Antibodies to calcium channels from ALS patients passively transferred to mice selectively increase intracellular calcium and induce ultrastructural changes in motoneurons

Abstract

Antibodies to Ca channels in ALS patients IgG can be demonstrated to enhance Ca current and cause cell injury and death in a motoneuron cell line in vitro. To determine whether these antibodies can alter neuronal calcium homeostasis in vivo IgG fractions from six ALS patients were injected intraperitoneally into mice, and neurons assayed by ultrastructural techniques for calcium content. After 24 h, all six ALS IgG by (40 mg/animal) increased vesicle number in spinal motoneuron axon terminals, and in boutons synapsing on spinal motoneurons. Using the oxalate-pyroantimonate technique for calcium precipitation, these antibodies produced dose-dependent calcium increases either in axon terminal synaptic vesicles and mitochondria, or in rough endoplasmic reticulum, mitochondria, and Golgi complex of spinal motoneuron and frontal cortex pyramidal cells. ALS IgG was itself internalized and also induced neurofilament H phosphorylation. The observed changes in ultrastructure and calcium compartmentation were restricted to motoneurons; normal and disease control IgG, which did not possess antibodies enhancing calcium entry, did not exert similar effects. These data demonstrate that ALS IgG containing Ca-channel antibodies can alter calcium homeostasis of motoneurons in vivo.

Calcium Signaling Pathways Mediating Synaptic Potentiation Triggered by Amyotrophic Lateral Sclerosis IgG in Motor Nerve Terminals

“…These results indicate that the ALS-IgG effect is not restricted to the NMJ and is not specific for a particular type of skeletal muscle NMJ. This hypothesis is supported by the specific alteration of motoneurons ([Ca 2ϩ ] i increment) after systemic injection of ALS-IgG (Engelhardt et al, 1995;Pullen and Humphreys, 2000;Pullen et al, 2004) but no [Ca 2ϩ ] i increment in synaptosomes from cortex (Thomas and Dunn, 1997). This indicates that ALSIgG somehow exhibits specificity to affect motoneurons.…”

“…Interestingly, ALS-IgG enhanced asynchronous release, which is reduced by mitochondrial Ca 2ϩ uptake (David and Barrett, 2003). Thus, the ALS-IgG-sp is likely to affect both ER and mitochondrial homeostatic Ca 2ϩ control (Engelhardt et al, 1995), which may lead to caspase activation (i.e., caspase-3 activation through ER, caspase-12 or mitochondrial, caspase-9) (Orrenius et al, 2003;Demestre et al, 2005). In agreement with these assumptions, apoptosis mediated by mitochondrial dysfunction has been reported in ALS patients (Strong, 2003).…”

“…Interestingly, some of this evidence correlates with observations made in research animals. In rodents treated with IgG from ALS patients (ALS-IgG), a [Ca 2ϩ ] i increment associated with degenerative structural alterations in motoneurons and synaptic plasticity at neuromuscular transmission was also observed (Engelhardt et al, 1995;Fratantoni et al, 2000;Pullen and Humphreys, 2000;Pullen et al, 2004). ALS-IgG from ϳ50% of ALS patients trigger synaptic potentiation in spontaneous neuromuscular transmission, together with [Ca 2ϩ ] i increment (ex vivo), and can induce long-term neuromuscular dysfunction in vivo (Uchitel et al, 1988(Uchitel et al, , 1992Engelhardt et al, 1995;O'Shaughnessy et al, 1998;Mohamed et al, 2002).…”

“…S1, available at www.jneurosci.org as supplemental material). This pathway may account for [Ca 2ϩ ] i increment in motoneurons after a systemic injection of ALS-IgG (Engelhardt et al, 1995;Pullen and Humphreys, 2000;Pullen et al, 2004 Fig. S1, available at www.…”

Differential Localization of Voltage-Dependent Calcium Channel α1Subunits at the Human and Rat Neuromuscular Junction

“…First, ALS IgG has been shown to increase calcium flux through P-type channels (Llinás et al, 1993) and to stimulate the spontaneous release of acetylcholine at the mouse NMJ . Second, mice injected with AL S IgG exhibited an increase in synaptic vesicle number and intracellular calcium levels in MN terminals (Engelhardt et al, 1995). Finally, application of ALS IgG to a differentiated hybrid M N cell line caused an increase in calcium flux (Mosier et al, 1995) and was cytotoxic to these cells .…”