# Quantitative proteomics of infected macrophages reveals novel Leishmania virulence factors

## TL;DR

This study uses proteomics to identify new Leishmania proteins involved in evading host defenses during infection, offering insights into disease mechanisms and potential drug targets.

## Contribution

The study provides a high-resolution proteomic dataset of Leishmania species during macrophage infection, revealing novel virulence factors and their temporal expression patterns.

## Key findings

- Distinct temporal proteomic profiles were identified for three Leishmania species during macrophage infection.
- New virulence factors were highlighted, and their deletion reduced infectivity and stage differentiation in L. mexicana.
- The dataset serves as a resource for understanding Leishmania-host interactions and disease manifestations.

## Abstract

Leishmaniasis is a major public health problem, causing diseases ranging from self-healing skin lesions to life-threatening chronic infections. Understanding how Leishmania parasites evade the host defense system is crucial for understanding the different manifestations of the disease and for improving diagnostic tools and drug development. We performed high-resolution proteome profiling of Leishmania spp. across three species during macrophage infection and identified distinct temporal expression patterns. Clustering analysis revealed unique protein expression profiles for each Leishmania species, whereas pairwise enrichment analysis revealed specific up- and downregulation patterns at different infection stages. Our results confirmed known virulence factors and highlighted new ones, demonstrating how our dataset could be used. We validated the dataset by showing that deletion of putative L. mexicana virulence factors resulted in reduced stage differentiation capacity and infectivity.

Leishmaniasis is a devastating neglected tropical disease caused by the obligate intracellular protozoan Leishmania, with an estimated 700.000 to 1 million new cases annually worldwide. There are three main manifestations of leishmaniases: the most common cutaneous form, the mucocutaneous form and the most severe visceral form, which is almost always fatal without treatment. Despite decades of fruitful research, many important questions remain unanswered. For example, how can different Leishmania species cause different manifestations of the disease? In fact, Leishmania infantum can cause both, visceral leishmaniasis, which is relatively common, and cutaneous leishmaniasis. Furthermore, Leishmania parasites have developed a sophisticated life cycle, including an intracellular stage in phagocytic cells of their vertebrate hosts, such as macrophages. However, how parasites evade the host immune response to survive and proliferate in this hostile environment is still elusive. Quantitative mass spectrometry is a powerful tool for analyzing how parasite proteomes need to change to adapt to challenges of the host defense system to establish a chronic infection. We therefore conducted this proteomics study with three different Leishmania species during macrophage infection to generate a resource platform that provides additional data to ongoing studies in the community or serves as starting points for new projects.