PLA-PEG-encapsulated Chlamydia muridarum MOMP triggers strong innate immune responses alone and when adjuvanted with the mucosal dmLT in macrophages 2256388

Abstract Introduction Chlamydia trachomatis can lead to serious female reproductive tract complications, yet there is no FDA-approved vaccine against this pathogen. Here, we developed a nanovaccine (named PPrM) by encapsulating a Chlamydia muridarum (Cm) major outer membrane protein (MOMP) in biodegradable poly-lactic acid-polyethylene glycol (PLA-PEG) nanoparticles. We aimed to evaluate the effects of PPrM alone or combined with the double mutant labile toxin (dmLT) mucosal adjuvant, on the expression levels of Th1 cytokines, pathogen recognition receptors, and costimulatory molecules in mouse J774 Macrophages. We hypothesized that the dmLT adjuvant would potentiate the PPrM-induced innate immune responses that are critical for an efficacious chlamydial vaccine candidate. Methods We conducted dose- and time-dependent studies in which macrophages were stimulated with various concentrations of PPrM, MOMP, and dmLT, alone or combined, for 6, 24, 48, and 72 hours. The cell-free supernatants were used for cytokine-specific ELISAs, and the cell pellets were either stained for protein expression using Flow cytometry (FC), or the extraction of RNA for gene expression analysis using TaqMan qPCR. Results We observed that PPrM alone or combined with dmLT triggered enhanced production of MOMP-specific IL-6, IL-12p40, and TNF-α in a dose- and time-dependent fashion compared to MOMP alone or when adjuvanted. Our results also showed an enhanced upregulation of TLR-2, CD40, CD86, and CD80 expression levels with qPCR and confirmed with FC. Conclusion Overall, our data demonstrated the potentiating effects of the PPrM alone or when combined with dmLT on the MOMP-induced innate immune responses that are crucial in promoting a Chlamydial Th1 adaptive protective immunity in mice. Thus, the dmLT could be a promising mucosal adjuvant to consider in the development of chlamydial vaccines or nanovaccines. Funding Source This research was supported by the National Science Foundation (NSF) HBCU-UP (HRD-1911660) and the National Science Foundation (NSF)-EiR (2200529) grants and the Ph.D. Program in Microbiology at Alabama State University. Topic Categories Vaccines and Immunotherapy (VAC)