High glucose-boosted inflammatory responses to lipopolysaccharide are suppressed by statin

Targeting Small GTPases and Their Prenylation in Diabetes Mellitus

A fundamental role of pancreatic β-cells to maintain proper blood glucose level is controlled by the Ras superfamily of small GTPases that undergo post-translational modifications, including prenylation. This covalent attachment with either a farnesyl or a geranylgeranyl group controls their localization, activity, and protein–protein interactions. Small GTPases are critical in maintaining glucose homeostasis acting in the pancreas and metabolically active tissues such as skeletal muscles, liver, or adipocytes. Hyperglycemia-induced upregulation of small GTPases suggests that inhibition of these pathways deserves to be considered as a potential therapeutic approach in treating T2D. This Perspective presents how inhibition of various points in the mevalonate pathway might affect protein prenylation and functioning of diabetes-affected tissues and contribute to chronic inflammation involved in diabetes mellitus (T2D) development. We also demonstrate the currently available molecular tools to decipher the mechanisms linking the mevalonate pathway’s enzymes and GTPases with diabetes.

Influence of the Periodontal Disease, the Most Prevalent Inflammatory Event, in Peroxisome Proliferator-Activated Receptors Linking Nutrition and Energy Metabolism

Periodontal disease is considered one of the main pathologic diseases occurring in humans. Its pathologic process involves inflammatory reactions producing periodontal bone resorption and the tooth loss. But some patients do not present an evident clinical inflammation with bone resorption, and in others, the inflammation is prominent without bone resorption. A key question could be to investigate a different way of responding to aggression. Inflammation requires a complex intracellular metabolic process, starting with the harmful recognition and activation of the inflammasome, continues the energy supply with the alteration of oxidative stress conditions, and finishes with the elimination of the aggression with autophagy/apoptosis mechanisms, then concludes with recovery. Peroxisome proliferator-activated receptors (PPARs) are essential molecules produced in inflammation, and its genes and its activation have been related to periodontal disease. Also, an important aspect is the influence of PPARs in bone metabolism; the main periodontitis symptom is bone loss and PPARγ activation that can downregulate the bone resorption in experimental periodontitis, PPARγ-coated titanium dental implant surfaces could carry the antiinflammatory gene and restrain inflammation. PPARs could be one of the meeting background points with atherosclerosis/cardiovascular disease, diabetes and metabolic syndrome showing a modified proinflammatory statement such as it is described in periodontitis.

High glucose-induced oxidative stress increases IL-8 production in human gingival epithelial cells

OBJECTIVE

Diabetes is often associated with increased prevalence and severity of periodontal disease. We hypothesized that gingival epithelial cells modify periodontal disease progression and predicted that hyperglycemia would activate an inflammatory response in human gingival epithelial cells (HGECs).

MATERIALS AND METHODS

We tested our hypothesis in immortalized HGECs (epi 4 cells) isolated from periodontal tissue and transfected with the simian virus 40 T antigen. The epi 4 cells were cultured in high (25 mM, HG) and normal (6 mM, NG) glucose conditions.

RESULTS

The epi 4 cells showed increased interleukin-8 (IL-8) protein secretion and mRNA expression when cultured in HG, compared with in NG. These effects were not associated with increased cell proliferation and were not observed in a hyperosmolar control group (normal glucose with 19 mM mannitol). Increased IL-8 secretion in HG was inhibited by pretreatment with an antioxidant, N-acetylcysteine, or a protein kinase C inhibitor, Ro31-8220. Hyperglycemia did not affect IL-8 secretion by gingival fibroblasts or periodontal ligament cells. In epi 4 cells, hyperglycemia also induced expression of toll-like receptor 2 (TLR2) but not TLR4.

CONCLUSION

These findings suggest a potential participation of epithelial cells in periodontal disease during diabetes by evoking an excessive host inflammatory response.

Statin intake is associated with MMP-1 level in gingival crevicular fluid of patients with periodontitis

BACKGROUND

This study was conducted to assess whether statin intake is associated with clinical parameters of periodontitis and matrix metalloproteinase (MMP) levels in gingival crevicular fluid (GCF) of non-diabetic and diabetic patients.

METHODS

We first determined the effect of simvastatin on MMP expression in mononuclear cells. We then recruited 117 non-diabetic and diabetic patients, who all had periodontitis and took or did not take statin, and measured periodontal probing depth (PPD) and clinical attachment level (CAL), and collected gingival crevicular fluid (GCF) to quantify MMPs.

RESULTS

The in vitro studies showed that simvastatin potently inhibited the expression of MMP-1, MMP-8, and MMP-9 upregulated by lipopolysaccharide (LPS) and high glucose in mononuclear cells. The patient study showed that, after adjusting for age and smoking status, PPD in diabetic patients on statin was significantly less than that in diabetic patients not on statin. MMP-1 level in GCF of non-diabetic and diabetic patients on statin was lower than that of non-diabetic and diabetic patients not on statin, respectively. No difference was found for MMP-8 and -9 levels in GCF.

CONCLUSION

Statin intake is associated with reduced PPD in diabetic patients and MMP-1 level in GCF in either non-diabetic or diabetic patients.

Periodontal CD14 mRNA expression is downregulated in patients with chronic periodontitis and type 2 diabetes

Background

Patients with type 2 diabetes mellitus (T2DM) have increased severity of periodontitis. Toll-like receptor (TLR)4, its co-receptors CD14 and MD-2, and adaptor MyD88 play pivotal roles in lipopolysaccharide (LPS)-triggered tissue inflammation and periodontitis. This study investigated the effects of T2DM and periodontitis on TLR4, CD14, MD-2 and MyD88 mRNA expression in surgically removed periodontal tissues.

Methods

Periodontal tissue specimens were collected from 14 patients without periodontitis and T2DM (Group 1), 15 patients with periodontitis alone (Group 2), and 7 patients with both periodontitis and T2DM (Group 3). The mRNA of TLR4, CD14, MD-2 and MyD88 was quantified using real-time PCR and compared between the groups.

Results

Statistical analysis showed that periodontal expression of CD14 mRNA was significantly reduced across Groups 1, 2 and 3 (p = 0.02) whereas the mRNA expression of TLR4, MD-2 and MyD88 was not significantly different among the groups. Furthermore, when patients in Groups 1 and 2 were combined (n = 22), the CD14 mRNA expression was significantly lower than that in patients of Group 1 (p = 0.04).

Conclusions

CD14 mRNA expression was downregulated across patients with neither periodontitis nor T2DM, patients with periodontitis alone and patients with both diseases, suggesting that CD14 mRNA expression is associated with a favorable host response or subjected to a negative feedback regulation.

Pleiotropic effects of statins on the treatment of chronic periodontitis--a systematic review

AIM

Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase and are an important group of hypolipidaemic drugs, widely used in the treatment of hypercholesterolaemia and cardiovascular disease. Some studies have shown that statins are able to modulate inflammation and alveolar bone loss.

METHODS

In order to evaluate whether statins could influence periodontal treatment, improving the clinical and radiographic parameters in chronic periodontitis, a systematic review was conducted in the databases PUBMED and BIREME, searching for articles in English and Portuguese, published between the years 2004 and 2014, using the combined keywords statin, periodontal disease, periodontitis and alveolar bone. Studies regarding the treatment of chronic periodontitis in humans, blind or double-blind, retrospective cohort or randomized controlled trials that used statins topically or systemically were selected.

RESULTS

Statins have important anti-inflammatory and immune effects, reducing levels of C-reactive protein and matrix metalloproteinases and their intermediate products, such as tumour necrosis factor-α, and are also able to inhibit the adhesion and extravasation of leukocytes, which block the co-stimulation of T cells. Statins reduce bone resorption by inhibiting osteoclast formation and lead to increased apoptosis of these cells. The effect of statins on bone formation is related to the increased gene expression of bone morphogenetic protein in osteoblasts.

CONCLUSION

Although we found biological mechanisms and clinical results that show lower alveolar bone loss and reduction of clinical signs of inflammation, further studies are needed to evaluate the clinical applicability of statins in the routine treatment of chronic periodontitis.

Simvastatin inhibits lipopolysaccharide-induced osteoclastogenesis and reduces alveolar bone loss in experimental periodontal disease

BACKGROUND AND OBJECTIVE

Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase and have anti-inflammatory effects independent of cholesterol lowering. Recent clinical studies have indicated that statin intake has a beneficial effect on periodontal disease. However, the underlying mechanisms have not been well understood. In the current study, we employed a rat model with lipopolysaccharide (LPS)-induced periodontal disease and determined the effect of simvastatin, a commonly prescribed statin, on osteoclastogenesis, gingival inflammation and alveolar bone loss.

MATERIAL AND METHODS

Sprague-Dawley rats were injected with Aggregatibacter actinomycetemcomitans LPS in periodontal tissue three times per week for 8 wk and part of the rats with LPS injection were also given simvastatin via gavage. After the treatments, the rat maxillae were scanned by microcomputed tomography and the images were analyzed to determine alveolar bone loss. To explore the underlying mechanisms, the effect of simvastatin on osteoclastogenesis and gingival expression of proinflammatory cytokines were also determined by tartrate-resistant acid phosphatase staining and real-time polymerase chain reaction assays, respectively.

RESULTS

Results showed that LPS treatment markedly increased bone loss, but administration of simvastatin significantly alleviated the bone loss. Results also showed that LPS treatment stimulated osteoclastogenesis and the expression of inflammatory cytokines, but simvastatin significantly modulates the stimulatory effect of LPS on osteoclastogenesis and cytokine expression.

CONCLUSION

This study demonstrated that simvastatin treatment inhibits LPS-induced osteoclastogenesis and gingival inflammation and reduces alveolar bone loss, indicating that the intake of simvastatin may hinder the progression of periodontal disease.

Atorvastatin suppresses inflammatory response induced by oxLDL through inhibition of ERK phosphorylation, IκBα degradation, and COX-2 expression in murine macrophages

Macrophages crosstalk with oxidized low-density lipoprotein (oxLDL), play a critical role in the initiation, progression, and subsequently stability of atherosclerotic plaques. Statins, inhibitors of HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase, reduce the expression of inflammatory proteins in addition to their lipid-lowering action. However, the effect and detailed anti-inflammation mechanisms of statins in macrophages induced by oxLDL remain unclearly. In the present study, we investigated the effect of atorvastatin on inflammatory response upon oxLDL stimulation in murine macrophages and analyzed the underlying mechanisms. Tumor necrosis factor (TNF)α and monocyte chemoattractant protein-1 (MCP-1) mRNA levels were assayed by real-time PCR. The expression of cyclooxygenases-2 (COX-2) was detected by real-time PCR and Western blotting. While mitogen-activated protein kinase (MAPK) phosphorylation and IκBα degradation were determined by Western blotting. Our results showed that exposure of RAW264.7 cells to oxLDL, substantially changed the morphology of the cells and increased TNFα and MCP-1 secretion. While pretreatment with atorvastatin resulted in a significant inhibition of oxLDL-induced morphological alteration and inflammatory cytokines expression in a dose-dependent fashion. Further investigation of the molecular mechanism revealed that oxLDL upregulated the transcription and protein expression of COX-2 in a time-dependent manner. Whereas, pretreatment with atorvastatin suppressed COX-2 expression, MAPK activation and IκBα degradation. Thus, we conclude that the anti-inflammatory effect of atorvastatin is mediated through the inhibition of proinflammatory COX-2. Furthermore, suppression of ERK phosphorylation and IκBα degradation is involved in this regulation. Our findings provide a novel evidence that statins suppress inflammatory response, exert its anti-atherogenic actions via against inflammation beyond cholesterol-lowing effect.

Different signaling mechanisms regulating IL-6 expression by LPS between gingival fibroblasts and mononuclear cells: seeking the common target

To reduce connective tissue IL-6 level stimulated by LPS, it is essential to control IL-6 expression in both mononuclear cells and fibroblasts. However, it is unclear whether the regulatory mechanisms for both cells are similar or not. In this study, we found that signaling pathways mediating LPS-stimulated IL-6 in mononuclear U937 cells and fibroblasts were different. Furthermore, our studies showed that while LPS activated AP-1 and NFκB in U937 cells, it only activated NFκB in fibroblasts. Analysis of nuclear AP-1 subunits showed that LPS stimulated c-Fos, Fra-1 and Jun D activities in U937 cells, but not fibroblasts. The lack of ERK involvement in LPS-stimulated IL-6 in fibroblasts was further supported by the observations that simvastatin, which is known to target ERK-AP-1, failed to inhibit LPS-stimulated IL-6 by fibroblasts. Finally, we showed that targeting NFκB pathway was highly effective in inhibition of LPS-stimulated IL-6 in coculture of U937 cells and fibroblasts.

Cholesterol, C-Reactive Protein, and Periodontitis: HMG-CoA-Reductase Inhibitors (Statins) as Effect Modifiers

Common risk factors of periodontitis and cardiovascular diseases fuel the debate on interrelationships between them. The aim is to prove whether statins may influence periodontal parameters by affecting either of these factors. Out of the 4,290 subjects of SHIP (Study of Health in Pomerania), we included subjects aged >30 years (219 with statins, 2937 without) and excluded edentulous. We determined periodontal measures, cholesterol fractions, and inflammation markers. Statin use and periodontal risk factors were assessed. Gingival plaque and periodontal attachment loss were associated with systemic LDL cholesterol (P < 0.001) and C-reactive protein CRP (P = 0.019) revealing interaction with statin use. When adjusted for age, sex, smoking, diabetes, education, and dental service, statins were identified as effect modifiers abolishing the relationship between attachment loss and LDL and between gingival plaque and LDL (interactions P < 0.001). No statin-related interaction was detected with increase in CRP. The interaction supports the view of inter-relationships between periodontal and systemic inflammatory mediators.

Matrix metalloproteinase-8 expression in periodontal tissues surgically removed from diabetic and non-diabetic patients with periodontal disease

BACKGROUND

Although it is known that periodontal matrix metalloproteinase-8 (MMP-8) expression is associated with periodontal disease, the information concerning the periodontal MMP-8 expression in diabetic patients with periodontal disease is insufficient.

MATERIALS AND METHODS

Periodontal tissue specimens were collected from seven patients without periodontal disease and diabetes (Group 1), 15 patients with periodontal disease alone (Group 2) and 10 patients with both periodontal disease and diabetes (Group 3). The frozen sections were prepared and MMP-8 protein expression was detected using immunohistochemistry and quantified. For in vitro study, human U937 mononuclear cells were pre-exposed to normal or high glucose and then treated with lipopolysaccharide (LPS).

RESULTS

The nonparametric Kruskal-Wallis test showed that the difference in MMP-8 protein levels among the three groups were statistically significant (p = 0.003). Nonparametric analysis using Jonckheere-Terpstra test showed a tendency of increase in periodontal MMP-8 levels across Group 1 to Group 2 to Group 3 (p = 0.0002). In vitro studies showed that high glucose and LPS had a synergistic effect on MMP-8 expression.

CONCLUSION

Our current study showed an increasing trend in MMP-8 protein expression levels across patients without both periodontal disease and diabetes, patients with periodontal disease alone and patients with both diseases.

Expression of periodontal interleukin-6 protein is increased across patients with neither periodontal disease nor diabetes, patients with periodontal disease alone and patients with both diseases

BACKGROUND AND OBJECTIVE

Epidemiological studies have established that patients with diabetes have an increased prevalence and severity of periodontal disease. Interleukin (IL)-6, a multifunctional cytokine, plays a role in the tissue inflammation that characterizes periodontal disease. Our recent study has shown a trend of increase in periodontal IL-6 expression at the mRNA level across patients with neither periodontal disease nor diabetes, patients with periodontal disease alone and patients with both diseases. However, the periodontal IL-6 expression at the protein level in these patients has not been investigated.

MATERIAL AND METHODS

Periodontal tissue specimens were collected from eight patients without periodontal disease and diabetes (group 1), from 17 patients with periodontal disease alone (group 2) and from 10 patients with both periodontal disease and diabetes (group 3). The frozen sections were prepared from these tissue specimens and IL-6 protein expression was detected and quantified.

RESULTS

The nonparametric Kruskal-Wallis test showed that the difference in IL-6 protein levels among the three groups was statistically significant (p = 0.035). Nonparametric analysis using the Jonckheere-Terpstra test showed a tendency of increase in periodontal IL-6 protein levels across group 1 to group 2 to group 3 (p = 0.006). Parametric analysis of variance (ANOVA) on IL-6 protein levels showed that neither age nor gender significantly affected the difference of IL-6 levels among the groups.

CONCLUSION

Periodontal IL-6 expression at the protein level is increased across patients with neither periodontal disease nor diabetes, patients with periodontal disease alone and patients with both diseases.

IL-6 and high glucose synergistically upregulate MMP-1 expression by U937 mononuclear phagocytes via ERK1/2 and JNK pathways and c-Jun

Matrix metalloproteinases (MMPs) play a pivotal role in tissue remodeling and destruction in inflammation-associated diseases such as cardiovascular disease and periodontal disease. Although it is known that interleukin (IL)-6 is a key proinflamatory cytokine, it remains unclear how IL-6 regulates MMP expression by mononuclear phagocytes. Furthermore, it remains undetermined how IL-6 in combination with hyperglycemia affects MMP expression. In the present study, we investigated the regulatory effect of IL-6 alone or in combination with high glucose on MMP-1 expression by U937 mononuclear phagocytes. We found that IL-6 is a powerful stimulator for MMP-1 expression and high glucose further augmented IL-6-stimulated MMP-1 expression. We also found that high glucose, IL-6, and lipopolysaccharide act in concert to stimulate MMP-1 expression. In the studies to elucidate underlying mechanisms, the extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) pathways were found to be required for stimulation of MMP-1 by IL-6 and high glucose. We also observed that IL-6 and high glucose stimulated the expression of c-Jun, a key subunit of AP-1 known to be essential for MMP-1 transcription. The role of c-Jun in MMP-1 expression was confirmed by the finding that suppression of c-Jun expression by RNA interference significantly inhibited MMP-1 expression. Finally, we demonstrated that similarly to U937 mononuclear phagocytes, IL-6 and high glucose also stimulated MMP-1 secretion from human primary monocytes. In conclusion, this study demonstrated that IL-6 and high glucose synergistically stimulated MMP-1 expression in mononuclear phagocytes via ERK and JNK cascades and c-Jun upregulation.

Interleukin-18 is a strong predictor of cardiovascular events in elderly men with the metabolic syndrome: synergistic effect of inflammation and hyperglycemia

OBJECTIVE

The aim of this study was to investigate the role of inflammatory markers as potential predictors of cardiovascular events in subjects with and without the metabolic syndrome.

RESEARCH DESIGN AND METHODS

This was a post hoc analysis from the Diet and Omega-3 Intervention Trial (DOIT), comprising 563 elderly men with (n = 221) and without (n = 342) metabolic syndrome. Circulating inflammatory markers were measured.

RESULTS

During 3 years, 68 cardiovascular events were recorded. In the total population, C-reactive protein (CRP) (P < 0.001), interleukin-18 (IL-18) (P = 0.008), and IL-6 (P = 0.003) were elevated in subjects with events. In subjects with metabolic syndrome, IL-18 was the strongest predictor (adjusted odds ratio 2.9 [95% CI 1.1-7.8]). In subjects without metabolic syndrome, only CRP seemed to be an independent predictor (3.3 [1.5-7.3]). There was a significant interaction between fasting glucose and IL-18 (P = 0.008) and IL-6 (P = 0.024) but not CRP. Elevated fasting glucose (>6.2 mmol/l) markedly increased the predictive power of inflammatory markers (IL-18: 5.5 [1.4-21.1], IL-6: 3.5 [1.0-11.8], and CRP: 3.5 [1.0-11.9]). For IL-18, there was a stepwise increase in event rate by quartiles of fasting glucose.

CONCLUSIONS

IL-18 was an independent predictor of cardiovascular events in subjects with metabolic syndrome and even more so in the presence of elevated fasting glucose. Our findings suggest a mutually potentiating effect of hyperglycemia and inflammation in cardiovascular risk prediction.

Simvastatin suppresses LPS-induced MMP-1 expression in U937 mononuclear cells by inhibiting protein isoprenylation-mediated ERK activation

Matrix metalloproteinase (MMP) plays a crucial role in periodontal disease and is up-regulated by oral Gram-negative, pathogen-derived LPS. In this study, we reported that simvastatin, a 3-hydroxyl-3-methylglutaryl-CoA reductase inhibitor, effectively inhibited LPS-stimulated MMP-1 as well as MMP-8 and MMP-9 expression by U937 mononuclear cells. Our studies showed that the geranylgeranyl transferase inhibitor inhibited LPS-stimulated MMP-1 expression, and addition of isoprenoid intermediate geranylgeranyl pyrophosphate (GGPP) reduced the inhibitory effect of simvastatin on LPS-stimulated MMP-1 expression. We also demonstrated that simvastatin inhibited the activation of Ras and Rac, and the inhibition was abolished by addition of GGPP. The above results indicate that protein isoprenylation is involved in the regulation of MMP-1 expression by LPS and simvastatin. Moreover, we showed that simvastatin inhibited LPS-stimulated nuclear AP-1, but not NF-kappaB activity, and the inhibition was reversed by addition of GGPP. Simvastatin also inhibited LPS-stimulated ERK but not p38 MAPK and JNK. Finally, we showed that the inhibition of LPS-stimulated ERK activation by simvastatin was reversed by GGPP. Taken together, this study showed that simvastatin suppresses LPS-induced MMP-1 expression in U937 mononuclear cells by targeting protein isoprenylation-mediated ERK activation.

Distinct monocyte gene-expression profiles in autoimmune diabetes

OBJECTIVE

There is evidence that monocytes of patients with type 1 diabetes show proinflammatory activation and disturbed migration/adhesion, but the evidence is inconsistent. Our hypothesis is that monocytes are distinctly activated/disturbed in different subforms of autoimmune diabetes.

RESEARCH DESIGN AND METHODS

We studied patterns of inflammatory gene expression in monocytes of patients with type 1 diabetes (juvenile onset, n = 30; adult onset, n = 30) and latent autoimmune diabetes of the adult (LADA) (n = 30) (controls subjects, n = 49; type 2 diabetic patients, n = 30) using quantitative PCR. We tested 25 selected genes: 12 genes detected in a prestudy via whole-genome analyses plus an additional 13 genes identified as part of a monocyte inflammatory signature previously reported.

RESULTS

We identified two distinct monocyte gene expression clusters in autoimmune diabetes. One cluster (comprising 12 proinflammatory cytokine/compound genes with a putative key gene PDE4B) was detected in 60% of LADA and 28% of adult-onset type 1 diabetic patients but in only 10% of juvenile-onset type 1 diabetic patients. A second cluster (comprising 10 chemotaxis, adhesion, motility, and metabolism genes) was detected in 43% of juvenile-onset type 1 diabetic and 33% of LADA patients but in only 9% of adult-onset type 1 diabetic patients.

CONCLUSIONS

Subgroups of type 1 diabetic patients show an abnormal monocyte gene expression with two profiles, supporting a concept of heterogeneity in the pathogenesis of autoimmune diabetes only partly overlapping with the presently known diagnostic categories.

High glucose and interferon gamma synergistically stimulate MMP-1 expression in U937 macrophages by increasing transcription factor STAT1 activity

Recent diabetes control and complications trial and epidemiology of diabetes interventions and complications (DCCT/EDIC) and other clinical studies have reported that glucose control in patients with diabetes leads to a significant reduction of cardiovascular events and atherosclerosis, indicating that hyperglycemia plays an essential role in cardiovascular disease in diabetic patients. Although several mechanisms by which hyperglycemia promotes atherosclerosis have been proposed, it remains unclear how hyperglycemia promotes atherosclerosis by interaction with inflammatory cytokines. To test our hypothesis that hyperglycemia interplays with interferon gamma (IFN gamma), a key factor involved in atherosclerosis, to up-regulate the expression of genes such as matrix metalloproteinases (MMPs) and cytokines that are involved in plaque destabilization, U937 macrophages cultured in medium containing either normal or high glucose were challenged with IFN gamma and the expression of MMPs and cytokines were then quantified by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Results showed that high glucose and IFN gamma had a synergistic effect on the expression of MMP-1, MMP-9 and IL-1 beta. High glucose also enhanced IFN gamma-induced priming effect on lipopolysaccharide (LPS)-stimulated MMP-1 secretion. Furthermore, high glucose and IFN gamma exert the synergistic effect on MMP-1 expression by enhancing STAT1 phosphorylation and STAT1 transcriptional activity. In summary, this study revealed a novel mechanism potentially involved in diabetes-promoted cardiovascular disease.