Functional Characterization of Porcine NK-Lysin: A Novel Immunomodulator That Regulates Intestinal Inflammatory Response

• Published in: Molecules (Basel, Switzerland) Switzerland), 2021-07, Vol.26 (14), p.4242
• Main Authors: Lin, Qian, Fu, Qingqing, Chen, Daiwen, Yu, Bing, Luo, Yuheng, Huang, Zhiqing, Zheng, Ping, Mao, Xiangbing, Yu, Jie, Luo, Junqiu, Yan, Hui, He, Jun
• Format: Article
• Language: English
• Subjects: Amino acids; Anti-inflammatory agents; Antibacterial activity; Antibiotics; Antimicrobial activity; Antimicrobial agents; antimicrobial peptide; Antimicrobial peptides; Apoptosis; Bacteria; Bacterial infections; Cell viability; Cloning; Diarrhea; E coli; Enzymes; Gel electrophoresis; Gram-positive bacteria; hemolytic activity; Immune system; Immunomodulation; Immunomodulators; Infections; Inflammation; Inflammatory response; Interleukin 6; Intestine; Localization; Lysine; MIC; Microorganisms; Natural killer cells; NF-κB protein; Pathogens; Peptides; Porcine NK-Lysin; Proteins; Small intestine; Tumor necrosis factor-α; Zonula occludens-1 protein
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules26144242

Porcine NK-Lysine (PNKL) is a new antimicrobial peptide (AMP) identified in the small intestine. In this study, PNKL protein was obtained through heterologous expression in Escherichia coli and was estimated by SDS-PAGE at 33 kDa. The antibacterial activities of PNKL were determined using various bacterial strains and showed broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria. Furthermore, E. coli K88-challenged IPEC-J2 cells were used to determine PNKL influences on inflammatory responses. Hemolytic assays showed that PNKL had no detrimental impact on cell viability. Interestingly, PNKL elevated the viability of IPEC-J2 cells exposure to E. coli K88. PNKL significantly decreased the cell apoptosis rate, and improved the distribution and abundance of tight junction protein ZO-1 in IPEC-J2 cells upon E. coli K88-challenge. Importantly, PNKL not only down regulated the expressions of inflammatory cytokines such as the IL-6 and TNF-α, but also down regulated the expressions of NF-κB, Caspase3, and Caspase9 in the E. coli K88-challenged cells. These results suggest a novel function of natural killer (NK)-lysin, and the anti-bacterial and anti-inflammatory properties of PNKL may allow it a potential substitute for conventionally used antibiotics or drugs.