Role of human miRNA in the pathogenesis of Malaria
Principal Investigator: Nahla Galal Metwally 🇪🇬
Funding (Leibniz center of infection , Jürgen Manschot Stiftung)
PhD scholarship applications are welcomed (DAAD, Jürgen Manschot, etc..), for this please, drop me an email (metwally@bnitm.de).
Establishing the causal role of any single mechanism in severe malaria in humans is difficult. The pathogenesis of severe malaria is hotly debated; some suggest that cytoadhesion is the overriding pathogenic mechanism, whilst others believe that inflammatory processes are more important. An accumulating body of evidence indicates that vascular endothelial dysfunction is also important and could be the interface between cytoadhesion and inflammation.
Several cellular signaling pathways, including immune signaling pathways, need to be fine-tuned during infection, and some of these are regulated by miRNAs. miRNAs are non-coding RNAs of ~20 nucleotides in length that occur in mammals, plants and viruses. The human genome is estimated to contain 2300 true human mature miRNAs, of which 1115 are currently annotated, according to miRBase version 22
Our proposed theory
Our hypothesis is that the dysfunction of ECs is a trigger for severe malaria complications. This disrupts the balance between vasoconstriction and vasodilatation and predisposes to cytoadhesion of iRBCs, endothelial proliferation and leakage of the BBB. By regulating gene expression within ECs, certain miRNA candidates may be involved in controlling these events. These miRNAs may sense the presence of IEs through cell-cell communication between iRBCs and ECs.
Our aim
In this project, we scan the human miRNA profiles in the different cells that are involved during the major events of severe P. falciparum infection and cerebral malaria. The experiments are designed to monitor the first steps and role of parasite or host factors in triggering complications.
How human host cells react to / are affected by P. falciparum infection
1. MiRNA profiles of human red blood cells
Yifan Wu 🇨🇳
Viable cells communicate indirectly by releasing extracellular vesicles (EVs) that contain miRNAs, mRNAs, and proteins. EVs are either formed inside multivesicular bodies (exosomes) or directly from the plasma membrane (microvesicles). EVs released from RBCs contain miRNAs coupled with Argonaute 2; these complexes can alter gene expression in other types of cells upon uptake of the RBC-EVs. Currently, minimal information is available on the role of miRNAs in the pathogenesis of P. falciparum complications.
We analyzed the miRNA profiles of non-infected human RBCs (niRBCs), ring-infected RBCs (riRBCs), and trophozoite-infected RBCs (trRBCs), as well as those of EVs secreted from these cells. Hsa-miR-451a was the most abundant miRNA in all RBC and RBC-EV populations, but its expression level was not affected by P. falciparum infection. Overall, the miRNA profiles of RBCs and their EVs were altered significantly after infection. Most of the differentially expressed miRNAs were shared between RBCs and their EVs. A target prediction analysis of the miRNAs revealed the possible identity of the genes targeted by these miRNAs (CXCL10, OAS1, IL7, and CCL5) involved in immunomodulation (Wu et al., 2023).
Functional analysis of these miRNAs will follow.
2. miRNA profiles of human brain endothelial cells and thier extracellular vesicles
Pilar Tauler 🇪🇸
Endothelial cells (ECs) maintain about 60000 miles of blood vessels in human body. They are heterogenous group of cells that are responsive to signals from microenvironment. ECs line the blood and lymphatic vessels with exception of the placenta. These cells provide a physical barrier between the circulation and tissues.
EC activation is involved in the pathogenesis of severe malaria syndrome and networks of host pathways might be involved in the disease outcome. The parasite either relies on or dysregulates these pathways to survive in the human host. During P.falciparum infection, IEs are released into the blood circulation of the human host, and then the number of IEs increases exponentially until they trigger the host immune response. So far, innate immune responses triggered in response to malaria infection are described as the result of a rapture of schizonts, which leads to the release of large amounts of digestive vacuoles, hemozoin and waste products of the parasite in the circulation. Thus, the innate immune cells are stimulated and the production of proinflammatory responses is induced. Proinflammatory cytokines and chemokines activate ECs, which undergo changes resulting in “EC dysfunction”, typically characterized by decreased endothelial expression of nitric oxide (NO; a profound vasodilator), and increase the expression of cell adhesion molecules, resulting in increased binding of circulating leukocytes to these cells.
EVs derived from P. falciparum IEs are known to contain both parasite protein and miRNAs, which can be transferred to the recipient host and modulate target genes.
The role of EVs derived from human brain endothelial cells in the pathogenic cascade during severe malaria is not yet investigated.
In this project, we purify the EVs derived from primary brain endothelial cells and analysis thier miRNA profile under different stimulus.
3. miRNA profiles of human lung endothelial cells and thier extracellular vesicles
Hannifeh Torabi 🇮🇷
To dissect the distinct profiles of tissue specific-iRBCs communication, we designed this study to compare the miRNA/mRNA of primarylung ECs up on exposure to different stimuli that are present during P. falciparum infection. Aiming to deeply mine the transcriptomic data and piece together the puzzle of severe malaria.
Shear stress effect on the human endothelium
ECs are normally under different shear stresses depending on the dimension of vessels. Shear stress is defined as the dragging frictional force generated by flowing blood. ECs respond to shear stress through structural alignment of the cells and the secretion of subsets of proteins. Normal physiological flow is a laminar flow, associated with physiological phenotype of the ECs. The exposure of ECs to different shear stresses leads to various intracellular responses that modulated the expression of some receptors on the cell surface.
Authentic stimulation of the ECs is important to monitor in detail the first signal of the proinflammatory response and the following cascades. We, therefore, set out to examine the initiating signal for the activation of ECs during interaction with P. falciparum IEs (Wu and Bouws et al., 2021).
Human Blood brain barrier model under shear stress
Alumni
Doctoral Thesis
Yifan Wu 🇨🇳 (2023): The role of human endothelium and microRNAs as active participants in the immune response and pathogenesis during malaria
Diploma and Master Thesis
Maryéva Bessemoulin🇫🇷 (2023): Analysis of the activation of human brain endothelial cells during Plasmodium falciparum infection under shear stress
Hanifeh Torabi 🇮🇷 (2022): Influence of Plasmodium falciparum infected erythrocytes on the gene expression of human endothelial cells
Johannes Allweier 🇩🇪 (2021): Investigation of febrile conditions and stimulation through TNFa on human brain and lung endothelial cells under shear stress using Next-Generation-Sequencing
Shu 'Jerry' Njiyang 🇨🇲 (2020): Characterising the response of different human endothelial cells exposed to cytoadhesion of P. falciparum infected erythrocytes
Jean Maximilian Rakotonirinalalao 🇩🇪 🇲🇬 (2020): Characterization of the binding capacity of Plasmodium falciparum infected erythrocytes to different endothelial cell lines
Philip Bouws 🇩🇪 (2019): Stimuli der knob-Ausbildung Plasmodium falciparum (WELCH, 1897) infizierter Erythrozyten
Bachelor Thesis
Margherita Pignataro 🇮🇹 (2023): Analysing the binding capacity of P. falciparum infected erythrocytes expressing MAL6P1.252 gene to human brain endothelial cells.
Milad Temori 🇩🇪 🇦🇫 (2022): Anreicherung und Transkriptomanalyse von P. falciparum infizierten Erythrozyten, die an den humanen EPCR Rezeptor binden
David Danicic-Rauchberger 🇦🇹 (2021): Characterization of the cytoadhesion of 3D7 Plasmodium falciparum infected erythrocytes expressiong MAL6P1.252 var gene to human brain and lung cells
