UNVEILING THE ROLE OF LIPID METABOLISM IN ENHANCING ANTIGEN CROSS-PRESENTATION BY PERHEXILINE MALEATE STIMULATED DENDRITIC CELLS

FIAMA BOUCHARD; LUZ MARÍA PALACIOS; NICOLAS DANIEL DHO; CINTIA ARAUJO FURLAN; FEDERICO DANIEL RUIZ MORENO; BELKYS A. MALETTO; GABRIEL MORÓN; MARÍA INÉS CRESPO

San Luis

Congreso; LXXI Reunión de la Sociedad Argentina de Inmunología; 2023

Sociedad Argentina de Inmunología

The immune response mediated by cytotoxic CD8+ T cells (CTLs) plays a pivotalrole in both tumor immunotherapy and defense against intracellular pathogens.Dendritic cells (DCs) have the ability to internalize and present exogenousantigens (Ag) via MHC I to activate naïve CD8+ T cells, a process termed crosspresentation.Adjuvants are necessary to robust CTL response, especially insubunit vaccines. However, due to the intricate nature of Ag cross-presentationpathways, identifying therapeutic targets that can serve as adjuvants forgenerating protective CTL responses has proven challenging. To address this,we previously performed a high throughput screening of drug libraries approvedby international agencies. The aim was to identify novel compounds andmolecular pathways capable of enhancing Ag cross-presentation in DCs. Ourapproach involved the adaptation of the B3Z presentation assay using theJAWSII DC cell line and Ovalbumin (OVA) as the soluble Ag. In this study, weelucidate the mechanisms underlying the enhancement of cross- presentationby Perhexiline Maleate (PM), one of the five active compounds identified.Notably, PM does not influence OVA internalization nor MHC I-surfaceexpression in JAWSII DCs. Moreover, incubating JAWSII DCs with PM led toincreased translocation of Ags from endosomes to the cytosol (p<0.001), anessential step in cross-presentation. To assess the capability of PM-stimulatedDCs to activate naïve CD8 T cells, we co-cultured Flt3-L BMDCs pre-treatedwith PM + OVA with CD8+ T cells purified from OT-I mice. After three days, ourobservations indicated that PM-stimulated DCs activate naïve CD8+ T cells,triggering proliferation (p<0.05), CD44 expression (p<0.05), and IFNγsecretion.PM is known to inhibit the mitochondrial enzyme carnitine palmitoyltransferase1 (CPT1), thereby reducing fatty acid metabolism. In alignment with this, ourprior work demonstrated that PM augmented the presence of lipid bodies percell, which has previously been related to the ability of DC to cross-present Agsby various researchers. Consequently, we evaluated the involvement of lipidmetabolism in the cross-presentation process. Firstly, we found that Etomoxir,another CPT1 inhibitor, enhance OVA cross-presentation by JAWSII DCs(p<0.01), implicating CPT1 as a potential target. Secondly, we discovered thatboth TOFA, an inhibitor of Acetyl-CoA Carboxylase-α (ACCA), andXanthohumol, an inhibitor of diacylglycerol acyltransferase 1 (DGAT-1) andDGAT-2, counteracted the increase in OVA cross-presentation observed in PMstimulatedJAWSII DCs (p<0.05 and p<0.01 respectively), without affectingother active compounds.Further studies will be engaged to completely understand the role of lipidmetabolism in the enhancing cross-presentation ability in PM-stimulated DCs.