Genomic and nongenomic signaling induced by 1α,25(OH)2-vitamin D3 promotes the recovery of amyloid-β phagocytosis by Alzheimer's disease macrophages.
Level 5 - mechanism / opinion, no new human data
In vitro mechanistic laboratory study using isolated human macrophages and PBMCs.
PubMed 22207005 · doi:10.3233/JAD-2012-110560
What was done
The authors investigated the cellular and molecular mechanisms by which 1α,25(OH)2-vitamin D3 (1,25D3) and curcuminoid derivatives (bisdemethoxycurcumin [BDC] and analog C180) restore amyloid-β (Aβ42) phagocytosis in macrophages and peripheral blood mononuclear cells (PBMCs) from Type I and Type II Alzheimer's disease (AD) patients. They analyzed chloride channel (ClC-3) currents, ClC-3 and vitamin D receptor (VDR) mRNA expression, pathway inhibition (using chloride blocker IP4 and MEK1/2 inhibitor U0126), and VDR helix stabilization via hydrogen/deuterium exchange mass spectrometry and computational modeling.
What was found
The abstract reports molecular mechanisms and directions of effect without numerical values: - 1,25D3 potentiated ClC-3 currents in both Type I and Type II AD macrophages, whereas curcumin only potentiated currents in Type I cells. - 1,25D3 upregulated ClC-3 mRNA in Type II PBMCs, while both 1,25D3 and C180 upregulated VDR mRNA (which was repressed by Aβ42 in Type II PBMCs). - 1,25D3-stimulated Aβ42 phagocytosis was attenuated by the ClC-3 blocker IP4 in both patient subtypes, and by the MEK1/2 inhibitor U0126 selectively in Type II macrophages. - 1,25D3 and curcuminoids exhibited distinct structural stabilization of VDR helices involved in gene transcription.
Why it matters
The findings detail specific genomic and nongenomic VDR-dependent signaling pathways that could explain how vitamin D3 and curcuminoids influence innate immune clearance of amyloid-β in Alzheimer's disease.
Limits
The study is entirely in vitro and ex vivo; no in vivo human outcomes or clinical trials were evaluated. The abstract reports no sample size, patient baseline characteristics, or quantitative effect sizes and confidence intervals.
Cited by
- partial Curcumin combined with vitamin D decreases amyloid plaques associated with Alzheimer's disease.