Sessions

The global significance of antimicrobial resistance and its increasing urgency demand fundamental changes in both conceptual and methodological approaches within human and veterinary medicine. In this regard, one of the most critical aspects is not only the reduction of antibiotic use, but also their replacement with novel agents, among which antimicrobial peptides (AMPs) represent promising candidates. As natural components of the innate immune system, these peptides not only exert direct antimicrobial effects but also display significant immunomodulatory activity. Owing to this latter property and their beneficial impacts on the intestinal tract, they are considered especially suitable for intensive livestock production, including poultry. However, the detailed cellular mechanisms underlying these effects remain to be more comprehensively elucidated.

To investigate these effects, our experiment aimed to examine the immunomodulatory activity of the AMP cecropin A in chicken‐derived ileal explant cultures. In our study, the peptide was applied at various concentrations (3.125 and 6.25 µg/mL), both alone and in inflammatory conditions induced by polyinosinic‐polycytidylic acid (Poly I:C, 50 µg/mL). The effect of cecropin A on cell viability was monitored by measuring metabolic activity and extracellular lactate dehydrogenase (LDH) activity using colorimetric assays. Moreover, to assess the peptide’s effect on immune response, the concentrations of inflammatory mediators interleukin (IL) 2, IL 6, interferon (IFN) γ, and "regulated on activation, normal T cell expressed and secreted" (RANTES) were determined using Luminex xMAP technology.

According to our results, cecropin A treatment did not affect cell viability in any of the experimental setups. Regarding immunomodulation, application of the peptide at 6.25 µg/mL significantly increased IL 2 production both in the absence and presence of induced inflammation. Furthermore, cecropin A at 3.125 µg/mL significantly decreased IL 6 concentration under Poly I:C-induced inflammatory conditions.

Our findings concerning cell viability suggest that cecropin A may be safely applied to the poultry intestinal tract. Additionally, our data indicate that the peptide exerts a beneficial immunomodulatory activity supporting gut homeostasis. While further studies are required to elucidate the effects of cecropin A on the poultry digestive tract in detail, our research may contribute to a deeper understanding of the immunoregulatory properties of AMPs and thereby support their future applications.