AUTHOR=Wherry Taylor L. T. , Dassanayake Rohana P. , Bannantine John P. , Mooyottu Shankumar , Stabel Judith R. 

TITLE=Vitamin D3 alters macrophage phenotype and endosomal trafficking markers in dairy cattle naturally infected with Mycobacterium avium subsp. paratuberculosis

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.1021657

DOI=10.3389/fcimb.2022.1021657

ISSN=2235-2988

ABSTRACT=<p>Macrophages are important host defense cells in ruminant paratuberculosis (Johne’s Disease; JD), a chronic enteritis caused by <italic>Mycobacterium avium</italic> subsp. <italic>paratuberculosis</italic> (MAP). Classical macrophage functions of pathogen trafficking, degradation, and antigen presentation are interrupted in mycobacterial infection. Immunologic stimulation by 25-hydroxyvitamin D<sub>3</sub> (25(OH)D<sub>3</sub>) and 1,25-dihydroxyvitamin D<sub>3</sub> (1,25(OH)<sub>2</sub>D<sub>3</sub>) enhances bovine macrophage function. The present study aimed to investigate the role of vitamin D<sub>3</sub> on macrophage phenotype and endosomal trafficking of MAP in monocyte-derived macrophages (MDMs) cultured from JD-, JD+ subclinical, and JD+ clinically infected cattle. MDMs were pre-treated 100 ng/ml 25(OH)D<sub>3</sub> or 4 ng/ml 1,25(OH)<sub>2</sub>D<sub>3</sub> and incubated 24 hrs with MAP at 10:1 multiplicity of infection (MOI). <italic>In vitro</italic> MAP infection upregulated pro-inflammatory (M1) CD80 and downregulated resolution/repair (M2) CD163. Vitamin D<sub>3</sub> generally decreased CD80 and increased CD163 expression. Furthermore, early endosomal marker Rab5 was upregulated 140× across all stages of paratuberculosis infection following <italic>in vitro</italic> MAP infection; however, Rab5 was reduced in MAP-activated MDMs from JD+ subclinical and JD+ clinical cows compared to healthy controls. Rab7 expression decreased in control and clinical cows following MDM infection with MAP. Both forms of vitamin D<sub>3</sub> reduced Rab5 expression in infected MDMs from JD- control cows, while 1,25(OH)<sub>2</sub>D<sub>3</sub> decreased Rab7 expression in JD- and JD+ subclinical animals regardless of MAP infection <italic>in vitro</italic>. Vitamin D<sub>3</sub> promoted phagocytosis in MDMs from JD- and JD+ clinical cows treated with either vitamin D<sub>3</sub> analog. Results from this study show exogenous vitamin D<sub>3</sub> influences macrophage M1/M2 polarization and Rab GTPase expression within MDM culture.</p>