Pyridoxal 5'-phosphate (PLP) deficiency might contribute to the onset of type I diabetes

The incidence of type I diabetes is rising worldwide, particularly in young children. Type I diabetes is considered a multifactorial disease with genetic predisposition and environmental factors participating. Currently, despite years of research, there is no consensus regarding the factors that initiate the autoimmune response. Type I diabetes is preceded by autoimmunity to islet antigens, among them the protein glutamic acid decarboxylase, GAD-65. Pyridoxal 5'-phosphate (PLP) is formed from vitamin B6 by the action of pyridoxal kinase. Interaction of GAD65 with PLP is necessary for GAD65-mediated synthesis of the neurotransmitter γ-aminobutyric acid (GABA). PLP is also a required cofactor for dopamine synthesis by L-aromatic decarboxylase (L-AADC). Both GAD65 and L-AADC are expressed in pancreatic islets. Here it is proposed that lack of the vitamin B6 derivative pyridoxal 5'-phosphate might contribute to the appearance of pancreatic islet autoimmunity and type I diabetes onset.