Sex specific differences in Leishmania infection and treatment of human primary macrophages

Abstract

Leishmaniasis is a group of neglected tropical diseases with around 1,4 million new cases each year. Depending on Leishmania species, different clinical manifestations of the disease can be observed, with symptoms varying from cutaneous lesions (“cutaneous Leishmaniasis) to visceral organ damage (“visceral Leishmaniasis”) with high lethality when left untreated. With the current rise in temperature induced by anthropogenic climate change and a globalized world as we see it today, in the future it is not unlikely that Leishmania parasites also migrate to northern western world countries. Increasing resistance of parasites to current treatment methods generates the need for new drugs or new therapy strategies. Given that the development of disease is highly dependent on the characteristics of host immune response, combining leishmanicidal drugs with immune response modifiers is an intriguing option for combination treatments in the future to lower the doses of toxic drugs and to ameliorate adverse effects and i ncrease treatment efficacy by circumventing drug resistance mechanisms. The research groups of groups of Prof. Meier (University of Hamburg) and Prof. Lotter (BNITM) have developed six chemically synthesized analoga of a glycosylphosphatidylinositol anchor derived from lipopeptidephosphoglycan found in the membrane of Entamoeba histolytica, called Eh-1 - Eh-6 which show immune modulatory functions and protection during Leishmania infection making them interesting drug candidates for combination therapy of Leishmaniasis. A male bias of infection and disease severity can be observed in Leishmaniasis and other parasitic diseases indicating a background of sex specific immunity. During this work different strategies for the treatment of human monocyte-derived macrophages infected with Leishmania (L.) major and L. infantum have been tested in in vitro models of cutaneous and visceral Leishmaniasis (Figure 0-1). Mono and combination therapy strategies with Amphotericin B, Miltefosine, Imiquimod and drug candidate Eh-1 were tested using high content drug screening assays identifying Miltefosine or Amphotericin B with Imiquimod as combinations with cooperative potential. Eh-1 did not provide convincing evidence for combination therapy. Still, in cytokine analyses of L. major infection, Eh-1 showed expression of protective cytokines indicating increased inflammasome mediated oxidative clearance of parasites, which was amplified in combination with Amphotericin B to provide cooperative protection. In L. infantum infection Eh-1 also showed protection, but independent of protective cytokine production. During infection experiments several instances of sex specific immunity were observed, as females showed higher degree of inflammatory cytokine production, stronger pro inflammatory phenotype and lower overall infection with L. infantum. In this context Estradiol was identified as mediator of protection against L. infantum infection and Dihydrotestosterone mediated higher susceptibility to infection for female human monocyte-derived macrophages.