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Deterioration of inhibitory synapse may be an essential neurological basis underlying abnormal social behaviours. Manipulations that regulate GABAergic transmission are associated with improved behavioural phenotypes in sociability. The synaptic protein, Ephrin-B2 (EB2), plays an important role in the maintenance and reconfiguration of inhibitory synapses in the medial prefrontal cortex (mPFC). However, the inhibitory cell-type specific role of EB2 in the pathophysiology and treatment of social deficits remains unknown. As expected, we revealed that tdTomato-expressing cells were only found in GABAergic neurons instead of excitatory neurons in transgenic EB2-vGATCre mice. This result indicated that depletion of EB2 would occur in those neurons, which further contribute to social deficits. In addition, specific over-expression of mPFC EB2 restored the defective social behaviour abnormalities. These results suggest that the effect of EB2 on social deficits is anatomically and cell-type specific. More importantly, the global upregulation of HDAC4 expression was found in EB2-vGATCre mice. Significant subcellular nuclear shuttling of HDAC4 in vGAT+ neurons was examined and quantified, suggesting a role of nuclear HDAC4 in mediating the mechanism underlying EB2 impairment in vGAT+ neurons. Treatment with LMK235 led to a remarkable rescue of social deficits, thus our data revealed a new domain for the potential utility of HDAC targeting agents to treat social deficits. In conclusion, these results not only revealed a novel molecular mechanism underlying the pathophysiology of social deficits, but also suggested a potential intervention avenue for the treatment of social deficits.

Olanzapine (OLZ) is efficacious whereas leads to adverse metabolic effects thus lead to higher risk of cardiovascular diseases (CVD) on schizophrenia. Cytokines have been found associated with metabolic disorders. Therefore, pretreatment prediction of OLZ-induced adverse metabolic effects is urgently needed. To investigate if baseline cytokine levels could become biomarkers for pathogenesis of schizophrenia or prediction for OLZ-induced adverse metabolic effects, we recruited 75 participants, including 23 schizophrenia inpatients, who were antipsychotic-free over the past 6 months or first episode and drug-naive and 52 matched health controls, in our prospective cohort study and cross-sectional study. We simultaneously examined 7 serum cytokine levels (IFN-γ, IL-1ra, IL-1β, IL-8, TNF-α, MCP-1, VEGF) before OLZ treatment by using liquid suspension array technique and obtained clinical correlates at 4-week intervals in total 8 weeks. The psychopathology was assessed with the Positive and Negative Symptom Scale (PANSS). The metabolic parameters were BMI, TG, total cholesterol, LDL, HDL, ApoA1, ApoB, lipoprotein a, fasting glucose, HbA1c, insulin, and leptin. At baseline, IL-1ra and MCP-1 levels in schizophrenia were significantly higher than health controls (t = 4.55, P = 0.0001, t = 3.08 P = 0.003). BMI, fasting insulin, cholesterol, triglyceride, LDL, ApoB and leptin were significantly increased in patients with schizophrenia after 8 weeks of olanzapine treatment. Correlation analysis showed that the baseline IL-1ra level were significantly correlated with the increased levels of cholesterol (P = 0.004), LDL (P = 0.005), ApoB (P = 0.018) and leptin (P = 0.010), but not with the increased BMI, insulin or triglycerides. Further stepwise multiple linear regression analysis indicated that IL-1ra levels prior to treatment remained significantly associated with increased levels of cholesterol, LDL, ApoB and leptin. Above all, higher IL-1ra and MCP-1 levels may be biomarkers indicating pathogenesis of schizophrenia. Higher serum levels of IL-1ra may predict subsequent higher possibility of hypercholesterolemia and hyperleptinemia following OLZ treatment in schizophrenia patients.