Apolipoprotein (apo) E4 isoform, a major risk factor for Alzheimer disease (AD), is more susceptible to proteolysis than apoE2 and apoE3 isoforms. ApoE4 fragments have been found in AD patients' brain. In the present study, we examined the effect of full-length apoE4 and apoE4 fragments apoE4[δ(186-299)] and apoE4[δ(166-299)] on inflammation in human neuroblastoma SK-N-SH and human astrocytoma SW-1783 cells. Western blot and zymography analysis showed that treatment of SK-N-SH cells with apoE4[δ(186-299)], but not full-length apoE4 or the shorter apoE4[δ(166-299)] fragment, leads to increased extracellular levels of matrix metalloproteinase 9 (MMP9) and tissue inhibitor of metalloproteinase 1 (TIMP1). Real-time PCR showed that interleukin (IL)-1β gene expression is also increased in SK-N-SH cells treated with apoE4[δ(186-299)]. Treatment of SK-N-SH cells with IL-1β leads to increased MMP9 and TIMP1 extracellular levels, suggesting that the induction of IL-1β may be the mechanism by which apoE4[δ(186-299)] regulates MMP9 and TIMP1 levels in these cells. In contrast to SK-N-SH cells, treatment of SW-1783 cells with apoE4[δ(186-299)], and to a lesser extent with apoE4, leads to increased TIMP1 extracellular levels without affecting MMP9 levels. Additionally, apoE4[δ(186-299)] leads to decreased IL-10 gene expression in SK-N-SH cells, whereas both apoE4 and apoE4[δ(186-299)] lead to decreased TNFα gene expression without affecting IL-1β and IL-10 gene expression in SW-1783 cells. Overall, our findings indicate that a specific apoE4 fragment (apoE4[δ(186-299)]), with molecular mass similar that of apoE4 fragments detected in AD patients' brain, can influence the level of inflammatory molecules in brain cell lines. It is possible that these phenomena contribute to AD pathogenesis.
|Original language||English (US)|
|Number of pages||12|
|State||Published - May 17 2012|
Bibliographical noteFunding Information:
Funding for this work was provided by the General Secretariat of Research and Technology of Greece (Synergasia 09SYN-12-897 to A.C.) and by the National Institutes of Health ( HL68216 to V.Z.).
- Alzheimer disease
- Apolipoprotein E
- Apolipoprotein E4 fragments
- Matrix metalloproteinase 9