Bacteriocin BacSp222 and Its Succinylated Forms Exhibit Proinflammatory Activities Toward Innate Immune Cells

Justyna Śmiałek; Monika Bzowska; Alicja Hinz; Renata Mężyk-Kopeć; Kamilla Sołtys; Paweł Mak

doi:10.2147/JIR.S362066

Bacteriocin BacSp222 and Its Succinylated Forms Exhibit Proinflammatory Activities Toward Innate Immune Cells

J Inflamm Res. 2022 Aug 12:15:4601-4621. doi: 10.2147/JIR.S362066. eCollection 2022.

Authors

Justyna Śmiałek^#¹, Monika Bzowska^#², Alicja Hinz², Renata Mężyk-Kopeć², Kamilla Sołtys², Paweł Mak¹

Affiliations

¹ Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
² Department of Cell Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.

^# Contributed equally.

Abstract

Purpose: The zoonotic opportunistic pathogen Staphylococcus pseudintermedius 222 produces BacSp222 - an atypical peptide exhibiting the features of a bacteriocin, a virulence factor, and a molecule modulating the host inflammatory reaction. The peptide is secreted in an unmodified form and, additionally, two forms modified posttranslationally by succinylation. This study is a comprehensive report focusing on the proinflammatory properties of such molecules.

Methods: The study was performed on mouse monocyte/macrophage-like and endothelial cell lines as well as human neutrophils. The following peptides were studied: BacSp222, its succinylated forms, the form deprived of formylated methionine, and a reference bacteriocin - nisin. The measurements of the nitric oxide (NO) level, induced NO synthase (iNOS) expression, the profile of secreted cytokines, NF-kappa-B activation, reactive oxygen species (ROS) biosynthesis, and the formation of extracellular traps were conducted to evaluate the proinflammatory activity of the studied peptides.

Results: BacSp222 and its succinylated forms effectively induced NO production and iNOS expression when combined with IFN-gamma in macrophage-like cells. All natural BacSp222 forms used alone or with IFN-gamma stimulated the production of TNF-alpha, MCP-1, and IL-1-alpha, while the co-stimulation with IFN-gamma increased IL-10 and IL-27. Upregulated TNF-alpha secretion observed after BacSp222 exposition resulted from increased expression but not from membrane TNF-alpha proteolysis. In neutrophils, all forms of bacteriocin upregulated IL-8, but did not induce ROS production or NETs formation. In all experiments, the activities of deformylated bacteriocin were lower or unequivocal in comparison to other forms of the peptide.

Conclusion: All naturally secreted forms of BacSp222 exhibit proinflammatory activity against monocyte-macrophage cells and neutrophils, confirming that the biological role of BacSp222 goes beyond bactericidal and cytotoxic effects. The atypical posttranslational modification (succinylation) does not diminish its immunomodulatory activity in contrast to the lower antibacterial potential or cytotoxicity of such modified form established in previous studies.

Keywords: NF-kappa-B activation; Staphylococcus pseudintermedius 222; cytokines; neutrophils; nisin; nitric oxide; posttranslational modifications.