ganglioside expression decreased in the Ugcg-knockdown (UKD) PK15. There was a greater decrease in cell proliferation in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. However, the increase in NO release was greater in LPS-stimulated UKD PK15 cells than in LPS-stimulated PK15 cells without the UKD. These findings suggest that gangliosides may interact with components of the inflammatory response pathway and, thus, are relevant for the design of future therapeutic strategies intended to prolong xenotransplantation.