Litchi thaumatin-like protein induced the liver inflammation and altered the gut microbiota community structure in mice

The pro-inflammation activity of litchi thaumatin-like protein (LcTLP) was speculated to be the cause of the adverse reaction after excessive consumption of litchi. This study evaluated the pro-inflammation activity of LcTLP in vitro and in vivo. Results showed that LcTLP digested in vitro exhibited the pro-inflammation activity in RAW264.7 cells, as evidenced by an increase in pro-inflammation cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). After LcTLP supplementation in mice, pathological examination revealed the edematous cytoplasm and inflammatory cell accumulation in liver tissue. The levels of TNF-α, IL-1β, IL-6 and interleukin-10 in liver also increased by 60.43%, 74.86%, 120.18% and 129.91% in high-dose group, respectively, due to the upregulation of p-p65 and p-p38 levels and further activation of NF-κB and MAPK signaling pathways. Additionally, LcTLP altered the composition of gut microbiota, such as the reduction of Bacteroidota, norank_f__Muribaculaceae and norank_f__Lachnospiraceae abundances which were negatively correlated with inflammation cytokines levels.