Cytotoxic CD8⁺T Cell–Neuron Interactions: Perforin-Dependent Electrical Silencing Precedes But Is Not Causally Linked to Neuronal Cell Death

Abstract

Cytotoxic CD8ϩ T cells are considered important effector cells contributing to neuronal damage in inflammatory and degenerative CNS disorders. Using time-lapse video microscopy and two-photon imaging in combination with whole-cell patch-clamp recordings, we here show that major histocompatibility class I (MHC I)-restricted neuronal antigen presentation and T cell receptor specificity determine CD8 ϩ T-cell locomotion and neuronal damage in culture and hippocampal brain slices. Two separate functional consequences result from a direct cell-cell contact between antigen-presenting neurons and antigen-specific CD8 ϩ T cells. (1) An immediate impairment of electrical signaling in single neurons and neuronal networks occurs as a result of massive shunting of the membrane capacitance after insertion of channel-forming perforin (and probably activation of other transmembrane conductances), which is paralleled by an increase of intracellular Ca 2ϩ levels (within Ͻ10 min). (2) Antigen-dependent neuronal apoptosis may occur independently of perforin and members of the granzyme B cluster (within ϳ1 h), suggesting that extracellular effects can substitute for intracellular delivery of granzymes by perforin. Thus, electrical silencing is an immediate consequence of MHC I-restricted interaction of CD8 ϩ T cells with neurons. This mechanism is clearly perforin-dependent and precedes, but is not causally linked, to neuronal cell death.

Exploring the origins of grey matter damage in multiple sclerosis

“…These include antigen-specific and antigen-independent mechanisms as well as cell contact-dependent and -independent processes 85 . However, all of the major cytotoxic mechanisms that have been proposed -including the release of perforin 86 or granzymes 87 , involvement of Fas/Fas-ligand 88 , cell lysis by TNF receptor-related apoptosisinducing ligand (TRAIL) 89 and the induction by IFN-g of neuron-specific, calcium-permeable complexes between IFN-g-receptor and the glutamate receptor GluR1 90 -have been described mainly in experimental models. It is important to note that the ability to kill target cells by perforinor Fas/Fas-ligand-mediated lysis, which is typically attributed only to CD8+ T cells, has also been shown for human CD4+ T cells 91 .…”

Glatiramer Acetate Attenuates Pro-Inflammatory T Cell Responses but Does Not Directly Protect Neurons from Inflammatory Cell Death

“…21,22 Neuronal cultures were incubated at 37.0°C and 5% CO 2 and held in culture for up to 5 to 7 days before experiments. Immunocytochemical staining (see below) for nuclei (4,6-diamidino-2-phenylindole [DAPI]), neurons (Microtubule associated protein 2a; MAP2a), and astrocytes (glial fibrillary acidic protein) provided a purity of ϳ80% of our neuronal cell culture system.…”

“…22 For a subset of experiments, GA (100 g/ml) and mannitol (200 mg/ml) were added to the extracellular solution before adjustment of pH and osmolality. All neurons included in the analysis had a resting membrane potential negative to Ϫ50 mV, the access resistance was typically in the range of 5 to 15 M⍀ and series resistance compensation of more than 40% was routinely used.…”

“…To analyze the impact of GA on the activity of neuronal networks, different parameters of neuronal network activity were determined using the multi-electrode array technique 22,23 in the absence and the presence of GA at a concentration of 10 g/ml. Multi-electrode array detects compound field potentials in the spatial vicinity of multiple extracellular electrodes in densely cultured hippocampal neurons, which are capable of generating spontaneous synchronized activity.…”

Genistein downregulates presenilin 1 and ubiquilin 1 expression

“…As for prion disease, the lympho-reticular system has been implicated as the route of transmission of pathogenic prion from the gut to the brain. Indeed, T cells are considered to be important effector cells contributing to neuronal damage in degenerative CNS disorders (15). This implies that some lymphocytes can interact with neuronal cells in the brain.…”