1,25-Dihydroxy Vitamin D

Area of Science:

• Neuroimmunology
• Neurodegenerative Diseases
• Molecular Biology

Background:

• Alzheimer's disease (AD) is characterized by dementia and amyloid-beta (Aβ) accumulation.
• Microglia exacerbate AD pathology by producing inflammatory cytokines in response to Aβ.

Purpose of the Study:

• To investigate the immunomodulatory effects of 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) on Aβ-induced microglial activation.
• To determine the role of TREM2 in mediating these effects.

Main Methods:

• HMO6 cells were treated with Aβ42 with or without 1,25(OH)2D3.
• Expression of cytokines, M1/M2 markers, TLRs, and TREM2 was analyzed.
• Aβ uptake was quantified.

Main Results:

• 1,25(OH)2D3 suppressed proinflammatory cytokines (TNF-α, IL-1β, IL-6) and M1 markers (CD86, iNOS).
• It increased anti-inflammatory cytokines (IL-4, IL-10, CCL17) and M2 markers (CD206, Arg-1).
• 1,25(OH)2D3 enhanced TREM2 expression and Aβ uptake, which was TREM2-dependent.

Conclusions:

• 1,25-dihydroxy vitamin D3 exhibits immunomodulatory effects against Aβ pathology in Alzheimer's disease.
• It promotes M2 microglial polarization and enhances Aβ uptake via a TREM2-dependent mechanism.