Comparative analysis of macrophage transcriptomes reveals a key mechanism of the immunomodulatory activity of Tricholoma matsutake polysaccharide.

In the present study, we performed a proliferation assay, phagocytosis assay and cell cycle analysis of macrophages and sequenced the transcriptomes of control group macrophages and TMP-A group macrophages using Illumina sequencing technology to identify differentially expressed genes (DEGs) and determine the molecular mechanisms associated with differences in the immunomodulatory activity of TMP-A in macrophages. The results showed that TMP-A exhibits strong proliferation activity and phagocytosis activity in RAW264.7 cells in vitro and could also promote the proliferation of macrophage cells by abolishing cell-cycle arrest in the G0/G1 phase and promoting the cell cycle in the G2/M phase, which may induce cell division. A total of 12,616,096 and 11,798,839 bp paired-end reads were obtained for the control group and TMP-A group, respectively, and they corresponded to a total size of 12.5 G bp and 11.7 G bp, respectively, after the low-quality reads and adapter sequences were removed. Approximately 79.8% of the total number of genes (10,191) were expressed (RPKM ≥1), and more than 1,372 genes were highly expressed (RPKM >60) in the TMP-A group. A total of 1,043 unigenes were identified as DEGs, and approximately 486 genes were upregulated, whereas 557 genes were down-regulated, which might have contributed to the proliferation activity and phagocytosis activity of TMP-A in the RAW264.7 cells in vitro. A Gene Ontology (GO) enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functions. A KEGG pathway enrichment analysis showed that the MAPK and NF-κB signaling pathways are significantly enriched for DEGs between the two cell groups. Based on the experimental data, we believe that the significant antitumor activities of TMP-A in vivo involve the MAPK and NF-κB signaling pathways because the two signaling pathways intersect.