Innate immune activation and antitumor effects of Lactobacillus-fermented Sparassis crispa extract in mice

Abstract

• Lacto -fermented Sparassis crispa (LFSC) extract has high β(1–3)-glucan content. • LFSC’s antitumor activity has a different mechanism from that of fluorouracil. • NK cells, neutrophils, and M1 macrophages increased after LFSC oral treatment. • LFSC promoted apoptosis and reactive oxygen species generation in tumors. Sparassis crispa (SC), a mushroom abundantly containing β(1–3)-glucan, is known to activate the innate immunity. Lactic acid bacteria are also known to activate the immunity. Here, we investigated the effects of SC and Lactobacillus -fermented SC (LFSC) on the innate immunity and tumor growth in mice. LFSC treatment promoted the higher accumulation of innate immune cells than the SC treatment. However, the antitumor activity of the LFSC was lower than that of the fluorouracil (5-FU). Furthermore, LFSC significantly reduced the serum levels of interleukin-6 in mice and enhanced the apoptosis rate and the production of reactive oxygen species in mouse tumor tissues. These effects were not observed in 5-FU-treated mice. LFSC also significantly enhanced the phagocytic activity of and the mRNA expression of thrombotic/inflammatory factors in human monocytes. These findings suggest that LFSC significantly enhances the innate immunity and exhibits antitumor effects by a mechanism different from that of 5-FU.