Phenylmethimazole Suppresses dsRNA-Induced Cytotoxicity and Inflammatory Cytokines in Murine Pancreatic Beta Cells and Blocks Viral Acceleration of Type 1 Diabetes in NOD Mice

Article (PDF Available)inMolecules 18(4):3841-3858 · April 2013with20 Reads
DOI: 10.3390/molecules18043841 · Source: PubMed
Accumulating evidence supports a role for viruses in the pathogenesis of type 1 diabetes mellitus (T1DM). Activation of dsRNA-sensing pathways by viral dsRNA induces the production of inflammatory cytokines and chemokines that trigger beta cell apoptosis, insulitis, and autoimmune-mediated beta cell destruction. This study was designed to evaluate and describe potential protective effects of phenylmethimazole (C10), a small molecule which blocks dsRNA-mediated signaling, on preventing dsRNA activation of beta cell apoptosis and the inflammatory pathways important in the pathogenesis of T1DM. We first investigated the biological effects of C10, on dsRNA-treated pancreatic beta cells in culture. Cell viability assays, quantitative real-time PCR, and ELISAs were utilized to evaluate the effects of C10 on dsRNA-induced beta cell cytotoxicity and cytokine/chemokine production in murine pancreatic beta cells in culture. We found that C10 significantly impairs dsRNA-induced beta cell cytotoxicity and up-regulation of cytokines and chemokines involved in the pathogenesis of T1DM, which prompted us to evaluate C10 effects on viral acceleration of T1DM in NOD mice. C10 significantly inhibited viral acceleration of T1DM in NOD mice. These findings demonstrate that C10 (1) possesses novel beta cell protective activity which may have potential clinical relevance in T1DM and (2) may be a useful tool in achieving a better understanding of the role that dsRNA-mediated responses play in the pathogenesis of T1DM.
    • "These molecules are important players in TLR4 and TLR3 signaling [Takeda et al., 2003; Akira and Takeda, 2004; Kawai and Akira, 2005; Heo et al., 2008]. Our group had previously shown C10 exhibits inhibition of TLR (TLR3 and TLR4) expression and signaling in immune and non-immune cells and is protective against ensuing inflammatory diseases [Dagia et al., 2004; Harii et al., 2005; McCall et al., 2007 McCall et al., , 2010 McCall et al., , 2013 Schwartz et al., 2009; Benavides et al., 2010 Benavides et al., , 2011. More specifically, our group has also shown that C10 can inhibit the expression of TLR4 and the resultant production of pro-inflammatory cytokines and and C10 (0–500 μM, using serial dilutions) for 4 h. "
    [Show abstract] [Hide abstract] ABSTRACT: Preclinical ResearchPhenylmethimazole (C10) is an inhibitor of Toll-like receptor (TLR3 and TLR4) expression and signaling. In this study, we carried out a detailed investigation of the effect of C10 on TLR4 and its molecular signaling products in RAW 264.7 macrophages using quantitative real-time polymerase chain reaction (PCR), ELISA and cell toxicity assays, a set of in vitro assays that may be used to screen future C10 analogs. C10 exhibited an inhibitory effect on TLR4 MyD88-dependent and MyD88-independent pathways. Within the TLR4 pathway, C10 inhibited the expression of cytokines, cytokine receptors, kinases, adapter molecules and transcription factors, suggesting a pathway-wide inhibitory effect. We also found that C10 dose-dependently inhibited the expression of TLR4 signaling products, specifically IL-6, inducible nitric oxide (NO) synthase and IFNβ. Additionally, pre-treatment of RAW 264.7 cells with C10 resulted in protection from lipopolysaccharide (LPS) insults, suggesting C10 may be bound to the target thus exhibiting activity during/following LPS stimulation. Also, dimethyl sulfoxide, the solvent for C10 exhibited inhibitory effect on TLR4 signaling products independent from the effects of C10. Combined, this study enhances understanding of the actions of action on TLR4 signaling pathway providing a path for the development of new C10 analogs for inhibiting TLR expression and signaling.
    Full-text · Article · Dec 2014
    • "Type 2 diabetes (T2DM) is becoming a serious threat to human health in all parts of the World, placing an enormous burden on national healthcare systems, particularly in developing countries [1,2]. Modernized lifestyles featured by over-nutrition and less-exercise stimulate the increase in the prevalence of obesity and associated metabolic disorders including T2DM. "
    [Show abstract] [Hide abstract] ABSTRACT: Sophoricoside, an isoflavone glycoside isolated from Sophora japonica (Leguminosae), has been widely reported as an immunomodulator. In this study, the effects of sophoricoside on lipogenesis and glucose consumption in HepG2 cells and C2C12 myotubes were investigated. Treatment with sophoricoside at concentrations of 1-10 μM inhibited lipid accumulation in HepG2 cells in a dose-dependent manner. At the same concentration range, no effect on cell viability was observed in the MTT assay. Inhibition of lipogenesis was associated with the downregulation of SREBP-1a, SREBP-1c, SREBP-2 and their downstream target genes (FAS, ACC, HMGR) as revealed by realtime quantitative PCR. The lipid-lowering effect was mediated via the phosphorylation of AMPK. Further investigation of the activities of this isoflavone showed that sophoricoside has the capability to increase glucose uptake by C2C12 myotubes. It also effectively inhibited the activities of α-glucosidase and α-amylase in vitro and remarkably lowered postprandial hyperglycaemia in starch-loaded C57BL6/J mice. These results suggest that sophoricoside is an effective regulator of lipogenesis and glucose consumption and may find utility in the treatment of obesity and type 2 diabetes.
    Full-text · Article · Dec 2013
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