Abstract
Vitamin D is a secosteroid hormone that shares a synthetic pathway with cholesterol. ApoE, which is involved in the transport of cholesterol, is the most significant genetic risk factor for sporadic Alzheimer's disease (AD). Surprisingly, recent studies have indicated the presence of an evolutionary juncture between these two molecules. To demonstrate this possible relationship, we investigated serum levels of 25-hydroxyvitamin-D3 (25OHD) in patients with early onset-AD (EOAD; n:22), late onset-AD (LOAD; n:72), mild cognitive impairment (MCI; n:32) and in healthy subjects (n:70). We then analyzed the correlation between 25OHD and cytokines, BDNF and Hsp90 with respect to ApoE alleles, as these molecules were investigated in our previous studies. The LOAD patients had low levels of 25OHD, but these low levels originated only from ApoEɛ4 non-carrier patients. Negative correlations were observed between serum 25OHD and TNFα, IL-1β or IL-6 levels in healthy subjects or MCI patients, but these same correlations were positive in LOAD patients. ApoE alleles indicated that these positive correlations exist only in ɛ4 carrier LOAD patients. Consequently, our results indicate that vitamin D deficiency presents a greater risk for ApoEɛ4 non-carrier AD patients than for ɛ4 carriers. Therefore, it might be beneficial to monitor the vitamin D status of ApoEɛ4 allele non-carrier AD patients.
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