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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #358728

Research Project: Characterization of Antigens, Virulence Markers, and Host Immunity in the Pathogenesis of Johne’s Disease

Location: Infectious Bacterial Diseases Research

Title: Effects of vitamin D3 on macrophages from cows naturally infected with Mycobacterium avium subsp. paratuberculosis

Author
item WHERRY, T - Iowa State University
item HOSTETTER, J - Iowa State University
item Bannantine, John
item Reinhardt, Timothy - Tim
item Stabel, Judith

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Mycobacterium avium subsp. paratuberculosis (MAP) is an intracellular pathogen that causes chronic enteritis (Johne’s Disease) in ruminants. Upon phagocytosis, MAP can impair macrophage function and persist within the cell during asymptomatic early infection. Clinical disease is associated with an increased burden of MAP due to its uncontrolled replication within the macrophage. Fecal shedding of the bacterium is also observed at this stage. Key events of this change in macrophage function are not well defined. This study aimed to elucidate the effects of exogenous vitamin D3 on killing of MAP by monocyte-derived macrophages (MDMs) from naturally infected dairy cattle. Peripheral blood mononuclear cells (PBMCs) were isolated from 24 Holstein dairy cows and cultured for 5-6 days to obtain MDMs. Cells were washed and adherent macrophages were treated with 100 ng/ml 25-hydroxyvitamin D3 [25(OH)D3] on day 5 for 24 hours or 4 ng/ml 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on day 6 for 4-6 hours. Macrophages were infected for 24 hours at a 10:1 MOI. Immunocytochemistry (ICC) labeling was performed using an in-house polyclonal a-MAP antibody and the BacLight Live/Dead kit, containing propidium iodide and SYTO9 dyes. Fluorescent surface area (SA) of live and dead phagocytized MAP was collected using confocal microscopy and Nikon imaging software. MDMs from clinical cows treated with 25(OH)D3 or 1,25(OH)2D3 both demonstrated a significant increase in phagocytosis and killing of MAP in comparison to untreated clinical cow MDMs and control cow MDMs treated with 25(OH)D3 or 1,25(OH)2D3. In addition, a significant decrease in phagocytosis and killing of MAP was observed in the subclinical group when compared to control and clinical cows, irrespective of exogenous vitamin D3 treatment. These data present evidence of vitamin D3 having immunomodulatory effects on clinical cow macrophage function in the presence of MAP in vitro. This could be a result of altered receptor and cytokine expression profiles, with both severity of disease state and vitamin D3 playing an important role.