An overview of qualitative and quantitative platelet abnormalities in schistosomiasis.

Schistosomiasis is a neglected tropical disease referring to the infection with blood parasitic trematodes of the genus Schistosoma. It impacts millions of people worldwide, primarily in low-to-middle-income countries. Patients infected with schistosomiasis often exhibit a distinct hematological profile, including anemia, eosinophilia, thrombocytopenia, and coagulopathy. Platelets, essential components of the hemostatic system, play a crucial role in the pathogenesis of schistosomiasis. Schistosomes secrete serine proteases and express ectoenzymes, such as calpain protease, alkaline phosphatase (SmAP), phosphodiesterase (SmNPP5), ATP diphosphohydrolase (SmATPDase1), serine protease Sk1, SmSP2, and Sm22.6, which can interfere with platelet normal functioning. This report provides comprehensive, up-to-date information on platelet abnormalities observed in patients with schistosomiasis, highlighting their importance in the disease progression and complications. It delves into the interactions between platelets and schistosomes, including the impact of platelet dysfunction on hemostasis and immune responses, immune-mediated platelet destruction, and the potential mechanisms by which schistosome tegumental ectoenzymes affect platelets. Furthermore, the report clarifies the relationship between platelet abnormalities and clinical manifestations such as thrombocytopenia, coagulation disorders, and the emergence of portal hypertension and gastrointestinal bleeding. Understanding the complex interplay between platelets and schistosomes is crucial for improving patient management and outcomes in schistosomiasis, particularly for those with platelet alterations. This knowledge contributes to improved diagnostic methods, innovative treatment strategies, and global efforts to control and eliminate schistosomiasis.

Clinical and economic impacts of large volume delayed sampling and pathogen reduction technology platelet processing strategies in the United States.

BACKGROUND: Large volume delayed sampling (LVDS) and pathogen reduction technology (PRT) are strategies for platelet processing to minimize transfusion of contaminated platelet components (PCs). This study holistically compares the economic and clinical impact of LVDS and PRT in the United States. STUDY DESIGN AND METHODS: A decision model was constructed to simulate collection, processing, and use of PCs and to compare processing strategies: PRT with 5-day shelf life, LVDS with 7-day shelf life (LVDS7), and LVDS with 5-day shelf life extended to 7 days with secondary testing (LVDS5/2). Target population was adults requiring two or more transfusions. Collection, processing, storage, and distribution data were obtained from the National Blood Collection and Utilization Survey and published literature. Patient outcomes associated with transfusions were obtained from AABB guidelines, meta-analyses, and other published clinical studies. Costs were obtained from reimbursement schedules and other published sources. RESULTS: Given 10,000 donated units, 9512, 9511, and 9651 units of PRT, LVDS5/2, and LVDS7 PCs were available for transfusion, respectively. With these units, 1502, 2172, and 2329 transfusions can be performed with similar levels of adverse events. Assuming 30 transfusions a day, a hospital would require 69,325, 47,940, and 45,383 units of PRT, LVDS5/2, and LVDS7 platelets to perform these transfusions. The mean costs to perform transfusions were significantly higher with PRT units. CONCLUSIONS: Compared with PRT, LVDS strategies were associated with lower costs and higher PC availability while patients experienced similar levels of adverse events. Increased utilization of LVDS has the potential to improve efficiency, expand patient access to platelets, and reduce health care costs.

Inactivation of a broad spectrum of viruses and parasites by photochemical treatment of plasma and platelets using amotosalen and ultraviolet A light.

BACKGROUND: The INTERCEPT Blood System pathogen reduction technology (PRT), which uses amotosalen and ultraviolet A light treatment (amotosalen/UV-PRT), inactivates pathogens in plasma and platelet components (PCs). This review summarizes data describing the inactivation efficacy of amotosalen/UVA-PRT for a broad spectrum of viruses and parasites. METHODS: Twenty-five enveloped viruses, six nonenveloped viruses (NEVs), and four parasites species were evaluated for sensitivity to amotosalen/UVA-PRT. Pathogens were spiked into plasma and PC at high titers. Samples were collected before and after PRT and assessed for infectivity with cell cultures or animal models. Log reduction factors (LRFs) were defined as the difference in infectious titers before and after amotosalen/UV-PRT. RESULTS: LRFs of ≥4.0 log were reported for 19 pathogens in plasma (range, ≥4.0 to ≥7.6), 28 pathogens in PC in platelet additive solution (PC-PAS; ≥4.1-≥7.8), and 14 pathogens in PC in 100% plasma (PC-100%; (≥4.3->8.4). Twenty-five enveloped viruses and two NEVs were sensitive to amotosalen/UV-PRT; LRF ranged from >2.9 to ≥7.6 in plasma, 2.4 or greater to greater than 6.9 in PC-PAS and >3.5 to >6.5 in PC-100%. Infectious titers for four parasites were reduced by >4.0 log in all PC and plasma (≥4.9 to >8.4). CONCLUSION: Amotosalen/UVA-PRT demonstrated effective infectious titer reduction for a broad spectrum of viruses and parasites. This confirms the capacity of this system to reduce the risk of viral and parasitic transfusion-transmitted infections by plasma and PCs in various geographies.

Development of a quantitative, portable, and automated fluorescent blue-ray device-based malaria diagnostic equipment with an on-disc SiO2 nanofiber filter.

There is an urgent need to develop an automated malaria diagnostic system that can easily and rapidly detect malaria parasites and determine the proportion of malaria-infected erythrocytes in the clinical blood samples. In this study, we developed a quantitative, mobile, and fully automated malaria diagnostic system equipped with an on-disc SiO2 nanofiber filter and blue-ray devices. The filter removes the leukocytes and platelets from the blood samples, which interfere with the accurate detection of malaria by the blue-ray devices. We confirmed that the filter, which can be operated automatically by centrifugal force due to the rotation of the disc, achieved a high removal rate of leukocytes (99.7%) and platelets (90.2%) in just 30 s. The automated system exhibited a higher sensitivity (100%) and specificity (92.8%) for detecting Plasmodium falciparum from the blood of 274 asymptomatic individuals in Kenya when compared to the common rapid diagnosis test (sensitivity = 98.1% and specificity = 54.8%). This indicated that this system can be a potential alternative to conventional methods used at local health facilities, which lack basic infrastructure.

In vitro effects of environmental isolates of Acanthamoeba T4 and T5 over human erythrocytes and platelets.

Free-living amoebae of the genus Acanthamoeba have been associated with keratitis and encephalitis. Some factors related to their pathogenic potential have been described, including the release of hydrolytic enzymes, and the adhesion and phagocytosis processes. However, other factors such as their effect over the hemodynamics and microcirculation elements have not been fully investigated. This work determines the in vitro activity of potentially pathogenic environmental isolates of Acanthamoeba genotype T4 and T5 over erythrocytes and platelets. The hemolytic activity (dependent and independent of contact), as well as the production of ADP of ten environmental isolates of Acanthamoeba obtained from dental units, combined emergency showers, dust, and hospital water, were measured. Tests were carried out over erythrocytes in suspension and blood agar plates, incubated at 4 °C, room temperature and 37 °C. Erythrophagocytosis and platelet aggregation assays were also performed. Live trophozoites of all of the isolates tested showed a hemolytic activity that was temperature-dependent. Over erythrocytes in suspension, variable hemolysis percentages were obtained: a maximum of 41% and a minimum of 15%. Regarding hemolysis over agar plates, two patterns of hemolysis were observed: double and simple halos. Conditioned medium and crude extracts of trophozoites did not show hemolytic activity. Erythrophagocytosis by Acanthamoeba was also observed; however, no production of ADP was determined by the employed methodology.

Impaired frequencies and function of platelets and tissue remodeling in chronic Chagas disease.

Chronic inflammation, as a consequence of the persistent infection with Trypanosoma cruzi, leads to continuous activation of the immune system in patients with chronic Chagas disease. We have previously shown that increased sera levels of soluble P-selectin are associated with the severity of the cardiomyopathy distinctive of chronic Chagas disease. In this study, we explored the expression of biomarkers of platelet and endothelial activation, tissue remodeling, and mediators of the coagulation cascade in patients at different clinical stages of chronic Chagas heart disease. The frequencies of activated platelets, measured by the expression of CD41a and CD62P were decreased in patients with chronic Chagas disease compared with those in uninfected subjects, with an inverse association with disease severity. Platelet activation in response to adenosine diphosphate was also decreased in T. cruzi-infected subjects. A major proportion of T. cruzi infected subjects showed increased serum levels of fibrinogen. Patients with severe cardiac dysfunction showed increased levels of endothelin-1 and normal values of procollagen I. In conclusion, chronic infection with T. cruzi induced hemostatic alterations, even in those patients who do not yet present cardiac symptoms.

Insight into the Effects of Plasmodium chabaudi on Platelets Using Carbon-Fiber Microelectrode Amperometry.

Platelets are anuclear circulating cell bodies within the bloodstream commonly known for their roles in clot formation during vascular injury to prevent blood loss. They also have significant impact in a range of diseases, including malaria. However, the role of platelets in malaria is controversial, with contradicting evidence suggesting either that they assist in destruction of malarial parasites or facilitate a severe form of malaria. Precedent work suggests that the timing of infection is critical in determining whether platelets switch roles from being protective to deleterious. As such, the work herein makes use of the unique mechanistic perspective offered by carbon-fiber microelectrode amperometry (CFMA) to understand how platelet secretion is impacted in malarial infection stages (ascending parasite count versus descending parasite count). Malarial platelet behavior was compared to platelets from noninfected control mice by probing their exocytotic function. Results suggest that mouse malaria caused by the parasite Plasmodium chabaudi, during both ascending and descending infection stages, reduces platelet exocytotic events and delays platelet granule fusion; in addition, platelets are more impacted by the disease early in the infection stages. In all, understanding platelet behavior in the malarial context may present new therapeutic routes to treat or cure malaria.

Diagnostic Value of Platelet and Leukocyte Counts in the Differential Diagnosis of Fever in the Returning Traveler.

Malaria, arbovirus infection and travelers' diarrhea are among the most common etiologies of fever after a stay in the tropics. Because the initial symptoms of these diseases often overlap, the differential diagnostic remains a challenge. The aim of this study was to establish the effectiveness of platelet and leukocyte counts in the differential diagnosis of fever in the returning traveler. Between 2013 and 2016, patients with a clinical suspicion of malaria, who had thick blood smears performed were retrospectively included. The microbiological etiology of each episode was established based on molecular detection in the case of arbovirus infection, the detection of pathogens in stool samples for diarrhea and other gastrointestinal symptoms and the thick and thin blood smear results for malaria. A total of 1,218 episodes were included. Malaria, arbovirus infection, and diarrhea and other gastrointestinal symptoms caused 102 (8.4%), 68 (5.6%), and 72 (5.9%) episodes, respectively. The median platelet counts in malaria episodes were 89 × 109/L and thrombocytopenia (< 150,000 × 109 platelets/L) yielded a 98% negative predictive value to predict malaria. The median leukocyte counts in arbovirus infection episodes were 3.19 × 109/L and leucopenia (< 4 × 109 leukocytes/L) yielded a 97.9% negative predictive value to predict arbovirus infections. Platelet and leukocyte counts were not significantly altered in episodes caused by diarrhea and other gastrointestinal symptoms. Initial platelet and leukocyte counts might be useful for the clinical differential diagnosis of fever in the returning traveler. Although these results are insufficient to establish a diagnosis, they should be considered in the initial clinical assessment.

Platelets kill circulating parasites of all major Plasmodium species in human malaria.

Platelets are understood to assist host innate immune responses against infection, although direct evidence of this function in any human disease, including malaria, is unknown. Here we characterized platelet-erythrocyte interactions by microscopy and flow cytometry in patients with malaria naturally infected with Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, or Plasmodium knowlesi Blood samples from 376 participants were collected from malaria-endemic areas of Papua, Indonesia, and Sabah, Malaysia. Platelets were observed binding directly with and killing intraerythrocytic parasites of each of the Plasmodium species studied, particularly mature stages, and was greatest in P vivax patients. Platelets preferentially bound to the infected more than to the uninfected erythrocytes in the bloodstream. Analysis of intraerythrocytic parasites indicated the frequent occurrence of platelet-associated parasite killing, characterized by the intraerythrocytic accumulation of platelet factor-4 and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling of parasite nuclei (PF4+TUNEL+ parasites). These PF4+TUNEL+ parasites were not associated with measures of systemic platelet activation. Importantly, patient platelet counts, infected erythrocyte-platelet complexes, and platelet-associated parasite killing correlated inversely with patient parasite loads. These relationships, taken together with the frequency of platelet-associated parasite killing observed among the different patients and Plasmodium species, suggest that platelets may control the growth of between 5% and 60% of circulating parasites. Platelet-erythrocyte complexes made up a major proportion of the total platelet pool in patients with malaria and may therefore contribute considerably to malarial thrombocytopenia. Parasite killing was demonstrated to be platelet factor-4-mediated in P knowlesi culture. Collectively, our results indicate that platelets directly contribute to innate control of Plasmodium infection in human malaria.

Human babesiosis: Indication of a molecular mimicry between thrombospondin domains from a novel Babesia microti BmP53 protein and host platelets molecules.

Human babesiosis is caused by the apicomplexan parasite Babesia microti, which is of major public health concern in the United States and elsewhere, resulting in malaise and fatigue, followed by a fever and hemolytic anemia. In this paper we focus on the characterization of a novel B. microti thrombospondin domain (TSP1)-containing protein (BmP53) from the new annotation of the B. microti genome (locus 'BmR1_04g09041'). This novel protein (BmP53) had a single TSP1 and a transmembrane domain, with a short cytoplasmic tail containing a sub-terminal glutamine residue, but no signal peptide and Von Willebrand factor type A domains (VWA), which are found in classical thrombospondin-related adhesive proteins (TRAP). Co-localization assays of BmP53 and Babesia microti secreted antigen 1 (BmSA1) suggested that BmP53 might be a non-secretory membranous protein. Molecular mimicry between the TSP1 domain from BmP53 and host platelets molecules was indicated through different measures of sequence homology, phylogenetic analysis, 3D structure and shared epitopes. Indeed, hamster isolated platelets cross-reacted with mouse anti-BmP53-TSP1. Molecular mimicry are used to help parasites to escape immune defenses, resulting in immune evasion or autoimmunity. Furthermore, specific host reactivity was also detected against the TSP1-free part of BmP53 in infected hamster sera. In conclusion, the TSP1 domain mimicry might help in studying the mechanisms of parasite-induced thrombocytopenia, with the TSP1-free truncate of the protein representing a potential safe candidate for future vaccine studies.

Inactivation of Babesia microti in red blood cells and platelet concentrates.

BACKGROUND: With an increasing number of recognized transfusion-transmitted (TT) babesiosis cases, Babesia microti is the most frequently TT parasite in the United States. We evaluated the inactivation of B. microti in red blood cells (RBCs) prepared in Optisol (AS-5) using amustaline and glutathione (GSH) and in platelet components (PCs) in 100% plasma using amotosalen and low-energy ultraviolet A (UVA) light. STUDY DESIGN AND METHODS: Individual RBCs and apheresis PCs were spiked with B. microti-infected hamster RBCs (iRBCs) to a final concentration of 106 iRBCs/mL and treated with the respective inactivation systems according to the manufacturer's instruction. Samples were collected before (control) and after (test) each treatment. Dilutions of the control samples to 10-6 were inoculated into hamsters, while the test samples were inoculated neat or at 10-1 dilution. At 3 and 5 weeks postinoculation, hamsters were evaluated for B. microti infection by microscopic observation of blood smears and 50% infectivity titers (ID50 ) were determined. Log reduction was calculated as control log ID50 minus test log ID50 . RESULTS: Parasitemia was detected in hamsters injected with as low as 100,000-fold diluted control samples, while no parasites were detectable in the blood smears of any hamsters receiving neat test samples. Mean log reduction was more than 5 log/mL by amustaline/GSH for RBCs and more than 4.5 log/mL by amotosalen/UVA for PCs. CONCLUSION: B. microti was inactivated to the limit of detection in RBCs and PCs after the respective inactivation treatment. Complete inactivation of B. microti was achieved in this animal infectivity model, and pathogen reduction treatment inhibited transmission of infection.

Platelets activate a pathogenic response to blood-stage Plasmodium infection but not a protective immune response.

Clinical studies indicate that thrombocytopenia correlates with the development of severe falciparum malaria, suggesting that platelets either contribute to control of parasite replication, possibly as innate parasite killer cells or function in eliciting pathogenesis. Removal of platelets by anti-CD41 mAb treatment, platelet inhibition by aspirin, and adoptive transfer of wild-type (WT) platelets to CD40-KO mice, which do not control parasite replication, resulted in similar parasitemia compared with control mice. Human platelets at a physiologic ratio of 1 platelet to 9 red blood cells (RBCs) did not inhibit the in vitro development or replication of blood-stage Plasmodium falciparum The percentage of Plasmodium-infected (iRBCs) with bound platelets during the ascending parasitemia in Plasmodium chabaudi- and Plasmodium berghei-infected mice and the 48-hour in vitro cycle of P falciparum was <10%. P chabaudi and P berghei iRBCs with apoptotic parasites (TdT+) exhibited minimal platelet binding (<5%), which was similar to nonapoptotic iRBCs. These findings collectively indicate platelets do not kill bloodstage Plasmodium at physiologically relevant effector-to-target ratios. P chabaudi primary and secondary parasitemia was similar in mice depleted of platelets by mAb-injection just before infection, indicating that activation of the protective immune response does not require platelets. In contrast to the lack of an effect on parasite replication, adoptive transfer of WT platelets to CD40-KO mice, which are resistant to experimental cerebral malaria, partially restored experimental cerebral malaria mortality and symptoms in CD40-KO recipients, indicating platelets elicit pathogenesis and platelet CD40 is a key molecule.

Replication of Toxoplasma gondii in chicken erythrocytes and thrombocytes compared to macrophages.

Toxoplasma (T.) gondii is able to infect various cell types in different hosts. The replication of this parasite within different peripheral mononuclear blood cell populations in chicken has not yet been fully understood. Aim of the present study was to investigate the impact of chicken erythrocytes and thrombocytes as potential host cells for T. gondii. Cultures of primary avian erythrocytes and thrombocytes were inoculated with tachyzoites of T. gondii type II strain ME49. Parasite replication was detected by a quantitative real-time PCR at different times postinoculation until 24 or 48 h, respectively, displaying long-term investigations for the chosen cultures. The parasite replication curve showed a continuous decrease of parasite stages in erythrocytes and thrombocytes. Observations by light microscopy showed massive destruction for both cell populations. Few macrophages in between the infected thrombocytes were viable during the investigation period and showed internalised tachyzoites by confocal laser scanning microscopy. These findings show that T. gondii is not capable of replication in chicken erythrocytes and thrombocytes; therefore, both cannot be considered as potential host cells. In further consequence, monocyte-derived macrophages seem to be the key to the dissemination mechanisms for T. gondii in chicken.

The Gametocytes of Leucocytozoon sabrazesi Infect Chicken Thrombocytes, Not Other Blood Cells.

Leucocytozoon parasites infect a large number of avian hosts, including domestic chicken, and cause significant economical loss to the poultry industry. Although the transmission stages of the parasites were observed in avian blood cells more than a century ago, the specific host cell type(s) that the gametocytes infect remain uncertain. Because all the avian blood cells, including red blood cells (RBCs), are nucleated, and the developing parasites dramatically change the morphology of the infected host cells, it has been difficult to identify Leucocytozoon infected host cell(s). Here we use cell-type specific antibodies to investigate the identities of the host cells infected by Leucocytozoon sabrazesi gametocytes. Anti-RBC antibodies stained RBCs membrane strongly, but not the parasite-infected cells, ruling out the possibility of RBCs being the infected host cells. Antibodies recognizing various leukocytes including heterophils, monocytes, lymphocytes, and macrophages did not stain the infected cells either. Antisera raised against a peptide of the parasite cytochrome B (CYTB) stained parasite-infected cells and some leukocytes, particularly cells with a single round nucleus as well as clear/pale cytoplasm suggestive of thrombocytes. Finally, a monoclonal antibody known to specifically bind chicken thrombocytes also stained the infected cells, confirming that L. sabrazesi gametocytes develop within chicken thrombocytes. The identification of L. sabrazesi infected host cell solves a long unresolved puzzle and provides important information for studying parasite invasion of host cells and for developing reagents to interrupt parasite transmission.

Evidence of meaningful levels of Trypanosoma cruzi in platelet concentrates from seropositive blood donors.

BACKGROUND: According to the reported cases of transfusion-acquired Trypanosoma cruzi infection, the risk of T. cruzi transfusion transmission appears to be higher with platelet (PLT) products than with other blood components. The aim of this study was to investigate by quantitative real-time polymerase chain reaction (qPCR) the parasitic load detected in leukoreduced plasma and PLT concentrates collected by apheresis from seropositive T. cruzi blood donors and compare them with peripheral whole blood (WB). STUDY DESIGN AND METHODS: During 2011 to 2013, a prospective study was carried out in a group of blood donors originating from Chagas-endemic areas but who are now living on the island of Majorca, Spain. Leukoreduced plasma and PLT concentrates were collected by apheresis from seropositive blood donors with detectable parasitemias in peripheral WB. RESULTS: Seropositivity was found in 23 of 1201 donors studied (1.9%), and T. cruzi DNA with less than 1 parasite equivalent/mL was detected in peripheral WB in 60.86% (14 of 23) of these. The study in blood components obtained by apheresis from these donors showed that T. cruzi DNA with a mean ± SD parasitic load of 5.33 ± 6.12 parasite equivalents/mL was detected in 100% of the PLT concentrate samples. Parasite DNA was undetectable in the extract taken from plasma collected from donors with a positive qPCR in peripheral WB. CONCLUSION: The higher parasitic load found in PLT concentrates compared to plasma and peripheral WB would explain the higher transfusion transmission risk of Chagas disease associated with PLT transfusions described in the reported cases of transfusion-acquired T. cruzi infection.

Immune-relevant thrombocytes of common carp undergo parasite-induced nitric oxide-mediated apoptosis.

Common carp thrombocytes account for 30-40% of peripheral blood leukocytes and are abundant in the healthy animals' spleen, the thrombopoietic organ. We show that, ex vivo, thrombocytes from healthy carp express a large number of immune-relevant genes, among which several cytokines and Toll-like receptors, clearly pointing at immune functions of carp thrombocytes. Few studies have described the role of fish thrombocytes during infection. Carp are natural host to two different but related protozoan parasites, Trypanoplasma borreli and Trypanosoma carassii, which reside in the blood and tissue fluids. We used the two parasites to undertake controlled studies on the role of fish thrombocytes during these infections. In vivo, but only during infection with T. borreli, thrombocytes were massively depleted from the blood and spleen leading to severe thrombocytopenia. Ex vivo, addition of nitric oxide induced a clear and rapid apoptosis of thrombocytes from healthy carp, supporting a role for nitric oxide-mediated control of immune-relevant thrombocytes during infection with T. borreli. The potential advantage for parasites to selectively deplete the host of thrombocytes via nitric oxide-induced apoptosis is discussed.

Schistosomes versus platelets.

Schistosomes are parasitic platyhelminths that currently infect >200million people and cause the chronic debilitating disease schistosomiasis. While these large intravascular parasites can disturb blood flow, they do not appear to activate platelets and provoke thrombus formation. Host-interactive tegumental molecules have been proposed to be important in this regard. For example, tegumental apyrase, SmATPDase1 can degrade the platelet-activating molecule ADP in the extracellular environment. The parasites themselves can produce prostaglandins (or may induce prostaglandin production by host cells) which could inhibit platelet aggregation. Additional tegumental proteins have been proposed to impede the coagulation cascade and to promote fibrinolysis. Platelets have been shown to be directly toxic to schistosomes. Platelets recovered from infected rats are able to kill larval parasites in culture and platelets obtained at later times post-infection are generally better at killing. Even platelets from uninfected rats can rapidly kill larval schistosomes if first exposed to a variety of activators (such as: serum from infected rats, the IgE fraction of that serum, C-reactive protein, cytokines (TNFα or TNFß)). Passive transfer of stimulated platelets can protect rats against a challenge schistosome infection. Cytokines (TNFα, TNFß, IFNγ or IL-6) have been shown to similarly promote normal human platelet killing of schistosomes in vitro. Platelet antimicrobial effector molecules (e.g. platelet microbicidal proteins) may mediate such killing. While platelets can be protective against schistosomes following infection of humans and mice, platelet numbers decline (but not so in the non-permissive rat host) and coagulopathy becomes more apparent as schistosome-induced pathology increases.

Novel nitro(triazole/imidazole)-based heteroarylamides/sulfonamides as potential antitrypanosomal agents.

We have previously shown that 3-nitro-1H-1,2,4-triazole-based arylamides and arylsulfonamides demonstrate significant activity in vitro against Trypanosoma cruzi, the causative parasite of Chagas disease. More importantly, several such analogs displayed significant antichagasic activity in vivo, superior to that of benznidazole, the current clinical standard. We now report the synthesis and in vitro evaluation of a small series of novel nitro(triazole/imidazole)-based heteroarylamides/sulfonamides (including 3-nitrotriazole-, 2- and 4-nitroimidazole-based compounds) as potential antitrypanosomal agents. All nitrotriazoles displayed significant growth inhibitory properties against T. cruzi with the most potent generating IC50 values of <1 µM and up to >1400-fold selectivity toward the parasite. The 2-nitroimidazole-based derivatives were moderately active against T. cruzi and displayed selectivity <50, while the 4-nitroimidazoles were mostly inactive. Several 3-nitrotriazole-based analogs showed activity against Trypanosoma brucei rhodesiense but none of the tested compounds displayed activity toward Leishmania donovani. From the detailed SARs presented here, we identified the 3-nitrotriazole-based chlorinated thiophene/benzothiophene sulfonamides/amides as being the most active antichagasic compounds, displaying up to 14-fold higher potency against T. cruzi than the reference compound benznidazole.

In vitro antiparasitic activity of new thiosemicarbazones in strains of Trypanosoma cruzi.

In this study thiosemicarbazones derivatives of 5-[(trifluoromethyl)phenylthio]-2-furaldehyde were synthesized and evaluated in terms of their efficiency in challenging the growth of epimastigote forms of Trypanosoma cruzi, the etiological agent of Chagas' disease. A number of compounds were synthesized from 5-bromo-2-furfuraldehyde using nucleophilic aromatic substitution, with a series of trifluoromethyl thiolates, followed by condensation reactions with thiosemicarbazide. Their molecular structures were determined by (1)H, (13)C and (19)F NMR, MS and IR spectroscopy. When tested with T. cruzi, they showed a stronger reaction, similar to nifurtimox and benznidazole, with the 5-[nitro-4-(trifluoromethyl)phenyltio]-2-furaldehyde thiosemicarbazone (compound 4) showing the highest antiparasitic activity. This improved activity may be explained due to the nitro group present in the molecule, which potentiates its activity. The thiosemicarbazone derivatives in this study showed no apoptosis in platelets or monocytes, nor did they induce platelet activation. The trypanocidal activity of these substances represents a good starting point for a medicinal chemistry program aimed at therapy for Chagas' disease.

Proteome changes in platelets after pathogen inactivation--an interlaboratory consensus.

Pathogen inactivation (PI) of platelet concentrates (PCs) reduces the proliferation/replication of a large range of bacteria, viruses, and parasites as well as residual leucocytes. Pathogen-inactivated PCs were evaluated in various clinical trials showing their efficacy and safety. Today, there is some debate over the hemostatic activity of treated PCs as the overall survival of PI platelets seems to be somewhat reduced, and in vitro measurements have identified some alterations in platelet function. Although the specific lesions resulting from PI of PCs are still not fully understood, proteomic studies have revealed potential damages at the protein level. This review merges the key findings of the proteomic analyses of PCs treated by the Mirasol Pathogen Reduction Technology, the Intercept Blood System, and the Theraflex UV-C system, respectively, and discusses the potential impact on the biological functions of platelets. The complementarities of the applied proteomic approaches allow the coverage of a wide range of proteins and provide a comprehensive overview of PI-mediated protein damage. It emerges that there is a relatively weak impact of PI on the overall proteome of platelets. However, some data show that the different PI treatments lead to an acceleration of platelet storage lesions, which is in agreement with the current model of platelet storage lesion in pathogen-inactivated PCs. Overall, the impact of the PI treatment on the proteome appears to be different among the PI systems. Mirasol impacts adhesion and platelet shape change, whereas Intercept seems to impact proteins of intracellular platelet activation pathways. Theraflex influences platelet shape change and aggregation, but the data reported to date are limited. This information provides the basis to understand the impact of different PI on the molecular mechanisms of platelet function. Moreover, these data may serve as basis for future developments of PI technologies for PCs. Further studies should address the impact of both the PI and the storage duration on platelets in PCs because PI may enable the extension of the shelf life of PCs by reducing the bacterial contamination risk.