Trimethylamine N-oxide aggravates vascular permeability and endothelial cell dysfunction under diabetic condition: in vitro and in vivo study.

AIM: To provide the direct evidence for the crucial role of trimethylamine N-oxide (TMAO) in vascular permeability and endothelial cell dysfunction under diabetic condition. METHODS: The role of TMAO on the in vitro biological effect of human retinal microvascular endothelial cells (HRMEC) under high glucose conditions was tested by a cell counting kit, wound healing, a transwell and a tube formation assay. The inflammation-related gene expression affected by TMAO was tested by real-time polymerase chain reaction (RT-PCR). The expression of the cell junction was measured by Western blotting (WB) and immunofluorescence staining. In addition, two groups of rat models, diabetic and non-diabetic, were fed with normal or 0.1% TMAO for 16wk, and their plasma levels of TMAO, vascular endothelial growth factor (VEGF), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were tested. The vascular permeability of rat retinas was measured using FITC-Dextran, and the expression of zonula occludens (ZO)-1 and claudin-5 in rat retinas was detected by WB or immunofluorescence staining. RESULTS: TMAO administration significantly increased the cell proliferation, migration, and tube formation of primary HRMEC either in normal or high-glucose conditions. RT-PCR showed elevated inflammation-related gene expression of HRMEC under TMAO stimulation, while WB or immunofluorescence staining indicated decreased cell junction ZO-1 and occludin expression after high-glucose and TMAO treatment. Diabetic rats showed higher plasma levels of TMAO as well as retinal vascular leakage, which were even higher in TMAO-feeding diabetic rats. Furthermore, TMAO administration increased the rat plasma levels of VEGF, IL-6 and TNF-α while decreasing the retinal expression levels of ZO-1 and claudin-5. CONCLUSION: TMAO enhances the proliferation, migration, and tube formation of HRMEC, as well as destroys their vascular integrity and tight connection. It also regulates the expression of VEGF, IL-6, and TNF-α.

Proteomic analysis of anti-angiogenic effects by conbercept in the mice with oxygen induced retinopathy.

AIM: To analyze the retinal proteomes with and without conbercept treatments in mice with oxygen-induced retinopathy (OIR) and identify proteins involved in the molecular mechanisms mediated by conbercept. METHODS: OIR was induced in fifty-six C57BL/6J mouse pups and randomly divided into four groups. Group 1: Normal17 (n=7), mice without OIR and treated with normal air. Group 2: OIR12/EXP1 (n=14), mice received 75% oxygen from postnatal day (P) 7 to 12. Group 3: OIR17/Control (n=14), mice received 75% oxygen from P7 to P12 and then normal air to P17. Group 4: Lang17/EXP2 (n=21), mice received 75% oxygen from P7 to P12 with intravitreal injection of 1 µL conbercept at the concentration of 10 mg/mL at P12, and then normal air from P12 to P17. Liquid Chromatography-Mass Spectrometry (LC-MS)/MS data were reviewed to find proteins that were up-regulated after the conbercept treatment. Gene ontology (GO) analysis was performed of conbercept-mediated changes in proteins involved in single-organism processes, biological regulation, cellular processes, immune responses, metabolic processes, locomotion and multiple-organism processes. RESULTS: Conbercept induced a reversal of hypoxia-inducible factor 1 signaling pathway as revealed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and also induced down-regulation of proteins involved in blood coagulation and fibrin clot formation as demonstrated by the Database for Annotation, Visualization and Integrated Discovery (DAVID) and the stimulation of interferon genes studies. These appear to be risk factors of retinal fibrosis. Additional conbercept-specific fibrosis risk factors were also identified and may serve as therapeutic targets for fibrosis. CONCLUSION: Our studies reveal that many novel proteins are differentially regulated by conbercept. The new insights may warrant a valuable resource for conbercept treatment.

Blockade of insulin receptor substrate-1 inhibits biological behavior of choroidal endothelial cells.

AIM: To investigate the effects of blockade of insulin receptor substrate-1 (IRS-1) on the bio-function of tube formation of human choroidal endothelial cells (HCECs). METHODS: Quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were performed to determine the expression level of IRS-1 and phospho-IRS-1 in HCECs. Tube formation of HCECs was analyzed using three dimensional in vitro Matrigel assay with or without IRS-1 blockage via IRS-1 inhibitor (GS-101) and vascular endothelial growth factor receptor 2 (VEGFR2) inhibitor. In addition, cell counting kit (CCK)-8 and Transwell migration assay were exerted to analyze the effects of blockade of IRS-1 on the bio-function of proliferation and migration of HCECs, respectively. The apoptosis of HCECs was examined using flow cytometry (FCM). RESULTS: RT-PCR and Western blot revealed that IRS-1 phospho-IRS-1 were expressed in HCECs and the expression level was enhanced by stimulation of VEGF-A. The number of tube formation was decreased significantly in GS-101 treated groups compared to phosphate buffered saline (PBS) treated control groups. Furthermore, both cell proliferation and migration of HCECs were decreased in the presence of GS-101. FCM analysis showed that the apoptosis of HCECs was enhanced when the cells were treated with GS-101. Western blot also showed that the expression level of cleaved-caspase 3 in GS-101 treated group was higher than that in control group. CONCLUSION: Blockade of IRS-1 can inhibit tube formation of HCECs through reducing cell proliferation and migration and promoting cell apoptosis.

High glucose: activating autophagy and affecting the biological behavior of human lens epithelial cells.

AIM: To clarify the effect of autophagy on human lens epithelial cells (HLECs) under high glucose conditions. METHODS: HLECs were cultured with different concentrations of glucose and 3-methyladenine (3-MA); the expression of autophagy-related protein LC3B was detected by Western blotting and immunofluorescence histochemistry. The migration of HLECs was quantified by scratch wound assay and the expression of transforming growth factor-ß (TGF-ß) was measured by real-time polymerase chain reaction. RESULTS: Compared with 5 mmol/L normal glucose treatment, 40 mmol/L glucose treatment can significantly increase the generation of autophagosome in HLECs, which could be inhibited by 0.375 mmol/L 3-MA treatment. The migration of HLECs and the expression of TGF-ß in HLECs induced by high glucose were significantly suppressed by 0.375 mmol/L 3-MA treatment. CONCLUSION: Autophagy promotes HLECs cell migration and increases the expression of TGF-ß after exposed to high glucose, which may relate to the development of diabetic cataract.

Monocyte chemoattractant protein 1 and fractalkine play opposite roles in angiogenesis via recruitment of different macrophage subtypes.

AIM: To explore the interaction between macrophages and chemokines [monocyte chemoattractant protein 1 (MCP-1/CCL2) and fractalkine/CX3CL1] and the effects of their interaction on neovascularization. METHODS: Human peripheral blood mononuclear cells, donated by healthy volunteers, were separated and cultured in RPMI-1640 medium containing 10% fetal bovine serum, then induced into macrophages by stimulation with 30 µg/L granulocyte macrophage-colony stimulating factor (GM-CSF). The expression of CCR2 and/or CX3CR1 in the macrophages was examined using flow cytometry. Macrophages were then stimulated with recombinant human CCL2 (rh-CCL2) or recombinant human CX3CL1 (rh-CX3CL1). The expression of angiogenesis-related genes, including VEGF-A, THBS-1 and ADAMTS-1 were examined using real-time quantitative polymerase chain reaction (PCR). Supernatants from stimulated macrophages were used in an assay of human retinal endothelial cell (HREC) proliferation. Finally, stimulated macrophages were co-cultured with HREC in a migration assay. RESULTS: The expression rate of CCR2 in macrophages stimulated by GM-CSF was 42%±1.9%. The expression rate of CX3CR1 was 71%±3.3%. Compared with vehicle-treated groups, gene expression of VEGF-A in the macrophages was greater in 150 mg/L CCL2-treated groups (P<0.05), while expression of THBS-1 and ADAMTS-1 was significantly lower (P<0.05). By contrast, compared with vehicle-treated groups, expression of VEGF-A in 150 mg/L CX3CL1-treated groups was significantly lower (P<0.05), while expression of THBS-1 and ADAMTS-1 was greater (P<0.05). Supernatants from CCL2 treated macrophages promoted proliferation of HREC (P<0.05), while supernatants from CX3CL1-treated macrophages inhibited the proliferation of HREC (P<0.05). HREC migration increased when co-cultured with CCL2-treated macrophages, but decreased with CX3CL1-treated macrophages (P<0.05). CONCLUSION: CCL2 and CX3CL1 exert different effects in regulation of macrophage in expression of angiogenesis-related factors, including VEGF-A, THBS-1 and ADAMTS-1. Our findings suggest that CCL2 and CX3CL1 may be candidate proteins for further exploration of novel targets for treatment of ocular neovascularization.

Role of IL-17 in LPS-induced acute lung injury: an in vivo study.

To assess the clinical significance of IL-17 in patients with sepsis-induced acute respiratory distress syndrome (ARDS) and to investigate the effects of IL-17 blocking in a mouse model of acute lung injury (ALI). Significantly increased IL-17 level was found in patients with sepsis-related ARDS compared to healthy controls, whereas significantly increased plasma IL-17 level was also observed in non-survivors compared to that in survivors. According to the data from the mouse ALI model, we found significantly increased IL-17 level in lung tissue lysates, mouse bronchoalveolar lavage fluid (mBALF) and plasma at 6, 12 and 24 h after ALI. Histological analyses revealed that reduced sign of pathological changes and lung injury score in the lungs at 48 h after IL-17 blocking antibody administration. Reduced level of proinflammatory tumor necrosis factor α and increased level of anti-inflammatory factor interleukin-10 were found in both mBALF and plasma. Moreover, IL-17 blocking antibody administration attenuated the expression of RORγt and activity of PI3K-Akt pathway. Increased IL-17 was presented in patients with sepsis-induced ARDS and IL-17 may serve as a biomarker to indicate the severity of ARDS. Moreover, IL-17 antibody administration could relieve the ALI symptom by affecting RORγt level and PI3K pathway.

Anti-apoptosis effects of vascular endothelial cadherin in experimental corneal neovascularization.

AIM: To explore the effects and mechanism of vascular endothelial cadherin (VE-cadherin) on experimental corneal neovascularization (CRNV). METHODS: Mouse corneas were burned with sodium hydroxide to build a CRNV model. The burned corneas were locally administrated with anti-mouse VE-cadherin neutralizing antibody. Annexin V and cluster of differentiation 31 (CD31) double staining was used to measure vascular endothelial cell apoptosis with the use of flow cytometry (FCM). The protein expression of NADPH oxidase 2 (Nox2), caspase-3, and protein kinase C (PKC) in the burned corneas were examined by Western blot. Human retinal endothelial cell (HREC) proliferation was detected using a Cell Counting Kit 8 (CCK-8) assay in vitro. RESULTS: The amount of CRNV peaked two weeks after the alkali burn. FCM confirmed that VE-cadherin neutralizing antibody treatment increased CD31 positive cell apoptosis. Western blot revealed that the intracorneal protein expression of Nox2 and caspase-3 were up-regulated, while PKC was down-regulated in the VE-cadherin neutralizing antibody administrated group. CCK-8 assay showed that VE-cadherin neutralizing antibody markedly inhibited HREC proliferation. CONCLUSION: VE-cadherin exhibited an anti-apoptosis effect through enhanced PKC signaling and an enhanced cell proliferation pathway.

Electrostatic nucleic acid nanoassembly enables hybridization chain reaction in living cells for ultrasensitive mRNA imaging.

Efficient approaches for intracellular delivery of nucleic acid reagents to achieve sensitive detection and regulation of gene and protein expressions are essential for chemistry and biology. We develop a novel electrostatic DNA nanoassembly that, for the first time, realizes hybridization chain reaction (HCR), a target-initiated alternating hybridization reaction between two hairpin probes, for signal amplification in living cells. The DNA nanoassembly has a designed structure with a core gold nanoparticle, a cationic peptide interlayer, and an electrostatically assembled outer layer of fluorophore-labeled hairpin DNA probes. It is shown to have high efficiency for cellular delivery of DNA probes via a unique endocytosis-independent mechanism that confers a significant advantage of overcoming endosomal entrapment. Moreover, electrostatic assembly of DNA probes enables target-initialized release of the probes from the nanoassembly via HCR. This intracellular HCR offers efficient signal amplification and enables ultrasensitive fluorescence activation imaging of mRNA expression with a picomolar detection limit. The results imply that the developed nanoassembly may provide an invaluable platform in low-abundance biomarker discovery and regulation for cell biology and theranostics.

The upregulated expression of OX40/OX40L and their promotion of T cells proliferation in the murine model of asthma.

OBJECTIVE: To investigate whether the expression of OX40/OX40 ligand (OX40L) was upregulated in a murine model of asthma and their significance in the pathogenesis of asthma. METHODS: After an ovalbumin-sensitized/challenged murine model of asthma was established, the expressions of OX40, OX40L in peripheral blood mononuclear cells (PBMCs) and bronchoalveolar lavage fluid (BALF) cell pellets were measured. Then T cell proliferation was analyzed by cell counting kit-8 (CCK8), and the protein levels of OX40 and OX40L in the lungs were determined by immunohistochemistry. The concentrations of IL-4 and IFN-γ in BALF and T cell culture supernatant were evaluated by ELISA. RESULTS: The percentages of CD4(+)OX40(+), CD19(+)OX40L(+), F4/80(+)OX40L(+) in PBMCs and BALF cell pellets were higher in asthma group than in control group (all P<0.01). The proliferation capacity of T cells in asthma group was higher than that in control group (P<0.05). In asthma group, stimulation of OX40 by anti-OX40 mAb obviously promoted T cell proliferation and secretion of IL-4 and IFN-γ. Immunohistochemistry assay showed that OX40 and OX40L protein levels were higher in asthma group than those in control group (all P<0.05). CONCLUSIONS: The expressions of OX40 and OX40L were upregulated in the murine asthmatic model. The upregulation of OX40/OX40L signals could induce the proliferation and cytokines secretion of T cells in asthmatic mice, indicating that OX40/OX40L signal was involved in the pathogenesis of asthma.

Inhibitory effect of CCR3 signal on alkali-induced corneal neovascularization.

AIM: To investigate the effect of CC chemokine receptor 3 (CCR3) signal on corneal neovascularization (CRNV) induced by alkali burn and to explore its mechanism. METHODS: Specific pathogen-free male BALB/C mice (aged 6-8 weeks) were randomly divided into CCR3-antagonist treated group (experimental group) and control group. CRNV was induced by alkali burn in mice. The time kinetic CCR3 expression in injured corneas was examined by reverse transcription polymerase chain reaction (RT-PCR). CCR3-antagonist (SB-328437 at different concentration of 125µg/mL, 250µg/mL, and 500µg/mL) was locally administrated after alkali injury. The formation of CRNV was assessed by CD31 corneal whole mount staining at two weeks after injury. Monocyte chemotactic protein 1 (MCP-1), monocyte chemotactic protein 3 (MCP-3) expressions in the early phase after injury were quantified and compared by RT-PCR. Macrophage intracorneal accumulation in the early phase after injury was evaluated and compared by immunohistochemistry. RESULTS: Alkali injury induced the time kinetic intracorneal CCR3 expression. 500µg/mL of CCR3-antagonist treatment in the early phase but not the late phase resulted in significant impaired CRNV as compared to control group (P<0.05). CCR3-antagonist treatment in the early phase significantly reduced the intracorneal MCP-1 and MCP-3 enhancement compare to control group at day 2 and day 4 (P<0.05). Moreover, the number of intracorneal macrophage infiltration in the experimental group was reduced than those in control group at day 4 (P<0.05). CONCLUSION: CCR3 signal is involved in alkali-induced CRNV. CCR3-antagonist can inhibit alkali-induced CRNV by reducing the intracorneal MCP-1 and MCP-3 mRNA expression and the intracorneal macrophage infiltration.

Inhibited experimental corneal neovascularization by neutralizing anti-SDF-1α antibody.

AIM: To explore the effect of SDF-1α on the development of experimental corneal neovascularization (CRNV). METHODS: CRNV was induced by alkali injury in mice. The expression of SDF-1α and CXCR4 in burned corneas was examined by Flow Cytometry. Neutralizing anti-mouse SDF-1α antibody was locally administrated after alkali injury and the formation of CRNV 2 weeks after injury was assessed by Immunohistochemistry. The expression of VEGF and C-Kit in burned corneas was detected by RT-PCR. RESULTS: The number of CRNV peaks at 2 weeks after alkali injury. Compared to control group, SDF-1α neutralizing antibody treatment significantly decreased the number of CRNV. RT-PCR confirmed that SDF-1α neutralizing antibody treatment resulted in decreased intracorneal VEGF and C-Kit expression. CONCLUSION: SDF-1α neutralizing antibody treated mice exhibited impaired experimental CRNV through down regulated VEGF and C-Kit expression.

[Eukaryotic expression and biological activity of recombinant human IL-17B protein].

AIM: To construct pCEP4/hIL-17B recombinant expression vector and express it stably in eukaryotic cells and investigate the biological activity in vitro. METHODS: The CDS region of human IL-17B gene was cloned by RT-PCR. After identification by sequencing, the hIL-17B gene was inserted into expression vector of pCEP4 to construct the recombinant vector pCEP4/hIL-17B, then transfected into 293T cells. The transgenic 293T cell line stably expressing rhIL-17B protein was selected in the presence of Hygromycin B. After FCS-free cultivation and sub-cloning, The IL-17B/mFc gene and protein expression was confirmed by RT-PCR, ELISA and Western blot analysis. To investigate the ability of combination with IL-17B receptor on human leukemic monocytic cell line, THP-1, by Flow cytometrical analysis (FACS) and of stimulation to secret cytokines in vitro. RESULTS: The recombinant pCEP4/hIL-17B and its transgenic 293T cells stably expressing rhIL-17B protein were obtained successfully. FACS analysis showed its high affinity with its receptor and it can stimulated THP-1 cell line to excrete IL-1ß and TNF-α in vitro and consistently caused a dose-dependent influx of neutrophil into the peritoneal cavity by intraperitoneal injection in vivo. CONCLUSION: The obtainment of transgenic 293T cell line stably expressing rhIL-17B protein paved the way for further study on biological functions of hIL-17B.

[Prokaryotic expression and biological activity of recombinant human IL-17F/His protein].

AIM: To Prepare recombinant human IL-17F/His protein and investigate its biological activity in vitro. METHODS: The gene region of human IL-17F was cloned by RT-PCR. After identification by sequencing, the hIL-17F gene encoding function domain was cloned into expression plasmid PQE3.0 and transfected into E.coli M15. By the induction of Isopropyl-ß-D-Thiogalacto-Pyranoside(IPTG), recombinant IL-17F/His protein was effectively expressed in E.coli M15. The recombinant protein was identified by Western blot. RESULTS: After renaturation and purification by HiTrap(TM); affinity column, the recombinant protein can up-regulate macrophages to secret TNF-α, IL-6 and other relative cytokines. It also promoted proliferation of HeLa cells in vitro. CONCLUSION: hIL-17F/His recombinant protein is of high biological activity, which can be used to make further study of its special characteristic.

Potential involvement of nitric oxide synthase but not inducible nitric oxide synthase in the development of experimental corneal neovascularization.

AIM: To investigate the effect of nitric oxide and its synthetase on experimental corneal neovascularization (CRNV). METHODS: CRNV was induced by alkali injury in mice, nitric oxide synthetase (NOS) was inhibited by NG-nitro-L-arginine (L-NAME) and inducible nitric oxide synthetase (iNOS) was inhibited by aminoguanidine hemisulfate salt (AG). The inhibitory effect was detected at day 2 and 4 after corneal alkali injury by reverse transcription polymerase chain reaction (RT-PCR). CRNV was compared between the control and the treated mice by microscopic observation and corneal whole mount CD31 immunostaining. RESULTS: The inhibition of L-NAME to NOS and AG to iNOS after corneal injury was confirmed by RT-PCR (P<0.05). Compared with control mice, L-NAME treated mice exhibited significantly decreased CRNV areas (P<0.05). In contrast, AG treatment failed to attenuate alkali induced CRNV (P>0.05). CONCLUSION: Our findings suggest that NOS but not iNOS plays a critical role in alkali injury induced CRNV.

[Prokaryotic expression, purification and biological activity of recombinant human IL-17/His protein].

AIM: To investigate the biological activity of recombinant human IL-17 protein in vitro. METHODS: The gene region of human IL-17 was cloned by RT-PCR. After identification by sequencing, the hIL-17 gene encoding function domain was cloned into expression plasmid PQE3.0 and transfect into E.coli M15. By the induction of Isopropyl-beta-D-Thiogalacto-Pyranoside (IPTG), recombinant IL-17/His protein was effectively expressed in E.coli M15. The recombinant protein was identified by Western blot. RESULTS: After denaturation, renaturation and purification by HiTrap affinity column, the recombinant protein stimulated HeLa, a human uterine cervix cancer cell line, to excrete IL-6 and GM-CSF in vitro. CONCLUSION: IL-17/His recombinant protein is of high biological activity, which can be used to make further study of auto-immune diseases.

[Preparation and characterization of two novel functional monoclonal antibodies against human OX40L].

AIM: To prepare novel anti-OX40L functional monoclonal antibodies and characterize their distinct biological functions. METHODS: Routine immunization of BALB/c mice by a tansfected cell line L929/OX40L expressing high level of OX40L as antigens. Then fuse the immunized spleen with Sp2/0, a kind of myloma, and screen the positive clones by FCS with L929/OX40L as a positive control.After acquisition of the hybidomas secreting anti-OX40L mAb, investigation of their biological activities by Western blot, rapid isotyping analysis, karyotype analysis, competitive inhibition test, indirect immunofluorescence and MTT incorporation assay were followed. RESULTS: Obtain two stable hybridomas, 4D6 and 5C2, which could continuously secret specific anti-OX40L monoclonal antibodies. The following biological activity studies showed that these monoclonal antibodies could both recognize the natural OX40L expressed on the mature DC, especially the OX40L on the several leukemia cell lines, such as Jurkat, SHI-1, U937 etc. Furthermore, they could also suppress the proliferation of SHI-1 in vitro. CONCLUSION: Two hybridomas secreting anti-OX40L monoclonal antibodies continuously and steadily have been established. These monoclonal antibodies could specifically recognize human OX40L and effect the proliferation of leukemia cell line SHI-1 through OX40/OX40L costimulatory signals.