NPPA and schizophrenia: In line with the above notion, it has also been suggested that circulating regulatory T cells (Tregs) could contribute to impaired glial cell functioning in schizophrenia (i.e. astroglial over-activation, microglial-mediated synaptic pruning)75, and therefore to disrupted neuro-immune mechanisms that potentially result to central alterations of KP metabolites and dysregulated neurotransmission processes.