TNF and Parkinson disease: The serum MyD88, NF‐κB, and TNF‐α levels of the healthy controls were 518.2 ± 63.4, 985.3 ± 114.6, and 207.3 ± 27.4, respectively, which were significantly higher than those of the patients with PD (879.2 ± 85.3, 1453.4 ± 184.6, and 415.3 ± 46.7, respectively; p < .05), suggesting that HMGB1–TLR4 axis downstream signaling was positively associated with the high expression of the HMGB1–TLR4 axis (Figure 3).