TDK conference 2019

Bacterial antibiotic resistance is an emerging issue in the field of human and veterinary medicine as well. One of the major causes is the irresponsible and excessive use of antibiotics in animal farming. As it is a great risk for humanity there is a huge effort for developing new molecules capable to take over, either partially or entirely, the role of the current antibiotics.

Antimicrobial peptides (AMPs) are a promising natural compound family. As members of the innate immunity they are very effective against microbes and the same time they can moderate the inflammation caused by the bacterial infection.

We used primary hepatocyte- and non-parenchymal cell monocultures and their co-cultures of chicken origin for testing the effect of the antimicrobial peptide chicken heterophil peptide-1 (CHP-1). Lipopolysaccharide (LPS) was used to induce inflammation on the cell culture models, applied in 0, 1, 10 and 50 µg/ml. The CHP-1 was added in 0, 0.5, and 5 µg/ml concentrations to the cell culture medium. The cells were incubated with the supplemented medium for 8 hours. The metabolic activity of the cells was measured by CCK-8 test. The anti-inflammatory effect of the applied AMP was investigated by the determination of the concentration of IL-6 and by investigating the oxidative stress level using Amplex Red method.

In the case of mono-cultures the metabolic activity of the cells was not effected significantly by the 0.5 µg/ml CHP-1 treatment; however, it was significantly increased by the 5 µg/ml CHP-1 treatment when applied together with all LPS concentrations. None of the CHP-1 treatments had a significant effect on the metabolic activity of the cells of co-culture models.

The measurements showed a significantly decreased H2O2 production after the 0.5 µg/ml CHP-1 treatment either in monoculture and co-culture models, meanwhile it was significantly elevated after the use of 5 µg/ml CHP-1 treatment, together with most LPS concentrations.

There was no significant change in the IL-6 concentration after the application of the 0.5 µg/ml CHP-1 treatment in the culture medium of hepatocyte monocultures; however, after administering it in 5 µg/ml concentration the production of IL-6 was significantly elevated independently from LPS exposure. In the hepatocyte - non-parenchymal cell co-cultures we could observe significantly decreased IL-6 concentration triggered by 0.5 µg/ml CHP-1 in case of most LPS concentrations, altough IL-6 concentration was significantly elevated after the 5 µg/ml CHP-1 treatment in the 0 µg/ml LPS and 1 µg/ml LPS groups.

We can conclude that the investigated AMP, CHP-1 in a lower concentration, such as the applied 0.5 µg/ml, can have a great influence on the oxidative stress level and on the inflammatory response; however, it may have an unfavourable effect on the cells in the higher concentration of 5 µg/ml.