TNF and isolated hemihyperplasia: The elevation of inflammatory cytokines is compatible with the study by He et al. 36, showing that Wistar rats subjected to a 8-week treatment of severe IH (with an O2 nadir to 5%) had the highest IL-6 and TNF-α levels in blood compared to rats treated with milder IH (an O2 nadir to 7.5%/10%) or normoxia.