|MERRIMAN, KATHRYN - University Of Florida|
|KWEH, MERCEDES - University Of Florida|
|POWELL, JESSICA - University Of Florida|
|NELSON, CORWIN - University Of Florida|
Submitted to: The Journal of Steroid Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2015
Publication Date: 8/5/2015
Citation: Merriman, K.E., Kweh, M.F., Powell, J.L., Lippolis, J.D., Nelson, C.D. 2015. Multiple ß-defensin genes are upregulated by the vitamin D pathway in cattle. The Journal of Steroid Biochemistry and Molecular Biology. doi: 10.1016/j.jsbmb.2015.08.002.
Interpretive Summary: We have discovered that the active form of vitamin D initiates an immune response in cattle that includes multiple antimicrobial genes called ß-defensins. Our findings here, along with previous reports showing that vitamin D can alter expression genes and slow bacterial infection in the mammary gland. The knowledge gained from further studies in cattle should also lead to a better understanding of the vitamin D mechanisms and requirements important for optimal function of the immune system in animals and humans.
Technical Abstract: Experimental models of bacterial and viral infections in cattle have suggested vitamin D has a role in innate immunity of cattle. The intracrine vitamin D pathway of bovine macrophages, however, has only been shown to activate a nitric oxide-mediated defense mechanism, as opposed to cathelicidin and ß-defensin antimicrobial peptides in human macrophages. In this study we have investigated the actions of 1,25-dihydroxyvitamin D3 (1,25D) on a cluster of eleven bovine ß-defensin genes on the basis of RNAseq data indicating they were targets of 1,25D in cattle. Treatment of bovine monocyte cultures with 1,25D (10 nM, 18 h) in the absence and presence of LPS stimulation increased the expression of bovine ß-defensin 3 (BNBD3), BNBD4, BNBD6, BNBD7, and BNBD10 genes 5 to 10-fold compared to control (P < 0.05). Treatment of lipopolysaccharide (LPS)-stimulated monocytes with 0-100 ng/mL 25-hydroxyvitamin D3 also increased BNBD3, BNBD4, BNBD7, and BNBD10 in a dosedependent manner. Treatment of monocytes with the protein translation inhibitor, cycloheximide, however, blocked upregulation of the ß-defensins in response to 1,25D suggesting the ß-defensins in cattle are not direct targets of the vitamin D receptor. Furthermore, preliminary investigation of vitamin D's contribution to ß-defensin expression in vivo revealed that intramammary 1,25D treatment of lactating cows increased BNBD7 expression in mammary macrophages. In conclusion, our data demonstrate that multiple ß-defensin genes are upregulated by 1,25D in cattle, providing further indication that vitamin D contributes to bovine innate immunity.