Polysaccharide from Abelmoschus esculentus L. flower ameliorates cyclophosphamide-induced immunosuppression via the TLR4/endocytosis and MAPK-NF-κB signaling pathways in mice

The present study was designed to investigate the immunomodulatory effects and mechanisms of a Abelmoschus esculentus L. flower polysaccharide (AEFP22) in the CTX-induced immunosuppressed mice. After intragastric gavage of AEFP22 for two weeks, nonspecific immunity, humoral immunity, cellular immunity and the status of immune organs were improved significantly in immunosuppressed mice. The immunoglobulins, cytokines and nitric oxide (NO) in serum also increased notably. Transcriptome analysis of the spleen showed that most immune-related differentially expressed genes (DEGs) were regulated inversely in the AEFP22-treated group and model group. Based on gene ontology (GO) analysis and Kyoto Encyclopedia of genes and genomes (KEGG) enrichment analysis of the transcriptome, the expression of key proteins in the toll-like receptor (TLR)4/endocytosis and mitogen-activated protein kinase (MAPK)-nuclear factor kappa B (NF-κB) signaling pathways were evaluated. The results showed that AEFP22 could ameliorate CTX-induced immunosuppression by increasing the expression of TLR4, myeloid differentiation primary response (MyD)88, TNF receptor associated factor (TRAF) 6 and major histocompatibility complex (MHC) class Ⅱ, enhance the phosphorylation of MAPKs and promote the nuclear translocation of NF-κB. This study indicated the immunoregulatory activity and potential mechanisms of AEFP22, which suggested the potential role of AEFP22 as an effective immunomodulator.