Biology subjects

Kropf, P.

Publications and source records attributed to Kropf, P..

6 recordsLinked to original sources

bioRxiv2025

Different isolates of Leishmania aethiopica elicit distinct effector functions in primary human monocytes

In Ethiopia, cutaneous leishmaniasis (CL) is caused by Leishmania (L.) aethiopica and presents as a spectrum of clinical forms ranging from self-healing to persistent, disfiguring lesions. Monocytes are some of the first cells to encounter Leishmania parasites in the host. Despite this, their role in L. aethiopica infection has not been investigated. In this study, primary human monocytes were co-incubated with different L. aethiopica isolates - three isolates recently collected from CL patients and one long-term cultured isolate - and their main effector functions were evaluated. After 2 hours of co-incubation, over 30% of monocytes associated with all four L. aethiopica isolates, with significantly higher association with recently isolated L. aethiopica than with the long-term cultured parasites. Phagocytosis of L. aethiopica parasites by monocytes was confirmed by confocal microscopy. Co-incubation of monocytes with all L. aethiopica isolates resulted in upregulation of reactive oxygen species in monocytes. Following incubation of monocytes with all L. aethiopica, five chemokines - monocyte chemoattractant protein (MCP)-1, MCP-4, macrophage inflammatory protein (MIP)-1, MIP-1{beta}, and interleukin (IL-8) - and four cytokines - tumour necrosis factor (TNF)-, IL-1{beta}, IL-6, and IL-10 - were detected. Our results show that the interaction of monocytes with the long-term cultured L. aethiopica differ as compared to those recently collected from CL patients. Furthermore, we define an in vitro model for the investigation of monocyte effector functions that may be useful to elucidate the role that parasites and their interactions with monocytes play in the different presentations of lesions caused by L. aethiopica.

immunology↗

bioRxiv2024

Distinct neutrophil effector functions in response to different isolates of Leishmania aethiopica

BackgroundIn 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. Since neutrophils are likely to be one of the first immune cells present at the site of the sand fly bite, we set up an in vitro model of infection of neutrophils with L. aethiopica and assessed neutrophil effector functions. We used freshly isolated clinical isolates and one isolate that has been kept in culture for decades. ResultsOur results showed by flow cytometry that up to a quarter of neutrophils were associated with L. aethiopica; and confocal microscopy demonstrated that all isolates can be internalised. The clinical isolates of L. aethiopica associated more efficiently with neutrophils than the long-term cultured L. aethiopica. At 18hrs, two distinct populations of neutrophils were identified that associated with L. aethiopica, CD15high and CD15low neutrophils. Our results also showed that all parasites induced apoptosis in L. aethiopica-associated neutrophils. Moreover, our results showed that after 2 hrs, L. aethiopica-associated neutrophils upregulated their production of ROS, but to a greater extent with the long-term cultured L. aethiopica. After 18 hrs of incubation, CD15lowparasite+ showed an impaired ability to produce ROS as compared to CD15highparasite+. ConclusionUsing this in vitro model, our results show that different L. aethiopica parasite isolates, most notably long-term cultured parasites, impacted differently on neutrophil effector functions.

immunology↗

bioRxiv2024

Parasite genetic variation and systemic immune responses are not associated with different clinical presentations of cutaneous leishmaniasis caused by Leishmania aethiopica

Cutaneous leishmaniasis (CL) is a neglected tropical skin disease, caused by the protozoan parasite Leishmania (L.). It is endemic to 90 countries and causes >200,000 new infections each year. In Ethiopia, CL is mainly caused by L. aethiopica and can present in different clinical forms: localised cutaneous leishmaniasis (LCL); mucocutaneous leishmaniasis (MCL), where the mucosa of the nose and/or the mouth are affected; and diffuse CL (DCL), characterised by non-ulcerating nodules. Persistent forms of LCL, as well as MCL and DCL, require treatment but are difficult to treat successfully and can lead to permanent disfigurement, social stigmatisation, and a mental health burden. The mechanisms behind the development of these different presentations of CL are not clearly understood, and both parasite and host factors could be involved. Here we analysed the whole genome sequence data for 48 clinical parasite isolates and show that parasites from CL cases with different presentations in a single Ethiopian setting are from the same genetic population. Furthermore, we did not identify any individual genetic variants significantly associated with disease presentation. We also measured plasma chemokine and cytokine levels of 129 CL patients presenting with different forms of CL. None of the cytokine or chemokine levels measured were significantly different between the different clinical presentations of CL. We also compared those with healthy nonendemic controls: our results show a chemokine but not a cytokine immune signature in patients with CL as compared to healthy nonendemic controls.

genomics↗

bioRxiv2024

Altered co-stimulatory and inhibitory receptors on monocyte subsets in patients with visceral leishmaniasis

Visceral leishmaniasis (VL) is a neglected tropical disease caused by parasites from the Leishmania (L.) donovani complex. VL is characterised by uncontrolled parasite replication in spleen, liver and bone marrow, and by an impaired immune response and high systemic levels of inflammation. Monocytes have been poorly characterised in VL patients. The aim of this study was to evaluate the expression levels of markers involved in the regulation of T cell responses on different subsets of monocytes from the blood of VL patients and healthy non-endemic controls (HNEC). Monocytes can broadly be divided into three subsets: classical, intermediate and non-classical monocytes. Our results show that the percentages of all three subsets stay similar at the time of VL diagnosis (ToD) and at the end of anti-leishmanial treatment (EoT). We first looked at co-stimulatory receptors: the expression levels of CD40 were significantly increased on classical and intermediate, but not non-classical monocytes, at ToD as compared to EoT and HNEC. CD80 expression levels were also increased on intermediate monocytes at ToD as compared to EoT and HNEC, and on classical monocytes only as compared to HNEC. The levels of CD86 were similar at EoT and ToD and in HNEC on classical and intermediate monocytes, but significantly higher at EoT on non-classical monocytes. We also looked at an inhibitory molecule, PD-L1. Our results show that the expression levels of PD-L1 is significantly higher on all three monocyte subsets at ToD as compared to HNEC, and to EoT on classical and intermediate monocytes. These results show that monocytes from the blood of VL patients upregulate both co-stimulatory and inhibitory receptors and that their expression levels are restored at EoT.

immunology↗

bioRxiv2021

Impaired in vitro Interferon-γ production in patients with visceral leishmaniasis is improved by inhibition of PD1/PDL-1 ligation

Visceral leishmaniasis (VL) is a neglected tropical disease that causes substantial morbidity and mortality and is a growing health problem in Ethiopia, where this study took place. Most individuals infected with Leishmania donovani parasites will stay asymptomatic, but some develop VL that, if left untreated, is almost always fatal. This stage of the disease is associated with a profound immunosuppression, characterised by impaired production of Interferon{gamma} (IFN{gamma}), a cytokine that plays a key role in the control of Leishmania parasites, and high expression levels of an inhibitory receptor, programmed cell death 1 (PD1) on CD4+ T cells. Here, we tested the contribution of the interaction between the immune checkpoint PD1 and its ligand PDL-1 on the impaired production of IFN{gamma} in VL patients. Our results show that in the blood of VL patients, not only CD4+, but also CD8+ T cells express high levels of PD1 at the time of VL diagnosis. Next, we identified PDL-1 expression on different monocyte subsets and neutrophils and show that PDL-1 levels were significantly increased in VL patients. PD1/PDL-1 inhibition resulted in significantly increased production of IFN{gamma}, suggesting that therapy using immune checkpoint inhibitors might improve disease control in these patients.

immunology↗

bioRxiv2021

Immunological factors, but not clinical features, predict visceral leishmaniasis relapse in patients co-infected with HIV

Visceral leishmaniasis (VL) has emerged as a clinically important opportunistic infection in HIV patients, as VL/HIV co-infected patients suffer from frequent VL relapse. Here, we followed cohorts of VL patients with or without HIV co-infections in Ethiopia and collected detailed clinical and immunological data during 12 months of follow-up. By the end of the study 78.1% of VL/HIV patients, but none of the VL only patients, had relapsed. Despite clinically defined cure, VL/HIV patients maintained high parasite loads, low BMI, hepatosplenomegaly and pancytopenia throughout follow-up. During detailed immunological study throughout the follow-up period, we identified three markers associated with VL relapse: i) failure to restore antigen-specific production of IFN{gamma}, ii) persistently low CD4+ T cell counts, and iii) high expression of PD1 on CD4+ T cells. We show that these three markers combine well in predicting VL relapse, and that all three measurements are needed for optimal predictive power. These three immunological markers can be measured in primary hospital settings in Ethiopia and can predict VL relapse after anti-leishmanial therapy. The use of our prediction model has the potential to improve disease management and patient care.

immunology↗