OBJECTIVE

To investigate the biological characteristics and effect of TNF-alpha binding peptide (TBP) and TNFR blocking peptide (TRBP) in vitro.

METHODS

The binding specificity of TBP or TRBP was tested by competition experiment using GFP-TNF fusion protein and detected by FCM and fluorescent microscope. The interaction between TBP and TRBP was determined by non-denatured PAGE and the inhibitory effect of TBP and TRBP on TNF-alpha cytotoxicity against U937 was carried out by MTT colorimetry. The effects of TBP and TRBP on the functions of human monocytes activated by TNF-alpha and IFN-gamma in vitro were detected by nitrotetrazolium blue chloride (NBT) reduction assay for evaluating respiratory burst and by RT-PCR for evaluating IL-1beta and IL-8 mRNA transcription.

RESULTS

It was showed that TBP and TRBP was able to block the GFP-TNF binding to the TNFR on the surface of cells and no binding interaction took place between TBP and TRBP. Both TBP and TRBP were able to inhibit the TNF-alpha cytotoxicity against U937 and this inhibitory effect was dose-dependent and the combination of TBP and TRBP (pep.38+X4) was able to inhibit the TNF-alpha cytotoxicity more efficiently than the individual peptide at all tested concentrations. The combination of TBP and TRBP was able to obviously inhibit both respiratory burst of monocytes induced by TNF-alpha and IFN-gamma and transcription level of IL-1beta and IL-8 mRNA induced by TNF-alpha.

CONCLUSIONS

TBP or TRBP can bind with their ligands specifically and don't interact with each other. They can also block the biological activity of the TNF-alpha in vitro, and the combination of TBP and TRBP is able to inhibit the biological activity of the TNF-alpha more efficiently. This research will provide an experimental basis for the clinical treatment of the inflammatory disease.