TNF-α and TGF-β synergistically stimulate elongation of human endothelial cells without transdifferentiation to smooth muscle cell phenotype

Endothelial ROBO4 suppresses PTGS2/COX-2 expression and inflammatory diseases

Accumulating evidence suggests that endothelial cells can be useful therapeutic targets. One of the potential targets is an endothelial cell-specific protein, Roundabout4 (ROBO4). ROBO4 has been shown to ameliorate multiple diseases in mice, including infectious diseases and sepsis. However, its mechanisms are not fully understood. In this study, using RNA-seq analysis, we found that ROBO4 downregulates prostaglandin-endoperoxide synthase 2 (PTGS2), which encodes cyclooxygenase-2. Mechanistic analysis reveals that ROBO4 interacts with IQ motif-containing GTPase-activating protein 1 (IQGAP1) and TNF receptor-associated factor 7 (TRAF7), a ubiquitin E3 ligase. In this complex, ROBO4 enhances IQGAP1 ubiquitination through TRAF7, inhibits prolonged RAC1 activation, and decreases PTGS2 expression in inflammatory endothelial cells. In addition, Robo4-deficiency in mice exacerbates PTGS2-associated inflammatory diseases, including arthritis, edema, and pain. Thus, we reveal the molecular mechanism by which ROBO4 suppresses the inflammatory response and vascular hyperpermeability, highlighting its potential as a promising therapeutic target for inflammatory diseases.

Toxicity of Orthodontic Brackets Examined by Single Cell Tracking

Subtle toxic effects may be masked in traditional assays that average or summate the response of thousands of cells. We overcome this by using the recent method of single cell tracking in time-lapse recordings. This follows the fate and behavior of individual cells and their progeny and provides unambiguous results for multiple simultaneous biological responses. Further, single cell tracking permits correlation between progeny relationships and cell behavior that is not otherwise possible, including disruption by toxins and toxicants of similarity between paired sister cells. Notably, single cell tracking seems not to have been previously used to study biomaterials toxicity. The culture medium was pre-conditioned by 79 days incubation with orthodontic brackets from seven separate commercial sources. Metal levels were determined by Inductively Coupled Plasma Mass Spectrometry. Metal levels varied amongst conditioned media, with elevated Cr, Mn, Ni, and Cu and often Mo, Pb, Zn, Pd, and Ag were occasionally found. The effect on human dermal fibroblasts was determined by single cell tracking. All bracket-conditioned media reduced cell division (p < 0.05), while some reduced cell migration (p < 0.05). Most bracket-conditioned media increased the rate of asynchronous sister cell division (p < 0.05), a seemingly novel measure for toxicity. No clear effect on cell morphology was seen. We conclude that orthodontic brackets have cytotoxic effects, and that single cell tracking is effective for the study of subtle biomaterials cytotoxicity.

Duality of Interactions Between TGF-β and TNF-α During Tumor Formation

The tumor microenvironment is essential for the formation and development of tumors. Cytokines in the microenvironment may affect the growth, metastasis and prognosis of tumors, and play different roles in different stages of tumors, of which transforming growth factor β (TGF-β) and tumor necrosis factor α (TNF-α) are critical. The two have synergistic and antagonistic effect on tumor regulation. The inhibition of TGF-β can promote the formation rate of tumor, while TGF-β can promote the malignancy of tumor. TNF-α was initially determined to be a natural immune serum mediator that can induce tumor hemorrhagic necrosis, it has a wide range of biological activities and can be used clinically as a target to immune diseases as well as tumors. However, there are few reports on the interaction between the two in the tumor microenvironment. This paper combs the biological effect of the two in different aspects of different tumors. We summarized the changes and clinical medication rules of the two in different tissue cells, hoping to provide a new idea for the clinical application of the two cytokines.

Interleukin 37 promotes angiogenesis through TGF-β signaling

IL-37 is a novel pro-angiogenic cytokine that potently promotes endothelial cell activation and pathological angiogenesis in our previous study, but the mechanisms behind the pro-angiogenic effect of IL-37 are less well understood. Extending our observations, we found that TGF-β interacts with IL-37, and potently enhances the binding affinity of IL-37 to the ALK1 receptor complex, thus allowing IL-37 to signal through ALK1 to activate pro-angiogenic responses. We further show that TGF-β and ALK1 are required in IL-37 induced pro-angiogenic response in ECs and in the mouse model of Matrigel plug and oxygen-induced retinopathy. The result suggests that IL-37 induces pro-angiogenic responses through TGF-β, which may act as the bridging molecule that mediates IL-37 binding to the TGF-β receptor complex.

Transcriptional Regulatory Network Analysis for Gastric Cancer Based on mRNA Microarray

We aimed to screen the differential expressed genes (DEGs) and transcriptional factors (TFs) related to gastric cancer. GSE19826 microarray data downloaded from Gene Expression Omnibus was used to identify the differentially expressed genes (DEGs) and PPI network of DEGs were constructed by the Retrieval of Interacting Genes database. Pathway enrichment analysis of DEGs were performed by Gene Set Enrichment Analysis. Then, the transcriptional regulatory network was constructed based on TRANSFAC database. Finally, regulatory impact factor (RIF) of TF was calculated. We identified 446 DEGs including 209 up- and 237 down-regulated genes. These DEGs were mainly significantly enriched in 5 pathways including ECM receptor interaction (p = 0.013899), spliceosome (p = 0.025591), bladder cancer (p = 0.026316), focal adhesion (p = 0.047809) and WNT signaling pathway (p = 0.048077). PPI network with 247 nodes and 913 edges were constructed and COL5A2 was the hub node. Transcriptional regulatory network with 6 differently expressed TFs, 58 non-differently expressed TFs, 44 DEGs and 735 non-DEGs was constructed. Finally, top 5 TFs including CRX, TFAP4, NKX2-1, MYB and RARG with higher Z_RIF were screened. The identified DEGs such as COL5A2 and TOP2A, and TFs including EGR2, FOXM1, NKX2-1 and TFAP4 might be the critical genes and TFs for gastric cancer.

Aspirin-Triggered Resolvin D1 Inhibits TGF-β1-Induced EndMT through Increasing the Expression of Smad7 and Is Closely Related to Oxidative Stress

The endothelial-mesenchymal transition (EndMT) is known to be involved in the transformation of vascular endothelial cells to mesenchymal cells. EndMT has been confirmedthat occur in various pathologic conditions. Transforming growth factor β1 (TGF-β1) is a potent stimulator of the vascular endothelial to mesenchymal transition (EMT). Aspirin-triggered resolvin D1 (ATRvD1) has been known to be involved in the resolution of inflammation,but whether it has effects on TGF-β1-induced EndMT is not yet clear. Therefore, we investigated the effects of AT-RvD1 on the EndMT of human umbilical vein vascular endothelial cells line (HUVECs). Treatment with TGF-β1 reduced the expression of Nrf2 and enhanced the level of F-actin, which is associated with paracellular permeability. The expression of endothelial marker VE-cadherin in HUVEC cells was reduced, and the expression of mesenchymal marker vimentin was enhanced. AT-RvD1 restored the expression of Nrf2 and vimentin and enhanced the expression of VE-cadherin. AT-RvD1 did also affect the migration of HUVEC cells. Inhibitory κB kinase 16 (IKK 16), which is known to inhibit the NF-kB pathway, had an ability to increase the expression of Nrf2 and was associated with the inhibition effect of AT-RvD1 on TGF-β1-induced EndMT, but it had no effect on TGF-β1-induced EndMT alone. Smad7, which is a key regulator of TGF-β/Smads signaling by negative feedback loops, was significantlyincreased with the treatment of AT-RvD1. These results suggest the possibility that AT-RvD1 suppresses the TGF-β1-induced EndMT through increasing the expression of Smad7 and is closely related to oxidative stress.

mESC-based in vitro differentiation models to study vascular response and functionality following genotoxic insults

Because of high exposure to systemic noxae, vascular endothelial cells (EC) have to ensure distinct damage defense and regenerative mechanisms to guarantee vascular health. For meaningful toxicological drug assessments employing embryonic stem cell (ESC)-based in vitro models, functional competence of differentiated progeny and detailed knowledge regarding damage defense mechanisms are essential. Here, mouse ESCs (mESC) were differentiated into functionally competent vascular cells (EC and smooth muscle cells [SMC]). mESC, EC, and SMC were comparatively analyzed regarding DNA repair and DNA damage response (DDR). Differentiation was accompanied by both congruent and unique alterations in repair and DDR characteristics. EC and SMC shared the downregulation of genes involved cell cycle regulation and repair of DNA double-strand breaks (DSBs) and mismatches, whereas genes associated with nucleotide excision repair (NER), apoptosis, and autophagy were upregulated when compared with mESC. Expression of genes involved in base excision repair (BER) was particularly low in SMC. IR-induced formation of DSBs, as detected by nuclear γH2AX foci formation, was most efficient in SMC, the repair of DSBs was fastest in EC. Together with substantial differences in IR-induced phosphorylation of p53, Chk1, and Kap1, the data demonstrate complex alterations in DDR capacity going along with the loss of pluripotency and gain of EC- and SMC-specific functions. Notably, IR exposure of early vascular progenitors did not impair differentiation into functionally competent EC and SMC. Summarizing, mESC-based vascular differentiation models are informative to study the impact of environmental stressors on differentiation and function of vascular cells.

Finding ATF4/p75NTR/IL-8 signal pathway in endothelial-mesenchymal transition by safrole oxide

Targeting the endothelial-to-mesenchymal transition (EndoMT) may be a novel therapeutic strategy for cancer and various diseases induced by fibrosis. We aimed to identify a small chemical molecule as an inducer of EndoMT and find a new signal pathway by using the inducer. Safrole oxide (SFO), 50 µg/ml, could most effectively induce EndoMT within 12 h. To understand the underlying molecular mechanism, we performed microarray, quantitative real-time PCR and western blot analysis to find key factors involved in SFO-induced EndoMT and demonstrated the involvement of the factors by RNAi. The expression of activating transcription factor 4 (ATF4), p75 neurotrophin receptor (p75NTR), and interleukin 8 (IL-8) was greatly increased in SFO-induced EndoMT. Knockdown of ATF4 inhibited the SFO-induced EndoMT completely, and knockdown of p75NTR or IL-8 partially inhibited the EndoMT, which suggests that all three factors were involved in the process. Furthermore, knockdown of p75NTR inhibited the SFO-increased IL-8 expression and secretion, and knockdown of ATF4 inhibited SFO-increased p75NTR level significantly. The ATF4/p75NTR/IL-8 signal pathway may have an important role in EndoMT induced by SFO. Our findings support potential novel targets for the therapeutics of cancer and fibrosis disease.

Role of A20 in cIAP-2 protection against tumor necrosis factor α (TNF-α)-mediated apoptosis in endothelial cells

Tumor necrosis factor α (TNF-α) influences endothelial cell viability by altering the regulatory molecules involved in induction or suppression of apoptosis. However, the underlying mechanisms are still not completely understood. In this study, we demonstrated that A20 (also known as TNFAIP3, tumor necrosis factor α-induced protein 3, and an anti-apoptotic protein) regulates the inhibitor of apoptosis protein-2 (cIAP-2) expression upon TNF-α induction in endothelial cells. Inhibition of A20 expression by its siRNA resulted in attenuating expression of TNF-α-induced cIAP-2, yet not cIAP-1 or XIAP. A20-induced cIAP-2 expression can be blocked by the inhibition of phosphatidyl inositol-3 kinase (PI3-K), but not nuclear factor (NF)-κB, while concomitantly increasing the number of endothelial apoptotic cells and caspase 3 activation. Moreover, TNF-α-mediated induction of apoptosis was enhanced by A20 inhibition, which could be rescued by cIAP-2. Taken together, these results identify A20 as a cytoprotective factor involved in cIAP-2 inhibitory pathway of TNF-α-induced apoptosis. This is consistent with the idea that endothelial cell viability is dependent on interactions between inducers and suppressors of apoptosis, susceptible to modulation by TNF-α.