[TLR2 blockade reduces TNF-α expression induced by β2GP1/anti-β2GP1 complex in mouse peritoneal macrophages].

Objective: To investigate the role of Toll-like receptor 2 (TLR2) in β2-glycoprotein 1/anti-β2-glycoprotein 1 (β2GP1/anti-β2GP1)-mediated tumor necrosis factor α (TNF-α) expression in mouse peritoneal macrophages.

Methods: The peritoneal macrophages from BALB/c mice were treated with β2GP1/anti-β2GP1 complex, agonist of TLR2 (Pam3CSK4) and agonist of TLR4 [lipopolysaccharide (LPS)], inhibitor of TLR2 [monoclonal IgG to mouse TLR2 (anti-mTLR2-IgG)] and inhibitor of TLR4 (TAK-242) in vitro. The mRNA level of TNF-α in the peritoneal macrophages was tested by real-time quantitative PCR, the protein expression of TNF-α was detected by Western blotting and immunofluorescence cytochemistry, and the expression of TLR2 on the surface of the peritoneal macrophages was assessed by flow cytometry.

Results: The mRNA and protein expression of TNF-α was significantly enhanced in mouse peritoneal macrophages treated with β2GP1/anti-β2GP1 complex, Pam3CSK4 and LPS. Anti-mTLR2-IgG could inhibit the effects of the above stimuli on TNF-α expression, but its effects were weaker than those of TAK-242. Meanwhile, the combination of anti-mTLR2-IgG and TAK-242 did not show much stronger inhibitory effects. Flow cytometry analysis showed that expression of TLR2 was enhanced by β2GP1/anti-β2GP1 complex, Pam3CSK4 and LPS in mouse peritoneal macrophages. However, anti-mTLR2-IgG, or TAK-242, or combination of both could not inhibit TLR2 expression in macrophages.

Conclusion: Both TLR4 and TLR2 could increase the stimulating effect of β2GP1/anti-β2GP1 complex on the expression of TNF-α in mouse peritoneal macrophages.