Protective effects of strawberry and mulberry fruit polysaccharides on inflammation and apoptosis in murine primary splenocytes

This study isolated polysaccharides from strawberry (SP) and mulberry (MP) fruit juice to compare their cytokine secretion regulatory and antiapoptotic activities using murine primary splenocytes. SP and MP in the absence or presence of lipopolysaccharide (LPS) were administered to splenocytes for 48 hours. The culture supernatant was used for cytokine secretion assay using the enzyme-linked immunosorbent assay method. The cell pellet was used for the determination of anti-/proapoptotic protein (B cell lymphoma 2/Bak) levels in the cells using the Western blotting method. The results showed that SP and MP treatment at appropriate concentrations significantly increased the proliferation of splenocytes (p < 0.05). SP and MP treatments in the absence of LPS, and SP treatments in the presence of LPS significantly decreased T helper type 1/T helper type 2 (p < 0.05), and SP in the presence of LPS slightly decreased tumor necrosis factor-α/interleukin-10 (pro-/anti-inflammatory) cytokine secretion ratios by splenocytes, suggesting that SP has strong and MP has mild anti-inflammation potential via modulating cytokine secretion profiles. However, MP treatment at an appropriate concentration in the absence of LPS exhibited an antiapoptotic activity via modulating pro- (Bak) and antiapoptotic (B cell lymphoma 2) protein expression ratios, suggesting that MP may protect primary immune cells from apoptotic cell death. Overall, our findings suggest that SP has better anti-inflammation potential, whereas MP has better cell proliferation and antiapoptotic potential in vitro.