Clostridium perfringens Epsilon Toxin Causes Selective Death of Mature Oligodendrocytes and Central Nervous System Demyelination

Abstract

Clostridium perfringens epsilon toxin (ε-toxin) is responsible for a devastating multifocal central nervous system (CNS) white matter disease in ruminant animals. The mechanism by which ε-toxin causes white matter damage is poorly understood. In this study, we sought to determine the molecular and cellular mechanisms by which ε-toxin causes pathological changes to white matter. In primary CNS cultures, ε-toxin binds to and kills oligodendrocytes but not astrocytes, microglia, or neurons. In cerebellar organotypic culture, ε-toxin induces demyelination, which occurs in a time- and dose-dependent manner, while preserving neurons, astrocytes, and microglia. ε-Toxin specificity for oligodendrocytes was confirmed using enriched glial culture. Sensitivity to ε-toxin is developmentally regulated, as only mature oligodendrocytes are susceptible to ε-toxin; oligodendrocyte progenitor cells are not. ε-Toxin sensitivity is also dependent on oligodendrocyte expression of the proteolipid myelin and lymphocyte protein (MAL), as MAL-deficient oligodendrocytes are insensitive to ε-toxin. In addition, ε-toxin binding to white matter follows the spatial and temporal pattern of MAL expression. A neutralizing antibody against ε-toxin inhibits oligodendrocyte death and demyelination. This study provides several novel insights into the action of ε-toxin in the CNS. (i) ε-Toxin causes selective oligodendrocyte death while preserving all other neural elements. (ii) ε-Toxin-mediated oligodendrocyte death is a cell autonomous effect. (iii) The effects of ε-toxin on the oligodendrocyte lineage are restricted to mature oligodendrocytes. (iv) Expression of the developmentally regulated proteolipid MAL is required for the cytotoxic effects. (v) The cytotoxic effects of ε-toxin can be abrogated by an ε-toxin neutralizing antibody.

Oligodendrocyte death results in immune-mediated CNS demyelination

“…In line with this idea, it has been shown recently that nascent MS lesions with oligodendrocyte loss, in the absence of the adaptive immune infiltrates, occurred in a patient who tested positive for the Clostridium perfringens type B, indicating that MS might be triggered by an agent cytotoxic to oligodendrocytes 33 . Both type B and D strains of C. perfringens cause a severe demyelinating disease in ruminant animals that is similar to human MS by producing ε-toxin, which specifically targets and kills mature oligodendrocytes in the CNS 34 .…”

F199E substitution reduced toxicity ofClostridium perfringensepsilon toxin by depriving the receptor binding capability

“…32 Moreover, demyelination occurs in very low ETX concentrations (< 0.01nM) 33 at which it has not been established that ETX can form heptamers. We also found that extracellular Ca 2C and intracellular Ca 2C stores were both involved in ETX induced increase in intracellular Ca 2C concentration.…”

Oral Multiple Sclerosis Drugs Inhibit the In vitro Growth of Epsilon Toxin Producing Gut Bacterium, Clostridium perfringens

“…We have previously proposed that a bacterial neurotoxin, epsilon toxin, from the anaerobic gut bacterium, Clostridium perfringens , may play a pivotal role in triggering newly forming MS lesions (Rumah et al, 2013, 2015; Linden et al, 2015). Epsilon toxin (ETX) is a rational candidate MS trigger due to its tropism for the blood-brain barrier (BBB) and for the myelin sheath; both of which are specifically damaged during each MS relapse (Dorca-Arévalo et al, 2008; Rumah et al, 2013; Linden et al, 2015).…”

“…Epsilon toxin (ETX) is a rational candidate MS trigger due to its tropism for the blood-brain barrier (BBB) and for the myelin sheath; both of which are specifically damaged during each MS relapse (Dorca-Arévalo et al, 2008; Rumah et al, 2013; Linden et al, 2015). Remarkably, newly forming MS lesions display evidence of BBB breakdown, oligodendrocyte cell death and early microglial activation in the absence of a peripheral inflammatory infiltrate (Barnett and Prineas, 2004).…”

“…Remarkably, newly forming MS lesions display evidence of BBB breakdown, oligodendrocyte cell death and early microglial activation in the absence of a peripheral inflammatory infiltrate (Barnett and Prineas, 2004). While the triggering agent of these early pathologic changes remains unknown, C. perfringens epsilon toxin serves as a provocative candidate due to its tissue specificity and resultant mechanistic plausibility (Rumah et al, 2013, 2015; Linden et al, 2015). …”