Submitted to: Journal of Leukocyte Biology
Publication Type: Abstract Only
Publication Acceptance Date: 8/31/2005
Publication Date: 9/29/2005
Citation: Eicher, S.D., Cary, D.C. 2005. Modulation of toll-like receptors 2 and 4 and interleukin-1 rna expression of blood leukocytes by beta-glucan and ascorbic acid in neonatal calves. Journal of Leukocyte Biology. 78(1):67.
Technical Abstract: Beta-glucan and ascorbic acid have been shown to modulate immune functions when fed orally. The objective of this study was to examine the innate immune response in peripheral blood and tissues, after calves were fed beta-glucan with or without ascorbic acid for 21 d. Twenty-five bull calves were placed into one of four treatment groups at 3 d-of-age, experimental day 0 (d 0). The control treatment (CTL), received unsupplemented milk replacer for 21 d (n=5); treatment 2 (BG3), received unsupplemented milk replacer for 17 d and a fluorescently-labeled beta-glucan (0.9mg/d), in milk replacer on d 18-20 (n=5); treatment 3 (BG20), received beta-glucan (0.9mg/d) for 17 d and a fluorescently-labeled beta-glucan (0.9mg/d) on d 18-20 (n=10); and treatment 4 (BGA), received beta-glucan (0.9mg/d) plus ascorbic acid (0.5mg/d) for 17 d and a fluorescently-labeled beta-glucan (0.9mg/d) plus ascorbic acid (0.5mg/d) on d 18-20 (n=5). Weekly jugular blood samples were collected at d 0, d 7, d 14, and d 21. All calves were euthanized at d 21, and a portion of the lung, liver, spleen, ileum, jejunum, and mesenteric lymph nodes (MLN) were removed. Blood and tissues were subjected to RNA extraction for real-time RT-PCR analysis for interleukin-1 (IL-1), IL-1 receptor antagonist (Ra), and toll-like receptors (TLR) 2 and 4. A day effect (P < 0.05) was detected for TLR2 . TLR2 RNA expression decreased with age for all treatments. TLR4 RNA expression decreased with age (P < 0.01), but a weak trend for a day by treatment interaction was found (P = 0.11) such that CTL increased expression of TLR4 on d 14 and BG20 expression of TLR4 was greatest on d 7. IL-1 RNA expression showed a treatment by day interaction (P < 0.01). The BGA treatment decreased IL-1 expression with age, but the CTL treatment increased IL-1 expression through d 14, and d 21 returned to d 0 values. BG20 and BGA treatments expression of IL-1 decreased with age. BG3 treatment had greater IL-1 expression on d 7 and 21 compared to d 14. IL1Ra tended (P =0.09) to have a treatment by day effect, because BG20 increased IL-1Ra expression with age, but the BGA treatment decreased IL-1Ra expression with age. The addition of ascorbic acid increased IL-1 and IL-1Ra expression compared to CTL treatment in the ileum (P < 0.05) and decreased IL-1 expression compared to BG3 and BG20 in the lung (P < 0.05). Addition of ascorbic acid also decrease TLR2 expression in the lung compared to CTL , BG3, and BG20 (P < 0.05). Additionally, BGA increased TLR4 expression in the mesenteric lymph nodes compared to the CTL treatment. The addition of ascorbic acid appears to modulate lung tissues differently than intestinal tissues and lymph nodes, but the beta-glucan treatment tended to have variable effects with age. This information further supports the use of yeast cell-wall products with ascorbic acid to enhance health and survival of dairy calves. Mention of trade names or commercial products in this abstract are solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.