Short communication: Vitamin D status and responses in dairy cows naturally infected with Mycobacterium avium ssp. paratuberculosis

Abstract

Serum samples were obtained from Holstein dairy control cows and cows naturally infected with Mycobacterium avium ssp. paratuberculosis (MAP) to evaluate the effects of disease status on serum 25-hydroxyvitamin D 3 (25OHD 3 ) levels. Disease status was stratified for infected cows into asymptomatic, subclinical infection (n = 25), and cows demonstrating clinical signs (n = 20), along with noninfected control (n = 12) cows for comparison. In addition, portions of the ileocecal valve were taken from a subsample of cows (n = 5 per treatment group) at necropsy and processed for RNA sequencing gene transcription studies. Genes associated with vitamin D metabolism were queried to determine any association between infection and gene expression. Serum 25OHD 3 levels were significantly lower in cows in the clinical stage of disease compared with either cows in the subclinical stage and noninfected control cows. Differential expression for genes associated with the vitamin D pathway such as CYP27A1, CYP27B1, vitamin D-binding protein (DBP), and IFNG was dependent upon infection status. An upregulation of CYP27A1 was noted for cows in subclinical status, whereas CYP27B1 expression was enhanced for clinical cows. Increased expression of vitamin D-binding protein was observed for infected cattle, regardless of infection status. In summary, decreases in circulating 25OHD 3 for animals with clinical disease may suggest that these cows have reduced innate immune responses, thereby influencing the ability of animals to fight infection.

RNA-Seq analysis of ileocecal valve and peripheral blood from Holstein cattle infected with Mycobacterium avium subsp. paratuberculosis revealed dysregulation of the CXCL8/IL8 signaling pathway

“…In agreement with these findings, recent reports have demonstrated that MAP is able to manipulate the host lipid metabolism and accumulate cholesterol within macrophages which might favor MAP persistence 49 . In addition, decreases in serum 25-hydroxyvitamin D 3 (25OHD 3 ) levels were significantly lower in cows in the clinical stage of disease compared with either cows in the subclinical stage and non-infected control cows 50 . It is generally accepted that cattle in advanced stages of MAP infection are unable to metabolize and absorb vitamin D 3 across the intestinal wall, and therefore suffer from weight loss and cachexia.…”

Exogenous Vitamin D3 Modulates Response of Bovine Macrophages to Mycobacterium avium subsp. paratuberculosis Infection and Is Dependent Upon Stage of Johne’s Disease

“…Little work has been done characterizing links between vitamin D 3 status and vitamin D 3 treatment on immune responses from cattle infected with MAP. Cows in the clinical stage of infection have been previously reported to have significantly reduced serum 25(OH)D 3 levels, possibly due to inhibition of dietary vitamin D 3 absorption from pathologic intestinal mucosal thickening ( Stabel et al., 2019 ; Wherry et al, 2021).…”

Phenotypes of macrophages present in the intestine are impacted by stage of disease in cattle naturally infected with Mycobacterium avium subsp. paratuberculosis

“…Infected animals were naturally infected with MAP and were classified into the subclinical and clinical categories based upon fecal shedding, determined by fecal culture and PCR, and clinical signs [18]. Infected and control cows were housed separately at the NADC and tested at least biannually, with endpoint testing just prior to necropsy [19]. Cows were housed in the dairy cattle barn onsite with access to freestall and pasture areas for resting.…”