Objective
Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease of unknown etiology. Although the prevalent view regards a CD4+‐lymphocyte autoimmune reaction against ...myelin at the root of the disease, recent studies propose autoimmunity as a secondary reaction to idiopathic brain damage. To gain knowledge about this possibility we investigated the presence of axonal and myelinic morphological alterations, which could implicate imbalance of axon‐myelin units as primary event in MS pathogenesis.
Methods
Using high resolution imaging histological brain specimens from patients with MS and non‐neurological/non‐MS controls, we explored molecular changes underpinning imbalanced interaction between axon and myelin in normal appearing white matter (NAWM), a region characterized by normal myelination and absent inflammatory activity.
Results
In MS brains, we detected blister‐like swellings formed by myelin detachment from axons, which were substantially less frequently retrieved in non‐neurological/non‐MS controls. Swellings in MS NAWM presented altered glutamate receptor expression, myelin associated glycoprotein (MAG) distribution, and lipid biochemical composition of myelin sheaths. Changes in tethering protein expression, widening of nodes of Ranvier and altered distribution of sodium channels in nodal regions of otherwise normally myelinated axons were also present in MS NAWM. Finally, we demonstrate a significant increase, compared with controls, in citrullinated proteins in myelin of MS cases, pointing toward biochemical modifications that may amplify the immunogenicity of MS myelin.
Interpretation
Collectively, the impaired interaction of myelin and axons potentially leads to myelin disintegration. Conceptually, the ensuing release of (post‐translationally modified) myelin antigens may elicit a subsequent immune attack in MS. ANN NEUROL 2021;89:711–725
Multiple sclerosis (MS) is a debilitating disease characterized by demyelination of the central nervous system (CNS), resulting in widespread formation of white matter lesions (WMLs) and grey matter ...lesions (GMLs). WMLs are pathologically characterized by the presence of immune cells that infiltrate the CNS, whereas these immune cells are barely present in GMLs. This striking pathological difference between WMLs and GMLs raises questions about the underlying mechanism. It is known that infiltrating leukocytes contribute to the generation of WMLs; however, since GMLs show a paucity of infiltrating immune cells, their importance in GML formation remains to be determined. Here, we review pathological characteristics of WMLs and GMLs, and suggest some possible explanations for the observed pathological differences. In our view, cellular and molecular characteristics of WM and GM, and local differences within WMLs and GMLs (in particular, in glial cell populations and the molecules they express), determine the pathway to demyelination. Further understanding of GML pathogenesis, considered to contribute to chronic MS, may have a direct impact on the development of novel therapeutic targets to counteract this progressive neurological disorder.
Summary Background In critically ill patients, antibiotic therapy is of great importance but long duration of treatment is associated with the development of antimicrobial resistance. Procalcitonin ...is a marker used to guide antibacterial therapy and reduce its duration, but data about safety of this reduction are scarce. We assessed the efficacy and safety of procalcitonin-guided antibiotic treatment in patients in intensive care units (ICUs) in a health-care system with a comparatively low use of antibiotics. Methods We did a prospective, multicentre, randomised, controlled, open-label intervention trial in 15 hospitals in the Netherlands. Critically ill patients aged at least 18 years, admitted to the ICU, and who received their first dose of antibiotics no longer than 24 h before inclusion in the study for an assumed or proven infection were eligible to participate. Patients who received antibiotics for presumed infection were randomly assigned (1:1), using a computer-generated list, and stratified (according to treatment centre, whether infection was acquired before or during ICU stay, and dependent on severity of infection ie, sepsis, severe sepsis, or septic shock) to receive either procalcitonin-guided or standard-of-care antibiotic discontinuation. Both patients and investigators were aware of group assignment. In the procalcitonin-guided group, a non-binding advice to discontinue antibiotics was provided if procalcitonin concentration had decreased by 80% or more of its peak value or to 0·5 μg/L or lower. In the standard-of-care group, patients were treated according to local antibiotic protocols. Primary endpoints were antibiotic daily defined doses and duration of antibiotic treatment. All analyses were done by intention to treat. Mortality analyses were completed for all patients (intention to treat) and for patients in whom antibiotics were stopped while being on the ICU (per-protocol analysis). Safety endpoints were reinstitution of antibiotics and recurrent inflammation measured by C-reactive protein concentrations and they were measured in the population adhering to the stopping rules (per-protocol analysis). The study is registered with ClinicalTrials.gov , number NCT01139489 , and was completed in August, 2014. Findings Between Sept 18, 2009, and July 1, 2013, 1575 of the 4507 patients assessed for eligibility were randomly assigned to the procalcitonin-guided group (761) or to standard-of-care (785). In 538 patients (71%) in the procalcitonin-guided group antibiotics were discontinued in the ICU. Median consumption of antibiotics was 7·5 daily defined doses (IQR 4·0–12·7) in the procalcitonin-guided group versus 9·3 daily defined doses (5·0–16·6) in the standard-of-care group (between-group absolute difference 2·69, 95% CI 1·26–4·12, p<0·0001). Median duration of treatment was 5 days (3–9) in the procalcitonin-guided group and 7 days (4–11) in the standard-of-care group (between-group absolute difference 1·22, 0·65–1·78, p<0·0001). Mortality at 28 days was 149 (20%) of 761 patients in the procalcitonin-guided group and 196 (25%) of 785 patients in the standard-of-care group (between-group absolute difference 5·4%, 95% CI 1·2–9·5, p=0·0122) according to the intention-to-treat analysis, and 107 (20%) of 538 patients in the procalcitonin-guided group versus 121 (27%) of 457 patients in the standard-of-care group (between-group absolute difference 6·6%, 1·3–11·9, p=0·0154) in the per-protocol analysis. 1-year mortality in the per-protocol analysis was 191 (36%) of 538 patients in the procalcitonin-guided and 196 (43%) of 457 patients in the standard-of-care groups (between-group absolute difference 7·4, 1·3–13·8, p=0·0188). Interpretation Procalcitonin guidance stimulates reduction of duration of treatment and daily defined doses in critically ill patients with a presumed bacterial infection. This reduction was associated with a significant decrease in mortality. Procalcitonin concentrations might help physicians in deciding whether or not the presumed infection is truly bacterial, leading to more adequate diagnosis and treatment, the cornerstones of antibiotic stewardship. Funding Thermo Fisher Scientific.
The advent of RNA‐sequencing techniques has made it possible to generate large, unbiased gene expression datasets of tissues and cell types. Several studies describing gene expression data of ...microglia from Alzheimer's disease or multiple sclerosis have been published, aiming to generate more insight into the role of microglia in these neurological diseases. Though the raw sequencing data are often deposited in open access databases, the most accessible source of data for scientists is what is reported in published manuscripts. We observed a relatively limited overlap in reported differentially expressed genes between various microglia RNA‐sequencing studies from multiple sclerosis or Alzheimer's diseases. It was clear that differences in experimental set up influenced the number of overlapping reported genes. However, even when the experimental set up was very similar, we observed that overlap in reported genes could be low. We identified that papers reporting large numbers of differentially expressed microglial genes generally showed higher overlap with other papers. In addition, though the pathology present within the tissue used for sequencing can greatly influence microglia gene expression, often the pathology present in samples used for sequencing was underreported, leaving it difficult to assess the data. Whereas reanalyzing every raw dataset could reduce the variation that contributes to the observed limited overlap in reported genes, this is not feasible for labs without (access to) bioinformatic expertise. In this study, we thus provide an overview of data present in manuscripts and their supplementary files and how these data can be interpreted.
Main Points
Little overlap in reported genes in microglia RNAseq studies of human tissue or animal models for AD or MS.
Considerable differences are observed in methodology, brain tissue and pathology of animal models used, and number of reported genes.
The olfactory bulb (OB) is affected early in both Parkinson's (PD) and Alzheimer's disease (AD), evidenced by the presence of disease‐specific protein aggregates and an early loss of olfaction. ...Whereas previous studies showed amoeboid microglia in the classically affected brain regions of PD and AD patients, little was known about such changes in the OB. Using a morphometric approach, a significant increase in amoeboid microglia density within the anterior olfactory nucleus (AON) of AD and PD patients was observed. These amoeboid microglia cells were in close apposition to β‐amyloid, hyperphosphorylated tau or α‐synuclein deposits, but no uptake of pathological proteins by microglia could be visualized. Subsequent analysis showed (i) no correlation between microglia and α‐synuclein (PD), (ii) a positive correlation with β‐amyloid (AD), and (iii) a negative correlation with hyperphosphorylated tau (AD). Furthermore, despite the observed pathological alterations in neurite morphology, neuronal loss was not apparent in the AON of both patient groups. Thus, we hypothesize that, in contrast to the classically affected brain regions of AD and PD patients, within the AON rather than neuronal loss, the increased density in amoeboid microglial cells, possibly in combination with neurite pathology, may contribute to functional deficits.
Belowground herbivores are overseen and underestimated, even though they can cause significant economic losses in agriculture. The cabbage root fly Delia radicum (Anthomyiidae) is a common pest in ...Brassica species, including agriculturally important crops, such as oilseed rape. The damage is caused by the larvae, which feed specifically on the taproots of Brassica plants until they pupate. The adults are aboveground‐living generalists feeding on pollen and nectar. Female flies are attracted by chemical cues in Brassica plants for oviposition. An assembled and annotated genome can elucidate which genetic mechanisms underlie the adaptation of D. radicum to its host plants and their specific chemical defences, in particular isothiocyanates. Therefore, we assembled, annotated and analysed the D. radicum genome using a combination of different next‐generation sequencing and bioinformatic approaches. We assembled a chromosome‐level D. radicum genome using PacBio and Hi‐C Illumina sequence data. Combining Canu and 3D‐DNA genome assembler, we constructed a 1.3 Gbp genome with an N50 of 242 Mbp and 6 pseudo‐chromosomes. To annotate the assembled D. radicum genome, we combined homology‐, transcriptome‐ and ab initio‐prediction approaches. In total, we annotated 13,618 genes that were predicted by at least two approaches. We analysed egg, larval, pupal and adult transcriptomes in relation to life‐stage specific molecular functions. This high‐quality annotated genome of D. radicum is a first step to understanding the genetic mechanisms underlying host plant adaptation. As such, it will be an important resource to find novel and sustainable approaches to reduce crop losses to these pests.
Zusammenfassung
Obwohl unterirdische Herbivoren einen erheblichen wirtschaftlichen Verlust in der Landwirtschaft verursachen können, werden sie übersehen und unterschätzt. Die Kleine Kohlfliege Delia radicum (Anthomyiidae) ist ein weit verbreiteter Schädling auf Brassica‐Arten, darunter sind auch wichtige Nutzpflanzen, wie der Raps. Der Schaden wird von den Larven verursacht, die bis zur Verpuppung ausschließlich an den Pfahlwurzeln der Brassica‐Pflanzen fressen. Die adulten Fliegen sind oberirdisch‐lebende Generalisten, die sich von Pollen und Nektar ernähren. Die Weibchen werden von chemischen Signalen der Brassica‐Pflanzen angezogen, wo die Eiablage stattfindet. Ein assembliertes und annotiertes Genom kann Aufschluss über molekulare Mechanismen geben, die der Anpassung von D. radicum an ihre Wirtspflanzen und deren spezifischen chemischen Abwehrstoffe, vor allem Isothiocyanate, zugrunde liegen. Mit einer Kombination aus unterschiedlichen Next‐Generation‐Sequencing‐Methoden und bioinformatischen Ansätzen haben, wir das Genom von D. radicum assembliert, annotiert und analysiert. Wir assemblierten ein D. radicum‐Genom auf Chromosmenebene unter Verwendung von PacBio und Hi‐C Illumina‐Sequenzdaten. Durch die Kombination von Canu und dem 3D‐DNA Genomassembler konnten wir ein 1,3 Gbp großes Genom mit einem N50 von 242 Mbp und 6 Pseudo‐Chromosomen erstellen. Für die Annotation des Genoms, haben wir homologie‐ und transkriptom‐basierte und ab initio Gen‐Vorhersagemodelle verwendet. Insgesamt haben wir 13.618 Gene annotiert, die von mindestens zwei der Ansätze vorhergesagt wurden. Weiterhin analysierten wir die Transkriptome von Eiern, Larven, Puppen und adulten Tieren in Bezug auf entwicklungsstadienspezifische molekulare Funktionen. Dieses qualitativ hochwertige annotierte Genom von D. radicum, ist ein erster Schritt zum Verständnis der genetischen Mechanismen, die der Anpassung an Wirtspflanzen zugrunde liegen. Es bildet eine wichtige Ressource für die Entwicklung neuer und nachhaltiger Ansätze zur Verringerung von Ertragsverlusten durch diesen Schädling.
Highlights • Aβ is differently altered depending on the age/neuropathology by early-life stress. • Neuroinflammation is affected through life by early-life stress in C57Bl/6 mice. • Neuroinflammatory ...response to Aβ is modulated by early-life stress in APP/PS1 mice. • Hippocampus is more affected by early-life stress compared to the entorhinal cortex.
Next to α-synuclein deposition, microglial activation is a prominent pathological feature in the substantia nigra (SN) of Parkinson's disease (PD) patients. Little is known, however, about the ...different phenotypes of microglia and how they change during disease progression, in the SN or in another brain region, like the hippocampus (HC), which is implicated in dementia and depression, important non-motor symptoms in PD. We studied phenotypes and activation of microglia in the SN and HC of established PD patients (Braak PD stage 4–6), matched controls (Braak PD stage 0) and of incidental Lewy Body disease (iLBD) cases (Braak PD stage 1–3) that are considered a prodromal state of PD. As recent experimental studies suggested that toll-like receptor 2 (TLR2) mediates α-synuclein triggered microglial activation, we also studied whether TLR2 expression is indeed related to pathology in iLBD and PD patients. A clear α-synuclein pathology-related increase in amoeboid microglia was present in the HC and SN in PD. Also, morphologically primed/reactive microglial cells, and a profound increase in microglial TLR2 expression were apparent in iLBD, but not PD, cases, indicative of an early activational response to PD pathology. Moreover, TLR2 was differentially expressed between the SN and HC, consistent with a region-specific pattern of microglial activation. In conclusion, the regional changes in microglial phenotype and TLR2 expression in primed/reactive microglia in the SN and HC of iLBD cases indicate that TLR2 may play a prominent role in the microglial-mediated responses that could be important for PD progression.
Exposure to stress is one of the best-known negative regulators of adult neurogenesis (AN). We discuss changes in neurogenesis in relation to exposure to stress, glucocorticoid hormones, and ...inflammation, with a particular focus on early development and on lasting effects of stress. Although the effects of acute and mild stress on AN are generally brief and can be quickly overcome, chronic exposure or more severe forms of stress can induce longer lasting reductions in neurogenesis that can, however, in part, be overcome by subsequent exposure to exercise, drugs targeting the stress system, and some antidepressants. Exposure to stress, particularly during the sensitive period of early life, may (re)program brain plasticity, in particular, in the hippocampus. This may increase the risk to develop cognitive or anxiety symptoms, common to brain diseases like dementia and depression in which plasticity changes occur, and a normalization of neurogenesis may be required for a successful treatment response and recovery.
Multiple Sclerosis (MS) is the most common cause of acquired neurological disability in young adults, pathologically characterized by leukocyte infiltration of the central nervous system, ...demyelination of the white and grey matter, and subsequent axonal loss. Microglia are proposed to play a role in MS lesion formation, however previous literature has not been able to distinguish infiltrated macrophages from microglia. Therefore, in this study we utilize the microglia-specific, homeostatic markers TMEM119 and P2RY12 to characterize their immunoreactivity in MS grey matter lesions in comparison to white matter lesions. Furthermore, we assessed the immunological status of the white and grey matter lesions, as well as the responsivity of human white and grey matter derived microglia to inflammatory mediators. We are the first to show that white and grey matter lesions in post-mortem human material differ in their immunoreactivity for the homeostatic microglia-specific markers TMEM119 and P2RY12. In particular, whereas immunoreactivity for TMEM119 and P2RY12 is decreased in the center of WMLs, immunoreactivity for both markers is not altered in GMLs. Based on data from post-mortem human microglia cultures, treated with IL-4 or IFNγ+LPS and on counts of CD3
or CD20
lymphocytes in lesions, we show that downregulation of TMEM119 and P2RY12 immunoreactivity in MS lesions corresponds with the presence of lymphocytes and lymphocyte-derived cytokines within the parenchyma but not in the meninges. Furthermore, the presence of TMEM119
and partly P2RY12
microglia in pre-active lesions as well as in the rim of active white and grey matter lesions, in addition to TMEM119
and P2RY12
rod-like microglia in subpial grey matter lesions suggest that blocking the entrance of lymphocytes into the CNS of MS patients may not interfere with all possible effects of TMEM119
and P2RY12
microglia in both white and grey matter MS lesions.
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