medication – Toxoplasma gondii & Human Phenotype

Autism spectrum disorders may be due to cerebral toxoplasmosis associated with chronic neuroinflammation causing persistent hypercytokinemia that resulted in an increased lipid peroxidation, oxidative stress, and depressed metabolism of endogenous and exogenous substances

October 19, 2010
Prandota J.
Research in Autism Spectrum Disorders 2010; 4: 119-155

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Worldwide, approximately 2 billion people are chronically infected with Toxoplasma gondii with largely yet unknown consequences. Patients with autism spectrum disorders (ASD) similarly as mice with chronic toxoplasmosis have persistent neuroinflammation, hypercytokinemia with hypermetabolism associated with enhanced lipid peroxidation, and extreme changes in the weight resulting in obesity or wasting. Data presented in this review suggest that environmental triggering factors such as pregnancy, viral/bacterial infections, vaccinations, medications, and other substances caused reactivation of latent cerebral toxoplasmosis because of changes in intensity of latent central nervous system T. gondii infection/inflammation and finally resulted in development of ASD. Examples of such environmental factors together with their respective biomarker abnormalities are: pregnancy (increased NO, IL-1 beta, TNF-alpha, IL-6, IL-10, prolactin: decreased IFN-gamma, IL-12), neuroborreliosis (increased IL-1 beta, sIL-1R2, TNF-alpha, IFN-gamma, IL-6, IL-10, IL-12, IL-18, transforming growth factor-beta 1 (TGF-beta 1)), vital infections (increased IL-1 beta, IL-6, IL-8, TNF-alpha, IFN-gamma/alpha/beta,TGF-beta 1), thimerosal (increased IL-5, IL-13; decreased IFN-gamma,TNF-alpha,IL-6, IL-12p70, NOS), and valproic acid (increased NO, reactive oxygen species; decreased TNF-alpha, IL-6, IFN-gamma). The imbalances in pro- and antiinflammatory processes could markedly hinder [lost defense mechanisms important for immune control of the parasite, such as the production of NO, cytokines, and reactive oxygen/nitrogen species, tryptophan degradation by indoleamine 2,3-dioxygenase and/or tryptophan 2,3-dioxygenase, limitation of the availability of intracellular iron to T gondii, and the mechanisms mediated by an IFN-gamma responsive gene family. These fluctuations could result in a recurrent profuse multiplication of T. gondii in the brain associated with persistent neuroinflammation, chronic overproduction of pro- and antiinflammatory cytokines, and NO causing increased oxidative stress, and significantly depressed activity of several enzymes including cytochrome P450 monooxygenase family responsible for metabolism of physiological substrates and xenobiotics, such as steroids, fatty acids, prostaglandins, drugs, pollutants, and carcinogens, finally leading to development of ASD. This reasoning may be supported by such abnormal metabolic events as: (1) patients with ASD have significantly decreased melatonin levels caused by marked deficit in acetylserotonin methyltransferase activity, possibly resulting from maternal and/or fetal/postnatal overproduction of NO, characteristic for this clinical entity; (2) thimerosal inhibited both insulin-like growth factor-1- and dopamine-stimulated methylation reactions, and depressed methionine synthase activity, the metabolic events important for promoting normal neurodevelopment; (3) valproic acid, a strong histone deacetylase inhibitor, have potent anti-T. gondii activity. Thus, patients with ASD should be tested for T. gondii infection. (C) 2009 Elsevier Ltd. All rights reserved

Parasites as causative agents of human affective disorders? The impact of anti-psychotic, mood-stabilizer and anti-parasite medication on Toxoplasma gondii ‘s ability to alter host behaviour

October 30, 2006
Webster, J.P., Lamberton, P.H.L., Donnelly, C.A., Torrey, E.F.
Proceedings of the Royal Society B-Biological Sciences 2006; 273: 1023-1030

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With increasing pressure to understand transmissible agents, renewed recognition of infectious causation of both acute and chronic diseases is occurring. Epidemiological and neuropathological studies indicate that some cases of schizophrenia may be associated with environmental factors, such as exposure to the ubiquitous protozoan Toxoplasma gondii. Reasons for this include T gondii's ability to establish persistent infection within the central nervous system, its ability to manipulate intermediate host behaviour, the occurrence of neurological and psychiatric symptoms in some infected individuals, and an association between infection with increased incidence of schizophrenia. Moreover, several of the medications used to treat schizophrenia and other psychiatric disease have recently been demonstrated in vitro to possess antiparasitic, and in particular anti-T gondii, properties. Our aim here was thus to test the hypothesis that the anti-psychotic and mood stabilizing activity of some medications may be achieved, or at least augmented, through their in vivo inhibition of T gondii replication and invasion in infected individuals. In particular we predicted, using the epidemiologically and clinically applicable rat-T gondii model system, and following a previously described and neurologically characterized 'feline attraction' protocol that haloperidol (an antipsychotic used in the treatment of mental illnesses including schizophrenia) and/or valproic acid (a mood stabilizer used in the treatment of mental illnesses including schizophrenia), would be, at least, as effective in preventing the development of T gondii-associated behavioural and cognitive alterations as the standard anti-T gondii chemotherapeutics pyrimethamine with Dapsone. We demonstrate that, while T gondii appears to alter the rats' perception of predation risk turning their innate aversion into a 'suicidal' feline attraction, anti-psychotic drugs prove as efficient as anti-T gondii drugs in preventing such behavioural alterations. Our results have important implications regarding the aetiology and treatment of such disorders.