Remyelination in the CNS is the natural process of damage repair in demyelinating diseases such as multiple sclerosis (MS). However, remyelination becomes inadequate in many people with MS, which ...results in axonal degeneration and clinical disability. Enhancement of remyelination is a logical therapeutic goal; nevertheless, all currently licensed therapies for MS are immunomodulatory and do not support remyelination directly. Several molecular pathways have been identified as potential therapeutic targets to induce remyelination, and some of these have now been assessed in proof-of-concept clinical trials. However, trial design faces several obstacles: optimal clinical or paraclinical outcome measures to assess remyelination remain ill-defined, and identification of the ideal timing of therapy is also a crucial issue. In addition, realistic expectations are needed concerning the probable benefits of such therapies. Nevertheless, approaches that enhance remyelination are likely to be protective for axons and so could prevent long-term neurodegeneration. Future MS treatment paradigms, therefore, are likely to comprise a combinatorial approach that involves both immunomodulatory and regenerative treatments.
The damage of axons and neurons in multiple sclerosis (MS) is well recognised and correlates with neurological disability. The reasons leading to axonal and neuronal injury are diverse and possibly ...change from an inflammatory mediated mechanism to a neurodegenerative mechanism over the course of the disease. Acute axonal injury is associated with inflammation in the CNS and thus immunomodulatory treatments may also protect neurons from further damage. However, more effective immune treatments also bear the risk for severe side effects. Thus, neuroprotection will become more important to be combined with safe immunomodulation. Although several targets for neuroprotection have been identified experimentally, the translation into clinical treatments proves very difficult. Only few and small trials have investigated substances that may be neuroprotective, however, none had proven to have a substantial effect in MS patients. Clinical trials of remyelination, considered as a natural way of neuroprotection, were likewise not able to achieve clinical benefit. Thus, the development of a neuroprtective treatment in MS will be a major challenge in the decades to come.
Recent evidence suggests that astrocytes play an important role in regulating de- and remyelination in multiple sclerosis. The role of astrocytes is controversial, and both beneficial as well as ...detrimental effects are being discussed. We performed loss-of-function studies based on astrocyte depletion in a cuprizone-induced rodent model of demyelination. This led to strong astrogliosis accompanied by microgliosis and demyelination in C57BL/6 wild-type mice. Ablation of astrocytes in glial fibrillary acidic protein-thymidine kinase transgenic mice was associated with a failure of damaged myelin removal and a consecutive delay in remyelination. Despite oligodendrocyte death, myelin was still present, but ultrastructual investigations showed that the myelin structure was loosened and this damaged myelin did not protect axons. These alterations were associated with a decrease in microglial activation. Thus, our results show that astrocyte loss does not prevent myelin damage, but clearance of damaged myelin through recruitment of microglia is impaired. Further studies suggest that this process is regulated by the chemokine CXCL10. As a consequence of the delayed removal of myelin debris, remyelination and oligodendrocyte precursor cell proliferation were impaired. Experiments omitting the influence of myelin debris demonstrated an additional beneficial effect of astrocytes on oligodendrocyte regeneration during remyelination. In conclusion, these data demonstrate for the first time in vivo that astrocytes provide the signal environment that forms the basis for the recruitment of microglia to clear myelin debris, a process required for subsequent repair mechanisms. This is of great importance to understanding regenerative processes in demyelinating diseases such as multiple sclerosis.
Autoreactive Th1 and Th17 cells are believed to mediate the pathology of multiple sclerosis in the central nervous system (CNS). Their interaction with microglia and astrocytes in the CNS is crucial ...for the regulation of the neuroinflammation. Previously, we have shown that only Th1 but not Th17 effectors activate microglia. However, it is not clear which cells are targets of Th17 effectors in the CNS.
To understand the effects driven by Th17 cells in the CNS, we induced experimental autoimmune encephalomyelitis in wild-type mice and CD4
T cell-specific integrin α4-deficient mice where trafficking of Th1 cells into the CNS was affected. We compared microglial and astrocyte response in the brain and spinal cord of these mice. We further treated astrocytes with supernatants from highly pure Th1 and Th17 cultures and assessed the messenger RNA expression of neurotrophic factors, cytokines and chemokines, using real-time PCR. Data obtained was analyzed using the Kruskal-Wallis test.
We observed in α4-deficient mice weak microglial activation but comparable astrogliosis to that of wild-type mice in the regions of the brain populated with Th17 infiltrates, suggesting that Th17 cells target astrocytes and not microglia. In vitro, in response to supernatants from Th1 and Th17 cultures, astrocytes showed altered expression of neurotrophic factors, pro-inflammatory cytokines and chemokines. Furthermore, increased expression of chemokines in Th1- and Th17-treated astrocytes enhanced recruitment of microglia and transendothelial migration of Th17 cells in vitro.
Our results demonstrate the delicate interaction between T cell subsets and glial cells and how they communicate to mediate their effects. Effectors of Th1 act on both microglia and astrocytes whereas Th17 effectors preferentially target astrocytes to promote neuroinflammation.
Human bornavirus encephalitis is a severe and often fatal infection caused by variegated squirrel bornavirus 1 (VSBV-1) and Borna disease virus 1 (BoDV-1). We conducted a prospective study of ...bornavirus etiology of encephalitis cases in Germany during 2018-2020 by using a serologic testing scheme applied along proposed graded case definitions for VSBV-1, BoDV-1, and unspecified bornavirus encephalitis. Of 103 encephalitis cases of unknown etiology, 4 bornavirus infections were detected serologically. One chronic case was caused by VSBV-1 after occupational-related contact of a person with exotic squirrels, and 3 acute cases were caused by BoDV-1 in virus-endemic areas. All 4 case-patients died. Bornavirus etiology could be confirmed by molecular methods. Serologic testing for these cases was virus specific, discriminatory, and a practical diagnostic option for living patients if no brain tissue samples are available. This testing should be guided by clinical and epidemiologic suspicions, such as residence in virus-endemic areas and animal exposure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Current treatments for multiple sclerosis (MS) include immunomodulatory or immunosuppressive agents but no neuroprotective or regenerative therapy is available. From various animal models, we have ...learned that remyelination in the CNS is a potent neuroprotective mechanism. The knowledge about oligodendrocyte biology and the process of remyelination has greatly increased in recent years; however, the precise mechanisms are far from being understood. Although remyelination is, in principle, also possible in the diseased MS brain, it is not clear why it fails in many MS patients. The clinical trials performed so far either failed to show an effect or were insufficient in design. Thus, further knowledge about the molecular mechanisms of the repair processes and MS pathophysiology is required to achieve the ultimate goal of a neuroprotective and neuroregenerative treatment in MS.
Multiple Sclerosis (MS) is a chronic inflammatory, immune mediated disease of the central nervous system, with Relapsing Remitting MS (RRMS) being the most common type. Within the last years, the ...status of high disease activity (HDA) has become increasingly important for clinical decisions. Nevertheless, little is known about the incidence, the characteristics, and the current treatment of patients with RRMS and HDA in Germany. Therefore, this study aims to estimate the incidence of HDA in a German RRMS patient population, to characterize this population and to describe current drug treatment routines and further healthcare utilization of these patients.
A claims data analyses has been conducted, using a sample of the InGef Research Database that comprises data of approximately four million insured persons from around 70 German statutory health insurances (SHI). The study was conducted in a retrospective cohort design, including the years 2012-2016. Identification of RRMS population based on ICD-10 code (ICD-10-GM: G35.1). For identification of HDA, criteria from other studies as well as expert opinions have been used. Information on incidence, characteristics and current treatment of patients with RRMS and HDA was considered.
The overall HDA incidence within the RRMS population was 8.5% for 2016. It was highest for the age group of 0-19 years (29.4% women, 33.3% men) and lowest for the age group of ≥ 50 years (4.3% women, 5.6% men). Mean age of patients with RRMS and incident HDA was 38.4 years (SD: 11.8) and women accounted for 67.8%. Analyses of drug utilization showed that 82.4% received at least one disease-modifying drug (DMD) in 2016. A percentage of 49.8% of patients received drugs for relapse therapy. A share of 55% of RRMS patients with HDA had at least one hospitalization with a mean length of stay of 13.9 days (SD: 18.3 days) in 2016. The average number of outpatient physician contacts was 28.1 (SD: 14.0).
This study based on representative Germany-wide claims data from the SHI showed a high incidence of HDA especially within the young RRMS population. Future research should consider HDA as an important criterion for the quality of care for MS patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Microglia play a key role in the initiation and perpetuation of de- and remyelination because of their ability to present antigens and clear cell debris by phagocytosis. Different factors ...expressed or secreted by microglia seem to play an important role in regenerative processes. But it remains unclear which factors lead to a protective microglial phenotype and recent data indicate region-specific differences within the central nervous system (CNS) for both de-/remyelination and microglial response. In order to identify important factors that promote neuroprotection, we examined changes in microglial phenotypes in the cuprizone model. We undertook an extensive and detailed analysis of the expression of surface markers as well as cytokines, growth factors, and the phagocytosis activity of microglia. We found a pronounced increase of phagocytosis activity of microglia during demyelination associated with an upregulation of phagocytic receptors, from which TREM-2b was the most prominent. The expression of MHC II was only increased at the peak of demyelination but costimulatory molecules showed no significant changes. Interestingly, the proinflammatory cytokine TNF-α was upregulated while the anti-inflammatory cytokines IL-10 and TGF-ß remained unchanged. The growth factors IFG-1 and FGF-2, which were both suggested to promote remyelination, were increased during demyelination. Our findings characterise changes of microglial markers during de- and remyelination indicating that debris clearance mediated via TREM-2b plays a central role in the regulation of these processes. Microglial phagocytosis as well as production of TNF-α, IGF-1, and FGF-2 seems to be important factors for the creation of an environment promoting regeneration.
A broad spectrum of diseases is characterized by myelin abnormalities and/or oligodendrocyte pathology. In most, if not all, of these diseases, early activation of microglia occurs. Our knowledge ...regarding the factors triggering early microglia activation is, however, incomplete. In this study, we used the cuprizone model to investigate the temporal and causal relationship of oligodendrocyte apoptosis and early microglia activation. Genome-wide gene expression studies revealed the induction of distinct chemokines, among them Cxcl10, Ccl2, and Ccl3 in cuprizone-mediated oligodendrocyte apoptosis. Early microglia activation was unchanged in CCL2- and CCL3-deficient knockouts, but was significantly reduced in CXCL10-deficient mice, resulting in an amelioration of cuprizone toxicity at later time points. Subsequent in vitro experiments revealed that recombinant CXCL10 induced migration and a proinflammatory phenotype in cultured microglia, without affecting their phagocytic activity or proliferation. In situ hybridization analyses suggest that Cxcl10 mRNA is mainly expressed by astrocytes, but also oligodendrocytes, in short-term cuprizone-exposed mice. Our results show that CXCL10 actively participates in the initiation of microglial activation. These findings have implications for the role of CXCL10 as an important mediator during the initiation of neuroinflammatory processes associated with oligodendrocyte pathology.
Neuroborreliosis represents a relevant infectious disease and can cause a variety of neurological manifestations. Different stages and syndromes are described and atypical symptoms can result in ...diagnostic delay or misdiagnosis. The aim of this retrospective study was to define the pivotal neurological deficits in patients with neuroborreliosis that were the reason for admission in a hospital.
We retrospectively evaluated data of patients with neuroborreliosis. Only patients who fulfilled the diagnostic criteria of an intrathecal antibody production against Borrelia burgdorferi were included in the study.
Sixty-eight patients were identified with neuroborreliosis. Cranial nerve palsy was the most frequent deficit (50%) which caused admission to a hospital followed by painful radiculitis (25%), encephalitis (12%), myelitis (7%), and meningitis/headache (6%). In patients with a combination of deficits, back pain was the first symptom, followed by headache, and finally by cranial nerve palsy. Indeed, signs of meningitis were often found in patients with neuroborreliosis, but usually did not cause admission to a hospital. Unusual cases included patients with sudden onset paresis that were initially misdiagnosed as stroke and one patient with acute delirium. Cerebrospinal fluid (CSF) analysis revealed typical changes including elevated CSF cell count in all but one patient, a blood-CSF barrier dysfunction (87%), CSF oligoclonal bands (90%), and quantitative intrathecal synthesis of immunoglobulins (IgM in 74%, IgG in 47%, and IgA in 32% patients). Importantly, 6% of patients did not show Borrelia specific antibodies in the blood.
In conclusion, the majority of patients presented with typical neurological deficits. However, unusual cases such as acute delirium indicate that neuroborreliosis has to be considered in a wide spectrum of neurological diseases. CSF analysis is essential for a reliable diagnosis of neuroborreliosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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