RESUMO
Two-thirds of published patients with anti-leucine rich, glioma inactivated 1 (LGI1) encephalitis develop hippocampal sclerosis (HS). It is likely that this contributes to residual cognitive long-term deficits and the risk of epilepsy. Almost all patients harbor anti-LGI1-immunoglobulin G-(IgG-) subclass 4, which is considered a "benign", non-destructive subclass. In contrast, neuropathological case studies have suggested that the classical complement cascade may contribute to mediotemporal cell death in patients with LGI1 antibodies. IgG subclasses 1, 2, or 3 are required to initiate this cascade. We hypothesized that patients with these anti-LGI1-IgG1/2/3 in addition to IgG4 have a higher risk of developing HS than patients with anti-LGI1-IgG4 alone. We retrospectively assessed all anti-LGI1 encephalitis patients from this center with anti-LGI1-IgG-subclass information and follow-up MRI available. Nine out of 20 patients had developed HS (45%). Volumetric FreeSurfer analysis confirmed the visual HS diagnoses. HS and a lower hippocampal volume were associated with anti-LGI1-IgG1/2/3. All six patients with this IgG subclass status developed HS. There was no association with older or younger age at onset, female sex, longer latency from disease onset to start of immunotherapy, less intense immunotherapy, higher serum titers of LGI1 antibodies, LGI1 antibodies in CSF or higher LGI1-specific antibody indices. There was no association between anti-LGI1-IgG1/2/3 status and neuropsychological performance, epilepsy, or general neurological performance. This confirms our hypothesis that anti-LGI1-IgG1/2/3 in serum puts patients at risk of developing HS. If these findings can be confirmed and clinically corroborated, patients with anti-LGI1-IgG1/2/3 might become candidates for anti-complement-directed immunological treatments.
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Multiple sclerosis (MS) is characterized by heterogeneity in disease course and prediction of long-term outcome remains a major challenge. Here, we investigate five myeloid markers - CHIT1, CHI3L1, sTREM2, GPNMB and CCL18 - in the cerebrospinal fluid (CSF) at diagnostic lumbar puncture in a longitudinal cohort of 192 MS patients. Through mixed-effects and machine learning models, we show that CHIT1 is a robust predictor for faster disability progression. Integrative analysis of 11 CSF and 26 central nervous system (CNS) parenchyma single-cell/nucleus RNA sequencing samples reveals CHIT1 to be predominantly expressed by microglia located in active MS lesions and enriched for lipid metabolism pathways. Furthermore, we find CHIT1 expression to accompany the transition from a homeostatic towards a more activated, MS-associated cell state in microglia. Neuropathological evaluation in post-mortem tissue from 12 MS patients confirms CHIT1 production by lipid-laden phagocytes in actively demyelinating lesions, already in early disease stages. Altogether, we provide a rationale for CHIT1 as an early biomarker for faster disability progression in MS.
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Biomarcadores , Progressão da Doença , Microglia , Esclerose Múltipla , Humanos , Microglia/metabolismo , Microglia/patologia , Esclerose Múltipla/líquido cefalorraquidiano , Esclerose Múltipla/genética , Esclerose Múltipla/metabolismo , Esclerose Múltipla/diagnóstico , Esclerose Múltipla/patologia , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/metabolismo , Feminino , Masculino , Adulto , Pessoa de Meia-Idade , Hexosaminidases/metabolismo , Hexosaminidases/genética , Hexosaminidases/líquido cefalorraquidiano , Estudos Longitudinais , Proteína 1 Semelhante à Quitinase-3/líquido cefalorraquidiano , Proteína 1 Semelhante à Quitinase-3/metabolismo , Proteína 1 Semelhante à Quitinase-3/genéticaAssuntos
Autoanticorpos , Imunidade Inata , Peptídeos e Proteínas de Sinalização Intracelular , Encefalite Límbica , Imageamento por Ressonância Magnética , Proteínas de Membrana , Proteínas do Tecido Nervoso , Tomografia por Emissão de Pósitrons , Pirazóis , Humanos , Encefalite Límbica/imunologia , Encefalite Límbica/diagnóstico por imagem , Pirazóis/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Imunidade Inata/imunologia , Proteínas do Tecido Nervoso/imunologia , Autoanticorpos/imunologia , Proteínas de Membrana/imunologia , Pirimidinas , Feminino , Masculino , Pessoa de Meia-IdadeRESUMO
Activation of Bruton's tyrosine kinase (BTK) has been shown to play a crucial role in the proinflammatory response of B cells and myeloid cells upon engagement with B cell, Fc, Toll-like receptor, and distinct chemokine receptors. Previous reports suggest BTK actively contributes to the pathogenesis of multiple sclerosis (MS). The BTK inhibitor Evobrutinib has been shown to reduce the numbers of gadolinium-enhancing lesions and relapses in relapsing-remitting MS patients. In vitro, BTK inhibition resulted in reduced phagocytic activity and modulated BTK-dependent inflammatory signaling of microglia and macrophages. Here, we investigated the protein expression of BTK and CD68 as well as iron accumulation in postmortem control (n = 10) and MS (n = 23) brain tissue, focusing on microglia and macrophages. MS cases encompassed active, chronic active, and inactive lesions. BTK+ and iron+ cells positively correlated across all regions of interests and, along with CD68, revealed highest numbers in the center of active and at the rim of chronic active lesions. We then studied the effect of BTK inhibition in the human immortalized microglia-like HMC3 cell line in vitro. In particular, we loaded HMC3 cells with iron-dextran and subsequently administered the BTK inhibitor Evobrutinib. Iron treatment alone induced a proinflammatory phenotype and increased the expression of iron importers as well as the intracellular iron storage protein ferritin light chain (FTL). BTK inhibition of iron-laden cells dampened the expression of microglia-related inflammatory genes as well as iron-importers, whereas the iron-exporter ferroportin was upregulated. Our data suggest that BTK inhibition not only dampens the proinflammatory response but also reduces iron import and storage in activated microglia and macrophages with possible implications on microglial iron accumulation in chronic active lesions in MS.
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Tirosina Quinase da Agamaglobulinemia , Ferro , Esclerose Múltipla , Humanos , Tirosina Quinase da Agamaglobulinemia/metabolismo , Tirosina Quinase da Agamaglobulinemia/antagonistas & inibidores , Ferro/metabolismo , Masculino , Feminino , Esclerose Múltipla/metabolismo , Esclerose Múltipla/patologia , Pessoa de Meia-Idade , Adulto , Células Mieloides/metabolismo , Células Mieloides/patologia , Encéfalo/metabolismo , Encéfalo/patologia , Idoso , Microglia/metabolismo , Microglia/patologia , Macrófagos/metabolismo , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Pirimidinas/farmacologia , PiperidinasRESUMO
X-linked adrenoleukodystrophy (X-ALD), the most frequent, inherited peroxisomal disease, is caused by mutations in the ABCD1 gene encoding a peroxisomal lipid transporter importing very long-chain fatty acids (VLCFAs) from the cytosol into peroxisomes for degradation via ß-oxidation. ABCD1 deficiency results in accumulation of VLCFAs in tissues and body fluids of X-ALD patients with a wide range of phenotypic manifestations. The most severe variant, cerebral X-ALD (CALD) is characterized by progressive inflammation, loss of the myelin-producing oligodendrocytes and demyelination of the cerebral white matter. Whether the oligodendrocyte loss and demyelination in CALD are caused by a primary cell autonomous defect or injury to oligodendrocytes or by a secondary effect of the inflammatory reaction remains unresolved. To address the role of X-ALD oligodendrocytes in demyelinating pathophysiology, we combined the Abcd1 deficient X-ALD mouse model, in which VLCFAs accumulate without spontaneous demyelination, with the cuprizone model of toxic demyelination. In mice, the copper chelator cuprizone induces reproducible demyelination in the corpus callosum, followed by remyelination upon cuprizone removal. By immunohistochemical analyses of oligodendrocytes, myelin, axonal damage and microglia activation during de-and remyelination, we found that the mature oligodendrocytes of Abcd1 KO mice are more susceptible to cuprizone-induced cell death compared to WT mice in the early demyelinating phase. Furthermore, this effect was mirrored by a greater extent of acute axonal damage during demyelination in the KO mice. Abcd1 deficiency did not affect the function of microglia in either phase of the treatment. Also, the proliferation and differentiation of oligodendrocyte precursor cells and remyelination progressed at similar rates in both genotypes. Taken together, our findings point to an effect of Abcd1 deficiency on mature oligodendrocytes and the oligodendrocyte-axon unit, leading to increased vulnerability in the context of a demyelinating insult.
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Adrenoleucodistrofia , Animais , Camundongos , Adrenoleucodistrofia/induzido quimicamente , Adrenoleucodistrofia/genética , Adrenoleucodistrofia/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Cuprizona/toxicidade , Oligodendroglia/metabolismo , Bainha de Mielina/metabolismo , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Membro 1 da Subfamília D de Transportadores de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília D de Transportadores de Cassetes de Ligação de ATP/metabolismoRESUMO
Autoimmune limbic encephalitis (ALE) presents with new-onset mesial temporal lobe seizures, progressive memory disturbance, and other behavioral and cognitive changes. CD8 T cells are considered to play a key role in those cases where autoantibodies (ABs) target intracellular antigens or no ABs were found. Assessment of such patients presents a clinical challenge, and novel noninvasive imaging biomarkers are urgently needed. Here, we demonstrate that visualization of the translocator protein (TSPO) with [18F]DPA-714-PET-MRI reveals pronounced microglia activation and reactive gliosis in the hippocampus and amygdala of patients suspected with CD8 T cell ALE, which correlates with FLAIR-MRI and EEG alterations. Back-translation into a preclinical mouse model of neuronal antigen-specific CD8 T cell-mediated ALE allowed us to corroborate our preliminary clinical findings. These translational data underline the potential of [18F]DPA-714-PET-MRI as a clinical molecular imaging method for the direct assessment of innate immunity in CD8 T cell-mediated ALE.
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Encefalite Límbica , Animais , Humanos , Camundongos , Proteínas de Transporte/metabolismo , Inflamação/metabolismo , Encefalite Límbica/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Receptores de GABA/metabolismoRESUMO
OBJECTIVES: Vaccine-induced immune thrombotic thrombocytopenia (VITT), a recently described entity characterized by thrombosis at unusual locations such as cerebral venous sinus and splanchnic vein, has been rarely described after adenoviral-encoded COVID-19 vaccines. In this study, we report the immunohistological correlates in 3 fatal cases of cerebral venous thrombosis related to VITT analyzed at an academic medical center. METHODS: Detailed neuropathologic studies were performed in 3 cases of cerebral venous thrombosis related to VITT after adenoviral COVID-19 vaccination. RESULTS: Autopsy revealed extensive cerebral vein thrombosis in all 3 cases. Polarized thrombi were observed with a high density of neutrophils in the core and a low density in the tail. Endothelial cells adjacent to the thrombus were largely destroyed. Markers of neutrophil extracellular trap and complement activation were present at the border and within the cerebral vein thrombi. SARS-CoV-2 spike protein was detected within the thrombus and in the adjacent vessel wall. DISCUSSION: Data indicate that neutrophils and complement activation associated with antispike immunity triggered by the vaccine is probably involved in the disease process.
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COVID-19 , Trombocitopenia , Trombose , Vacinas , Trombose Venosa , Humanos , Vacinas contra COVID-19/efeitos adversos , Células Endoteliais , SARS-CoV-2 , Trombose Venosa/etiologiaRESUMO
TNF signaling is an essential regulator of cellular homeostasis. Through its two receptors TNFR1 and TNFR2, soluble versus membrane-bound TNF enable cell death or survival in a variety of cell types. TNF-TNFRs signaling orchestrates important biological functions such as inflammation, neuronal activity as well as tissue de- and regeneration. TNF-TNFRs signaling is a therapeutic target for neurodegenerative diseases such as multiple sclerosis (MS) and Alzheimer's disease (AD), but animal and clinical studies yielded conflicting findings. Here, we ask whether a sequential modulation of TNFR1 and TNFR2 signaling is beneficial in experimental autoimmune encephalomyelitis (EAE), an experimental mouse model that recapitulates inflammatory and demyelinating aspects of MS. To this end, human TNFR1 antagonist and TNFR2 agonist were administered peripherally at different stages of disease development in TNFR-humanized mice. We found that stimulating TNFR2 before onset of symptoms leads to improved response to anti-TNFR1 therapeutic treatment. This sequential treatment was more effective in decreasing paralysis symptoms and demyelination, when compared to single treatments. Interestingly, the frequency of the different immune cell subsets is unaffected by TNFR modulation. Nevertheless, treatment with only a TNFR1 antagonist increases T-cell infiltration in the central nervous system (CNS) and B-cell cuffing at the perivascular sites, whereas a TNFR2 agonist promotes Treg CNS accumulation. Our findings highlight the complicated nature of TNF signaling which requires a timely balance of selective activation and inhibition of TNFRs in order to exert therapeutic effects in the context of CNS autoimmunity.
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Encefalomielite Autoimune Experimental , Esclerose Múltipla , Receptores Tipo II do Fator de Necrose Tumoral , Receptores Tipo I de Fatores de Necrose Tumoral , Animais , Humanos , Camundongos , Sistema Nervoso Central/metabolismo , Encefalomielite Autoimune Experimental/metabolismo , Inflamação , Esclerose Múltipla/metabolismo , Receptores Tipo I de Fatores de Necrose Tumoral/agonistas , Receptores Tipo II do Fator de Necrose Tumoral/agonistas , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND AND OBJECTIVES: Alteration of the blood-brain barrier (BBB) at the interface between blood and CNS parenchyma is prominent in most neuroinflammatory diseases. In several neurologic diseases, including cerebral malaria and Susac syndrome, a CD8 T cell-mediated targeting of endothelial cells of the BBB (BBB-ECs) has been implicated in pathogenesis. METHODS: In this study, we used an experimental mouse model to evaluate the ability of a small-molecule perforin inhibitor to prevent neuroinflammation resulting from cytotoxic CD8 T cell-mediated damage of BBB-ECs. RESULTS: Using an in vitro coculture system, we first identified perforin as an essential molecule for killing of BBB-ECs by CD8 T cells. We then found that short-term pharmacologic inhibition of perforin commencing after disease onset restored motor function and inhibited the neuropathology. Perforin inhibition resulted in preserved BBB-EC viability, maintenance of the BBB, and reduced CD8 T-cell accumulation in the brain and retina. DISCUSSION: Therefore, perforin-dependent cytotoxicity plays a key role in the death of BBB-ECs inflicted by autoreactive CD8 T cells in a preclinical model and potentially represents a therapeutic target for CD8 T cell-mediated neuroinflammatory diseases, such as cerebral malaria and Susac syndrome.
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Malária Cerebral , Síndrome de Susac , Camundongos , Animais , Perforina , Doenças Neuroinflamatórias , Células Endoteliais , Camundongos Knockout , Linfócitos T CD8-Positivos , Modelos Animais de DoençasRESUMO
This study used cross-sectional UK Biobank data to estimate the influence of active and passive commuting modes and commuting distance on cardiovascular disease (CVD) -related biomarkers as measures of health outcomes. The analysis applied logistic regression to assess the risk of exhibiting individual biomarker values outside a predefined reference interval and standard linear regression to estimate the relation between commuting practices and a composite CVD index. The study sample comprised 208,893 UK Biobank baseline survey participants aged 40 to 69 who use various modes of transport to commute to work at least once a week. Participants were recruited and interviewed between 2006 and 2010 at 22 centers geographically dispersed across England, Scotland, and Wales. The data set included these participants' sociodemographic and health-related information, including lifestyle indicators and biological measures. The primary outcome was a shift from low to high-risk blood serum levels in eight cardiovascular biomarkers: total cholesterol, low density lipoprotein, high density lipoprotein, triglycerides, apolipoprotein A and B, C-reactive protein, and lipoprotein (a). Our results indicated a small negative association between the composite risk index for CVD biomarkers and weekly commuting distance. Although estimates for active commuting modes (cycling, walking) may admittedly be sensitive to different covariate adjustments, our specifications show them to be positively associated with select CVD biomarkers. Commuting long distances by car is negatively associated with CVD-related biomarkers, while cycling and walking might be positively associated. This biomarker-based evidence, although limited, is less susceptible to residual confounding than that from distant outcomes like CVD mortality.
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Doenças Cardiovasculares , Humanos , Estudos Transversais , Bancos de Espécimes Biológicos , Caminhada , Meios de Transporte , Inglaterra/epidemiologia , CiclismoRESUMO
Delineation of the autoimmune encephalitides with antibodies against neural surface antigens (anti-N-Methyl-D-aspartate, anti-leucine-rich glioma-inactivated protein 1, and others), autoimmune-associated epilepsies (Rasmussen encephalitis, paraneoplastic encephalitides, temporal lobe epilepsy with antibodies against glutamic acid decarboxylase), and encephalomyelitides with glial antibodies (neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein antibody disease) has been a major advance in neurology. But how do these inflammatory diseases "work"? What kind of interaction between elements of the immune system and brain cells leads to these conditions? The only direct way of answering these questions is to investigate affected brain tissue by neuropathological techniques. They provide morphological and, in part, temporal information on the elements and localization of the disease process. Molecular techniques broaden and support these data. Brain tissue becomes available through autopsies and brain biopsies, obtained for diagnostic or therapeutic interventions. The limitations of neuropathological pathogenic research are discussed. Finally, representative neuropathological findings in autoimmune encephalitides and related conditions are summarized.
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Doenças Autoimunes do Sistema Nervoso , Encefalite , Epilepsia , Humanos , Encefalite/patologia , Encéfalo/patologia , Neuropatologia , AutoanticorposRESUMO
AIMS: Many patients with neuromyelitis optica spectrum disorders (NMOSD) suffer from cognitive impairment affecting memory, processing speed and attention and suffer from depressive symptoms. Because some of these manifestations could trace back to the hippocampus, several magnetic resonance imaging (MRI) studies have been performed in the past, with a number of groups describing volume loss of the hippocampus in NMOSD patients, whereas others did not observe such changes. Here, we addressed these discrepancies. METHODS: We performed pathological and MRI studies on the hippocampi of NMOSD patients, combined with detailed immunohistochemical analysis of hippocampi from experimental models of NMOSD. RESULTS: We identified different pathological scenarios for hippocampal damage in NMOSD and its experimental models. In the first case, the hippocampus was compromised by the initiation of astrocyte injury in this brain region and subsequent local effects of microglial activation and neuronal damage. In the second case, loss of hippocampal volume was seen by MRI in patients with large tissue-destructive lesions in the optic nerves or the spinal cord, and the pathological work-up of tissue derived from a patient with such lesions revealed subsequent retrograde neuronal degeneration affecting different axonal tracts and neuronal networks. It remains to be seen whether remote lesions and associated retrograde neuronal degeneration on their own are sufficient to cause extensive volume loss of the hippocampus, or whether they act in concert with small astrocyte-destructive, microglia-activating lesions in the hippocampus that escape detection by MRI, either due to their small size or due to the chosen time window for examination. CONCLUSIONS: Different pathological scenarios can culminate in hippocampal volume loss in NMOSD patients.
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Neuromielite Óptica , Humanos , Neuromielite Óptica/patologia , Medula Espinal/patologia , Encéfalo/patologia , Imageamento por Ressonância Magnética , Hipocampo/patologia , Autoanticorpos , Aquaporina 4RESUMO
Inherited deficiency in ether lipids, a subgroup of glycerophospholipids with unique biochemical and biophysical properties, evokes severe symptoms in humans resulting in a multi-organ syndrome. Mouse models with defects in ether lipid biosynthesis have widely been used to understand the pathophysiology of human disease and to study the roles of ether lipids in various cell types and tissues. However, little is known about the function of these lipids in cardiac tissue. Previous studies included case reports of cardiac defects in ether-lipid-deficient patients, but a systematic analysis of the impact of ether lipid deficiency on the mammalian heart is still missing. Here, we utilize a mouse model of complete ether lipid deficiency (Gnpat KO) to accomplish this task. Similar to a subgroup of human patients with rhizomelic chondrodysplasia punctata (RCDP), a fraction of Gnpat KO fetuses present with defects in ventricular septation, presumably evoked by a developmental delay. We did not detect any signs of cardiomyopathy but identified increased left ventricular end-systolic and end-diastolic pressure in middle-aged ether-lipid-deficient mice. By comprehensive electrocardiographic characterization, we consistently found reduced ventricular conduction velocity, as indicated by a prolonged QRS complex, as well as increased QRS and QT dispersion in the Gnpat KO group. Furthermore, a shift of the Wenckebach point to longer cycle lengths indicated depressed atrioventricular nodal function. To complement our findings in mice, we analyzed medical records and performed electrocardiography in ether-lipid-deficient human patients, which, in contrast to the murine phenotype, indicated a trend towards shortened QT intervals. Taken together, our findings demonstrate that the cardiac phenotype upon ether lipid deficiency is highly heterogeneous, and although the manifestations in the mouse model only partially match the abnormalities in human patients, the results add to our understanding of the physiological role of ether lipids and emphasize their importance for proper cardiac development and function.
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Éter , Plasmalogênios , Animais , Humanos , Camundongos , Éteres , Etil-Éteres , Coração , Mamíferos/metabolismoRESUMO
Temporal lobe epilepsy (TLE) is one of the syndromes linked to antibodies against glutamic acid decarboxylase (GAD). It has been questioned whether 'limbic encephalitis with GAD antibodies' is a meaningful diagnostic entity. The immunopathogenesis of GAD-TLE has remained enigmatic. Improvement of immunological treatability is an urgent clinical concern. We retrospectively assessed the clinical, MRI and CSF course as well as brain tissue of 15 adult patients with GAD-TLE who underwent temporal lobe surgery. Brain tissue was studied by means of immunohistochemistry, multiplex fluorescent microscopy and transcriptomic analysis for inflammatory mediators and neuronal degeneration. In 10 patients, there was a period of mediotemporal swelling and T2 signal increase; in nine cases this occurred within the first 6 years after symptom onset. This resulted in unilateral or bilateral hippocampal sclerosis; three cases developed hippocampal sclerosis within the first 2 years. All CSF studies done within the first year (n = 6) revealed intrathecal synthesis of immunoglobulin G. Temporal lobe surgeries were done after a median disease duration of 9 years (range 3 weeks to 60 years). Only two patients became seizure-free. Brain parenchyma collected during surgery in the first 6 years revealed high numbers of plasma cells but no signs of antibody-mediated tissue damage. Even more dense was the infiltration by CD8+ cytotoxic T lymphocytes (CTLs) that were seen to locally proliferate. Further, a portion of these cells revealed an antigen-specific resident memory T cell phenotype. Finally, CTLs with cytotoxic granzyme B+ granules were also seen in microglial nodules and attached to neurons, suggesting a CTL-mediated destruction of these cells. With longer disease duration, the density of all lymphocytes decreased. Whole transcriptome analysis in early/active cases (but not in late/inactive stages) revealed 'T cell immunity' and 'Regulation of immune processes' as the largest overrepresented clusters. To a lesser extent, pathways associated with B cells and neuronal degeneration also showed increased representation. Surgically treated patients with GAD-TLE go through an early active inflammatory, 'encephalitic' stage (≤6 years) with CTL-mediated, antigen-driven neuronal loss and antibody-producing plasma cells but without signs of complement-mediated cell death. Subsequently, patients enter an apparently immunologically inactive or low-active stage with ongoing seizures, probably caused by the structural damage to the temporal lobe. 'Limbic encephalitis' with GAD antibodies should be subsumed under GAD-TLE. The early tissue damage explains why immunotherapy does not usually lead to freedom from seizures.
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Encefalite , Epilepsia do Lobo Temporal , Encefalite Límbica , Humanos , Epilepsia do Lobo Temporal/complicações , Complexo de Ataque à Membrana do Sistema Complemento , Estudos Retrospectivos , Convulsões/complicações , Glutamato Descarboxilase , Imunoglobulina G , Encefalite/complicações , Encefalite Límbica/complicações , Neurônios/metabolismo , Imageamento por Ressonância Magnética/métodosRESUMO
Very long-chain fatty acids (VLCFA) are critical for human cytomegalovirus replication and accumulate upon infection. Here, we used Epstein-Barr virus (EBV) infection of human B cells to elucidate how herpesviruses target VLCFA metabolism. Gene expression profiling revealed that, despite a general induction of peroxisome-related genes, EBV early infection decreased expression of the peroxisomal VLCFA transporters ABCD1 and ABCD2, thus impairing VLCFA degradation. The mechanism underlying ABCD1 and ABCD2 repression involved RNA interference by the EBV-induced microRNAs miR-9-5p and miR-155, respectively, causing significantly increased VLCFA levels. Treatment with 25-hydroxycholesterol, an antiviral innate immune modulator produced by macrophages, restored ABCD1 expression and reduced VLCFA accumulation in EBV-infected B-lymphocytes, and, upon lytic reactivation, reduced virus production in control but not ABCD1-deficient cells. Finally, also other herpesviruses and coronaviruses target ABCD1 expression. Because viral infection might trigger neuroinflammation in X-linked adrenoleukodystrophy (X-ALD, inherited ABCD1 deficiency), we explored a possible link between EBV infection and cerebral X-ALD. However, neither immunohistochemistry of post-mortem brains nor analysis of EBV seropositivity in 35 X-ALD children supported involvement of EBV in the onset of neuroinflammation. Collectively, our findings indicate a previously unrecognized, pivotal role of ABCD1 in viral infection and host defence, prompting consideration of other viral triggers in cerebral X-ALD.
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Adrenoleucodistrofia , Infecções por Vírus Epstein-Barr , Herpesviridae , Adrenoleucodistrofia/genética , Antivirais , Criança , Infecções por Vírus Epstein-Barr/genética , Ácidos Graxos , Herpesviridae/genética , Herpesvirus Humano 4/genética , HumanosRESUMO
BACKGROUND AND OBJECTIVES: Paraneoplastic cerebellar degeneration (PCD) is characterized by a widespread loss of Purkinje cells (PCs) and may be associated with autoantibodies against intracellular antigens such as Yo or cell surface neuronal antigens such as the P/Q-type voltage-gated calcium channel (P/Q-VGCC). Although the intracellular location of the target antigen in anti-Yo-PCD supports a T cell-mediated pathology, the immune mechanisms in anti-P/Q-VGCC-PCD remain unclear. In this study, we compare neuropathologic characteristics of PCD with anti-P/Q-VGCC and anti-Yo autoantibodies in an archival autopsy cohort. METHODS: We performed neuropathology, immunohistochemistry, and multiplex immunofluorescence on formalin-fixed and paraffin-embedded brain tissue of 1 anti-P/Q-VGCC, 2 anti-Yo-PCD autopsy cases and controls. RESULTS: Anti-Yo-PCD revealed a diffuse and widespread PC loss together with microglial nodules with pSTAT1+ and CD8+granzymeB+ T cells and neuronal upregulation of major histocompatibility complex (MHC) Class I molecules. Some neurons showed a cytoplasmic immunoglobulin G (IgG) staining. In contrast, PC loss in anti-P/Q-VGCC-PCD was focal and predominantly affected the upper vermis, whereas caudal regions and lateral hemispheres were spared. Inflammation was characterized by scattered CD8+ T cells, single CD20+/CD79a+ B/plasma cells, and an IgG staining of the neuropil in the molecular layer of the cerebellar cortex and neuronal cytoplasms. No complement deposition or MHC-I upregulation was detected. Moreover, synaptophysin was reduced, and neuronal P/Q-VGCC was downregulated. In affected areas, axonal spheroids and the accumulation of amyloid precursor protein and glucose-regulated protein 78 in PCs indicate endoplasmatic reticulum stress and impairment of axonal transport. In both PCD types, calbindin expression was reduced or lost in the remaining PCs. DISCUSSION: Anti-Yo-PCD showed characteristic features of a T cell-mediated pathology, whereas this was not observed in 1 case of anti-P/Q-VGCC-PCD. Our findings support a pathogenic role of anti-P/Q-VGCC autoantibodies in causing neuronal dysfunction, probably due to altered synaptic transmission resulting in calcium dysregulation and subsequent PC death. Because disease progression may lead to irreversible PC loss, anti-P/Q-VGCC-PCD patients could benefit from early oncologic and immunologic therapies.
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Degeneração Paraneoplásica Cerebelar , Anticorpos Antineoplásicos , Autoanticorpos , Linfócitos T CD8-Positivos , Canais de Cálcio Tipo Q , Humanos , Imunoglobulina G , Proteínas do Tecido NervosoRESUMO
Narcolepsy with cataplexy or narcolepsy type 1 is a disabling chronic sleep disorder resulting from the destruction of orexinergic neurons in the hypothalamus. The tight association of narcolepsy with HLA-DQB1*06:02 strongly suggest an autoimmune origin to this disease. Furthermore, converging epidemiological studies have identified an increased incidence for narcolepsy in Europe following Pandemrix® vaccination against the 2009-2010 pandemic 'influenza' virus strain. The potential immunological link between the Pandemrix® vaccination and narcolepsy remains, however, unknown. Deciphering these mechanisms may reveal pathways potentially at play in most cases of narcolepsy. Here, we developed a mouse model allowing to track and study the T-cell response against 'influenza' virus haemagglutinin, which was selectively expressed in the orexinergic neurons as a new self-antigen. Pandemrix® vaccination in this mouse model resulted in hypothalamic inflammation and selective destruction of orexin-producing neurons. Further investigations on the relative contribution of T-cell subsets in this process revealed that haemagglutinin-specific CD4 T cells were necessary for the development of hypothalamic inflammation, but insufficient for killing orexinergic neurons. Conversely, haemagglutinin-specific CD8 T cells could not initiate inflammation but were the effectors of the destruction of orexinergic neurons. Additional studies revealed pathways potentially involved in the disease process. Notably, the interferon-γ pathway was proven essential, as interferon-γ-deficient CD8 T cells were unable to elicit the loss of orexinergic neurons. Our work demonstrates that an immunopathological process mimicking narcolepsy can be elicited by immune cross-reactivity between a vaccine antigen and a neuronal self-antigen. This process relies on a synergy between autoreactive CD4 and CD8 T cells for disease development. This work furthers our understanding of the mechanisms and pathways potentially involved in the development of a neurological side effect due to a vaccine and, likely, to narcolepsy in general.
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Autoimunidade , Vacinas contra Influenza , Narcolepsia , Animais , Autoantígenos , Hemaglutininas , Inflamação/complicações , Vacinas contra Influenza/efeitos adversos , Interferon gama , Camundongos , Narcolepsia/induzido quimicamente , Neurônios , Orexinas , Linfócitos T/imunologia , Vacinação/efeitos adversosRESUMO
Rett syndrome (RTT) is a neurodevelopmental disorder caused by pathogenic variants leading to functional impairment of the MeCP2 protein. Here, we used purified recombinant MeCP2e1 and MeCP2e2 protein variants fused to a TAT protein transduction domain (PTD) to evaluate their transduction ability into RTT patient-derived fibroblasts and the ability to carry out their cellular function. We then assessed their transduction ability and therapeutic effects in a RTT mouse model. In vitro, TAT-MeCP2e2-eGFP reversed the pathological hyperacetylation of histones H3K9 and H4K16, a hallmark of abolition of MeCP2 function. In vivo, intraperitoneal administration of TAT-MeCP2e1 and TAT-MeCP2e2 extended the lifespan of Mecp2-/y mice by >50%. This was accompanied by rescue of hippocampal CA2 neuron size in animals treated with TAT-MeCP2e1. Taken together, these findings provide a strong indication that recombinant TAT-MeCP2 can reach mouse brains following peripheral injection and can ameliorate the phenotype of RTT mouse models. Thus, our study serves as a first step in the development of a potentially novel RTT therapy.
Assuntos
Síndrome de Rett , Animais , Modelos Animais de Doenças , Produtos do Gene tat/genética , Produtos do Gene tat/uso terapêutico , Humanos , Proteína 2 de Ligação a Metil-CpG/genética , Proteína 2 de Ligação a Metil-CpG/metabolismo , Camundongos , Mutação , Fenótipo , Síndrome de Rett/tratamento farmacológico , Síndrome de Rett/genética , Síndrome de Rett/metabolismoRESUMO
The mechanisms underlying the chronicity of autoimmune diseases of the central nervous system (CNS) are largely unknown. In particular, it is unclear whether tissue-resident memory T cells (TRM) contribute to lesion pathogenesis during chronic CNS autoimmunity. Here, we observed that a high frequency of brain-infiltrating CD8+ T cells exhibit a TRM-like phenotype in human autoimmune encephalitis. Using mouse models of neuronal autoimmunity and a combination of T single-cell transcriptomics, high-dimensional flow cytometry, and histopathology, we found that pathogenic CD8+ T cells behind the blood-brain barrier adopt a characteristic TRM differentiation program, and we revealed their phenotypic and functional heterogeneity. In the diseased CNS, autoreactive tissue-resident CD8+ T cells sustained focal neuroinflammation and progressive loss of neurons, independently of recirculating CD8+ T cells. Consistently, a large fraction of autoreactive tissue-resident CD8+ T cells exhibited proliferative potential as well as proinflammatory and cytotoxic properties. Persistence of tissue-resident CD8+ T cells in the CNS and their functional output, but not their initial differentiation, were crucially dependent on CD4+ T cells. Collectively, our results point to tissue-resident CD8+ T cells as essential drivers of chronic CNS autoimmunity and suggest that therapies targeting this compartmentalized autoreactive T cell subset might be effective for treating CNS autoimmune diseases.