Differential pattern of neurotoxicity induced by the gliadin peptides p31-43 and p57-68 in in vitro model of epilepsy

Epilepsy is a central nervous system (CNS) disorder causing repeated seizures due to a transient excessive or synchronous alteration in the electrical activity of the brain. Several neurological disorders have been associated to gluten-related diseases (GRD), including epilepsy. However, the molecular mechanisms that associate GRD and epileptogenesis are still unknown. Our previous data have shown that the gliadin peptide 31-43 (p31-43) enhanced number and duration of seizures induced by kainate in mice and exacerbated CA3-kainate-induced neurotoxicity in organotypic hippocampal slices. Here, we investigated whether another important gliadin peptide p57-68 may exerts effects similar to p31-43 on kainate-induced neurotoxicity. We find that both peptides exacerbate kainate-induced damage in the CA3 region once simultaneously challenged. However, after pre-incubation, p31-43 additionally exacerbates neurotoxicity in the CA1 region, while p57-68 does not. These data suggested differential intracellular mechanisms activated by the peptides. Indeed, analysing intracellular signalling pathways we discover that p31-43 induces significant intracellular changes, including increased phosphorylation of Akt, Erk1/2, and p65, decreased p38 phosphorylation, and deacetylation of nuclear histone-3. Based on these observations, we demonstrate that p31-43 likely activates specific intracellular signaling pathways involved in neuronal excitability, inflammation, and epigenetic regulation, which may contribute to its exacerbation of kainate-induced neurotoxicity. In contrast, p57-68 appears to exert its effects through different mechanisms. Further research is necessary to elucidate the precise mechanisms by which these peptides influence neurotoxicity and understand their implications for neurological disorders.