To alleviate the adverse effects of chemotherapy and bolster immune function, a novel polysaccharide derived from Sargassum fusiforme named as SFP-αII. The structural composition of SFP-αII predominantly consisted of guluronic and mannuronic acids in a molar ratio of 33.8:66.2, with an average molecular weight of 16.5 kDa. Its structure was primarily characterized by →4)-α-GulA-(1 → and →4)-β-ManA-(1 → linkages confirmed by FT-IR, methylation, and NMR analyses. The absence of a triple-helix structure was in SFP-αII was confirmed using circular dichroism and Congo red dye assays. The dimensions varied with lengths ranging from 20 nm up to 3 μm revealed by atomic force microscopy (AFM). SFP-αII has been found to enhance immunomodulatory activity in cyclophosphamide (CTX)-induced immunosuppressed mice. This was evidenced by improvements in immune organ indices, cytokine levels, and the release of nitric oxide (NO). Specifically, SFP-αII mitigated immunosuppression by upregulating the secretion of IL-1β (167.3 %) and TNF-α (227.1 %) at a dose of 400 mg/kg, compared with the CTX group in macrophages. Ultimately, SFP-αII may serve as a mechanism for immune enhancement through modulation of TLR4-mediated NF-κB and MAPK signaling pathways. This integration of traditional Chinese and Western medicine, leveraging SFP-αII as a potential functional food could be pivotal in alleviating immunosuppressive side effects in CTX treatment.

This study evaluates the immune-enhancing effects of Limosilactobacillus fermentum on cyclophosphamide (CP)-induced immunosuppression in BALB/c mice. In vitro, the expressions of pro-inflammatory cytokines and MAPK signaling molecules in Raw264.7 cells were analyzed by ELISA and Western blot analysis. Moreover, cell proliferation, surface receptor expression, and cytotoxicity of NK-92 cells were examined by Cell Counting Kit-8, CytoTox96 assay, and flow cytometry, respectively. To investigate the immune-enhancing effects of selected L. fermentum strains in vivo, these strains were orally administered to BALB/c mice for 2 weeks, and CP was intraperitoneally injected. Then, liver, spleen, and whole blood were isolated from each animal. Administration of single L. fermentum strains or their mixture sustained the spleen weight, the counts of white blood cells compared to non-fed group. Splenocyte proliferation and NK cytotoxicity were significantly increased in all L. fermentum-fed groups. The frequency of B220+ cells was also significantly enhanced in splenocytes isolated from L. fermentum groups. In addition, the production of cytokines (TNF-α, IFN-γ) and antibodies was recovered in splenocyte supernatants isolated from L. fermentum groups. In conclusion, L. fermentum could be a suitable functional food additive for immune-enhancing effect.

Immune-enhancing effects of three kinds of purple sweet potato polysaccharides (PSPPs) including water-soluble polysaccharide (WSP), dilute alkali-soluble polysaccharide (DASP) and concentrated alkali-soluble polysaccharide (CASP) were evaluated. Scanning electron microscope analysis showed that all PSPPs could stimulate the formation of microvilli-like structures in cellular surfaces, which was possibly related to activation of macrophages. Neutral red uptake assay showed that PSPPs could increase the phagocytic activity of cells. High dose (400 μg/mL) of PSPPs could notably augment the level of nitric oxide (NO). ELISA analysis revealed that 200 and 400 μg/mL of PSPPs distinctly elevated the production of IL-1β. Cells received 200 and 400 μg/mL of WSP as well as 400 μg/mL of DASP exhibited higher level of IL-6. Results of animal experiments showed that WSP treatment (400 mg/kg) could promote the secretions of IgA, IgG, IgM and sIgA in both normal and immunosuppressed mice. Moreover, CASP treatment (400 mg/kg) elevated the production of IgM in the serum of normal and immunosuppressive mice, while DASP (400 mg/kg) only improved the secretion of IgM in normal mice. In summary, all three polysaccharides can stimulate immune responses of macrophages and positively regulate adaptive immunity by enhancing the production of immunoglobulins in mice.