Vitamin D-Dimer: A Possible Biomolecule Modulator in Cytotoxic and Phagocytosis Processes?

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Vitamin D3 complexed to deglycosylated vitamin D binding protein (VitD-dgVDBP) is a novel water-soluble dimeric compound.
• The effects of VitD-dgVDBP on immune cells, including monocytes, macrophages, phagocytosis, apoptosis, and reactive oxygen species (ROS) generation, compared to dgVDBP, were previously unclear.

Purpose of the Study:

• To investigate the impact of VitD-dgVDBP on immune cell functions, specifically macrophage activity, ROS production, and apoptosis.
• To determine the cellular targets and activation pathways of VitD-dgVDBP in normal human lymphocytes (nPBMCs) and malignant prostatic cells.

Main Methods:

• Flow cytometry was employed to assess macrophage activity and superoxide anion radical (O2*−) levels.
• Apoptosis was evaluated in malignant prostatic cells treated with VitD-dgVDBP and dgVDBP.
• The binding of PE-Cy7-labeled VitD-dgVDBP to various immune cell populations (CD markers) and the activation of specific immune cell markers in nPBMCs were analyzed.

Main Results:

• VitD-dgVDBP significantly increased macrophage activity (2.8-fold) while reducing O2*− production (1.8-fold) compared to dgVDBP.
• VitD-dgVDBP induced apoptosis in malignant prostatic cells, activating caspase-3, caspase-9, and cytochrome-C.
• VitD-dgVDBP bound to cytotoxic suppressor cells, monocytes/macrophages, dendritic cells, natural killer cells (CD8+), and helper cells (CD4+), and modulated specific immune cell markers like CD16++, CD45k+, CD85k+, and CD85k+/CD123+.

Conclusions:

• The water-soluble VitD3 form, VitD-dgVDBP, enhances immune cell activity and exhibits potential in inducing apoptosis in malignant prostatic cells.
• VitD-dgVDBP influences cytotoxic suppressor cells through a low radical-dependent CD16 pathway, suggesting a novel therapeutic mechanism.