Involvement of Huanglian Jiedu Decoction on Microglia with Abnormal Sphingolipid Metabolism in Alzheimer’s Disease

Yi-Yu Qi,1,* Xia Heng,1,* Zeng-Ying Yao,2 Shu-Yue Qu,1 Ping-Yuan Ge,1 Xin Zhao,1 Sai-jia Ni,2 Rui Guo,3 Nian-Yun Yang,1 Qi-Chun Zhang,2 Hua-Xu Zhu1 1Department of Traditional Chinese Medicine Processing and Preparation, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People’s Republic of China; 2Department of Pharmacology, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People’s Republic of China; 3Department of Physiological, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qi-Chun Zhang; Hua-Xu Zhu, Email zhangqichun@njucm.edu.cn; zhuhx@njucm.edu.cnBackground: Abnormal sphingolipid metabolism is closely related to the occurrence and development of Alzheimer’s disease (AD). With heat-clearing and detoxifying effects, Huanglian Jiedu decoction (HLJDD) has been used to treat dementia and improve learning and memory impairments.Purpose: To study the therapeutic effect of HLJDD on AD as it relates to sphingolipid metabolism.Methods: The level of sphingolipids in the brains of APP/PS1 mice and in the supernatant of β-amyloid (Aβ)25– 35-induced BV2 microglia was detected by HPLC-QTOF-MS and HPLC-QTRAP-MS techniques, respectively. The co-expression of ionized calcium-binding adapter molecule 1 (Iba1) and Aβ as well as four enzymes related to sphingolipid metabolism, including serine palmitoyltransferase 2 (SPTLC2), cer synthase 2 (CERS2), sphingomyelin phosphodiesterase 1 (SMPD1), and sphingomyelin synthase 1 (SGMS1), in the brains of APP/PS1 mice were evaluated by immunofluorescence double labelling. In addition, real-time quantitative reverse transcription-polymerase chain reaction was conducted to determine the mRNA expression of SPTLC2, CERS2, SMPD1, SGMS1, galactosylceramidase (GALC), and sphingosine kinase 2 (SPHK2) in Aβ25-35-stimulated BV2 microglia.Results: Abnor