Summary:
The term leishmaniasis describes a group of diseases caused by protozoan parasites of the genus Leishmania, endemic to the tropic environments of Africa, America, India, and the Mediterranean and southwest Asia.
It is a group of diseases with a range of clinical manifestations ranging from autogenous skin ulcers to severe disease with massive tissue destruction. The World Health Organization has even registered it in neglected tropical diseases. The available drugs against the disease have several shortcomings. It was shown that the parasite develops resistance to the drugs and the toxicity levels rise. Also, the duration of treatment required is time consuming and therefore the need to develop a vaccine to prevent leishmaniasis is imperative. Developments in nanotechnology in recent years provide new approaches to the treatment of leishmaniasis. In particular, several studies have focused on the use of nanoparticles as antigen carriers.
Self-emulsifying drug delivery systems (SNEDDS) are an isotropic mixture of oils / lipids, surfactants, occasional co-solvents or co-emulsifiers and drugs. Their small size helps them pass effectively through different blocks of the gastrointestinal tract and thus manage to spread effectively through the mucosa. The use of SNEDDS nanoparticles has been found to help improve solubility, enhance bioavailability and reduce drug variability. Due to the above characteristics, their possible use in the development of vaccines is of particular interest.
The aim of the present master thesis was to evaluate the ability of SNEDDs to be used as antigen vectors for vaccine development against experimental visceral leishmaniasis.
Initially, a study of the potential cytotoxic activity of SNEDDS nanocarriers was performed, which showed that they were not toxic below a specific concentration for macrophages in the J774A.1 cell line. Subsequently, the in vitro uptake study of labeled nanocarriers showed that SNEDDS are uptaken by both macrophages and dendritic cells. The effect of SNEDDS nanocarriers on dendritic cells maturation was studied, sonce. Dendritic cells play an critical role in activating immune responses. The results showed that the nanocarriers did not appear to induce dendritic maturation.
After in vivo administration (intramuscular and subcutaneous) of SNEDDS nanocarriers in BALB/c mice, it was shown that SNEDDS were located in the lymphatic organs, spleen and lymph nodes. The study also showed that the intramuscular administration is more effective in uptake of nanocarriers.
Finally, the ability of 3 peptides of the Leishmania parasite to induce desired type of immune responses (cellular and humoral response) was determined. The peptides used, from parasite proteins, have been analyzed by in silico approach and appear to be recognized by mouse MHCI and MHCII molecules. They were also designed in such a way that their physicochemical characteristics (isoelectric point and hydrophobicity) are suitable for their incorporation into SNEDDS, which are hydrophobic. The results showed that only peptide 2 is capable of inducing the production of total IgG antibodies as well as lymphocyte proliferation.
In conclusion, the SNEDDS nanocarriers are capable of being used as antigen carriers in candidat vaccines against leishmaniasis. Also, a possible antigent that could be used in future studies is peptide 2.
