Neuroinflammatory and Amyloidogenic Activities of IL-32β in Alzheimer's Disease.

Interleukin (IL)-32β can act as either pro-inflammatory or anti-inflammatory cytokines with being dependent on the status of disease development. Herein, we investigated whether IL-32β overexpression changes cytokine levels and affects amyloid-beta (Aβ)-induced pro-inflammation in the brain. IL-32β transgenic (Tg) mice and non-Tg mice were intracerebroventricularly infused with Aβ1-42 once a day for 14 days, and then cognitive function was assessed by the Morris water maze test and passive avoidance test. Our data showed that IL-32β Tg mice increased memory impairment, glia activation, amyloidogenesis, and neuroinflammation. The expression of glial fibrillary acid protein (GFAP), Iba1, and β-secretase 1 (BACE1) in the cortex and hippocampus was much higher in the Aβ1-42-infused IL-32β Tg mice brain. The activation of signal transducer and activator of transcription 3 (STAT3) and nuclear factor-kappa B (NF-κB) was much higher in Aβ1-42-infused IL-32β Tg mice brain. We also found that cytokines including IP-10, GM-CSF, JE, IL-13, and interferone-inducible T cell α chemoattractant (I-TAC) were elevated in Aβ1-42-infused IL-32β Tg mice brain. These results suggest that IL-32β could activate NF-κB and STAT3, and thus affect neuroinflammation as well as amyloidogenesis, leading to worsening memory impairment.