growth factors such as insulin-like growth factor 1 (IGF-1) or T3 [21,22] which have been shown to promote remyelination efficiency in EAE even the precise molecular mechanisms remain unclear. Regarding the pathophysiology of MS and/or EAE, it has been shown that active CD4+ T cells may trigger local neuroinflamma- tion and further induce demyelination [3]. In our study, we provide morphological evidences demonstrating that CD4+ T cells are harmful for OLs lineage as neither OLs nor MBP expression can be detected around the lesion area with the accumulation CD4+ T cells (Fig. 3–5). Que treatment, however, reduces the infiltration of CD4+ T as well as the activation of microglial and astroglial in the spinal cord of EAE mice (Fig. 6). Although the inhibitory effect of Que on microglial activation has been described in the cuprizone induced demyelination mouse model [16], our current data provide further evidence to suggest that Que has the potential capacity to reduce microglial and astroglial activation, and decrease myelin-specific T cells infiltration. In respect with the decrease of T cell infiltration, does it due to an inhibited local immune response in CNS or alternatively a decreased effector T cell generation in peripheral immune organs? As in MS and EAE, the generation of myelin protein-specific T cells has been considered as a hallmark that triggering local inflammation and demyelination. A number of drugs, such as glatiramer acetate (GA) or lithium have been found to decrease the generation of myelin protein-specific T cells that contribute to their therapeutic effect on MS or EAE [10,23]. In our study, we demonstrate that both CD4+ and CD8+ cell populations decreased in peripheral immune organs after Que treatment (Fig. 4B). Moreover, we found that Que inhibited either MOG35–55-specific immunoresponse or CD3 Ab induced non-specific T cell proliferation and the transcriptional level of IL-2 (Fig. 4C–F), a crucial cytokine to initiate and maintain T cell proliferation [24,25]. Therefore, the decreased infiltration of CD4+/CD8+ T cells found in spinal cord after Que treatment seems mainly due to the immnunomodulatory role of Que that decreases effector T cell generation and inhibits local immunoresponsiveness. This data reveals for the first time, that Que displays an efficacy of modulating immunoreaction and may potentially be used in the treatment of other autoimmune disease beyond MS. As an atypical antipsychotic drug, what molecular mechanisms probably underlie the immunomodulatory effects? Recently, several neurotransmitters have been considered as potent immune-modulators. For instance, serotoninergic receptors are expressed by a broad range of inflammatory cell types, including dendritic cells, helper T cells, cytotoxin T cells and so on [26,27]. 5-HT can induce Ag-specific Th1 and cytotoxin T cell prolifer- ation via 5-HT receptor 2 and blockade of 5-HT receptor 1 attenuates deterioration of EAE model [26,27]. Similarly, hista- mine increases both ConA-dependent non-specific and TCR- mediated Ag-specific T cell proliferation via histamine receptor 2 and 1 respectively [28,29]. Giving that Que acts as an antagonist of multiple neurotransmitter receptors, including serotonin 5- HT(1A), 5-HT(2A), dopamine D(1), D(2), histamine H(1), adrenergic alpha(1) and alpha(2) receptors [30,31], it is possible that the antagonistic effect of Que on 5-HT receptors or other a References Que Inhibits T Cell Proliferation broad range receptors may contribute to its immune-modulatory effect, especially the inhibition of effector T cell proliferation. To substantiate this speculation, extensive immunological experiments are required in further studies. The finding that the beneficial efficacy of Que on EAE mice is particularly relevant to clinical studies, in that some patients with MS also display a variety of psychiatric symptoms, including depression or cognitive dysfunction [32], and some antipsychotic drugs, or antidepressants have been used to treat these symptoms. For example, fluoxetine, an antidepressant, has been effective in reducing lesions in relapsing MS patients [33]. Morever, oligodendrocyte dysfunction or demyelination has recently been implicated in the pathophysiology of schizophrenia, bipolar disorder and major depression [12,34,35]. Interestingly, all three disorders display major overlapping domains in their transcription profiles, especially genes involved in energy metabolism, inflam- mation and myelination [36]. Therefore, our present observations may support the notion that some psychiatric disorders such as schizophrenia, bipolar disorder or major depression may share similarities in disease mechanism with MS. In conclusion, this study demonstrates that the atypical antipsychotic drug Que exerts immunomodulatory role and prevent mice from deterioration of EAE symptoms and demye- lination. The novel effect of Que described here may lead to more effective strategies for treating not only schizophrenia, but other autoimmune diseases such as MS, and also provides new insight into pathogenesis of schizophrenia and related psychiatric disorders. Supporting Information Figure S1 Pre-treatment of Que delays the onset of EAE and relieves the symptoms. Que pre-treatment (N = 10) was initiated 7 days before immunization, delays the onset of EAE and relieves the symptoms as compared with vehicle (N = 10) (p,0.05). (TIF) Figure S2 Que decreases the proliferation of OPCs in spinal cord. Ki67 (red) and NG2 (green) double immunostaining identifies the proliferating OPCs in the spinal cord. A: Ki67/NG2 double-labeled cells (arrows) are often observed in the EAE model without Que treatment, and such cells are also present in the EAE model with Que treatment (A’), however, cell numbers are diminished as compared to EAE models without Que treatment, displayed in the magnified panels (B–E, B’–E’). Scale bar, A– F = 0.2 mm. (TIF) The antibody information. Table S1 (DOC) Author Contributions Conceived and designed the experiments: LX FM JMK XML. Performed the experiments: FM SG YTH LYW HKW JQN. Analyzed the data: FM SG LX. Contributed reagents/materials/analysis tools: FM SG LX YW. Wrote the paper: LX FM JMK XML SG. 1. Bitsch A, Schuchardt J, Bunkowski S, Kuhlmann T, Bruck W (2000) Acute axonal injury in multiple sclerosis. Correlation with demyelination and inflammation. Brain 123: 1174–83. 2. Dutta R, Chang A, Doud MK, Kidd GJ, Ribaudo MV, et al. (2011) Demyelination causes synaptic alterations in hippocampi from multiple sclerosis patients. Ann Neurol 69: 445–54. 3. Fletcher JM, Lalor SJ, Sweeney CM, Tubridy N, Mills KH (2010) T cells in multiple sclerosis and experimental autoimmune encephalomyelitis. Clin Exp Immunol 162: 1–11. 4. Jones RE, Bourdette DN, Offner H, Vandenbark AA (1990) Myelin basic protein-specific T cells induce demyelinating experimental autoimmune encephalomyelitis in Buffalo rats. J Neuroimmunol, 30: 61–9. PLOS ONE | www.plosone.org 9 August 2012 | Volume 7 | Issue 8 | e42746