Interleukin-17 and Th17 Lymphocytes Directly Impair Motoneuron Survival of Wildtype and FUS-ALS Mutant Human iPSCs

Amyotrophic lateral sclerosis (ALS) is a progressive disease leading to the degeneration of motor neurons (MNs). Neuroinflammation is involved in the pathogenesis of ALS; however, interactions of specific immune cell types and MNs are not well studied. We recently found a shift toward T helper (Th)1/Th17 cell-mediated, pro-inflammatory immune responses in the peripheral immune system of ALS patients, which positively correlated with disease severity and progression. Whether Th17 cells or their central mediator, Interleukin-17 (IL-17), directly affects human motor neuron survival is currently unknown. Here, we evaluated the contribution of Th17 cells and IL-17 on MN degeneration using the co-culture of iPSC-derived MNs of fused in sarcoma (FUS)-ALS patients and isogenic controls with Th17 lymphocytes derived from ALS patients, healthy controls, and multiple sclerosis (MS) patients (positive control). Only Th17 cells from MS patients induced severe MN degeneration in FUS-ALS as well as in wildtype MNs. Their main effector, IL-17A, yielded in a dose-dependent decline of the viability and neurite length of MNs. Surprisingly, IL-17F did not influence MNs. Importantly, neutralizing IL-17A and anti-IL-17 receptor A treatment reverted all effects of IL-17A. Our results offer compelling evidence that Th17 cells and IL-17A do directly contribute to MN degeneration.

Clobetasol promotes neuromuscular plasticity in mice after motoneuronal loss via sonic hedgehog signaling, immunomodulation and metabolic rebalancing

Motoneuronal loss is the main feature of amyotrophic lateral sclerosis, although pathogenesis is extremely complex involving both neural and muscle cells. In order to translationally engage the sonic hedgehog pathway, which is a promising target for neural regeneration, recent studies have reported on the neuroprotective effects of clobetasol, an FDA-approved glucocorticoid, able to activate this pathway via smoothened. Herein we sought to examine functional, cellular, and metabolic effects of clobetasol in a neurotoxic mouse model of spinal motoneuronal loss. We found that clobetasol reduces muscle denervation and motor impairments in part by restoring sonic hedgehog signaling and supporting spinal plasticity. These effects were coupled with reduced pro-inflammatory microglia and reactive astrogliosis, reduced muscle atrophy, and support of mitochondrial integrity and metabolism. Our results suggest that clobetasol stimulates a series of compensatory processes and therefore represents a translational approach for intractable denervating and neurodegenerative disorders.

Perisynaptic Schwann cells phagocytose nerve terminal debris in a mouse model of Guillain-Barré syndrome

In mouse models of acute motor axonal neuropathy, anti-ganglioside antibodies (AGAbs) bind to motor axons, notably the distal nerve, and activate the complement cascade. While complement activation is well studied in this model, the role of inflammatory cells is unknown. Herein we aimed to investigate the contribution of phagocytic cells including macrophages, neutrophils and perisynaptic Schwann cells (pSCs) to distal nerve pathology. To observe this, we first created a subacute injury model of sufficient duration to allow inflammatory cell recruitment. Mice were injected intraperitoneally with an anti-GD1b monoclonal antibody that binds strongly to mouse motor nerve axons. Subsequently, mice received normal human serum as a source of complement. Dosing was titrated to allow humane survival of mice over a period of 3 days, yet still induce the characteristic neurological impairment. Behaviour and pathology were assessed in vivo using whole-body plethysmography and post-sacrifice by immunofluorescence and flow cytometry. ex vivo nerve-muscle preparations were used to investigate the acute phagocytic role of pSCs following distal nerve injury. Following complement activation at distal intramuscular nerve sites in the diaphragm macrophage localisation or numbers are not altered, nor do they shift to a pro- or anti-inflammatory phenotype. Similarly, neutrophils are not significantly recruited. Instead, ex vivo nerve-muscle preparations exposed to AGAb plus complement reveal that pSCs rapidly become phagocytic and engulf axonal debris. These data suggest that pSCs, rather than inflammatory cells, are the major cellular vehicle for axonal debris clearance following distal nerve injury, in contrast to larger nerve bundles where macrophage-mediated clearance predominates.

Antiviral Immune Response as a Trigger of FUS Proteinopathy in Amyotrophic Lateral Sclerosis

Mutations in the FUS gene cause familial amyotrophic lateral sclerosis (ALS-FUS). In ALS-FUS, FUS-positive inclusions are detected in the cytoplasm of neurons and glia, a condition known as FUS proteinopathy. Mutant FUS incorporates into stress granules (SGs) and can spontaneously form cytoplasmic RNA granules in cultured cells. However, it is unclear what can trigger the persistence of mutant FUS assemblies and lead to inclusion formation. Using CRISPR/Cas9 cell lines and patient fibroblasts, we find that the viral mimic dsRNA poly(I:C) or a SG-inducing virus causes the sustained presence of mutant FUS assemblies. These assemblies sequester the autophagy receptor optineurin and nucleocytoplasmic transport factors. Furthermore, an integral component of the antiviral immune response, type I interferon, promotes FUS protein accumulation by increasing FUS mRNA stability. Finally, mutant FUS-expressing cells are hypersensitive to dsRNA toxicity. Our data suggest that the antiviral immune response is a plausible second hit for FUS proteinopathy.

Identification and therapeutic rescue of autophagosome and glutamate receptor defects in C9ORF72 and sporadic ALS neurons

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease with diverse etiologies. Therefore, the identification of common disease mechanisms and therapeutics targeting these mechanisms could dramatically improve clinical outcomes. To this end, we developed induced motor neuron (iMN) models from C9ORF72 and sporadic ALS (sALS) patients to identify targets that are effective against these types of cases, which together comprise ~90% of patients. We find that iMNs from C9ORF72 and several sporadic ALS patients share two common defects - impaired autophagosome formation and the aberrant accumulation of glutamate receptors. Moreover, we show that an anticoagulation-deficient form of activated protein C, 3K3A-APC, rescues these defects in both C9ORF72 and sporadic ALS iMNs. As a result, 3K3A-APC treatment lowers C9ORF72 dipeptide repeat protein (DPR) levels, restores nuclear TDP-43 localization, and rescues the survival of both C9ORF72 and sporadic ALS iMNs. Importantly, 3K3A-APC also lowers glutamate receptor levels and rescues proteostasis in vivo in C9ORF72 gain- and loss-of-function mouse models. Thus, motor neurons from C9ORF72 and at least a subset of sporadic ALS patients share common, early defects in autophagosome formation and glutamate receptor homeostasis and a single therapeutic approach may be efficacious against these disease processes.

Motor neuron loss and neuroinflammation in a model of α-synuclein-induced neurodegeneration

Mechanisms underlying α-synuclein (αSyn) mediated neurodegeneration are poorly understood. Intramuscular (IM) injection of αSyn fibrils in human A53T transgenic M83+/- mice produce a rapid model of α-synucleinopathy with highly predictable onset of motor impairment. Using varying doses of αSyn seeds, we show that αSyn-induced phenotype is largely dose-independent. We utilized the synchrony of this IM model to explore the temporal sequence of αSyn pathology, neurodegeneration and neuroinflammation. Longitudinal tracking showed that while motor neuron death and αSyn pathology occur within 2 months post IM, astrogliosis appears at a later timepoint, implying neuroinflammation is a consequence, rather than a trigger, in this prionoid model of synucleinopathy. Initiating at 3 months post IM, immune activation dominates the pathologic landscape in terminal IM-seeded M83+/- mice, as revealed by unbiased transcriptomic analyses. Our findings provide insights into the role of neuroinflammation in αSyn mediated proteostasis and neurodegeneration, which will be key in designing potential therapies.

Lipopolysaccharide-induced inflammation does not alter muscle spindle afferent mechanosensation or sensory integration in the spinal cord of adult mice

Inflammation is known to alter nervous system function, but its effect on muscle spindle afferent mechanosensation and sensory integration in the spinal cord has not been well studied. We tested the hypothesis that systemic inflammation induced by an intraperitoneal injection of the endotoxin lipopolysaccharide (LPS; 7.5 × 105 endotoxin units/kg 18 h before experiment) would alter muscle spindle afferent mechanosensation and spinal cord excitability to Group Ia input in male and female adult C57Bl/6 mice. LPS injection caused a systemic immune response, evidenced by decreased white blood cell, monocyte, and lymphocyte concentrations in the blood, increased blood granulocyte concentration, and body weight loss. The immune response in both sexes was qualitatively similar. We used an in vitro muscle-nerve preparation to assay muscle spindle afferent response to stretch and vibration. LPS injection did not significantly change the response to stretch or vibration, with the exception of small decreases in the ability to entrain to high-frequency vibration in male mice. Similarly, LPS injection did not alter spinal cord excitability to Group Ia muscle spindle afferent input as measured by the Hoffman's reflex test in anesthetized mice (100 mg/kg ketamine, 10 mg/kg xylazine). Specifically, there were no changes in M or H wave latencies nor in the percentage of motor neurons excited by electrical afferent stimulation (Hmax /Mmax ). Overall, we found no major alterations in muscle proprioceptor function or sensory integration following exposure to LPS at a dose and time course that causes changes in nociceptor function and central processing.

Spinal cord injury effectively ameliorated by neuroprotective effects of rosmarinic acid

OBJECTIVE

Pathophysiology of spinal cord injury (SCI) causes primary and secondary effects leading to loss of neuronal function. The aim of the present study was to investigate the role of rosmarinic acid (RA) in protection against SCI.

METHODS

The experimental study was carried out in male wistar rats categorized into three groups. Group I - sham operated rats; Group II - SCI; Group III - SCI followed by RA treatment (10 mg/kg). The spinal tissues after treatment schedule were analyzed for oxidative stress status through determination of reactive oxygen species (ROS), lipid peroxidation, protein damage (carbonyl and sulfhydryl contents), and antioxidant enzyme activities. The expression of oxidative stress factors NF-κB and Nrf-2 was determined by Western blot analysis. Further pro-inflammatory cytokines (TNF-α, IL-6, MCP-1, and IL-1β) were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results show that treatment with RA significantly enhances the antioxidant status and decrease the oxidative stress in wistar rats post-SCI. RA effectively ameliorated inflammatory mechanisms by downregulation of NF-κB and pro-inflammatory cytokines post-SCI.

CONCLUSION

The study demonstrates for the first time on the role of RA in protecting the spinal cord from injury and demonstrates its neuroprotection in wistar rats.

Highly immunoreactive IgG antibodies directed against a set of twenty human proteins in the sera of patients with amyotrophic lateral sclerosis identified by protein array

Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disorder, is characterized by the progressive and selective loss of upper and lower motor neurons. Diagnosis of this disorder is based on clinical assessment, and the average survival time is less than 3 years. Injections of IgG from ALS patients into mice are known to specifically mark motor neurons. Moreover, IgG has been found in upper and lower motor neurons in ALS patients. These results led us to perform a case-control study using human protein microarrays to identify the antibody profiles of serum samples from 20 ALS patients and 20 healthy controls. We demonstrated high levels of 20 IgG antibodies that distinguished the patients from the controls. These findings suggest that a panel of antibodies may serve as a potential diagnostic biomarker for ALS.

Inflammation and neurovascular changes in amyotrophic lateral sclerosis

Neuroinflammation in now established as an important factor in the pathogenesis of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). At various time points, astrocytes and microglia are markedly activated, either producing neuroprotective or pro-inflammatory molecules, which can decrease or increase the rate of primary motor neuron degeneration respectively. Recent research has shown that this neuroinflammatory component is affected by the peripheral immune system; T lymphocytes in particular are able to cross into the brain and spinal cord parenchyma, where they interact with resident microglia, either inducing them to adopt an M1 (cytotoxic) or M2 (protective) phenotype, depending on the stage of disease. Clearly understanding the changes that occur to allow the interaction between peripheral and central immune responses will be essential in any attempt to manipulate the disease process via neuroinflammatory mechanisms. However, our understanding of the endothelial changes, which facilitate the infiltration of peripheral immune cells into the brain and spinal cord, is still in its infancy. There are suggestions, though, of up-regulation of cellular adhesion molecules, which are able to arrest circulating leukocytes and facilitate diapedesis into the brain parenchyma. In addition, tight junction proteins appear to be down-regulated, leading to an increase in vascular permeability, an effect that is amplified by vascular damage late in the disease process. This review summarises our current knowledge regarding neuroinflammation, peripheral immune involvement, and endothelial changes in ALS. This article is part of a Special Issue entitled 'Neuroinflammation in neurodegeneration and neurodysfunction'.

Immune cell-mediated neuroprotection is independent of estrogen action through estrogen receptor-alpha

It has been well documented that both estrogen and immune cells (CD4+ T cells) mediate neuroprotection in the mouse facial nerve axotomy model. Estrogen has been shown to play an important role in regulating the immune response. However, it is unclear whether immune cell-mediated neuroprotection is dependent on estrogen signaling. In this study, using FACS staining, we confirmed that the majority of CD4+ T cells express high levels of estrogen receptor-alpha (ERα), suggesting that CD4+ T cell-mediated neuroprotection may be modulated by estrogen signaling. We previously found that immunodeficient Rag-2KO mice showed a significant increase in axotomy-induced facial motoneuron death compared to immunocompetent wild-type mice. Therefore, we investigated axotomy-induced facial motoneuron loss in immunodeficient Rag-2KO mice that received 17β-estradiol treatment or adoptive transfer of immune cells from mice lacking functional ERα. Our results indicate that while estradiol treatment failed to rescue facial motoneurons from axotomy-induced cell death in Rag-2KO mice, immune cells lacking ERα successfully restored facial motoneuron survival in Rag-2 KO mice to a wild-type level. Collectively, we concluded that CD4+ T cell-mediated neuroprotection is independent of estrogen action through ERα.

Neuroinflammation modulates distinct regional and temporal clinical responses in ALS mice

An inflammatory response is a pathological hallmark of amyotrophic lateral sclerosis (ALS), a relentless and devastating degenerative disease of motoneurons. This response is not simply a late consequence of motoneuron degeneration, but actively contributes to the balance between neuroprotection and neurotoxicity; initially infiltrating lymphocytes and microglia slow disease progression, while later, they contribute to the acceleration of disease. Since motor weakness begins in the hindlimbs of ALS mice and only later involves the forelimbs, we determined whether differential protective versus injurious inflammatory responses in the cervical and lumbar spinal cords explained the temporally distinct clinical disease courses between the limbs of these mice. Densitometric evaluation of immunohistochemical sections and quantitative RT-PCR (qRT-PCR) demonstrated that CD68 and CD11c were differentially increased in their spinals cords. qRT-PCR revealed that protective and anti-inflammatory factors, including BDNF, GDNF, and IL-4, were increased in the cervical region compared with the lumbar region. In contrast, the toxic markers TNF-α, IL-1β and NOX2 were not different between ALS mice cervical and lumbar regions. T lymphocytes were observed infiltrating lumbar spinal cords of ALS mice prior to the cervical region; mRNA levels of the transcription factor gata-3 (Th2 response) were differentially elevated in the cervical cord of ALS mice whereas t-bet (Th1 response) was increased in the lumbar cord. These results reinforce the important balance between specific protective/injurious inflammatory immune responses in modulating clinical outcomes and suggest that the delayed forelimb motor weakness in ALS mice is partially explained by augmented protective responses in the cervical spinal cords.

Acute transverse myelitis and acute motor axonal neuropathy developed after vaccinations against seasonal and 2009 A/H1N1 influenza

Acute transverse myelitis (ATM) has been described as an uncommon complication of vaccinations and is rarely accompanied by inflammatory peripheral neuropathy. We report a case of a 77-year-old woman who developed ATM and acute motor axonal neuropathy (AMAN) following vaccinations against seasonal and 2009 A/H1N1 influenza. She manifested ophthalmoplegia, quadriparesis and sensory impairment. MR imaging showed a longitudinally-extensive spinal cord lesion, and nerve conduction study revealed motor axonal polyneuropathy. Despite prompt treatment, her symptoms poorly recovered. While concurrent ATM and AMAN may suggest the presence of a common antigen, their scarcity indicates the importance of other factors causing immunologic disruptions.

Absence of IFNγ expression induces neuronal degeneration in the spinal cord of adult mice

BACKGROUND

Interferon gamma (IFNγ) is a pro-inflammatory cytokine, which may be up-regulated after trauma to the peripheral or central nervous system. Such changes include reactive gliosis and synaptic plasticity that are considered important responses to the proper regenerative response after injury. Also, IFNγ is involved in the upregulation of the major histocompatibility complex class I (MHC class I), which has recently been shown to play an important role in the synaptic plasticity process following axotomy. There is also evidence that IFNγ may interfere in the differentiation and survival of neuronal cells. However, little is known about the effects of IFNγ absence on spinal cord neurons after injury.

METHODS

We performed a unilateral sciatic nerve transection injury in C57BL/6J (wild type) and IFNγ-KO (mutant) mice and studied motoneuron morphology using light and electron microscopy. One week after the lesion, mice from both strains were sacrificed and had their lumbar spinal cords processed for histochemistry (n = 5 each group) and transmission electron microscopy (TEM, n = 5 each group). Spinal cord sections from non-lesioned animals were also used to investigate neuronal survival and the presence of apoptosis with TUNEL and immunohistochemistry.

RESULTS

We find that presumed motoneurons in the lower lumbar ventral horn exhibited a smaller soma size in the IFNγ-KO series, regardless of nerve lesion. In plastic embedded sections stained with toluidine blue, the IFNγ-KO mice demonstrated a greater proportion of degenerating neurons in the ventral horn when compared to the control series (p < 0.05). Apoptotic death is suggested based on TUNEL and caspase 3 immunostaining. A sciatic nerve axotomy did not further aggravate the neuronal loss. The cellular changes were supported by electron microscopy, which demonstrated ventral horn neurons exhibiting intracellular vacuoles as well as degenerating nuclei and cytoplasm in the IFNγ-KO mice. Adjacent glial cells showed features suggestive of phagocytosis. Additional ultrastructural studies showed a decreased number of pre-synaptic terminals apposing to motoneurons in mutant mice. Nevertheless, no statistical difference regarding the input covering could be detected among the studied strains.

CONCLUSION

Altogether, these results suggest that IFNγ may be neuroprotective and its absence results in neuronal death, which is not further increased by peripheral axotomy.

Phenotype of CD4+ T cell subsets that develop following mouse facial nerve axotomy

We have previously shown that CD4(+) T helper (Th) 2 cells, but not Th1 cells, participate in the rescue of mouse facial motoneurons (FMN) from axotomy-induced cell death. Recently, a number of other CD4(+) T cell subsets have been identified in addition to the Th1 and Th2 effector subsets, including Th17, inducible T regulatory type 1 (Tr1), and naturally thymus-born Foxp3(+) regulatory (Foxp3(+) Treg) cells. These subsets regulate the nature of a T cell-mediated immune response. Th1 and Th17 cells are pro-inflammatory subsets, while Th2, Tr1, and Foxp3(+) Treg cells are anti-inflammatory subsets. Pro-inflammatory responses in the central nervous system are thought to be neurodestructive, while anti-inflammatory responses are considered neuroprotective. However, it remains to be determined if another CD4(+) T cell subset, other than the Th2 cell, develops after peripheral nerve injury and participates in FMN survival. In the present study, we used FACS analysis to determine the temporal frequency of Th1, Th17, Th2, Tr1 and Foxp3(+) Treg CD4(+) T cell subset development in C57BL/6 wild type mice after facial nerve transection at the stylomastoid foramen in the mouse. The results indicate that all of the known CD4(+) T cell subsets develop and expand in number within the draining lymph node, with a peak in number primarily at 7 days postoperative (dpo), followed by a decline at 9 dpo. In addition to the increase in subset frequency over time, FACS analysis of individual cells showed that the level of cytokine expressed per cell also increased for interferon-gamma (IFN-gamma), interleukin (IL)-10 and IL-17, but not IL-4. Additional control double-cytokine labeling experiments were done which indicate that, at 7dpo, the majority of cells indeed have committed to a specific phenotype and express only 1 cytokine. Collectively, our findings indicate for the first time that there is no preferential activation and expansion of any single CD4(+) T cell subset after peripheral nerve injury but, rather, that both pro-inflammatory and anti-inflammatory CD4(+) T cells develop.

Acquired neuromyotonia in childhood: case report and review

Recently characterized as an immune-mediated channelopaty, Isaacs' syndrome (also known as acquired neuromyotonia) was first described in 1961 in two men with persistent, generalized muscle stiffness, in addition to spontaneous, rapid discharges of motor-unit potentials on electromyography. In the peripheral nervous system, antibodies targeted to voltage-gated potassium channels induce hyperexcitability of motor axons, resulting in signs of muscle stiffness or of pseudomyotonia. A spontaneous burst of single motor-unit activity, and myokymic and neuromyotonic discharges, are the most characteristic features found in electromyography studies. This report describes Isaacs' syndrome in a child, in whom the diagnosis was made by clinical features of acquired, spontaneous muscle overactivity and typical electromyographic findings.

Microglia in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disorder that results in the selective death of motor neurons in the central nervous system. This progressive motor neuron degeneration leads to death of the patient on average three to five years after onset of the disease. To date, no therapy is available. Many hypotheses have been formulated to explain the selective degeneration of motor neurons. One of the most studied hypotheses is the putative role of the inflammatory response that accompanies motor neuron death. The proliferation of microglia and astrocytes has been considered to be a secondary phenomenon, but recently, evidence is accumulating in favour of a contributory role of the non-neuronal cell populations to the pathogenesis of the disease. In this review, we will introduce the characteristics of microglial cells in the central nervous system. We will summarize the evidence of the expansion and the activation of the microglial cell population that accompanies motor neuron degeneration. Finally, an overview will be given of the different therapeutic strategies that targeted the inflammatory process in amyotrophic lateral sclerosis.

Current management options in myasthenia gravis

Myasthenia gravis has changed from being a frequently fatal condition with a reputation little better than motor neuron disease to a generally treatable condition over the previous century. However, the chronic, largely immunosuppressive treatment comes with the major problems of very slow response and of treatment-induced morbidity and mortality. -Myasthenia gravis is a model autoimmune disease of a model physiologic structure, so is well placed for trials of novel treatments with ramifications for autoimmunity generally. There are also good animal models, so specific approaches to reinduction of tolerance can be tested. Hope of future revolutions in treatment should not hinder efforts to better understand currently available therapies and a concerted approach to ameliorate the side effects of treatment.

Plasmapheresis for chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disorder characterized by progressive or relapsing symmetrical motor or sensory symptoms and signs in more than one limb, developing over at least 2 months. It may cause prolonged periods of disability and even death. Evidence from trials suggests that plasma exchange provides significant short-term benefit in about two thirds of patients with chronic inflammatory demyelinating polyradiculoneuropathy. This review evaluates the role of plasmapheresis in CIDP.

Immune cell involvement in dorsal root ganglia and spinal cord after chronic constriction or transection of the rat sciatic nerve

Chronic constriction injury (CCI) of the sciatic nerve in rodents produces mechanical and thermal hyperalgesia and is a common model of neuropathic pain. Here we compare the inflammatory responses in L4/5 dorsal root ganglia (DRGs) and spinal segments after CCI with those after transection and ligation at the same site. Expression of ATF3 after one week implied that 75% of sensory and 100% of motor neurones had been axotomized after CCI. Macrophage invasion of DRGs and microglial and astrocytic activation in the spinal cord were qualitatively similar but quantitatively distinct between the lesions. The macrophage and glial reactions around neurone somata in DRGs and ventral horn were slightly greater after transection than CCI while, in the dorsal horn, microglial activation (using markers OX-42(for CD11b) and ED1(for CD68)) was greater after CCI. In DRGs, macrophages positive for OX-42(CD11b), CD4, MHC II and ED1(CD68) more frequently formed perineuronal rings beneath the glial sheath of ATF3+ medium to large neurone somata after CCI. There were more invading MHC II+ macrophages lacking OX-42(CD11b)/CD4/ED1(CD68) after transection. MHC I was expressed in DRGs and in spinal sciatic territories to a similar extent after both lesions. CD8+ T-lymphocytes aggregated to a greater extent both in DRGs and the dorsal horn after CCI, but in the ventral horn after transection. This occurred mainly by migration, additional T-cells being recruited only after CCI. Some of these were probably CD4+. It appears that inflammation of the peripheral nerve trunk after CCI triggers an adaptive immune response not seen after axotomy.

Enhanced visualization of axonopathy in EAE using thy1-YFP transgenic mice

It is widely accepted that chronic disabilities in multiple sclerosis (MS) patients are due in part to neuronal damage. The central aim of this study was to characterize axonal disruption in the spinal cord of mice with myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-EAE), a model of progressive MS. To accomplish this goal, we induced MOG-EAE in thy1-yellow fluorescent (thy-YFP)-transgenic mice in which all spinal motorneurons express the YFP reporter protein. We demonstrate that a build-up of YFP fluorescence occurs in profiles reminiscent of tortuous fragmented axons and axonal spheroids/globules as seen in various neurodegenerative/neuroinflammatory diseases. Approximately two-thirds of these damaged axons were decorated by the monoclonal antibody SMI 32, which recognizes hypophosphorylated neurofilament-H (hypoP-NF-H), an established marker of CNS axonal pathology. Unexpectedly, one third of damaged axons were hypoP-NF-H negative but could be visualized by their expression of the YFP transgene, whilst the remaining profiles were hypoP-NF-H positive but did not exhibit YFP fluorescence. Thus, using YFP transgenic mice in conjunction with hypoP-NF-H immunoreactivity provides a more comprehensive depiction of axonopathy in the ventral-lateral aspect of lumbosacral spinal cord in MOG-EAE. When YFP fluorescence was used in conjunction with a monoclonal antibody that recognizes CD11b; a marker of subsets of inflammatory cells, we were able to discern evidence of an early inflammatory attack on white matter axons. Finally, we show the accumulation of hyperphosphorylated neurofilament-H (hyperP-NF-H) expression in YFP+, lesioned WM areas and in a subpopulation of neuronal perikarya in the lumbar spinal cords of EAE mice.

Assessing the role of immuno-proteasomes in a mouse model of familial ALS

The accumulation of protein aggregates is thought to be an important component in the pathogenesis of mutant SOD1-induced disease. Mutant SOD1 aggregates appear to be cleared by proteasomes, at least in vitro, suggesting a potentially important role for proteasome degradation pathways in vivo. G93A SOD1 transgenic mice show an increase in proteasome activity and induction of immuno-proteasome subunits within spinal cord as they develop neurological symptoms. To determine what role immuno-proteasomes may have in mutant SOD1-induced disease, we crossed G93A SOD1 transgenic mice with LMP2-/- mice to obtain G93A SOD1 mice lacking the LMP2 immuno-proteasome subunit. G93A SOD1/LMP2-/- mice show significant reductions in proteasome function within spinal cord compared to G93A SOD1 mice. However, G93A SOD1/LMP2-/- mice show no change in motor function decline, or survival compared to G93A SOD1 mice. These results indicate that the loss of immuno-proteasome function in vivo does not significantly alter mutant SOD1-induced disease.

IL-15 and IL-15R alpha gene deletion: effects on T lymphocyte trafficking and the microglial and neuronal responses to facial nerve axotomy

IL-15 is a potent T cell chemoattractant, and this cytokine and its unique alpha subunits, IL-15R alpha, can modify immune cell expression of several T cell chemokines and their receptors. Facial nerve axotomy in mice leads to T cell migration across an intact blood-brain-barrier (BBB), and under certain conditions T cells can provide neuroprotection to injured neurons in the facial motor nucleus (FMN). Although chemokines and chemoattractant cytokines are thought to be responsible for T cell migration to the injured cell bodies, data addressing this question are lacking. This study tested the hypothesis that T cell homing to the axotomized FMN would be impaired in knockout (KO) mice with the IL-15 and IL-15R alpha genes deleted, and sought to determine if microglial responsiveness and motoneuron death are affected. Both IL-15KO and IL-15R alpha KO mice exhibited a marked reduction in CD3(+) T cells and had fewer MHC2(+) activated microglia in the injured FMN than their respective WT controls at day 14 post-axotomy. Although there was a relative absence of T cell recruitment into the axotomized FMN in both knockout strains, IL-15R alpha KO mice had five times more motoneuron death (characterized by perineuronal microglial clusters engulfing dead motoneurons) than their WT controls, whereas dead neurons in IL-15KO did not differ from their WT controls. Further studies are needed to dissect the mechanisms that underlie these observations (e.g., central vs. peripheral immune contributions).

Correction of humoral derangements from mutant superoxide dismutase 1 spinal cord

OBJECTIVE

We sought to define molecular and cellular participants that mediate motor neuron injury in amyotrophic lateral sclerosis using a coculture system.

METHODS

We cocultured embryonic stem cell-derived motor neurons with organotypic slice cultures from wild-type or SOD1G93A (MT) mice. We examined axon lengths and cell survival of embryonic stem cell-derived motor neurons. We defined and quantified the humoral factors that differed between wild-type and MT organotypic cultures, and then corrected these differences in cell culture.

RESULTS

MT spinal cord organotypic slices were selectively toxic to motor neurons as defined by axonal lengths and cell survival. MT spinal cord organotypic slices secreted higher levels of nitric oxide, interleukin (IL)-1beta, IL-6, and IL-12p70 and lower levels of vascular endothelial growth factor. The toxicity of MT spinal cord organotypic cultures was reduced and axonal lengths were restored to near normal by coculturing in the presence of reactive oxygen species scavenger, vascular endothelial growth factor, and neutralizing antibodies to IL-1beta, IL-6, and IL-12.

INTERPRETATION

MT spinal cord organotypic cultures overexpress certain factors and underexpress others, creating a nonpermissive environment for cocultured motor neurons. Correction of these abnormalities as a group, but not individually, restores axonal length to near normal. Such a "cocktail" approach to the treatment of amyotrophic lateral sclerosis should be investigated further.

Glia cells in amyotrophic lateral sclerosis: New clues to understanding an old disease?

In classic neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), the pathogenic concept of a cell-autonomous disease of motor neurons has been challenged increasingly in recent years. Macro- and microglial cells have come to the forefront for their role in multistep degenerative processes in ALS and respective disease models. The activation of astroglial and microglial cells occurs early in the pathogenesis of the disease and seems to greatly influence disease onset and promotion. The role of oligodendrocytes and Schwann cells remains elusive. In this review we highlight the impact of nonneuronal cells in ALS pathology. We discuss diverse glial membrane proteins that are necessary to control neuronal activity and neuronal cell survival, and summarize the contribution of these proteins to motor neuron death in ALS. We also describe recently discovered glial mechanisms that promote motor neuron degeneration using state-of-the-art genetic mouse technology. Finally, we provide an outlook on the extent to which these new pathomechanistic insights may offer novel therapeutic approaches.

Hyperimmune goat serum for amyotrophic lateral sclerosis

The authors report a patient with amyotrophic lateral sclerosis (ALS) who showed a lessening of deterioration in respiratory muscle strength during treatment with hyperimmune goat serum (HGS) (Aimspro). Respiratory function tests (RFTs) were measured by established protocols, and all measurements were expressed as a percentage of normal predicted values. The rate of decline was calculated by linear regression analysis. Respiratory muscle strength decline was less during 13 months of treatment with HGS (mean 1.3% per month, range 0.8-1.7%) compared to the preceding 13 months (mean 2.3% per month, range 1.2-3.1%), while a greater decline would be expected with disease progression. Comparison with similarly affected patients in the literature suggest that a decline of 4-5% per month of predicted values may be expected during the treatment phase.

Innate immunity in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition in which motor neurons are selectively targeted. Although the underlying cause remains unclear, evidence suggests a role for innate immunity in disease pathogenesis. Neuroinflammation in areas of motor neuron loss is evident in presymptomatic mouse models of ALS and in human patients. Efforts aimed at attenuating the inflammatory response in ALS animal models have delayed symptom onset and extended survival. Seemingly conversely, attempts to sensitize cells of the innate immune system and modulate their phenotype have also shown efficacy. Effectors of innate immunity in the CNS appear to have ambivalent potential to promote either repair or injury. Because ALS is a syndromic disease in which glutamate excitotoxicity, altered cytoskeletal protein metabolism, oxidative injury, mitochondrial dysfunction and neuroinflammation all contribute to motor neuron degeneration, targeting inflammation via modulation of microglial function therefore holds significant potential as one aspect of therapeutic intervention and could provide insight into the exclusive vulnerability of motor neurons.

Protective effects of an anti-inflammatory cytokine, interleukin-4, on motoneuron toxicity induced by activated microglia

Microglia-mediated cytotoxicity has been implicated in models of neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease, but few studies have documented how neuroprotective signals might mitigate such cytotoxicity. To explore the neuroprotective mechanism of anti-inflammatory cytokines, we applied interleukin-4 (IL-4) to primary microglial cultures activated by lipopolysaccharide as well as to activated microglia cocultured with primary motoneurons. lipopolysaccharide increased nitric oxide and superoxide (O(2) (.-)) and decreased insulin-like growth factor-1 (IGF-1) release from microglial cultures, and induced motoneuron injury in microglia-motoneuron cocultures. However, lipopolysaccharide had minimal effects on isolated motoneuron cultures. IL-4 interaction with microglial IL-4 receptors suppressed and nitric oxide release, and lessened lipopolysaccharide-induced microglia-mediated motoneuron injury. The extent of nitric oxide suppression correlated directly with the extent of motoneuron survival. Although IL-4 enhanced release of free IGF-1 from microglia in the absence of lipopolysaccharide, it did not enhance free IGF-1 release in the presence of lipopolysaccharide. These data suggest that IL-4 may provide a significant immunomodulatory signal which can protect against microglia-mediated neurotoxicity by suppressing the production and release of free radicals.

CD4(+) T cell-mediated facial motoneuron survival after injury: Distribution pattern of cell death and rescue throughout the extent of the facial motor nucleus

We have previously demonstrated that CD4(+) T cells transiently rescue facial motoneurons (FMN) from axotomy-induced death in immunodeficient mice. Three subpopulations of motoneurons have been observed within the facial motor nucleus following axotomy: one that always survives axotomy (50%), one that is amenable to rescue from axotomy-induced death through the addition of neurotrophic factors or CD4(+) T cells (30-40%), and one that always dies after axotomy (10-15%). The objective of this study was to anatomically map the extent of axotomy-induced cell death and immune cell rescue in the facial nucleus to study the differential survival capabilities of each subpopulation. Wild-type (WT) mice, recombinase activating gene 2 knockout (RAG-2 KO) mice, and RAG-2 KO mice reconstituted with CD4(+) T cells were subjected to right facial nerve axotomy. At 4 weeks post-axotomy, topographical mapping of axotomy-induced cell death throughout the rostro-caudal extent of the facial nucleus was accomplished in accordance with previously published maps of the subnuclear arrangement of the facial neurons. The results indicate that all 3 subpopulations of FMN can be found in each of the subnuclear groups throughout the entire rostro-caudal extent of the facial nucleus. These data are discussed in context of recent work in amyotrophic lateral sclerosis, a fatal motoneuron disease.

Intrathecal upregulation of granulocyte colony stimulating factor and its neuroprotective actions on motor neurons in amyotrophic lateral sclerosis

To investigate cytokine/chemokine changes in amyotrophic lateral sclerosis (ALS), we simultaneously measured 16 cytokine/chemokines (interleukin [IL]-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 [p70], IL-13, IL-17, interferon-gamma, tumor necrosis factor-alpha, granulocyte colony stimulating factor [G-CSF], macrophage chemoattractant protein-1 [MCP-1], and macrophage inflammatory protein-1beta) in cerebrospinal fluid (CSF) and sera from 37 patients with sporadic ALS and 33 controls using a multiplexed fluorescent bead-based immunoassay. We also conducted immunohistochemical analyses from 8 autopsied ALS cases and 6 nonneurologic disease controls as well as cell culture analyses of relevant cytokines and their receptors. We found that concentrations of G-CSF and MCP-1 were significantly increased in ALS CSF compared with controls. In spinal cords, G-CSF was expressed in reactive astrocytes in ALS cases but not controls, whereas G-CSF receptor expression was significantly decreased in motor neurons of spinal cords from ALS cases. Biologically, G-CSF had a protective effect on the NSC34 cell line under conditions of both oxidative and nutritional stress. We suggested that G-CSF has potentially neuroprotective effects on motor neurons in ALS and that downregulation of its receptor might contribute to ALS pathogenesis. On the other hand, MCP-1 correlated with disease severity, which may aggravate motor neuron damage.

Immune-mediated neuroprotection of axotomized mouse facial motoneurons is dependent on the IL-4/STAT6 signaling pathway in CD4+ T cells

The CD4(+) T lymphocyte has recently been found to promote facial motoneuron (FMN) survival after nerve injury. Signal Transducer and Activator of Transcription (STAT)4 and STAT6 are key proteins involved in the CD4(+) T cell differentiation pathways leading to T helper type (Th)1 and Th2 cell development, respectively. To determine which CD4(+) T cell subset mediates FMN survival, the facial nerve axotomy paradigm was applied to STAT4-deficient (-/-) and STAT6-/- mice. A significant decrease in FMN survival 4 weeks after axotomy was observed in STAT6-/- mice compared to wild-type (WT) or STAT4-/- mice. Reconstituting STAT6-/- mice with CD4(+) T cells obtained from WT mice promoted WT levels of FMN survival after injury. Furthermore, rescue of FMN from axotomy-induced cell death in recombination activating gene (RAG)-2-/- mice (lacking T and B cells) could be achieved only by reconstitution with CD4(+) T cells expressing functional STAT6 protein. To determine if either the Th1 cytokine, interferon-gamma (IFN-gamma) or the Th2 cytokine IL-4 is involved in mediating FMN survival, facial nerve axotomy was applied to IFN-gamma-/- and IL-4-/- mice. A significant decrease in FMN survival after axotomy occurred in IL-4-/- but not in IFN-gamma-/- mice compared to WT mice, indicating that IL-4 but not IFN-gamma is important for FMN survival after nerve injury. In WT mice, intracellular IFN-gamma vs. IL-4 expression was examined in CD4(+) T cells from draining cervical lymph nodes 14 days after axotomy, and substantial increase in the production of both CD4(+) effector T cell subsets was found. Collectively, these data suggest that STAT6-mediated CD4(+) T cell differentiation into the Th2 subset is necessary for FMN survival. A hypothesis relevant to motoneuron disease progression is presented.

Myostatin inhibition slows muscle atrophy in rodent models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease leading to motor neuron cell death, but recent studies suggest that non-neuronal cells may contribute to the pathological mechanisms involved. Myostatin is a negative regulator of muscle growth whose function can be inhibited using neutralizing antibodies. In this study, we used transgenic mouse and rat models of ALS to test whether treatment with anti-myostatin antibody slows muscle atrophy, motor neuron loss, or disease onset and progression. Significant increases in muscle mass and strength were observed in myostatin-antibody-treated SOD1(G93A) mice and rats prior to disease onset and during early-stage disease. By late stage disease, only diaphragm muscle remained significantly different in treated animals in comparison to untreated controls. Myostatin inhibition did not delay disease onset nor extend survival in either the SOD1(G93A) mouse or rat. Together, these results indicate that inhibition of myostatin does not protect against the onset and progression of motor neuron degenerative disease. However, the preservation of skeletal muscle during early-stage disease and improved diaphragm morphology and function maintained through late stage disease suggest that anti-myostatin therapy may promote some improved muscle function in ALS.

Anti-tissue transglutaminase IgA antibodies in peripheral neuropathy and motor neuronopathy

OBJECTIVES

The aim of the study was to investigate the occurence of anti-tissue transglutaminase antibodies (tTGA) in peripheral nerve disorders, and to correlate them with neurophysiologic findings and anti-glycolipid antibodies.

MATERIALS AND METHODS

We examined tTGA immunoglobulin-A serum level from 220 patients with polyneuropathy (acute inflammatory: n=90; chronic inflammatory: n=56; non-inflammatory: n=74) and 110 with motor neuron disease (MND).

RESULTS

Seven of the 330 neurologic patients (2.1%, six with polyneuropathy and one with MND) were positive for tTGA. Sixty-one of the 330 neurologic patients (18.4%) had slightly increased tTGA values compared with healthy controls. Increased tTGA values were associated with greater impairment of neurophysiologic findings, but not with the presence of anti-glycolipid antibodies.

CONCLUSIONS

We found a high prevalence of tTGA reactivity in patients with peripheral nerve disorders or MND. However, we were unable to demonstrate an increased risk of celiac disease in these diseases.

Immunization does not interfere with uptake and transport by motor neurons of the binding fragment of tetanus toxin

The nontoxic binding domain of tetanus toxin (fragment C or TTC) readily undergoes retrograde axonal transport from an intramuscular injection site. This property has led to investigation of TTC as a possible vector for delivering therapeutic proteins to motor neurons. However, the vast majority of individuals in the developed world have been vaccinated with tetanus toxoid and have circulating antitetanus antibodies that cross-react with TTC and may block the delivery of a TTC-linked therapeutic protein. However, it is uncertain whether the immune response is capable of completely neutralizing an intramuscular depot of protein prior to its internalization by presynaptic nerve terminals, where it is inaccessible to antibody. We have evaluated uptake of rhodamine-labeled TTC following intramuscular injection in normal animals and animals vaccinated with tetanus toxoid prior to injection of fluorescently labeled TTC. All animals demonstrated uptake of TTC, with fluorescence appropriately localized to the hypoglossal nerve and nucleus. The distribution and intensity of fluorescence within neurons and processes were indistinguishable between the two groups and were characteristic of TTC. Vaccinated animals showed levels of uptake of TTC into the brain comparable to those of immunologically naïve animals as measured by quantitative fluorimetry. All vaccinated animals had protective levels of antitetanus antibodies as measured by ELISA. Uptake of TTC by nerve terminals from an intramuscular depot is an avid and rapid process and is not blocked by vaccination associated with protection from tetanus toxin.

Anti-disialosyl antibodies mediate selective neuronal or Schwann cell injury at mouse neuromuscular junctions

The human paralytic neuropathy, Miller Fisher syndrome (MFS) is associated with autoantibodies specific for disialosyl epitopes on gangliosides GQ1b, GT1a, and GD3. Since these gangliosides are enriched in synaptic membranes, anti-ganglioside antibodies may target neuromuscular junctions (NMJs), thereby contributing to disease symptoms. We have shown previously that at murine NMJs, anti-disialosyl antibodies induce an alpha-latrotoxin-like effect, electrophysiologically characterized by transient massive increase of spontaneous neurotransmitter release followed by block of evoked release, resulting in paralysis of the muscle preparation. Morphologically, motor nerve terminal damage, as well as perisynaptic Schwann cell (pSC) death is observed. The relative contributions of neuronal and pSC injury to the paralytic effect and subsequent repair are unknown. In this study, we have examined the ability of subsets of anti-disialosyl antibodies to discriminate between the neuronal and glial elements of the NMJ and thereby induce either neuronal injury or pSC death. Most antibodies reactive with GD3 induced pSC death, whereas antibody reactivity with GT1a correlated with the extent of nerve terminal injury. Motor nerve terminal injury resulted in massive uncontrolled exocytosis with paralysis. However, pSC ablation induced no acute (within 1 h) electrophysiological or morphological changes to the underlying nerve terminal. These data suggest that at mammalian NMJs, acute pSC injury or ablation has no major deleterious influence on synapse function. Our studies provide evidence for highly selective targeting of mammalian NMJ membranes, based on ganglioside composition, that can be exploited for examining axonal-glial interactions both in disease states and in normal NMJ homeostasis.

ALS-IgG-induced selective motor neurone apoptosis in rat mixed primary spinal cord cultures

There is evidence that in sporadic amyotrophic lateral sclerosis (ALS) immunological mechanisms may be involved in the pathophysiology of the disease. We tested whether purified IgG from ALS patients induce cell death in rat mixed primary spinal cord cultures and compared this with the effect of IgG purified from patients with Guillain-Barré syndrome (GBS) or from healthy donors. Treatment with ALS-IgG increases caspase-3 apoptosis when compared with control IgG or with GBS-IgG, but does not induce death by necrosis. Because ALS is characterized by the selective loss of motor neurones, we next assessed the differential effect of ALS-IgG on motor neurones or astrocytes. We showed, semiquantitatively, that motor neurones are more susceptible to apoptosis when cultures were treated with ALS-IgG compared with control-IgG. In conclusion, we have demonstrated in primary spinal cord cultures that IgG from patients with ALS induces apoptosis selectively in motor neurones, and that the caspase-3 pathway is involved. This suggests that immunological mechanisms may contribute to the selective loss of motor neurones in ALS.

Subcellular localization of IgG from the sera of ALS patients in the nervous system

Immunoglobulin G (IgG) samples isolated from the sera of amyotrophic lateral sclerosis (ALS) and control patients were injected intraperitoneally into mice. After 24 h the mice were processed for immune electron microscopic immunohistochemistry to localize IgG in their nervous system. The injected ALS IgG was observed in the axon terminals of the lower motor neurons (MNs), localized to the microtubules and enriched in the rough endoplasmic reticulum (RER). In post-mortem spinal cord samples from ALS patients, IgG was similarly detected in the vicinity of the microtubules and in the RER of the MNs. IgG was neither found in the corresponding structures of MNs of mice injected with the control human IgG nor in post-mortem human control spinal cord samples. The data suggest that multiple antibodies directing to different structures of the MNs may play a role in their degeneration in ALS.

Multifocal motor neuropathy: current concepts and controversies

Multifocal motor neuropathy (MMN) is now a well-defined purely motor multineuropathy characterized by the presence of multifocal partial motor conduction blocks (CB), frequent association with anti-GM1 IgM antibodies, and usually a good response to high-dose intravenous immunoglobulin (IVIg) therapy. However, several issues remain to be clarified in the diagnosis, pathogenesis, and therapy of this condition including its nosological position and its relation to other chronic dysimmune neuropathies; the degree of CB necessary for the diagnosis of MMN; the existence of an axonal form of MMN; the pathophysiological basis of CB; the pathogenetic role of antiganglioside antibodies; the mechanism of action of IVIg treatments in MMN and the most effective regimen; and the treatment to be used in unresponsive patients. These issues are addressed in this review of the main clinical, electrophysiological, immunological, and therapeutic features of this neuropathy.

Neuroinflammation in the pathogenesis of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a devastating motor neuron disorder. Traditionally regarded as a 'neuron only' disease, recent evidence suggested that other cells contribute critically to the pathogenesis. This review provides a short synopsis of the role neuroinflammation and microglial cells play in the disease and its animal models. A better understanding of neuroinflammation in motor neuron degeneration and amyotrophic lateral sclerosis disease progression promises to improve the rational design of greatly needed therapies.

Clinical and electrophysiologic correlates of IVIg responsiveness in CIDP

To identify clinical and electrophysiologic features related to IV immunoglobulin (IVIg) responsiveness in chronic inflammatory demyelinating polyneuropathy (CIDP), the authors conducted a multicenter study on 312 patients with CIDP (199 responders and 113 nonresponders). Muscle atrophy and decreased compound muscle action potential were pronounced in nonresponders of IVIg. Male gender, longer disease duration, and slow progression of symptoms were also associated with IVIg unresponsiveness. Features suggesting axonal dysfunction in peripheral nerves indicated IVIg unresponsiveness in CIDP.

Aging in polio

For a disease that was "conquered" some 40 years ago with the onset of effective vaccination, the issues of long-term survivors of paralytic polio as they age continue to present challenges to rehabilitation specialists. Aging with polio is a definition of PPS. There are over a million patients with PPS in the United States. Management has to include the appropriate use of exercises, appropriate bracing and support, and, in the case of bulbar and respiratory symptoms, the appropriate use of speech therapy services and ventilatory support. There are no prospective randomized trials studying the treatment of weakness and fatigue in PPS. Pharmacologic interventions are limited at this time but include anticholinergics for muscle weakness and dopaminergic agents or amantadine to control central fatigue. The pathophysiology of aging with polio is consistent with neuronal loss and denervation lying at the heart of the developing disorder, whereas the central nervous system components of the fatigue syndrome may be related to central changes with neuronal loss in the basal ganglia and reticular-activating system. Many of the survivors of the polio epidemics are in their later retirement years, and their needs will increase as they have other disabilities due to natural aging. Sensitivity to some of the special issues in PPS may help to avoid complications. Polio is an active infection in the third world. Although great strides have been made, the disease is endemic in eight nations and is threatening to spread. The lessons learned in treating PPS now will be useful in years to come as these individuals age and manifest PPS in the future.

Overexpression of GD1a ganglioside sensitizes motor nerve terminals to anti-GD1a antibody-mediated injury in a model of acute motor axonal neuropathy

Anti-GD1a ganglioside antibodies (Abs) are the serological hallmark of the acute motor axonal form of the post-infectious paralysis, Guillain-Barre syndrome. Development of a disease model in mice has been impeded by the weak immunogenicity of gangliosides and the apparent resistance of GD1a-containing neural membranes to anti-GD1a antibody-mediated injury. Here we used mice with altered ganglioside biosynthesis to generate such a model at motor nerve terminals. First, we bypassed immunological tolerance by immunizing GD1a-deficient, beta-1,4-N-acetylgalactosaminyl transferase knock-out mice with GD1a ganglioside-mimicking antigens from Campylobacter jejuni and generated high-titer anti-GD1a antisera and complement fixing monoclonal Abs (mAbs). Next, we exposed ex vivo nerve-muscle preparations from GD1a-overexpressing, GD3 synthase knock-out mice to the anti-GD1a mAbs in the presence of a source of complement and investigated morphological and electrophysiological damage. Dense antibody and complement deposits were observed only over presynaptic motor axons, accompanied by severe ultrastructural damage and electrophysiological blockade of motor nerve terminal function. Perisynaptic Schwann cells and postsynaptic membranes were unaffected. In contrast, normal mice were not only unresponsive to immunization with GD1a but also resistant to neural injury during anti-GD1a Ab exposure, demonstrating the central role of membrane antigen density in modulating both immune tolerance to GD1a and axonal susceptibility to anti-GD1a Abmediated injury. Identical paralyzing effects were observed when testing mouse and human anti-GD1a-positive sera. These data indicate that anti-GD1a Abs arise via molecular mimicry and are likely to be clinically relevant in injuring peripheral nerve axonal membranes containing sufficiently high levels of GD1a.

Role of the immune system in the maintenance of mouse facial motoneuron viability after nerve injury

In the field of neuroimmunology, an emerging area of research involves the role that the immune system plays in neural injury and repair. Such immune:neural interactions may involve both neuroprotective and neurodestruction actions. To begin to address the compelling, and clinically relevant, issue of how the immune system impacts neural reparative processes, we combined the well described facial nerve injury paradigm, a simple neural injury model, with various immunodeficient mouse models, in order to delineate the contributing immune cells/factors involved in neural injury and repair. We have discovered a role for the CD4+ T cell in mediating facial motoneuron survival after facial nerve injury in the mouse. In this review, we present an overview of our work to date in this field and discuss future directions relevant to understanding key elements in the crosstalk between the immune:neural systems that develops subsequent to injury and/or trauma.

Paraneoplastic encephalomyelitis/sensory motor peripheral neuropathy - an autopsy case study

Paraneoplastic neurological anti-Hu syndrome is one of the most frequent remote effects of cancer and usually manifests as encephalomyelitis combined with peripheral neuropathy. Subacute sensory neuronopathy, which results from the inflammatory destruction of sensory neurone cell bodies in the dorsal root ganglia, is thought to be the principal presentation of peripheral neuropathy. In addition to sensory involvement, evidence of motor nerve involvement is frequently found. The mechanisms of motor involvement remain largely unclear and there have been only a limited number of pathological studies. We present an autopsy case study of anti-Hu paraneoplastic encephalomyelitis/sensory-motor neuropathy, which confirms an inflammatory paraneoplastic destruction of sensory neuron cell bodies in the dorsal root ganglia and lower motor neurons in the spinal cord, as a cause of clinically rapidly progressive peripheral sensory-motor neuropathy.

CD4-positive T cell-mediated neuroprotection requires dual compartment antigen presentation

Our laboratory discovered that CD4-positive (CD4+) T cells of the immune system convey transitory neuroprotection to injured mouse facial motoneurons (FMNs) (Serpe et al., 1999, 2000, 2003). A fundamental question in the mechanisms responsible for neuroprotection concerns the identity of the cell(s) that serves as the antigen-presenting cell (APC) to activate the CD4+ T cells. Here, we first establish that CD4+ T cells reactive to non-CNS antigen fail to support FMN survival and, second, demonstrate a two-compartment model of CD4+ T cell activation. Mouse bone marrow (BM) chimeras were developed that discriminate between resident antigen-presenting host cell and BM-derived antigen-presenting donor cell expression of major histocompatibility complex II within central and peripheral compartments, respectively. After facial nerve transection, neither compartment alone is sufficient to result in activated CD4+ T cell-mediated FMN survival. Rather, CD4+ T cell-mediated neuroprotection appears to depend on both resident microglial cells in the central compartment and a BM-derived APC in the peripheral compartment. This is the first in vivo report demonstrating a neuroprotective mechanism requiring APC functions by resident (i.e., parenchymal) microglial cells.

Various immunization protocols for an acute motor axonal neuropathy rabbit model compared

Various ganglioside immunization protocols were examined to refine the procedure for establishing an animal model of acute motor axonal neuropathy. The most effective was subcutaneous injection of an emulsion of 2.5mg of bovine brain ganglioside mixtures, keyhole lympet hemocyanin, and complete Freund's adjuvant to Japanese white rabbits, repeated at 3-week intervals. Under that protocol, all the rabbits developed marked flaccid paralysis associated with plasma anti-GM1 IgG antibody. This acute motor axonal neuropathy rabbit model also could be reproduced by the use of incomplete Freund's adjuvant, methylated bovine serum albumin, and New Zealand white rabbits. These results provide useful information for the confirmation of and further research on the model.