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

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.

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.

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.

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