Fluorescent carbon nanodots (C-dots; 4.3 AE 0.8 nm) from fresh tender ginger juice provide high suppression of the growth of human hepatocellular carcinoma cells (HepG2), with low toxicity to normal mammary epithelial cells (MCF-10A) and normal liver cells (FL83B). The inhibition is selective to HepG2 over other tested cancer cells, including human lung cancer cell line (A549), human breast cancer cell line (MDA-MB-231), and human cervical cancer cell line (HeLa). Western blot results reveal that the C-dots up-regulate the expression of p53 protein only in the HepG2 cell line. The 50% inhibiting concentration (IC 50 ) value of the C-dots on HepG2 cells is 0.35 mg mL À1 . Image cytometry results show significant uptake of C-dots by HepG2 cells that induce intracellular production of reactive oxygen species (ROS, 18.2-fold increased), while other cells remain almost the same in ROS levels after treatment with C-dots (1.11 mg mL À1 ). The C-dots trigger the pro-apoptotic factor to promote HepG2 cell apoptosis. The C-dots effectively inhibit the growth of tumors in nude mice (104 AE 14 vs. 3.7 AE 0.2 mg with and without treatment within 14 days).

The immunopathogenesis mechanism of dengue virus (DV) infection remains elusive. We previously showed that the target of DV in humans is dendritic cells (DCs), the primary sentinels of immune system. We also observed that despite the significant amount of IFN-α induced; DV particles remain massively produced from infected DCs. It suggests that DV may antagonize the antiviral effect of IFN-α. Recent work in animal studies demonstrated the differential critical roles of antiviral cytokines, namely IFN-α/IFN-β and IFN-γ, in blocking early viral production and in preventing viral-mediated disease, respectively. In this study, we examined the effects of IFN-α and IFN-γ in DV infection of monocyte-derived DCs. We showed that the preinfection treatment with either IFN-α or IFN-γ effectively armed DCs and limited viral production in infected cells. However, after infection, DV developed mechanisms to counteract the protection from lately added IFN-α, but not IFN-γ. Such a selective antagonism on antiviral effect of IFN-α, but not IFN-γ, correlated with down-regulated tyrosine-phosphorylation and DNA-binding activities of STAT1 and STAT3 transcription factors by DV. Furthermore, subsequent studies into the underlying mechanisms revealed that DV attenuated IFN-α-induced tyrosine-phosphorylation of Tyk2, an upstream molecule of STAT activation, but had no effect on expression of both IFN-α receptor 1 and IFN-α receptor 2. Moreover, DV infection by itself could activate STAT1 and STAT3 through IFN-α-dependent and both IFN-α-dependent and IFN-α-independent mechanisms, respectively. These observations provide very useful messages with physiological significance in investigation of the pathogenesis, the defense mechanisms of human hosts and the therapeutic considerations in DV infection.

BackgroundDocosahexaenoic acid (DHA) and DHA-derived lipid mediators have recently been shown to possess anti-inflammatory and pro-resolving properties. In fact, DHA can down-regulate lipolysaccharide (LPS)-induced activation of NF-κB via a PPARγ-dependent pathway. We sought to investigate the effects of the novel DHA-derived mediator resolvin D1 (RvD1) on LPS-induced acute lung injury and to determine whether these effects occur via a PPARγ-dependent pathway.MethodsBALB/c mice aged 6–8 weeks were randomly divided into seven groups: two control groups receiving saline or RvD1 (600 ng) without LPS; a control group receiving LPS only; an experimental group receiving RvD1 (300 ng) or RvD1 (600 ng), followed by LPS; a group receiving the PPARγ antagonist GW9662; and a group receiving GW9662, then RvD1 (600 ng) and finally LPS. LPS (50 μM) and saline were administered intratracheally. RvD1 was injected intravenously 24 h and 30 min before LPS, while GW9662 was injected intravenously 30 min before RvD1. Mice were killed at 6, 12, and 24 h. Samples of bronchoalveolar lavage fluid (BALF) were analyzed for cell counts and cytokine analysis. Lung tissues were collected for histology, Western blotting and electrophoretic mobility shift assays (EMSAs).ResultsAt all three time points, groups receiving either dose of RvD1 followed by LPS had significantly lower total leukocyte counts and levels of TNF-α and IL-6 levels in BALF than did the group given only LPS. RvD1 markedly attenuated LPS-induced lung inflammation at 24 h, based on hematoxylin-eosin staining of histology sections. RvD1 activated PPARγ and suppressed IκBα degradation and NF-κB p65 nuclear translocation, based on Western blots and EMSAs. The PPARγ inhibitor GW9662 partially reversed RvD1-induced suppression of IκBα degradation and p65 nuclear translocation.ConclusionsThese results suggest that RvD1 may attenuate lung inflammation of LPS-induced acute lung injury by suppressing NF-κB activation through a mechanism partly dependent on PPARγ activation.