Hyperglycemia-induced accumulation of advanced glycosylation end products in fibroblast-like synoviocytes promotes knee osteoarthritis

Osteoarthritis (OA) is significantly associated with diabetes, but how hyperglycemia induces or aggravates OA has not been shown. The synovium plays a critical role in cartilage metabolism and substance exchange. Herein, we intended to investigate whether and how hyperglycemia affects the occurrence and progression of OA by influencing the synovium. In patients with knee OA and diabetes (DM OA), we found a more severe inflammatory response, higher endoplasmic reticulum stress (ERS) levels, and more advanced glycosylation end products (AGEs) accumulation in the synovium than in patients without diabetes. Subsequently, we found similar results in the DM OA group in a rat model. In the in vitro cocultivation system, high glucose-stimulated AGEs accumulation, ERS, and inflammation in rat fibroblast-like synoviocytes (FLSs), which resulted in chondrocyte degeneration due to inflammatory factors from FLSs. Furthermore, in the synovium of the DM OA group and FLSs treated with high glucose, the expression of glucose transporter 1 (GLUT1) and its regulatory factor hypoxia-inducible factor (HIF)-1α was increased significantly. Inhibitors of HIF-1α, GLUT1 or AGEs receptors attenuated the effect of high glucose on chondrocyte degradation in the FLS-chondrocyte coculture system. In summary, we demonstrated that hyperglycemia caused AGEs accumulation in FLSs via the HIF-1α-GLUT1 pathway, which increases the release of inflammatory factors from FLSs, subsequently inducing chondrocyte degradation and promoting OA progression.

Advanced glycosylation end products inhibit the proliferation of bone-marrow stromal cells through activating MAPK pathway

Background The purpose of present study was to explore the mechanism of nuclear factor-kappa B (NF-κB), phosphatidylinositol 3-kinase (PI3K)/protein kinase B(PKB/Akt) and mitogen-activated protein kinase (MAPK) signaling pathways after intervention of advanced glycosylation end products (AGEs) on rat bone-marrow stromal cells (BMSCs). Methods Prepare and identify AGEs. BMSCs were isolated from 16 SD rats and cultured with different concentration of AGEs. Cell viability was detected by cell counting kit-8 (CCK-8). BMSCs were cultured with AGEs (0.25 mg/ml) for 30 min, 12 h, 24 h, 72 h and 120 h. In addition, BMSCs were cultured with AGEs, AGEs + JNK inhibitor and AGEs + P38 inhibitor for 24 h and 48 h, respectively. Western blotting and RT-PCR were used to determine the protein and mRNA expression levels, respectively. Results Cell viability of BMSCs was significantly correlated with concentration and effect time of AGEs (P < 0.05), and the most appropriate concentration was 0.25 mg/ml. AGEs stimulation significantly increased the protein expression levels of NF-κB p65, JNK, p38 (P < 0.05), decreased IκB (P < 0.05), but had no effect on the protein expression of Akt in BMSCs (P > 0.05). At the mRNA level, JNK and p38 inhibitors significantly reduced the levels of NF-κB p65, p38 and JNK, increased IκB (P > 0.05), but had no effect on Akt in BMSCs (P > 0.05). At the protein level, JNK and p38 inhibitors notably decreased the expression of NF-κB p65, p38, p-JNK, P-IκB and JNK (P < 0.001), and increased IκB (P < 0.05). Conclusion Advanced glycosylation end products can inhibit the proliferation of bone-marrow stromal cells through activating MAPK pathway.

How Does Glycation Affect Binding Parameters of the Albumin-Gliclazide System in the Presence of Drugs Commonly Used in Diabetes? In Vitro Spectroscopic Study

In this research, the selected drugs commonly used in diabetes and its comorbidities (gliclazide, cilazapril, atorvastatin, and acetylsalicylic acid) were studied for their interactions with bovine serum albumin—native and glycated. Two different spectroscopic methods, fluorescence quenching and circular dichroism, were utilized to elucidate the binding interactions of the investigational drugs. The glycation process was induced in BSA by glucose and was confirmed by the presence of advanced glycosylation end products (AGEs). The interaction between albumin and gliclazide, with the presence of another drug, was confirmed by calculation of association constants (0.11–1.07 × 104 M−1). The nature of changes in the secondary structure of a protein depends on the drug used and the degree of glycation. Therefore, these interactions may have an influence on pharmacokinetic parameters.

Involvement of RAGE and Oxidative Stress in Inflammatory and Infectious Skin Diseases

The surface receptor for advanced glycosylation end-products (RAGE) and its soluble (sRAGE) and endogenous secretory (EN-RAGE) forms belong to the superfamily of toll-like receptors and play important roles in inflammation and autoimmunity, directly or through binding with advanced glycosylation end-products (AGE) and advanced oxidation protein products (AOPP). We reviewed the literature on the role of RAGE in skin diseases. Research in this field is still rather limited (28 articles) but suggests the involvement of RAGE and RAGE-related pathways in chronic inflammatory diseases (lupus, psoriasis, atopic dermatitis, and lichen planus), infectious diseases (leprosy, Staphylococcus aureus-induced skin lesions), alterations of the repairing processes in diabetic skin, systemic sclerosis, and ulcers. These data prompt further research in this field, which not only will be useful to better understand the pathogenetic mechanisms of diseases, but is also likely to have intriguing clinical implications. Indeed, when their role in the complex and multifactorial inflammatory balance will be adequately defined, RAGE and related molecules could be used as markers of disease severity and/or response to treatment. Moreover, future promising therapeutic perspectives could be topical administration of some of these molecules (e.g., sRAGE) to modulate local inflammatory response and/or the development of anti-RAGE antibodies for systemic treatment.

Serum Lipidome and Glucose Metabolism Uncover Vulnerabilities in Myelodysplasia and Secondary Acute Myelogenous Leukemia

Background Secondary acute myelogenous leukemia (sAML) is highly aggressive and molecularly heterogenous. Previous reports have demonstrated differential serum lipid expression among hemopoietic malignancies (i.e AML, myelodysplastic syndrome (MDS) and acute lymphoblastic leukemia (ALL). Such a distinct serum lipidome among hemopoietic disorders suggest "unique oncogenic metabolic addiction" of leukemia initiating cells (LICs). MDS to AML transition is characterized by clonal evolution [i.e severe aneuploidy, high P53 frequency etc.] and chemorefractoriness. However, mechanism(s) for transformation are not entirely understood. In this study, we investigate serum lipidome and "proxy" of glucose [HbA1C] metabolism among: (1) low risk, (2) high risk MDS and (3) sAML patients (pts) to identify features that may suggest disease specific vulnerabilities. Methods After IRB approval, 214 pts were selected for analysis. ANOVA was used to detect differential expression of total cholesterol (TC), low density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides (TAG) among low risk, high risk and sAML pts. Multivariate linear regression model was performed to evaluate the independent effect of confounders on relevant lipid modifications observed among subtypes of MDS and sAML pts. SAS software was used for data processing. Results 69/214 (32.2%), 26/214 (12.1%), 35/214 (16.3%), 35/214 (16.3%), 28/214 (13.08%), 21/214 (9.8%) were sAML, very low (VLR), low (LR), intermediate (I), high (H) and very high risk (VHR) MDS. Median age (range) was 68 y (42-91), 68 y (22-87), 70 y (55-91), 76 (53-88), 72 y (60-85) and 74 y (54-84), for sAML, VLR, LR, I, H and VHR, p=0.0001. In sAML, VLR, LR, I, HR and VHR MDS TC was 177 mg/dL, 150 mg/dL, 126 mg/dL, 134 mg/dL, 125 mg/dL and 122 mg/dL, p=0.0001; LDL was 113.4 mg/dL, 81.3 mg/dL, 67.8 mg/dL, 72 mg/dL, 63.2 mg/dL and 70.8 mg/dL, p=0.0001; HDL 35.8 mg/dL, 39.2 mg/dL, 36.1 mg/dL, 40 mg/dL, 33.7 mg/dL, 32.05 mg/dL, p=0.40; TAG 134 mg/dL, 140 mg/dL, 109 mg/dL, 120 , mg/dL 134 mg/dL, 98 mg/dL, p=0.1. Given "similarities" among MDS subgroups, "MDS lipid data" was compared vs sAML. Median TC, LDL, HDL and TAG among sAML vs MDS pts was 179.1 mg/dL vs 130.4 mg/dL, p=0.0001; 113 mg/dL vs 70.1 mg/dL, p=0.0001; 38.6 mg/dL vs 36.7 mg/dL, p=0.5; 142 mg/dL vs 116.6 mg/dL, p=0.056, respectively. 20/89 (22.7%) vs 69/89 (77.53%) sAML vs MDS pts, respectively were diabetic, p=0.002, OR =2.62; 95% CI 1.40-4.90. However, data extracted from 82 pts (16 sAML and 66 MDS, each) demonstrated that hemoglobin A1C (HbA1C) was 7.84% vs 6.34%, in sAML vs MDS, respectively, p=0.009. Multivariate linear regression accounting for age, blast count, BMI, DM status and HbA1C showed that higher TC, LDL and HbA1C were independent predictors of sAML. Conclusions While this study is restricted to demonstrate distinct lipid and metabolic profile between sAML and MDS, our results suggest blastic phase dependency on higher serum cholesterol and possibly higher advanced glycosylation. As compared to MDS, our data highlights the possibility that sAML induces serum Lipidome modifications that may "hijack endogenous lipogenesis" to favor TC, LDL and possibly TAG production. Additionally, despite larger number of patients is needed to confirm our results, higher HbA1C potentially initiates advanced glycosylation facilitating blastic conversion in MDS pts. Disclosures Rivero: Incyte: Membership on an entity's Board of Directors or advisory committees; agios: Membership on an entity's Board of Directors or advisory committees; celgene: Membership on an entity's Board of Directors or advisory committees.

The receptor for advanced glycosylation end products, RAGE (AGER) is differentially expressed in non-small cell lung cancer and associates with patient survival.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer death in the United States (1). We mined published microarray data (2, 3, 4) to identify differentially expressed genes in NSCLC. We found that the gene encoding the advanced glycosylation end-product specific receptor, AGER (5), also known as RAGE, was among the genes whose expression was most quantitatively different in tumors from patients with NSCLC as compared to the lung. AGER expression was significantly decreased in NSCLC tumors as compared to the lung, and lower expression of AGER in patient tumors was significantly associated with worse overall survival. AGER may be important for initiation or progression of non-small cell lung cancer in humans.

Soluble advanced glycosylation receptor is a potential target for the treatment of neutrophilic asthma

Background Neutrophilic asthma (NA) was a subtype of asthma. Soluble advanced glycosylation receptor (sRAGE) was considered to be associated with the neutrophilic airway. However, the role of sRAGE in NA still limited. Methods A NA mouse model was established and the levels of sRAGE in the bronchoalveolar lavage fluid (BALF) were measured by ELISA. Hematoxylin-eosin (HE) and Masson trichrome staining were used to identifying airway remodeling. Adeno-associated virus 9 (AAV9) overexpressed sRAGE and inhibitors for HMGB1, RAGE, and PI3K were used to intervene NA mouse model via tail-vein injection and intraperitoneally injection. Expressions of airway remodeling, EMT, and signaling markers were detected using qRT-PCR or western blotting. The levels of IL-17 and IL-6 in BALF were measured by ELISA. HMGB1 was applied to induce EMT of human bronchial epithelial cells (16HBE), then E-cadherin and vimentin expressions were examined after sRAGE, RAGE inhibitor, and PI3K inhibitor administration. Results sRAGE levels were significantly reduced in BALF and the airway remodeling was observed in the NA mouse model. AAV9-sRAGE significantly inhibited the neutrophilic airway inflammation, airway remodeling, and the expression of IL-17, IL-6, TGF-β1, RAGE, PI3K, and EMT markers -E-cadherin and vimentin in vivo. HMGB1 inhibitor, RAGE inhibitor, and PI3K inhibitor upregulated E-cadherin level. Moreover, HMGB1 promoted the EMT process via RAGE/PI3K in 16HBE cells and sRAGE reversed HMGB1- induced EMT in vitro. Conclusion sRAGE levels decrease in the mouse model with NA. sRAGE treatment attenuates neutrophilic airway inflammation, airway remodeling, and EMT. This suggests sRAGE may yield benefits in the treatment of NA.

Influences of advanced glycosylation end products on the inner blood–retinal barrier in a co-culture cell model in vitro

Advanced glycosylation end products (AGEs) are harmful factors that can damage the inner blood–retinal barrier (iBRB). Rat retinal microvascular endothelial cells (RMECs) were isolated and cultured, and identified by anti-CD31 and von Willebrand factor polyclonal antibodies. Similarly, rat retinal Müller glial cells (RMGCs) were identified by H&E staining and with antibodies of glial fibrillary acidic protein and glutamine synthetase. The transepithelial electrical resistance (TEER) value was measured with a Millicell electrical resistance system to observe the leakage of the barrier. Transwell cell plates for co-culturing RMECs with RMGCs were used to construct an iBRB model, which was then tested with the addition of AGEs at final concentrations of 50 and 100 mg/L for 24, 48, and 72 h. AGEs in the in vitro iBRB model constructed by RMEC and RMGC co-culture led to the imbalance of the vascular endothelial growth factor (VEGF) and pigment epithelial derivative factor (PEDF), and the permeability of the RMEC layer increased because the TEER decreased in a dose- and time-dependent manner. AGEs increased VEGF but lowered PEDF in a dose- and time-dependent manner. The intervention with AGEs led to the change of the transendothelial resistance of the RMEC layer likely caused by the increased ratio of VEGF/PEDF.