Neuroprotection of interleukin-6 against NMDA-induced neurotoxicity is mediated by JAK/STAT3, MAPK/ERK, and PI3K/AKT signaling pathways.

We have previously shown that interleukin-6 (IL-6) has neuroprotective effect against N-methyl-D-aspartate (NMDA)-induced excitotoxicity. The current study aimed to reveal signal transduction pathways involved in the IL-6 neuroprotection. Cerebellar granule neurons (CGNs) from postnatal 8-day infant rats were exposed to IL-6 (120 ng/ml) for 8 days and stimulated with NMDA (100 µM) for 15 or 30 min. Dynamic intracellular Ca(2+) fluorescence intensity, cytosolic Ca(2+)-dependent phospholipase A2 (cPLA2) expression, and apoptosis and necrosis in cultured CGNs were measured by laser scanning confocal microscope, real-time PCR and Western blot, and annexin V-FITC/propidium iodide staining, respectively. NMDA stimulation of neurons evoked an intracellular Ca(2+) overload, an upregulated expression of cPLA2, and an increase in cell death. Chronic IL-6 exposure prevented the NMDA-evoked neuronal Ca(2+) overload, cPLA2 expression upregulation, and apoptosis and necrosis. Anti-gp130 monoclonal antibody (mAb), a blocker of gp130 that is a 130-kDa signal-transducing ß-subunit of IL-6 receptor complex, blocked these effects of IL-6 preventing NMDA neurotoxicity. AG490, PD98059, or LY294002, inhibitors specific for the intracellular signals, JAK, MAPK, and PI3K, respectively, partially blocked these IL-6 neuroprotective effects. Phosphorylation levels of STAT3, ERK1/2, and AKT, the downstream proteins for these enzymes of JAK, MAPK, and PI3K, respectively, were elevated by IL-6 pretreatment. The enhanced activation of STAT3, ERK1/2, and AKT by IL-6 was abolished by AG490, PD98059, and LY294002, respectively. Anti-gp130 mAb attenuated the activation of all the three detected signaling molecules. The present findings suggest that IL-6 neuroprotection is jointly mediated by the cellular signal transduction pathways, gp130-JAK-STAT3, gp130-MAPK-ERK, and gp130-PI3K-AKT.

Lymphocyte-derived catecholamines induce a shift of Th1/Th2 balance toward Th2 polarization.

AIMS: Our previous work has shown that lymphocytes synthesize and secrete catecholamines (CAs), which regulate lymphocyte proliferation and apoptosis. In the present study, we explored the effect of the lymphocyte-derived CAs on differentiation and function of T helper (Th) cells. METHODS: Lymphocytes were separated from the mesenteric lymph nodes of mice and stimulated by concanavalin A (Con A). These cells were treated with alpha-methyl-p- tyrosine (α-MT), an inhibitor of tyrosine hydroxylase (TH) that is a rate-limiting enzyme for synthesis of CAs, and pargyline, an inhibitor of monoamine oxidase that degrades CAs. RESULTS: Treatment of Con A-stimulated lymphocytes with α-MT (10(-6) M) reduced CAs both in the cultured lymphocytes and in the culture supernatants. Simultaneously, α-MT upregulated expression of mRNAs and proteins of T-box expressed in T cells (T-bet) and interferon-γ (IFN-γ) but downregulated expression of mRNAs and proteins of GATA binding protein 3 (GATA-3) and interleukin-4 (IL-4) in Con A-activated lymphocytes. In contrast, pargyline (10(-6) M) increased intracellular and supernatant CA contents in Con A-activated lymphocytes. Meanwhile, the treatment with pargyline downregulated expression of T-bet and IFN-γ but upregulated expression of GATA-3 and IL-4 in these lymphocytes. CONCLUSION: CAs synthesized and secreted by lymphocytes regulate differentiation and function of Th cells, with an effect facilitating the shift of Th1/Th2 balance toward Th2 polarization.

The hypothalamus mediates the effect of cerebellar fastigial nuclear glutamatergic neurons on humoral immunity.

OBJECTIVES: We explored effect of glutamatergic neurons in the fastigial nucleus (FN), one of three cerebellar nuclei, on humoral immunity and revealed that this effect was mediated by the hypothalamus via FN-hypothalamic glutamatergic transmission. METHODS: Rats were immunized with bovine serum albumin (BSA). On the third day after the immunization, 6-diazo-5-oxo-L-norleucine (DON), an inhibitor of glutaminase for glutamate synthesis, was microinjected in bilateral FN and D,L-threo-ß-hydroxyaspartic acid (THA), an inhibitor of glutamate transporters on plasma membrane, was microinjected in both sides of lateral hypothalamic area (LHA). Glutamate content in the hypothalamus was examined by high-performance liquid chromatography (HPLC). Flow cytometry and enzyme-linked immunosorbent assay (ELISA) were used to measure B lymphocyte percentage in mononuclear cells of peripheral blood and levels of anti-BSA IgM and IgG antibodies in the serum, respectively. RESULTS: DON injection in bilateral FN reduced B lymphocyte percentage and anti-BSA IgM and IgG levels, and simultaneously decreased glutamate content in the hypothalamus. Combined treatment with DON in the FN and with THA in the LHA elevated B cell number and anti-BSA IgM and IgG levels and increased hypothalamic glutamate content compared with DON treatment alone. However, combined treatment with DON in the FN and with THA in the ventrolateral thalamic nuclei (VL) did not significantly alter DON-dependent changes in B cell number and antibody levels, although the co-treatment altered DON-dependent glutamate content in the thalamus. CONCLUSION: Cerebellar FN glutamatergic neurons participate in modulation of humoral immunity and this effect is mediated by the hypothalamus via FN-hypothalamic glutamatergic transmission.

[Expression of CAR in myocardial of viral myocarditis and dilated cardiomyopathy].

OBJECTIVE: In order to improve accuracy and reliability of forensic diagnosis of sudden cardiac death, pathogenesis and relationship between the viral myocarditis (VMC) and dilated cardiomyopathy (DCM) were investigated. METHODS: Improved immunohistochemical technique was used to detect the expression of the CAR in myocardium samples, including 22 deceased with VMC, 20 deceased with DCM and 16 control deceased. RESULTS: The brown staining on the cell membrane of myocardium showed positive result. There was a prominent CAR expression in VMC group and DCM group, which were statistically significant difference compared with control group (P < 0.05). CONCLUSION: The CAR expression showed significantly higher in VMC and DCM groups. The viral infection can result in myocardial necrosis and impaired cardiac functions. These abnormalities can trigger a cascade of events that contributed to the progress of VMC to DCM.

[Effect of matrine on regulating renal tubulointerstitial expression of MMP-3, TIMP-1 and FN].

OBJECTIVE: To explore the effect and mechanism of matrine on regulating renal tubulointerstitium expression of MMP-3, TIMP-1 and FN. METHODS: Seventy male SD rats were randomly allocated to five groups: normal group, shame UUO group, UUO group, UUO group treated with fusinopril (F group), UUO group treated with large dose of matrine (E group) and UUO group treated with small dose of matrine (D group). The expression levels of MMP-3, TIMP-1 and FN of the rats were determined with immunohistochemistry at 7, 14 days of the experiment. RESULTS: The expression levels of MMP-3 of the rats in the UUO group and treatment groups decreased significantly compared with the normal group and shame UUO group (P<0.05). The treatment groups had higher expression of MMP-3 than that of the UUO group (P< 0.05). The expression levels of TIMP-1 and FN of the rats in the normal group and shame UUO group were amongst the lowest. The treatment groups had lower expression of TIMP-1 and FN than that of the UUO group (P<0.05). No significant difference of expression of MMP-3, FN and TIMP-1 were found between E group and F group (P>0.05). The expression level of MMP-3 was negatively correlated with those of TIMP-1 and FN in the UUO group (P < 0.01). CONCLUSION: Matrine decreases the expression of TIMP-1 and FN in the tubulointerstitium and increases the expression of MMP-3, which would delay the progression of renal tubulointerstitial fibrosis.