Endalew Yizengaw Poster 2025

 Dr Endalew Yizengaw

Bahir Dar University, Ethiopia

Neutrophil Effector Functions in Response to Different Isolates of Leishmania aethiopica

Poster Abstract

Introduction: In Ethiopia, cutaneous leishmaniasis is mainly caused by Leishmania (L.) aethiopica parasites and presents in three main clinical forms. It is still not clear if the host immune response plays a role in the development of these different presentations. Neutrophils are likely to be one of the first immune cells present at the site of the sand fly bite. This study aimed to determine the effector functions of neutrophil in response to different L. aethiopica isolates.

Methods: we set up an in vitro model of infection of neutrophils with L. aethiopica and assessed some of the main neutrophil effector functions: association with and internalisation of parasites, apoptosis and reactive oxygen species (ROS) production. We used three freshly isolated clinical isolates and one isolate that has been kept in culture for decades.

Results: Our results showed by flowcytometry that all four L. aethiopica isolates had the ability to associate with neutrophils. The three clinical isolates of L. aethiopica associated more efficiently with neutrophils than the long-term cultured L. aethiopica. At 18 h, two distinct populations of neutrophils were identified that associated with L. aethiopica, CD15high and CD15low neutrophils. Confocal microscopy demonstrated that all isolates can be internalised. Our results also showed that all parasites induced apoptosis in L. aethiopica associated neutrophils. Moreover, our results showed that after 2 h, L. aethiopica-associated neutrophils upregulated their production of ROS, but to a greater extent with the long-term cultured L. aethiopica. After 18 h of incubation, CD15lowparasite+ showed an impaired ability to produce ROS compared to CD15highparasite+.

Conclusions: Using this in vitro model, our results show that different L. aethiopica parasite isolates, most notably long-term cultured parasites, had differential effects on neutrophil effector functions.

Keywords: Leishmania aethiopica, Neutrophils, ROS, Phagocytosis, Apoptosis

Biography

Dr Endalew Yizengaw is an assistant professor of immunology. Since 2015, he has been part of research projects analyzing the immune response in patients suffering from both cutaneous and visceral leishmaniases. He analysed neutrophils isolated from patients with visceral leishmaniasis for his MSc project and performed his PhD on identifying different parasite and host factors responsible for the different clinical presentations of cutaneous leishmaniasis (CL). Dr Endalew is interested in better understanding the disease pathology and role of the host immune response and characterizes the causative parasites in Ethiopia, which will help to develop a protective vaccine and/or drug.