Jianbin Sun

Alu RNA accumulation in hyperglycemia augments oxidative stress and impairs eNOS and SOD2 expression in endothelial cells.

Endothelial dysfunction resulting from oxidative stress and inflammation plays a dominant role in hyperglycemia-induced vasculopathy. While double-stranded RNA (dsRNA) accumulates in redox and inflammatory conditions, its precise role in hyperglycemia-associated endothelial dysfunction remains unclear. This study aimed to investigate whether and how endogenous dsRNA contributes to endothelial dysfunction via oxidative stress. We used a dsRNA-specific antibody J2 to detect and immunoprecipitate cellular dsRNA. Acquired dsRNA was recognized by cDNA library construction and DNA sequencing. Quantitative PCR, ELISA and immunoassays were performed to identify changes induced by acquired dsRNA in primary human umbilical vein endothelial cells (HUVEC). Our data showed that endogenous dsRNA homologous to Alu Sc subfamily accumulated in hyperglycemic HUVEC. Comparing Alu-transfected HUVEC with high-glucose treated HUVEC, we found that Alu RNA elicited the production of reactive oxygen species (ROS) and up-regulated interleukin-1β (IL-1β) expression and secretion in a similar manner as high-glucose treatment. Moreover, Alu RNA impeded the expression of endothelial nitric oxide synthase (eNOS) and superoxide dismutase 2 (SOD2), increased ROS production and activated nuclear factor NFκB by chemically scavenging ROS and inactivation of NFκB. The repressed expression of eNOS and SOD2 resulted from Alu RNA-mediated negative regulatory mechanisms. Our study uncovered endogenous Alu RNA accumulation in hyperglycemic endothelial cells that provoked endothelial oxidative stress and dysfunction by suppressing SOD2 and eNOS expression at both transcription and translation levels via NFκB signaling pathway. These findings suggest a novel regulatory mechanism that involves endogenous dsRNA in endothelial oxidative stress and dysfunction.

A novel IgM–H-Ficolin complement pathway to attack allogenic cancer cells in vitro

The pentameric serum IgMs are critical to immune defense and surveillance through cytotoxicity against microbes and nascent cancer cells. Ficolins, a group of oligomeric lectins with an overall structure similar to C1q and mannose-binding lectin (MBL) participate in microbe infection and apoptotic cell clearance by activating the complement lectin pathway or a primitive opsonophagocytosis. It remains unknown whether serum IgMs interplay with ficolins in cancer immunosurveillance. Here we report a natural cancer killing of different types of cancer cells by sera from a healthy human population mediated by a novel IgM–H-ficolin complement activation pathway. We demonstrate for the first time that H-ficolin bound to a subset of IgMs in positive human sera and IgM–H-ficolin deposited on cancer cells to activate complement attack in cancer cells. Our data suggest that the IgM–H-ficolin -mediated complement activation pathway may be another defensive strategy for human cancer immunosurveillance.

Anti-inflammatory and neuroprotective effects of sanguinarine following cerebral ischemia in rats

Stroke is one of the leading causes of mortality worldwide. Protective agents that can diminish injuries caused by cerebral ischemia-reperfusion (I/R) are important in alleviating the harmful outcomes of stroke. The aim of the present study was to investigate the protective role of sanguinarine in cerebral I/R injury. A rat middle cerebral artery occlusion model was used to assess the clinical effect of sanguinarine, and inflammatory cytokines in the serum were detected by ELISA. Western blotting was performed to examine the change in levels of apoptosis-associated proteins in the injured brains. The results suggested that sanguinarine, an anti-inflammatory agent derived from the roots of Sanguinaria canadensis, improved the state of cerebral ischemia in a rat model. The data demonstrated that when rats were treated with sanguinarine prior to middle cerebral artery occlusion, the infarct volume was reduced significantly. The inflammatory factors tumor necrosis factor-α, interleukin (IL)-6 and IL-1β were measured in sanguinarine and vehicle-treated groups using an enzyme-linked immunosorbent assay, and the expression levels of the three factors were significantly reduced following treatment with sanguinarine (P<0.05). In addition, western blot analysis demonstrated that the ratio of B-cell lymphoma 2/Bcl-2-associated X protein was significantly increased following treatment with sanguinarine (P<0.05). The study demonstrated that sanguinarine exerts a protective effect in cerebral ischemia, and that this effect is associated with the anti-inflammatory and anti-apoptotic properties of sanguinarine.

Activation of innate antiviral immune response via double-stranded RNA-dependent RLR receptor-mediated necroptosis

Viruses induce double-stranded RNA (dsRNA) in the host cells. The mammalian system has developed dsRNA-dependent recognition receptors such as RLRs that recognize the long stretches of dsRNA as PAMPs to activate interferon-mediated antiviral pathways and apoptosis in severe infection. Here we report an efficient antiviral immune response through dsRNA-dependent RLR receptor-mediated necroptosis against infections from different classes of viruses. We demonstrated that virus-infected A549 cells were efficiently killed in the presence of a chimeric RLR receptor, dsCARE. It measurably suppressed the interferon antiviral pathway but promoted IL-1β production. Canonical cell death analysis by morphologic assessment, phosphatidylserine exposure, caspase cleavage and chemical inhibition excluded the involvement of apoptosis and consistently suggested RLR receptor-mediated necroptosis as the underlying mechanism of infected cell death. The necroptotic pathway was augmented by the formation of RIP1-RIP3 necrosome, recruitment of MLKL protein and the activation of cathepsin D. Contributing roles of RIP1 and RIP3 were confirmed by gene knockdown. Furthermore, the necroptosis inhibitor necrostatin-1 but not the pan-caspase inhibitor zVAD impeded dsCARE-dependent infected cell death. Our data provides compelling evidence that the chimeric RLR receptor shifts the common interferon antiviral responses of infected cells to necroptosis and leads to rapid death of the virus-infected cells. This mechanism could be targeted as an efficient antiviral strategy.

The Influence of PSCA Gene Variation on Its Expression and Gastric Adenocarcinoma Susceptibility in the Northwest Chinese Population

Gastric adenocarcinoma (GAC) imposes a considerable health burden around the world. Gene variation in prostate stem cell antigen gene (PSCA) has been identified to be associated with GAC risk, while the results showed regional variation. To explore the influence of PSCA gene variation on its expression and GAC risk in the Northwest Chinese population, four single nucleotide polymorphisms (SNPs) of PSCA were genotyped in 476 GAC cases and 481 controls using MassARRAY system. Two SNPs of rs2294008 (C>T) and rs2976392 (G>A) were identified to be associated with GAC risk. rs2294008, rs2976392 and rs10216533 made up two statistically significant haplotypes (Hap-CGG and Hap-TAG). Additionally, PSCA expression was analyzed by quantitative real time PCR, immunohistochemistry and tissue microarray. The results showed that PSCA expression was decreased in GAC tissues compared with adjacent normal tissues. For normal tissues, PSCA expression was higher with Hap-TA than that with Hap-CG. For GAC tissues, the differentiation degree of Hap-TA was higher than that of Hap-CG. The expression distribution of PSCA in multiple human organs showed disparity. These results suggest that PSCA gene variation has a potential effect on its expression and GAC risk in the Northwest Chinese population.

H-Ficolin-IgM initiates complement-dependent attack against cancer cells

The pentameric serum IgMs are critical to immune defense and surveillance through cytotoxicity against microbes and nascent cancer cells. Ficolins, a group of oligomeric lectins with an overall structure similar to C1q and mannose-binding lectin (MBL) participate in microbe infection and apoptotic cell clearance by activating the complement lectin pathway or a primitive opsonophagocytosis. It remains unknown whether serum IgMs interplay with ficolins in cancer immunosurveillance. Here we report a natural cancer killing of different types of cancer cells by sera from a healthy human population mediated by a novel IgM–H-ficolin complement activation pathway. We demonstrate for the first time that H-ficolin bound to a subset of IgMs in positive human sera and IgM–H-ficolin deposited on cancer cells to activate complement attack in cancer cells. Our data suggest that the IgM–H-ficolin -mediated complement activation pathway may be another defensive strategy for human cancer immunosurveillance.