Increased angiopoietin-like 4 expression ameliorates inflammatory bowel diseases via suppressing CD8+ T cell activities

Inflammatory bowel disease (IBD) involves infiltration of leukocytes into intestinal tissue, resulting in intestinal damage induced by reactive oxygen species (ROS). Pro-inflammatory cytokines and cell adhesion molecules (CAMs) play important roles in this infiltration of leukocytes. The roles of heat shock factor 1 (HSF1) and heat shock proteins (HSPs) in the development of IBD are unclear. In this study, we examined the roles of HSF1 and HSPs in an animal model of IBD, dextran sulfate sodium (DSS)-induced colitis. The colitis worsened or was ameliorated in HSF1-null mice or transgenic mice expressing HSP70 (or HSF1), respectively. Administration of DSS up-regulated the expression of HSP70 in colonic tissues in an HSF1-dependent manner. Expression of pro-inflammatory cytokines and CAMs and the level of cell death observed in colonic tissues were increased or decreased in DSS-treated HSF1-null mice or transgenic mice expressing HSP70, respectively, relative to control wild-type mice. Relative to macrophages from control wild-type mice, macrophages prepared from HSF1-null mice or transgenic mice expressing HSP70 displayed enhanced or reduced activity, respectively, for the generation of pro-inflammatory cytokines in response to lipopolysaccharide stimulation. Suppression of HSF1 or HSP70 expression in vitro stimulated lipopolysaccharide-induced up-regulation of CAMs or ROS-induced cell death, respectively. This study provides the first genetic evidence that HSF1 and HSP70 play a role in protecting against DSS-induced colitis. Furthermore, this protective role seems to involve various mechanisms, such as suppression of expression of pro-inflammatory cytokines and CAMs and ROS-induced cell death.

Positive Role of CCAAT/Enhancer-Binding Protein Homologous Protein, a Transcription Factor Involved in the Endoplasmic Reticulum Stress Response in the Development of Colitis

Hypoxia and the hypoxia-inducible factor (HIF) transcription factor regulate angiogenic-osteogenic coupling and osteoclast-mediated bone resorption. To determine how HIF might coordinate osteoclast and osteoblast function, we studied angiopoietin-like 4 (ANGPTL4), the top HIF target gene in an Illumina HumanWG-6 v3.0 48k array of normoxic vs. hypoxic osteoclasts differentiated from human CD14+ monocytes (14.3-fold induction, P<0.0004). ANGPTL4 mRNA and protein were induced by 24 h at 2% O2 in human primary osteoclasts, monocytes, and osteoblasts. ANGPTL4 protein was observed by immunofluorescence in osteoclasts and osteoblasts in vivo. Normoxic inducers of HIF (CoCl2, desferrioxamine, and l-mimosine) and 100 ng/ml ANGPTL4 stimulated osteoclastic resorption 2- to 3-fold in assays of lacunar dentine resorption, without affecting osteoclast viability. Isoform-specific HIF-1α small interfering RNA ablated hypoxic induction of ANGPTL4 and of resorption, which was rescued by addition of exogenous ANGPTL4 (P<0.001). In the osteoblastic Saos2 cell line, ANGPTL4 caused a dose-dependent increase in proliferation (P<0.01, 100 ng/ml) and, at lower doses (1–25 ng/ml), mineralization. These results demonstrate that HIF is sufficient to enhance osteoclast-mediated bone resorption and that ANGPTL4 can compensate for HIF-1α deficiency with respect to stimulation of osteoclast activity and also augments osteoblast proliferation and differentiation.—Knowles, H. J., Cleton-Jansen, A.-M., Korsching, E., and Athanasou, N.A. Hypoxia-inducible factor regulates osteoclast-mediated bone resorption: role of angiopoietin-like 4.

Hypoxia and the hypoxia‐inducible factor (HIF) transcription factor regulate angiogenic‐os‐teogenic coupling and osteoclast‐mediated bone resorption. To determine how HIF might coordinate osteoclast and osteoblast function, we studied angiopoi‐etin‐like 4 (ANGPTL4), the top HIF target gene in an Illumina HumanWG‐6 v3.0 48k array of normoxic vs. hypoxic osteoclasts differentiated from human CD14 + monocytes (14.3‐fold induction, P&lt;0.0004). ANGPTL4 mRNA and protein were induced by 24 h at 2% O 2 in human primary osteoclasts, monocytes, and osteo‐blasts. ANGPTL4 protein was observed by immunofluorescence in osteoclasts and osteoblasts in vivo. Nor‐moxic inducers of HIF (CoCl 2 , desferrioxamine, and l ‐mimosine) and 100 ng/ml ANGPTL4 stimulated os‐teoclastic resorption 2‐ to 3‐fold in assays of lacunar dentine resorption, without affecting osteoclast viability. Isoform‐specific HIF‐1α small interfering RNA ablated hypoxic induction of ANGPTL4 and of resorption, which was rescued by addition of exogenous ANGPTL4 ( P&gt; 0.001). In the osteoblastic Saos2 cell line, ANGPTL4 caused a dose‐dependent increase in proliferation ( P &lt;0.01, 100 ng/ml) and, at lower doses (1–25 ng/ml), mineralization. These results demonstrate that HIF is sufficient to enhance osteoclast‐mediated bone resorption and that ANGPTL4 can compensate for HIF‐1α deficiency with respect to stimulation of osteoclast activity and also augments osteoblast proliferation and differentiation.—Knowles, H. J., Cleton‐Jansen, A.‐M., Korsching, E., and Athanasou, N.A. Hypoxia‐inducible factor regulates osteoclast‐mediated bone resorption: role of angiopoietin‐like 4. FASEB J. 24, 4648–4659 (2010). www.fasebj.org

Transitional cell carcinoma is the most common urothelial cancer in the US. Current therapeutic options have been unable to overcome issues with the highly recurrent nature of this tumor, which requires frequent follow-up making urinary bladder cancer, one of the most expensive solid tumors to manage. Microarray-based gene expression analysis in response to capsaicin treatment identified significant upregulation of angiopoietin-like 4 (ANGPTL4) compared with solvent-treated bladder cancer cells. The focus of this study was to determine the functional relevance of ANGPTL4 in normal urothelial and bladder cancer cells. The microarray data was validated in a panel of normal, immortalized and bladder cancer cells of increasing stage by real-time qPCR, immunoblotting, and ELISA. To determine the possible function of ANGPTL4, we knocked down and overexpressed ANGPTL4 in normal urothelial and bladder cancer cells respectively. The role of ANGPTL4 in growth, proliferation and angiogenesis was assessed. Our results show that normal urothelial cells have significantly higher levels of ANGPTL4 when compared to non-tumorigenic and bladder cancer cells. Upon capsaicin treatment ANGPTL4 levels increased in all cell lines tested. Overexpression of ANGPTL4 in the metastatic cell line TCCSUP, led to decrease in cell growth. Further, ANGPTL4 knockdown increased cell growth in the normal urothelial cell line. Capsaicin treatment decreased the expression of VEGF in bladder cancer cell lines UMUC-3 and T24 as well as reduced expression in normal urothelium, albeit initial results in ANGPLT4-knockdown in normal urothelium indicates no change in VEGF expression. Our results thus far suggest that the loss of ANGPTL4 expression may be involved in bladder cancer. The mechanism involved is under investigation. Capsaicin remains an attractive compound for further studies in bladder cancer. Supported by RO3 CA136058 (RG) and NIHT32 T32CA148724 (EC). Citation Format: Eduardo Cardenas, Tiffani Horton, Rita Ghosh. The functional relevance of decreased ANGPTL4 in human urinary bladder cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 389. doi:10.1158/1538-7445.AM2013-389

BackgroundLipid metabolism related factors, such as angiopoietin‐like protein 3 (ANGPTL3), angiopoietin‐like 4 (ANGPTL4), fatty acid‐binding protein 4 (FABP4) are newly discovered factors that can affect coronary artery disease (CAD). In this study, we aimed to investigate the relationship between CAD and these lipid metabolism factors.HypothesisANGPTL3, ANGPTL4, and FABP4 may provide a new method for the control of CAD risk factors and the prevention and treatment of CAD.MethodsWe enrolled 284 consecutive inpatients with suspected CAD and divided them into CAD and non‐CAD groups based on the coronary angiography results. Serum ANGPTL3, ANGPTL4, FABP4, and tumor necrosis factor‐α (TNF‐α) levels were estimated using the enzyme‐linked immunosorbent assay. Multivariate logistic regression was used to assess the risk factors for CAD. The receiver operating characteristic curve was used to determine the cutoff and diagnostic values.ResultsThe serum TNF‐α, FABP4, ANGPTL3, and ANGPTL4 values showed a significant difference between the CAD and non‐CAD groups (p < .05). After adjusting for confounding factors, the FABP4, ANGPTL3, and ANGPTL4 levels were independently associated with CAD (p < .05). The ANGPTL3 expression level was an independent risk factor for CAD in patients with hypertension, but not in those without hypertension. The ANGPTL3 > 67.53 ng/mL, ANGPTL4 > 29.95 ng/mL, and FABP4 > 1421.25 ng/L combination had the highest diagnostic value for CAD.ConclusionANGPTL3, ANGPTL4, and FABP4 were identified as independent risk factors for CAD and have valuable clinical implications for the diagnosis and treatment of CAD.

Regulation of angiopoietin-like 4 and lipoprotein lipase in human adipose tissue

Beyond Gene Discovery in Inflammatory Bowel Disease: The Emerging Role of Epigenetics

Many gastrointestinal diseases exhibit a protracted and aggravated inflammatory response that can lead to hypercytokinaemia, culminating in extensive tissue damage. Recently, angiopoietin-like 4 (ANGPTL4) has been implicated in many inflammation-associated diseases. However, how ANGPTL4 regulates colonic inflammation remains unclear. Herein, we show that ANGPTL4 deficiency in mice (ANGPTL4−/−) exacerbated colonic inflammation induced by dextran sulfate sodium (DSS) or stearic acid. Microbiota was similar between the two genotypes prior DSS challenge. A microarray gene expression profile of the colon from DSS-treated ANGPTL4−/− mice was enriched for genes involved in leukocyte migration and infiltration, and showed a close association to inflamed ulcerative colitis (UC), whereas the profile from ANGPTL4+/+ littermates resembled that of non-inflamed UC biopsies. Bone marrow transplantation demonstrates the intrinsic role of colonic ANGPTL4 in regulating leukocyte infiltration during DSS-induced inflammation. Using immortalized human colon epithelial cells, we revealed that the ANGPTL4-mediated upregulation of tristetraprolin expression operates through CREB and NF-κB transcription factors, which in turn, regulates the stability of chemokines. Together, our findings suggest that ANGPTL4 protects against acute colonic inflammation and that its absence exacerbates the severity of inflammation. Our findings emphasize the importance of ANGPTL4 as a novel target for therapy in regulating and attenuating inflammation.

HDL-apoA-I induces the expression of angiopoietin like 4 (ANGPTL4) in endothelial cells via a PI3K/AKT/FOXO1 signaling pathway

ObjectiveANGPTL7 is a member of the Angiopoietin-like (ANGPTL) protein family that is composed of eight proteins (1–8). Increasing evidence is associating ANGPTL proteins to obesity and insulin resistance. The biological role of ANGPTL7 is yet to be understood except for a recently proposed role in the pathophysiology of glaucoma. This study was designed to shed light on the function of ANGPTL7 in obesity and its modulation by physical exercise as well as its potential association with lipid profile.MethodsA total of 144 subjects were enrolled in this study and finished three months of physical exercise. The participants were classified based on their BMI, 82 subjects were non-obese and 62 obese. ANGPTL7 levels in plasma and adipose tissue were measured by ELISA, RT-PCR and immunohistochemistry.ResultsIn this study, we showed that ANGPTL7 level was increased in the plasma of obese subjects (1249.05± 130.39 pg/mL) as compared to non-obese (930.34 ± 87.27 pg/mL) (p-Value = 0.032). ANGPTL7 Gene and protein expression levels in adipose tissue also showed over two fold increase. Physical exercise reduced circulating level of ANGPTL7 in the obese subjects to 740.98± 127.18 pg/mL, (p-Value = 0.007). ANGPTL7 expression in adipose tissue was also reduced after exercise. Finally, ANGPTL7 circulating level showed significant association with TG level in the obese subjects (R2 = 0.183, p-Value = 0.03).ConclusionIn conclusion, our data shows for the first time that obesity increases the level of ANGPTL7 in both plasma and adipose tissue. Increased expression of ANGPTL7 might play a minor role in the regulation of TG level in obese subjects either directly or through interaction with other ANGPTL protein members. Physical exercise reduced the level of ANGPTL7 highlighting the potential for targeting this protein as a therapeutic target for regulating dyslipidemia.

East Meets West: The Increasing Incidence of Inflammatory Bowel Disease in Asia as a Paradigm for Environmental Effects on the Pathogenesis of Immune-Mediated Disease

0094: The role of angiopoietin-like 4 in epithelial integrity during intestinal carcinogenesis

Latent Cytomegalovirus Infection Exacerbates Experimental Colitis

Mesenchymal stem cells (MSCs) are considered for cartilage engineering given their ability to differentiate into chondrocytes. Chondrogenic differentiation of MSCs is currently triggered by micromass culture in the presence of a member of the TGF-β superfamily. However, the main constituents of the cartilaginous matrix, aggrecan and type II collagen, are degraded at the end of the differentiation process through induction of matrix metallopeptidase (MMP)13. We hypothesized that MSCs undergoing chondrogenic differentiation produce an intermediate cytokine that triggers this matrix remodeling. Analysis of transcriptomic data identified angiopoietin-like 4 (ANGPTL4) as one of the most strongly up-regulated gene encoding a secreted factor during TGF-β-induced chondrogenesis. To gain insight into the role of ANGPTL4 during chondrogenesis, we used recombinant ANGPTL4 as well as a RNA interference approach. Addition of exogenous ANGPTL4 during the course of TGF-β-induced differentiation reduced the mRNA levels of aggrecan and type II collagen, although it increased those of MMP1 and MMP13. Accordingly, deposition of aggrecan and total collagens was diminished, whereas release of MMP1 and MMP13 was increased. Conversely, transfection of MSCs with an siRNA targeting ANGPTL4 prior to induction of chondrogenesis increased expression of type II collagen and aggrecan, whereas it repressed that of MMP1, MMP3, and MMP13. A neutralizing antibody against integrin αVβ5, a known receptor for ANGPTL4, mimicked some of the effects observed after siRNA-mediated ANGPTL4 silencing. Our data provide evidence that ANGPTL4 promotes cartilage matrix remodeling by inhibiting expression of its two key components and by up-regulating the level of certain MMPs.