Cerebral malaria: mechanisms of brain injury and strategies for improved neurocognitive outcome

A morphological and molecular approach to investigating infectious disease in early medieval Iberia: The necropolis of La Olmeda (Palencia, Spain)

OBJECTIVE

Here we investigate infectious diseases that potentially contribute to osteological lesions in individuals from the early medieval necropolis of La Olmeda (6th-11th c. CE) in North Iberia.

MATERIALS AND METHODS

We studied a minimum number of 268 individuals (33 adult females; 38 adult males, 77 unknown/indeterminate sex; and 120 non-adults), including articulated and commingled remains. Individuals with differential diagnoses suggesting chronic systemic infectious diseases were sampled and bioinformatically screened for ancient pathogen DNA.

RESULTS

Five non-adults (and no adults) presented skeletal evidence of chronic systemic infectious disease (1.87% of the population; 4.67% of non-adults). The preferred diagnoses for these individuals included tuberculosis, brucellosis, and malaria. Ancient DNA fragments assigned to the malaria-causing pathogen, Plasmodium spp., were identified in three of the five individuals. Observed pathology includes lesions generally consistent with malaria; however, additional lesions in two of the individuals may represent hitherto unknown variation in the skeletal manifestation of this disease or co-infection with tuberculosis or brucellosis. Additionally, spondylolysis was observed in one individual with skeletal lesions suggestive of infectious disease.

CONCLUSIONS

This study sheds light on the pathological landscape in Iberia during a time of great social, demographic, and environmental change. Genetic evidence challenges the hypothesis that malaria was absent from early medieval Iberia and demonstrates the value of combining osteological and archaeogenetic methods. Additionally, all of the preferred infectious diagnoses for the individuals included in this study (malaria, tuberculosis, and brucellosis) could have contributed to the febrile cases described in historical sources from this time.

Understanding the pathogenic mechanisms and therapeutic effects in neurocysticercosis

Despite being a leading cause of acquired seizures in endemic regions, the pathological mechanisms of neurocysticercosis are still poorly understood. This study aims to investigate the impact of anthelmintic treatment on neuropathological features in a rat model of neurocysticercosis. Rats were intracranially infected with Taenia solium oncospheres and treated with albendazole + praziquantel (ABZ), oxfendazole + praziquantel (OXF), or untreated placebo (UT) for 7 days. Following the last dose of treatment, brain tissues were evaluated at 24 h and 2 months. We performed neuropathological assessment for cyst damage, perilesional brain inflammation, presence of axonal spheroids, and spongy changes. Both treatments showed comparable efficacy in cyst damage and inflammation. The presence of spongy change correlated with spheroids counts and were not affected by anthelmintic treatment. Compared to white matter, gray matter showed greater spongy change (91.7% vs. 21.4%, p < 0.0001), higher spheroids count (45.2 vs. 0.2, p = 0.0001), and increased inflammation (72.0% vs. 21.4%, p = 0.003). In this rat model, anthelmintic treatment destroyed brain parasitic cysts at the cost of local inflammation similar to what is described in human neurocysticercosis. Axonal spheroids and spongy changes as markers of damage were topographically correlated, and not affected by anthelmintic treatment.

The mRNA content of plasma extracellular vesicles provides a window into molecular processes in the brain during cerebral malaria

The impact of cerebral malaria on the transcriptional profiles of cerebral tissues is difficult to study using noninvasive approaches. We isolated plasma extracellular vesicles (EVs) from patients with cerebral malaria and community controls and sequenced their mRNA content. Deconvolution analysis revealed that EVs from cerebral malaria are enriched in transcripts of brain origin. We ordered the patients with cerebral malaria based on their EV-transcriptional profiles from cross-sectionally collected samples and inferred disease trajectory while using healthy community controls as a starting point. We found that neuronal transcripts in plasma EVs decreased with disease trajectory, whereas transcripts from glial, endothelial, and immune cells increased. Disease trajectory correlated positively with severity indicators like death and was associated with increased VEGFA-VEGFR and glutamatergic signaling, as well as platelet and neutrophil activation. These data suggest that brain tissue responses in cerebral malaria can be studied noninvasively using EVs circulating in peripheral blood.

Potential of extracellular vesicles in the pathogenesis, diagnosis and therapy for parasitic diseases

Parasitic diseases have a significant impact on human and animal health, representing a major hazard to the public and causing economic and health damage worldwide. Extracellular vesicles (EVs) have long been recognized as diagnostic and therapeutic tools but are now also known to be implicated in the natural history of parasitic diseases and host immune response modulation. Studies have shown that EVs play a role in parasitic disease development by interacting with parasites and communicating with other types of cells. This review highlights the most recent research on EVs and their role in several aspects of parasite-host interactions in five key parasitic diseases: Chagas disease, malaria, toxoplasmosis, leishmaniasis and helminthiases. We also discuss the potential use of EVs as diagnostic tools or treatment options for these infectious diseases.

Anesthetic approach to pregnant patients with malaria: a narrative review of the literature

INTRODUCTION

Anesthesiologists play an important role in the management of labor and delivery during acute malaria infection. The peripartum anesthesia considerations for such cases remain unclear.

FINDINGS

Important peripartum considerations include the severity of thrombocytopenia and coagulopathy, hemodynamic status and cardiac disease, and the likelihood of central nervous system (CNS) involvement. Several antimalarial drugs may interact with perioperative medications, causing hypoglycemia, methemoglobinemia, or QT prolongation. Labor should usually not be induced. Patient volume status should be optimized pre-induction, but fluids should be administered with caution given the risk of cerebral edema. In case of CNS involvement intracranial pressure should be maintained. Case reports describe the successful use of neuraxial anesthesia but this approach requires further confirmation of safety. Despite the risks accompanying airway management in pregnancy, in some cases, general anesthesia was preferred due to the chance of CNS infection and disease complications. Tight postoperative assessments of neurological and bleeding status are indicated regardless of the mode of delivery.

CONCLUSIONS

Despite the prevalence of malaria, the perioperative risk and preferred mode of anesthesia for pregnant patients with acute malaria remain under-researched and outcome data are limited.

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.

Severe malaria-related disability in Ethiopian children from the perspectives of caregivers: an interpretive description study

PURPOSE

This study explored severe malaria-related disability in children from the perspectives of their caregivers.

MATERIALS AND METHODS

The interpretive description qualitative approach was employed. The participants were selected using the purposive sampling technique considering the child's history of severe malaria, age (0-10 years), and location (urban/rural). Data were collected through face-to-face interviews with sixteen caregivers. Reflexive thematic data analysis was utilized. Through prolonged engagement, reflective journaling, an audit trail, and co-authors' review, trustworthiness was enhanced.

RESULTS

The study generated five themes from the interviews: mitigators of disability, contributors of disability, impact on body function, impact on activities and participation, and uncertainties about future well-being. The findings revealed previously unstudied social components of disability and environmental factors. Furthermore, the research uncovered health-related quality of life aspects that are out of the scope of the current comprehensive disability framework.

CONCLUSIONS

The study contributes to a deeper understanding of severe malaria-related disability in children from the biopsychosocial perspective. The findings could help policymakers, researchers, and clinicians who want to design rehabilitation interventions for the affected children or examine the components of disability on a large scale using quantitative methods.IMPLICATIONS FOR REHABILITATIONVarious contextual factors interacted with severe malaria and influenced functioning either as facilitators or barriers, implying disability related to malaria can be prevented or created.The long-term impacts of severe malaria are not limited to functioning and disability but also affect the health-related quality of life of children who survive severe malaria.Rehabilitation professionals should consider applying comprehensive functioning and disability frameworks such as the ICF when designing (or applying) screening tools, planning interventions, and evaluating the outcomes of intervention for children with severe malaria-related disability.Rehabilitation interventions for children with severe malaria-related disability should consider patient- or caregiver-reported outcomes (components of disability).

Cerebral malaria pathogenesis: Dissecting the role of CD4+ and CD8+ T-cells as major effectors in disease pathology

Cerebral malaria (CM) is a severe complication of Plasmodium falciparum (P. falciparum) infection, with complex pathogenesis involving multiple factors, including the host's immunological response. T lymphocytes, specifically CD4+ T helper cells and CD8+ cytotoxic T cells, are crucial in controlling parasite growth and activating cells for parasite clearance via cytokine secretion. Contrary to this, reports also suggest the pathogenic nature of T lymphocytes as they are often involved in disease progression and severity. CD8+ cytotoxic T cells migrate to the host's brain vasculature, disrupting the blood-brain barrier and causing neurological manifestations. CD4+ T helper cells on the other hand play a variety of functions as they differentiate into different subtypes which may function as pro-inflammatory or anti-inflammatory. The excessive pro-inflammatory response in CM can lead to multi-organ failure, necessitating a check mechanism to maintain immune homeostasis. This is achieved by regulatory T cells and their characteristic cytokines, which counterbalance the pro-inflammatory immune response. Maintaining a critical balance between pro and anti-inflammatory responses is crucial for determining disease outcomes in CM. A slight change in this balance may contribute to a disease severity owing to an extreme inflammatory response or unrestricted parasite growth, a potential target for designing immunotherapeutic treatment approaches. The review briefly discusses the pathogenesis of CM and various mechanisms responsible for the disruption of the blood-brain barrier. It also highlights the role of different T cell subsets during infection and emphasizes the importance of balance between pro and anti-inflammatory T cells that ultimately decides the outcome of the disease.

Rapid diagnosis and prognosis of malaria infection using a microfluidic point-of-care immunoassay

Malaria is a major cause of illness and death worldwide. Rapid diagnostic tests are the most widely used tool for detecting malaria infection, however, they only provide binary results and lack the sensitivity needed to detect many asymptomatic infections. Molecular assays for quantifying malaria biomarkers offer higher detection sensitivity, however, they are time-consuming, and require expert training and expensive equipment, making them unsuitable for use in most of Africa. To address the need for simple, accurate and field-deployable malaria diagnostic tests, we have developed a microfluidic point-of-care (mPOC) immunoassay for rapid quantification of Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a malaria parasite biomarker, in whole blood. This device features two diagnostic modes for detecting PfHRP2 at low (100's pg/mL) and high (1,000's ng/mL) concentrations, making it useful for multiple diagnostic applications, including the detection of asymptomatic infection, prediction of disease outcomes and diagnosis of cerebral malaria. Measurements of PfHRP2 in blood samples from malaria patients demonstrates that this platform offers similar accuracy as an ultra-sensitive PfHRP2 enzyme-linked immunosorbent assay (ELISA) test, while being 12× faster and simpler to use. This mPOC immunoassay can be deployed in rural health centers to assist clinicians in diagnosing and triaging malaria patients, ultimately improving patient outcomes.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses

Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.

Optic nerve sheath diameter and its association with brain swelling in pediatric cerebral malaria: a retrospective study

Introduction

Mortality in pediatric cerebral malaria (CM) in low- and middle-income countries (LMICs) is associated with brain swelling on magnetic resonance imaging (MRI); however, MRI is unavailable in most LMICs. Optic nerve sheath diameter (ONSD) measurement is an inexpensive method of detecting increased intracranial pressure compared with the invasive opening pressure (OP). Our primary objective was to determine if increased ONSD correlated with brain swelling on MRI in pediatric CM. Our secondary objective was to determine if increased ONSD correlated with increased OP and/or poor neurological outcome in pediatric CM. We hypothesized that increased ONSD would correlate with brain swelling on MRI and increased OP and that ONSD would be higher in survivors with sequelae and non-survivors.

Methods

We performed a retrospective chart review of children aged 0-12 years in Blantyre, Malawi, from 2013 to 2022 with CM as defined by the World Health Organization. Brain swelling on admission MRI was characterized by brain volume scores (BVS); severe swelling was scored as 7-8, mild-to-moderate as 4-6, normal as 3. The admission ONSD was measured via ultrasound; it was defined as abnormal if it was >4.5 mm in children >1 year and >4 mm in children <1 year. Favorable outcome was defined as a normal neurological exam on discharge in survivors. The primary and secondary objectives were evaluated using Spearman's correlation; and the demographics were compared using chi-square and the Kruskal-Wallis test (Stata, College Station, TX, USA).

Results

Median age of the 207-patients cohort was 50 months [interquartile range (IQR) 35-75]; 49% (n = 102) were female. Of those, 73% (n = 152) had a favorable outcome, and 14% (n = 30) died. Twenty-nine (14%) had a normal BVS, 134 (65%) had mild-to-moderate swelling, and 44 (21%) had severe swelling. ONSD was elevated in 86% (n = 178) of patients, while 12% of patients had increased OP. There was a weakly positive correlation between BVS and ONSD (r = 0.14, p = 0.05). The median ONSD was not significantly different compared by discharge outcome (p = 0.11) or by BVS (p = 0.18).

Conclusion

ONSD was not a reliable tool to correlate with BVS, neurological outcome, or OP in children with CM. Future studies to identify alternative methods of early identification of CM patients at highest risk for morbidity and mortality are urgently needed.

Exploring adjunctive therapies for cerebral malaria

Cerebral malaria (CM) is one of the most severe complications of malaria infection characterized by coma and neurological effects. Despite standardized treatment of malaria infection with artemisinin-based combination therapies (ACT), the mortality rate is still high, and it primarily affects pediatric patients. ACT reduces parasitemia but fails to adequately target the pathogenic mechanisms underlying CM, including blood-brain-barrier (BBB) disruption, endothelial activation/dysfunction, and hyperinflammation. The need for adjunctive therapies to specifically treat this form of severe malaria is critical as hundreds of thousands of people continue to die each year from this disease. Here we present a summary of some potential promising therapeutic targets and treatments for CM, as well as some that have been tested and deemed ineffective or, in some cases, even deleterious. Further exploration into these therapeutic agents is warranted to assess the effectiveness of these potential treatments for CM patients.

Discrete class I molecules on brain endothelium differentially regulate neuropathology in experimental cerebral malaria

Cerebral malaria is the deadliest complication that can arise from Plasmodium infection. CD8 T-cell engagement of brain vasculature is a putative mechanism of neuropathology in cerebral malaria. To define contributions of brain endothelial cell major histocompatibility complex (MHC) class I antigen-presentation to CD8 T cells in establishing cerebral malaria pathology, we developed novel H-2Kb LoxP and H-2Db LoxP mice crossed with Cdh5-Cre mice to achieve targeted deletion of discrete class I molecules, specifically from brain endothelium. This strategy allowed us to avoid off-target effects on iron homeostasis and class I-like molecules, which are known to perturb Plasmodium infection. This is the first endothelial-specific ablation of individual class-I molecules enabling us to interrogate these molecular interactions. In these studies, we interrogated human and mouse transcriptomics data to compare antigen presentation capacity during cerebral malaria. Using the Plasmodium berghei ANKA model of experimental cerebral malaria (ECM), we observed that H-2Kb and H-2Db class I molecules regulate distinct patterns of disease onset, CD8 T-cell infiltration, targeted cell death and regional blood-brain barrier disruption. Strikingly, ablation of either molecule from brain endothelial cells resulted in reduced CD8 T-cell activation, attenuated T-cell interaction with brain vasculature, lessened targeted cell death, preserved blood-brain barrier integrity and prevention of ECM and the death of the animal. We were able to show that these events were brain-specific through the use of parabiosis and created the novel technique of dual small animal MRI to simultaneously scan conjoined parabionts during infection. These data demonstrate that interactions of CD8 T cells with discrete MHC class I molecules on brain endothelium differentially regulate development of ECM neuropathology. Therefore, targeting MHC class I interactions therapeutically may hold potential for treatment of cases of severe malaria.

Updated Anopheles mosquitos abundance and distribution in north-eastern malaria-free area of Argentina

Malaria is the most important parasitic disease worldwide. In 2019, more than 679,441 cases of malaria were reported in the American region. During this study, Argentina was in malaria pre-elimination autochthonous transmission phase with the aim of being declared as malaria-free country. The aim of this work was to assess the influence of remote sensing spectral indices (NDVI, NDWI) and climatic variables (temperature, relative humidity and precipitation) on the distribution and abundance of Anopheles mosquitoes, in four localities with different degrees of anthropogenic disturbance and with previous malaria cases records located , in a historical malarious area in northeastern of Argentina. Between June 2012 and July 2014, mosquitoes were collected. We collected 535 Anopheles adult mosquitoes. Anopheles strodei s.l. was the most abundant species. The greatest richness, diversity and abundance of species were registered in wild and semi-urban environments. The abundance of Anopheles presented a negative association with relative humidity and mean temperature, but positive with mean maximum temperature. The most important variables determining Anopheles total abundance and distribution were NDWI Index and distance to vegetation. The abundance of An. strodei s.l., was positive associated with water areas whereas the NDVI Index was negatively associated.

Bradykinin produced during Plasmodium falciparum erythrocytic cycle drives monocyte adhesion to human brain microvascular endothelial cells

Cerebral malaria (CM) pathogenesis is described as a multistep mechanism. In this context, monocytes have been implicated in CM pathogenesis by increasing the sequestration of infected red blood cells to the brain microvasculature. In disease, endothelial activation is followed by reduced monocyte rolling and increased adhesion. Nowadays, an important challenge is to identify potential pro-inflammatory stimuli that can modulate monocytes behavior. Our group have demonstrated that bradykinin (BK), a pro-inflammatory peptide involved in CM, is generated during the erythrocytic cycle of P. falciparum and is detected in culture supernatant (conditioned medium). Herein we investigated the role of BK in the adhesion of monocytes to endothelial cells of blood brain barrier (BBB). To address this issue human monocytic cell line (THP-1) and human brain microvascular endothelial cells (hBMECs) were used. It was observed that 20% conditioned medium from P. falciparum infected erythrocytes (Pf-iRBC sup) increased the adhesion of THP-1 cells to hBMECs. This effect was mediated by BK through the activation of B2 and B1 receptors and involves the increase in ICAM-1 expression in THP-1 cells. Additionally, it was observed that angiotensin-converting enzyme (ACE) inhibitor, captopril, enhanced the effect of both BK and Pf-iRBC sup on THP-1 adhesion. Together these data show that BK, generated during the erythrocytic cycle of P. falciparum, could play an important role in adhesion of monocytes in endothelial cells lining the BBB.

Pattern of Clinical and Laboratory Presentation of Cerebral Malaria among Children in Nigeria

Introduction

Cerebral malaria (CM) is the most lethal form of severe malaria with high case fatality rates. Overtime, there is an inherent risk in changing pattern of presentation of CM which, if the diagnosis is missed due to these changing factors, may portend a poor outcome. Variations in the pattern of clinic-laboratory presentations also make generalization difficult. This study was, therefore, set out to report the pattern of clinical and laboratory presentation of CM.

Methods

This was a cross-sectional study among children aged 6 months to 14 years admitted with a diagnosis of CM as defined by the World Health Organization criteria. A pretested pro forma was filled, and detailed neurological examination and laboratory (biochemical, microbiology, and hematology) investigations were done. P <5% was considered statistically significant.

Results

Sixty-four children were recruited with a mean age of 34.9 ± 24.9 months and a male-to-female ratio of 1.9:1. There were 87.5% of under-five children. Fever (96.9%) was the major presenting feature closely followed by convulsions (92.2%). Convulsions were mainly generalized (94.9%) and multiple (76.5%). Profound coma (Blantyre coma score of 0) was present in 12.5% of cases, and the leading features on examination were fever (84.4%) and pallor (75.0%). Retinal vessel whitening (48.4%) was the most common funduscopic abnormality. Metabolic acidosis (47.9%), severe anemia (14.1%), hyperglycemia (17.2%), and hypoglycemia (7.8%) were seen among the children. Few (1.6%) had hyperparasitemia and bacteremia (3.2%).

Conclusion

Early recognition of the clinical presentation and prompt management may improve the outcome of cerebral malaria.

PARACENTRAL ACUTE MIDDLE MACULOPATHY ASSOCIATED WITH SEVERE PLASMODIUM FALCIPARUM MALARIA

PURPOSE

To report a case of bilateral paracentral acute middle maculopathy lesions on spectral domain-optical coherence tomography(OCT) secondary to severe Plasmodium falciparum malaria.

METHODS

Retrospective case report. Spectral domain-OCT, ultra-widefield fluorescein angiography, and OCT angiography were performed and analyzed.

RESULTS

A 54-year-old healthy man presented with acute vision loss in both eyes few days after being diagnosed with severe Plasmodium falciparum malaria. Ophthalmoscopic examination was unremarkable, but near-infrared reflectance imaging showed patchy hyporeflective areas located at the terminal tips of the venous branches. Corresponding spectral-domain OCT demonstrated alternating bands of hyperreflectivity involving the inner nuclear layer, consistent with skip paracentral acute middle maculopathy lesions. Optical coherance tomography angiography illustrated corresponding flow signal loss at the level of the deep capillary plexus. Ultra-widefield fluorescein angiography showed peripheral retinal vein staining and capillary nonperfusion.

CONCLUSION

Paracentral acute middle maculopathy may be an OCT manifestation of malarial retinopathy associated with severe Plasmodium falciparum infection.

TNFR1 signaling converging on FGF14 controls neuronal hyperactivity and sickness behavior in experimental cerebral malaria

BACKGROUND

Excess tumor necrosis factor (TNF) is implicated in the pathogenesis of hyperinflammatory experimental cerebral malaria (eCM), including gliosis, increased levels of fibrin(ogen) in the brain, behavioral changes, and mortality. However, the role of TNF in eCM within the brain parenchyma, particularly directly on neurons, remains underdefined. Here, we investigate electrophysiological consequences of eCM on neuronal excitability and cell signaling mechanisms that contribute to observed phenotypes.

METHODS

The split-luciferase complementation assay (LCA) was used to investigate cell signaling mechanisms downstream of tumor necrosis factor receptor 1 (TNFR1) that could contribute to changes in neuronal excitability in eCM. Whole-cell patch-clamp electrophysiology was performed in brain slices from eCM mice to elucidate consequences of infection on CA1 pyramidal neuron excitability and cell signaling mechanisms that contribute to observed phenotypes. Involvement of identified signaling molecules in mediating behavioral changes and sickness behavior observed in eCM were investigated in vivo using genetic silencing.

RESULTS

Exploring signaling mechanisms that underlie TNF-induced effects on neuronal excitability, we found that the complex assembly of fibroblast growth factor 14 (FGF14) and the voltage-gated Na+ (Nav) channel 1.6 (Nav1.6) is increased upon tumor necrosis factor receptor 1 (TNFR1) stimulation via Janus Kinase 2 (JAK2). On account of the dependency of hyperinflammatory experimental cerebral malaria (eCM) on TNF, we performed patch-clamp studies in slices from eCM mice and showed that Plasmodium chabaudi infection augments Nav1.6 channel conductance of CA1 pyramidal neurons through the TNFR1-JAK2-FGF14-Nav1.6 signaling network, which leads to hyperexcitability. Hyperexcitability of CA1 pyramidal neurons caused by infection was mitigated via an anti-TNF antibody and genetic silencing of FGF14 in CA1. Furthermore, knockdown of FGF14 in CA1 reduced sickness behavior caused by infection.

CONCLUSIONS

FGF14 may represent a therapeutic target for mitigating consequences of TNF-mediated neuroinflammation.

Cerebral Metabolic Crisis in Pediatric Cerebral Malaria

Cerebral metabolic energy crisis (CMEC), often defined as a cerebrospinal fluid (CSF) lactate: pyruvate ratio (LPR) >40, occurs in various diseases and is associated with poor neurologic outcomes. Cerebral malaria (CM) causes significant mortality and neurodisability in children worldwide. Multiple factors that could lead to CMEC are plausible in these patients, but its frequency has not been explored. Fifty-three children with CM were enrolled and underwent analysis of CSF lactate and pyruvate levels. All 53 patients met criteria for a CMEC (median CSF LPR of 72.9 [interquartile range [IQR]: 58.5-93.3]). Half of children met criteria for an ischemic CMEC (median LPR of 85 [IQR: 73-184]) and half met criteria for a nonischemic CMEC (median LPR of 60 [IQR: 54-79]. Children also underwent transcranial doppler ultrasound investigation. Cerebral blood flow velocities were more likely to meet diagnostic criteria for low flow (<2 standard deviation from normal) or vasospasm in children with an ischemic CMEC (73%) than in children with a nonischemic CMEC (20%, p  = 0.04). Children with an ischemic CMEC had poorer outcomes (pediatric cerebral performance category of 3-6) than those with a nonischemic CMEC (46 vs. 22%, p  = 0.03). CMEC was ubiquitous in this patient population and the processes underlying the two subtypes (ischemic and nonischemic) may represent targets for future adjunctive therapies.

Dynamic intravital imaging reveals reactive vessel-associated microglia play a protective role in cerebral malaria coagulopathy

Vascular congestion and coagulopathy have been shown to play a role in human and experimental cerebral malaria (eCM), but little is known about the role of microglia, or microglia-vascular interactions and hypercoagulation during disease progression in this fatal infection. Recent studies show microglia bind to fibrinogen, a glycoprotein involved in thrombosis. An eCM model of Plasmodium chabaudi infection in mice deficient in the regulatory cytokine IL-10 manifests neuropathology, including hypercoagulation with extensive fibrin(ogen) deposition and neuroinflammation. Intravital microscopy and immunofluorescence are applied to elucidate the role of microglia in eCM. Results show microgliosis and coagulopathy occur early in disease at 3 dpi (day post-infection), and both are exacerbated as disease progresses to 7dpi. Vessel associated microglia increase significantly at 7 dpi, and the expression of the microglial chemoattractant CCL5 (RANTES) is increased versus uninfected and localized with fibrin(ogen) in vessels. PLX3397 microglia depletion resulted in rapid behavioral decline, severe hypothermia, and greater increase in vascular coagulopathy. This study suggests that microglia play a prominent role in controlling infection-initiated coagulopathy and supports a model in which microglia play a protective role in cerebral malaria by migrating to and patrolling the cerebral vasculature, potentially regulating degree of coagulation during systemic inflammation.

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.

Malarial retinopathy in a preschool child: A case report with long-term paediatric and ophthamological follow-up

AIM

To report a paediatric case of retinopathy-positive cerebral malaria, emphasizing the clinical significance of long-term neurological and ophthalmological follow-up (5,5 years).

CASE REPORT

After a recent journey in Ghana, a 17-month-old African female child was admitted at the Paediatric Emergency Room with fever and vomiting. Blood smear confirmed a Plasmodium Falciparum parasitaemia. Iv quinine was promptly administered, but after a few hours, the child developed generalized seizures, requiring benzodiazepine therapy and assisted ventilation for severe desaturation. Brain imaging (CT and MRI), lumbar puncture and several electroencephalograms showed data compatible with cerebral involvement of malaria. Schepens ophthalmoscopy and Ret-Cam pictures acquisition revealed macular haemorrhages in the left eye with central whitening and bilateral capillary abnormalities, typical signs of malarial retinopathy. Antimalarial therapy and iv Levetiracetam allowed neurological improvement. Eleven days after the admission, the child was discharged, showing no neurological symptoms and with an improved EEG signal, a normalized fundus oculi and brain imaging. Neurological and ophthalmological long-term follow-up were conducted: EEG controls didn't reveal abnormalities and the complete ophthalmological assessment showed a regular visual acuity and fundus oculi, as well as a normal SD-OCT and electrophysiologic testing.

CONCLUSION

Cerebral malaria is a severe complication, characterized by a high fatality rate and challenging diagnosis. A helpful instrument for diagnostic and prognostic evaluation is the ophthalmological detection of malarial retinopathy and its monitoring over time. In our patient the long term visual follow-up didn't reveal any adverse outcome.

Probing cerebral malaria inflammation in 3D human brain microvessels

Sequestration of Plasmodium falciparum-infected erythrocytes (IEs) in the brain microcirculation is a hallmark of cerebral malaria (CM), which leads to endothelial activation, brain swelling, and death. Here, we probed CM inflammation in a perfusable 3D human brain microvessel model. 3D brain microvessels supported in vivo-like capacities for parasite binding and maturation in situ, leading to a distinct inflammatory response from the pro-inflammatory cytokine tumor necrosis factor α (TNF-α). By combining transcriptional analysis, imaging, and leukocyte perfusion, we showed that whereas TNF-α promotes a reversible inflammatory phenotype with widespread leukocyte recruitment, parasites induce unique stress response pathways and cause localized cell adhesivity changes, focal endothelial disruptions, and apoptosis. Furthermore, parasites modified the temporal kinetics of the TNF transcriptional response, suggesting augmented inflammatory damage with the two sequential stimuli. Our findings offer mechanistic insights into CM biology in a 3D brain microvessel mimetic platform and suggest that multiple events intersect to promote brain barrier inflammation in CM.

Point-of-care Ultrasound to Assess Hemodynamic Contributors to Acute Kidney Injury in Pediatric Patients With Cerebral Malaria: A Pilot Study

BACKGROUND

Acute kidney injury is common in severe malaria and is independently associated with mortality. The pathogenesis of acute kidney injury (AKI) in severe malaria remains incompletely understood. Ultrasound-based tools such as point-of-care ultrasound (POCUS), ultrasound cardiac output monitors (USCOMs) and renal arterial resistive index (RRI) can be used to detect hemodynamic and renal blood flow abnormalities contributing to AKI in malaria.

METHODS

We conducted a prospective study of Malawian children with cerebral malaria to determine the feasibility of using POCUS and USCOM to characterize hemodynamic contributors to severe AKI (Kidney Disease: Improving Global Outcomes stage 2 or 3). The primary outcome was feasibility (completion rate of study procedures). We also assessed for differences in POCUS and hemodynamic variables for patients with or without severe AKI.

RESULTS

We enrolled 27 patients who had admission cardiac and renal ultrasounds and USCOM. Completion rates were high for cardiac (96%), renal (100%) and USCOM studies (96%). Severe AKI occurred in 13 of 27 patients (48%). No patients had ventricular dysfunction. Only 1 patient in the severe AKI group was determined to be hypovolemic ( P = 0.64). No significant differences in USCOM, RRI or venous congestion parameters were detected among patients with and without severe AKI. Mortality was 11% (3/27) with the 3 deaths occurring in the severe AKI group ( P = 0.056).

CONCLUSIONS

Ultrasound-based cardiac, hemodynamic and renal blood flow measurements appear to be feasible in pediatric patients with cerebral malaria. We were unable to detect hemodynamic or renal blood flow abnormalities contributing to severe AKI in cerebral malaria. Larger studies are needed to corroborate these findings.

Haematological parameters and their correlation with the degree of malaria parasitaemia among outpatients attending a polyclinic

BACKGROUND

Malaria is a parasitic disease caused by various species of the blood parasite Plasmodium; of all the parasitic diseases, malaria has the highest prevalence and mortality with an estimated 247 million cases and 619,000 deaths recorded worldwide as of 2021. Malaria causes febrile illness with several changes in blood cell parameters. Some of these changes include leucopenia, thrombocytopenia, and anaemia. If these changes could be correlated with the degree of parasitaemia, it can serve as a guide to physicians when treating malaria. This study was therefore aimed at correlating haematological parameters with levels of parasitaemia during malaria infection.

METHODS

The study was a cross-sectional study involving 89 malaria positive patients. About 5 ml of blood was collected from each participant who gave his or her informed consent to partake in the study. A full blood count was performed on their samples to determine their haematological parameters using a haematology auto-analyzer. A parasite count was also performed via microscopy to determine the degree of parasitaemia. The data obtained from the study was entered into a database and statistically analysed using Statistical Package for Social Sciences (SPSS) version 23 and Microsoft Excel 2016.

RESULTS

The study comprised of 89 participants out of which 35 were males and 54 were females with the mean age of 26.15 years. Secondary education participants were the highest with quaternary education the lowest. The highest parasite count recorded was 398,174 parasites/µl of blood, lowest count was 101 with the average being 32,942.32584. There was also a significant positive Pearson's correlation between total WBC and parasitaemia and with the WBC differentials, neutrophils, lymphocytes and monocytes had positive correlations while eosinophils and basophils had negative correlations. Furthermore, platelets, total RBC's, haemoglobin, MCH, MCHC and Hct all showed negative correlations. Linear regression also showed a linear relationship between parasite density and the various haematological parameters.

CONCLUSION

The linear relationship (correlation) between WBC and MCH were the only significant ones at 95% and 99% confidence interval, respectively based on a two-tail t-test. Also, based on the regression analysis, the changes caused by WBC and PLT were the only significant changes at 95% confidence level in a two-tailed t-test.

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.

Endothelial type I interferon response and brain diseases: identifying STING as a therapeutic target

The endothelium layer lining the inner surface of blood vessels serves relevant physiological functions in all body systems, including the exchanges between blood and extravascular space. However, endothelial cells also participate in innate and adaptive immune response that contribute to the pathophysiology of inflammatory disorders. Type I Interferon (IFN) signaling is an inflammatory response triggered by a variety of pathogens, but it can also be induced by misplaced DNA in the cytosol caused by cell stress or gene mutations. Type I IFN produced by blood leukocytes or by the endothelium itself is well-known to activate the interferon receptor (IFNAR) in endothelial cells. Here, we discuss the induction of type I IFN secretion and signaling in the endothelium, specifically in the brain microvasculature where endothelial cells participate in the tight blood-brain barrier (BBB). This barrier is targeted during neuroinflammatory disorders such as infection, multiple sclerosis, Alzheimer's disease and traumatic brain injury. We focus on type I IFN induction through the cGAS-STING activation pathway in endothelial cells in context of autoinflammatory type I interferonopathies, inflammation and infection. By comparing the pathophysiology of two separate infectious diseases-cerebral malaria induced by Plasmodium infection and COVID-19 caused by SARS-CoV-2 infection-we emphasize the relevance of type I IFN and STING-induced vasculopathy in organ dysfunction. Investigating the role of endothelial cells as active type I IFN producers and responders in disease pathogenesis could lead to new therapeutic targets. Namely, endothelial dysfunction and brain inflammation may be avoided with strategies that target excessive STING activation in endothelial cells.

Increased brain microvascular hemoglobin concentrations in children with cerebral malaria

Brain swelling is associated with death from cerebral malaria, but it is unclear whether brain swelling is caused by cerebral edema or vascular congestion-two pathological conditions with distinct effects on tissue hemoglobin concentrations. We used near-infrared spectroscopy (NIRS) to noninvasively study cerebral microvascular hemoglobin concentrations in 46 Malawian children with cerebral malaria. Cerebral malaria was defined by the presence of the malaria parasite Plasmodium falciparum on a blood smear, a Blantyre coma score of 2 or less, and retinopathy. Children with uncomplicated malaria (n = 33) and healthy children (n = 29) were enrolled as comparators. Cerebral microvascular hemoglobin concentrations were higher among children with cerebral malaria compared with those with uncomplicated malaria [median (25th, 75th): 145.2 (95.2, 190.0) μM versus 82.9 (65.7, 105.4) μM, P = 0.008]. Cerebral microvascular hemoglobin concentrations correlated with brain swelling score determined by MRI (r = 0.37, P = 0.03). Fluctuations in cerebral microvascular hemoglobin concentrations over a 30-min time period were characterized using detrended fluctuation analysis (DFA). DFA determined self-similarity of the cerebral microvascular hemoglobin concentration signal to be lower among children with cerebral malaria compared with those with uncomplicated malaria [0.63 (0.54, 0.70) versus 0.91 (0.82, 0.94), P < 0.0001]. The lower self-similarity of the hemoglobin concentration signal in children with cerebral malaria suggested impaired regulation of cerebral blood flow. The elevated cerebral tissue hemoglobin concentration and its correlation with brain swelling suggested that excess blood volume, potentially due to vascular congestion, may contribute to brain swelling in cerebral malaria.

Association of severe malaria with cognitive and behavioural outcomes in low- and middle-income countries: a meta-analysis and systematic review

BACKGROUND

Malaria affects 24 million children globally, resulting in nearly 500,000 child deaths annually in low- and middle-income countries (LMICs). Recent studies have provided evidence that severe malaria infection results in sustained impairment in cognition and behaviour among young children; however, a formal meta-analysis has not been published. The objective was to assess the association between severe malaria infection with cognitive and behavioural outcomes among children living in LMICs.

METHODS

Six online bibliographic databases were searched and reviewed in November 2022. Studies included involved children < 18 years of age living in LMICs with active or past severe malaria infection and measured cognitive and/or behaviour outcomes. The quality of studies was assessed. Definitions of severe malaria included cerebral malaria, severe malarial anaemia, and author-defined severe malaria. Results from all studies were qualitatively summarized. For studies with relevant data on attention, learning, memory, language, internalizing behaviour and externalizing behaviour, results were pooled and a meta-analysis was performed. A random-effects model was used across included cohorts, yielding a standardized mean difference between the severe malaria group and control group.

RESULTS

Out of 3,803 initial records meeting the search criteria, 24 studies were included in the review, with data from 14 studies eligible for meta-analysis inclusion. Studies across sub-Saharan Africa assessed 11 cohorts of children from pre-school to school age. Of all the studies, composite measures of cognition were the most affected areas of development. Overall, attention, memory, and behavioural problems were domains most commonly found to have lower scores in children with severe malaria. Meta-analysis revealed that children with severe malaria had worse scores compared to children without malaria in attention (standardized mean difference (SMD) -0.68, 95% CI -1.26 to -0.10), memory (SMD -0.52, 95% CI -0.99 to -0.06), and externalizing behavioural problems (SMD 0.45, 95% CI 0.13-0.78).

CONCLUSION

Severe malaria is associated with worse neuropsychological outcomes for children living in LMICs, specifically in attention, memory, and externalizing behaviours. More research is needed to identify the long-term implications of these findings. Further interventions are needed to prevent cognitive and behavioural problems after severe malaria infection.

TRIAL REGISTRATION

This systematic review was registered under PROSPERO: CRD42020154777.

Increased Neutrophil Percentage and Neutrophil-T Cell Ratio Precedes Clinical Onset of Experimental Cerebral Malaria

Newly emerging data suggest that several neutrophil defense mechanisms may play a role in both aggravating and protecting against malaria. These exciting findings suggest that the balance of these cells in the host body may have an impact on the pathogenesis of malaria. To fully understand the role of neutrophils in severe forms of malaria, such as cerebral malaria (CM), it is critical to gain a comprehensive understanding of their behavior and functions. This study investigated the dynamics of neutrophil and T cell responses in C57BL/6 and BALB/c mice infected with Plasmodium berghei ANKA, murine models of experimental cerebral malaria (ECM) and non-cerebral experimental malaria, respectively. The results demonstrated an increase in neutrophil percentage and neutrophil-T cell ratios in the spleen and blood before the development of clinical signs of ECM, which is a phenomenon not observed in the non-susceptible model of cerebral malaria. Furthermore, despite the development of distinct forms of malaria in the two strains of infected animals, parasitemia levels showed equivalent increases throughout the infection period evaluated. These findings suggest that the neutrophil percentage and neutrophil-T cell ratios may be valuable predictive tools for assessing the dynamics and composition of immune responses involved in the determinism of ECM development, thus contributing to the advancing of our understanding of its pathogenesis.

Knobs, Adhesion, and Severe Falciparum Malaria

Plasmodium falciparum can cause a severe disease with high mortality. A major factor contributing to the increased virulence of P. falciparum, as compared to other human malarial parasites, is the sequestration of infected erythrocytes in the capillary beds of organs and tissues. This sequestration is due to the cytoadherence of infected erythrocytes to endothelial cells. Cytoadherence is primarily mediated by a parasite protein expressed on the surface of the infected erythrocyte called P. falciparum erythrocyte membrane protein-1 (PfEMP1). PfEMP1 is embedded in electron-dense protuberances on the surface of the infected erythrocytes called knobs. These knobs are assembled on the erythrocyte membrane via exported parasite proteins, and the knobs function as focal points for the cytoadherence of infected erythrocytes to endothelial cells. PfEMP1 is a member of the var gene family, and there are approximately 60 antigenically distinct PfEMP1 alleles per parasite genome. Var gene expression exhibits allelic exclusion, with only a single allele being expressed by an individual parasite. This results in sequential waves of antigenically distinct infected erythrocytes and this antigenic variation allows the parasite to establish long-term chronic infections. A wide range of endothelial cell receptors can bind to the various PfEMP1 alleles, and thus, antigenic variation also results in a change in the cytoadherence phenotype. The cytoadherence phenotype may result in infected erythrocytes sequestering in different tissues and this difference in sequestration may explain the wide range of possible clinical manifestations associated with severe falciparum malaria.

Memory CD8+ T cell-mediated protection against liver-stage malaria

Nearly half of the world's population is at risk of malaria, a disease caused by the protozoan parasite Plasmodium, which is estimated to cause more than 240,000,000 infections and kill more than 600,000 people annually. The emergence of Plasmodia resistant to chemoprophylactic treatment highlights the urgency to develop more effective vaccines. In this regard, whole sporozoite vaccination approaches in murine models and human challenge studies have provided substantial insight into the immune correlates of protection from malaria. From these studies, CD8+ T cells have come to the forefront, being identified as critical for vaccine-mediated liver-stage immunity that can prevent the establishment of the symptomatic blood stages and subsequent transmission of infection. However, the unique biological characteristics required for CD8+ T cell protection from liver-stage malaria dictate that more work must be done to design effective vaccines. In this review, we will highlight a subset of studies that reveal basic aspects of memory CD8+ T cell-mediated protection from liver-stage malaria infection.

Neuroprotection by Alstonia boonei De Wild., Anacardium occidentale L., Azadirachta indica A.Juss. and Mangifera indica L

ETHNOPHARMACOLOGY RELEVANCE

Alstonia boonei De Wild. (stem bark), Anacardium occidentale L. (stem bark), Azadirachta indica A.Juss (leaves), Enantia chlorantha Oliv. (stem bark), Khaya senegalensis A.Juss (stem bark) Mangifera indica L. (stem bark), and Nauclea latifolia Sm. (stem bark) are used for treating malaria in southwest Nigeria. Surveys revealed that these plants are also employed for treating symptoms of malaria and cerebral malaria in the region.

AIM OF THE STUDY

In this study, the effects of freeze-dried extracts of these plants were investigated on synthetic hemozoin (HZ)-induced neuroinflammation, neuronal damage, and increased permeability of brain microvascular endothelial cells.

MATERIALS AND METHODS

Effects of freeze-dried plant extracts were investigated on neuroinflammation by measuring levels of pro-inflammatory mediators in culture supernatants, while in-cell western assays were used to measure protein levels of iNOS and NLRP3. Effects on HZ-induced neurotoxicity and ROS generation was measured using MTT and DCFDA assays, respectively. HZ-induced permeability of hCMEC/D3 endothelial cells was determined using the in vitro vascular permeability assay kit.

RESULTS

The extracts produced significant (p < 0.05) reduction in TNFα, IL-6, IL-1β, MCP-1, RANTES and iNOS/NO production in HZ-stimulated BV-2 microglia. Pre-treatment with 50 μg/mL of A. boonei, A. indica, A. occidentale, E. chlorantha and M. indica also resulted in the inhibition of NF-κB activation. Pre-treatment with A. indica produced, A. occidentale, M. indica and A. boonei reduced HZ-induced increased NLRP3 protein expression. HZ-induced increased caspase-1 activity was also reduced by A. boonei, A. occidentale, A. indica, E. chlorantha, and M. indica. Freeze-dried extracts of A. boonei, A. occidentale, A. indica and M. indica produced neuroprotective effect in HT-22 neuronal cells incubated with HZ by preventing HZ-induced neurotoxicity, ROS generation, DNA fragmentation and caspase 3/7 activity. Inhibition of HZ-induced increase in permeability of human hCMEC/D3 brain endothelial cells was also observed with A. boonei, A. occidentale, A. indica and M. indica, while reducing the release of TNFα and MMP-9.

CONCLUSIONS

These results suggest that A. boonei, A. occidentale, A. indica and M. indica are neuroprotective through inhibition of neuroinflammation, neuronal damage and increased permeability of blood brain barrier. The outcome of the study provides pharmacological evidence for the potential benefits of plants as herbal treatments for cerebral malaria symptoms.

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.

Cerebral Malaria Is Regulated by Host-Mediated Changes in Plasmodium Gene Expression

Cerebral malaria (CM), the deadliest complication of Plasmodium infection, is a complex and unpredictable disease. However, our understanding of the host and parasite factors that cause CM is limited. Using a mouse model of CM, experimental CM (ECM), we performed a three-way comparison between ECM-susceptible C57BL/6 mice infected with ECM-causing Plasmodium ANKA parasites [ANKA(C57BL/6)], ECM-resistant BALB/c mice infected with Plasmodium ANKA [ANKA(BALB/c)], and C57BL/6 mice infected with Plasmodium NK65 that does not cause ECM [NK65(C57BL/6)]. All ANKA(C57BL/6) mice developed CM. In contrast, in ANKA(BALB/c) and NK65(C57BL/6), infections do not result in CM and proceed similarly in terms of parasite growth, disease course, and host immune response. However, parasite gene expression in ANKA(BALB/c) was remarkably different than that in ANKA(C57BL/6) but similar to the gene expression in NK65(C57BL/6). Thus, Plasmodium ANKA has an ECM-specific gene expression profile that is activated only in susceptible hosts, providing evidence that the host has a critical influence on the outcome of infection. IMPORTANCE Hundreds of thousands of lives are lost each year due to the brain damage caused by malaria disease. The overwhelming majority of these deaths occur in young children living in sub-Saharan Africa. Thus far, there are no vaccines against this deadly disease, and we still do not know why fatal brain damage occurs in some children while others have milder, self-limiting disease progression. Our research provides an important clue to this problem. Here, we showed that the genetic background of the host has an important role in determining the course and the outcome of the disease. Our research also identified parasite molecules that can potentially be targeted in vaccination and therapy approaches.

Exploring the potential of antimalarial nanocarriers as a novel therapeutic approach

Malaria is a life-threatening parasitic disease that affects millions of people worldwide, especially in developing countries. Despite advances in conventional therapies, drug resistance in malaria parasites has become a significant concern. Hence, there is a need for a new therapeutic approach. To combat the disease effectively means eliminating vectors and discovering potent treatments. The nanotechnology research efforts in nanomedicine show promise by exploring the potential use of nanomaterials that can surmount these limitations occurring with antimalarial drugs, which include multidrug resistance or lack of specificity when targeting parasites directly. Utilizing nanomaterials would possess unique advantages over conventional chemotherapy systems by increasing the efficacy levels while reducing side effects significantly by delivering medications precisely within the diseased area. It also provides cheap yet safe measures against Malaria infections worldwide-ultimately improving treatment efficiency holistically without reinventing new methods therapeutically. This review is an effort to provide an overview of the various stages of malaria parasites, pathogenesis, and conventional therapies, as well as the treatment gap existing with available formulations. It explores different types of nanocarriers, such as liposomes, ethosomal cataplasm, solid lipid nanoparticles, nanostructured lipid carriers, polymeric nanocarriers, and metallic nanoparticles, which are frequently employed to boost the efficiency of antimalarial drugs to overcome the challenges and develop effective and safe therapies. The study also highlights the improved pharmacokinetics, enhanced drug bioavailability, and reduced toxicity associated with nanocarriers, making them a promising therapeutic approach for treating malaria.

Synthesis and antimalarial activity of amide and ester conjugates of siderophores and ozonides

Despite advances in chemotherapeutic interventions for the treatment of malaria, there is a continuing need for the development of new antimalarial agents. Previous studies indicated that co-administration of chloroquine with antioxidants such as the iron chelator deferoxamine (DFO) prevented the development of persistent cognitive damage in surrogate models of cerebral malaria. The work described herein reports the syntheses and antimalarial activities of covalent conjugates of both natural (siderophores) and artificial iron chelators, namely DFO, ferricrocin and ICL-670, with antimalarial 1,2,4-trioxolanes (ozonides). All of the synthesized conjugates had potent antimalarial activities against the in vitro cultures of drug resistant and drug sensitive strains of Plasmodium falciparum. The work described herein provides the basis for future development of covalent combination of iron chelators and antimalarial chemotherapeutic agents for the treatment of cerebral malaria.

Pathogenesis of Cerebral Malaria: New Trends and Insights for Developing Adjunctive Therapies

No specific or adjunctive therapies exist to treat cerebral malaria (CM) as of date. CM is a neuropathological manifestation of the malaria infection in humans, caused by the hemoparasitic pathogen Plasmodium falciparum. Driven through a multitude of virulence factors, varied immune responses, variations in brain swelling with regard to the age of patients, parasite biomass, and parasite-typing, the essential pathogenetic mechanisms underlying clinical CM have remained elusive. However, a recent series of studies based on molecular, immunologic, and advanced neuroradiologic and machine-learning approaches have unraveled new trends and insights to better understand and focus on the key determinants of CM in humans. This could possibly be the beginning of the design of new and effective adjunctive therapies that may not be common or applicable to the entire malarious world, but that could, rather, be specific to the variations in the determinants of CM.

Misidentification of Plasmodium Species by Cross-Reacting Primers and Cerebral Malaria Caused by Plasmodium vivax

Introduction The clinical presentation of a case as cerebral malaria with molecular identification confirming it as Plasmodium vivax underlines the importance of using molecular tools to identify the species and type of malaria. The possibility of the relationship between the complication observed during clinical diagnosis and the multifactorial molecular changes could likely be the reason for terming it cerebral malaria.

Methods We report four cases analyzed using the quantitative buffy coat technique followed by classical Giemsa stained thick-film microscopy, and nested polymerase chain reaction for the genus-specific region of Plasmodium targeting 18S rDNA followed by species-specific identification with a different set of primers and products confirmation with sequencing.

Results Primers targeting P. knowlesi generated the expected product size of 153 base pairs that, upon sequencing, matched with the P. vivax sequence reflecting the relatedness of the species. Likewise, primers targeting P. ovale generated a 456 product whose sequence matched the P. vivax sequence.

Conclusion Infection with P. vivax can potentially cause cerebral malaria, and P. vivax can cause severe malaria complications alone or mixed with other species and can show cerebral malaria signs, which are typically associated with P. falciparum infections. The sequence relatedness reflects the genome similarity between P. knowlesi and P. ovale with P. vivax. The need to reconfirm with an additional set of newly reported primers is mandatory.

Mechanistic insights into immunopathogenesis of murine cerebral malaria: Cues from "young" C57BL/6J and BALB/c mice

Cerebral malaria (CM), a major cause of mortality in children <5 years, presents disparity in pathophysiological features and poor prognosis compared to adults. Adult C57BL/6J mice infected with Plasmodium berghei ANKA (PbA) are widely used to understand CM pathogenesis compared to relatively less prone BALB/c mice; however, age and immune status of the host also influence disease sequelae and cerebral manifestations. Murine models of CM known so far do not project complete disease spectrum of pediatric CM. The present study was designed to dissect and differentiate CM immunopathogenesis in "young" BALB/c and C57BL/6J mice infected with PbA, in search of a competent mouse model mimicking pediatric CM. Multipronged approach including the analysis of blood-brain barrier (BBB) permeability and parasite infiltration, histopathology, nitric oxide levels, and pro/anti-inflammatory (TNF-α, IFN-γ, IL-4, and IL-10) cytokine expression were compared in the cortices of both young BALB/c and C57BL/6J mice. The results illustrate severe course of infection and typical CM like histopathological alterations including monocytic plugging in PbA-infected "young" BALB/c compared to C57BL/6J mice. The decreased expression of tight junction proteins (ZO-1 and Claudin-3) and Evan's blue extravasation was also more evident in BALB/c mice indicating a more permeable BBB. The increased cortical expression of TNF-α, IFN-γ, IL-4, IL-10, iNOS, eNOS, nNOS, and associated activation of brain resident cells in cortices of BALB/c with progressive parasitaemia depicts the cumulative involvement of host immune responses and parasite accumulation in progression of CM. Thus, the incongruity of cytokine balance resulted in worsening of disease manifestation in "young" BALB/c similar to pediatric CM.

Altered gastrointestinal tract structure and microbiome following cerebral malaria infection

Cerebral malaria (CM) is the most severe form of malaria with the highest mortality rate and can result in life-long neurological deficits and ongoing comorbidities. Factors contributing to severity of infection and development of CM are not fully elucidated. Recent studies have indicated a key role of the gut microbiome in a range of health conditions that affect the brain, but limited microbiome research has been conducted in the context of malaria. To address this knowledge gap, the impact of CM on the gut microbiome was investigated in mice. C57BL/6J mice were infected with Plasmodium berghei ANKA (PbA) parasites and compared to non-infected controls. Microbial DNA from faecal pellets collected daily for 6-days post-infection were extracted, and microbiome comparisons conducted using 16S rRNA profiling. We identified significant differences in the composition of bacterial communities between the infected and the non-infected groups, including a higher abundance of the genera Akkermansia, Alistipes and Alloprevotella in PbA-infected mice. Furthermore, intestinal samples were collected post-cull for morphological analysis. We determined that the caecal weight was significantly lower, and the small intestine was significantly longer in PbA-infected mice than in the non-infected controls. We concluded that changes in microbial community composition were primarily driven by the infection protocol and, to a lesser extent, by the time of infection. Our findings pave the way for a new area of research and novel intervention strategies to modulate the severity of cerebral malaria disease.

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.

Survey study of the etiology of non-traumatic altered consciousness in the Emergency Department at Suez Canal University Hospital in Egypt

BACKGROUND

Disorders of consciousness including coma in non-trauma patients can be caused by a wide variety of pathologies affecting the central nervous system. They represent a frequent challenge in emergency medicine and are combined with a very high in-hospital mortality. Hence, early treatment of these patients is vital and increases the likelihood of a good outcome.

AIM

To identify the causes of altered consciousness presentation to the Emergency Department at Suez Canal University Hospital.

METHODS

This was a descriptive cross-sectional study conducted on 87 patients with acute non-traumatic disturbed level of consciousness (DLOC) at the Emergency Department.

RESULTS

The mean age of the studied patients was 60.5 ± 13.6 years. Among them, 60% were males and 40% were females. The most common cause of acute non-traumatic DLOC was systemic infection, such as sepsis and septic shock (25.3%), followed by respiratory causes (24.1%) and neurological causes (18.4%).

CONCLUSION

The most common cause of acute non-traumatic DLOC was systemic infections followed by respiratory and neurological causes.

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.

Theta-Alpha Variability on Admission EEG Is Associated With Outcome in Pediatric Cerebral Malaria

PURPOSE

Pediatric cerebral malaria has high rates of mortality and neurologic morbidity. Although several biomarkers, including EEG, are associated with survival or morbidity, many are resource intensive or require skilled interpretation for clinical use. Automation of quantitative interpretation of EEG may be preferable in resource-limited settings, where trained interpreters are rare. As currently used quantitative EEG factors do not adequately describe the spectrum of variability seen in studies from children with cerebral malaria, the authors developed and validated a new quantitative EEG variable, theta-alpha variability (TAV).

METHODS

The authors developed TAV, a new quantitative variable, as a composite of multiple automated EEG outputs. EEG records from 194 children (6 months to 14 years old) with cerebral malaria were analyzed. Independent EEG interpreters performed standard quantitative and qualitative analyses, with the addition of the newly created variable. The associations of TAV with other quantitative EEG factors, a qualitative assessment of variability, and outcomes were assessed.

RESULTS

Theta-alpha variability was not highly correlated with alpha, theta, or delta power and was not associated with qualitative measures of variability. Children whose EEGs had higher values of TAV had a lower risk of death (odds ratio = 0.934, 95% confidence interval = 0.902-0.966) or neurologic sequelae (odds ratio = 0.960, 95% confidence interval = 0.932-0.990) compared with those with lower values. Receiver operating characteristic analysis in predicting death at a TAV threshold of 0.244 yielded a sensitivity of 74% and specificity of 70% for an area under the receiver operating characteristic curve of 0.755.

CONCLUSIONS

Theta-alpha variability is independently associated with outcome in pediatric cerebral malaria and can predict death with high sensitivity and specificity. Automated determination of this newly created EEG factor holds promise as a potential method to increase the clinical utility of EEG in resource-limited settings by allowing interventions to be targeted to those at higher risk of death or disability.

Erythrocyte membrane with CLIPPKF as biomimetic nanodecoy traps merozoites and attaches to infected red blood cells to prevent Plasmodium infection

BACKGROUND

Malaria remains a serious threat to global public health. With poor efficacies of vaccines and the emergence of drug resistance, novel strategies to control malaria are urgently needed.

RESULTS

We developed erythrocyte membrane-camouflaged nanoparticles loaded with artemether based on the growth characteristics of Plasmodium. The nanoparticles could capture the merozoites to inhibit them from repeatedly infecting normal erythrocytes, owing to the interactions between merozoites and heparin-like molecules on the erythrocyte membrane. Modification with a phosphatidylserine-targeting peptide (CLIPPKF) improved the drug accumulation in infected red blood cells (iRBCs) from the externalized phosphatidylserine induced by Plasmodium infection. In Plasmodium berghei ANKA strain (pbANKA)-infected C57BL/6 mice, the nanoparticles significantly attenuated Plasmodium-induced inflammation, apoptosis, and anemia. We observed reduced weight variation and prolonged survival time in pbANKA-challenged mice, and the nanoparticles showed good biocompatibility and negligible cytotoxicity.

CONCLUSION

Erythrocyte membrane-camouflaged nanoparticles loaded with artemether were shown to provide safe and effective protection against Plasmodium infection.

Rational-Based Discovery of Novel β-Carboline Derivatives as Potential Antimalarials: From In Silico Identification of Novel Targets to Inhibition of Experimental Cerebral Malaria

Malaria is an infectious disease widespread in underdeveloped tropical regions. The most severe form of infection is caused by Plasmodium falciparum, which can lead to development of cerebral malaria (CM) and is responsible for deaths and significant neurocognitive sequelae throughout life. In this context and considering the emergence and spread of drug-resistant P. falciparum isolates, the search for new antimalarial candidates becomes urgent. β-carbolines alkaloids are good candidates since a wide range of biological activity for these compounds has been reported. Herein, we designed 20 chemical entities and performed an in silico virtual screening against a pool of P. falciparum molecular targets, the Brazilian Malaria Molecular Targets (BRAMMT). Seven structures showed potential to interact with PfFNR, PfPK7, PfGrx1, and PfATP6, being synthesized and evaluated for in vitro antiplasmodial activity. Among them, compounds 3−6 and 10 inhibited the growth of the W2 strain at µM concentrations, with low cytotoxicity against the human cell line. In silico physicochemical and pharmacokinetic properties were found to be favorable for oral administration. The compound 10 provided the best results against CM, with important values of parasite growth inhibition on the 5th day post-infection for both curative (67.9%) and suppressive (82%) assays. Furthermore, this compound was able to elongate mice survival and protect them against the development of the experimental model of CM (>65%). Compound 10 also induced reduction of the NO level, possibly by interaction with iNOS. Therefore, this alkaloid showed promising activity for the treatment of malaria and was able to prevent the development of experimental cerebral malaria (ECM), probably by reducing NO synthesis.