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.
Mature red blood cells (RBCs) lack internal organelles and canonical defense mechanisms, making them both a fascinating host cell, in general, and an intriguing choice for the deadly malaria parasite ...Plasmodium falciparum (Pf), in particular. Pf, while growing inside its natural host, the human RBC, secretes multipurpose extracellular vesicles (EVs), yet their influence on this essential host cell remains unknown. Here we demonstrate that Pf parasites, cultured in fresh human donor blood, secrete within such EVs assembled and functional 20S proteasome complexes (EV-20S). The EV-20S proteasomes modulate the mechanical properties of naïve human RBCs by remodeling their cytoskeletal network. Furthermore, we identify four degradation targets of the secreted 20S proteasome, the phosphorylated cytoskeletal proteins β-adducin, ankyrin-1, dematin and Epb4.1. Overall, our findings reveal a previously unknown 20S proteasome secretion mechanism employed by the human malaria parasite, which primes RBCs for parasite invasion by altering membrane stiffness, to facilitate malaria parasite growth.
Extracellular vesicles (EVs) are produced by across almost all the living kingdoms and play a crucial role in cell-cell communication processes. EVs are especially important for pathogens, as
...parasite, the leading causing species in human malaria. Malaria parasites are able to modulate the host immune response from a distance
delivering diverse cargo components inside the EVs, such as proteins and nucleic acids. We have previously shown that imaging flow cytometry (IFC) can be effectively used to monitor the uptake of different cargo components of malaria derived EVs by host human monocytes. Here, we take this approach one step further and demonstrate that we can directly investigate the dynamics of the cargo distribution pattern over time by monitoring its distribution within two different recipient cells of the immune system, monocytes vs macrophages. By staining the RNA cargo of the vesicles and monitor the signal we were able to evaluate the kinetics of its delivery and measure different parameters of the cargo's distribution post internalization. Interestingly, we found that while the level of the EV uptake is similar, the pattern of the signal for RNA cargo distribution is significantly different between these two recipient immune cells. Our results demonstrate that this method can be applied to study the distribution dynamics of the vesicle cargo post uptake to different types of cells. This can benefit significantly to our understanding of the fate of cargo components post vesicle internalization in the complex interface between pathogen-derived vesicles and their host recipient cells.
Abstract
Parasites are responsible for the most neglected tropical diseases, affecting over a billion people worldwide (WHO, 2015) and accounting for billions of cases a year and responsible for ...several millions of deaths. Research on extracellular vesicles (EVs) has increased in recent years and demonstrated that EVs shed by pathogenic parasites interact with host cells playing an important role in the parasite's survival, such as facilitation of infection, immunomodulation, parasite adaptation to the host environment and the transfer of drug resistance factors. Thus, EVs released by parasites mediate parasite‐parasite and parasite‐host intercellular communication. In addition, they are being explored as biomarkers of asymptomatic infections and disease prognosis after drug treatment. However, most current protocols used for the isolation, size determination, quantification and characterization of molecular cargo of EVs lack greater rigor, standardization, and adequate quality controls to certify the enrichment or purity of the ensuing bioproducts. We are now initiating major guidelines based on the evolution of collective knowledge in recent years. The main points covered in this position paper are methods for the isolation and molecular characterization of EVs obtained from parasite‐infected cell cultures, experimental animals, and patients. The guideline also includes a discussion of suggested protocols and functional assays in host cells
Glycoconjugates on extracellular vesicles (EVs) play a vital role in internalization and mediate interaction as well as regulation of the host immune system by viruses, bacteria, and parasites. ...During their intraerythrocytic life‐cycle stages, malaria parasites, Plasmodium falciparum (Pf) mediate the secretion of EVs by infected red blood cells (RBCs) that carry a diverse range of parasitic and host‐derived molecules. These molecules facilitate parasite‐parasite and parasite‐host interactions to ensure parasite survival.
To date, the number of identified Pf genes associated with glycan synthesis and the repertoire of expressed glycoconjugates is relatively low. Moreover, the role of Pf glycans in pathogenesis is mostly unclear and poorly understood. As a result, the expression of glycoconjugates on Pf‐derived EVs or their involvement in the parasite life‐cycle has yet to be reported.
Herein, we show that EVs secreted by Pf‐infected RBCs carry significantly higher sialylated complex N‐glycans than EVs derived from healthy RBCs. Furthermore, we reveal that EV uptake by host monocytes depends on N‐glycoproteins and demonstrate that terminal sialic acid on the N‐glycans is essential for uptake by human monocytes. Our results provide the first evidence that Pf exploits host sialylated N‐glycans to mediate EV uptake by the human immune system cells.
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.
There is a current licensed bacterial-derived extracellular vesicle (EV)-based vaccine against meningococcal disease.As shown in animal models, parasite-derived EVs may provide promising vaccine ...agents that induce immunity against parasitic infections.Challenges associated with using parasitic EVs should be further studied before adaptation to a clinical context.
Parasitic diseases continue to afflict millions of people globally. However, traditional vaccine development strategies are often difficult to apply to parasites, leaving an immense unmet need for new effective vaccines for the prevention and control of parasitic infections. As parasites commonly use extracellular vesicles (EVs) to interact with, interfere with, or modulate the host immune response from a distance, parasite-derived EVs may provide promising vaccine agents that induce immunity against parasitic infections. We here present achievements to date and the challenges and limitations associated with using parasitic EVs in a clinical context. Despite the many difficulties that need to be overcome, we believe this direction could offer a new and reliable source of therapeutics for various neglected parasitic diseases.
Parasitic diseases continue to afflict millions of people globally. However, traditional vaccine development strategies are often difficult to apply to parasites, leaving an immense unmet need for new effective vaccines for the prevention and control of parasitic infections. As parasites commonly use extracellular vesicles (EVs) to interact with, interfere with, or modulate the host immune response from a distance, parasite-derived EVs may provide promising vaccine agents that induce immunity against parasitic infections. We here present achievements to date and the challenges and limitations associated with using parasitic EVs in a clinical context. Despite the many difficulties that need to be overcome, we believe this direction could offer a new and reliable source of therapeutics for various neglected parasitic diseases.
Many tropical countries are currently experiencing dengue (DEN), chikungunya (CHIK) and also more recently Zika (ZIKA) epidemics (particularly in Latin America). Although the risk of transmission and ...spread of these infections in temperate regions remains a controversial issue, vector-borne diseases have been widely reported in the media and have been the focus of preventive strategies by national and international policy-makers and public health authorities. In this context, we wanted to determine the extent of risk perception in infectious diseases (ID) physicians of the current and future risk of arboviral disease introduction, autochthonous case development and epidemic scenarios in France, Western Europe.
To this aim, we developed an original standardized questionnaire survey which was disseminated by the French Infectious Diseases Society to ID physician members.
We found that ID physicians perceived the risk of introduction and outbreak development of DEN, CHIK and ZIKA in France to be low to medium-low. Generalized Linear Model(s) identified medical school training, the extent of professional experience, and awareness of the French national plan regarding arboviral infections as significant predictors for lower risk perception among respondents.
Despite the fact that arboviral diseases are increasingly being imported into France, sometimes resulting in sporadic autochtonous transmission, French ID physicians do not perceive the risk as high. Better communication and education targeting health professionals and citizens will be needed to enhance the effectiveness of the French national plan to prepare against arboviral diseases.
Background
Incremental hemodialysis follows the concept of adjusting dialysis dose according to residual kidney function. Data on incremental hemodialysis in pediatric patients is lacking.
Methods
We ...conducted a retrospective analysis of children initiating hemodialysis between January 2015 and July 2020 in a single tertiary center, comparing the characteristics and outcomes of those who commenced with incremental hemodialysis vs with conventional thrice-weekly regimen.
Results
Data on forty patients, 15 (37.5%) on incremental hemodialysis and 25 (63%) on thrice-weekly hemodialysis were analyzed. No differences in age, estimated glomerular filtration rate and metabolic parameters were noted between groups at baseline, but there were more males (73 vs 40%,
p
= 0.04), more patients with congenital anomalies of kidney and urinary tract (60 vs 20%,
p
= 0.01), higher urine output (2.5 ± 1 vs 1 ± 0.8 ml/kg/h,
p
< 0.001), lower use of antihypertensive medications (20 vs 72%,
p
= 0.002) and lower prevalence of left ventricular hypertrophy (6.7 vs 32%,
p
= 0.003) in the incremental hemodialysis group vs thrice-weekly hemodialysis. During follow up, 5 (33%) incremental hemodialysis patients were transplanted, 1 (7%) remained on incremental hemodialysis at 24 months, and 9 (60%) transitioned to thrice-weekly hemodialysis at a median (IQR) time of 8.7 (4.2, 11.8) months. At last follow up, fewer patients who initiated incremental hemodialysis had left ventricular hypertrophy (0 vs 32%,
p
= 0.016) and urine output < 100 ml/24 h (20 vs 60%,
p
= 0.02) compared to thrice-weekly hemodialysis, with no significant differences in metabolic or growth parameters.
Conclusion
Incremental hemodialysis is a viable option for initiating dialysis in selected pediatric patients, that may help improve patients’ quality of life and reduce dialysis burden without compromising clinical outcome.
Graphical abstract
Background
Improved short‐ and long‐term outcomes of kidney transplantation have been achieved over the past decades due to improved immunosuppression. This may have increased the risk for infections ...and, particularly, for the viral infections: cytomegalovirus (CMV), Epstein‐Barr virus (EBV), and polyoma BK virus (BKV).
Methods
A retrospective review of viremic CMV, EBV, and BKV infections in pediatric renal transplant recipients treated and followed by a national referral center over a 10‐year period.
Results
Sixty‐seven patients (68% males) received 68 kidney grafts (62% from living donors) during the study period; the mean follow‐up period was 5.2 ± 2.4 years. Twenty‐seven viremic episodes were documented (CMV: 13, EBV: 6, BKV: 8) in 24 patients (35.2%). The median time (interquartile range) to viremia post‐transplant was 11 (4–38) months. The viral infection rate was significantly higher in the years 2014–2015 than in previous years (61% vs. 29%, p = .017). Compared to patients who did not develop viremia, patients with viremias were younger at the time of transplantation, were more likely to receive thymoglobulin induction pre‐transplant and to develop an acute rejection. Multiple logistic regression modeling identified transplant year and recipient's age as significant risk factors for viremia. Graft outcome and eGFR at the last follow‐up was similar between patients who did and did not develop viremia.
Conclusions
Viral infections continue to be a major cause of morbidity in pediatric kidney transplant recipients. However, with close monitoring and prompt intervention, patient and renal outcomes remain favorable.
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