Dietary mixed-oxysterols and 27-Hydroxycholesterol induce cognitive impairment by regulating gut microbiota and miR-144-3p in vivo.

Gut microbiota and microRNAs (miRNAs) have been proved to be intimately involved in dementia. Our previous studies have showed that oxysterols and the subsequent neurotoxic effects contributed to the pathogenesis of cognitive decline. However, the exact mechanism linking dietary oxysterol-induced cognitive changes, gut microbiota, and miRNAs remains elusive. Here, two sets of experiments were conducted on male C57BL/6J mice treated with mixed-oxysterol diet or 27-hydroxycholesterol (27-OHC) combined with antibiotic cocktails and miRNA antagonists. Neurobehavioral tests were conducted to assess learning and memory of mice. 16S ribosomal DNA gene sequencing was performed to evaluate microbial diversity and community composition. Oxysterol levels were detected using HPLC-MS. Western blotting and RT-qPCR were used to detect the expression of the intestinal barrier-related factors. We found that a 0.05% mixed-oxysterol diet altered the gut microbiota, damaged the intestinal barrier, upregulated the expression of miR-144-3p, and resulted in learning and memory impairment, while depleting the gut microbiota with antibiotic cocktails partly alleviated these injuries. Moreover, there were enhanced Aβ deposition, as well as higher 27-OHC and its metabolite in the brain of oxysterols-treated mice, which could be reduced by sterol 27-hydroxylase inhibitor-anastrozole, indicating that 27-OHC might be the key regulator of oxysterol-induced brain pathological changes. Additionally, by antagonizing miR-144-3p, microbiota dysbiosis-related Aβ deposition, oxysterol load, and cognitive decline were significantly ameliorated. Taken together, our study demonstrates that dietary oxysterols impair cognitive function through 27-OHC causing microbiota dysbiosis and intestinal barrier dysfunction, targeting miR-144-3p might be a promising strategy against cognitive impairment.