IL6 and major depressive disorder: Guo et al. [40] reported that EA can downregulate the levels of interleukin-6 (IL-6) and IL-1beta in the hippocampi of depressed rats, demonstrating that the proinflammatory cytokines IL-1beta, IL-6, and TGF-beta mediate the onset of depressive symptoms and further suggesting that EA can potentially alleviate depression through a mechanism involving immunological modulation.