Dietary cis-9, trans-11-conjugated linoleic acid reduces amyloid β-protein accumulation and upregulates anti-inflammatory cytokines in an Alzheimer’s disease mouse model

Conjugated linoleic acid (CLA) is an isomer of linoleic acid (LA). The predominant dietary CLA is cis -9, trans -11-CLA ( c -9, t -11-CLA), which constitutes up to ~ 90% of total CLA and is thought to be responsible for the positive health benefits associated with CLA. However, the effects of c -9, t -11-CLA on Alzheimer’s disease (AD) remain to be elucidated. In this study, we investigated the effect of dietary intake of c -9, t -11-CLA on the pathogenesis of an AD mouse model. We found that c -9, t -11-CLA diet-fed AD model mice significantly exhibited (1) a decrease in amyloid-β protein (Aβ) levels in the hippocampus, (2) an increase in the number of microglia, and (3) an increase in the number of astrocytes expressing the anti-inflammatory cytokines, interleukin-10 and 19 (IL-10, IL-19), with no change in the total number of astrocytes. In addition, liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatographic analysis revealed that the levels of lysophosphatidylcholine (LPC) containing c -9, t -11-CLA (CLA-LPC) and free c -9, t -11-CLA were significantly increased in the brain of c -9, t -11-CLA diet-fed mice. Thus, dietary c -9, t -11-CLA entered the brain and appeared to exhibit beneficial effects on AD, including a decrease in Aβ levels and suppression of inflammation.