Further comparisons between psoriasis patients showed that the serum concentrations of HMGB1, TLR4, IL‐23, and IL‐17A in severe psoriasis patients were all obviously higher than those of moderate psoriasis patients (Table 2 and Figure 2A–D), HMGB1 (t = 9.651, p < .001), TLR4 (z = −5.94, p < .001), IL‐23 (t = 10.94, p < .001), and IL‐17A (z = −3.69, p < .001). Here, TLR4 is linked to psoriasis.