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 (ß = -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 (ß = -1.08; 95% CI, -1.79 to -0.38; P = .003) and working memory (ß = -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.

Elimination of intravascular thrombi prevents early mortality and reduces gliosis in hyper-inflammatory experimental cerebral malaria.

BACKGROUND: Cerebral malaria (CM) is the most lethal outcome of Plasmodium infection. There are clear correlations between expression of inflammatory cytokines, severe coagulopathies, and mortality in human CM. However, the mechanisms intertwining the coagulation and inflammation pathways, and their roles in CM, are only beginning to be understood. In mice with T cells deficient in the regulatory cytokine IL-10 (IL-10 KO), infection with Plasmodium chabaudi leads to a hyper-inflammatory response and lethal outcome that can be prevented by anti-TNF treatment. However, inflammatory T cells are adherent within the vasculature and not present in the brain parenchyma, suggesting a novel form of cerebral inflammation. We have previously documented behavioral dysfunction and microglial activation in infected IL-10 KO animals suggestive of neurological involvement driven by inflammation. In order to understand the relationship of intravascular inflammation to parenchymal dysfunction, we studied the congestion of vessels with leukocytes and fibrin(ogen) and the relationship of glial cell activation to congested vessels in the brains of P. chabaudi-infected IL-10 KO mice. METHODS: Using immunofluorescence microscopy, we describe severe thrombotic congestion in these animals. We stained for immune cell surface markers (CD45, CD11b, CD4), fibrin(ogen), microglia (Iba-1), and astrocytes (GFAP) in the brain at the peak of behavioral symptoms. Finally, we investigated the roles of inflammatory cytokine tumor necrosis factor (TNF) and coagulation on the pathology observed using neutralizing antibodies and low-molecular weight heparin to inhibit both inflammation and coagulation, respectively. RESULTS: Many blood vessels in the brain were congested with thrombi containing adherent leukocytes, including CD4 T cells and monocytes. Despite containment of the pathogen and leukocytes within the vasculature, activated microglia and astrocytes were prevalent in the parenchyma, particularly clustered near vessels with thrombi. Neutralization of TNF, or the coagulation cascade, significantly reduced both thrombus formation and gliosis in P. chabaudi-infected IL-10 KO mice. CONCLUSIONS: These findings support the contribution of cytokines, coagulation, and leukocytes within the brain vasculature to neuropathology in malaria infection. Strikingly, localization of inflammatory leukocytes within intravascular clots suggests a mechanism for interaction between the two cascades by which cytokines drive local inflammation without considerable cellular infiltration into the brain parenchyma.

Mesenchymal stromal cell therapy attenuated lung and kidney injury but not brain damage in experimental cerebral malaria.

INTRODUCTION: Malaria is the most relevant parasitic disease worldwide, and still accounts for 1 million deaths each year. Since current antimalarial drugs are unable to prevent death in severe cases, new therapeutic strategies have been developed. Mesenchymal stromal cells (MSC) confer host resistance against malaria; however, thus far, no study has evaluated the therapeutic effects of MSC therapy on brain and distal organ damage in experimental cerebral malaria. METHODS: Forty C57BL/6 mice were injected intraperitoneally with 5 × 10(6) Plasmodium berghei-infected erythrocytes or saline. After 24 h, mice received saline or bone marrow (BM)-derived MSC (1x10(5)) intravenously and were housed individually in metabolic cages. After 4 days, lung and kidney morphofunction; cerebrum, spleen, and liver histology; and markers associated with inflammation, fibrogenesis, and epithelial and endothelial cell damage in lung tissue were analyzed. RESULTS: In P. berghei-infected mice, BM-MSCs: 1) reduced parasitemia and mortality; 2) increased phagocytic neutrophil content in brain, even though BM-MSCs did not affect the inflammatory process; 3) decreased malaria pigment detection in spleen, liver, and kidney; 4) reduced hepatocyte derangement, with an increased number of Kupffer cells; 5) decreased kidney damage, without effecting significant changes in serum creatinine levels or urinary flow; and 6) reduced neutrophil infiltration, interstitial edema, number of myofibroblasts within interstitial tissue, and collagen deposition in lungs, resulting in decreased lung static elastance. These morphological and functional changes were not associated with changes in levels of tumor necrosis factor-α, keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8), or interferon-γ, which remained increased and similar to those of P. berghei animals treated with saline. BM-MSCs increased hepatocyte growth factor but decreased VEGF in the P. berghei group. CONCLUSIONS: BM-MSC treatment increased survival and reduced parasitemia and malaria pigment accumulation in spleen, liver, kidney, and lung, but not in brain. The two main organs associated with worse prognosis in malaria, lung and kidney, sustained less histological damage after BM-MSC therapy, with a more pronounced improvement in lung function.

Spleen volume and clinical disease manifestations of severe Plasmodium falciparum malaria in African children.

BACKGROUND: Plasmodium falciparum malaria is common in African children. Severe disease manifestations include severe malarial anemia (SMA) and cerebral malaria (CM). In vitro studies suggest that splenic sequestration is associated with SMA and protective against CM. We sought to characterize the relationship between ultrasonographically derived spleen volume (SV), clinical manifestations and outcome. METHODS: We conducted a prospective observational study of severe malaria and SV in children aged 3 months to 12 years in Eastern Uganda. An SV normogram was generated from 186 healthy controls and adjusted for total body surface area (TBSA). Children with severe P. falciparum malaria were classified according to disease phenotype, and SV z-scores were compared for cases and controls to assess the degree of spleen enlargement. RESULTS: One hundred and four children with severe malaria, median age 19.2 months, were enrolled; 54 were classified as having SMA and 15 with CM. Mortality was 27% in the CM group vs 1.9% in the SMA group. TBSA-adjusted SV z-scores were lower in children with CM compared to SMA (1.98 [95% CI 1.38-2.57] vs 2.73 [95% CI 2.41-3.04]; p=0.028). Mean SV z-scores were lower in children who died (1.20 [95% CI 0.14-2.25]) compared to survivors (2.58 [95% CI 2.35-2.81]); p=0.004. CONCLUSIONS: SV is lower in CM compared to SMA. Severe malaria with no increase in SV z-score may be associated with mortality.

Supraorbital postmortem brain sampling for definitive quantitative confirmation of cerebral sequestration of Plasmodium falciparum parasites.

BACKGROUND: The conventional clinical case definition of cerebral malaria (CM) is imprecise but specificity is improved by a definitive clinical feature such as retinopathy or confirming sequestration of parasites in a post-mortem examination of the brain. A full autopsy is often not possible, since it is costly and may encounter resistance of the deceased's family. METHODS: We have assessed the use of a cytological smear of brain tissue, obtained post-mortem by supraorbital sampling, for the purpose of quantifying cerebral sequestration in children with fatal malaria in Blantyre, Malawi. We have compared this method to histological quantification of parasites at autopsy. RESULTS: The number of parasites present on cytological smears correlated with the proportion of vessels parasitized as assessed by histology of fixed and stained brain tissue. Use of cytological results in addition to the standard clinical case definition increases the specificity of the clinical case definition alone from 48.3% to 100% with a minimal change in sensitivity. CONCLUSIONS: Post-mortem supraorbital sampling of brain tissue improves the specificity of the diagnosis of fatal cerebral malaria and provides accurate quantitative estimates of cerebral sequestration. This tool can be of great value in clinical, pathogenetic, and epidemiological research studies on cerebral malaria.

Pentoxifylline as an adjunct therapy in children with cerebral malaria.

BACKGROUND: Pentoxifylline (PTX) affects many processes that may contribute to the pathogenesis of severe malaria and it has been shown to reduce the duration of coma in children with cerebral malaria. This pilot study was performed to assess pharmacokinetics, safety and efficacy of PTX in African children with cerebral malaria. METHODS: Ten children admitted to the high dependency unit of the Kilifi District Hospital in Kenya with cerebral malaria (Blantyre coma score of 2 or less) received quinine plus a continuous infusion of 10 mg/kg/24 hours PTX for 72 hours. Five children were recruited as controls and received normal saline instead of PTX. Plasma samples were taken for PTX and tumour necrosis factor (TNF) levels. Blantyre Coma Score, parasitemia, hematology and vital signs were assessed 4 hourly. RESULTS: One child (20%) in the control group died, compared to four children (40%) in the PTX group. This difference was not significant (p = 0.60). Laboratory parameters and clinical data were comparable between groups. TNF levels were lower in children receiving PTX. CONCLUSIONS: The small sample size does not permit definitive conclusions, but the mortality rate was unexpectedly high in the PTX group.

Glatiramer acetate reduces the risk for experimental cerebral malaria: a pilot study.

BACKGROUND: Cerebral malaria (CM) is associated with high mortality and morbidity caused by a high rate of transient or persistent neurological sequelae. Studies on immunomodulatory and neuroprotective drugs as ancillary treatment in murine CM indicate promising potential. The current study was conducted to evaluate the efficacy of glatiramer acetate (GA), an immunomodulatory drug approved for the treatment of relapsing remitting multiple sclerosis, in preventing the death of C57Bl/6J mice infected with Plasmodium berghei ANKA. METHODS AND RESULTS: GA treatment led to a statistically significant lower risk for developing CM (57.7% versus 84.6%) in treated animals. The drug had no effect on the course of parasitaemia. The mechanism of action seems to be an immunomodulatory effect since lower IFN-gamma levels were observed in treated animals in the early course of the disease (day 4 post-infection) which also led to a lower number of brain sequestered leukocytes in treated animals. No direct neuro-protective effect such as an inhibition of apoptosis or reduction of micro-bleedings in the brain was found. CONCLUSION: These findings support the important role of the host immune response in the pathophysiology of murine CM and might lead to the development of new adjunctive treatment strategies.

Failure of two distinct anti-apoptotic approaches to reduce mortality in experimental cerebral malaria.

Cerebral malaria is responsible for a high proportion of mortality in human Plasmodium falciparum infection. Previous studies have reported the presence of apoptosis in endothelial cells, astrocytes, neurons, and glial cells in experimental murine cerebral malaria caused by infection with Plasmodium berghei ANKA. Using this model, we tested two strategies, which have been shown to improve survival in murine models of sepsis: 1) treatment with z-VAD, a pancaspase inhibitor; and 2) overexpression of Bcl-2 using transgenic mice expressing human Bcl-2 (which prevents the release of apoptotic mediators from the mitochondria) from a myeloid cell promoter. Neither of these anti-apoptotic strategies, previously shown to provide therapeutic benefit in sepsis, improved survival in experimental cerebral malaria.

Blood-stage Plasmodium infection induces CD8+ T lymphocytes to parasite-expressed antigens, largely regulated by CD8alpha+ dendritic cells.

Although CD8(+) T cells do not contribute to protection against the blood stage of Plasmodium infection, there is mounting evidence that they are principal mediators of murine experimental cerebral malaria (ECM). At present, there is no direct evidence that the CD8(+) T cells mediating ECM are parasite-specific or, for that matter, whether parasite-specific CD8(+) T cells are generated in response to blood-stage infection. To resolve this and to define the cellular requirements for such priming, we generated transgenic P. berghei parasites expressing model T cell epitopes. This approach was necessary as MHC class I-restricted antigens to blood-stage infection have not been defined. Here, we show that blood-stage infection leads to parasite-specific CD8(+) and CD4(+) T cell responses. Furthermore, we show that P. berghei-expressed antigens are cross-presented by the CD8alpha(+) subset of dendritic cells (DC), and that this induces pathogen-specific cytotoxic T lymphocytes (CTL) capable of lysing cells presenting antigens expressed by blood-stage parasites. Finally, using three different experimental approaches, we provide evidence that CTL specific for parasite-expressed antigens contribute to ECM.

Plasma IP-10, apoptotic and angiogenic factors associated with fatal cerebral malaria in India.

BACKGROUND: Plasmodium falciparum in a subset of patients can lead to cerebral malaria (CM), a major contributor to malaria-associated mortality. Despite treatment, CM mortality can be as high as 30%, while 10% of survivors of the disease may experience short- and long-term neurological complications. The pathogenesis of CM is mediated by alterations in cytokine and chemokine homeostasis, inflammation as well as vascular injury and repair processes although their roles are not fully understood. The hypothesis for this study is that CM-induced changes in inflammatory, apoptotic and angiogenic factors mediate severity of CM and that their identification will enable development of new prognostic markers and adjunctive therapies for preventing CM mortalities. METHODS: Plasma samples (133) were obtained from healthy controls (HC, 25), mild malaria (MM, 48), cerebral malaria survivors (CMS, 48), and cerebral malaria non-survivors (CMNS, 12) at admission to the hospital in Jabalpur, India. Plasma levels of 30 biomarkers ((IL-1beta, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, Eotaxin, FGF basic protein, G-CSF, GM-CSF, IFN-gamma, IP-10, MCP-1 (MCAF), MIP-1alpha, MIP-1beta, RANTES, TNF-alpha, Fas-ligand (Fas-L), soluble Fas (sFas), soluble TNF receptor 1 (sTNF-R1) and soluble TNF receptor 2 (sTNFR-2), PDGF bb and VEGF)) were simultaneously measured in an initial subset of ten samples from each group. Only those biomarkers which showed significant differences in the pilot analysis were chosen for testing on all remaining samples. The results were then compared between the four groups to determine their role in CM severity. RESULTS: IP-10, sTNF-R2 and sFas were independently associated with increased risk of CM associated mortality. CMNS patients had a significantly lower level of the neuroprotective factor VEGF when compared to other groups (P < 0.0045). The ratios of VEGF to IP-10, sTNF-R2, and sFas distinguished CM survivors from non survivors (P < 0.0001). CONCLUSION: The results suggest that plasma levels of IP-10, sTNF-R2 and sFas may be potential biomarkers of CM severity and mortality. VEGF was found to be protective against CM associated mortality and may be considered for adjunctive therapy to improve the treatment outcome in CM patients.

High levels of erythropoietin are associated with protection against neurological sequelae in African children with cerebral malaria.

Cerebral malaria (CM) in children is associated with a high mortality and long-term neurocognitive sequelae. Both erythropoietin (Epo) and vascular endothelial growth factor (VEGF) have been shown to be neuroprotective. We hypothesized that high plasma and cerebrospinal fluid (CSF) levels of these cytokines would prevent neurological sequelae in children with CM. We measured Epo, VEGF, and tumor necrosis factor in paired samples of plasma and CSF of Kenyan children admitted with CM. Logistic regression models were used to identify risk and protective factors associated with the development of neurological sequelae. Children with CM (n = 124) were categorized into three groups: 76 without sequelae, 32 with sequelae, and 16 who died. Conditional logistic regression analysis matching the 32 patients with CM and neurological sequelae to 64 patients with CM without sequelae stratified for hemoglobin level estimated that plasma Epo (>200 units/liter) was associated with >80% reduction in the risk of developing neurological sequelae [adjusted odds ratio (OR) 0.18; 95% C.I. 0.05-0.93; P = 0.041]. Admission with profound coma (adjusted OR 5.47; 95% C.I. 1.45-20.67; P = 0.012) and convulsions after admission (adjusted OR 16.35; 95% C.I. 2.94-90.79; P = 0.001) were also independently associated with neurological sequelae. High levels of Epo were associated with reduced risk of neurological sequelae in children with CM. The age-dependent Epo response to anemia and the age-dependent protective effect may influence the clinical epidemiology of CM. These data support further study of Epo as an adjuvant therapy in CM.

Cerebrospinal fluid and serum biomarkers of cerebral malaria mortality in Ghanaian children.

BACKGROUND: Plasmodium falciparum can cause a diffuse encephalopathy known as cerebral malaria (CM), a major contributor to malaria associated mortality. Despite treatment, mortality due to CM can be as high as 30% while 10% of survivors of the disease may experience short- and long-term neurological complications. The pathogenesis of CM and other forms of severe malaria is multi-factorial and appear to involve cytokine and chemokine homeostasis, inflammation and vascular injury/repair. Identification of prognostic markers that can predict CM severity will enable development of better intervention. METHODS: Postmortem serum and cerebrospinal fluid (CSF) samples were obtained within 2-4 hours of death in Ghanaian children dying of CM, severe malarial anemia (SMA), and non-malarial (NM) causes. Serum and CSF levels of 36 different biomarkers (IL-1beta, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, Eotaxin, FGF basic protein, CRP, G-CSF, GM-CSF, IFN-gamma, TNF-alpha, IP-10, MCP-1 (MCAF), MIP-1alpha, MIP-1beta, RANTES, SDF-1alpha, CXCL11 (I-TAC), Fas-ligand [Fas-L], soluble Fas [sFas], sTNF-R1 (p55), sTNF-R2 (p75), MMP-9, TGF-beta1, PDGF bb and VEGF) were measured and the results compared between the 3 groups. RESULTS: After Bonferroni adjustment for other biomarkers, IP-10 was the only serum biomarker independently associated with CM mortality when compared to SMA and NM deaths. Eight CSF biomarkers (IL-1ra, IL-8, IP-10, PDGFbb, MIP-1beta, Fas-L, sTNF-R1, and sTNF-R2) were significantly elevated in CM mortality group when compared to SMA and NM deaths. Additionally, CSF IP-10/PDGFbb median ratio was statistically significantly higher in the CM group compared to SMA and NM groups. CONCLUSION: The parasite-induced local cerebral dysregulation in the production of IP-10, 1L-8, MIP-1beta, PDGFbb, IL-1ra, Fas-L, sTNF-R1, and sTNF-R2 may be involved in CM neuropathology, and their immunoassay may have potential utility in predicting mortality in CM.

Low levels of RANTES are associated with mortality in children with cerebral malaria.

BACKGROUND: In children with cerebral malaria (CM), serum chemokine levels and associated morbidity and mortality have not been characterized. METHODS: Serum levels of the cytokines interleukin (IL)-1 beta , IL-6, IL-10, interferon (IFN)-gamma, and tumor necrosis factor-alpha and the chemokines macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and regulated upon activation, normal T cell expressed and secreted (RANTES) were measured in Ugandan children with CM, in children with uncomplicated malaria (UM), and in healthy children from the community, as control subjects (CCs). RESULTS: Children with CM had lower levels of RANTES and higher levels of all other cytokines and chemokines than CCs (all P<.0001), and they had lower levels of RANTES (P=.004) and higher levels of IL-10 (P=.003), IFN-gamma (P=.007), and IL-1 beta (P=.05) than children with UM. Children with CM who died had lower levels of RANTES (P=.006) and higher of levels of IL-6 (P=.006), IL-10 (P=.01), IFN-gamma (P=.03), and MIP-1 beta (P=.008) than children who survived. After adjustment for other cytokine and chemokine levels, only low levels of RANTES were independently associated with mortality (P=.016). Levels of RANTES correlated with platelet count but were associated with mortality independently of platelet count. CONCLUSIONS: The serum cytokine and chemokine profile of children who die of CM is similar to that of individuals who die of sepsis. Levels of RANTES are significantly lower in children with CM, and very low levels of RANTES are associated with mortality, independently of other cytokine and chemokine levels.

A review of the quality of randomized clinical trials of adjunctive therapy for the treatment of cerebral malaria.

BACKGROUND: Randomized controlled clinical trials (RCTs) of adjunctive treatment to reduce the high-mortality associated with cerebral malaria (CM) have so far failed to show any benefit. This may be due in part to improperly designed and/or conducted trials. Therefore a systematic review of quality of RCTs for the treatment of CM with mortality as either primary or secondary outcome published between 1980 and 2000, was conducted. METHODS: RCTs from the peer-reviewed literature using electronic searches. Methodological quality was assessed using an individual component approach (adequacy of concealment of allocation schedule, generation of allocation sequence, double blinding and analysis of participant as randomized). Sample sizes were recalculated for the ability of reviewed trials to detect 25% and 50% reductions in mortality. RESULTS: Nine trials satisfied the inclusion criteria and were reviewed. Only two had sufficient power to detect a 50% reduction in mortality, and none could detect a 25% reduction. All the trials had inadequate methodological quality in one or more of the components, although in two trials these deficiencies were few. CONCLUSION: There is a need for researchers and donors to ensure proper planning and implementation of RCTs in developing countries. In CM, demonstration of worthwhile reduction in mortality by a single intervention will require a large number of subjects, which a single centre may not be able to recruit.

High-level cerebellar expression of cytokines and adhesion molecules in fatal, paediatric, cerebral malaria.

Although the roles played by systemic tumour necrosis factor (TNF) and interleukin 1beta (IL-1beta), and their upregulation of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and E-selectin, in the pathogenesis of human cerebral malaria (CM) are well established, the role of local cytokine release, in the brain, remains unclear. Immunohistochemistry was therefore used to compare the expression of ICAM-1, VCAM-1, E-selectin, IL-1beta, TNF and transforming growth factor beta (TGF-beta) at light-microscope level, in cryostat sections of cerebral, cerebellar and brainstem tissues collected, post-mortem, from Ghanaian children. Among the 21 children investigated were 10 cases of CM, five of severe malarial anemia (SMA), one of purulent bacterial meningitis (PBM), two of non-central-nervous-system infection (NCNSI) and three children who had no infection (NI) when they died. Parasitised erythrocytes were detected in all of the sections from the cases of fatal malaria (CM and SMA), and sequestered leucocytes were present in most of the sections from the CM cases (but none of the sections from the SMA cases). Significantly elevated vascular expression of all three adhesion molecules investigated was detected in the brains of the 15 cases of fatal malaria and one of the cases of NCNSI (a child with Salmonella septicaemia), and in the malaria cases this showed highly significant co-localization with the areas of erythrocyte sequestration. In terms of the levels of expression of ICAM-1, VCAM-1 and E-selectin, there were, however, negligible differences between the CM and SMA cases. Although TGF-beta showed intravascular and perivascular distribution in all the subjects, its expression was most intense in the PBM case and the CM group. Only in the sections from the PBM and CM cases did TNF and IL-1beta show prominent brain parenchymal staining, in addition to the intravascular and perivascular staining seen in all subjects. The highest observed expression of each of the six antigens studied was in the cerebellar sections of the malaria cases. Endothelial activation in the brain therefore appears to be a feature of fatal malaria and Salmonella sepsis, and in cases of fatal malaria is closely associated with leucocyte sequestration. In the present study, IL-1beta and TNF were only up-regulated in the brains of children with neurodegenerative lesions, whereas TGF-beta was present in all cases.

Angiogenic proteins in brains of patients who died with cerebral malaria.

In cerebral malaria (CM), microvascular activation accompanies blood-brain barrier dysfunction which in turn represents the pathophysiological basis of neurological impairments in affected patients. To dissect the molecular basis of this process, we analyzed localization of proangiogenic vascular endothelial growth factor (VEGF), its receptor vascular endothelial growth factor receptor-1 (VEGFR-1, Flt-1), of downstream VEGF effectors matrix-metalloproteinase-1 (MMP-1) and connective tissue growth factor (CTGF), and of VEGF-interacting antiangiogenic thrombospondin-1 and -independent angiostatin in brains of patients who died with CM and controls by immunohistochemistry and Western blotting experiments. Most prominently, we detected more VEGF(+) astrocytes in CM patients and deposition of Flt-1 in Dürck's granulomas. MMP-1 and thrombospondin-1 accumulated in macrophages/microglial cells in Dürck's granulomas. In one CM patient, massive amounts of CTGF were detected as perivascular paracellular deposits. Angiostatin was observed in the serum of 2/7 control but in no CM patients. These data demonstrate the activation of the proangiogenic VEGF signaling cascade in patients with CM, probably reflecting compensatory mechanisms of general and focal brain hypoxia observed in these patients.

Plasma glucose and tumour necrosis factor-alpha in adult patients with severe falciparum malaria.

Plasma glucose was assessed in 81 patients with severe falciparum malaria at the time of presentation along with tumour necrosis factor-alpha (TNF-alpha). The lowest plasma glucose value was 3.38 mmol/l and none of the patients had hypoglycaemia at admission. Plasma glucose values were not significantly lower in those with multiple organ dysfunction (MOD) than in patients with single organ dysfunction (cerebral malaria only) and in those who died compared with patients who survived. Conversely, TNF-alpha showed a good correlation with depth of coma and was significantly higher in patients who had MOD and those who died. There was no correlation between plasma glucose and TNF-alpha values.

Accumulation of endostatin/collagenXVIII in brains of patients who died with cerebral malaria.

Endostatin is a 20 kDa C-terminal fragment of collagenXVIII that, when added exogenously, inhibits angiogenesis by inducing apoptosis of endothelial cells. In cerebral malaria (CM), blood-brain barrier dysfunction is a hallmark alteration in the formation of edema, inflammation, hemorrhage and Dürck's granulomas that are thought to represent the histopathological basis of neurological impairments observed in CM patients. We now analyzed endostatin/collagenXVIII expression in brains of seven patients who died with CM and in seven control patients by immunohistochemistry double-labeling experiments. Endostatin/collagenXVIII immunoreactive macrophages/microglial cells accumulated predominantly in Dürck's granulomas. Some immunoreactivity was observed in macrophages located in cerebral capillaries with deposition of malarial pigment and sequestration, but almost no immunoreactivity was detected in ring hemorrhages. Focal accumulation of endostatin/collagenXVIII in granulomas but not in ring hemorrhages of CM brains suggests a novel process that is involved in the destruction of endothelial cells at the time of Dürck's granuloma formation.

Role of the tumor necrosis factor receptor 2 (TNFR2) in cerebral malaria in mice.

Infection of susceptible mice with Plasmodium berghei Anka leads to a syndrome of severe or cerebral malaria. Tumor necrosis factor (TNF) contributes to this syndrome, apparently by acting on its receptor 2 (TNFR2) because TNFR1-/- are susceptible, whereas TNFR2-/- mice are resistant. In this work, we confirmed the essential role of the TNFR2 in cerebral malaria because 6 to 8 days after Plasmodium berghei Anka infection, hypothermia, coma, and death were observed in +/+ or TNFR1-/-, but never in TNFR2-/-, mice. TNF production, evaluated by the serum levels or the mRNA levels in the brain, spleen or lung, was similar in +/+, TNFR1-/-, or TNFR2-/- mice. Macrophage or parasitized red blood cell sequestration in brain or lung was similar in TNFR1-/- and TNFR2-/- mice. Accordingly, up-regulation of CD54 or CD40 in brain or lung was also similar in TNFR1-/- or TNFR2-/- mice. Platelet loss, manifested by thrombocytopenia and the presence of microparticles in plasma, was similar in TNFR1-/- or TNFR2-/- mice. Breakdown of the blood-brain barrier, detected by the diffusion of tracers, was attenuated in both TNFR1-/- and TNFR2-/-, compared with +/+, mice. Endothelial cells from brain capillaries, examined by transmission electron microscopy, were similar in infected TNFR1-/- or TNFR2-/- mice, whereas the basement membrane was enlarged in TNFR1-/- mice. Hypothermic mice were also hyperglycemic, and this was evident in +/+ and TNFR1-/-, but not in TNFR2-/-, mice. In addition, infected +/+ and TNFR1-/- mice became insulin resistant, while in contrast TNFR2-/- became extremely insulin sensitive. This study supports the possibility that coma and death are mediated not by cell sequestration or breakdown of vascular permeability, similar in TNFR1-/- or TNFR2-/- mice, but by metabolic disturbances selectively mediated by the TNFR2.

Mitochondrial anomalies are associated with the induction of intrinsic cell death proteins-Bcl(2), Bax, cytochrome-c and p53 in mice brain during experimental fatal murine cerebral malaria.

The levels of apoptosis associated proteins Bcl(2), Bax, cytochrome-c and p53 was investigated in mice cerebral cortex and cerebellum, using an experimental model of fatal murine cerebral malaria (FMCM). Owing to the activation of events central to mitochondrial dysfunctions, we monitored the structural integrity of mitochondria in cerebral malaria (CM) infected brain tissue by transmission EM (TEM) studies. Western blot analysis revealed the induction of Bcl(2), Bax, cytochrome-c and p53 in both cortex and cerebellum. The TEM studies revealed extensive vacuolation and swelling of mitochondria in infected brain suggestive of a late stage of degeneration. Our results underscore the activation of an intrinsic cell death pathway as evinced by the induction of mitochondria associated apoptotic proteins Bcl(2), Bax and cytochrome-c and further envisages the induction of p53 as a possible continuation of the post receptor signaling events associated with tumor necrosis factor induction following inflammatory responses during CM. These findings may be crucial to mitochondrial dysfunctions underlying the pathology of FMCM.