Antimicrobial peptide Temporin-Ra was isolated from the skin secretions of marsh frog Rana ridibunda. Temporin-Ra was chemically synthesized and purified using RP-HPLC technique. The cytotoxicity of peptide on lung airway epithelial cell line (A549) and peripheral blood mononuclear cells (PBMC) was studied by MTT assay.Furthermore, the effect of Temporin-Ra on the expression of pro-inflammatory factors such as IL-1b and IL-8 in A549 cell line was evaluated at peptide concentrations of 15, 30 and 50 lg/mL for 6, 12 and 24 h using semi-quantitative RT-PCR and real-time PCR methods. The result of our experiments revealed that Temporin-Ra decreased cell viability about 3–13 % in A549 cells and 4–6 % in PBMC cells. Moreover, Temporin-Ra induced the mRNA expression of IL-1b and IL-8 genes in a dose- and time-dependent manner. According to our results, maximum IL-8 mRNA expression was observed after a 24-h treatment of cancer cells with 50 lg/mL peptide with approximately 18-fold increase in expression. The least expression level of IL-1b was observed after 6-h of incubation in the presence of 15 lg/mL peptide with 2.5-fold increase in expression whereas the most expression level was obtained following 24 h-treatment with 50 lg/mL peptide with 26-fold increase in mRNA expression. Eventually, the present study highlights the role of Temporin-Ra as a potent antimicrobial peptide in the activation and maintenance of nflammatory processes.

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