ABSTRACT
The protozoan parasites Plasmodium falciparum, Leishmania spp. and Trypanosoma cruzi continue to exert a significant toll on the disease landscape of the human population in sub‐Saharan ...Africa and Latin America. Control measures have helped reduce the burden of their respective diseases—malaria, leishmaniasis and Chagas disease—in endemic regions. However, the need for new drugs, innovative vaccination strategies and molecular markers of disease severity and outcomes has emerged because of developing antimicrobial drug resistance, comparatively inadequate or absent vaccines, and a lack of trustworthy markers of morbid outcomes. Extracellular vesicles (EVs) have been widely reported to play a role in the biology and pathogenicity of P. falciparum, Leishmania spp. and T. cruzi ever since they were discovered. EVs are secreted by a yet to be fully understood mechanism in protozoans into the extracellular milieu and carry a cargo of diverse molecules that reflect the originator cell's metabolic state. Although our understanding of the biogenesis and function of EVs continues to deepen, the question of how EVs in P. falciparum, Leishmania spp. and T. cruzi can serve as targets for a translational agenda into clinical and public health interventions is yet to be fully explored. Here, as a consortium of protozoan researchers, we outline a plan for future researchers and pose three questions to direct an EV's translational agenda in P. falciparum, Leishmania spp. and T. cruzi. We opine that in the long term, executing this blueprint will help bridge the current unmet needs of these medically important protozoan diseases in sub‐Saharan Africa and Latin America.
The framework summarises the potential translational utilities of extracellular vesicles in Plasmodium falciparum, Leishmania spp. and Trypanosoma cruzi. It highlights three strategic questions to be interrogated to usher in a translational future. TR1, translational agenda 1; TR2, translational agenda 2; TR3, translational agenda 3; CD, Chagas disease.
Progress in computing capabilities has enhanced science in many ways. In recent years, various branches of machine learning have been the key facilitators in forging new paths, ranging from ...categorizing big data to instrumental control, from materials design through image analysis. Deep learning has the ability to identify abstract characteristics embedded within a data set, subsequently using that association to categorize, identify, and isolate subsets of the data. Scanning probe microscopy measures multimodal surface properties, combining morphology with electronic, mechanical, and other characteristics. In this review, we focus on a subset of deep learning algorithms, that is, convolutional neural networks, and how it is transforming the acquisition and analysis of scanning probe data.
Pathogens are thought to use host molecular cues to control when to initiate life-cycle transitions, but these signals are mostly unknown, particularly for the parasitic disease malaria caused by ...Plasmodium falciparum. The chemokine CXCL10 is present at high levels in fatal cases of cerebral malaria patients, but is reduced in patients who survive and do not have complications. Here we show a Pf 'decision-sensing-system' controlled by CXCL10 concentration. High CXCL10 expression prompts P. falciparum to initiate a survival strategy via growth acceleration. Remarkably, P. falciparum inhibits CXCL10 synthesis in monocytes by disrupting the association of host ribosomes with CXCL10 transcripts. The underlying inhibition cascade involves RNA cargo delivery into monocytes that triggers RIG-I, which leads to HUR1 binding to an AU-rich domain of the CXCL10 3'UTR. These data indicate that when the parasite can no longer keep CXCL10 at low levels, it can exploit the chemokine as a cue to shift tactics and escape.
Many human pathogens use host cell‐surface receptors to attach and invade cells. Often, the host‐pathogen interaction affinity is low, presenting opportunities to block invasion using a soluble, ...high‐affinity mimic of the host protein. The Plasmodium falciparum reticulocyte‐binding protein homolog 5 (RH5) provides an exciting candidate for mimicry: it is highly conserved and its moderate affinity binding to the human receptor basigin (KD ≥1 μM) is an essential step in erythrocyte invasion by this malaria parasite. We used deep mutational scanning of a soluble fragment of human basigin to systematically characterize point mutations that enhance basigin affinity for RH5 and then used Rosetta to design a variant within the sequence space of affinity‐enhancing mutations. The resulting seven‐mutation design exhibited 1900‐fold higher affinity (KD approximately 1 nM) for RH5 with a very slow binding off rate (0.23 h−1) and reduced the effective Plasmodium growth‐inhibitory concentration by at least 10‐fold compared to human basigin. The design provides a favorable starting point for engineering on‐rate improvements that are likely to be essential to reach therapeutically effective growth inhibition.
Extracellular vesicles in parasite survival Ofir-Birin, Yifat; Regev-Rudzki, Neta
Science (American Association for the Advancement of Science),
02/2019, Letnik:
363, Številka:
6429
Journal Article
Necroptosis is a regulated, nonapoptotic form of cell death initiated by receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL) proteins. It is considered to be a ...form of regulated necrosis, and, by lacking the "find me" and "eat me" signals that are a feature of apoptosis, necroptosis is considered to be inflammatory. One such "eat me" signal observed during apoptosis is the exposure of phosphatidylserine (PS) on the outer plasma membrane. Here, we demonstrate that necroptotic cells also expose PS after phosphorylated mixed lineage kinase-like (pMLKL) translocation to the membrane. Necroptotic cells that expose PS release extracellular vesicles containing proteins and pMLKL to their surroundings. Furthermore, inhibition of pMLKL after PS exposure can reverse the process of necroptosis and restore cell viability. Finally, externalization of PS by necroptotic cells drives recognition and phagocytosis, and this may limit the inflammatory response to this nonapoptotic form of cell death. The exposure of PS to the outer membrane and to extracellular vesicles is therefore a feature of necroptotic cell death and may serve to provide an immunologically-silent window by generating specific "find me" and "eat me" signals.
Extracellular vesicles (EVs) provide a central mechanism of cell-cell communication. While EVs are found in most organisms, their pathogenesis-promoting roles in parasites are of particular interest ...given the potential for medical insight and consequential therapeutic intervention. Yet, a key feature of EVs in human parasitic protozoa remains elusive: their mechanisms of biogenesis. Here, we survey the current knowledge on the biogenesis pathways of EVs secreted by the four main clades of human parasitic protozoa: apicomplexans, trypanosomatids, flagellates, and amoebae. In particular, we shine a light on findings pertaining to the Endosomal Sorting Complex Required for Transport (ESCRT) machinery, as in mammals it plays important roles in EV biogenesis. This review highlights the diversity in EV biogenesis in protozoa, as well as the related involvement of the ESCRT system in these unique organisms.
The role of epicardial fat (eFat)-derived extracellular vesicles (EVs) in the pathogenesis of atrial fibrillation (AF) has never been studied. We tested the hypothesis that eFat-EVs transmit ...proinflammatory, profibrotic, and proarrhythmic molecules that induce atrial myopathy and fibrillation.
We collected eFat specimens from patients with (n=32) and without AF (n=30) during elective heart surgery. eFat samples were grown as organ cultures, and the culture medium was collected every 2 days. We then isolated and purified eFat-EVs from the culture medium, and analyzed the EV number, size, morphology, specific markers, encapsulated cytokines, proteome, and microRNAs. Next, we evaluated the biological effects of unpurified and purified EVs on atrial mesenchymal stromal cells and endothelial cells in vitro. To establish a causal association between eFat-EVs and vulnerability to AF, we modeled AF in vitro using induced pluripotent stem cell-derived cardiomyocytes.
Microscopic examination revealed excessive inflammation, fibrosis, and apoptosis in fresh and cultured eFat tissues. Cultured explants from patients with AF secreted more EVs and harbored greater amounts of proinflammatory and profibrotic cytokines, and profibrotic microRNA, as well, than those without AF. The proteomic analysis confirmed the distinctive profile of purified eFat-EVs from patients with AF. In vitro, purified and unpurified eFat-EVs from patients with AF had a greater effect on proliferation and migration of human mesenchymal stromal cells and endothelial cells, compared with eFat-EVs from patients without AF. Last, whereas eFat-EVs from patients with and without AF shortened the action potential duration of induced pluripotent stem cell-derived cardiomyocytes, only eFat-EVs from patients with AF induced sustained reentry (rotor) in induced pluripotent stem cell-derived cardiomyocytes.
We show, for the first time, a distinctive proinflammatory, profibrotic, and proarrhythmic signature of eFat-EVs from patients with AF. Our findings uncover another pathway by which eFat promotes the development of atrial myopathy and fibrillation.
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