Identification and characterization of proteins and peptides associated with poultry metabolic skeletal diseases.

摘要

Biomarkers are molecular signals indicative of physiopathological changes. In animal agriculture, biomarkers can be useful to monitor livestock health, implement genetic selection, and understand disease mechanisms. Our research focuses on identifying the proteomic and peptidomic changes in cartilage tissue and the serum of broiler breeders with skeletal problems which cause lameness in poultry. The studies were done to understand the disease mechanisms and to identify possible biomarkers for tibial dyschondroplasia (TD) and femoral head separation (FHS), the two common poultry leg problems. The studies were done using both naturally occurring and experimentally induced disease models. Additionally the in vitro effect of thiram, a pesticide which induces TD was studied using chondrocytes in culture to understand the disease mechanism. Serum proteins and peptides were analyzed for biomarkers. Proteins and peptides were analyzed by 2-D gel electrophoresis and mass spectrometry. Comparisons between normal and diseased tissues showed down-regulation in several proteins associated with energy metabolism, tissue integrity and signal transduction, suggesting the compromise of chondrocyte functions that possibly prevent their differentiation to bone. To identify disease associated biomarkers, we analyzed serum from normal and disease affected chickens which showed a protein named Apolipoprotein A-1 down-regulated in birds with FHS and immunoglobulins elevated in birds with TD. The elevated level of immunoglobulins in TD is the first observation which suggests an onset of immune activation in TD. Serum peptide analysis revealed an elevation in the levels of type XI collagen fragment in TD but no changes in serum peptides in FHS. Type XI collagen is a cartilage specific extracellular matrix protein that is responsible for the organizational integrity of growth plate that could be a surrogate marker for TD. The studies reported here not only show the results obtained using both naturally occurring and experimentally induced diseased tissues, and sera obtained from these birds but also highlight the complexities and difficulties of studying skeletal proteomics and problems inherent in analyzing blood to prospect for biomarkers associated with these problems.