AK2 Antibacterial Synthetic Peptide Can Potentiate Macrophage Responses

Document Type : Original Article


1 Immunoregulation Research Center, Shahed University, Tehran, Iran.

2 Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.


Background: Emphasis on substitutional medications with the elevated bacterial resistance to current antibiotics is pivotal. We evaluated the antibacterial effect of AK2 by Minimum Bactericidal Concentration (MBC) and Minimum inhibitory Concentration (MIC) and its impact on macrophage responses in 17 strains of pathogenic bacteria. The gene expression of macrophage’s cytokines was evaluated. Accordingly, the bioinformatic assessment predicted this peptide’s physicochemical characteristics, behavior, and structures. The present study aimed to assess the antibacterial effect of AK2 peptides on Macrophage responses.
Materials and Methods: Cytotoxicity level was assessed by MTT assay on the HeLa cell line. The hemolytic activity of peptides on red blood cells was evaluated. The Griess assay was performed to assess the amount of macrophage nitric oxide production. The real-time PCR method measured the iNOS, IFN-γ, and TNF-α gene expression in isolated macrophages. 
Results: Peptide concentrations (13-60 µg/mL) were observed as the MBC and MIC value results for various bacteria. No remarkable cytotoxicity was observed at 30 and 60 µg/ml concentrations after 24h. iNOS, IFN-γ, and TNF-α gene expression were upregulated. There was also a higher secretion of nitric oxide in 48 hour-culture of the cell line with peptide. Great antibacterial activity was observed in some bacterial strains, particularly B. melitensis. 
Conclusion: AK2 peptides display suitable antibacterial activity with negligible toxicity for host cells. This peptide could also stimulate macrophage responses through nitric oxide production and gene expression in proinflammatory cytokines. 


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