Sequencing of L. infantum-infected female- and male-derived primary human macrophages
Women generally mount stronger immune responses than men, offering better protection against infectious diseases, including leishmaniasis - a vector-borne parasitic disease. Depending on the infecting Leishmania species, the disease causes various clinical forms. Leishmania infantum (L. infantum) belongs to the L. donovani complex and causes visceral leishmaniasis (VL) around the Mediterranean Basin, the Middle East and, increasingly, South and Central America, where immunocompromised patients and infants are mainly affected by the disease. Additionally, L. infantum is known for its clinical pleomorphism, as it can cause both VL and cutaneous leishmaniasis in endemic regions.Across all manifestations, leishmaniasis tends to impact men more severely, as shown by epidemiological studies and reproduced in experimental models of the disease. In our study, we analyzed the effects of L. infantum infection on isolated human monocyte-derived macrophages (hMdMs) from men and women, as macrophages act as the main mammalian host cell. Through high-throughput screening, we found that hMdMs from male donors showed higher infection rates and parasite loads than those from female donors, even in in vitro monocultures. To find determinants for this dichotomy on transcriptional level, we performed RNA sequencing of infected macrophages from female and male donors at different time points post infection (6, 16 and 52 hours post infection) to add to the understanding of the biological reasons for the increased resilience in to leishmaniasis in females, which could be crucial for developing individualized treatment regimens.HMdMs were generated from BuffyCoat samples from healthy donors and mature macrophages were infected with L. infantum stationary promastigotes at a multiplicity of infection (MOI) of 15:1. Macrophages were incubated with parasites for 4 h followed by three washing steps to remove the extracellular parasites. Subsequently, macrophages were incubated for the required time period. Incubation for the required time frame with phagocytic beads of comparable size to parasites and at the same MOI were used as phagocytosis control and to account for parasite-specific changes in gene expression.