Extracellular vesicles released by anaerobic protozoan parasites: Current situation

Abstract

Extracellular vesicles (EVs) have emerged as a ubiquitous mechanism for transferring information between cells and organisms across all three kingdoms of life. Parasitic unicellular eukaryotes use EVs as vehicles for intercellular communication and host manipulation. Pathogenic protozoans are able to modulate the immune system of the host and establish infection by transferring a wide range of molecules contained in different types of EVs. In addition to effects on the host, EVs are able to transfer virulence factors, drug-resistance genes and differentiation factors between parasites. In this review we cover the current knowledge on EVs from anaerobic or microaerophilic extracellular protozoan parasites, including Trichomonas vaginalis, Tritrichomonas foetus, Giardia intestinalis and Entamoeba histolytica, with a focus on their potential role in the process of infection. The role of EVs in host: parasite communication adds a new level of complexity to our understanding of parasite biology, and may be a key to understand the complexity behind their mechanism of pathogenesis.

Characterization of Extracellular Vesicles Secreted by a Clinical Isolate of Naegleria fowleri and Identification of Immunogenic Components within Their Protein Cargo

“…Besides this immunomodulatory activity, EVs could serve as carriers for virulence factors [ 10 ]. The study of EVs from parasites includes helminths such as Fasciola hepatica , [ 11 ], Heligmosomoides polygyrus [ 12 ], Schistosoma mansoni [ 13 ] and Echinostoma caproni [ 14 ], as well as protozoa such as Toxoplasma gondii [ 15 ], Trypanosoma cruzi [ 16 , 17 , 18 , 19 , 20 ], Leishmania [ 21 ], different Plasmodium species [ 22 , 23 ] and anaerobic protozoan parasites such as Entamoeba histolytica , Trichomonas vaginalis and Giardia intestinalis [ 24 ], among others. More recently, and in the case of free-living amoebae with pathogenic potential, the secretion of EVs has been described in Acanthamoeba , a genus related to the production of fatal granulomatous amoebic encephalitis, keratitis and skin lesions.…”

Exosomes secreted by Blastocystis subtypes affect the expression of proinflammatory and anti-inflammatory cytokines (TNFα, IL-6, IL-10, IL-4)

“…Based on the in vitro experiments, Blastocystis parasites can elicit cytokine production and immune responses ( 38 ). Despite the availability of some Blastocystis subtype's genomes, our knowledge is still in its infancy on the biological and pathological mechanisms of the parasite ( 39 ). Curiously, membrane proteins and the integrity of the epithelial barrier could be substantially disrupted by the Blastocystis ST7 via degradation of tight proteins ( 3 ).…”

Organ-on-a-Chip for Studying Gut-Brain Interaction Mediated by Extracellular Vesicles in the Gut Microenvironment

“…It has been observed that EVs from pathogenic free-living amoeba, Acanthamoeba castellanii, destabilize epithelial and BBB cells and induce necrotic or apoptotic cell death [60]. In addition, EVs from protozoans can modulate host immunity, gut microbiome, and gut physiology [61,62], which may affect the brain indirectly. In addition to bacteria and protozoans, the human gut can harbor many other microorganisms, such as fungi, whose EVs can also interact with host cells and participate in pathogenesis [37][38][39].…”