IL1B and Alzheimer disease: Notably, when the two most representative cytokines of AD, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNFα) [18], were analyzed, we found a statistically significant 30% decrease in hippocampal TNFα expression (Fig. 3c, d) between MSC-CS- and PBS-treated APP/PS1, whereas the expression of IL-1β was unchanged (Fig. 3f, g).