SCREENING OF ANTIGEN CROSS-PRESENTATION POTENTIATING DRUGS FOR VACCINE DEVELOPMENT

CRESPO, MARÍA INÉS; GUANTAY, LAURA; PASCUAL, MM; HARMAN, MF; DHO, N; PISTORESSI, C; MALETTO, BELKYS; SORIA, GASTÓN; MORÓN, GABRIEL

Workshop; 1st Workshop on Drug Discovery - SAIB PABMB 2019; 2019

SAIB PABMB

The cellular immune response mediated by the induction of cytotoxic CD8+T lymphocytes (CTLs) iscrucial for therapeutic interventions in tumor immunotherapyand for the induction of protectiveimmunity against intracellular pathogens. Dendritic cells (DCs) are the only antigen (Ag) presenting cellsof the immune system with the ability to activate naïveCD8+T cells to generate CTLs, and areparticularly fitted to internalize and present exogenous Ag (from infected, tumor, or dead cells) boundto MHC I molecules to naïve CD8+T cells. This process, known as cross-presentation, is essential forantimicrobial and antitumor immunity. Non-living vaccine Ag, especially in subunit vaccines, are often poorlyimmunogenic and adjuvants are required to boost immunity. Adjuvants enhance immunogenicity of vaccinesand experimental Ag by a variety of mechanisms. One of the current major challenges is developing adjuvantsthat help generation of protective CTLs responses to soluble proteins. So far, many adjuvants activate DCs andother Ag presenting cells to provide proper co-stimulatory signals to T cells. We have found that someadjuvant compounds can also activate Ag cross-presentation, increasing T cells activation levels. Thecomplexity of Ag cross-presentation pathways challenges the identification of therapeutic targets in DCs tostimulate Ag cross-presentation. In this work we performed an in vitroscreening using 1760 drugs approved byinternational agencies such as the FDA to identify chemical entities and molecular pathways capable ofenhancing Ag cross-presentation in DCs. To achieve this goal, we developed a high-performance screeningmethod by adapting the colorimetric B3Z presentation assay using JAWSII DC cell line and OVA assoluble Ag model. B3Z is a CD8+T cell hybridoma specific for OVA257?264epitope in the context of H-2Kb(MHC I) which is activated by the detection of OVA257-264peptide associated to MHC I on the DC surface. Theprimary screening revealed an increase in Ag cross-presentation with approximately 1% of the assayeddrugs. Among the active drugs, most of the hits had antiallergic, antimalarial, antiemetic or antipsychoticeffects. Although these hits are currently under validation, it is interesting to highlight that several activecompounds have biological activities that are compatible with a potential modulatory capacity of Ag cross-presentation (i.e., we found a chloroquine derivative and it has been previously reported thatchloroquine favors soluble Ag cross-presentation, presumably by the delay of endosomal maturation). Inconclusion, we established a sensitive, fast and robust screening platform for the search of compoundscapable of stimulating Ag cross-presentation in DCs. The hits that pass the dose-response, structuraland functional validation will be evaluated as adjuvants for both preventive and therapeutic vaccinationstrategies that require a CTL response.