MALDI MS imaging investigation of the host response to visceral leishmaniasis.

Mass spectrometry imaging (MSI) of animal tissues has become an important tool for in situ molecular analyses and biomarker studies in several clinical areas, but there are few applications in parasitological studies. Leishmaniasis is a neglected tropical disease, and experimental mouse models have been essential to evaluate pathological and immunological processes and to develop diagnostic methods. Herein we have employed MALDI MSI to examine peptides and low molecular weight proteins (2 to 20 kDa) differentially expressed in the liver during visceral leishmaniasis in mice models. We analyzed liver sections of Balb/c mice infected with Leishmania infantum using the SCiLS Lab software for statistical analysis, which facilitated data interpretation and thus highlighted several key proteins and/or peptides. We proposed a decision tree classification for visceral leishmaniasis with distinct phases of the disease, which are named here as healthy, acute infection and chronic infection. Among others, the ion of m/z 4963 was the most important to identify acute infection and was tentatively identified as Thymosin ß4. This peptide was previously established as a recovery factor in the human liver and might participate in the response of mice to Leishmania infection. This preliminary investigation shows the potential of MALDI MSI to complement classical compound selective imaging techniques and to explore new features not yet recognized by these approaches.

Trypanocidal activity of 2-propen-1-amine derivatives on trypomastigotes culture and in animal model.

The cis and trans isomers (either E or Z isomers) of the unsubstituted and bromo-2-propen-1-amine derivatives were evaluated in vitro on Trypanosoma cruzi. The results showed that cis is the most active isomeric form against trypomastigote forms of T. cruzi, indicating that it may contribute most to the trypanocidal effect. All mice which received 5 mg kg(-1) daily for 9 consecutive days, or 200 mg kg(-1) in a single dose of the bromo derivative of 2-propen-1-amine, survived after an infection with 10(4) trypomastigotes/ml of the Y-strain of T. cruzi. They also had a significantly lower parasitemia than the controls. However, with 100 mg kg(-1) of benznidazol for 9 consecutive days, 25% of the animals died by the end of the evaluation 40 days after infection. The involvement of the biosynthesis of ergosterol in the trypanocidal effect of the unsubstituted 2-propen-1-amine derivative was investigated on proliferative epimastigote forms of the parasite. The chromatographic analyses of the lipid extracts obtained from parasites treated with 2-propen-1-amine derivatives and controls (not treated) revealed that growth inhibition is correlated with the accumulation of squalene and the decrease of ergosterol levels. These results suggest that inhibition of the biosynthesis of ergosterol is an important target for the action of the 2-propen-1-amine derivative on T. cruzi through the inhibition of the enzyme squalene epoxidase.