Impact of soyasaponin I on TLR2 and TLR4 induced inflammation in the MUTZ-3-cell model

Previous studies have demonstrated that soyasaponin (SoSa) possesses anti-inflammatory properties in lipopolysaccharide (LPS)-stimulated immune cells by influencing the immune sensing of toll-like receptor (TLR) 4. The aim of this study was to investigate the immune modulatory effect of SoSa I on TLR2- and TLR4-induced inflammation within the monocytic MUTZ-3-cell model. MUTZ-3 cells were stimulated with gram-negative (Escherichia coli) or gram-positive (Staphylococcus aureus) bacteria or bacterial pathogen-associated molecular patterns (PAMPs) such as LPS or peptidoglycans (PGN) alone or in combination with SoSa I. Cell morphology was characterized by raster scanning and light microscopy. Cytokine production (IL-1β, IL-6, TNF-α, IP-10, RANTES and IL-8) was measured by cytometric bead array and the expression of surface markers was assessed by flow cytometry. MUTZ-3 cells revealed a cell maturation-like alteration in morphology and increased expression of CD80, CD86, TLR2 and TLR4 after stimulation with either gram-negative and gram-positive bacteria or bacterial PAMPs. The addition of SoSa I suppressed pro-inflammatory cytokine and chemokine secretions in a dose-dependent manner regardless of TLR2 or TLR4 stimulation. Interestingly, E. coli- and S. aureus-induced inflammation was always inhibited better by SoSa I than that induced by LPS and PGN. Additionally, SoSa I reduced the expression of CD86 in PGN- or LPS-stimulated cells. This study demonstrated that the anti-inflammatory capacity of SoSa I is based on influencing both monocytic TLR2 and TLR4 and that SoSa I inhibits more effectively whole bacteria compared to solely LPS or PGN what points to a broader role of SoSa I in the down-regulation of inflammation.