Increase in dopaminergic, but not serotoninergic, receptors in T-cells as a marker for schizophrenia severity.

Schizophrenia is characterized by a slow deteriorating mental illness. Although the pathophysiology mechanisms are not fully understood, different studies have suggested a role for the immune system in the pathogenesis of schizophrenia. To date, an altered expression or signaling of neurotransmitters receptors is observed in immune cells during psychiatric disorders. In the present study, we investigated the expression of different serotonin and dopamine receptors in T-cells of schizophrenic and control patients. We used flow cytometry to determine the pattern of expression of dopamine (D2 and D4) and serotonine receptors (SR1A, SR1C, SR2A, SR2B), as well as serotonin transporter (ST), in T-cell subsets (CD4 and CD8). Expression of serotonin receptors and ST in T-cells of schizophrenic patients were not different from controls. However, the percentages of CD4+D4+ and CD8+D4+ were increased in schizophrenic patients as compared to controls. In addition, increased percentages of CD8+D2+ cells were also observed in schizophrenic patients, albeit this population revealed lower CD4+D2+ cells in comparison to controls. Interestingly, a relationship between clinical symptoms and immunological parameters was also observed. We showed that the Brief Psychiatric Rating Scale (BPRS), the Positive and Negative Syndrome Scale (PANSS) and the Abnormal Involuntary Movement Scale (AIMS) were positively related to CD8+D2+ cells, though AIMS was inversely related to CD4+D4+ cells. In conclusion, the alteration in the pattern of cell population and molecules expressed by them might serve as a promising biomarker for diagnosis of schizophrenia.

The crude latex of Euphorbia tirucalli modulates the cytokine response of leukocytes, especially CD4+ T lymphocytes

The plants of the Euphorbiaceae family, especially those of the genus Euphorbia, are frequently used by Brazilian folk communities to treat a wide variety of infectious, tumoral and inflammatory illnesses. Among the species of this genus, Euphorbia tirucalli L. is widely used in some Brazilian regions, such as the Jequitinhonha River Valley. There is evidence that the latex produced by E. tirucalli has antiviral and antitumor activities, but little is known about the mechanisms involved in these effects. It is likely that the mechanism for such activities involves leukocyte activation and cytokine production. In this work, we aimed to evaluate the production of type 1 (TNF-α and IFN-γ) and type 2 (IL-4 and IL-10) cytokines by circulating leukocyte subsets submitted to brief stimulation with the crude latex of E. tirucalli. Peripheral blood leukocytes of twenty healthy subjects were submitted to 4 h incubation with crude E. tirucalli latex diluted in dimethylsulfoxide. After the incubation period, the cells were stained with FITC-conjugated monoclonal antibodies specific to the cell surface receptors CD4, CD8 and CD14, and to PE-conjugated monoclonal antibodies specific to the cytokines TNF-α, IFN-γ, IL-4 and IL-10. The acquisition and analysis of data were performed by flow cytometry. The results showed a significant increase (p<0.05) in the percentage of CD4+ T lymphocytes positive for the type 1 cytokines TNF-α and IFN-γ. Neutrophils and CD8+ T lymphocytes showed a mixed profile of cytokine production, characterized by an increase in the percentage of cells expressing IFN-γ, TNF-α, and IL-10. The data indicate a predominant type 1 cytokine response. The findings presented suggest that the effect popularly attributed to E. tirucalli usage may be attributed to its effect on the production of TNF-α and IFN-γ. However, the relationship between the in vitro and in vivo effects of E. tirucalli needs to be investigated.