A dmLT Adjuvanted Chlamydial MOMP Nanovaccine Enhances the Induced Innate Immune Responses In vitro
Discipline: Nanoscience or Materials Science
Session: 2
Room: 5 - Embassy A
Aguy C. Nguiakam Sipowe - Alabama State University
Co-Author(s): Elizabeth B. Norton, Tulane University; Rajnish Sahu, Alabama State University; Vanella Tadjuidje, Alabama State University; Othreniel Forte, Alabama State University; Vida A. Dennis, Alabama State University
Chlamydia, the most encountered bacterial sexually transmitted infection worldwide and in the US, is caused by Chlamydia trachomatis (Ct), an obligate intracellular gram-negative bacterium affecting both men and women. Ct infections are underdiagnosed, leading to severe complications such as pelvic inflammatory diseases, ectopic pregnancy, and sterility, making it a major public health concern. Antibiotics are effective but have limited effects against reinfections and damage associated with persistent infection. However, there is still no FDA-approved vaccine against Ct. Hence, there is an urgent need to develop an effective one. In our study, we developed a nanovaccine (named PPrM) by encapsulating the major outer membrane protein (MOMP) of Chlamydia muridarum in biodegradable Poly-Lactic Acid – Polyethylene Glycol (PLA-PEG) nanoparticles. We aimed to evaluate the effects of PPrM alone and adjuvanted with the double mutant labile toxin (dmLT) adjuvant on the expression levels of Th1 cytokines (IL-6, IL-12p40, and TNF-α), pathogen recognition receptor (TLR2), and co-stimulatory molecules (CD80, CD86, and CD40) as induced by the encapsulated MOMP in vitro 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. As such, dose responses and time-kinetic studies were conducted whereby macrophages were stimulated with various concentrations of PPrM, MOMP, and dmLT, either alone or admixed, for 6, 24, 48, and 72 hours. Cell-free supernatants were collected for cytokine-specific ELISAs and RNA for gene expression using TaqMan qPCR. Our results showed that macrophages stimulated with PPrM induced an 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 admixed with dmLT. We also observed upregulation of TLR-2, CD40, and CD80 gene expression levels. Of significance, the dmLT markedly enhanced the PPrM-induced immune responses, suggesting the potentiating effects of the adjuvant. In conclusion, adjuvanting the chlamydial MOMP nanovaccine with dmLT bolstered the MOMP-induced innate immune responses in macrophages by potentiating the expression of Th1 cytokines, TLR2, and co-stimulatory molecules, essential to fostering a Th1 adaptive response for protective immunity. Overall, dmLT may be an attractive adjuvant to include in the development of chlamydial vaccines.
Funder Acknowledgement(s): This research was supported by the National Science Foundation (NSF) HBCU-UP (HRD-1911660), the National Institute of Health (NIH)-NIGMS-RISE (1R25GM106995-01) grants, and the Ph.D. Program in Microbiology at Alabama State University.
Faculty Advisor: Vida A. Dennis, vdennis@alasu.edu
Role: I did all the work: the cell culture, experiment planning, and conduct (dose-response, time Kinetic, ELISA, qPCR), as well as the graph arrangements.