Microglia are the resident immune cells of the central nervous system and are very similar to macrophages. They have been shown to have some involvement in the progression of chronic neurodegenerative inflammatory diseases such as Alzheimer’s or Parkinson’s Disease. Previous studies have shown a correlation between vitamin D deficiency and Alzheimer’s Disease, meaning that to some extent, vitamin D, which mainly functions through the vitamin D receptor (VDR), is involved in the progression of the disease. This study aims to determine whether the deficiency of VDR, through knockdown with siRNA, has any effect on the baseline expression of different inflammatory and anti-inflammatory cytokines and genes.
BV-2 microglial cells were transfected with 75 pmol of VDR siRNA and then incubated in antibiotic-free 10% FBS-containing DMEM for a period of either 24 hours and harvested. Another set of cells were also incubated in the same conditions for 24 hours, after which the medium was replaced with FBS-free DMEM, incubated for another 24 hours and harvested. Cells were then subjected to Reverse Transcription – PCR in order to analyze the mRNA levels of inflammatory and anti-inflammatory markers. At 24 hours, significant decreases were observed in the levels of inducible nitric oxide synthase (iNOS), Arginase 1, CD68, and MHC Class II H-2Aa, as well as a significant increase in Ym1 levels. Similarly, after 48 hours, significant decreases were seen in iNOS, Arginase1, and CD68. On the other hand, there were significant increases in the levels of Fizz1, Ym1, and interleukin-10. These results signify that VDR is indeed an important component in the inflammatory and anti-inflammatory functions of microglia. Future experiments will be carried out to determine the mechanism of how VDR affects microglial function in these aspects.