Comparative Analysis of Transcriptomes of Macrophage Revealing the Mechanism of the Immunoregulatory Activities of a Novel Polysaccharide Isolated from Boletus speciosus Frost

Background: The mechanism of the immunoregulatory activities of polysaccharide is still not clear. Materials and Methods: Here, we performed the B‑cell, T‑cell, and macrophage cell proliferation, the cell cycle analysis of macrophage cells, sequenced the transcriptomes of control group macrophages, and Boletus speciosus Frost polysaccharide (BSF‑1) group macrophages using Illumina sequencing technology to identify differentially expressed genes (DEGs) to determine the molecular mechanisms of immunomodulatory activity of BSF‑1 in macrophages. Results: These results suggested that BSF‑1 could promote the proliferation of B‑cell, T‑cell, and macrophages, promote the proliferation of macrophage cells by abolishing cell cycle arrests in the G0/G1 phases, and promote cell cycle progression in S‑phase and G2/M phase, which might induce cell division. A total of 12,498,414 and 11,840,624 bp paired‑end reads were obtained for the control group and BSF‑1 group, respectively, and they corresponded to a total size of 12.5 G bp and 11.8 G bp, respectively, after the low‑quality reads and adapter sequences were removed. Approximately 81.83% of the total number of genes (8,257) were expressed reads per kilobase per million mapped reads (RPKM ≥1) and more than 1366 genes were highly expressed (RPKM >60) in the BSF‑1 group. A gene ontology‑enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functions. A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the mitogen‑activated protein kinase (MAPK) signaling pathways are significantly enriched for DEGs between the two cell groups. Conclusion: An analysis of transcriptome resources enabled us to examine gene expression profiles, verify differential gene expression, and select candidate signaling pathways as the mechanisms of the immunomodulatory activity of BSF‑1. Based on the experimental data, we believe that the significant antitumor activities of BSF‑1 in vivo mainly involve the MAPK signaling pathways.