title: Leishmania major infection in humanized mice induces systemic infection and provokes a nonprotective human immune response.
abstract: BACKGROUND
  Leishmania (L.) species are the causative agent of leishmaniasis. Due to the lack of efficient vaccine candidates, drug therapies are the only option to deal with cutaneous leishmaniasis. Unfortunately, chemotherapeutic interventions show high toxicity in addition to an increased risk of dissemination of drug-resistant parasites. An appropriate laboratory animal based model is still missing which allows testing of new drug strategies in the context of human immune cells in vivo.
  
  
  RESULTS
  Humanized mice were infected subcutaneously with stationary phase promastigote L. major into the footpad. The human immune response against the pathogen and the parasite host interactions were analyzed. In addition we proved the versatility of this new model to conduct drug research studies by the inclusion of orally given Miltefosine. We show that inflammatory human macrophages get infected with Leishmania parasites at the site of infection. Furthermore, a Leishmania-specific human-derived T cell response is initiated. However, the human immune system is not able to prevent systemic infection. Thus, we treated the mice with Miltefosine to reduce the parasitic load. Notably, this chemotherapy resulted in a reduction of the parasite load in distinct organs. Comparable to some Miltefosine treated patients, humanized mice developed severe side effects, which are not detectable in the classical murine model of experimental leishmaniasis.
  
  
  CONCLUSIONS
  This study describes for the first time L. major infection in humanized mice, characterizes the disease development, the induction of human adaptive and innate immune response including cytokine production and the efficiency of Miltefosine treatment in these animals. In summary, humanized mice might be beneficial for future preclinical chemotherapeutic studies in systemic (visceral) leishmaniasis allowing the investigation of human immune response, side effects of the drug due to cytokine production of activated humane immune cells and the efficiency of the treatment to eliminate also not replicating ("hiding") parasites.
authors: Institute of Immunology, University of Regensburg, Regensburg, Bavaria, Germany.
authors: Anja Kathrin
authors: AK
authors: Wege
authors: Christian
authors: C
authors: Florian
authors: Wolfgang
authors: W
authors: Ernst
authors: Nicole
authors: N
authors: Zimara
authors: Ulrike
authors: U
authors: Schleicher
authors: Frank
authors: F
authors: Hanses
authors: Maximilian
authors: M
authors: Schmid
authors: Uwe
authors: U
authors: Ritter
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000008:administration & dosage; D004195:Disease Models, Animal; D006801:Humans; D057131:Immune Evasion; D018320:Leishmania major / Q000276:immunology* / Q000472:pathogenicity*; D016773:Leishmaniasis, Cutaneous / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology*; D051379:Mice; D016513:Mice, SCID; D010767:Phosphorylcholine / Q000008:administration & dosage / Q000031:analogs & derivatives; D016896:Treatment Outcome
chemical_list: D000981:Antiprotozoal Agents; D010767:Phosphorylcholine; C039128:miltefosine