Aberrant oligodendroglial LDL receptor orchestrates demyelination in chronic cerebral ischemia

Oligodendrocytes express low-density lipoprotein receptor (LDLR) to endocytose cholesterol for the maintenance of adulthood myelination. However, the potential role of LDLR in chronic cerebral ischemia-related demyelination remains unclear. We used bilateral carotid artery stenosis (BCAS) to induce sustained cerebral ischemia in mice. This hypoxic-ischemic injury caused a remarkable decrease in oligodendroglial LDLR, with impaired oligodendroglial differentiation and survival. Oligodendroglial cholesterol levels, however, remained unchanged. Mouse miR-344e-3p and the human homolog miR-410-3p, 2 miRNAs directly targeting Ldlr, were identified in experimental and clinical leukoaraiosis and were thus implicated in the LDLR reduction. Lentiviral delivery of LDLR ameliorated demyelination following chronic cerebral ischemia. By contrast, Ldlr-/- mice displayed inadequate myelination in the corpus callosum. Ldlr-/- oligodendrocyte progenitor cells (OPCs) exhibited reduced ability to differentiate and myelinate axons in vitro. Transplantation with Ldlr-/- OPCs could not rescue the BCAS-induced demyelination. Such LDLR-dependent myelin restoration might involve a physical interaction of the Asn-Pro-Val-Tyr (NPVY) motif with the phosphotyrosine binding domain of Shc, which subsequently activated the MEK/ERK pathway. Together, our findings demonstrate that the aberrant oligodendroglial LDLR in chronic cerebral ischemia impairs myelination through intracellular signal transduction. Preservation of oligodendroglial LDLR may provide a promising approach to treat ischemic demyelination.

Statins decrease the risk of stroke in individuals with heterozygous familial hypercholesterolemia: A systematic review and meta-analysis

BACKGROUND

Familial hypercholesterolemia (FH) is undoubtedly associated with premature coronary heart disease, but it is debatable whether FH increases the risk for stroke.

OBJECTIVE

To meta-analyze available evidence regarding the incidence of stroke in individuals with heterozygous (He) FH.

METHODS

We conducted a systematic review and a meta-analysis of epidemiological studies, including English-language publications until June 2015; four observational studies, with 3374 participants with HeFH, were included in the analysis. Cerebrovascular disease comprised of ischemic stroke or transient ischemic attack. Since studies did not include any control subjects, the corresponding general population of the same reference area and period of time for each HeFH study served as control group. Analyses were performed according to the period of time during which the studies were conducted: prestatin and statin era (before and after 1987 when lovastatin was launched).

RESULTS

In the prestatin era, individuals with HeFH exhibited a higher risk for stroke compared with the general population [odds ratio (OR) = 7.658, 95% confidence interval (CI): 6.059-9.678, p < 0.01]. In contrast, FH subjects had a lower odds for stroke following the generalization of statin therapy (OR = 0.251, 95% CI: 0.176-0.358, p < 0.01).

CONCLUSIONS

Taking into account the small number of studies and methodological issues, HeFH was associated with a higher risk of cerebrovascular disease compared with the general population in the prestatin era, which was significantly reduced after the introduction of statin therapy.