Impact of the mare colostral immunoglobulins on the expression of TLR3, TLR4 and TLR7 in foals.

Background: Colostrum contains substances such as hormones, enzymes, polyamides, nucleic acid derivatives and amino acid derivatives. Their range also includes immunomodulating substances, proline-rich polypeptides (PRP), immunoglobulins as well as bacteriostatic compounds. Based on its biological properties as well as the influence of Toll-like receptors on immune response traits of farm animals and humans, we hypothesised that gene expression for Toll-like receptors in foals is dependent on the quality of colostrum. Objectives: The aim of the study was to evaluate the impact of the quality of colostrum on the level of expression of selected Toll-like receptor genes (TLR3, TLR4, and TLR7). Study design: The experiments were conducted on 25 foals Polis Pony breed. Blood samples were collected up to 30 days of age according to the following scheme: before first suckling, at the 1st, 3rd, 5th, 10th, 20th, and 30th, day of age. Colostrum was obtained before the first suckling, 24 hr and 3 days after the delivery. Methods: Gene expression analyses were performed on Illumina Eco using a commercial kit TaqMan®MGB probes. The quality of colostrum was assessed using an optical refractometer. Total immunoglobulin level was calculated from the spectrophotometric method. Immunoglobulin G level were measured using ELISA assay Microplate Reader using 96-well plates coated with monoclonal antibodies against equine IgG. Results: The quality of colostrum significantly correlated with TLR4 and TLR7 expression. Foals that ingested colostrum with low immunoglobulin content displayed higher level of TLR4 gene expression, while in case of TLR7 the opposite trend was shown. Main limitations: It is likely that fat and the proportion of individual fatty acids in colostrum affect the action of membrane Toll-like receptors Conclusions: The expression of genes for TLR3 and TLR4 in peripheral blood is dependent on immunoglobulin concentration in mammary gland secretion suckled by foals.