Angelika Derksen

Sural sparing pattern discriminates Guillain–Barré syndrome from its mimics

Introduction: Electrodiagnostic features of demyelination are essential for establishing the diagnosis in demyelinating subtypes of Guillain‐Barré syndrome (GBS), but they may also occur in disorders that mimic GBS clinically. Information about their frequency in GBS mimics is sparse. Methods: Evaluation of electrodiagnostic features from 38 patients with suspected GBS in whom the diagnosis was later refuted (GBS mimics). Their diagnostic accuracy was analyzed by comparison with nerve conduction studies (NCS) from 73 confirmed GBS patients. Results: Disorders that mimicked GBS clinically at the time of hospital admission included other inflammatory, metabolic, toxic, or infectious neuropathies and spinal cord disorders. The sural sparing pattern was the most specific electrodiagnostic feature for demyelinating GBS. Conclusions: Common electrodiagnostic abnormalities in early demyelinating GBS do not usually exclude other rare differential diagnoses. An exception to this is the sural sparing pattern described here, which strongly supports the diagnosis of demyelinating GBS. Muscle Nerve 50: 780–784, 2014

A reliable in vitro model for studying peripheral nerve myelination in mouse.

The rat dorsal root ganglia (DRG) model is a long-standing in vitro model for analysis of myelination in the peripheral nervous system. For performing systematic, high throughput analysis with transgenic animals, a simplified BL6 mouse protocol is indispensable. Here we present a stable and reliable protocol for myelinating co-cultures producing a high myelin ratio using cells from C57BL/6 mice. As an easy accessible and operable method, Sudan staining proved to be efficient in myelin detection for fixed cultures. Green fatty acid stain turned out to be highly reliable for analysis of the dynamic biological processes of myelination in vital cultures. Once myelinated we were able to induce demyelination by the addition of forskolin into the model system. In addition, we provide an optimised rat DRG protocol with significantly improved myelin ratio and a comparison of the protocols presented. Our results strengthen the value of ex vivo myelination models in neurobiology.

Promoting Myelination in an In Vitro Mouse Model of the Peripheral Nerve System: The Effect of Wine Ingredients

Protective properties of moderate wine consumption against cancers, cardiovascular, metabolic and degenerative diseases have been reported in various clinical studies. Here, we analysed the effect of red wine (RW) and white wine (WW) on myelination using an in vitro embryonic co-culture mouse model. The total amount of myelin was found to be significantly increased after RW and WW treatment, while only RW significantly increased the number of internodes. Both types of wine increased rat Schwann cell- (rSC) expression of the NAD+-dependent deacetylase sirtuin-two-homolog 2 (Sirt2), a protein known to be involved in myelination. Detailed chemical analysis of RW revealed a broad spectrum of anthocyanins, piceids, and phenolics, including resveratrol (RSV). In our assay system RSV in low concentrations induced myelination. Furthermore RSV raised intracellular glutathione concentrations in rSCs and in co-cultures and therefore augmented antioxidant capacity. We conclude that wine promotes myelination in a rodent in vitro model by controlling intracellular metabolism and SC plasticity. During this process, RSV exhibits protective properties; however, the fostering effect on myelinaton during exposure to wine appears to be a complex interaction of various compounds.

Antiglycine receptor-related stiff limb syndrome in a patient with chronic lymphocytic leukaemia

We report a 61-year-old man presenting with rapidly progressive stiffness and painful muscle spasms in the lower extremity muscles. The patient was diagnosed with chronic lymphocytic leukaemia (CLL) approximately a year before symptom onset. Electromyography displayed continuous motor unit activity and immunocytochemistry showed a positive staining for antiglycine receptor (anti-GlyR) antibodies. The clinical course was complicated by autonomic instability and cardiac arrest, but stabilised under continuous therapy with plasma exchange and symptomatic treatment with baclofen and clonazepam. Anti-GlyR antibodies induce rare, but severe, variants of stiff person syndrome that can be of paraneoplastic origin and life threatening due to autonomic dysfunction.

Fingolimod promotes peripheral nerve regeneration via modulation of lysophospholipid signaling.

BackgroundThe lysophospholipids sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are pleiotropic signaling molecules with a broad range of physiological functions. Targeting the S1P1 receptor on lymphocytes with the immunomodulatory drug fingolimod has proven effective in the treatment of multiple sclerosis. An emerging body of experimental evidence points to additional direct effects on cells of the central and peripheral nervous system. Furthermore, fingolimod has been reported to reduce LPA synthesis via inhibition of the lysophospholipase autotaxin. Here we investigated whether modulation of particular signaling aspects of S1P as well as LPA by fingolimod might propagate peripheral nerve regeneration in vivo and independent of its anti-inflammatory potency.MethodsSciatic nerve crush was performed in wildtype C57BL/6, in immunodeficient Rag1−/− and Foxn1−/− mice. Analyses were based on walking track analysis and electrophysiology, histology, and cAMP formation. Quantification of different LPA species was performed by liquid chromatography coupled to tandem mass spectrometry. Furthermore, functional consequences of autotaxin inhibition by the specific inhibitor PF-8380 and the impact of fingolimod on early cytokine release in the injured sciatic nerve were investigated.ResultsClinical and electrophysiological measures indicated an improvement of nerve regeneration under fingolimod treatment that is partly independent of its anti-inflammatory properties. Fingolimod treatment correlated with a significant elevation of axonal cAMP, a crucial factor for axonal outgrowth. Additionally, fingolimod significantly reduced LPA levels in the injured nerve. PF-8380 treatment correlated with improved myelin thickness. Sciatic nerve cytokine levels were not found to be significantly altered by fingolimod treatment.ConclusionsOur findings provide in vivo evidence for direct effects of fingolimod on cells of the peripheral nervous system that may propagate nerve regeneration via a dual mode of action, differentially affecting axonal outgrowth and myelination by modulating relevant aspects of S1P and LPA signaling.

Clinical improvement precedes lesion size regression in a severe case of acute disseminated encephalomyelitis

Here, we present a case of a severe acute disseminated encephalomyelitis (ADEM) of a 42-year-old male patient. The diagnosis was established after brain biopsy and due to acutely evolving encephalopathy occurring in the context of atypical Mycoplasma pneumoniae (MP). We analysed the prominent MRI white matter lesions using a three-dimensional algorithm as cutting-edge technique to study morphological abnormalities and correlated them to the clinical condition of the patient. We found a discrepancy between the lesion size and the clinical deficits of the patient, actually the clinical improvement antedated the regression of the white matter lesions.

Schwann cells promote post-traumatic nerve inflammation and neuropathic pain through MHC class II

The activation of T helper cells requires antigens to be exposed on the surface of antigen presenting cells (APCs) via MHC class II (MHC-II) molecules. Expression of MHC-II is generally limited to professional APCs, but other cell types can express MHC-II under inflammatory conditions. However, the importance of these conditional APCs is unknown. We and others have previously shown that Schwann cells are potentially conditional APCs, but the functional relevance of MHC-II expression by Schwann cells has not been studied in vivo. Here, we conditionally deleted the MHC-II β-chain from myelinating Schwann cells in mice and investigated how this influenced post-traumatic intraneural inflammation and neuropathic pain using the chronic constriction injury (CCI) model. We demonstrate that deletion of MHC-II in myelinating Schwann cells reduces thermal hyperalgesia and, to a lesser extent, also diminishes mechanical allodynia in CCI in female mice. This was accompanied by a reduction of intraneural CD4+ T cells and greater preservation of preferentially large-caliber axons. Activation of T helper cells by MHC-II on Schwann cells thus promotes post-traumatic axonal loss and neuropathic pain. Hence, we provide experimental evidence that Schwann cells gain antigen-presenting function in vivo and modulate local immune responses and diseases in the peripheral nerves.

Neuronal ADAM10 Promotes Outgrowth of Small-Caliber Myelinated Axons in the Peripheral Nervous System.

Abstract The regulation of myelination and axonal outgrowth in the peripheral nervous system is controlled by a complex signaling network involving various signaling pathways. Members of the A Disintegrin And Metalloproteinase (ADAM) family are membrane-anchored proteinases with both proteolytic and disintegrin characteristics that modulate the function of signaling molecules. One family member, ADAM17, is known to influence myelination by cleaving and thus regulating one of the key signals, neuregulin-1, which controls peripheral nervous system myelination. A similar function for ADAM10 had been suggested by previous in vitro studies. Here, we assessed whether ADAM10 exerts a similar function in vivo and deleted ADAM10 in a cell type–specific manner in either neurons or Schwann cells. We found that ADAM10 is not required in either Schwann cells or neurons for normal myelination during development or for remyelination after injury. Instead, ADAM10 is required specifically in neurons for the outgrowth of myelinated small-fiber axons in vitro and after injury in vivo. Thus, we report for the first time a neuron-intrinsic function of ADAM10 in axonal regeneration that is distinct from that of the related protein family member ADAM17 and that may have implications for targeting ADAM function in nervous system diseases.

EP 12. Fingolimod promotes nerve regeneration by modulating Lysophospholipid signaling

The lysophospholipids sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) are pleiotropic signaling molecules with a broad range of physiological functions. Targeting the S1P 1 receptor on lymphocytes with the immunomodulatory drug fingolimod has proven effective in the treatment of multiple sclerosis. An emerging body of experimental evidence points to additional direct effects on cells of the central and peripheral nervous system. Furthermore, fingolimod has been reported to reduce LPA synthesis via inhibition of the lysophospholipase autotaxin. Here we investigated whether modulation of particular signaling aspects of S1P as well as LPA by fingolimod might propagate peripheral nerve regeneration in vivo and independent of its anti-inflammatory potency. To distinguish potential direct nerve specific effects from the established immunosuppressive action of fingolimod, we performed sciatic nerve crush in wildtype C57BL/6 as well as in immunodeficient Rag 1 - / - and Foxn 1 - / - mice. Analyses were based on walking track analysis and electrophysiology, histology, cAMP formation as well as oxidative stress assessment by dinitrophenyl-labeling of free protein carbonyls. Quantification of different LPA species was performed by liquid chromatography coupled to tandem mass spectrometry. Furthermore, functional consequences of LPA level reduction by the autotaxin inhibitor PF-8380 were investigated. Clinical, electrophysiological and histological measures indicated an improvement of nerve regeneration under fingolimod treatment that is partly independent of its anti-inflammatory properties. Fingolimod induced an elevation of axonal cAMP, a crucial factor for axonal outgrowth. Consistently, immunohistochemistry indicated S1P 1 receptor internalization in cells of the sciatic nerve. Additionally, fingolimod attenuated oxidative tissue damage and significantly reduced LPA levels in the injured nerve. PF-8380 induced reduction of LPA levels correlated with improved myelin thickness. Collectively, our work demonstrates that modulation of lysophospholipid signaling in the peripheral nervous system by fingolimod may enhance nerve regeneration by acting on multiple molecular and cellular levels and partly independent of its anti-inflammatory effects. In addition to the established role of fingolimod as a modulator of S1P receptor mediated signaling, the inhibition of LPA synthesis may represent a yet unrecognized mechanism that contributes to the presumptive remyelinating effect of fingolimod.

Schwann cell locomotion during peripheral nerve inflammation

ischemia in WT and caspase-1−/− mice. A different group of mice was treated with the specific caspase-1 inhibitor z-YVAD-FMK or control. We analyzed differential cell percentages of lymphocyte and monocyte subpopulations at 6 h and 3 days after experimental stroke by flow cytometry of blood and spleen. Serum cytokine levels were analyzed by ELISA and cellular activation after stroke detected by intracellular cytokine assays. Pyroptosis as a cause of immune cell deathwasmeasured by intracellular caspase-1 labeling and membrane disruption by 7-AAD. Results: An increase in caspase-1 activation was detected after 3 days of stroke in splenic monocytes and lymphocytes. However, caspase-1 activation in circulating leukocytes was evident only in lymphocytes but not in monocytes. Furthermore, differential blood cell counts were unaffected by caspase-1 expression after stroke. Additionally, we detected an enhanced expression of intracellular inflammatory cytokines in monocytes during the acute phase after stroke. This differential activation of caspase-1 in leukocyte subpopulations was associated with enhanced inflammatory cytokine concentrations. Genetic as well as pharmacological disruption of caspase-1 signaling abrogated leukocyte pyroptosis and the post-stroke inflammatory reaction. Conclusion: We revealed caspase-1 as a key molecule in the regulation of post-stroke immune cell death and activation. It induces early immune activation as well as delayed pyroptotic immune cell death, thereby, suggesting a novel and comprehensive molecular target to treat the complex immune dysregulation after acute brain injuries.