The Cytotoxicity of Epsilon Toxin from Clostridium perfringens on Lymphocytes Is Mediated by MAL Protein Expression.

Epsilon toxin (Etx) from Clostridium perfringens is a pore-forming protein that crosses the blood-brain barrier, binds to myelin, and, hence, has been suggested to be a putative agent for the onset of multiple sclerosis, a demyelinating neuroinflammatory disease. Recently, myelin and lymphocyte (MAL) protein has been identified to be a key protein in the cytotoxic effect of Etx; however, the association of Etx with the immune system remains a central question. Here, we show that Etx selectively recognizes and kills only human cell lines expressing MAL protein through a direct Etx-MAL protein interaction. Experiments on lymphocytic cell lines revealed that MAL protein-expressing T cells, but not B cells, are sensitive to Etx and reveal that the toxin may be used as a molecular tool to distinguish subpopulations of lymphocytes. The overall results open the door to investigation of the role of Etx and Clostridium perfringens on inflammatory and autoimmune diseases like multiple sclerosis.

Acute Effect of Pore-Forming Clostridium perfringens ε-Toxin on Compound Action Potentials of Optic Nerve of Mouse.

ε-Toxin is a pore forming toxin produced by Clostridium perfringens types B and D. It is synthesized as a less active prototoxin form that becomes fully active upon proteolytic activation. The toxin produces highly lethal enterotoxaemia in ruminants, has the ability to cross the blood-brain barrier (BBB) and specifically binds to myelinated fibers. We discovered that the toxin induced a release of ATP from isolated mice optic nerves, which are composed of myelinated fibers that are extended from the central nervous system. We also investigated the effect of the toxin on compound action potentials (CAPs) in isolated mice optic nerves. When nerves were stimulated at 100 Hz during 200 ms, the decrease of the amplitude and the area of the CAPs was attenuated in the presence of ε-toxin. The computational modelling of myelinated fibers of mouse optic nerve revealed that the experimental results can be mimicked by an increase of the conductance of myelin and agrees with the pore forming activity of the toxin which binds to myelin and could drill it by making pores. The intimate ultrastructure of myelin was not modified during the periods of time investigated. In summary, the acute action of the toxin produces a subtle functional impact on the propagation of the nerve action potential in myelinated fibers of the central nervous system with an eventual desynchronization of the information. These results may agree with the hypothesis that the toxin could be an environmental trigger of multiple sclerosis (MS).