IL6 and Anxiety: For example, in an open field test, Kinsey et al. [11] demonstrated that after social defeat, middle-aged subordinate mice (14 months old) showed increased anxiety-like behavior and enhanced inflammatory responses including increased interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) levels compared with young subordinates (2 months old), suggesting that aging exacerbates vulnerability to social stress in mice [11].