Understanding Responses of Soil Microbiome to the Nitrogen and Phosphorus Addition in Metasequoia glyptostroboides Plantations of Different Ages.

Nitrogen (N) and phosphorus (P) have significant effects on soil microbial community diversity, composition, and function. Also, trees of different life stages have different fertilization requirements. In this study, we designed three N additions and three P levels (5 years of experimental treatment) at two Metasequoia glyptostroboides plantations of different ages (young, 6 years old; middle mature, 24 years old) to understand how different addition levels of N and P affect the soil microbiome. Here, the N fertilization of M. glyptostroboides plantation land (5 years of experimental treatment) significantly enriched microbes (e.g., Lysobacter, Luteimonas, and Rhodanobacter) involved in nitrification, denitrification, and P-starvation response regulation, which might further lead to the decreasing in alpha diversity (especially in 6YMP soil). The P addition could impact the genes involved in inorganic P-solubilization and organic P-mineralization by increasing soil AP and TP. Moreover, the functional differences in the soil microbiomes were identified between the 6YMP and 24YMP soil. This study provides valuable information that improves our understanding on the effects of N and P input on the belowground soil microbial community and functional characteristics in plantations of different stand ages.

Icaritin promotes tumor T-cell infiltration and induces antitumor immunity in mice.

Icaritin, a hydrolytic product of icariin isolated from traditional Chinese herbal medicine genus Epimedium, has many pharmacological and biological activities. Here, we show that icaritin can effectively decrease tumor burden of murine B16F10 melanoma and MC38 colorectal tumors in a T-cell dependent manner. The treatment effects are associated with increased CD8 T-cell infiltration and increased effector memory T-cell frequency. In vivo depletion of CD8 T cell using an anti-CD8 monoclonal antibody abolished the antitumor effect, which supports the critical role of CD8 T cells during icaritin treatment. By analyzing immune cells in the tumor tissue, we found reduced frequency of CD11b+ Gr1+ myeloid-derived suppression cells (MDSCs) infiltration and downregulation of PD-L1 expression on MDSCs after icaritin treatment. This was not limited to MDSCs, as icaritin also decreased the expression of PD-L1 on neutrophils. Importantly, the combination of anti-PD-1/CTLA-4 and icaritin significantly enhances antitumor ability and increases the efficacy of either treatment alone. Our findings reveal that icaritin induces antitumor immunity in a CD8 T-cell-dependent way and justify further investigation of combining immune checkpoint therapy to icaritin-based antitumor therapy.