Unravelling the biochemical aspects of the interaction between ticks and <i>Leishmania</i> using a tick cell line

Leishmaniasis comprises a group of vector-borne neglected tropical diseases caused by species of the obligatory intracellular parasite Leishmania, transmitted by the bite of dipteran sand flies. Infected dogs serve as the primary domestic reservoir of Leishmania parasites and are often found in close association with various arthropods, such as fleas and ticks. There have been recent reports of Leishmania infections occurring in areas non-endemic for sand fly species, leading to reconsideration of the hypothesis that other arthropods, such as ticks, may also play a significant role in the natural history and epidemiology of leishmaniasis. Here, we used a tick cell line as a tool to study Leishmania infantum and tick interaction. The results showed that L. infantum can bind to and proliferate inside Ixodes scapularis IDE8 tick cells. The infection did reduce tick cell viability and induce reactive oxygen species (ROS) production. Lipid profile analysis showed that the presence of L. infantum increased oxysterol in tick cells and influenced tick cell lipid biosynthesis, since an increase in glycerolipids and esterified cholesterol was observed in infected cells at 48 h. Further experiments are necessary to elucidate whether Leishmania can overcome the various biochemical and tissue barriers within ticks and be transmitted to the host.