Metabolite profiles of medulloblastoma for rapid and non-invasive detection of molecular disease groups.

BACKGROUND: The malignant childhood brain tumour, medulloblastoma, is classified clinically into molecular groups which guide therapy. DNA-methylation profiling is the current classification 'gold-standard', typically delivered 3-4 weeks post-surgery. Pre-surgery non-invasive diagnostics thus offer significant potential to improve early diagnosis and clinical management. Here, we determine tumour metabolite profiles of the four medulloblastoma groups, assess their diagnostic utility using tumour tissue and potential for non-invasive diagnosis using in vivo magnetic resonance spectroscopy (MRS). METHODS: Metabolite profiles were acquired by high-resolution magic-angle spinning NMR spectroscopy (MAS) from 86 medulloblastomas (from 59 male and 27 female patients), previously classified by DNA-methylation array (WNT (n = 9), SHH (n = 22), Group3 (n = 21), Group4 (n = 34)); RNA-seq data was available for sixty. Unsupervised class-discovery was performed and a support vector machine (SVM) constructed to assess diagnostic performance. The SVM classifier was adapted to use only metabolites (n = 10) routinely quantified from in vivo MRS data, and re-tested. Glutamate was assessed as a predictor of overall survival. FINDINGS: Group-specific metabolite profiles were identified; tumours clustered with good concordance to their reference molecular group (93%). GABA was only detected in WNT, taurine was low in SHH and lipids were high in Group3. The tissue-based metabolite SVM classifier had a cross-validated accuracy of 89% (100% for WNT) and, adapted to use metabolites routinely quantified in vivo, gave a combined classification accuracy of 90% for SHH, Group3 and Group4. Glutamate predicted survival after incorporating known risk-factors (HR = 3.39, 95% CI 1.4-8.1, p = 0.025). INTERPRETATION: Tissue metabolite profiles characterise medulloblastoma molecular groups. Their combination with machine learning can aid rapid diagnosis from tissue and potentially in vivo. Specific metabolites provide important information; GABA identifying WNT and glutamate conferring poor prognosis. FUNDING: Children with Cancer UK, Cancer Research UK, Children's Cancer North and a Newcastle University PhD studentship.

OPA1 disease-causing mutants have domain-specific effects on mitochondrial ultrastructure and fusion.

Inner mitochondrial membrane fusion and cristae shape depend on optic atrophy protein 1, OPA1. Mutations in OPA1 lead to autosomal dominant optic atrophy (ADOA), an important cause of inherited blindness. The Guanosin Triphosphatase (GTPase) and GTPase effector domains (GEDs) of OPA1 are essential for mitochondrial fusion; yet, their specific roles remain elusive. Intriguingly, patients carrying OPA1 GTPase mutations have a higher risk of developing more severe multisystemic symptoms in addition to optic atrophy, suggesting pathogenic contributions for the GTPase and GED domains, respectively. We studied OPA1 GTPase and GED mutations to understand their domain-specific contribution to protein function by analyzing patient-derived cells and gain-of-function paradigms. Mitochondria from OPA1 GTPase (c.870+5G>A and c.889C>T) and GED (c.2713C>T and c.2818+5G>A) mutants display distinct aberrant cristae ultrastructure. While all OPA1 mutants inhibited mitochondrial fusion, some GTPase mutants resulted in elongated mitochondria, suggesting fission inhibition. We show that the GED is dispensable for fusion and OPA1 oligomer formation but necessary for GTPase activity. Finally, splicing defect mutants displayed a posttranslational haploinsufficiency-like phenotype but retained domain-specific dysfunctions. Thus, OPA1 domain-specific mutants result in distinct impairments in mitochondrial dynamics, providing insight into OPA1 function and its contribution to ADOA pathogenesis and severity.

Retinal pigment epithelium extracellular vesicles are potent inducers of age-related macular degeneration disease phenotype in the outer retina.

Age-related macular degeneration (AMD) is a leading cause of blindness. Vision loss is caused by the retinal pigment epithelium (RPE) and photoreceptors atrophy and/or retinal and choroidal angiogenesis. Here we use AMD patient-specific RPE cells with the Complement Factor H Y402H high-risk polymorphism to perform a comprehensive analysis of extracellular vesicles (EVs), their cargo and role in disease pathology. We show that AMD RPE is characterised by enhanced polarised EV secretion. Multi-omics analyses demonstrate that AMD RPE EVs carry RNA, proteins and lipids, which mediate key AMD features including oxidative stress, cytoskeletal dysfunction, angiogenesis and drusen accumulation. Moreover, AMD RPE EVs induce amyloid fibril formation, revealing their role in drusen formation. We demonstrate that exposure of control RPE to AMD RPE apical EVs leads to the acquisition of AMD features such as stress vacuoles, cytoskeletal destabilization and abnormalities in the morphology of the nucleus. Retinal organoid treatment with apical AMD RPE EVs leads to disrupted neuroepithelium and the appearance of cytoprotective alpha B crystallin immunopositive cells, with some co-expressing retinal progenitor cell markers Pax6/Vsx2, suggesting injury-induced regenerative pathways activation. These findings indicate that AMD RPE EVs are potent inducers of AMD phenotype in the neighbouring RPE and retinal cells.

WFS1-Associated Optic Neuropathy: Genotype-Phenotype Correlations and Disease Progression.

OBJECTIVE: To evaluate the pattern of vision loss and genotype-phenotype correlations in WFS1-associated optic neuropathy (WON). DESIGN: Multicenter cohort study. METHODS: The study involved 37 patients with WON carrying pathogenic or candidate pathogenic WFS1 variants. Genetic and clinical data were retrieved from the medical records. Thirteen patients underwent additional comprehensive ophthalmologic assessment. Deep phenotyping involved visual electrophysiology and advanced psychophysical testing with a complementary metabolomic study. MAIN OUTCOME MEASURES: WFS1 variants, functional and structural optic nerve and retinal parameters, and metabolomic profile. RESULTS: Twenty-two recessive and 5 dominant WFS1 variants were identified. Four variants were novel. All WFS1 variants caused loss of macular retinal ganglion cells (RGCs) as assessed by optical coherence tomography (OCT) and visual electrophysiology. Advanced psychophysical testing indicated involvement of the major RGC subpopulations. Modeling of vision loss showed an accelerated rate of deterioration with increasing age. Dominant WFS1 variants were associated with abnormal reflectivity of the outer plexiform layer (OPL) on OCT imaging. The dominant variants tended to cause less severe vision loss compared with recessive WFS1 variants, which resulted in more variable phenotypes ranging from isolated WON to severe multisystem disease depending on the WFS1 alleles. The metabolomic profile included markers seen in other neurodegenerative diseases and type 1 diabetes mellitus. CONCLUSIONS: WFS1 variants result in heterogenous phenotypes influenced by the mode of inheritance and the disease-causing alleles. Biallelic WFS1 variants cause more variable, but generally more severe, vision and RGC loss compared with heterozygous variants. Abnormal cleftlike lamination of the OPL is a distinctive OCT feature that strongly points toward dominant WON.

Altered ceramide metabolism is a feature in the extracellular vesicle-mediated spread of alpha-synuclein in Lewy body disorders.

Mutations in glucocerebrosidase (GBA) are the most prevalent genetic risk factor for Lewy body disorders (LBD)-collectively Parkinson's disease, Parkinson's disease dementia and dementia with Lewy bodies. Despite this genetic association, it remains unclear how GBA mutations increase susceptibility to develop LBD. We investigated relationships between LBD-specific glucocerebrosidase deficits, GBA-related pathways, and α-synuclein levels in brain tissue from LBD and controls, with and without GBA mutations. We show that LBD is characterised by altered sphingolipid metabolism with prominent elevation of ceramide species, regardless of GBA mutations. Since extracellular vesicles (EV) could be involved in LBD pathogenesis by spreading disease-linked lipids and proteins, we investigated EV derived from post-mortem cerebrospinal fluid (CSF) and brain tissue from GBA mutation carriers and non-carriers. EV purified from LBD CSF and frontal cortex were heavily loaded with ceramides and neurodegeneration-linked proteins including alpha-synuclein and tau. Our in vitro studies demonstrate that LBD EV constitute a "pathological package" capable of inducing aggregation of wild-type alpha-synuclein, mediated through a combination of alpha-synuclein-ceramide interaction and the presence of pathological forms of alpha-synuclein. Together, our findings indicate that abnormalities in ceramide metabolism are a feature of LBD, constituting a promising source of biomarkers, and that GBA mutations likely accelerate the pathological process occurring in sporadic LBD through endolysosomal deficiency.

Depleted circulatory complement-lysis inhibitor (CLI) in childhood cerebral malaria returns to normal with convalescence.

BACKGROUND: Cerebral malaria (CM), is a life-threatening childhood malaria syndrome with high mortality. CM is associated with impaired consciousness and neurological damage. It is not fully understood, as yet, why some children develop CM. Presented here is an observation from longitudinal studies on CM in a paediatric cohort of children from a large, densely-populated and malaria holoendemic, sub-Saharan, West African metropolis. METHODS: Plasma samples were collected from a cohort of children with CM, severe malarial anaemia (SMA), uncomplicated malaria (UM), non-malaria positive healthy community controls (CC), and coma and anemic patients without malaria, as disease controls (DC). Proteomic two-dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry were used in a discovery cohort to identify plasma proteins that might be discriminatory among these clinical groups. The circulatory levels of identified proteins of interest were quantified by ELISA in a prospective validation cohort. RESULTS: The proteome analysis revealed differential abundance of circulatory complement-lysis inhibitor (CLI), also known as Clusterin (CLU). CLI circulatory level was low at hospital admission in all children presenting with CM and recovered to normal level during convalescence (p < 0.0001). At acute onset, circulatory level of CLI in the CM group significantly discriminates CM from the UM, SMA, DC and CC groups. CONCLUSIONS: The CLI circulatory level is low in all patients in the CM group at admission, but recovers through convalescence. The level of CLI at acute onset may be a specific discriminatory marker of CM. This work suggests that CLI may play a role in the pathophysiology of CM and may be useful in the diagnosis and follow-up of children presenting with CM.

Monoamine oxidase-A promotes protective autophagy in human SH-SY5Y neuroblastoma cells through Bcl-2 phosphorylation.

Monoamine oxidases (MAOs) are located on the outer mitochondrial membrane and are drug targets for the treatment of neurological disorders. MAOs control the levels of neurotransmitters in the brain via oxidative deamination and contribute to reactive oxygen species (ROS) generation through their catalytic by-product H2O2. Increased ROS levels may modulate mitochondrial function and mitochondrial dysfunction is implicated in a vast array of disorders. However, the downstream effects of MAO-A mediated ROS production in a neuronal model has not been previously investigated. In this study, using MAO-A overexpressing neuroblastoma cells, we demonstrate that higher levels of MAO-A protein/activity results in increased basal ROS levels with associated increase in protein oxidation. Increased MAO-A levels result in increased Lysine-63 linked ubiquitination of mitochondrial proteins and promotes autophagy through Bcl-2 phosphorylation. Furthermore, ROS generated locally on the mitochondrial outer membrane by MAO-A promotes phosphorylation of dynamin-1-like protein, leading to mitochondrial fragmentation and clearance without complete loss of mitochondrial membrane potential. Cellular ATP levels are maintained following MAO-A overexpression and complex IV activity/protein levels increased, revealing a close relationship between MAO-A levels and mitochondrial function. Finally, the downstream effects of increased MAO-A levels are dependent on the availability of amine substrates and in the presence of exogenous substrate, cell viability is dramatically reduced. This study shows for the first time that MAO-A generated ROS is involved in quality control signalling, and increase in MAO-A protein levels leads to a protective cellular response in order to mediate removal of damaged macromolecules/organelles, but substrate availability may ultimately determine cell fate. The latter is particularly important in conditions such as Parkinson's disease, where a dopamine precursor is used to treat disease symptoms and highlights that the fate of MAO-A containing dopaminergic neurons may depend on both MAO-A levels and catecholamine substrate availability.

Low plasma haptoglobin is a risk factor for life-threatening childhood severe malarial anemia and not an exclusive consequence of hemolysis.

Severe Malarial Anemia (SMA), a life-threatening childhood Plasmodium falciparum malaria syndrome requiring urgent blood transfusion, exhibits inflammatory and hemolytic pathology. Differentiating between hypo-haptoglobinemia due to hemolysis or that of genetic origin is key to understand SMA pathogenesis. We hypothesized that while malaria-induced hypo-haptoglobinemia should reverse at recovery, that of genetic etiology should not. We carried-out a case-control study of children living under hyper-endemic holoendemic malaria burden in the sub-Saharan metropolis of Ibadan, Nigeria. We show that hypo-haptoglobinemia is a risk factor for childhood SMA and not solely due to intravascular hemolysis from underlying schizogony. In children presenting with SMA, hypo-haptoglobinemia remains through convalescence to recovery suggesting a genetic cause. We identified a haptoglobin gene variant, rs12162087 (g.-1203G > A, frequency = 0.67), to be associated with plasma haptoglobin levels (p = 8.5 × 10-6). The Homo-Var:(AA) is associated with high plasma haptoglobin while the reference Homo-Ref:(GG) is associated with hypo-haptoglobinemia (p = 2.3 × 10-6). The variant is associated with SMA, with the most support for a risk effect for Homo-Ref genotype. Our insights on regulatory haptoglobin genotypes and hypo-haptoglobinemia suggest that haptoglobin screening could be part of risk-assessment algorithms to prevent rapid disease progression towards SMA in regions with no-access to urgent blood transfusion where SMA accounts for high childhood mortality rates.

Clonal expansion of mtDNA deletions: different disease models assessed by digital droplet PCR in single muscle cells.

Deletions in mitochondrial DNA (mtDNA) are an important cause of human disease and their accumulation has been implicated in the ageing process. As mtDNA is a high copy number genome, the coexistence of deleted and wild-type mtDNA molecules within a single cell defines heteroplasmy. When deleted mtDNA molecules, driven by intracellular clonal expansion, reach a sufficiently high level, a biochemical defect emerges, contributing to the appearance and progression of clinical pathology. Consequently, it is relevant to determine the heteroplasmy levels within individual cells to understand the mechanism of clonal expansion. Heteroplasmy is reflected in a mosaic distribution of cytochrome c oxidase (COX)-deficient muscle fibers. We applied droplet digital PCR (ddPCR) to single muscle fibers collected by laser-capture microdissection (LCM) from muscle biopsies of patients with different paradigms of mitochondrial disease, characterized by the accumulation of single or multiple mtDNA deletions. By combining these two sensitive approaches, ddPCR and LCM, we document different models of clonal expansion in patients with single and multiple mtDNA deletions, implicating different mechanisms and time points for the development of COX deficiency in these molecularly distinct mitochondrial cytopathies.

metabolic profiling of Parkinson's disease and mild cognitive impairment.

BACKGROUND: Early diagnosis of Parkinson's disease and mild cognitive impairment is important to enable prompt treatment and improve patient welfare, yet no standard diagnostic test is available. Metabolomics is a powerful tool used to elucidate disease mechanisms and identify potential biomarkers. OBJECTIVES: The objective of this study was to use metabolic profiling to understand the pathoetiology of Parkinson's disease and to identify potential disease biomarkers. METHODS: This study compared the serological metabolomic profiles of early-stage Parkinson's patients (diagnosed < 12 months) to asymptomatic matched controls using an established array based detection system (DiscoveryHD4™, Metabolon, UK), correlating metabolite levels to clinical measurements of cognitive impairment. RESULTS: A total of 1434 serological metabolites were assessed in early-stage Parkinson's disease cases (n = 41) and asymptomatic matched controls (n = 40). Post-quality control, statistical analysis identified n = 20 metabolites, predominantly metabolites of the fatty acid oxidation pathway, associated with Parkinson's disease and mild cognitive impairment. Receiver operator curve assessment confirmed that the nine fatty acid oxidation metabolites had good predictive accuracy (area under curve = 0.857) for early-stage Parkinson's disease and mild cognitive impairment (area under curve = 0.759). CONCLUSIONS: Our study indicates that fatty acid oxidation may be an important component in the pathophysiology of Parkinson's disease and may have potential as a diagnostic biomarker for disease onset and mild cognitive impairment. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

A novel CISD2 mutation associated with a classical Wolfram syndrome phenotype alters Ca2+ homeostasis and ER-mitochondria interactions.

Wolfram syndrome (WS) is a progressive neurodegenerative disease characterized by early-onset optic atrophy and diabetes mellitus, which can be associated with more extensive central nervous system and endocrine complications. The majority of patients harbour pathogenic WFS1 mutations, but recessive mutations in a second gene, CISD2, have been described in a small number of families with Wolfram syndrome type 2 (WFS2). The defining diagnostic criteria for WFS2 also consist of optic atrophy and diabetes mellitus, but unlike WFS1, this phenotypic subgroup has been associated with peptic ulcer disease and an increased bleeding tendency. Here, we report on a novel homozygous CISD2 mutation (c.215A > G; p.Asn72Ser) in a Moroccan patient with an overlapping phenotype suggesting that Wolfram syndrome type 1 and type 2 form a continuous clinical spectrum with genetic heterogeneity. The present study provides strong evidence that this particular CISD2 mutation disturbs cellular Ca2+ homeostasis with enhanced Ca2+ flux from the ER to mitochondria and cytosolic Ca2+ abnormalities in patient-derived fibroblasts. This Ca2+ dysregulation was associated with increased ER-mitochondria contact, a swollen ER lumen and a hyperfused mitochondrial network in the absence of overt ER stress. Although there was no marked alteration in mitochondrial bioenergetics under basal conditions, culture of patient-derived fibroblasts in glucose-free galactose medium revealed a respiratory chain defect in complexes I and II, and a trend towards decreased ATP levels. Our results provide important novel insight into the potential disease mechanisms underlying the neurodegenerative consequences of CISD2 mutations and the subsequent development of multisystemic disease.

A Functional IL22 Polymorphism (rs2227473) Is Associated with Predisposition to Childhood Cerebral Malaria.

Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection. This encephalopathy is characterized by coma and is thought to result from mechanical microvessel obstruction and an excessive activation of immune cells leading to pathological inflammation and blood-brain barrier alterations. IL-22 contributes to both chronic inflammatory and infectious diseases, and may have protective or pathogenic effects, depending on the tissue and disease state. We evaluated whether polymorphisms (n = 46) of IL22 and IL22RA2 were associated with CM in children from Nigeria and Mali. Two SNPs of IL22, rs1012356 (P = 0.016, OR = 2.12) and rs2227476 (P = 0.007, OR = 2.08) were independently associated with CM in a sample of 115 Nigerian children with CM and 160 controls. The association with rs2227476 (P = 0.01) was replicated in 240 nuclear families with one affected child from Mali. SNP rs2227473, in linkage disequilibrium with rs2227476, was also associated with CM in the combined cohort for these two populations, (P = 0.004, OR = 1.55). SNP rs2227473 is located within a putative binding site for the aryl hydrocarbon receptor, a master regulator of IL-22 production. Individuals carrying the aggravating T allele of rs2227473 produced significantly more IL-22 than those without this allele. Overall, these findings suggest that IL-22 is involved in the pathogenesis of CM.

Evaluating the therapeutic potential of idebenone and related quinone analogues in Leber hereditary optic neuropathy.

Leber hereditary optic neuropathy (LHON) is an important cause of mitochondrial blindness among young adults. In this study, we investigated the potential of four quinone analogues (CoQ1, CoQ10, decylubiquinone and idebenone) in compensating for the deleterious effect of the m.11778G>A mitochondrial DNA mutation. The LHON fibroblast cell lines tested exhibited reduced cell growth, impaired mitochondrial bioenergetics and elevated levels of reactive oxygen species (ROS). Idebenone increased ATP production and reduced ROS levels, but the effect was partial and cell-specific. The remaining quinone analogues had variable effects and a negative impact on certain mitochondrial parameters was observed in some cell lines.

A neurodegenerative perspective on mitochondrial optic neuropathies.

Mitochondrial optic neuropathies constitute an important cause of chronic visual morbidity and registrable blindness in both the paediatric and adult population. It is a genetically heterogeneous group of disorders caused by both mitochondrial DNA (mtDNA) mutations and a growing list of nuclear genetic defects that invariably affect a critical component of the mitochondrial machinery. The two classical paradigms are Leber hereditary optic neuropathy (LHON), which is a primary mtDNA disorder, and autosomal dominant optic atrophy (DOA) secondary to pathogenic mutations within the nuclear gene OPA1 that encodes for a mitochondrial inner membrane protein. The defining neuropathological feature is the preferential loss of retinal ganglion cells (RGCs) within the inner retina but, rather strikingly, the smaller calibre RGCs that constitute the papillomacular bundle are particularly vulnerable, whereas melanopsin-containing RGCs are relatively spared. Although the majority of patients with LHON and DOA will present with isolated optic nerve involvement, some individuals will also develop additional neurological complications pointing towards a greater vulnerability of the central nervous system (CNS) in susceptible mutation carriers. These so-called "plus" phenotypes are mechanistically important as they put the loss of RGCs within the broader perspective of neuronal loss and mitochondrial dysfunction, highlighting common pathways that could be modulated to halt progressive neurodegeneration in other related CNS disorders. The management of patients with mitochondrial optic neuropathies still remains largely supportive, but the development of effective disease-modifying treatments is now within tantalising reach helped by major advances in drug discovery and delivery, and targeted genetic manipulation.

Fatal infantile mitochondrial encephalomyopathy, hypertrophic cardiomyopathy and optic atrophy associated with a homozygous OPA1 mutation.

BACKGROUND: Infantile-onset encephalopathy and hypertrophic cardiomyopathy caused by mitochondrial oxidative phosphorylation defects are genetically heterogeneous with defects involving both the mitochondrial and nuclear genomes. OBJECTIVE: To identify the causative genetic defect in two sisters presenting with lethal infantile encephalopathy, hypertrophic cardiomyopathy and optic atrophy. METHODS: We describe a comprehensive clinical, biochemical and molecular genetic investigation of two affected siblings from a consanguineous family. Molecular genetic analysis was done by a combined approach involving genome-wide autozygosity mapping and next-generation exome sequencing. Biochemical analysis was done by enzymatic analysis and Western blot. Evidence for mitochondrial DNA (mtDNA) instability was investigated using long-range and real-time PCR assays. Mitochondrial cristae morphology was assessed with transmission electron microscopy. RESULTS: Both affected sisters presented with a similar cluster of neurodevelopmental deficits marked by failure to thrive, generalised neuromuscular weakness and optic atrophy. The disease progression was ultimately fatal with severe encephalopathy and hypertrophic cardiomyopathy. Mitochondrial respiratory chain complex activities were globally decreased in skeletal muscle biopsies. They were found to be homozygous for a novel c.1601T>G (p.Leu534Arg) mutation in the OPA1 gene, which resulted in a marked loss of steady-state levels of the native OPA1 protein. We observed severe mtDNA depletion in DNA extracted from the patients' muscle biopsies. Mitochondrial morphology was consistent with abnormal mitochondrial membrane fusion. CONCLUSIONS: We have established, for the first time, a causal link between a pathogenic homozygous OPA1 mutation and human disease. The fatal multisystemic manifestations observed further extend the complex phenotype associated with pathogenic OPA1 mutations, in particular the previously unreported association with hypertrophic cardiomyopathy. Our findings further emphasise the vital role played by OPA1 in mitochondrial biogenesis and mtDNA maintenance.

The IL17F and IL17RA Genetic Variants Increase Risk of Cerebral Malaria in Two African Populations.

Cerebral malaria (CM) is a neurological complication of infection with Plasmodium falciparum that is partly caused by cytokine-mediated inflammation. It is not known whether interleukin-17 (IL-17) cytokines, which regulate inflammation, control the development of CM. To evaluate the involvement of IL-17 cytokines in CM, we analyzed 46 common polymorphisms in IL17A, IL17F, and IL17RA (which encodes the common receptor chain of the members of the IL-17 family) in two independent African populations. A case-control study involving 115 Nigerian children with CM and 160 controls from the community (CC) showed that IL17F reference single nucleotide polymorphism (SNP) 6913472 (rs6913472) (P = 0.004; odds ratio [OR] = 3.12), IL17F rs4715291 (P = 0.004; OR = 2.82), IL17RA rs12159217 (P = 0.01; OR = 2.27), and IL17RA rs41396547 (P = 0.026; OR = 3.15) were independently associated with CM. A replication study was performed in 240 nuclear Malian family trios (two parents with one CM child). We replicated the association for 3 SNPs, IL17F rs6913472 (P = 0.03; OR = 1.39), IL17RA rs12159217 (P = 0.01; OR = 1.52), and IL17RA rs41396547 (P = 0.04; OR = 3.50). We also found that one additional SNP, IL17RA rs41433045, in linkage disequilibrium (LD) with rs41396547, was associated with CM in both Nigeria and Mali (P = 0.002; OR = 4.12 in the combined sample). We excluded the possibility that SNPs outside IL17F and IL17RA, in strong LD with the associated SNPs, could account for the observed associations. Furthermore, the results of a functional study indicated that the aggravating GA genotype of IL17F rs6913472 was associated with lower IL-17F concentrations. Our findings show for the first time that IL17F and IL17RA polymorphisms modulate susceptibility to CM and provide evidence that IL-17F protects against CM.

CHCHD10 mutations promote loss of mitochondrial cristae junctions with impaired mitochondrial genome maintenance and inhibition of apoptosis.

CHCHD10-related diseases include mitochondrial DNA instability disorder, frontotemporal dementia-amyotrophic lateral sclerosis (FTD-ALS) clinical spectrum, late-onset spinal motor neuropathy (SMAJ), and Charcot-Marie-Tooth disease type 2 (CMT2). Here, we show that CHCHD10 resides with mitofilin, CHCHD3 and CHCHD6 within the "mitochondrial contact site and cristae organizing system" (MICOS) complex. CHCHD10 mutations lead to MICOS complex disassembly and loss of mitochondrial cristae with a decrease in nucleoid number and nucleoid disorganization. Repair of the mitochondrial genome after oxidative stress is impaired in CHCHD10 mutant fibroblasts and this likely explains the accumulation of deleted mtDNA molecules in patient muscle. CHCHD10 mutant fibroblasts are not defective in the delivery of mitochondria to lysosomes suggesting that impaired mitophagy does not contribute to mtDNA instability. Interestingly, the expression of CHCHD10 mutant alleles inhibits apoptosis by preventing cytochrome c release.

Malaria induces anemia through CD8+ T cell-dependent parasite clearance and erythrocyte removal in the spleen.

UNLABELLED: Severe malarial anemia (SMA) in semi-immune individuals eliminates both infected and uninfected erythrocytes and is a frequent fatal complication. It is proportional not to circulating parasitemia but total parasite mass (sequestered) in the organs. Thus, immune responses that clear parasites in organs may trigger changes leading to anemia. Here, we use an outbred-rat model where increasing parasite removal in the spleen escalated uninfected-erythrocyte removal. Splenic parasite clearance was associated with activated CD8(+) T cells, immunodepletion of which prevented parasite clearance. CD8(+) T cell repletion and concomitant reduction of the parasite load was associated with exacerbated (40 to 60%) hemoglobin loss and changes in properties of uninfected erythrocytes. Together, these data suggest that CD8(+) T cell-dependent parasite clearance causes erythrocyte removal in the spleen and thus anemia. In children infected with the human malaria parasite Plasmodium falciparum, elevation of parasite biomass (not the number of circulating parasites) increased the odds ratio for SMA by 3.5-fold (95% confidence intervals [CI95%], 1.8- to 7.5-fold). CD8(+) T cell expansion/activation independently increased the odds ratio by 2.4-fold (CI95%, 1.0- to 5.7-fold). Concomitant increases in both conferred a 7-fold (CI95%, 1.9- to 27.4-fold)-greater risk for SMA. Together, these data suggest that CD8(+)-dependent parasite clearance may predispose individuals to uninfected-erythrocyte loss and SMA, thus informing severe disease diagnosis and strategies for vaccine development. IMPORTANCE: Malaria is a major global health problem. Severe malaria anemia (SMA) is a complex disease associated with partial immunity. Rapid hemoglobin reductions of 20 to 50% are commonly observed and must be rescued by transfusion (which can carry a risk of HIV acquisition). The causes and risk factors of SMA remain poorly understood. Recent studies suggest that SMA is linked to parasite biomass sequestered in organs. This led us to investigate whether immune mechanisms that clear parasites in organs trigger anemia. In rats, erythropoiesis is largely restricted to the bone marrow, and critical aspects of the spleen expected to be important in anemia are similar to those in humans. Therefore, using a rat model, we show that severe anemia is caused through CD8(+) T cell-dependent parasite clearance and erythrocyte removal in the spleen. CD8 activation may also be a new risk factor for SMA in African children.

Disturbed mitochondrial dynamics and neurodegenerative disorders.

Mitochondria form a highly interconnected tubular network throughout the cell via a dynamic process, with mitochondrial segments fusing and breaking apart continuously. Strong evidence has emerged to implicate disturbed mitochondrial fusion and fission as central pathological components underpinning a number of childhood and adult-onset neurodegenerative disorders. Several proteins that regulate the morphology of the mitochondrial network have been identified, the most widely studied of which are optic atrophy 1 and mitofusin 2. Pathogenic mutations that disrupt these two pro-fusion proteins cause autosomal dominant optic atrophy and axonal Charcot-Marie-Tooth disease type 2A, respectively. These disorders predominantly affect specialized neurons that require precise shuttling of mitochondria over long axonal distances. Considerable insight has also been gained by carefully dissecting the deleterious consequences of imbalances in mitochondrial fusion and fission on respiratory chain function, mitochondrial quality control (mitophagy), and programmed cell death. Interestingly, these cellular processes are also implicated in more-common complex neurodegenerative disorders, such as Alzheimer disease and Parkinson disease, indicating a common pathological thread and a close relationship with mitochondrial structure, function and localization. Understanding how these fundamental processes become disrupted will prove crucial to the development of therapies for the growing number of neurodegenerative disorders linked to disturbed mitochondrial dynamics.