Authors: S. Dixit, M. Taha, S.R. Singh, V.A. Dennis
Affilation: Alabama State University, United States
Pages: 335 - 338
Keywords: chlamydia trachomatis, bacteria, major outer membrane protein, poly (lactic acid)-b-poly (ethylene glycol), antibody
In pursuit of a vaccine against Chlamydia trachomatis, the most reported bacterial sexually transmitted infection, we previously reported that encapsulation of M278, a peptide derived from the major outer protein of C. trachomatis within PLA-PEG nanoparticles triggered enhanced systemic adaptive immune responses in mice. Because PLA-PEG can facilitate uptake of antigens by antigen presenting cells (APCs) or by increasing the influx of APCs in to the injection site, here in this study, we investigated the potential of encapsulated-M278 to stimulate production of Th1 cytokines by mouse and human APCs. Our results revealed that mouse J774 macrophages and human THP-1 monocytes exposed in vitro to different concentrations of PLA-PEG-PBS (PBS encapsulated PLA-PEG) and PLA-PEG-M278 (encapsulated-M278) induced marked production of IL-6 and IL-12 Th1 cytokines, suggesting the ability of encapsulated-M278 to directly activate APCs. We next immunized four groups of BALB/c mice subcutaneously with PLA-PEG-PBS, PLA-PEG-M278, M278 or PBS and two weeks after the last immunization vaginal wash samples were collected for mucosal antibody analyses. PLA-PEG-M278 immunized mice produced higher IgG and IgG2b M278-specific antibodies as compared to bare M78 immunized mice, suggesting that PLA-PEG potentiated the capacity of M278 to induce mucosal antibody responses in mice. Studies are ongoing to determine the mechanisms involved in uptake of nanoparticles by APCs and for enhancement of immune responses in mice.