Izabella Obál

Recruitment of activated microglia cells in the spinal cord of mice by ALS IgG

Mice were injected i.p. with IgG samples of different patients to test whether IgG from amyotrophic lateral sclerosis (ALS) can initiate an immune/inflammatory reaction targeting motor neurons. All IgG samples of five ALS patients and none of the disease controls recruited activated microglia cells in the ventral horn of the spinal cord. CD3 lymphocytes were not accumulated in the same tissue. Similar reaction was evoked by injection of IgG from guinea pigs with experimental autoimmune gray matter disease (EAGMD) induced by immunization with the homogenate of the ventral horn of bovine spinal cord. The results indicate that ALS IgG and anti-motoneuron IgG induce microglia reaction targeting motor neurons without initiating T cell response in the recipient mice.

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.

Axotomy induces contrasting changes in calcium and calcium-binding proteins in oculomotor and hypoglossal nuclei of Balb/c mice.

Motor neurons with different susceptibility to degeneration have been identified in amyotrophic lateral sclerosis (ALS). Increase of intracellular calcium has been proposed as a mediator, amplifying the damage through a positive feedback of the known pathological processes. Accordingly, the potential of motor neurons to limit calcium increases during injury might be proportional to their viability. A basic mechanism of reducing calcium amplitudes depends on the calcium‐buffering capacity, determined by the calcium‐binding protein content. In this study, oculomotor and hypoglossal neurons, prototypes of resistant and vulnerable motor neurons in ALS were examined in axotomy experiments. Total calcium‐, parvalbumin‐, and calbindin‐D28k levels of motor neurons of adult mice were characterized by electron microscopic histochemistry and light microscopic immunostaining. In hypoglossal neurons, compared with oculomotor neurons, larger and more enduring increases of calcium were detected. The perikarya of hypoglossal neurons remained immunonegative for both parvalbumin and calbindin‐D28k. Qualitatively, no major cell loss was noted after axotomy, but a decreased neuronal marker staining at days 1–14 suggested a reversible injury of hypoglossal neurons. Oculomotor neurons were not stained for calbindin‐D28k but stained for parvalbumin in control conditions, staining which increased at postoperative days 7–14 before returning to baseline. Neuronal marker staining did not change in these cells during the observed period. The higher level of parvalbumin in resistant motor neurons and their ability to up‐regulate parvalbumin after injury, paralleled by a smaller increase of intracellular calcium suggest that parvalbumin may have a protective effect in these cells. J. Comp. Neurol. 499:17–32, 2006.

Altered calcium in motoneurons by IgG from human motoneuron diseases

Obal I, Siklós L, Engelhardt JI. Altered calcium in motoneurons by IgG from human motoneuron diseases.

Identification of a Novel GLA Gene Mutation, p.Ile239Met, in Fabry Disease With a Predominant Cardiac Phenotype

Fabry disease (FD) is an X-linked inherited lysosomal storage disorder caused by mutations in the GLA gene, encoding for the enzyme α-galactosidase A. Although hundreds of mutations in the GLA gene have been described, many of them are variants of unknown significance. Here we report a novel GLA mutation, p.Ile239Met, identified in a large Hungarian three-generation family with FD. A 69 year-old female index patient with a clinical history of renal failure, hypertrophic cardiomyopathy, and 2nd degree AV block was screened for mutation in the GLA gene. Genetic screening identified a previously unreported heterozygous mutation in exon 5 of the GLA gene (c.717A>G; p.Ile239Met). Family screening indicated that altogether 6 family members carried the mutation (5 females, 1 male, average age: 55 ± 16 years). Three family members, including the index patient, manifested the cardiac phenotype of hypertrophic cardiomyopathy, while two other family members were diagnosed with left ventricular hypertrophy. Taking affection status as the presence of hypertrophic cardiomyopathy, left ventricular hypertrophy or elevated lyso-Gb3 levels, all affected family members carried the mutation. Linkage analysis of the family gave a two-point LOD score of 2.01 between the affection status and the p.Ile239Met GLA mutation. Lyso-Gb3 levels were elevated in all carrier family members (range: 2.4-13.8 ng/mL; upper limit of normal +2STD: ≤ 1.8 ng/mL). The GLA enzyme level was markedly reduced in the affected male family member (< 0.2 µmol/L/hour; upper limit of normal ± 2STD: ≥ 2.6 µmol/L/hour). We conclude that the p. Ile239Met GLA mutation is a pathogenic mutation for FD associated with predominant cardiac phenotype.

Mental Disturbances in Parkinson's Disease and Related Disorders: The Role of Excitotoxins

The pathomechanism behind the neurodegenerative process in Parkinsons disease involves damage to the dopaminergic and nondopaminergic systems with dysfunctioning of the dopaminergic-glutamatergic circuitry in the basal ganglional neural processing. Excitotoxicity may contribute markedly to neuronal damage and loss. Beside the cardinal motor signs of the disease, non-motor symptoms, including mental disturbances, are characteristic features of the clinical course. Affective or autonomic changes may precede motor symptoms. Neuroprotective drugs are not yet available. However, new modes of therapy targeting the defective dopaminergic-glutamatergic system might also be effective both for symptomatologic treatment and for neuroprotection. Alterations in the kynurenine pathway have been demonstrated in Parkinsons disease. Preclinical studies suggest that intervention in the kynurenine pathway may result in neuroprotection and additionally alleviate the symptoms through influencing the glutamatergic neurotransmission.

Axotomy Leads to Reduced Calcium Increase and Earlier Termination of CCL2 Release in Spinal Motoneurons with Upregulated Parvalbumin Followed by Decreased Neighboring Microglial Activation

BACKGROUND Motoneurons with naturally elevated calcium binding protein content, such as parvalbumin, are more resistant against injury. Furthermore, increase of intracellular calcium, which plays a pivotal role in injury of neurons, could be moderated by elevating their calcium binding proteins. OBJECTIVE To test whether by elevating parvalbumin content of motoneurons, activation of neighboring microglial cells, a robust component of the inflammatory reaction after injury, could be influenced. METHODS Mice overexpressing neuronal parvalbumin were derived and the spinal motoneurons were challenged by cutting the sciatic nerve. At postoperative days 1, 4, 7, 14 and 21 the change of the chemokine ligand 2 immunostaining in the motoneurons and the activation of microglial cells, measured as alterations in CD11b immunostaining were determined. Calcium level of motoneurons was tested electron microscopically at postoperative day 7. RESULTS After axotomy, increased level of chemokine ligand 2 was detected in the lumbar motoneurons. The staining intensity reached its maximum at day 7 and decayed faster in transgenic mice compared to controls. Microglial activation around motoneurons attenuated faster in parvalbumin overexpressing mice, too, but the decrease of microglial activation was delayed compared to the decline of the chemokine ligand 2 signal. At the time when the microglial reaction peaked, no intracellular calcium increase was detected in the motoneurons of transgenic mice, in contrast to the twofold increase in wild type animals. CONCLUSION Increased calcium buffering capacity, which augments resistance of motoneurons against calcium-mediated injury, leads to earlier termination of motoneuronal emission of CCL2 followed by a reduction of neighboring microglial activation after axotomy.

Presymptomatically applied AMPA receptor antagonist prevents calcium increase in vulnerable type of motor axon terminals of mice modeling amyotrophic lateral sclerosis

Increased intracellular calcium (Ca), which might be the consequence of an excess influx through Ca-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, plays a crucial role in degeneration of motor neurons. Previously we demonstrated that the presymptomatic application of AMPA receptor antagonist, talampanel, could reduce Ca elevation in spinal motor neurons of mice carrying the G93A mutation of superoxide dismutase 1 (SOD1), modeling amyotrophic lateral sclerosis (ALS). It remained to be examined whether the remote, functionally semi-autonomous motor axon terminals could be rescued from the Ca overload, or if the terminals, where the degeneration possibly starts, already experience intractable changes at early time points. Thus using electron microscopic techniques, we measured the Ca level of motor axon terminals in the interosseus muscle of the SOD1 mutant animals, which are prototypes of vulnerable nerve endings in ALS. In line with the results obtained in the perikarya, talampanel treatment could reduce Ca increase evoked by the presence of mutant SOD1 in the axon terminals if the treatment was started presymptomatically but not at an early symptomatic stage. We also tested the Ca level in the cell bodies and axon terminals of the oculomotor neurons, which are resistant to the disease. Neither Ca increase, nor talampanel effect could be demonstrated at either time point. This is consistent with the observations that oculomotor neurons contain increased level of Ca buffer, which could reduce excess Ca load, and they also express glutamate receptor subunit type 2, which renders AMPA receptors impermeable to Ca.

Paraneoplastic neuromyelitis optica spectrum disorder: A case report and review of the literature

Neuromyelitis optica spectrum disorders (NMOSD) are demyelinating, autoimmune diseases affecting the central nervous system. Typically, recurrent optic neuritis and longitudinal extensive transverse myelitis dominates the clinical picture. In most cases NMOSD are associated with autoantibodies targeting the water channel aquaporin-4 (AQP-4). NMOSD usually present in young adults. Clinical findings suggestive of NMOSD in elderly patients should raise the suspicion of a paraneoplastic etiology. To our knowledge, we report the first case of a 66 year-old female patient with paraneoplastic NMOSD that is associated with squamous cell lung carcinoma. Anti-AQP-4 was present in both the serum and cerebrospinal fluid of the patient. However, immunhistological staining of the malignant tissue did not show presence of AQP-4 on the surface of tumour cells.

Calcium ion is a common denominator in the pathophysiological processes of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), the most frequent motor neuron disease is characterized by progressive muscle weakness caused by the degeneration of the motor neurons in the spinal cord and motor cortex. However, according to the recent observations, ALS is a rather complex syndrome which frequently involves symptoms of cognitive impairment. Therefore, ALS cases can be interpreted in a clinico-pathological spectrum spanning from the classical ALS involving only the motor system to the fronto-temporal dementia. The progression of the disease, however, manifested in the degeneration of the upper and lower motor neurons, is based on the same complex pathobiology. The main elements of the pathomechanism, such as oxidative stress, excitotoxicity, immune/inflammatory processes and mitochondrial dysfunction are well described already, which operate in orchestrated way and amplify the deleterious effect of each other. It is assumed that calcium ions act as a catalyst in this interaction, hence each of the individual mechanisms has strong, positive and reciprocal calcium dependence thus may combine the individual pathological processes into a unified escalating mechanism of neuronal destruction. This review provides an overview of the role of calcium in connecting and amplifying the major mechanisms which lead to degeneration of the motor neurons in ALS.