The in vivo immunomodulatory and synergistic anti-tumor activity of thymosin α1–thymopentin fusion peptide and its binding to TLR2

• Tα1–TP5 (305 μg/kg) alleviated immunosuppression induced by hydrocortisone (HC).
• Tα1–TP5 (305 μg/kg) combined with cyclophosphamide (CY) had a better tumor growth inhibitory effect than CY alone.
• Tα1–TP5 could bind to toll-like receptor 2 (TLR2), and Tα1–TP5 had a higher affinity to TLR2 than that of Tα1.

In the present study, the immunomodulatory and synergistic anti-tumor activity of thymosin α1–thymopentin fusion peptide (Tα1–TP5) was investigated in vivo. In addition, the potential receptor of Tα1–TP5 was investigated by surface plasmon resonance (SPR) binding studies. It was found that Tα1–TP5 (305 μg/kg) alleviated immunosuppression induced by hydrocortisone (HC). Tα1–TP5 (305 μg/kg) combined with cyclophosphamide (CY) had a better tumor growth inhibitory effect than CY alone. Furthermore, Tα1–TP5 had a higher affinity (KD = 6.84 μmol/L) to toll-like receptor 2 (TLR2) than Tα1 (KD = 35.4 μmol/L), but its affinity was not significantly different from that of TP5. The results of our present work indicate that Tα1–TP5 can possibly be developed as a new immunomodulatory agent.