ARS | Publication request: Regulation of thymosin beta 4 in chicken macrophages by toll like receptor activation

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 11, 2008
Publication Date: N/A

Technical Abstract: Thymosin beta 4 (TB4) is a 5kDa peptide that binds to the cytoskeletal protein actin and regulates cell motility. At the extracellular level it also promotes chemotaxis, wound healing and angiogenesis. However, the mechanism responsible for the regulation of TB4 production and its secretion to the extracellular environment is still not understood. Previously, we found the chicken macrophages rich in TB4. Since these cells play key roles in the process of wound healing and angiogenesis, we hypothesized that the activation of macrophages through appropriate Toll like receptors (TLR) may promote TB4 synthesis and its secretion. To test the hypothesis, we treated a chicken macrophage cell line with different TLR ligands and studied their effects on TB4 gene expression and its secretion at 6 and 24 h time points. Real time PCR was used for gene expression studies and stable isotope labeling with amino acids in the cell culture (SILAC) followed by mass spectrometric analysis for its secretion. Although certain TLR activation induced the expression of several reference genes, the TB4 expression was not affected. SILAC data showed these TLR activations causing a down regulation of cellular TB4 content along with its corresponding increase in cell culture media at 24 h. These modulations were not seen at 6 h time point. The elevated levels of TB4 in the culture medium at 24 h appears to be associated with cell death as determined by an increase in the percentage of trypan blue positive cells. These results imply that TB4 in the wound fluid perhaps originate from dead cells which then facilitate wound healing.