Schizophyllan

Schizophyllan is an extracellular β-glucan synthesized by Schizophyllum commune. It improves mitochondrial function by activating the SIRT3 signaling pathway, thereby alleviating metabolic liver injury. Meanwhile, it inhibits JNK/p38 phosphorylation and downregulates the expression of PGC1β/PPARγ, c-Fos and NFATc1, thus suppressing osteoclast formation and promoting osteoblast differentiation. In addition, Schizophyllan enables targeted delivery of oligonucleotide drugs and antigens to antigen-presenting cells via Dectin-1-mediated recognition, showing broad application prospects in the treatment of inflammatory diseases and vaccine development.

Methods: Mouse bone marrow-derived macrophages, monocyte-osteoblast co-culture system, osteoblasts, RAW264 macrophages and primary hepatocytes were used as models to detect the effects of Schizophyllan on osteoclastogenesis, bone resorption, osteogenic mineralization, signaling pathways, molecular binding, antigen presentation and mitochondrial oxidative stress.
Results: :
1.Schizophyllan (5–200 μg/mL, 4–7 h) dose-dependently inhibited RANKL-induced osteoclast differentiation, TRAP activity, F-actin ring formation and bone resorption in mouse bone marrow macrophages. At 200 μg/mL, it reduced the number of mature osteoclasts by approximately 95% and almost completely blocked bone resorption.
2.Schizophyllan (200 μg/mL, 0–4 d) downregulated the expression of osteoclast differentiation marker genes induced by RANKL, and inhibited the JNK/p38 MAPK, PGC1β/PPARγ signaling pathways as well as the transcription factors c-Fos and NFATc1.
3.Schizophyllan (50–200 μg/mL, 1–6 d) dose-dependently inhibited osteoclast formation in the mouse bone marrow monocyte-osteoblast co-culture system; 200 μg/mL downregulated the expression of osteoclast-related factors Csf1 and Tnfsf11 in osteoblasts.
4.Schizophyllan (200 μg/mL, 7–24 d) slightly promoted the formation of mineralized nodules in mouse calvarial osteoblasts and upregulated the expression of osteogenic differentiation marker genes and transcription factors [1].
5.Schizophyllan (30 μg/mL) could specifically bind to soluble mouse Dectin-1 protein, among which dA60 (S)/SPG showed the strongest binding ability.
6.Schizophyllan could specifically hybridize with TNF-α sense RNA in vitro without dissociation from SPG.
7.Schizophyllan could deliver OVA257-264 peptide to mouse peritoneal macrophages, and the antigen presentation efficiency was equivalent to that of free conjugates.
8.Schizophyllan (0–24 h) was preferentially taken up by mouse RAW264 macrophages, and the uptake level continued to increase within 24 h [2].
9.Schizophyllan (100 μg/mL, 1–2 d) regulated the acetylation level and protein expression of SOD2 in primary hepatocytes of SOD2⁻/⁻ mice, and reduced mitochondrial ROS production in hepatocytes of wild-type mice in a SIRT3-dependent manner [3].

Methods: Schizophyllan was administered to ICR mice and wild‑type mice via subcutaneous injection and oral administration. Its ameliorative effects on LPS‑induced bone erosion and osteoclastogenesis, as well as the activation of SIRT3‑related pathways, liver injury and metabolic disorders were evaluated respectively.
Results: :
1.Schizophyllan (25 mg per mouse, subcutaneous injection, once daily for 9 consecutive days) could significantly inhibit LPS‑induced osteoclast formation and bone erosion in male ICR mice; the area of TRAP‑positive osteoclasts was reduced by approximately 40%, and the number was decreased by about 36% [1].
2.Schizophyllan (100 mg/kg, oral administration, once daily for 4–8 weeks) could upregulate SIRT3 expression in mouse liver and adipose tissue, activate SOD2 through deacetylation, and improve hepatic mitochondrial function in a SIRT3‑dependent manner.
3.Schizophyllan (100 mg/kg, oral administration, once daily for 4–8 weeks) could induce SIRT3‑mediated deacetylation and activation of SDHA in mouse brown adipose tissue.
4.Schizophyllan (100 mg/kg, oral administration, once daily for 6 weeks) could alleviate chronic ethanol‑induced liver injury in mice by activating the SIRT3‑SOD2 pathway, and restore hepatic structure and function.
5.Schizophyllan (100 mg/kg, oral administration, once daily for 20 weeks) could improve CLA‑induced metabolic abnormalities in mice by activating the SIRT3‑SDHA pathway, and recover tissue weight and serum biochemical indexes [3].

H2O: 1.46 mg/mL, when pH is adjusted to 12 with NaOH. Sonication and heating are recommended.