Augmented plasma microparticles during acute Plasmodium vivax infection

Abstract

BackgroundIn the last few years, the study of microparticles (MPs) - submicron vesicles released from cells upon activation or apoptosis - has gained growing interest in the field of inflammation and in infectious diseases. Their role in the human malaria parasite Plasmodium vivax remains unexplored. Because acute vivax malaria has been related to pro-inflammatory responses, the main hypothesis investigated in this study was that Plasmodium vivax infection is associated with elevated levels of circulating MPs, which may play a role during acute disease in non-immune patients.MethodsPlasma MPs were analysed among thirty-seven uncomplicated P. vivax infections from an area of unstable malaria transmission in the Brazilian Amazon. The MP phenotype was analysed by flow cytometry using the classical MP marker, annexin, and fluorochrome-labeled monoclonal antibodies against specific cell surface markers. The frequencies of plasma MPs in P. vivax patients (n = 37) were further compared to malaria-unexposed controls (n = 15) and ovarian carcinoma patients (n = 12), a known MPs-inducing disease non-related to malaria.ResultsThe frequencies of plasma circulating MPs were markedly increased in P. vivax patients, as compared to healthy age-matched malaria-unexposed controls. Although platelets, erythrocytes and leukocytes were the main cellular sources of MPs during vivax malaria, platelet derived-MPs (PMPs) increased in a linear fashion with the presence of fever at the time of blood collection (β = 0.06, p < 0.0001) and length of acute symptoms (β = 0.36, p < 0.0001). Finally, the results suggest that plasma levels of PMPs diminish as patient experience more episodes of clinical malaria (β = 0.07, p < 0.003).ConclusionsAbundant circulating MPs are present during acute P. vivax infection, and platelet derived-MPs may play a role on the acute inflammatory symptoms of malaria vivax.

Plasmodium vivax: restricted tropism and rapid remodeling of CD71-positive reticulocytes

“…In this context, the recent demonstration that extracellular vesicles generated by P falciparum IRBCs have a role in the cellular communication 49,50 is of interest, as are the observations of circulating microparticles in clinical isolates from malaria patients. 51,52 By 6 to 8 hours postinvasion, the clathrin pits and microvesicles are no longer present on the surface of the IRBC and are replaced by caveolae of parasitic origin. These caveolae, first described in the 1970s in P vivax IRBCs, are usually associated with numerous vesicles, and the combined structure are referred to as the CVCs.…”

Biomarkers for susceptibility to infection and disease severity in human malaria

“…Recently, cell-specific microparticles, which indicate cellular damage, were demonstrated to be biological markers for cerebral dysfunction in human CM (Pankoui Mfonkeu et al 2010). Interestingly, elevated plasma concentrations of microparticles were also found in individuals with noncomplicated P. vivax infection in a study conducted in the Brazilian Amazon (Campos et al 2010), suggesting that platelet-derived microparticles may play a role in the onset of acute inflammatory symptoms of vivax malaria. These results also suggest that the microparticles are a potential biomarker for severity of malaria caused by P. falciparum or P. vivax.…”

Microvesicles and exosomes as vehicles between protozoan and host cell communication

“…Microparticles Increased levels of MVs from platelets were linked with fever and duration of symptoms [30] Plasmodium yoelii Exosomes Exosomes derived from infected reticulocytes protect mice from lethal infection [31] or RNA) has initiated a new age in the host cell-parasite relationships. What is the participation of these vesicles to the establishment of infection?…”