On 2015 July 18-19 and 20 -23 were held in Vancouver, Canada, the “IAS 2015 Towards an HIV Cure Symposium” and the “8th International AIDS Society Conference on HIV pathogenesis, treatment and Prevention”.
iHIVARNA consortium presented a study entitled “Monocyte-derived DC Electroporated with mRNAs Encoding both specific HIV Antigens and DC Adjuvants are able to improve T cell Functionality” in both meetings. The objective of the study was to test in vitro a combination of mRNA sequences that fulfil two main objectives. On the one hand, a specific T cell activation immunogen mRNA that focuses the response onto the most vulnerable targets in the HIV viral proteome and on the other hand, a previously tested stimulus (TriMix: a mixture of CD70+CD40L+caTLR4 mRNAs) for appropriate activation of antigen presenting cells (DCs). DCs were generated from peripheral blood monocytes (MDDC) from chronically HIV infected patients by incubation with GM-CSF and IL-4. These cells were electroporated with TriMix (15 μg) and/or HIVACAT (20 μg) mRNA, with their respective controls. After that, DCs were cocultured with autologous PBMCs for up to 6 days. In addition, the maturation profile of MDDCs (CD80, CD83, CD86, CCR7) was analyzed by FACS 24h after electroporation. Functional analysis was performed using different techniques: 25-multiplex Luminex assay, T cell proliferation by CFSE and IFN-γ ELISPOT at different time points. Increased expression of CD80, CD83 and CCR7 was observed on MDDCs upon electroporation with TriMix mRNA. Functionally, mRNA electroporated MDDCs were able to stimulate T cells from HIV-infected individuals on cART in vitro. In fact, MDDCs electroporated with both HIV antigens and TriMix, induced higher T-cell activation than their respective separated components or whole AT2-inactivated virus in terms of both IFNγ secretion and proliferation. Other Th1, Th2 and proinflammatory cytokines showed a similar profile secretion pattern. Finally, a higher proportion of stimulated CD8+ T cells, than of CD4+ T cells, was detected.
In conclusion, mRNA electroporation of MDDCs improved their maturation status and was able to enhance HIV specific T cells responses. Our results suggest that this mRNA combination could be considered for a HIV therapeutic vaccination approach.