Different activation of monocyte-derived macrophages by antimicrobial peptides at a titanium tibial implantation in rabbits

- We obtained monocyte-derived macrophages from rabbits with Ti tibial implants.
- Activity of Mf polarized by LPS or Dex was further modified by AMP extract.
- Mfs stimulated with AMP exerted both pro-and anti-inflammatory features.

The aim of our study was to assess the functional and morphological features of monocyte derived Mfs from rabbits with titanium (Ti) tibial implants, their ability to polarize towards M1 or M2 and their reactivity after stimulation with neutrophil antimicrobial peptides extract (AMP). The study was conducted on six White New Zealand rabbits with tibial implants of pure titanium Grade 2. Blood was taken before implantation and 14 days after biomaterial implantation. Then, blood-derived Mfs were cultured and their function was assessed on the basis of morphological changes, generation of nitric oxide (NO), superoxide, and proteases release after treatment with LPS or dexamethasone (Dex). As a result of polarization we specified two subpopulations of Mfs with features characteristic of each subtype. M1 stimulated with LPS exhibited an increased NO and superoxide level, and M2 stimulated with Dex which showed higher arginase and lower free radical generation. Addition of AMP evoked further changes in Mfs morphology and function. After 24 h stimulation with AMP an increase of NO was observed in all cultures, whereas after 48 h it decreased. Production of superoxide lowered, especially after 48 h, when M1 generated 6.00 ± 0.2 nM and M1/AMP culture generated 5.2 ± 0.1 nM of superoxide. Our study revealed that activated Mfs stimulated with AMP demonstrated both pro- and anti-inflammatory features. Moreover, we did not detect significant differences between the response of Mfs cultured from blood derived monocytes before and after implantation of Ti implants.