Thrombotic microangiopathy associated with Plasmodium vivax malaria

Uncomplicated Plasmodium vivax malaria: mapping the proteome from circulating platelets

Background

Thrombocytopenia is frequent in Plasmodium vivax malaria but the role of platelets in pathogenesis is unknown. Our study explores the platelet (PLT) proteome from uncomplicated P. vivax patients, to fingerprint molecular pathways related to platelet function. Plasma levels of Platelet factor 4 (PF4/CXCL4) and Von Willebrand factor (VWf), as well as in vitro PLTs—P. vivax infected erythrocytes (Pv-IEs) interactions were also evaluated to explore the PLT response and effect on parasite development.

Methods

A cohort of 48 patients and 25 healthy controls were enrolled. PLTs were purified from 5 patients and 5 healthy controls for Liquid Chromatography–Mass spectrometry (LC–MS/MS) analysis. Plasma levels of PF4/CXCL4 and VWf were measured in all participants. Additionally, P. vivax isolates (n = 10) were co-cultured with PLTs to measure PLT activation by PF4/CXCL4 and Pv-IE schizonts formation by light microscopy.

Results

The proteome from uncomplicated P. vivax patients showed 26 out of 215 proteins significantly decreased. PF4/CXCL4 was significantly decreased followed by other proteins involved in platelet activation, cytoskeletal remodeling, and endothelial adhesion, including glycoprotein V that was significantly decreased in thrombocytopenic patients. In contrast, acute phase proteins, including SERPINs and Amyloid Serum A1 were increased. High levels of VWf in plasma from patients suggested endothelial activation while PF4/CXCL4 plasma levels were similar between patients and controls. Interestingly, high levels of PF4/CXCL4 were released from PLTs—Pv-IEs co-cultures while Pv-IEs schizont formation was inhibited.

Conclusions

The PLT proteome analyzed in this study suggests that PLTs actively respond to P. vivax infection. Altogether, our findings suggest important roles of PF4/CXCL4 during uncomplicated P. vivax infection through a possible intracellular localization. Our study shows that platelets are active responders to P. vivax infection, inhibiting intraerythrocytic parasite development. Future studies are needed to further investigate the molecular pathways of interaction between platelet proteins found in this study and host response, which could affect parasite control as well as disease progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12014-021-09337-7.

Malaria and acute kidney injury

Malaria is a parasitic infection transmitted by mosquitos, resulting in significant morbidity and mortality. It affects 212 million worldwide, causing death in up to 303,000 children annually. In the USA, up to 1700 people are affected yearly. Although the prevalence in developed countries is less than in developing countries, travelers from low transmission areas, and those from endemic areas who later return, are very susceptible to malaria and its complications. Severe malaria can cause significant multiorgan dysfunction including acute kidney injury (AKI). The pathogenesis is not clearly understood but proposed mechanisms include acute tubular necrosis (ATN) due to impediments in renal microcirculation, infection-triggered proinflammatory reactions within the kidney, and metabolic disturbances. Providers must consider malarial infection in cases of AKI in someone with a travel history, as early recognition and treatment are crucial to improving outcomes. This article will review malaria-induced AKI in order to provide a better understanding of this infection's effect on the kidneys.

Epidemiology, drug resistance, and pathophysiology of Plasmodium vivax malaria

Malaria, caused by the protozoan parasites of the genus Plasmodium, is a major health problem in many countries of the world. Five parasite species namely, Plasmodium falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi, cause malaria in humans. Of these, P. falciparum and P. vivax are the most prevalent and account for the majority of the global malaria cases. In most areas of Africa, P. vivax infection is essentially absent because of the inherited lack of Duffy antigen receptor for chemokines on the surface of red blood cells that is involved in the parasite invasion of erythrocytes. Therefore, in Africa, most malaria infections are by P. falciparum and the highest burden of P. vivax infection is in Southeast Asia and South America. Plasmodium falciparum is the most virulent and as such, it is responsible for the majority of malarial mortality, particularly in Africa. Although, P. vivax infection has long been considered to be benign, recent studies have reported life-threatening consequences, including acute respiratory distress syndrome, cerebral malaria, multi-organ failure, dyserythropoiesis and anaemia. Despite exhibiting low parasite biomass in infected people due to parasite's specificity to infect only reticulocytes, P. vivax infection triggers higher inflammatory responses and exacerbated clinical symptoms than P. falciparum, such as fever and chills. Another characteristic feature of P. vivax infection, compared to P. falciparum infection, is persistence of the parasite as dormant liver-stage hypnozoites, causing recurrent episodes of malaria. This review article summarizes the published information on P. vivax epidemiology, drug resistance and pathophysiology.

Plasmodium vivax Biology: Insights Provided by Genomics, Transcriptomics and Proteomics

During the last decade, the vast omics field has revolutionized biological research, especially the genomics, transcriptomics and proteomics branches, as technological tools become available to the field researcher and allow difficult question-driven studies to be addressed. Parasitology has greatly benefited from next generation sequencing (NGS) projects, which have resulted in a broadened comprehension of basic parasite molecular biology, ecology and epidemiology. Malariology is one example where application of this technology has greatly contributed to a better understanding of Plasmodium spp. biology and host-parasite interactions. Among the several parasite species that cause human malaria, the neglected Plasmodium vivax presents great research challenges, as in vitro culturing is not yet feasible and functional assays are heavily limited. Therefore, there are gaps in our P. vivax biology knowledge that affect decisions for control policies aiming to eradicate vivax malaria in the near future. In this review, we provide a snapshot of key discoveries already achieved in P. vivax sequencing projects, focusing on developments, hurdles, and limitations currently faced by the research community, as well as perspectives on future vivax malaria research.

Transdermal delivery of tadalafil using a novel formulation

The aim of this work was to investigate the transdermal gel loaded with tadalafil, a practically insoluble selective phosphodiesterase-5 inhibitor (PDE5) in order to improve the solubility and bioavailability. The solubility of tadalafil in mixed solution of hydroxypropyl-β-cyclodextrin (HPCD), polyethylene glycol (PEG) 400 and tween 80 (T2 solution) was 260.8 ± 4.3 µg/mL and that of tadalafil in modified T2 (M-T2) solution, which tadalafil was dissolved in 20% (w/v) HPCD at first and then mixture solutions of PEG 400 and tween 80 were added, was increased to 344.9 ± 30.6 µg/mL. Four gel formulae were prepared, subsequently in vitro and in vivo skin permeation studies were carried out. Interestingly, tadalafil gel in M-T2 and oleic acid (OA) (F3) could promote the percutaneous absorption of tadalafil by 179.4% in vitro and increase AUC by 223% in vivo compared with tadalafil gel in the absence of M-T2 and OA (F1). Also, there was a finding that tadalafil gel in M-T2 and OA did not cause dermal irritations in an experimental animal.

Parasite biomass-related inflammation, endothelial activation, microvascular dysfunction and disease severity in vivax malaria

Plasmodium vivax can cause severe malaria, however its pathogenesis is poorly understood. In contrast to P. falciparum, circulating vivax parasitemia is low, with minimal apparent sequestration in endothelium-lined microvasculature, and pathogenesis thought unrelated to parasite biomass. However, the relationships between vivax disease-severity and total parasite biomass, endothelial autocrine activation and microvascular dysfunction are unknown. We measured circulating parasitemia and markers of total parasite biomass (plasma parasite lactate dehydrogenase [pLDH] and PvLDH) in adults with severe (n = 9) and non-severe (n = 53) vivax malaria, and examined relationships with disease-severity, endothelial activation, and microvascular function. Healthy controls and adults with non-severe and severe falciparum malaria were enrolled for comparison. Median peripheral parasitemia, PvLDH and pLDH were 2.4-fold, 3.7-fold and 6.9-fold higher in severe compared to non-severe vivax malaria (p = 0.02, p = 0.02 and p = 0.015, respectively), suggesting that, as in falciparum malaria, peripheral P. vivax parasitemia underestimates total parasite biomass, particularly in severe disease. P. vivax schizonts were under-represented in peripheral blood. Severe vivax malaria was associated with increased angiopoietin-2 and impaired microvascular reactivity. Peripheral vivax parasitemia correlated with endothelial activation (angiopoietin-2, von-Willebrand-Factor [VWF], E-selectin), whereas markers of total vivax biomass correlated only with systemic inflammation (IL-6, IL-10). Activity of the VWF-cleaving-protease, ADAMTS13, was deficient in proportion to endothelial activation, IL-6, thrombocytopenia and vivax disease-severity, and associated with impaired microvascular reactivity in severe disease. Impaired microvascular reactivity correlated with lactate in severe vivax malaria. Findings suggest that tissue accumulation of P. vivax may occur, with the hidden biomass greatest in severe disease and capable of mediating systemic inflammatory pathology. The lack of association between total parasite biomass and endothelial activation is consistent with accumulation in parts of the circulation devoid of endothelium. Endothelial activation, associated with circulating parasites, and systemic inflammation may contribute to pathology in vivax malaria, with microvascular dysfunction likely contributing to impaired tissue perfusion.

Hemolytic uremic syndrome associated with Plasmodium vivax malaria successfully treated with plasma exchange

We report a case of hemolytic uremic syndrome (HUS) in an adult patient with Plasmodium vivax malaria. The patient presented with worsening anemia, persistent thrombocytopenia and acute kidney injury. HUS was diagnosed based on the high serum lactate dehydrogenase, elevated reticulocyte count and presence of schistocytes on peripheral blood smear. Kidney biopsy showed features of thrombotic microangiopathy. Complete hematological remission was achieved after five sessions of therapeutic plasma exchange. Renal function partially recovered and stabilized at discharge. Vivax malaria, generally considered benign, may be rarely associated with HUS.

Severe disease in children hospitalized with a diagnosis of Plasmodium vivax in south-eastern Pakistan

Background

Infection by Plasmodium vivax has been considered rarely threatening to life, but recent studies challenge this notion. This study documented the frequency and character of severe illness in paediatric patients admitted to a hospital in south-eastern Pakistan with a laboratory-confirmed diagnosis of vivax malaria.

Methods

An observational study of all 180 paediatric patients admitted with any diagnosis of malaria during 2010 was conducted: 128 P. vivax; 48 Plasmodium falciparum; and four mixed infections of these species. Patients were classified as having severe illness with any of the following indicators: Glascow coma scale <11; ≥2 convulsions; haemoglobin <5g/dL; thrombocytes <50,000/mL; blood glucose <45mg%; >70 breaths/min; or intravenous anti-malarial therapy. Additionally, 64 patients with a diagnosis of vivax malaria were treated during 2009, and the 21 of these having severe illness were included in analyses of the frequency and character of severe illness with that diagnosis.

Results

During 2010, 39 (31%) or 37 (77%) patients with a diagnosis of P. vivax or P. falciparum were classified as having severe disease. Including the 2009 records of 64 patients having vivax malaria, a total of 60 (31%) patients with severe illness and a diagnosis of P. vivax were available. Altered mental status (Glascow coma scale score <11; or ≥2 convulsions) dominated at 54% of the 83 indicators of severe illness manifest among the patients with vivax malaria, as was true among the 37 children with a diagnosis of falciparum malaria and being severely ill; 58% of the 72 indicators of severe disease documented among them. No statistically significant difference appeared in frequencies of any other severe disease indicators between patients diagnosed with vivax or falciparum malaria. Despite such similarities, a diagnosis of falciparum malaria nonetheless came with 3.8-fold (95% CI = 1.8-8.1) higher risk of presenting with severe illness, and 8.0-fold (95% CI = 2.1-31) greater likelihood of presenting with three or more severe disease indicators. Two patients did not survive hospitalization, one each with a diagnosis of falciparum or vivax malaria.

Conclusions

Vivax malaria caused a substantial burden of potentially life-threatening morbidity on a paediatric ward in a hospital in south-eastern Pakistan.

Thrombocytopenia in childhood malaria with special reference to P. vivax monoinfection: A study from Bikaner (Northwestern India)

Thrombocytopenia is commonly seen in Plasmodium vivax malaria, but its prognostic value has not been addressed in children. This prospective study included 676 admitted children of malaria [Plasmodium falciparum (Pf) monoinfection 262, Plasmodium vivax (Pv) monoinfection 380, and mixed (Pf + Pv) infection 34], in which thrombocytopenia (platelet count <150 × 10(3)/mm(3) on admission) was found in 442 (65.38%) children [Pf monoinfection 55.3% (145/262), Pv monoinfection 73.16% (278/380), and mixed infection 55.88% (19/34)]. The association of thrombocytopenia was statistically significant with Pv monoinfection [73.16% (278/380)] in comparison to either Pf monoinfection [55.34% (145/262); odds ratio (OR) = 2.199 (95% confidence interval (CI) 1.577-3.068), p < 0.0001] or mixed infection [55.88% (19/34); OR = 2.152 (95%CI 1.054-4.394), p = 0.032]. In Pv monoinfection, thrombocytopenia was highest in 0-5 years age group and subsequently decreased with advancing age, whereas in Pf monoinfection it was reverse. Severe thrombocytopenia (platelet count <20 × 10(3)/mm(3)) was present in 16.52% (73/442) children [Pv monoinfection 21.58% (60/278) and Pf monoinfection 8.97% (13/145)]. The risk of developing severe thrombocytopenia was also highest in Pv monoinfection [15.79% (60/380)] in comparison to Pf monoinfection [10.59% (13/262); OR = 3.591 (95%CI 1.928-6.690), p < 0.0001]. Bleeding manifestations were associated in 21.27% (94/442) children [Pf monoinfection 9.92% (26/262), Pv monoinfection 16.58% (63/380), and mixed malaria 14.71% (5/34)]. All the children having bleeding manifestations had thrombocytopenia but low platelet counts were not always associated with abnormal bleeding. The association of severe malaria was significantly more among children having Pv monoinfection with platelet counts <20 × 10(3)/mm(3) [OR = 2.569 (95%CI 1.196-5.517), p < 0.014] with specificity of 88.3% and positive predictive value of 85%. Till today, thrombocytopenia is not included in severe malaria criterion described by WHO, but when platelet counts <20 × 103/mm(3), we advocate it to include as one of the severe malaria criteria.

Acute glomerulonephritis: an unusual manifestation of Plasmodium vivax malaria

Long considered a benign infection, Plasmodium vivax is now increasingly recognised as a cause of severe and fatal malaria. Various atypical presentations of vivax malaria have been reported. This report highlights the occurrence of acute glomerulonephritis in a 7-year-old girl who presented with fever and vomiting. Peripheral smear examination demonstrated ring forms of P. vivax. OptiMAL test was positive for P. vivax and negative for Plasmodium falciparum. She was managed with antimalarial and antihypertensive drugs and made an uneventful recovery.

Clinical features of children hospitalized with malaria--a study from Bikaner, northwest India

Severe Plasmodium vivax malaria in adults has been reported from Bikaner (northwestern India) but the reports on children are scanty. This prospective study was done on 303 admitted children of malaria. The diagnosis was done by peripheral blood smear and rapid diagnostic test. Further confirmation of severe P. vivax monoinfection was done by polymerase chain reaction (PCR). The proportion of P. falciparum, P. vivax, and mixed (P. falciparum and P. vivax) infection was 61.01%, 33.99%, and 4.95%, respectively. Severe disease was present in 49.5% (150/303) children with malaria, with the risk greatest among P. vivax monoinfection (63.1% [65/103]) compared with P. falciparum, either alone (42.7% [79/185]; odds ratio [OR] = 2.3 [95% confidence interval (CI) = 1.40-3.76], P = 0.001) or mixed infections (40% [6/15]; OR = 2.57 [95% CI = 0.88-7.48]). In children < 5 years of age, the proportion of severe malaria attributable to P. vivax rose to 67.4% (31/46) compared with 30.4% (14/46) of P. falciparum (OR = 4.7 [95% CI = 2.6-8.6], P < 0.0001) and 2.2% (1/46) of mixed infection (OR = 92 [95% CI = 24.6-339.9], P < 0.0001). The proportion of patients having severe manifestations, which included severe anemia, thrombocytopenia, cerebral malaria, acute respiratory distress syndrome, hepatic dysfunction, renal dysfunction, abnormal bleeding was significantly high in association with P. vivax monoinfection in 0-5 year age group, while the same was significantly high in association with P. falciparum monoinfection in 5-10 year age group. Similarly P. vivax monoinfection had greatest propensity to cause multiorgan dysfunction in 0-5 year age group (34.1% [17/41], P < 0.0001) in comparison to P. falciparum monoinfection, which had similar propensity in 5-10 year age group (36.8% [35/95], P = 0.039). Plasmodium vivax monoinfection was almost equally serious to cause significant mortality in comparison to P. falciparum (case fatality rate of severe P. vivax was 3.9% versus 3.2% of severe P. falciparum malaria; P = 1.0). This study reaffirms the evidence of severe P. vivax malaria in children in Bikaner.

The pathophysiology of vivax malaria

Long considered a benign infection, Plasmodium vivax is now recognized as a cause of severe and fatal malaria, despite its low parasite biomass, the increased deformability of vivax-infected red blood cells and an apparent paucity of parasite sequestration. Severe anemia is associated with recurrent bouts of hemolysis of predominantly uninfected erythrocytes with increased fragility, and lung injury is associated with inflammatory increases in alveolar-capillary membrane permeability. Although rare, vivax-associated coma challenges our understanding of pathobiology caused by Plasmodium spp. Host and parasite factors contribute to the risk of severe disease, and comorbidities might contribute to vivax mortality. In this review, we discuss potential mechanisms underlying the syndromes of uncomplicated and severe vivax malaria, identifying key areas for future research.