Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/1996
Publication Date: N/A
Interpretive Summary: Johne's disease is a chronic, debilitating intestinal disorder in ruminants characterized by diarrhea, reduced feed intake, weight loss, and death. Little is known about how dietary factors may affect the susceptibility of animals to this disease. The ability to resist infectious pathogens is determined by the efficiency of the immune response. We used a mouse model lto study the effects of vitamin D3 and dietary calcium on the immune response of mice with this disease. We found that mice fed a low calcium diet had a better immune response and were able to resist the pathogen more efficiently. Mice supplemented with vitamin D3 also had improved immune responses compared to control mice. This study shows that dietary supplementation can modulate the immune response to intestinal pathogens.
Technical Abstract: To study the effects of 1,25-dihydroxyvitamin D3 (VD3) and calcium (Ca) on splenocyte cytokine secretion during M. paratuberculosis infection, mice were assigned to the following treatments: 1) noninfected, 2) infected, 3) noninfected/VD3 infusion, 4) infected/VD3 infusion, and 5) infected/low Ca diet (0.15%). Mice in treatments 2, 4 and 5 were inoculated intravenously with 10*8 CFU M. paratuberculosis. At 1, 6 and 12 mos. postinfection, mic in treatments 3 and 4 were implanted subcutaneously with mini-osmotic pumps which delivered 13 ng VD3/day for 14 days. Low dietary Ca treatment was included to elevate endogenous VD3 levels. Splenocytes were isolated from mice at 1, 6, and 12 mos. and stimulated in vitro with medium alone, LPS, ConA, and M. paratuberculosis whole-cell sonicate (MpS). Production of IL- splenocytes isolated from mice fed the low Ca diet compared to control infected mice 1 and 6 mos. after infection. Interleukin-1 and TNF were increased (P<0.05) in splenocytes cultured with LPS and MpS after isolatio from low Ca mice. Mice infused with VD3 had higher (P<0.05) IL-1 secretion after stimulation of splenocytes with LPS and higher (P<0.05) TNF production after incubation with MpS. These results suggest that VD3 and low dietary Ca increase cytokine secretion in mice infected with M. paratuberculosis.