Abstract: BACKGROUND: For knee osteoarthritis, synovium inflammation and abnormal proliferation and activation of fibroblast-like synoviocytes caused by insufficient apoptosis are important driving factors for disease progression. Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway plays a key role in regulating inflammatory response and apoptosis of synovial cells. As a traditional Mongolian medicine component, Agiophyllum Oligo Saccharides has anti-inflammatory and immunomodulatory functions, but its specific molecular mechanism has not been fully revealed.
OBJECTIVE: To explore the effects and mechanism of Agiophyllum Oligo Saccharides on lipopolysaccharide-induced inflammation and apoptosis of mouse synovial cells.
METHODS: The mouse synovial cells were randomly divided into a control group, a model group, an Agiophyllum Oligo Saccharides group and a Bay 11-7082 group. Osteoarthritic synoviocyte model was prepared using 1.0 µg/mL lipopolysaccharide intervention for 36 hour. The Agiophyllum Oligo Saccharides group was treated with 1.0 µg/mL lipopolysaccharide and 32 µg/mL Agiophyllum Oligo Saccharides for 36 hours; and the Bay 11-7082 group was firstly incubated for 4 hours with 1 μmol/L NF-κB pathway inhibitor Bay 11-7082, and then 1.0 µg/mL lipopolysaccharide and 32 µg/mL Agiophyllum Oligo Saccharides for 36 hours. Western blot was used to detect TLR4, MyD88, NF-κBp65, p-NF-κBp65, and IκBα protein expression. The level of tumor necrosis factor-α and interleukin-1β in the supernatant were analyzed by ELISA. To detect the expressions of Bax and Bcl-2, western blot and immunofluorescence analysis were performed. The intracellular reactive oxygen species level was detected by DCFH-DA.
RESULTS AND CONCLUSION: (1) Compared with the control group, the levels of tumor necrosis factor-α, interleukin-1β and reactive oxygen species, the protein expressions of TLR4, MyD88, Bcl-2, and p-NF-κBp65/ NF-κBp65 increased (P < 0.05), whereas the protein expressions of IκBα and Bax decreased (P < 0.05) in the model group. (2) Compared with the model group, the levels of tumor necrosis factor-α, interleukin-1β and reactive oxygen species, the protein expressions of TLR4, MyD88, Bcl-2, and p-NF-κBp65/NF-κBp65 decreased (P < 0.05), while the expressions of IκBα and BAX increased (P < 0.05) in the Agiophyllum Oligo Saccharides group. (3) The levels of tumor necrosis factor-α, interleukin-1β and reactive oxygen species and the protein expression of Bcl-2 in the Bay 11-7082 group were higher than those in the Agiophyllum Oligo Saccharides group (P < 0.05), but still lower than those in the model group (P < 0.05), whereas the expression of Bax protein was lower than that in the Agiophyllum Oligo Saccharides group (P < 0.05), but still higher than that in the model group 
(P < 0.05). (4) Compared with the model group and the Agiophyllum Oligo Saccharides group, the protein expressions of TLR4, MyD88 and p-NF-κBp65/NF-κBp65 decreased (P < 0.05), whereas the protein expressions of IκBα increased (P < 0.05) in the Bay 11-7082 group. To conclude, Agiophyllum Oligo Saccharides could inhibit inflammation of mouse synovial cells and promote apoptosis of synovial cells with inflammation, and the mechanisms may be correlated with regulating the TLR4/NF-κB signaling pathway. 

Key words: osteoarthritis, Agiophyllum Oligo Saccharides, mouse synovial cells, inflammation, apoptosis, signaling pathway, lipopolysaccharide, Bay 11-7082, engineered tissue construction