Megasun

Fighting infections with vitamin D.

Vitamin D fights infectionTwo related pathways within the skin and circulating monocytes-macrophages are highlighted.
Sunlight converts 7-dehydrocholesterol (7-DHC) in the skin to vitamin D3, which is converted successively to 25-hydroxy-D3 (25-D3) and then to 1,25-dihydroxy-D3 (1,25-D3) within keratinocytes.
Sunlight also induces expression of the vitamin D receptor (VDR). 1,25-D3 and the VDR then together induce the expression of the gene encoding the human antimicrobial peptide LL-37.
Vitamin D3 enters the systemic circulation and is converted to 25-D3 by the liver.
Circulating monocytes are activated by TLR2/1 agonists present on specific microbes.
The genes encoding VDR and CYP 27B1 are induced.
CYP27B1 converts 25-D3 from the circulation to 1,25-D3, joins with the VDR and activates the gene encoding LL-37, leading to an increase in cellular LL-37 and enhanced microbicidal activity of the phagocyte.

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