6
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Knockdown of hypoxia-inducible factor 1-alpha (HIF1α) interferes with angiopoietin-like protein 2 (ANGPTL2) to attenuate high glucose-triggered hypoxia/reoxygenation injury in cardiomyocytes

      research-article
      a , a , a , b , a
      Bioengineered
      Taylor & Francis
      HIF1A, ANGPTL2, hypoxia/reoxygenation injury, cardiomyocytes

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          ABSTRACT

          To investigate the role of hypoxia-inducible factor 1-alpha (HIF1A) in hypoxia/reoxygenation (H/R) injury of cardiomyocytes induced by high glucose (HG). The in vitro model of coronary heart disease with diabetes was that H9c2 cells were stimulated by H/R and HG. Quantitative reverse transcription PCR (RT-qPCR) and Western blot analysis were used to detect the expression of HIF1A and angiopoietin-like protein 2 (ANGPTL2) in H9c2 cells. Cell viability and apoptosis were, respectively, estimated by Cell Counting Kit 8 (CCK-8) and TUNEL assays. Lactate dehydrogenase (LDH) activity, inflammation and oxidative stress were in turn detected by their commercial assay kits. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay were used to confirm the association between HIF1A and ANGPTL2 promoter. The expression of nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway-related proteins and apoptosis-related proteins were also detected by Western blot analysis. As a result, ANGPTL2 expression was upregulated in H9c2 cells induced by HG or/and H/R. ANGPTL2 positively modulated HIF1A expression in H9c2 cells. HG or/and H/R suppressed the cell viability and promoted apoptosis, inflammatory response and oxidative stress levels in H9c2 cells. However, the knockdown of ANGPTL2 could reverse the above phenomena in H/R-stimulated-H9c2 cells through activation of Nrf2/HO-1 pathway. HIF1A transcriptionally activated ANGPTL2 expression. The effect of knockdown of ANGPTL2 on H/R triggered-H9c2 cells was weakened by HIF1A overexpression. In conclusion, knockdown of HIF1A downregulated ANGPTL2 to alleviate H/R injury in HG-induced H9c2 cells by activating the Nrf2/HO-1 pathway.

          Related collections

          Most cited references63

          • Record: found
          • Abstract: found
          • Article: not found

          Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method.

          The two most commonly used methods to analyze data from real-time, quantitative PCR experiments are absolute quantification and relative quantification. Absolute quantification determines the input copy number, usually by relating the PCR signal to a standard curve. Relative quantification relates the PCR signal of the target transcript in a treatment group to that of another sample such as an untreated control. The 2(-Delta Delta C(T)) method is a convenient way to analyze the relative changes in gene expression from real-time quantitative PCR experiments. The purpose of this report is to present the derivation, assumptions, and applications of the 2(-Delta Delta C(T)) method. In addition, we present the derivation and applications of two variations of the 2(-Delta Delta C(T)) method that may be useful in the analysis of real-time, quantitative PCR data. Copyright 2001 Elsevier Science (USA).
            Bookmark
            • Record: found
            • Abstract: found
            • Article: found
            Is Open Access

            PD-L1 is a novel direct target of HIF-1α, and its blockade under hypoxia enhanced MDSC-mediated T cell activation

            Hypoxia is a common feature of solid tumors (Semenza, 2011). Hypoxic zones in tumors attract immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs; Corzo et al., 2010), tumor-associated macrophages (TAMs; Doedens et al., 2010; Imtiyaz et al., 2010), and regulatory T cells (T reg cells; Clambey et al., 2012). MDSCs are a heterogeneous group of relatively immature myeloid cells and several studies have described mechanisms of MDSC-mediated immune suppression (Gabrilovich et al., 2012). A large body of preclinical and clinical data indicates that antibody blockade of immune checkpoints can significantly enhance antitumor immunity (Pardoll, 2012; West et al., 2013). Recently, antibody-mediated blockade of preprogrammed death 1 (PD-1; Topalian et al., 2012) and its ligand, PD-L1 (Brahmer et al., 2012), was shown to result in durable tumor regression and prolonged stabilization of disease in patients with advanced cancers. PD-1, a cell surface glycoprotein with a structure similar to cytotoxic T lymphocyte antigen 4 (CTLA-4), belongs to the B7 family of co-stimulatory/co-inhibitory molecules and plays a key part in immune regulation (Greenwald et al., 2005). PD-1 has two known ligands, PD-L1 (B7-H1) and PD-L2 (B7-DC). Although hypoxia has been shown to regulate the function and differentiation of MDSCs (Corzo et al., 2010), several major questions remain unresolved. The influence of hypoxia on the regulation of immune checkpoint receptors (PD-1 and CTLA-4) and their respective ligands (PD-L1, PD-L2, CD80, and CD86) on MDSCs remains largely obscure. Furthermore, the potential contribution of these immune checkpoint receptors and their respective ligands on MDSC function under hypoxia is still unknown. In the present study, we showed that hypoxia via hypoxia-inducible factor-1α (HIF-1α) selectively up-regulated PD-L1 on MDSCs, but not other B7 family members, by binding directly to the HRE in the PD-L1 proximal promoter. Blockade of PD-L1 under hypoxia abrogated MDSC-mediated T cell suppression by modulating MDSCs cytokine production. RESULTS AND DISCUSSION Differential expression of PD-L1 on tumor-infiltrating MDSCs versus splenic MDSCs and selective up-regulation of PD-L1 in splenic MDSCs under hypoxic stress We first compared the level of expression of PD-L1 and PD-L2 between splenic MDSCs and tumor-infiltrating MDSCs from tumor-bearing mice. We found that the percentage of PD-L1+ cells was significantly higher on tumor-infiltrating MDSCs as compared with splenic MDSC in B16-F10, LLC (Fig. 1 A), CT26, and 4T1 (Fig. 1 B) tumor models. No significant difference was found in the percentage of PD-L2+ cells in splenic MDSCs as compared with tumor-infiltrating MDSCs in four tumor models tested (Fig. 1 C). We did not observe any significant difference in the expression levels of other members of the B7 family such as CD80, CD86, PD-1, and CTLA-4 on MDSCs from spleen and tumor (unpublished data). Youn et al. (2008) previously observed no significant differences in the percentage of PD-L1+ or CD80+ cells within the splenic MDSCs from tumor-bearing mice and immature myeloid cells from naive tumor-free mice. However, by comparing the expression of immune checkpoint inhibitors between splenic and tumor-infiltrating MDSCs, we showed that there is a differential expression of PD-L1 on tumor-infiltrating MDSCs. Figure 1. Tumor-infiltrating MDSCs differentially express PD-L1 as compared with splenic MDSCs, and hypoxia selectively up-regulates PD-L1 on splenic MDSCs in tumor-bearing mice. Surface expression level of PD-L1 and PD-L2 on Gr1+ CD11b+ cells (MDSCs) from (B16-F10 and LLC; A; CT26 and 4T1; B) in spleens (black dotted line histogram) and tumor (black line histogram) as compared with isotype control (gray-shaded histogram) was analyzed by flow cytometry. (C) Statistically significant differences (indicated by asterisks) between tumor-infiltrating MDSCs and splenic MDSCs are shown (*, P 20 fold for HRE-4), comparable to their binding to an established HRE in VEGF, LDHA, and Glut1 genes. To determine whether this HIF-1α site (HRE-4) was a transcriptionally active HRE, MSC-1 cells were co-transfected with pGL4-hRluc/SV40 vector and pGL3 EV, pGL3 HRE-4, or pGL3 HRE-4 MUT vectors (Fig. 3 M) and grown under normoxia or hypoxia. After 48 h, firefly and renilla luciferase activities were measured. As shown in Fig. 3 N, hypoxia significantly increased the luciferase activity of HRE-4 reporter by more than threefold as compared with normoxia. More interestingly, the luciferase activity of HRE-4 MUT was significantly decreased (>50%) as compared with HRE-4 under hypoxia (Fig. 3 N). The results presented in Figs. 3 (H–N) demonstrate that PD-L1 is a direct HIF-1α target gene in MSC-1 cells. Thus, we provide evidence here that HIF-1α is a major regulator of PD-L1 mRNA and protein expression, and that HIF-1α regulates the expression of PD-L1 by binding directly to the HRE-4 in the PD-L1 proximal promoter. Blocking PD-L1 decreases MDSC-mediated T cell suppression under hypoxia by down-regulating MDSC IL-6 and IL-10 To directly test the functional consequences of hypoxia-induced up-regulation of PD-L1 in MDSC-mediated T cell suppression, the expression of PD-L1 was blocked on ex vivo MDSCs by using anti–PD-L1 monoclonal antibody. Hypoxia increased the ability of MDSCs to suppress both specific and nonspecific stimuli-mediated T cell proliferation (Fig. 4, A and B). Interestingly, blockade of PD-L1 under hypoxia significantly abrogated the suppressive activity of MDSCs in response to both nonspecific stimuli (anti-CD3/CD28 antibody; Fig. 4 A) and specific stimuli (TRP-2(180–88) peptide; Fig. 4 B). Under hypoxia, MDSCs acquired the ability to inhibit T cell function (Fig. 4, C and D) by decreasing the percentage of IFN-γ+ CD8+ and CD4+ T cells; whereas the percentage of IFN-γ+ CD8+ (Fig. 4 C) and IFN-γ+ CD4+ T cells (Fig. 4 D) significantly increased after PD-L1 blockade under hypoxic conditions. Thus, the immune suppressive function of MDSCs enhanced under hypoxia was abrogated after blocking PD-L1, and hypoxic up-regulation of PD-L1 on MDSCs is involved in mediating the suppressive action of MDSCs, at least in part, as we were not able to completely restore T cell proliferation and function after PD-L1 blockade on MDSCs under hypoxia. Figure 4. Blockade of PD-L1 under hypoxia down-regulates MDSC IL-6 and IL-10 and enhances T cell proliferation and function. MDSCs isolated from spleens of B16-F10 tumor-bearing mice were pretreated for 30 min on ice with 5 µg/ml control antibody (IgG) or antibody against PD-L1 (PDL1 Block) and co-cultured with splenocytes under normoxia and hypoxia for 72 h. (A and B) Effect of MDSC on proliferation of splenocytes stimulated with (A) anti-CD3/CD28 coated beads or (B) TRP-2(180–88) peptide under the indicated conditions. Cell proliferation was measured in triplicates by [3H]thymidine incorporation and expressed as counts per minute (CPM). (C and D) MDSCs were cultured with splenocytes from B16-F10 mice stimulated with anti-CD3/CD28. Intracellular IFN-γ production was evaluated by flow cytometry by gating on (C) CD3+CD8+ IFN-γ+ and (D) CD3+CD4+ IFN-γ+ populations. Statistically significant differences (indicated by asterisks) are shown (**, P 95% as evaluated by FACS analysis. MDSC functional assays. For evaluation of T cell proliferation, splenocytes from B16-F10 mice were plated into U-bottom 96-well plates along with MDSCs at different ratios (50,000 MDSC:200,000 splenocytes/well). Plates were stimulated with either anti-CD3/CD28 beads (Miltenyi Biotec) or TRP-2 180–88 peptide for 72 h at 37°C. Co-cultures were pulsed with thymidine (1 µCi/well; Promega) for 16–18 h before harvesting, and [3H]thymidine uptake was counted using Packard’s TopCount NXT liquid scintillation counter and expressed as counts per minute (CPM). For assessment of T cell functions, MDSCs co-cultured with splenocytes from B16-F10 mice were stimulated with anti-CD3/CD28 beads. After 72 h, intracellular IFN-γ production was evaluated by flow cytometry by gating on CD3+CD8+ IFN-γ+ and CD3+CD4+ IFN-γ+ populations. MDSCs cytokine production (ELISA). MDSCs isolated from spleens of B16-F10 tumor-bearing mice were pretreated for 30 min on ice with 5 μg/ml control antibody (IgG) or Anti-Mouse PD-L1 (B7-H1) Functional Grade Purified antibody 5 µg/ml (clone MIH5; eBioscience; PDL1 Block) and cultured under normoxia and hypoxia for 72 h. Supernatants were collected and the secretion of IL-6, IL-10, and IL-12p70 (eBioscience) was determined by ELISA. ChIP assay. ChIP was performed with lysates prepared from MSC-1 by using SimpleChIP Enzymatic Chromatin IP kit (Cell Signaling Technology). SYBR Green RT-qPCR was performed using the primers detailed in Table S1. Arginase enzymatic activity and NO (nitric oxide) production. Arginase activity was measured in MDSC cell lysates, and for NO production, culture supernatants were mixed with Greiss reagent and nitrite concentrations were determined as described earlier (Youn et al., 2008). Luciferase reporter assay. A 653-bp section corresponding to mouse PD-L1 promoter containing HRE4 sequence was inserted into the NheI–XhoI sites of pGL3-Basic vector (Promega). Mutation of HRE4 was performed by site-directed mutagenesis and verified by sequencing. A 56-bp mouse PD-L1 gene sequence was inserted into the Bgl II site of pGL3-Promoter (Promega). MSC-1 cells were co-transfected with 0.2 µg of pGL4-hRluc/SV40 vector (which contains renilla luciferase sequences downstream of the SV40 promoter) and 1 µg of pGL3 empty vector, pGL3 HRE-4, or pGL3 HRE-4 MUT vectors in 6-well plates with Lipofectamine 2000 (Invitrogen) in OPTIMEM (Invitrogen) medium and grown under normoxia or hypoxia. After 48 h, firefly and Renilla luciferase activities were measured using the Dual-Luciferase Reporter assay (Promega) and the ratio of firefly/Renilla luciferase was determined. Statistics. Data were analyzed with GraphPad Prism. Student’s t test was used for single comparisons. Online supplemental material. Table S1 shows genomic oligonucleotide primers used for amplification of immunoprecipitated DNA samples from ChIP assays. Online supplemental material is available at http://www.jem.org/cgi/content/full/jem.20131916/DC1. Supplementary Material Supplemental Material
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction.

              Type 2 (non-insulin-dependent) diabetes is associated with a marked increase in the risk of coronary heart disease. It has been debated whether patients with diabetes who have not had myocardial infarctions should be treated as aggressively for cardiovascular risk factors as patients who have had myocardial infarctions. To address this issue, we compared the seven-year incidence of myocardial infarction (fatal and nonfatal) among 1373 nondiabetic subjects with the incidence among 1059 diabetic subjects, all from a Finnish population-based study. The seven-year incidence rates of myocardial infarction in nondiabetic subjects with and without prior myocardial infarction at base line were 18.8 percent and 3.5 percent, respectively (P<0.001). The seven-year incidence rates of myocardial infarction in diabetic subjects with and without prior myocardial infarction at base line were 45.0 percent and 20.2 percent, respectively (P<0.001). The hazard ratio for death from coronary heart disease for diabetic subjects without prior myocardial infarction as compared with nondiabetic subjects with prior myocardial infarction was not significantly different from 1.0 (hazard ratio, 1.4; 95 percent confidence interval, 0.7 to 2.6) after adjustment for age and sex, suggesting similar risks of infarction in the two groups. After further adjustment for total cholesterol, hypertension, and smoking, this hazard ratio remained close to 1.0 (hazard ratio, 1.2; 95 percent confidence interval, 0.6 to 2.4). Our data suggest that diabetic patients without previous myocardial infarction have as high a risk of myocardial infarction as nondiabetic patients with previous myocardial infarction. These data provide a rationale for treating cardiovascular risk factors in diabetic patients as aggressively as in nondiabetic patients with prior myocardial infarction.
                Bookmark

                Author and article information

                Journal
                Bioengineered
                Bioengineered
                Bioengineered
                Taylor & Francis
                2165-5979
                2165-5987
                3 January 2022
                2022
                3 January 2022
                : 13
                : 1
                : 1476-1490
                Affiliations
                [a ]Department of Cardiology, The Second Affiliated Hospital of Xi’an Medical University; , Xi’an, P.R. China
                [b ]Experimental Center, The Second Affiliated Hospital of Xi’an Medical University; , Xi’an, P.R. China
                Author notes
                CONTACT Meng Liang liangmeng102@ 123456126.com Department of Cardiology, The Second Affiliated Hospital of Xi’an Medical University; , 167 Fangdong Street, Textile City, Baqiao District, Xi’an, Shaanxi 710038, P.R. China
                Article
                2019874
                10.1080/21655979.2021.2019874
                8805963
                34974813
                7347265b-bd2b-48a5-a279-ababd9d05eb5
                © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                Page count
                Figures: 8, References: 63, Pages: 15
                Categories
                Research Article
                Research Paper

                Biomedical engineering
                hif1a,angptl2,hypoxia/reoxygenation injury,cardiomyocytes
                Biomedical engineering
                hif1a, angptl2, hypoxia/reoxygenation injury, cardiomyocytes

                Comments

                Comment on this article