Investigations into the interaction between Leishmania australiensis and dendritic cells

Leishmaniasis is a neglected infectious disease that is continuously increasing and debilitating millions of people each year. Treatment is toxic and generally inefficient and, currently, there is no vaccine for leishmaniasis prevention. In Australia, previously thought to be free of endemic leishmaniasis, a novel species of Leishmania has been discovered infecting macropods, namely, Leishmania australiensis. Although, L. australiensis is thought to be non-pathogenic to humans due to the absence of locally acquired human leishmaniasis, this new species poses a threat to several animals. Most studies in the past looked at the interaction of Leishmania species and macrophages. However, along with macrophages, dendritic cells are targeted by Leishmania parasites, which live within the phagolysosomes. More importantly, dendritic cells are responsible for priming T helper cells, which are the main effector cells in leishmaniasis. This study showed the early events involved in leishmaniasis caused by L. australiensis focusing on the interaction of the parasite and dendritic cells. The cytokine production by L. australiensis-infected bone marrow-derived dendritic cells (BM-dendritic cells) was minimal or zero. In addition, L. australiensis appears to modulate the surface expression of MHC-II and CD86 molecules in BM-dendritic cells. Ex-vivo experiments showed that L. australiensis were unable to infect Langerhans cells compared to human-pathogenic Leishmania species. Finally, although the results were not conclusive and require repeats, the interesting observations resulted from this study might help to discover what leads to the clinical cure or the perpetuation of the disease.