Elevated Cerebrospinal Fluid Tau Protein Concentrations on Admission Are Associated With Long-term Neurologic and Cognitive Impairment in Ugandan Children With Cerebral Malaria

Linking Cerebral Malaria Pathogenesis to APOE-Mediated Amyloidosis: Observations and Hypothesis

Although most children with cerebral malaria fully recover, more than a fifth of the survivors develop post-discharge neurodevelopmental sequelae suggestive of advanced neuronal injury. However, the cerebral molecular processes initiating neurological dysfunction in cerebral malaria are still debatable. In this article, we explore available data and hypothesise that cerebral malaria might be linked to APOE-mediated amyloidosis, one of the pathological processes associated with Alzheimer's disease. If our hypothesis is tested and found to be true, it could have far-reaching implications for what we know about cerebral malaria pathogenesis.

Apolipoprotein-E4: risk of severe malaria and mortality and cognitive impairment in pediatric cerebral malaria

BACKGROUND

The relationship of apolipoprotein-E4 (APOE4) to mortality and cognition after severe malaria in children is unknown.

METHODS

APOE genotyping was performed in children with cerebral malaria (CM, n = 261), severe malarial anemia (SMA, n = 224) and community children (CC, n = 213). Cognition was assessed over 2-year follow-up.

RESULTS

A greater proportion of children with CM or SMA than CC had APOE4 (n = 162, 31.0%; n = 142, 31.7%; n = 103, 24.2%, respectively, p = 0.02), but no difference was seen in APOE3 (n = 310, 59.4%; n = 267, 59.6%; n = 282, 66.2%, respectively, p = 0.06), or APOE2 (n = 50, 9.6%; n = 39, 8.7%; and n = 41, 9.6%, respectively, p = 0.87). APOE4 was associated with increased mortality in CM (odds ratio, 2.28; 95% CI, 1.01, 5.11). However, APOE4 was associated with better long-term cognition (ß, 0.55; 95% CI, 0.04, 1.07, p = 0.04) and attention (ß 0.78; 95% CI, 0.26, 1.30, p = 0.004) in children with CM < 5 years old, but worse attention (ß, -0.90; 95% CI, -1.69, -0.10, p = 0.03) in children with CM ≥ 5 years old. Among children with CM, risk of post-discharge malaria was increased with APOE4 and decreased with APOE3.

CONCLUSIONS

APOE4 is associated with higher risk of CM or SMA and mortality in children with CM, but better long-term cognition in CM survivors <5 years of age.

A human pluripotent stem cell-derived in vitro model of the blood-brain barrier in cerebral malaria

BACKGROUND

Blood-brain barrier (BBB) disruption is a central feature of cerebral malaria (CM), a severe complication of Plasmodium falciparum (Pf) infections. In CM, sequestration of Pf-infected red blood cells (Pf-iRBCs) to brain endothelial cells combined with inflammation, hemolysis, microvasculature obstruction and endothelial dysfunction mediates BBB disruption, resulting in severe neurologic symptoms including coma and seizures, potentially leading to death or long-term sequelae. In vitro models have advanced our knowledge of CM-mediated BBB disruption, but their physiological relevance remains uncertain. Using human induced pluripotent stem cell-derived brain microvascular endothelial cells (hiPSC-BMECs), we aimed to develop a novel in vitro model of the BBB in CM, exhibiting enhanced barrier properties.

METHODS

hiPSC-BMECs were co-cultured with HB3var03 strain Pf-iRBCs up to 9 h. Barrier integrity was measured using transendothelial electrical resistance (TEER) and sodium fluorescein permeability assays. Localization and expression of tight junction (TJ) proteins (occludin, zonula occludens-1, claudin-5), cellular adhesion molecules (ICAM-1, VCAM-1), and endothelial surface markers (EPCR) were determined using immunofluorescence imaging (IF) and western blotting (WB). Expression of angiogenic and cell stress markers were measured using multiplex proteome profiler arrays.

RESULTS

After 6-h of co-culture with Pf-iRBCs, hiPSC-BMECs showed reduced TEER and increased sodium fluorescein permeability compared to co-culture with uninfected RBCs, indicative of a leaky barrier. We observed disruptions in localization of occludin, zonula occludens-1, and claudin-5 by IF, but no change in protein expression by WB in Pf-iRBC co-cultures. Expression of ICAM-1 and VCAM-1 but not EPCR was elevated in hiPSC-BMECs with Pf-iRBC co-culture compared to uninfected RBC co-culture. In addition, there was an increase in expression of angiogenin, platelet factor-4, and phospho-heat shock protein-27 in the Pf-iRBCs co-culture compared to uninfected RBC co-culture.

CONCLUSION

These findings demonstrate the validity of our hiPSC-BMECs based model of the BBB, that displays enhanced barrier integrity and appropriate TJ protein localization. In the hiPSC-BMEC co-culture with Pf-iRBCs, reduced TEER, increased paracellular permeability, changes in TJ protein localization, increase in expression of adhesion molecules, and markers of angiogenesis and cellular stress all point towards a novel model with enhanced barrier properties, suitable for investigating pathogenic mechanisms underlying BBB disruption in CM.

Plasmodium knowlesi infection is associated with elevated circulating biomarkers of brain injury and endothelial activation

Introduction

Malaria remains a major public health concern with substantial morbidity and mortality worldwide. In Malaysia, the emergence of Plasmodium knowlesi has led to a surge in zoonotic malaria cases and deaths in recent years. Signs of cerebral involvement have been observed in a non-comatose, fatal case of severe knowlesi infection, but the potential impact of this malaria species on the brain remains underexplored. To address this gap, we investigated circulating levels of brain injury, inflammation, and vascular biomarkers in a cohort of knowlesi-infected patients and controls.

Methods

Archived plasma samples from 19 patients with confirmed symptomatic knowlesi infection and 19 healthy, age-matched controls from Peninsular Malaysia were analysed. A total of 52 plasma biomarkers of brain injury, inflammation, and vascular activation were measured using Luminex and SIMOA assays. Wilcoxon tests were used to examine group differences, and biomarker profiles were explored through hierarchical clustering heatmap analysis.

Results

Bonferroni-corrected analyses revealed significantly elevated brain injury biomarker levels in knowlesi-infected patients, including S100B (p<0.0001), Tau (p=0.0007), UCH-L1 (p<0.0001), αSyn (p<0.0001), Park7 (p=0.0006), NRGN (p=0.0022), and TDP-43 (p=0.005). Compared to controls, levels were lower in the infected group for BDNF (p<0.0001), CaBD (p<0.0001), CNTN1 (p<0.0001), NCAM-1 (p<0.0001), GFAP (p=0.0013), and KLK6 (p=0.0126). Hierarchical clustering revealed distinct group profiles for circulating levels of brain injury and vascular activation biomarkers.

Conclusions

Our findings highlight for the first time the impact of Plasmodium knowlesi infection on the brain, with distinct alterations in cerebral injury and endothelial activation biomarker profiles compared to healthy controls. Further studies are warranted to investigate the pathophysiology and clinical significance of these altered surrogate markers, through both neuroimaging and long-term neurocognitive assessments.

Malaria

Malaria is resurging in many African and South American countries, exacerbated by COVID-19-related health service disruption. In 2021, there were an estimated 247 million malaria cases and 619 000 deaths in 84 endemic countries. Plasmodium falciparum strains partly resistant to artemisinins are entrenched in the Greater Mekong region and have emerged in Africa, while Anopheles mosquito vectors continue to evolve physiological and behavioural resistance to insecticides. Elimination of Plasmodium vivax malaria is hindered by impractical and potentially toxic antirelapse regimens. Parasitological diagnosis and treatment with oral or parenteral artemisinin-based therapy is the mainstay of patient management. Timely blood transfusion, renal replacement therapy, and restrictive fluid therapy can improve survival in severe malaria. Rigorous use of intermittent preventive treatment in pregnancy and infancy and seasonal chemoprevention, potentially combined with pre-erythrocytic vaccines endorsed by WHO in 2021 and 2023, can substantially reduce malaria morbidity. Improved surveillance, better access to effective treatment, more labour-efficient vector control, continued drug development, targeted mass drug administration, and sustained political commitment are required to achieve targets for malaria reduction by the end of this decade.

Blood biomarkers of neuronal injury in paediatric cerebral malaria and severe malarial anaemia

Persistent neurodisability is a known complication in paediatric survivors of cerebral malaria and severe malarial anaemia. Tau, ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein have proven utility as biomarkers that predict adverse neurologic outcomes in adult and paediatric disorders. In paediatric severe malaria, elevated tau is associated with mortality and neurocognitive complications. We aimed to investigate whether a multi-analyte panel including ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein can serve as biomarkers of brain injury associated with mortality and neurodisability in cerebral malaria and severe malarial anaemia. In a prospective cohort study of Ugandan children, 18 months to 12 years of age with cerebral malaria (n = 182), severe malarial anaemia (n = 158), and asymptomatic community children (n = 118), we measured admission blood levels of ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein. We investigated differences in biomarker levels, associations with mortality, blood-brain barrier integrity, neurodeficits and cognitive Z-scores in survivors up to 24-month follow-up. Admission ubiquitin C-terminal hydrolase-L1 levels were elevated >95th percentile of community children in 71 and 51%, and neurofilament-light chain levels were elevated >95th percentile of community children in 40 and 37% of children with cerebral malaria and severe malarial anaemia, respectively. Glial fibrillary acidic protein was not elevated in disease groups compared with controls. In cerebral malaria, elevated neurofilament-light chain was observed in 16 children who died in hospital compared with 166 survivors (P = 0.01); elevations in ubiquitin C-terminal hydrolase-L1 levels were associated with degree of blood-brain barrier disruption (P = 0.01); and the % predictive value for neurodeficits over follow-up (discharge, 6-, 12-, and 24 months) increased for ubiquitin C-terminal hydrolase-L1 (60, 67, 72, and 83), but not neurofilament-light chain (65, 68, 60, and 67). In cerebral malaria, elevated ubiquitin C-terminal hydrolase-L1 was associated with worse memory scores in children <5 years at malaria episode who crossed to over 5 years old during follow-up cognitive testing [β -1.13 (95% confidence interval -2.05, -0.21), P = 0.02], and elevated neurofilament-light chain was associated with worse attention in children ≥5 years at malaria episode and cognitive testing [β -1.08 (95% confidence interval -2.05, -1.05), P = 0.03]. In severe malarial anaemia, elevated ubiquitin C-terminal hydrolase-L1 was associated with worse attention in children <5 years at malaria episode and cognitive testing [β -0.42 (95% confidence interval -0.76, -0.07), P = 0.02]. Ubiquitin C-terminal hydrolase-L1 and neurofilament-light chain levels are elevated in paediatric cerebral malaria and severe malarial anaemia. In cerebral malaria, elevated neurofilament-light chain is associated with mortality whereas elevated ubiquitin C-terminal hydrolase-L1 is associated with blood-brain barrier dysfunction and neurodeficits over follow-up. In cerebral malaria, both markers are associated with worse cognition, while in severe malarial anaemia, only ubiquitin C-terminal hydrolase-L1 is associated with worse cognition.

Effects of anti-tau immunotherapy on reactive microgliosis, cerebral endotheliopathy, and cognitive function in an experimental model of cerebral malaria

Cerebral malaria (CM), a potentially fatal encephalopathy caused primarily by infection with Plasmodium falciparum, results in long-term adverse neuro-psychiatric sequelae. Neural cell injury contributes to the neurological deficits observed in CM. Abnormal regulation of tau, an axonal protein pathologically associated with the formation of neurofibrillary lesions in neurodegenerative diseases, has been linked to inflammation and cerebral microvascular compromise and has been reported in human and experimental CM (ECM). Immunotherapy with a monoclonal antibody to pathological tau (PHF-1 mAB) in experimental models of neurodegenerative diseases has been reported to mitigate cognitive decline. We investigated whether immunotherapy with PHF-1 mAB prevented cerebral endotheliopathy, neural cell injury, and neuroinflammation during ECM. Using C57BL/6 mice infected with either Plasmodium berghei ANKA (PbA), which causes ECM, Plasmodium berghei NK65 (PbN), which causes severe malaria, but not ECM, or uninfected mice (Un), we demonstrated that when compared to PbN infection or uninfected mice, PbA infection resulted in significant memory impairment at 6 days post-infection, in association with abnormal tau phosphorylation at Ser202 /Thr205 (pSer202 /Thr205 ) and Ser396-404 (pSer396-404 ) in mouse brains. ECM also resulted in significantly higher expression of inflammatory markers, in microvascular congestion, and glial cell activation. Treatment with PHF-1 mAB prevented PbA-induced cognitive impairment and was associated with significantly less vascular congestion, neuroinflammation, and neural cell activation in mice with ECM. These findings suggest that abnormal regulation of tau protein contributes to cerebral vasculopathy and is critical in the pathogenesis of neural cell injury during CM. Tau-targeted therapies may ameliorate the neural cell damage and subsequent neurocognitive impairment that occur during disease.

Efficacy of artesunate combined with Atractylodes lancea or Prabchompoothaweep remedy extracts as adjunctive therapy for the treatment of cerebral malaria

BACKGROUND

Cerebral malaria is one of the most serious complications of Plasmodium infection and causes behavioral changes. However, current antimalarial drugs have shown poor outcomes. Therefore, new antimalarials with neuroprotective effects are urgently needed. This study aimed to evaluate the effects of selected extracts as monotherapy or adjunctive therapy with artesunate on antimalarial, anti-inflammatory, antioxidant, and neuroprotective properties in experimental cerebral malaria (ECM).

METHODS

ECM was induced in male C57BL/6 mice by infection with Plasmodium berghei ANKA (PbA). Ethanolic extracts of Atractylodes lancea (a dose of 400 mg/kg) and Prabchompoothaweep remedy (a dose of 600 mg/kg) were evaluated as monotherapy and adjunctive therapy combined with artesunate at the onset of signs of cerebral malaria and continued for 7 consecutive days. Parasitemia, clinical scores, and body weight were recorded throughout the study. At day 13 post-infection, mouse brains were dissected and processed for the study of the inflammatory response, oxidative stress, blood-brain barrier (BBB) integrity, histopathological changes, and neurocognitive impairments.

RESULTS

Ethanolic extracts of A. lancea and Prabchompoothaweep remedy alone improved cerebral malaria outcome in ECM, whereas artesunate combined with extracts of A. lancea or Prabchompoothaweep remedy significantly improved the outcome of artesunate and crude extracts alone. Using real-time PCR, PbA-infected mice that had received the combination treatment showed significantly reduced gene expression of inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-10), chemokines (CXCL4 and CXCL10), and adhesion molecules (ICAM-1, VCAM1, and CD36). The PbA-infected mice that received the combination treatment showed a significantly decreased malondialdehyde level compared to the untreated group. Similarly, the Evans blue dye assay revealed significantly less dye extravasation in the brains of infected mice administered the combination treatment, indicating improved BBB integrity. Combination treatment improved survival and reduced pathology in the PbA-infected group. Additionally, combination treatment resulted in a significantly reduced level of cognitive impairment, which was analyzed using a novel object recognition test.

CONCLUSIONS

This study demonstrated that artesunate combined with A. lancea or Prabchompoothaweep remedy extracts as adjunctive therapy reduced mortality, neuroinflammation, oxidative stress, BBB integrity protection, and neurocognitive impairment in the ECM.

Interplay Between the Immune and Nervous Cognitive Systems in Homeostasis and in Malaria

The immune and nervous systems can be thought of as cognitive and plastic systems, since they are both involved in cognition/recognition processes and can be architecturally and functionally modified by experience, and such changes can influence each other's functioning. The immune system can affect nervous system function depending on the nature of the immune stimuli and the pro/anti-inflammatory responses they generate. Here we consider interactions between the immune and nervous systems in homeostasis and disease, including the beneficial and deleterious effects of immune stimuli on brain function and the impact of severe and non-severe malaria parasite infections on neurocognitive and behavioral parameters in human and experimental murine malaria. We also discuss the effect of immunization on the reversal of cognitive deficits associated with experimental non-severe malaria in a model susceptible to the development of the cerebral form of the illness. Finally, we consider the possibility of using human vaccines, largely exploited as immune-prophylactics for infectious diseases, as therapeutic tools to prevent or mitigate the expression of cognitive deficits in infectious and chronic degenerative diseases.

Cerebrospinal fluid biomarkers provide evidence for kidney-brain axis involvement in cerebral malaria pathogenesis

Introduction

Cerebral malaria is one of the most severe manifestations of malaria and is a leading cause of acquired neurodisability in African children. Recent studies suggest acute kidney injury (AKI) is a risk factor for brain injury in cerebral malaria. The present study evaluates potential mechanisms of brain injury in cerebral malaria by evaluating changes in cerebrospinal fluid measures of brain injury with respect to severe malaria complications. Specifically, we attempt to delineate mechanisms of injury focusing on blood-brain-barrier integrity and acute metabolic changes that may underlie kidney-brain crosstalk in severe malaria.

Methods

We evaluated 30 cerebrospinal fluid (CSF) markers of inflammation, oxidative stress, and brain injury in 168 Ugandan children aged 18 months to 12 years hospitalized with cerebral malaria. Eligible children were infected with Plasmodium falciparum and had unexplained coma. Acute kidney injury (AKI) on admission was defined using the Kidney Disease: Improving Global Outcomes criteria. We further evaluated blood-brain-barrier integrity and malaria retinopathy, and electrolyte and metabolic complications in serum.

Results

The mean age of children was 3.8 years (SD, 1.9) and 40.5% were female. The prevalence of AKI was 46.3% and multi-organ dysfunction was common with 76.2% of children having at least one organ system affected in addition to coma. AKI and elevated blood urea nitrogen, but not other measures of disease severity (severe coma, seizures, jaundice, acidosis), were associated with increases in CSF markers of impaired blood-brain-barrier function, neuronal injury (neuron-specific enolase, tau), excitatory neurotransmission (kynurenine), as well as altered nitric oxide bioavailability and oxidative stress (p < 0.05 after adjustment for multiple testing). Further evaluation of potential mechanisms suggested that AKI may mediate or be associated with CSF changes through blood-brain-barrier disruption (p = 0.0014), ischemic injury seen by indirect ophthalmoscopy (p < 0.05), altered osmolality (p = 0.0006) and through alterations in the amino acids transported into the brain.

Conclusion

In children with cerebral malaria, there is evidence of kidney-brain injury with multiple potential pathways identified. These changes were specific to the kidney and not observed in the context of other clinical complications.

The kidney-brain pathogenic axis in severe falciparum malaria

Severe falciparum malaria is a medical emergency and a leading cause of death and neurodisability in endemic areas. Common complications include acute kidney injury (AKI) and cerebral malaria, and recent studies have suggested links between kidney and brain dysfunction in Plasmodium falciparum infection. Here, we review these new findings and present the hypothesis of a pivotal pathogenic crosstalk between the kidneys and the brain in severe falciparum malaria. We highlight the evidence of a role for distant organ involvement in the development of cerebral malaria and subsequent neurocognitive impairment post-recovery, describe the challenges associated with current diagnostic shortcomings for both AKI and brain involvement in severe falciparum malaria, and explore novel potential therapeutic strategies.

Diagnosis of cerebral malaria: Tools to reduce Plasmodium falciparum associated mortality

Cerebral malaria (CM) is a major cause of mortality in Plasmodium falciparum (Pf) infection and is associated with the sequestration of parasitised erythrocytes in the microvasculature of the host's vital organs. Prompt diagnosis and treatment are key to a positive outcome in CM. However, current diagnostic tools remain inadequate to assess the degree of brain dysfunction associated with CM before the window for effective treatment closes. Several host and parasite factor-based biomarkers have been suggested as rapid diagnostic tools with potential for early CM diagnosis, however, no specific biomarker signature has been validated. Here, we provide an updated review on promising CM biomarker candidates and evaluate their applicability as point-of-care tools in malaria-endemic areas.

Plasma Amino Acid Concentrations in Children With Severe Malaria Are Associated With Mortality and Worse Long-term Kidney and Cognitive Outcomes

BACKGROUND

Global changes in amino acid levels have been described in severe malaria (SM), but the relationship between amino acids and long-term outcomes in SM has not been evaluated.

METHODS

We measured enrollment plasma concentrations of 20 amino acids using high-performance liquid chromatography in 500 Ugandan children aged 18 months to 12 years, including 122 community children and 378 children with SM. The Kidney Disease: Improving Global Outcomes criteria were used to define acute kidney injury (AKI) at enrollment and chronic kidney disease (CKD) at 1-year follow-up. Cognition was assessed over 2 years of follow-up.

RESULTS

Compared to laboratory-defined, age-specific reference ranges, there were deficiencies in sulfur-containing amino acids (methionine, cysteine) in both community children and children with SM. Among children with SM, global changes in amino acid concentrations were observed in the context of metabolic complications including acidosis and AKI. Increases in threonine, leucine, and valine were associated with in-hospital mortality, while increases in methionine, tyrosine, lysine, and phenylalanine were associated with postdischarge mortality and CKD. Increases in glycine and asparagine were associated with worse attention in children <5 years of age.

CONCLUSIONS

Among children with SM, unique amino acid profiles are associated with mortality, CKD, and worse attention.

The Impact, Emerging Needs, and New Research Questions Arising from 12 Years of the Center for the Study of Complex Malaria in India

The Center for the Study of Complex Malaria in India (CSCMi) was launched in 2010 with the overall goal of addressing major gaps in our understanding of "complex malaria" in India through projects on the epidemiology, transmission, and pathogenesis of the disease. The Center was mandated to adopt an integrated approach to malaria research, including building capacity, developing infrastructure, and nurturing future malaria leaders while conducting relevant and impactful studies to assist India as it moves from control to elimination. Here, we will outline some of the interactions and impacts the Center has had with malaria policy and control counterparts in India, as well as describe emerging needs and new research questions that have become apparent over the past 12 years.

Elevated Plasma Soluble ST2 Levels are Associated With Neuronal Injury and Neurocognitive Impairment in Children With Cerebral Malaria

Background

Murine experimental cerebral malaria studies suggest both protective and deleterious central nervous system effects from alterations in the interleukin-33 (IL-33)/ST2 pathway.

Methods

We assessed whether soluble ST2 (sST2) was associated with neuronal injury or cognitive impairment in a cohort of Ugandan children with cerebral malaria (CM, n=224) or severe malarial anemia (SMA, n=193).

Results

Plasma concentrations of sST2 were higher in children with CM than in children with SMA or in asymptomatic community children. Cerebrospinal fluid (CSF) sST2 levels were elevated in children with CM compared with North American children. Elevated plasma and CSF ST2 levels in children with CM correlated with increased endothelial activation and increased plasma and CSF levels of tau, a marker of neuronal injury. In children with CM who were ≥5 years of age at the time of their malaria episode, but not in children <5 years of age, elevated risk factor-adjusted plasma levels of sST2 were associated with worse scores for overall cognitive ability and attention over a 2-year follow-up.

Conclusions

The study findings suggest that sST2 may contribute to neuronal injury and long-term neurocognitive impairment in older children with CM.

Acute kidney injury, persistent kidney disease, and post-discharge morbidity and mortality in severe malaria in children: A prospective cohort study

BACKGROUND

Globally, 85% of acute kidney injury (AKI) cases occur in low-and-middle-income countries. There is limited information on persistent kidney disease (acute kidney disease [AKD]) following severe malaria-associated AKI.

METHODS

Between March 28, 2014, and April 18, 2017, 598 children with severe malaria and 118 community children were enrolled in a two-site prospective cohort study in Uganda and followed up for 12 months. The Kidney Disease: Improving Global Outcomes (KDIGO) criteria were used to define AKI (primary exposure) and AKD at 1-month follow-up (primary outcome). Plasma neutrophil gelatinase-associated lipocalin (NGAL) was assessed as a structural biomarker of AKI.

FINDINGS

The prevalence of AKI was 45·3% with 21·5% of children having unresolved AKI at 24 h. AKI was more common in Eastern Uganda. In-hospital mortality increased across AKI stages from 1·8% in children without AKI to 26·5% with Stage 3 AKI (p < 0·0001). Children with a high-risk plasma NGAL test were more likely to have unresolved AKI (OR, 7·00 95% CI 4·16 to 11·76) and die in hospital (OR, 6·02 95% CI 2·83 to 12·81). AKD prevalence was 15·6% at 1-month follow-up with most AKD occurring in Eastern Uganda. Risk factors for AKD included severe/unresolved AKI, blackwater fever, and a high-risk NGAL test (adjusted p < 0·05). Paracetamol use during hospitalization was associated with reduced AKD (p < 0·0001). Survivors with AKD post-AKI had higher post-discharge mortality (17·5%) compared with children without AKD (3·7%).

INTERPRETATION

Children with severe malaria-associated AKI are at risk of AKD and post-discharge mortality.

FUNDING

This work was supported by the National Institutes of Health National Institute of Neurological Disorders and Stroke (R01NS055349 to CCJ) and the Fogarty International Center (D43 TW010928 to CCJ), and a Ralph W. and Grace M. Showalter Young Investigator Award to ALC.

Euterpe oleracea fruit (Açai)-enriched diet suppresses the development of experimental cerebral malaria induced by Plasmodium berghei (ANKA) infection

Background

Cerebral malaria is one of the most severe complications attributed to protozoal infection by Plasmodium falciparum, gaining prominence in children mortality rates in endemic areas. This condition has a complex pathogenesis associated with behavioral, cognitive and motor sequels in humans and current antimalarial therapies have shown little effect in those aspects. Natural products with antioxidant and anti-inflammatory properties have become a valuable alternative therapeutic option in the treatment of distinct conditions. In this context, this study investigated the neuroprotective effect of Euterpe oleracea (açai) enriched diet during the development of experimental cerebral malaria induced by the inoculation of Swiss albino mice with Plasmodium berghei ANKA strain.

Methods

After Plasmodium infection, animals were maintained on a feeding with Euterpe oleracea enriched ration and parameters such as survival curve, parasitemia and body weight were routinely monitored. The present study has also evaluated the effect of açai-enriched diet on the blood-brain barrier leakage, histological alterations and neurocognitive impairments in mice developing cerebral malaria.

Results

Our results demonstrate that between 7th–19th day post infection the survival rate of the group treated with açai enriched ration was higher when compared with Plasmodium-infected mice in which 100% of mice died until the 11th days post-infection, demonstrating that açai diet has a protective effect on the survival of infected treated animals. The same was observed in the brain vascular extravasation, where Evans blue dye assays showed significantly less dye extravasation in the brains of Plasmodium-infected mice treated with açai enriched ration, demonstrating more preserved blood-brain barrier integrity. Açai-enriched diet also attenuate the histopathological alterations elicited by Plasmodium berghei infection. We also showed a decrease of the neurological impairments arising from the exposure of cerebral parenchyma in the group treated with açai diet, ameliorating motor and neuropsychiatric changes, analyzed through the SHIRPA protocol.

Conclusion

With these results, we conclude that the treatment with açai enriched ration decreased the mortality of infected animals, as well as protected the blood-brain barrier and the neurocognitive deficits in Plasmodium-infected animals.

Association of Plasma Tau With Mortality and Long-term Neurocognitive Impairment in Survivors of Pediatric Cerebral Malaria and Severe Malarial Anemia

IMPORTANCE

Cerebral malaria (CM) and severe malarial anemia (SMA) are associated with persistent neurocognitive impairment (NCI) among children in Africa. Identifying blood biomarkers of acute brain injury that are associated with future NCI could allow early interventions to prevent or reduce NCI in survivors of severe malaria.

OBJECTIVE

To investigate whether acutely elevated tau levels are associated with future NCI in children after CM or SMA.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted at Mulago National Referral Hospital in Kampala, Uganda, from March 2008 to October 2015. Children aged 1.5 to 12 years with CM (n = 182) or SMA (n = 162) as well as community children (CC; n = 123) were enrolled in the study. Data analysis was conducted from January 2020 to May 2021.

EXPOSURE

CM or SMA.

MAIN OUTCOMES AND MEASURES

Enrollment plasma tau levels were measured using single-molecule array detection technology. Overall cognition (primary) and attention and memory (secondary) z scores were measured at 1 week and 6, 12, and 24 months after discharge using tools validated in Ugandan children younger than 5 years or 5 years and older.

RESULTS

A total of 467 children were enrolled. In the CM group, 75 (41%) were girls, and the mean (SD) age was 4.02 (1.92) years. In the SMA group, 59 (36%) were girls, and the mean (SD) age was 3.45 (1.60) years. In the CC group, 65 (53%) were girls, and the mean (SD) age was 3.94 (1.92) years. Elevated plasma tau levels (>95th percentile in CC group; >6.43 pg/mL) were observed in 100 children (55%) with CM and 69 children (43%) with SMA (P < .001). In children with CM who were younger than 5 years, elevated plasma tau levels were associated with increased mortality (odds ratio [OR], 3.06; 95% CI, 1.01-9.26; P = .048). In children with CM who were younger than 5 years at both CM episode and follow-up neurocognitive testing, plasma tau levels (log10 transformed) were associated with worse overall cognition scores over 24-month follow-up (β = -0.80; 95% CI, -1.32 to -0.27; P = .003). In children with CM who were younger than 5 years at CM episode and 5 years or older at follow-up neurocognitive testing, plasma tau was associated with worse scores in attention (β = -1.08; 95% CI, -1.79 to -0.38; P = .003) and working memory (β = -1.39; 95% CI, -2.18 to -0.60; P = .001).

CONCLUSIONS AND RELEVANCE

In this study, plasma tau, a marker of injury to neuronal axons, was elevated in children with CM or SMA and was associated with mortality and persistent NCI in children with CM younger than 5 years.

Mast cells-derived exosomes worsen the development of experimental cerebral malaria

Cerebral malaria (CM) is the most severe neurological complication caused by Plasmodium falciparum infection. The accumulating evidence demonstrated that mast cells (MCs) and its mediators played a critical role in mediating malaria severity. Earlier studies identified that exosomes were emerging as key mediators of intercellular communication and can be released from several kinds of MCs. However, the potential functions and pathological mechanisms of MCs-derived exosomes (MCs-Exo) impacting on CM pathogenesis remain largely unknown. Herein, we utilized an experimental CM (ECM) model (C57BL/6 mice infected with P. berghei ANKA strain), and then intravenously (i.v.) injected MCs-Exo into P. berghei ANKA-infected mice to unfold this mechanism and investigate the effect of MCs-Exo on ECM pathogenies. We also used an in vitro model by investigating the pathogenesis development of brain microvascular endothelial cells line (bEnd.3 cells) co-cultured with P. berghei ANKA blood-stage soluble antigen (PbAg) after MCs-Exo treatment. The higher numbers of MCs and levels of MCs degranulation were observed in skin, cervical lymph node, and brain of ECM mice than those of the uninfected mice. Exosomes were successfully isolated from culture supernatants of mouse MCs line (P815 cells) and characterized by spherical vesicles with the diameter of 30-150 nm, and expression of typical exosomal markers (e.g., CD9, CD63, and CD81). The i.v. injection of MCs-Exo dramatically elevated incidence of ECM in the P. berghei ANKA-infected mice, exacerbated liver and brain histopathological damage, promoted Th1 cytokine response, aggravated brain vascular endothelial activation and blood brain barrier breakdown in ECM mice. In addition, the treatment of MCs-Exo led to the decrease of cells viability and mRNA levels of Ang-1, ZO-1, and Claudin-5, but increase of mRNA levels of Ang-2, CCL2, CXCL1, and CXCL9 in bEnd.3 cells co-cultured with PbAg in vitro. Taken together, our data indicated that MCs-Exo could worsen pathogenesis of ECM in mice.

The Potential Roles of Glial Cells in the Neuropathogenesis of Cerebral Malaria

Cerebral malaria (CM) is a severe neurological complication of malaria caused by the Plasmodium falciparum parasite. It is one of the leading causes of death in children under 5 years of age in Sub-Saharan Africa. CM is associated with blood-brain barrier disruption and long-term neurological sequelae in survivors of CM. Despite the vast amount of research on cerebral malaria, the cause of neurological sequelae observed in CM patients is poorly understood. In this article, the potential roles of glial cells, astrocytes, and microglia, in cerebral malaria pathogenesis are reviewed. The possible mechanisms by which glial cells contribute to neurological damage in CM patients are also examined.

Role of cerebrospinal fluid tau protein levels as a biomarker of brain injury in pediatric status epilepticus

BACKGROUND

Various biomarkers have been studied for predicting etiology and outcome in status epilepticus (SE); cerebrospinal fluid (CSF) total tau (t-tau) protein levels is foremost among them. Only handful of studies are available regarding role of t-tau in childhood SE.

METHODOLOGY

This prospective study was conducted in a tertiary care center of Northern India in children 6 months -12 years of age. The Cases were patients with convulsive status epilepticus (CSE) whereas Controls were patients without SE and normal CSF. The t-tau levels were done in CSF of both the groups. The outcome was assessed by GOS-E Peds score.

RESULTS

A total of 50 (62% males) cases and 15 (67% males) controls were enrolled in the study. SE was generalized in 78% cases whereas 14% had refractory SE. Most common etiology of CSE was acute symptomatic (52%), followed by prolonged febrile seizure (24%), remote symptomatic group (14%), unknown etiology (8%) and progressive disorder (2%). Case fatality rate was 10%. Poor outcome was seen in 30% cases. Median (IQR) CSF t-tau levels was significantly lower 2.6 × 10³ (0.5-9.4 × 10³) pg/ml in cases vs 10.6 × 10³ (6.0-14.2 × 10³) pg/ml in controls (p = 0.004). There was no significant correlation seen between type, duration, etiology and response to antiepileptic drugs of SE with CSF t-tau levels. Also, no significant correlation of poor sensorium, outcome of SE and critical care needs with CSF t-tau levels was noted.

CONCLUSION

CSF t-tau is not a useful diagnostic or prognostic biomarker in pediatric SE.

Malaria-Associated Acute Kidney Injury in African Children: Prevalence, Pathophysiology, Impact, and Management Challenges

Acute kidney injury (AKI) is emerging as a complication of increasing clinical importance associated with substantial morbidity and mortality in African children with severe malaria. Using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria to define AKI, an estimated 24–59% of African children with severe malaria have AKI with most AKI community-acquired. AKI is a risk factor for mortality in pediatric severe malaria with a stepwise increase in mortality across AKI stages. AKI is also a risk factor for post-discharge mortality and is associated with increased long-term risk of neurocognitive impairment and behavioral problems in survivors. Following injury, the kidney undergoes a process of recovery and repair. AKI is an established risk factor for chronic kidney disease and hypertension in survivors and is associated with an increased risk of chronic kidney disease in severe malaria survivors. The magnitude of the risk and contribution of malaria-associated AKI to chronic kidney disease in malaria-endemic areas remains undetermined. Pathways associated with AKI pathogenesis in the context of pediatric severe malaria are not well understood, but there is emerging evidence that immune activation, endothelial dysfunction, and hemolysis-mediated oxidative stress all directly contribute to kidney injury. In this review, we outline the KDIGO bundle of care and highlight how this could be applied in the context of severe malaria to improve kidney perfusion, reduce AKI progression, and improve survival. With increased recognition that AKI in severe malaria is associated with substantial post-discharge morbidity and long-term risk of chronic kidney disease, there is a need to increase AKI recognition through enhanced access to creatinine-based and next-generation biomarker diagnostics. Long-term studies to assess severe malaria-associated AKI’s impact on long-term health in malaria-endemic areas are urgently needed.

Endothelial Activation, Acute Kidney Injury, and Cognitive Impairment in Pediatric Severe Malaria

OBJECTIVES

Evaluate the relationship between endothelial activation, malaria complications, and long-term cognitive outcomes in severe malaria survivors.

DESIGN

Prospectively cohort study of children with cerebral malaria, severe malarial anemia, or community children.

SETTING

Mulago National Referral Hospital in Kampala, Uganda.

SUBJECTS

Children 18 months to 12 years old with severe malaria (cerebral malaria, n = 253 or severe malarial anemia, n = 211) or community children (n = 206) were followed for 24 months.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Children underwent neurocognitive evaluation at enrollment (community children) or a week following hospital discharge (severe malaria) and 6, 12, and 24 months follow-up. Endothelial activation was assessed at admission on plasma samples (von Willebrand factor, angiopoietin-1 and angiopoietin-2, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, soluble E-Selectin, and P-Selectin). False discovery rate was used to adjust for multiple comparisons. Severe malaria was associated with widespread endothelial activation compared with community children (p < 0.0001 for all markers). Acute kidney injury was independently associated with changes in von Willebrand factor, soluble intercellular adhesion molecule-1, soluble E-Selectin, P-Selectin, and angiopoietin-2 (p < 0.0001 for all). A log10 increase in angiopoietin-2 was associated with lower cognitive z scores across age groups (children < 5, β -0.42, 95% CI, -0.69 to -0.15, p = 0.002; children ≥ 5, β -0.39, 95% CI, -0.67 to -0.11, p = 0.007) independent of disease severity (coma, number of seizures, acute kidney injury) and sociodemographic factors. Angiopoietin-2 was associated with hemolysis (lactate dehydrogenase, total bilirubin) and inflammation (tumor necrosis factor-α, interleukin-10). In children with cerebral malaria who had a lumbar puncture performed, angiopoietin-2 was associated with blood-brain barrier dysfunction, and markers of neuroinflammation and injury in the cerebrospinal fluid (tumor necrosis factor-α, kynurenic acid, tau).

CONCLUSIONS

These data support angiopoietin-2 as a measure of disease severity and a risk factor for long-term cognitive injury in children with severe malaria.

Neurocognitive function among HIV-infected children on protease inhibitor -based versus non-protease inhibitor based antiretroviral therapy in Uganda: a pilot study

BACKGROUND

HIV infection is associated with significant neurocognitive deficits making maximization of cognitive function among children receiving antiretroviral therapy (ART) a public health imperative. Non-protease inhibitors (non-PIs) achieve higher drug levels in the cerebral spinal fluid (CSF) compared to PIs, potentially leading to better neurocognitive function by reducing CSF viral load and inflammation. ART that maximises children's neurodevelopment and school achievement could result in improved quality of life and productivity as adults, but little research to date has examined whether non-PI ART is associated with better neurocognitive outcomes. We compared the neurocognitive function between children living with HIV receiving PI-based and non PI-based ART.

METHODS

We recruited a consecutive sample of clinically stable Ugandan children living with HIV aged 5-12 years who received PI-based or non PI-based ART for ≥ 1 year (viral load < 1000 copies). Neurocognitive function was assessed using the Kaufman Assessment Battery for Children, the Test of Variables of Attention, and Bruininks-Oseretsky Test of Motor Proficiency. Age-adjusted neurocognitive z-scores for the two groups were compared using linear regression models in STATA version 13. The Hommel's method was used to adjust for multiple testing.

RESULTS

We enrolled 76 children living with HIV; 34 on PI ART and 42 on non-PI ART. Mean (±SD) age was greater in the non-PI vs. PI group (9.5 ± 1.9 vs. 8.5 ± 2.0) years (p = 0.03). Children in the non-PI group had lower socioeconomic scores (5.7 ± 3.3 vs. 7.4 ± 2.8, p = 0.02). There was no difference in neurocognitive function between the groups (adjusted p > 0.05) for KABC and TOVA. Children in the PI group had better total BOT scores than their counterparts (46.07 ± 1.40) vs. 40.51 (1.24), p = 0.03).

CONCLUSIONS

We detected no difference in neurocognitive function among children on PI and non PI-based ART therapy based on KABC and TOVA tests. Children on PI based ART had better motor function than their counterparts. We recommend a prospective study with a larger sample size.

Plasma angiopoietin-2 is associated with age-related deficits in cognitive sub-scales in Ugandan children following severe malaria

Background

Elevated angiopoietin-2 (Angpt-2) concentrations are associated with worse overall neurocognitive function in severe malaria survivors, but the specific domains affected have not been elucidated.

Methods

Ugandan children with severe malaria underwent neurocognitive evaluation a week after hospital discharge and at 6, 12 and 24 months follow-up. The relationship between Angpt-2 concentrations and age-adjusted, cognitive sub-scale z-scores over time were evaluated using linear mixed effects models, adjusting for disease severity (coma, acute kidney injury, number of seizures in hospital) and sociodemographic factors (age, gender, height-for-age z-score, socio-economic status, enrichment in the home environment, parental education, and any preschool education of the child). The Mullen Scales of Early Learning was used in children < 5 years and the Kaufman Assessment Battery for Children 2nd edition was used in children ≥ 5 years of age. Angpt-2 levels were measured on admission plasma samples by enzyme-linked immunosorbent assay. Adjustment for multiple comparisons was conducted using the Benjamini–Hochberg Procedure of False Discovery Rate.

Results

Increased admission Angpt-2 concentration was associated with worse outcomes in all domains (fine and gross motor, visual reception, receptive and expressive language) in children < 5 years of age at the time of severe malaria episode, and worse simultaneous processing and learning in children < 5 years of age at the time of severe malaria who were tested when ≥ 5 years of age. No association was seen between Angpt-2 levels and cognitive outcomes in children ≥ 5 years at the time of severe malaria episode, but numbers of children and testing time points were lower for children ≥ 5 years at the time of severe malaria episode.

Conclusion

Elevated Angpt-2 concentration in children with severe malaria is associated with worse outcomes in multiple neurocognitive domains. The relationship between Angpt-2 and worse cognition is evident in children < 5 years of age at the time of severe malaria presentation and in selected domains in older years.

Blood Biomarkers for Detection of Brain Injury in COVID-19 Patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus attacks multiple organs of coronavirus disease 2019 (COVID-19) patients, including the brain. There are worldwide descriptions of neurological deficits in COVID-19 patients. Central nervous system (CNS) symptoms can be present early in the course of the disease. As many as 55% of hospitalized COVID-19 patients have been reported to have neurological disturbances three months after infection by SARS-CoV-2. The mutability of the SARS-COV-2 virus and its potential to directly affect the CNS highlight the urgency of developing technology to diagnose, manage, and treat brain injury in COVID-19 patients. The pathobiology of CNS infection by SARS-CoV-2 and the associated neurological sequelae of this infection remain poorly understood. In this review, we outline the rationale for the use of blood biomarkers (BBs) for diagnosis of brain injury in COVID-19 patients, the research needed to incorporate their use into clinical practice, and the improvements in patient management and outcomes that can result. BBs of brain injury could potentially provide tools for detection of brain injury in COVID-19 patients. Elevations of BBs have been reported in cerebrospinal fluid (CSF) and blood of COVID-19 patients. BB proteins have been analyzed in CSF to detect CNS involvement in patients with infectious diseases, including human immunodeficiency virus and tuberculous meningitis. BBs are approved by the U.S. Food and Drug Administration for diagnosis of mild versus moderate traumatic brain injury and have identified brain injury after stroke, cardiac arrest, hypoxia, and epilepsy. BBs, integrated with other diagnostic tools, could enhance understanding of viral mechanisms of brain injury, predict severity of neurological deficits, guide triage of patients and assignment to appropriate medical pathways, and assess efficacy of therapeutic interventions in COVID-19 patients.

Predictors of outcome in childhood Plasmodium falciparum malaria

Plasmodium falciparum malaria is classified as either uncomplicated or severe, determining clinical management and providing a framework for understanding pathogenesis. Severe malaria in children is defined by the presence of one or more features associated with adverse outcome, but there is wide variation in the predictive value of these features. Here we review the evidence for the usefulness of these features, alone and in combination, to predict death and other adverse outcomes, and we consider the role that molecular biomarkers may play in augmenting this prediction. We also examine whether a more personalized approach to predicting outcome for specific presenting syndromes of severe malaria, particularly cerebral malaria, has the potential to be more accurate. We note a general need for better external validation in studies of outcome predictors and for the demonstration that predictors can be used to guide clinical management in a way that improves survival and long-term health.

Serum levels of total human Tau associated with axonal damage among severe malaria patients in Central India

Tau is a microtubule-associated protein (MAP) that is abundant in the axonal part of neurons of the central nervous system. Previous studies among African children and Vietnamese adults suffering from cerebral malaria (CM) showed the pathological significance of measuring circulatory total Tau levels. A pilot investigation was carried out to better characterise neurological pathogenesis among severe malaria patients in Central India. Serum levels of total human Tau (pg/ml) were measured by ELISA following manufacturer guidelines among hospital admitted P. falciparum malaria patients classified with different degree of severity (mild malaria = MM, non-cerebral severe malaria = NCSM, cerebral malaria survivors = CM-S and cerebral malaria non-survivors = CM-NS) using WHO, 2000 definitions, including healthy controls (HC) enroled from the hospital's blood bank. Categorical and numerical variables were analysed by applying appropriate statistical test using Stata 11.0 software. A total of 139 subjects (14 HC, 25 MM, 29 NCSM, 44 CM-S and 27 CM-NS) were included in this preliminary investigation. Serum levels of total human Tau were detected in 0% HC, 4.0% MM, 20.7% NCSM, 43.2% CM-S and 48.2% CM-NS patients. Compared to MM, percent Tau detection was significantly higher among severe malaria patients (p = 0.001). Further, compared to NCSM,% Tau detection was significantly higher in CM-S patients (Chi² = 3.9, p = 0.048) & CM-NS patients (Chi² = 4.7, p = 0.030). Percent Tau detection was also significantly higher among severe malaria cases presenting with multiple complications compared to those without multiple complications (p = 0.006). ROC analysis of serum Tau levels (pg/ml) revealed a fair AUC value (0.75) to distinguish CM-NS group (but not CM-S) from NCSM group. In conclusion, serum percent detection of total human Tau is associated with axonal damage among patients with different degree of P. falciparum malaria severity in Central India.