Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
Department of Physiology, University of Kentucky College of Medicine, 780 Rose Street, Lexington, KY 40536, USA.
Neurobiol Dis. 2023 Aug;184:106213. doi: 10.1016/j.nbd.2023.106213. Epub 2023 Jun 25.
Female biased pathology and cognitive decline in Alzheimer's disease (AD) have been consistently observed with unclear underlying mechanisms. Although brain sphingolipid ceramide is elevated in AD patients, whether and how ceramide may contribute to sex-specific differences in amyloid pathology is unknown. Here we investigated the sex-specific impact of chronic pharmacological inhibition of neutral sphingomyelinase (nSMase), a key enzyme responsible for ceramide metabolism, on in vivo neuron-derived exosome dynamics, Aβ plaque load, and cognitive function in the APP knock-in (APP NL-F) AD mouse model. Our results found sex-specific increase of cortical C20:0 ceramide and brain exosome levels only in APP NL-F but not in age-matched WT mice. Although nSMase inhibition similarly blocks exosome spreading in male and female mice, significantly reduced amyloid pathology was mostly observed in cortex and hippocampus of female APP NL-F mice with only modest effect found on male APP NL-F mice. Consistently, T maze test to examine spatial working memory revealed a female-specific reduction in spontaneous alternation rate in APP NL-F mice, which was fully reversed with chronic nSMase inhibition. Together, our results suggest that disease induced changes in ceramide and exosome pathways contribute to the progression of female-specific amyloid pathology in APP NL-F AD models.
女性偏倚的病理学和阿尔茨海默病(AD)认知能力下降一直存在,但潜在机制尚不清楚。尽管 AD 患者脑中神经酰胺水平升高,但神经酰胺是否以及如何导致淀粉样蛋白病理学的性别特异性差异尚不清楚。本研究通过慢性抑制中性鞘磷脂酶(nSMase)研究了其对 APP 基因敲入(APP NL-F)AD 小鼠模型中体内神经元衍生外泌体动力学、Aβ斑块负荷和认知功能的性别特异性影响。nSMase 是神经酰胺代谢的关键酶,研究结果发现,只有 APP NL-F 而非年龄匹配的 WT 小鼠的皮质 C20:0 神经酰胺和脑外泌体水平出现性别特异性增加。尽管 nSMase 抑制同样会阻止雄性和雌性小鼠的外泌体扩散,但在雌性 APP NL-F 小鼠中观察到的淀粉样蛋白病理学显著减少,而在雄性 APP NL-F 小鼠中仅观察到适度的效果。同样,用于检查空间工作记忆的 T 迷宫测试显示,APP NL-F 小鼠的自发交替率出现了性别特异性降低,而慢性 nSMase 抑制可完全逆转这一现象。综上所述,研究结果表明,疾病诱导的神经酰胺和外泌体途径变化可能导致 APP NL-F AD 模型中女性特有的淀粉样蛋白病理学进展。