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.