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

Congreso; LXXI REUNIÓN SAI; 2023

The immune response mediated by cytotoxic CD8+ T cells (CTLs) plays a pivotal role in both tumor immunotherapy and defense against intracellular pathogens. Dendritic cells (DCs) have the ability to internalize and present exogenous antigens (Ag) via MHC I to activate naïve CD8+ T cells, a process termed cross-presentation. Adjuvants are necessary to robust CTL response, especially in subunit vaccines. However, due to the intricate nature of Ag cross-presentation pathways, identifying therapeutic targets that can serve as adjuvants for generating protective CTL responses has proven challenging. To address this, we previously performed a high throughput screening of drug libraries approved by international agencies. The aim was to identify novel compounds and molecular pathways capable of enhancing Ag cross-presentation in DCs. Our approach involved the adaptation of the B3Z presentation assay using the JAWSII DC cell line and Ovalbumin (OVA) as the soluble Ag. In this study, we elucidate the mechanisms underlying the enhancement of cross-presentation by Perhexiline Maleate (PM), one of the five active compounds identified. Notably, PM does not influence OVA internalization nor MHC I-surface expression in JAWSII DCs. Moreover, incubating JAWSII DCs with PM led to increased translocation of Ags from endosomes to the cytosol (p<0.001), an essential step in cross-presentation. To assess the capability of PM-stimulated DCs to activate naïve CD8 T cells, we co-cultured Flt3-L BMDCs pre-treated with PM + OVA with CD8+ T cells purified from OT-I mice. After three days, our observations indicated that PM-stimulated DCs activate naïve CD8+ T cells, triggering proliferation (p<0.05), CD44 expression (p<0.05), and IFN-γ secretion.PM is known to inhibit the mitochondrial enzyme carnitine palmitoyltransferase 1 (CPT1), thereby reducing fatty acid metabolism. In alignment with this, our prior work demonstrated that PM augmented the presence of lipid bodies per cell, which has previously been related to the ability of DC to cross-present Ags by various researchers. Consequently, we evaluated the involvement of lipid metabolism 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 that both TOFA, an inhibitor of Acetyl-CoA Carboxylase-α (ACCA), and Xanthohumol, an inhibitor of diacylglycerol acyltransferase 1 (DGAT-1) and DGAT-2, counteracted the increase in OVA cross-presentation observed in PM-stimulated JAWSII DCs (p<0.05 and p<0.01 respectively), without affecting other active compounds.Further studies will be engaged to completely understand the role of lipid metabolism in the enhancing cross-presentation ability in PM-stimulated DCs.