Increasing in cysteine proteinase B expression and enzymatic activity during in vitro differentiation of Leishmania (Viannia) braziliensis: First evidence of modulation during morphological transition.

Leishmania (Viannia) braziliensis presents adaptive protease-dependent mechanisms, as cysteine proteinases B (CPB). This study investigates the expression of three cpb gene isoforms and CPB enzymatic activity during the parasite differentiation. Relative expression levels of LbrM.08.0810 gene were assessed, exhibiting a higher quantity of transcripts in the logarithmic promastigotes phase than in the stationary promastigotes phase (>1.5 times). The cbp gene tends to decrease during acid pH shock and increases when the temperature rises (>1.3 times). LbrM.08.0820 and LbrM.08.0830 genes exhibited similar expression profiles to LbrM.08.0810 gene, with lower levels being observed overall. The proteolytic activity exhibits a gradual increase during the parasite's differentiation with low levels in samples of logarithmic promastigotes phase (3.2 ± 0.08 mmol min-1 mg protein-1) to a peak of activity after 72 h of incubation at 32 °C (4.2 ± 0.026 mmol min-1 mg protein-1) followed by a subsequent decrease of 68 % of peak activity levels after 96 h of incubation at 32 °C (2.8 ± 0.37 mmol min-1 mg protein-1). These activities were also measured in the presence of selective inhibitors for cysteine proteinases, such as Z-Phe-Phe-fluoromethyl ketone and trans-epoxysuccinyl-L-leucylamido(4-guanidino)butane, demonstrating their source as cathepsin-like proteinases. To the best of our knowledge, this report presents the first description of a modulation of cathepsin L-like expression during the L. (V.) braziliensis in vitro differentiation induced by acid pH and high temperature.