Figure 5

IL-37 inhibits NF-κB activation induced by stimulation of TLR2 and TLR4. (A) AVICs were treated with LPS (0.2 µg/mL) or Pam3CSK4 (0.1 µg/mL) for 1–8 h in the presence and absence of IL-37 (1.0 ng/mL). NF-κB p65 phosphorylation was examined using immunoblotting, and NF-κB DNA-binding activity at 4 h was assessed using enzyme-linked immunosorbent assay. IL-37 reduced NF-κB phosphorylation induced by LPS and abrogated NF-κB phosphorylation induced by PAM3CSK4. The experiments were repeated using three cell isolates from distinct donor valves. IL-37 also reduced NF-κB DNA-binding activity in cells exposed to LPS and abrogated the increase in NF-κB DNA-binding activity in cells exposed to Pam3CSK4. Data are mean ± SE. n = 5 experiments using cell isolates from distinct donor valves; *P <0.05 versus control; #P <0.05 versus LPS alone or Pam3CSK4 alone. (B) AVICs were treated with IL-18Rα-neutralizing antibody (2.65 µg/mL) prior to treatment with IL-37 (1.0 ng/mL). Neutralization of IL-18Rα abolished the effect of IL-37 on NF-κB phosphorylation examined at 4 h after stimulation with LPS or Pam3CSK4. The experiments were repeated three times using cell isolates from distinct donor valves.