Design of multi-epitope peptides containing HLA class-I and class-II-restricted epitopes derived from immunogenic Leishmania proteins, and evaluation of CD4+and CD8+T cell responses induced in cured cutaneous leishmaniasis subjects

2020

Article référencé dans le Web of Science WOS:000528655400007

Hamrouni S., Bras Goncalves Rachel, Kidar A., Aoun K., Chamakh-Ayari R., Petitdidier Elodie, Messaoudi Y., Pagniez Julie, Lemesre Jean-Loup, Meddeb-Garnaoui A.

PLoS Neglected Tropical Diseases, 2020, 14 (3), e0008093 [31 p.] ISSN 1935-2735

Author summary The control of leishmaniasis, a neglected tropical disease of public health importance, caused by protozoan parasites of the genus Leishmania, mainly relies on chemotherapy, which is highly toxic. Currently, there is no vaccine against human leishmaniasis. Peptide-based vaccines consisting of T cell epitopes identified within proteins of interest by epitope predictive algorithms are a promising strategy for vaccine development. Here, we identified multi-epitope peptides composed of HLA-I and -II-restricted epitopes, using immunoinformatic tools, within Leishmania proteins previously described as potential vaccine candidates. We showed that multi-epitope peptides used as pools were able to activate IFN-gamma producing CD4+ as well as CD8+ T cells, both required for parasite elimination. In addition, granzyme B-producing CD4+ T cells, bifunctional CD4+ IFN-gamma+/TNF-alpha+ and/or TNF-alpha+/IL-2+ T cells as well as CD4+ and CD8+ central memory T cells, all involved in Leishmania infection control, were significantly increased in response to multi-epitope peptide stimulation. As far as we know, no study has described the detection of both CD4+ and CD8+ T cell populations in response to stimulation by both HLA-I and II-restricted peptides in humans. The immunogenic HLA-I and -II-restricted multi-epitope peptides identified in this study could constitute potential vaccine candidates against human leishmaniasis. Human leishmaniasis is a public health problem worldwide for which the development of a vaccine remains a challenge. T cell-mediated immune responses are crucial for protection. Peptide vaccines based on the identification of immunodominant T cell epitopes able to induce T cell specific immune responses constitute a promising strategy. Here, we report the identification of human leukocyte antigen class-I (HLA-I) and -II (HLA-II)-restricted multi-epitope peptides from Leishmania proteins that we have previously described as vaccine candidates. Promastigote Surface Antigen (PSA), LmlRAB (L. major large RAB GTPase) and Histone (H2B) were screened, in silico, for T cell epitopes. 6 HLA-I and 5 HLA-II-restricted multi-epitope peptides, able to bind to the most frequent HLA molecules, were designed and used as pools to stimulate PBMCs from individuals with healed cutaneous leishmaniasis. IFN-gamma, IL-10, TNF-alpha and granzyme B (GrB) production was evaluated by ELISA/CBA. The frequency of IFN-gamma-producing T cells was quantified by ELISpot. T cells secreting cytokines and memory T cells were analyzed by flow cytometry. 16 of 25 peptide pools containing HLA-I, HLA-II or HLA-I and -II peptides were able to induce specific and significant IFN-gamma levels. No IL-10 was detected. 6 peptide pools were selected among those inducing the highest IFN-gamma levels for further characterization. 3/6 pools were able to induce a significant increase of the percentages of CD4+IFN-gamma+, CD8+IFN-gamma+ and CD4+GrB+ T cells. The same pools also induced a significant increase of the percentages of bifunctional IFN-gamma+/TNF-alpha+CD4+ and/or central memory T cells. We identified highly promiscuous HLA-I and -II restricted epitope combinations from H2B, PSA and LmlRAB proteins that stimulate both CD4+ and CD8+ T cell responses in recovered individuals. These multi-epitope peptides could be used as potential components of a polytope vaccine for human leishmaniasis.

Santé : généralités [050] ; Entomologie médicale / Parasitologie / Virologie [052]

Fonds IRD [F B010079053]

fdi:010079053