Submitted to: Veterinary Immunology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2004
Publication Date: 7/25/2004
Citation: Eicher, S.D., Sauter, S.N., Blum, J.W., Hammon, H.M. 2004. TLR2,TLR4, IL-1 and IL-1RA expression from glucocorticoid treated and colostrum fed calves [abstract]. Veterinary Immunology International Symposium. p. 248.
Technical Abstract: Toll-like receptor (TLR) function for cattle has barely begun to be characterized. Because glucocorticoids are a result of acute stressors we investigated the RNA expression of TLR2, TLR4, interleukin (IL)-1, and its receptor antagonist (IL-1Ra) after dexamethasone (a synthetic glucocorticoid) or colostrum feeding in a 2 by 2 factorial arrangement of treatments. Twenty eight calves were assigned to one of four treatments: formula with dexamethasone (FD+), formula without dexamethasone (FD-), colostrum with dexamethasone (CD+) or colostrum without dexamethasone (CD-). Colostrum was saved from d 1, 3, and 5 milkings and the formula that replaced the colostrum was created to have comparable nutrients (but not antibodies) as the corresponding d 1, 3, and 5 colostrum. Dexamethasone was given daily at 30 µg per kg of body weight. On day 5, calves were euthanized and thymus, spleen and lymphonodus prescapularis tissues were collected. RNA was extracted (RNeasy, Qiagen) and subjected to real-time RT-PCR, using Taqman probes, for quantification of TLR2, TLR4, IL-1, and IL-1Ra. The internal standard was GAPDH. All stated differences are at P < 0.05. Spleen IL-1 and its receptor antagonist were expressed similarly. The dexamethasone without colostrum group(FD+) had enhanced RNA expression for IL-1 and IL-1Ra compared with all other treatments. The TLR2 and TLR4 expression was also increased in FD+ calves compared only to FD- and CD- calves. Thymus IL-1, IL-1Ra, and TLR2 expression was greatest for the dexamethasone treated calves compared to both dexamethasone negative groups. However, thymus expression of TLR4 was enhanced only in the FD+ group compared to both dexamethasone negative groups. The CD+ group expression of TLR4 was greater than the CD- group. Lymphnode expression of IL-1, IL-1Ra, TLR2, and TLR4 were greater for the calves given the formula rather than colostrum. In summary, the thymus tissue was not affected by colostrum feeding, but expression of all of the genes was increased 3- to 5-fold by dexamethasone, with the greatest increase of expression being for TLR4. The lymphnode tissues contradicted those effects, having no effects by dexamethasone but without colostrum feeding 2- to 4-fold increases of expression occurred for all genes. The TLR4 gene expression had the greatest enhancement of expression. The spleen tissue expression of the genes was only enhanced (2-fold) by the combination of dexamethasone and no colostrum. In fact the addition of colostrum attenuated the effect of dexamethasone. In conclusion, colostrum feeding and glucocorticoids affected various immune micro-environments differently, probably due to the differences of predominance and maturity of cell populations within those tissues. This demonstrates the importance of colostrum feeding and reduction of stressors for immune regulation of neonatal calves.