Toxoplasma Immunomodulation Related to Neuropsychiatric Diseases

Abstract

Toxoplasma gondii (T. gondii) causes toxoplasmic encephalitis resulting from reactivation of latent toxoplasmosis. It is the most frequent clinical manifestation, characterized by multiple necrotizing brain lesions. Bradyzoite tissue cysts activate an immune response that has a major impact on controlling parasite persistence in the brain. The immune mechanisms stimulated in the brain cause a local inflammatory mediated by Th1 immune reaction cytokines. Several studies have linked this process to that active during different neuropsychiatric disorders, such as Schizophrenia. In addition to the immune reaction activated in the brain, this latter has the capacity to stimulate neurotransmitter production. T. gondii induces high concentrations of dopamine and tyrosine hydroxylase in the central nervous system and has also been shown to increase kynurenine/tryptophan ratio and elevated Kynurenic acid level, mainly in astrocyte cells. This imbalance plays a role in the pathophysiology of Schizophrenia. Results of different studies explain in this chapter support the idea that Toxoplasma is an etiological factor in Schizophrenia.