Isolation and immunogenicity of extracted outer membrane vesicles from Pseudomonas aeruginosa under antibiotics treatment conditions

Different types of antibiotics have been indicated to enhance the secretion of OMVs from Pseudomonas aeruginosa. We aimed to investigate the effect of meropenem and amikacin antibiotics on inducing the secretion of OMVs and immunologic features in P. aeruginosa.

The OMVs were prepared from P. aeruginosa under hypervesiculation condition (treatment with amikacin and meropenem), and extraction was carried out by the sequential ultracentrifugation. Physicochemical features of extracted OMVs were evaluated by electron microscopy and SDS-PAGE. To quantify antibody synthesis and function after immunization with OMV, we used ELISA, serum bactericidal activity, and opsonophagocytosis. Production of cytokines from splenocytes of immunized mice was measured with ELISA.

Specific-antibody IgG production, particularly IgG1 subclass, increased in mice primed with hypervesiculation-derived OMVs compared to normal condition-derived OMVs. Serum bactericidal activity and opsonophagocytosis of secreted antibody was enhanced in mice primed with hypervesiculation-derived OMVs. Investigation of cytokine production showed the upregulation of IL-8, IL-12, IL-17, and TNF-α and downregulation of IL-10.

Based on our findings, OMVs production can be increased by treating P. aeruginosa with amikacin and meropenem antibiotics. Moreover, hypervesiculation-derived OMV scan possibly activate the humoral and cellular immune response more than normal OMVs.