IL6 and persistent fetal circulation syndrome: The serum levels of HMGB1, TNF-α, and IL-6 at PPHN onset and at PPHN alleviation were 33.19 ± 9.45 vs. 13.42 ± 2.14 ng/mL, 40.41 ± 14.3 vs. 15.12 ± 2.45 pg/mL, and 32.98 ± 13.42 vs. 11.75 ± 2.77 pg/mL, respectively, and all differences were statistically significant (P < 0.05; Table 2).