Isolation and characterization of an anti-tumor polysaccharide from Auricularia polytricha with dendritic cells maturation effect via TLR4/MyD88/NF-κB signaling pathway activation

Auricularia polytricha, a species of edible and medicinal fungus, has been utilized for thousands of years in both tonic and therapeutic applications. A polysaccharide, APP, has been isolated from Auricularia polytricha through hot-water extraction- ethanol precipitation, followed by DEAE-cellulose and Sephacryl S-400 HR chromatography purification. As characterized by size exclusion chromatography- multi-angle light scattering- differential refractive index, high-performance anion-exchange chromatography, UV–vis spectrum, Fourier Transform infrared spectra, scanning electronic microscope and X-ray diffraction, APP is a heteropolysaccharide composed of mannose, xylose, glucuronic acid, glucose, galactose and fucose, with a molecular weight of 221.694 kDa and contains α- and β-glycosidic bonds. APP could significantly suppress tumor growth and pulmonary metastasis in 4T1 tumor-bearing mice when combined with a single low dose of cyclophosphamide. Through ELISA, qRT-PCR, and Western blot analysis, APP was found to induce the maturation of bone marrow-derived dendritic cells by promoting the expression of costimulatory molecules, elevating secretion of Th1- and Th17-polarizing cytokines such as IL-6, IL-12p70, and IL-23 and enhancing mixed lymphocyte reaction. These activities are mediated via TLR4/MyD88/NF-κB signaling pathway activation. Collectively, these findings suggest new potential for the application of Aurciliaria polytricha in anti-tumor therapy, especially regarding the enhancement of immunogenic cell death and improvement of immunotherapeutic efficacy.