Glucose, VEGF-A, and diabetic complications

Protective effects of nattokinase against microvasculopathy and neuroinflammation in diabetic retinopathy

AIMS

Diabetic retinopathy (DR) is a significant global public health concern. Alternative, safe, and cost-effective pharmacologic approaches are warranted. We aimed to investigate the therapeutic potential of nattokinase (NK) for early DR and the underlying molecular mechanism.

METHODS

A mouse model of diabetes induced by streptozotocin was utilized and NK was administered via intravitreal injection. Microvascular abnormities were evaluated by examining the leakage from blood-retinal barrier dysfunction and loss of pericytes. Retinal neuroinflammation was examined through the assessment of glial activation and leukostasis. The level of high mobility group box 1 (HMGB1) and its downstream signaling molecules was evaluated following NK treatment.

RESULTS

NK administration significantly improved the blood-retinal barrier function and rescued pericyte loss in the diabetic retinas. Additionally, NK treatment inhibited diabetes-induced gliosis and inflammatory response and protected retinal neurons from diabetes-induced injury. NK also improved high glucose-induced dysfunction in cultured human retinal micrangium endothelial cells. Mechanistically, NK regulated diabetes-induced inflammation partially by modulating HMGB1 signaling in the activated microglia.

CONCLUSIONS

This study demonstrated the protective effects of NK against microvascular damages and neuroinflammation in the streptozotocin-induced DR model, suggesting that NK could be a potential pharmaceutical agent for the treatment of DR.

Comparative three-dimensional genome architectures of adipose tissues provide insight into human-specific regulation of metabolic homeostasis

Elucidating the regulatory mechanisms of human adipose tissues (ATs) evolution is essential for understanding human-specific metabolic regulation, but the functional importance and evolutionary dynamics of three-dimensional (3D) genome organizations of ATs are not well defined. Here, we compared the 3D genome architectures of anatomically distinct ATs from humans and six representative mammalian models. We recognized evolutionarily conserved and human-specific chromatin conformation in ATs at multiple scales, including compartmentalization, topologically associating domain (TAD), and promoter-enhancer interactions (PEI), which have not been described previously. We found PEI are much more evolutionarily dynamic with respect to compartmentalization and topologically associating domain. Compared to conserved PEIs, human-specific PEIs are enriched for human-specific sequence, and the binding motifs of their potential mediators (transcription factors) are less conserved. Our data also demonstrated that genes involved in the evolutionary dynamics of chromatin organization have weaker transcriptional conservation than those associated with conserved chromatin organization. Furthermore, the genes involved in energy metabolism and the maintenance of metabolic homeostasis are enriched in human-specific chromatin organization, while housekeeping genes, health-related genes, and genetic variations are enriched in evolutionarily conserved compared to human-specific chromatin organization. Finally, we showed extensively divergent human-specific 3D genome organizations among one subcutaneous and three visceral ATs. Together, these findings provide a global overview of 3D genome architecture dynamics between ATs from human and mammalian models and new insights into understanding the regulatory evolution of human ATs.

ANRIL regulates multiple molecules of pathogenetic significance in diabetic nephropathy

Background

Hyperglycemia-induced transcriptional alterations lead to aberrant synthesis of a large number of pathogenetic molecules leading to functional and structural damage to multiple end organs including the kidneys. Diabetic nephropathy (DN) remains a major cause of end stage renal disease. Multiple epigenetic mechanisms, including alteration of long non-coding RNAs (lncRNAs) may play a significant role mediating the cellular transcriptional activities. We have previously shown that lncRNA ANRIL may mediate diabetes associated molecular, functional and structural abnormalities in DN. Here we explored downstream mechanisms of ANRIL alteration in DN.

Methods

We used renal cortical tissues from ANRIL knockout (KO) mice and wild type (WT) mice, with or without streptozotocin (STZ) induced diabetes for RNA sequencing. The differentially expressed genes were identified using edgeR and DESeq2 computational methods. KEGG and Reactome pathway analyses and network analyses using STRING and IPA were subsequently performed.

Results

Diabetic animals showed hyperglycemia, reduced body weight gain, polyuria and increased urinary albumin. Both albuminuria and polyuria were corrected in the KO diabetic mice. RNA analyses showed Diabetes induced alterations of a large number of transcripts in the wild type (WT) animals. ANRIL knockout (KO) prevented a large number of such alterations. The altered transcripts include metabolic pathways, apoptosis, extracellular matrix protein synthesis and degradation, NFKB related pathways, AGE-RAGE interaction pathways etc. ANRIL KO prevented majority of these pathways.

Conclusion

These findings suggest that as ANRIL regulates a large number of molecules of pathogenetic significance, it may potentially be a drug target for DN and other chronic diabetic complications.

Polymorphisms of vascular endothelial growth factor-2578C/A rs699947 are risk factors for diabetic retinopathy in type-2 diabetes mellitus patients in Bali, Indonesia

BACKGROUND

Diabetic retinopathy (DR) is one of the complications in diabetes mellitus (DM) which caused by microvascular-damage in the retina due to long termmetabolic changes in diabetes. To date, there has been much research targeted on the determinant of genetic identification in DR patients. In DR, Vascular Endothelial Growth Factor (VEGF) gene is accountable for breaking down the blood-retinal barrier and implicated in the role of neovascularization. It is thought that the polymorphism of VEGF -2578C/A (rs699947) contributed to the development of diabetic retinopathy in type 2 DM.

AIM

To determine whether the polymorphisms of VEGF-2578C/A are the risk factors for DR in type 2 DM patients in Bali, Indonesia.

METHODS

This study is a case-control model comparing 33 cases DR patients in type-2 diabetes mellitus and 35 cases of non-DR as controls in Balinese ethnic. Polymorphisms of VEGF-2578C/A were examined by PCR analysis and DNA sequencing on rs699947 to identify any variation in A/C/T allele distribution. Chi-square test was used to analyze the data and determine the relation of polymorphism and DR.

RESULTS

This research showed the genetic variation existence in VEGF-2578C/A polymorphism significantly (p = 0,000) with C allele was higher in the DR group, in contrast, A and T allele were greater in the non-DR group compared to DR group. The result showed that C allele in VEGF-2578 contributed as a risk factor (OR = 13.05; 95% CI = 2.69-63.18; p = 0.001) for DR in type-2 DM (T2DM) patients in Bali, Indonesia.

CONCLUSION

Polymorphism of VEGF-2578C/A (rs699947) allele distribution can be concluded as a risk factor of DR within T2DM patients in Bali, Indonesia. This study may also be used to expand the knowledge in managing DR patients at an earlier stage to avoid further complications.

Endometrial angiogenesis induced by uterine insufflation with an oxygen-ozone gas mixture in mares

Ozone (O₃ ) therapy has been used to improve peripheral tissue oxygenation in humans and domestic animals. The goal of the present study was to characterize histological changes in the endometria of healthy equines following tissue exposure to gas mixtures enriched with different concentrations of O₃ . Cycling mares without endometrial degeneration were divided into three groups according to treatment (n = 9 mares/group). The uteri from the O₃ , ½O₃ and control groups were insufflated for 3 min with gas containing 42, 21 and 0 μg O₃ ml^-1 , respectively. Treatments were performed every three days from D0 to D6. Endometrial samples were collected immediately before the first treatment and 24 hr after the last treatment. The following nine histological parameters were evaluated: (i) the number of endometrial blood vessels, (ii) endometrial vascular degree (EVD), (iii) increase rate of blood vessels, (iv) increase rate of EVD, (v) glandular total area, (vi) glandular lumen area, (vii) intraglandular secretion area, (viii) glandular epithelial height and (ix) luminal epithelial height. In the O₃ group, a positive effect from treatment (p < .01) was detected for all vascular parameters (i, ii, iii and iv), glandular total area, intraglandular secretion area and glandular epithelial height. Compared to the control group, the ½O₃ group had greater (p < .01) EVD (84.1 ± 12%) and a higher increase rate of blood vessels (151.9 ± 47.1%). Uterine insufflation with low or intermediate concentrations of the O₂ -O₃ gas mixture induced endometrial angiogenesis. Morphometry, but not morphology, of the endometrial glands was affected by local O₃ therapy. These findings would be of great significance for the development of new therapies for infertility in mares.

DNA methylation profiling of CD04+/CD08+ T cells reveals pathogenic mechanisms in increasing hyperglycemia: PIRAMIDE pilot study

Background

DNA methylation can play a pathogenic role in the early stages of hyperglycemia linking homeostasis imbalance and vascular damage.

Material and methods

We investigated DNA methylome by RRBS in CD04⁺ and CD08⁺ T cells from healthy subjects (HS) to pre-diabetics (Pre-Diab) and type 2 diabetic (T2D) patients to identify early biomarkers of glucose impairment and vascular damage. Our cross-sectional study enrolled 14 individuals from HS state to increasing hyperglycemia (pilot study, PIRAMIDE trial, NCT03792607).

Results

Globally, differentially methylated regions (DMRs) were mostly annotated to promoter regions. Hypermethylated DMRs were greater than hypomethylated in CD04⁺ T cells whereas CD08⁺ T showed an opposite trend. Moreover, DMRs overlapping between Pre-Diab and T2D patients were mostly hypermethylated in both T cells. Interestingly, SPARC was the most hypomethylated gene in Pre-Diab and its methylation level gradually decreased in T2D patients. Besides, SPARC showed a significant positive correlation with DBP (+0.76), HDL (+0.54), Creatinine (+0.83), LVDd (+0.98), LVSD (+0.98), LAD (+0.98), LVPWd (+0.84), AODd (+0.81), HR (+0.72), Triglycerides (+0.83), LAD (+0.69) and AODd (+0.52) whereas a negative correlation with Cholesterol (−0.52) and LDL (−0.71) in T2D.

Conclusion

SPARC hypomethylation in CD08⁺ T cells may be a useful biomarker of vascular complications in Pre-Diab with a possible role for primary prevention warranting further multicenter clinical trials to validate our findings.

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We conducted the first methylome analysis by RRBS platform in circulating CD04⁺ and CD08⁺ T cells in increasing hyperglycemia.

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This approach has revealed possible biomarkers for cardiovascular and kidney complications in prediabetes.

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SPARC hypomethylation may underly a pro-fibrotic endophenotype to be validated in larger multicenter trials.

Topical ozonated virgin coconut oil improves wound healing and increases HSP90α, VEGF-A, EGF, bFGF and CD34 in diabetic ulcer mouse model of wound healing

Background: Diabetes is a disease that affects people worldwide, including in Indonesia. The prevalence of diabetes in Indonesia is increasing from year to year. One of the most devastating complications of diabetes mellitus is diabetic ulcers, which is a limb-threatening complication. Over the past few decades, ozone generated using plasma medical technology has been investigated as an agent that helps wound healing. This study aims to evaluate the effects of topical ozonated virgin coconut oil (VCO) in a diabetic wound mouse model. Methods: This study was an experimental study with a post-test control design. An ulcer wound model was made in 50 diabetic male Wistar mice, divided into five groups, and a control group of 10 non-diabetic mice. The control groups were given conventional therapy only and the treatment groups were also given topical ozonated VCO with different flow durations (0 min, 90 min, 7 h, 14 h). Macroscopic appearance and wound contraction were observed. HSP90β, VEGF-A, EGF, bFGF and CD34 levels were measured from the immunostained slices of wound margins. Results: The reduction of wound length was proportionally related to the duration of ozone flow. Ozonated VCO with a longer duration of ozone flow healed the wound more quickly and had the shortest wound length. VCO with ozone flow for 14 hours (16837.10 µm) had the biggest reduction in wound length compared to other groups. The wounds treated with ozonated VCO showed an increase in HSP90β, VEGF-A, EGF, bFGF and CD34 levels that correlated to improved wound healing. A longer period of treatment resulted in higher levels of wound healing biomarkers compared to shorter therapeutic durations. Conclusions: Topical ozonated VCO improved the wound healing process in a diabetic ulcer mouse model by improving macroscopic wound appearance and increasing levels of wound healing biomarkers.

Aflibercept regulates retinal inflammation elicited by high glucose via the PlGF/ERK pathway

Diabetic retinopathy (DR) is a secondary complication of diabetes. DR can cause irreversible blindness, and its pathogenesis is considered multifactorial. DR can progress from non-proliferative DR to proliferative DR, characterized by retinal neovascularization. The main cause of vision loss in diabetic patients is diabetic macular edema, caused by vessel leakage and blood retinal barrier breakdown. Currently, aflibercept is an anti-VEGF approved for diabetic macular edema. Aflibercept can bind several members of vascular permeability factors, namely VEGF-A, B, and PlGF. We analyzed the aflibercept-PlGF complex at molecular level, through an in silico approach. In order to explore the role of PlGF in DR, we treated primary human retinal endothelial cells (HRECs) and mouse retinal epithelial cells (RPEs) with aflibercept and an anti-PlGF antibody. We explored the hypothesis that aflibercept has anti-inflammatory action through blocking of PlGF signaling and the ERK axis in an in vitro and in vivo model of DR. Both aflibercept and the anti-PlGF antibody exerted protective effects on retinal cells, by inhibition of the ERK pathway. Moreover, aflibercept significantly decreased (p < 0.05) the expression of TNF-α in an in vitro and in vivo model of DR. Therefore, our data suggest that inhibition of PlGF signaling, or a selective blocking, may be useful in the management of early phases of DR when the inflammatory process is largely involved.

High glucose conditioned neonatal astrocytes results in impaired mitogenic activity in cerebral microvessel endothelial cells in co-culture

Angiogenesis is a highly complex and coordinated process in the brain. Under normal conditions, it is a vital process in growth and development, but under adverse conditions such as diabetes mellitus, it can lead to severe pathology. Astrocytes are a key constituent of the neurovascular unit and contribute to cerebral function, not only bridging the gap between metabolic supplies from blood vessels to neurons, but also regulating angiogenesis. Astrocytes affect angiogenesis by secreting angiogenic factors such as vascular endothelial growth factor (VEGF) into its microenvironment and regulating mitogenic activity in cerebral microvessel endothelial cells (CMEC). We hypothesized that astrocytes conditioned in high glucose media would produce and secrete decreased VEGF which would lead to impaired proliferation, migration, and tube formation of CMEC in vitro. Using neonatal rat astrocytes, we used normal glucose (NG, 5.5mM) vs. high glucose (HG, 25mM) feeding media and measured VEGF message and protein levels as well as secreted VEGF. We co-cultured conditioned astrocytes with isolated rat CMEC and measured mitogenic activity of endothelial cells using BrdU assay, scratch recovery assay, and tube formation assay. HG astrocytes produced and secreted decreased VEGF protein and resulted in impaired mitogenic activity when co-cultured with CMEC as demonstrated by decreased BrdU uptake, decreased scratch recovery, and slower tube formation. Our study provides insight into gliovascular adaptations to increased glucose levels resulting in impaired cellular cross-talk between astrocytes and CMEC which could be one explanation for cerebral microangiopathy seen in diabetic conditions.

Pericytes in Breast Cancer

Breast cancer is a heterogeneous disease driven not only by evolutionally diverse cancer cell themselves but also by highly dynamic microenvironment. At the center of the tumor microenvironment, tumor vasculature plays multiple roles from supporting tumor growth to providing a route for metastasis to the distant organ sites. Blood vessels in breast cancer present with perfusion defects associated with vessel dilation, tortuosity, and poor perivascular coverage (Li et al., Ultrasound Med 32:1145-1155, 2013; Eberhard et al., Cancer Res 60:1388-1393, 2000; Cooke et al., Cancer Cell 21:66-81, 2012). Such abnormal vascular system is partly due to the morphological and molecular alteration of pericytes that is accompanied by a significant heterogeneity within the populations (Kim et al., JCI Insight 1:e90733, 2016). While pericytes are implicated for their controversial roles in breast cancer metastasis (Cooke et al., Cancer Cell 21:66-81, 2012; Gerhardt and Semb, J Mol Med (Berl) 86:135-144, 2008; Keskin et al., Cell Rep 10:1066-1081, 2015; Meng et al., Future Oncol 11:169-179, 2015; Xian et al., J Clin Invest 116:642-651, 2006), the impact of their heterogeneity on breast cancer progression, metastasis, intratumoral immunity, and response to chemotherapy are largely unknown. Due to the complexity of angiogenic programs of breast cancer, the anti-angiogenic or anti-vascular treatment has been mostly unsuccessful (Tolaney et al., Proc Natl Acad Sci U S A 112:14325-14330, 2015; Mackey et al., Cancer Treat Rev 38:673-688, 2012; Sledge, J Clin Oncol 33:133-135, 2015) and requires much in-depth knowledge on different components of tumor microenvironment and how these stromal cells are interacting and communicating to each other. Therefore, understanding pericyte heterogeneity and their differential functional contribution will shed light on new potential approaches to treat breast cancer.

The association between cigarette smoking and diabetic nephropathy in Chinese male patients

AIMS

To investigate the association between cigarette smoking and the clinicopathological features and renal prognosis of type 2 diabetic mellitus (T2DM) patients with diabetic nephropathy (DN).

METHODS

A total of 223 T2DM male patients with biopsy-proven DN who received follow-up for at least 1 year were recruited. The patients were divided into two groups based on smoking status: smoking group and non-smoking group. Clinicopathologic differences were analyzed between the two groups. In addition, smokers were divided into two groups of binary analysis based on smoking amounts and two groups of former smokers and current smokers, and subgroups analysis based on age and DR, respectively. The influence of smoking on estimated glomerular filtration rate (eGFR) was estimated using logistic regression analysis and Cox regression on renal outcomes. Renal outcomes were defined by progression to end-stage renal disease (ESRD) or doubling of serum creatinine (D-SCr) level.

RESULTS

Compared with nonsmokers, smoking patients had more moderate decline eGFR (p = 0.032) and tubular atrophy and interstitial fibrosis (p = 0.033). The adjusted logistic regression analysis suggested cigarette smoking was negatively associated with more severe decline eGFR (p = 0.015), especially for patients with DR (p = 0.010) and patients of age ≤ 50 years (p = 0.012) in the subgroup analysis. In the prognosis analysis, no obvious significant risk factor was shown about smoking. Interestingly, it was observed that former smokers had lower levels of plasma glucose and triglycerides than current smokers (both p < 0.05), while smokers with small smoking amounts had lower levels of triglycerides than those with large smoking amounts (p < 0.05).

CONCLUSION

Cigarette smoking patients with T2DM and DN had more moderate decline eGFR, especially for DN patients with DR, and milder IFTA lesions, although an obviously significant risk factor was not shown about smoking for DN.

Single Cell Analysis Identifies the miRNA Expression Profile of a Subpopulation of Muscle Precursor Cells Unique to Humans With Type 2 Diabetes

MicroRNAs (miRNAs) take part in regulating central cellular processes such as differentiation and metabolism. We have previously shown that muscle progenitor cells derived from individuals with type 2 diabetes (T2DM) have a dysregulated miRNA profile. We hypothesized that the T2DM muscle progenitor population is heterogeneous in its miRNA expression and differs from the progenitor population of healthy controls. MiRNA expression profiles of CD56+ muscle progenitor cells from people with T2DM and from healthy controls were therefore investigated at a single cell level. Single-cell analysis revealed three subpopulations expressing distinct miRNA profiles: two subpopulations including both T2DM and healthy control muscle precursors presented miRNA expression profiles mostly overlapping between groups. A distinct third subpopulation consisted solely of cells from donors with T2DM and showed enriched expression of miRNAs previously shown to be associated with type 2 diabetes. Among the enriched miRNAs was miR-29, a regulator of GLUT4 mRNA expression. Interestingly, this subpopulation also revealed several miRNAs with predicted targets in the PI3K/Akt pathway, not previously described in relation to T2DM muscle dysfunction. We concluded that a subpopulation of T2DM muscle precursor cells is severely dysregulated in terms of their miRNA expression, and accumulation of this population might thus contribute to the dysfunctional muscular phenotype in type 2 diabetes.

ANRIL regulates production of extracellular matrix proteins and vasoactive factors in diabetic complications

noncoding RNAs (lncRNAs) have gained widespread interest due to their prevailing presence in various diseases. lncRNA ANRIL (a. k. a. CDKN2B-AS1) is located on human chromosome 9 (p21.3) and transcribed in opposite direction to the INK4b-ARF-INK4a gene cluster. It has been identified as a highly susceptible region for diseases such as coronary artery diseases and type 2 diabetes. Here, we explored its regulatory role in diabetic nephropathy (DN) and diabetic cardiomyopathy (DCM) in association with epigenetic modifiers p300 and polycomb repressive complex 2 (PRC2) complex. We used an ANRIL-knockout (ANRILKO) mouse model for this study. The wild-type and ANRILKO animals with or without streptozotocin-induced diabetes were monitored for 2 min. At the end of the time point, urine and tissues were collected. The tissues were measured for fibronectin (FN), type IV collagen (Col1α4), and VEGF mRNA and protein expressions. Renal function was determined by the measurement of 24-h urine volume and albumin/creatinine ratio at euthanasia. Renal and cardiac structures were investigated using periodic acid-Schiff stain and/or immunohistochemical analysis. Elevated expressions of extracellular matrix (ECM) proteins were prevented in ANRILKO diabetic animals. Furthermore, ANRILKO had a protective effect on diabetic mouse kidneys, as evidenced by lowering of urine volume and urine albumin levels in comparison with the wild-type diabetic animals. These alterations regulated by ANRIL may be mediated by p300 and enhancer of zeste 2 (EZH2) of the PRC2 complex. Our study concludes that ANRIL regulates functional and structural alterations in the kidneys and hearts in diabetes through controlling the expressions of ECM proteins and VEGF.

Diabetes mellitus and risk of ovarian cancer. A systematic review and meta-analysis of 15 cohort studies

AIM

Diabetes mellitus (DM) is hypothesized to be associated with an increased risk of ovarian cancer (OC), but current evidences are inconsistent. We aimed to further study this association.

METHODS

PubMed, EMBASE, Web of Science, and Scopus were searched for eligible articles. After descriptive summary of the data, a random-effects model was applied in quantitative synthesis. Subgroup analysis was performed by study locales and settings, and sensitivity analysis was conducted based on restrictive selection criteria. Funnel plots and the Egger's test were used to assess publication bias. Statistical heterogeneity in meta-analysis was assessed by the P value derived from the Cochrane Q statistic and I-squared value.

RESULTS

Fourteen articles involving data of 15 cohort studies were included for our research. Overall, 17 risk ratios (RRs) were synthesized and yielded a pooled RR of 1.32 (95%CI: 1.14-1.52, P_Cochrane<0.001, I²=79.8%). Thirteen RRs were synthesized for type 2DM, and the pooled RR was 1.24 (95%CI: 1.06-1.44, P_Cochrane<0.001, I²=81.8%). Four RRs were synthesized for type 1DM, and the result was significant (RR: 1.83, 95%CI: 1.21-2.78, P_Cochrane=0.080, I²=55.7%). Results of sensitivity analysis suggested the robustness of a positive association between DM and OC risk, and subgroup analysis demonstrated that the association between DM and OC was much more substantial among Asia population. No publication bias was identified in meta-analysis.

CONCLUSION

Our study suggests there is a moderate relative increase in the risk of OC among DM patients. Future studies should investigate the effect of duration of DM and anti-diabetes intervention to OC risk.

Diabetes mellitus and long-term mortality of ovarian cancer patients. A systematic review and meta-analysis of 12 cohort studies

Ovarian cancer (OC) is the sixth most common cancer among women, and its prognosis is not favorable. Diabetes mellitus (DM) is hypothesized to be associated with a higher mortality in ovarian cancer patients, but evidence is inconsistent. Thus, we aim to investigate if DM is associated with the long-term all-cause and long-term cancer-specific mortality in ovarian cancer patients by synthesizing available epidemiologic evidences. We used 4 electronic databases (PubMed, EMBASE, Web of Science, and Scopus) to search for eligible articles. Title/abstract screening, full-text review, data extraction, and quality assessment were performed by reviewers independently. In meta-analysis, studies reporting risk ratio (RR) or hazard ratio that investigated the association between DM and mortality of OC patients were synthesized by a random-effect model. Subgroup and sensitivity analyses were performed by certain stratification or restrictive rules. Publication bias was assessed by funnel plots and Egger test. Statistical heterogeneity was evaluated by the I-squared value and a chi-squared test for the Cochrane Q statistic. Twelve cohort studies involving 14 outcome measures were included. In overall meta-analysis, the synthesized RR for all-cause mortality was 1.44 (95% CI 1.16-1.79) without substantial statistical heterogeneity (P_Cochrane  = .145, I²  = 34.1%); the synthesized RR for cancer-specific mortality was 1.44 (95% CI 1.08-1.93) with substantial heterogeneity (P_Cochrane  < .001, I²  = 90.1%). No publication bias was observed. Our results suggest DM is associated with a higher all-cause and cancer-specific mortality in ovarian cancer patients. Future studies should be done to examine the association between type 1 DM and ovarian cancer mortality.

TGFβ induces BIGH3 expression and human retinal pericyte apoptosis: a novel pathway of diabetic retinopathy

PurposeOne of the earliest hallmarks of diabetic retinopathy is the loss of retinal pericytes. However, the mechanisms that promote pericyte dropout are unknown. In the present study, we propose a novel pathway in which pericyte apoptosis is mediated by macrophages, TGFβ and pro-apoptotic BIGH3 (TGFβ-induced Gene Human Clone 3) protein.Patients and methodsTo elucidate this pathway, we assayed human retinal pericyte (HRP) apoptosis by TUNEL assay, BIGH3 mRNA expression by qPCR, and BIGH3 protein expression by western blot analysis. HRP were treated with BIGH3 protein, TGFβ1 and TGFβ2 and inhibition assays were carried out by blocking with antibodies against BIGH3. The distribution of BIGH3 and CD68⁺ macrophages were compared in a post-mortem donor eye with 7-year history of Type II diabetes and histopathogically confirmed non-proliferative diabetic retinopathy (NPDR).ResultsTGFβ induced a significant increase in BIGH3 mRNA and protein expression, and HRP apoptosis. BIGH3 treatment showed HRP undergo apoptosis in a dose-dependent manner. At 5 μg/ml, BIGH3 induced 3.5-times more apoptosis in HRP than in retinal endothelial cells. TGFβ induced apoptosis was inhibited by blocking with antibodies against BIGH3. In an example of NPDR, BIGH3 accumulated within the walls of the inner retina arterioles. Macrophage infiltrates were frequently associated with these vessels and the inner nuclear layer.ConclusionTogether with our previously published results on macrophage-induced retinal endothelial cell apoptosis, the present study supports a novel inflammatory pathway mediated by macrophages and the BIGH3 protein leading to HRP apoptosis. As shown in human post-mortem globes, these observations are clinically relevant, suggesting a new mechanism underlying pericyte dropout during NPDR.

Directing an artificial zinc finger protein to new targets by fusion to a non-DNA-binding domain

Transcription factors are often regarded as having two separable components: a DNA-binding domain (DBD) and a functional domain (FD), with the DBD thought to determine target gene recognition. While this holds true for DNA binding in vitro, it appears that in vivo FDs can also influence genomic targeting. We fused the FD from the well-characterized transcription factor Krüppel-like Factor 3 (KLF3) to an artificial zinc finger (AZF) protein originally designed to target the Vascular Endothelial Growth Factor-A (VEGF-A) gene promoter. We compared genome-wide occupancy of the KLF3FD-AZF fusion to that observed with AZF. AZF bound to the VEGF-A promoter as predicted, but was also found to occupy approximately 25 000 other sites, a large number of which contained the expected AZF recognition sequence, GCTGGGGGC. Interestingly, addition of the KLF3 FD re-distributes the fusion protein to new sites, with total DNA occupancy detected at around 50 000 sites. A portion of these sites correspond to known KLF3-bound regions, while others contained sequences similar but not identical to the expected AZF recognition sequence. These results show that FDs can influence and may be useful in directing AZF DNA-binding proteins to specific targets and provide insights into how natural transcription factors operate.

Alpha-lipoic acid modifies circulating angiogenic factors in patients with type 2 diabetes mellitus

AIMS

In recent years interest has been focused on angiogenesis as a process involved in coronary artery disease (CAD) and diabetic distal sensorimotor polyneuropathy (DSPN). Recent studies have demonstrated the possible angiogenesis-modulating potential of alpha-lipoic acid (ALA) for DSPN and CAD. The aim of our study was to investigate the influence of ALA on serum angiogenic factors in patients with DM-2 (type 2 diabetes) with CAD and DSPN.

METHODS

Sixty patients with type 2 DM (T2DM) and CAD and 25 non-diabetic subjects were studied. Thirty patients with T2DM, CAD and DSPN were given 600 mg of ALA a day for 90 days. VEGF, bFGF, MCP-1, angiogenin, IL-12 and IL-10 concentrations in the sera were measured by flow cytometry.

RESULTS

ALA significantly increased VEGF, bFGF and IL-10 and decreased MCP-1 serum concentrations in patients with T2DM and CAD and DSPN. VEGF and IL-10 serum levels, both before and after ALA-treatment, were higher in this group than in T2DM and CAD patients, while circulating bFGF was higher and MCP-1 serum level lower in patients with T2DM and CAD and DSPN only in the post-ALA-treatment, compared to the T2DM and CAD group.

CONCLUSIONS

ALA may influence angiogenesis in type 2 diabetic patients through an effect on some circulating factors including VEGF, bFGF, MCP-1 and IL-10.

Circulating monocyte chemotactic protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1) and angiogenin in type 2 diabetic patients treated with statins in low doses

Statins are known as agents promoting a biphasic dose-dependent effect on angiogenesis under experimental conditions. Dysregulation of angiogenesis plays an important role in the development of atherosclerosis and it may be affected by metabolic factors. The aim of this research was to explain how low doses of statins modify serum concentrations of pro-angiogenic factors MCP-1 and angiogenin in type 2 diabetic patients. Measurements of metabolic control parameters were performed in 30 patients with type 2 diabetes treated with low doses of statin, and in 34 statin-free patients with type 2 diabetes. The serum levels of MCP-1 and VCAM-1 in statin-treated patients were lower than those of the statin-free group. ANCOVA results revealed that these effects were dependent only on the use of statins. In type 2 diabetic subjects, overall positive correlation was found between total cholesterol or LDL serum concentration and MCP-1 serum level. The angiogenin concentration in the serum did not show differences and was comparable in both groups. The angiogenin serum level correlated negatively with HDL, LDL and with HbA1c. Multivariate regression analysis indicated that angiogenin serum levels in type 2 diabetic patients were determined mainly by HbA1c, HDL-cholesterol and diabetes duration. It has been shown that statins used in low doses in type 2 diabetic subjects decrease MCP-1 and VCAM-1serum levels, most likely due to the statins-related effect on the lipid profile, while angiogenin serum levels in this group are determined rather by the current metabolic control.

IVS1 -397T>C estrogen receptor α polymorphism is associated with low-grade systemic inflammatory response in type 1 diabetic girls

PURPOSE

The study aimed to investigate the influence of estrogen receptor α (ER-α) genotypes on inflammatory response and development of microvascular complications in girls with type 1 diabetes.

METHODS

152 young regularly menstruating girls with diagnosed type 1 diabetes and 84 young, healthy menstruating girls were recruited. ER-α genotyping was carried out by PCR. Serum concentrations of 17β-estradiol, as well as IL-6, TNF-α, VEGF, and IL-10, were measured. CD4(+)Foxp3(+) TH17 cells were isolated and analyzed by flow cytometry.

RESULTS

Type 1 diabetic girls carrying TT genotype were characterized by the lowest serum estradiol level and IL-10 and highest IL-6, TNF-α, and VEGF. The association between the level of certain cytokine and the genetic variant of estrogen receptor α polymorphism was analyzed. Frequencies of CD4(+)Foxp3(+) TH17 cells were also enhanced in TT bearing girls with type 1 diabetes and correlated with the level of analyzed cytokines. In addition, the correlation between serum estradiol level and cytokine concentrations was observed.

CONCLUSIONS

We propose that TT variant of estrogen receptor α polymorphism may be associated with enhanced inflammatory response, which in turn may lead to acceleration of diabetic retino- and nephropathy in girls with type 1 diabetes. This finding may help the physicians to predict the onset and progression of diabetic microvascular complications.

Pericytes from infantile hemangioma display proangiogenic properties and dysregulated angiopoietin-1

OBJECTIVE

Infantile hemangioma (IH) is a rapidly growing vascular tumor affecting newborns. It is composed of immature endothelial cells and pericytes that proliferate into a disorganized mass of blood vessels. We isolated pericytes from IH (Hem-pericytes) to test our hypothesis that Hem-pericytes are unable to stabilize blood vessels.

METHODS AND RESULTS

We injected pericytes in vivo, in combination with endothelial cells, and found that Hem-pericytes formed more microvessels compared with control retinal pericytes. We, thereby, analyzed proangiogenic properties of the Hem-pericytes. They grew fast in vitro, and were unable to stabilize endothelial cell growth and migration, and expressed high levels of vascular endothelial growth factor-A compared with retinal pericytes. Hem-pericytes from proliferating phase IH showed lower contractility in vitro, compared with Hem-pericytes from the involuting phase and retinal pericytes. Consistent with a diminished ability to stabilize endothelium, angiopoietin 1 was reduced in Hem-pericytes compared with retinal pericytes. Normal retinal pericytes in which angiopoietin 1 was silenced produced conditioned medium that stimulated endothelial cell proliferation and migration.

CONCLUSIONS

We report the first successful isolation of patient-derived pericytes from IH tissue. Hem-pericytes exhibited proangiogenic properties and low levels of angiopoietin 1, consistent with a diminished ability to stabilize blood vessels in IH.

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) enhances engraftment and angiogenesis of mesenchymal stem cells in diabetic hindlimb ischemia

To examine whether the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a key regulator linking angiogenesis and metabolism, could enhance the engraftment and angiogenesis of mesenchymal stem cells (MSCs) in diabetic hindlimb ischemia, we engineered the overexpression of PGC-1α within MSCs using an adenoviral vector encoding green fluorescent protein and PGC-1α, and then tested the survivability and angiogenesis of MSCs in vitro and in vivo. Under the condition of hypoxia concomitant with serum deprivation, the overexpression of PGC-1α in MSCs resulted in a higher expression level of hypoxia-inducible factor-1α (Hif-1α), a greater ratio of B-cell lymphoma leukemia-2 (Bcl-2)/Bcl-2-associated X protein (Bax), and a lower level of caspase 3 compared with the controls, followed by an increased survival rate and an elevated expression level of several proangiogenic factors. In vivo, the MSCs modified with PGC-1α could significantly increase the blood perfusion and capillary density of ischemic hindlimb of the diabetic rats, which was correlated to an improved survivability of MSCs and an increased level of several proangiogenic factors secreted by MSCs. We identified for the first time that PGC-1α could enhance the engraftment and angiogenesis of MSCs in diabetic hindlimb ischemia.

Vitreous vascular endothelial growth factor concentrations in proliferative diabetic retinopathy versus proliferative vitreoretinopathy

PURPOSE

To assess vitreous vascular endothelial growth factor (VEGF) concentrations in proliferative diabetic retinopathy (PDR) in comparison to proliferative vitreoretinopathy (PVR).

PATIENTS AND METHODS

Vitreous samples were collected from 69 eyes of 69 patients with traumatic lens dislocation (n = 10), grade B PVR with rhegmatogenous retinal detachment (n = 13), grade C PVR with rhegmatogenous retinal detachment (n = 14), PDR with vitreous hemorrhage (n = 18), and PDR with vitreous hemorrhage and tractional retinal detachment (n = 14). Vitreous fluid samples were obtained at vitrectomy, and the levels of VEGF were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean vitreous level of VEGF was 15.14 ± 5.22 pg/ml in eyes with grade B PVR, 99.15 ± 38.58 pg/ml in eyes with grade C PVR, 4,534.01 ± 1,193.28 pg/ml in eyes with vitreous hemorrhage secondary to PDR, 5,157.29 ± 969.44 pg/ml in eyes with vitreous hemorrhage and tractional retinal detachment secondary to PDR, and 16.19 ± 5.76 pg/ml in eyes of the control group with traumatic lens dislocation. Vitreous VEGF concentrations were significantly higher in the patients with grade C PVR, PDR with vitreous hemorrhage and PDR with vitreous hemorrhage and tractional retinal detachment in comparison to the control patients (p < 0.05). A significant alteration was not observed in patients with grade B PVR (p = 0.55).

CONCLUSIONS

Vitreous VEGF concentrations are increased in PDR and grade C PVR. The high VEGF concentrations could suggest a possible effect of VEGF on advanced PVR.

The role of dysregulated glucose metabolism in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic cancer and also one of the most poorly understood. Other health issues that are affecting women with increasing frequency are obesity and diabetes, which are associated with dysglycemia and increased blood glucose. The Warburg Effect describes the ability of fast-growing cancer cells to preferentially metabolize glucose via anaerobic glycolysis rather than oxidative phosphorylation. Recent epidemiological studies have suggested a role for hyperglycemia in the pathogenesis of a number of cancers. If hyperglycemia contributes to tumour growth and progression, then it is intuitive that antihyperglycemic drugs may also have an important antitumour role. Preliminary reports suggest that these drugs not only reduce available plasma glucose, but also have direct effects on cancer cell viability through modification of molecular energy-sensing pathways. This review investigates the effect that hyperglycemia may have on EOC and the potential of antihyperglycemic drugs as therapeutic adjuncts.

Poor functional recovery after transplantation of diabetic bone marrow stem cells in ischemic myocardium

BACKGROUND

Autologous bone marrow mononuclear cell (BMMC) therapy has shown promise for improving cardiac function after myocardial infarction. The efficiency of such therapy for diabetic patients remains unknown.

METHODS

BMMCs were harvested from type 2 diabetic male BKS.Cg-m+/+Lepr(db)/J mice or C57BLKS/J (non-diabetic control) mice and were isolated using Ficoll-based separation. Cell characterization was performed by flow cytometry. Cell viability was determined by apoptosis and proliferation assays. Female BKS.Cg-m+/+Lepr(db)/J mice underwent left anterior descending artery ligation and were randomized into 3 groups receiving 2.5 x 10(6) diabetic BMMCs (n = 8), 2.5 x 10(6) control BMMCs (n = 8), or phosphate-buffered saline (n = 6). At Week 5, cardiac function was assessed with echocardiography and invasive hemodynamic measurements. Post-mortem cell survival was quantified by TaqMan real-time transcription polymerase chain reaction (RT-PCR) for the male Sry gene.

RESULTS

BKS.Cg-m+/+Lepr(db)/J BMMCs showed a significantly lower mononuclear fraction and a significantly lower proliferation rate compared with C57BLKS/J BMMCs. Fractional shorting (40.1% +/- 1.2% vs 30.3% +/- 1.9%; p = 0.001) and cardiac output (4,166 +/- 393 vs 2,246 +/- 462 microl/min; p = 0.016) significantly improved for mice treated with control BMMCs injection compared with those treated with diabetic BMMCs, respectively. This difference could not be attributed to difference in cell engraftment because TaqMan RT-PCR showed no significant difference in cell survival in infarcted hearts between the 2 groups.

CONCLUSIONS

Diabetic BMMCs are significantly impaired in their ability to improve cardiac function after myocardial infarction compared with control BMMCs. These findings could have significant clinical implication regarding autologous BMMC therapy in diabetic patients.

Role of parathyroid hormone-related protein in the decreased osteoblast function in diabetes-related osteopenia

A deficit in bone formation is a major factor in diabetes-related osteopenia. We examined here whether diabetes-associated changes in osteoblast phenotype might in part result from a decrease in PTH-related protein (PTHrP). We used a bone marrow ablation model in diabetic mice by multiple streptozotocin injections. PTHrP (1-36) (100 microg/kg, every other day) or vehicle was administered to mice for 13 d starting 1 wk before marrow ablation. Diabetic mice showed bone loss in both the intact femur and the regenerating tibia on d 6 after ablation; in the latter, this was related to decreased bone-forming cells, osteoid surface, and blood vessels, and increased marrow adiposity. Moreover, a decrease in matrix mineralization occurred in ex vivo bone marrow cultures from the unablated tibia from diabetic mice. These skeletal alterations were associated with decreased gene expression (by real-time PCR) of Runx2, osterix, osteocalcin, PTHrP, the PTH type 1 receptor, vascular endothelial growth factor and its receptors, and osteoprotegerin to receptor activator of nuclear factor-kappaB ligand mRNA ratio, and increased peroxisome proliferator-activated receptor-gamma2 mRNA levels. Similar changes were induced by hyperosmotic (high glucose or mannitol) medium in osteoblastic MC3T3-E1 cells, which were mimicked by adding a neutralizing anti-PTHrP antibody or PTH type 1 receptor antagonists to these cells in normal glucose medium. PTHrP (1-36) administration reversed these changes in both intact and regenerating bones from diabetic mice in vivo, and in MC3T3-E1 cells exposed to high glucose. These findings strongly suggest that PTHrP has an important role in the altered osteoblastic function related to diabetes.

FOXO1 plays an important role in enhanced microvascular cell apoptosis and microvascular cell loss in type 1 and type 2 diabetic rats

OBJECTIVE

To investigate early events leading to microvascular cell loss in diabetic retinopathy.

RESEARCH DESIGN AND METHODS

FOXO1 was tested in vivo by DNA binding activity and by nuclear translocation in microvascular cells in retinal trypsin digests. In vivo studies were undertaken in STZ-induced diabetic rats and Zucker diabetic fatty rats using the tumor necrosis factor (TNF)-specific blocker, pegsunercept, or by inhibiting FOXO1 with RNAi. Microvascular cell apoptosis, formation of pericyte ghosts, and acellular capillaries were measured. Upstream and downstream effects of high-glucose-induced FOXO1 were tested on rat microvascular endothelial cells (RMECs) by small-interfering RNA (siRNA) in vitro.

RESULTS

DNA binding or nuclear translocation of FOXO1, which was reduced by TNF inhibition, was elevated in type 1 and type 2 diabetic retinas. Diabetes stimulated microvascular cell apoptosis; pericyte ghost and acellular capillary development was inhibited by FOXO1 siRNA. High glucose in vitro decreased FOXO1 phosphorylation and DNA binding activity and decreased Akt phosphorylation in RMECs. High-glucose-stimulated FOXO1 DNA binding activity was mediated through TNF-alpha and formation of reactive oxygen species (ROS), while inhibitors of TNF and ROS and FOXO1 siRNA reduced high-glucose-enhanced RMEC apoptosis. The caspase-3/7 activity and capacity of high glucose to increase mRNA levels of several genes that regulate RMEC activation and apoptosis were knocked down by FOXO1 siRNA.

CONCLUSIONS

FOXO1 plays an important role in rat retinal microvascular cell loss in type 1 and type 2 diabetic rats and can be linked to the effect of high glucose on FOXO1 activation.

The role of vascular endothelial growth factor, tumor necrosis factor alpha and interleukin-6 in pathogenesis of diabetic retinopathy

The aim of the study was to analyze the relation between early diabetic retinopathy and the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF) in children with diabetes mellitus type 1. Two hundred and two children with diabetes mellitus type 1 aged 13.2+/-3.83 years and 85 healthy controls were analyzed. Patients were divided into two subgroups: children with retinopathy (Group 1, n=39) and children without retinopathy (Group 2, n=163). All the children had 24h urine albumin secretion rate, glycosylated hemoglobin HbA1c level, and C-reactive protein level measured, underwent 24h blood pressure monitoring and had ophthalmologic examination performed. Additionally, all the children had serum TNF-alpha, IL-6 and VEGF level measured using an ELISA test (Quantikine High Sensitivity Human). Statistically significant higher blood serum levels of HbA1c, VEGF, TNF-alpha and IL-6 were found in the Group 1 in comparison with the Group 2. Additionally, the children of the Group 1 showed statistically significant correlation between serum VEGF and serum TNF-alpha (R=0.35, p=0.000), CRP level (R=0.23, p=0.006), 24h albumin urine secretion rate (R=0.45, p=0.000) and duration of the disease (R=0.26, p=0.002). The results of the current study suggest that there is a relationship between VEGF, TNF-alpha, IL-6 and the development of the diabetic retinopathy in children with diabetes mellitus type 1.

The role of pericytes in blood-vessel formation and maintenance

Blood vessels are composed of two interacting cell types. Endothelial cells form the inner lining of the vessel wall, and perivascular cells--referred to as pericytes, vascular smooth muscle cells or mural cells--envelop the surface of the vascular tube. Over the last decades, studies of blood vessels have concentrated mainly on the endothelial cell component, especially when the first angiogenic factors were discovered, while the interest in pericytes has lagged behind. Pericytes are, however, functionally significant; when vessels lose pericytes, they become hemorrhagic and hyperdilated, which leads to conditions such as edema, diabetic retinopathy, and even embryonic lethality. Recently, pericytes have gained new attention as functional and critical contributors to tumor angiogenesis and therefore as potential new targets for antiangiogenic therapies. Pericytes are complex. Their ontogeny is not completely understood, and they perform various functions throughout the body. This review article describes the current knowledge about the nature of pericytes and their functions during vessel growth, vessel maintenance, and pathological angiogenesis.

Vascular complications in diabetes mellitus: the role of endothelial dysfunction

The endothelium is a complex organ with a multitude of properties essential for control of vascular functions. Dysfunction of the vascular endothelium is regarded as an important factor in the pathogenesis of diabetic micro- and macro-angiopathy. Endothelial dysfunction in Type I and II diabetes complicated by micro- or macro-albuminuria is generalized in that it affects many aspects of endothelial function and occurs not only in the kidney. The close linkage between microalbuminuria and endothelial dysfunction in diabetes is an attractive explanation for the fact that microalbuminuria is a risk marker for atherothrombosis. In Type I diabetes, endothelial dysfunction precedes and may cause diabetic microangiopathy, but it is not clear whether endothelial dysfunction is a feature of the diabetic state itself. In Type II diabetes, endothelial function is impaired from the onset of the disease and is strongly related to adverse outcomes. It is not clear whether impaired endothelial function is caused by hyperglycaemia or by other factors. Impaired endothelial function is closely associated with and may contribute to insulin resistance regardless of the presence of diabetes. Endothelial dysfunction in diabetes originates from three main sources. Hyperglycaemia and its immediate biochemical sequelae directly alter endothelial function or influence endothelial cell functioning indirectly by the synthesis of growth factors, cytokines and vasoactive agents in other cells. Finally, the components of the metabolic syndrome can impair endothelial function.

Nitric oxide-dependent synthesis of vascular endothelial growth factor is impaired by high glucose

Synthesis of vascular endothelial growth factor (VEGF), the major angiogenic molecule, is induced by nitric oxide (NO) in various cell types, including vascular smooth muscle cells (VSMC). Therefore, compounds which inhibit NO generation can also influence VEGF synthesis. Here we investigated the effect of increased glucose concentration (25 mM vs. 5.5 mM) on cytokine-induced VEGF synthesis in rat VSMC. The cells growing in the medium containing 5.5 mM glucose and exposed to IL-1-beta, TNF-alpha and IFN-gamma induced expression of an inducible isoform of nitric oxide synthase (NOS II). This is followed by generation of NO and the concomitant expression of VEGF gene and release of VEGF protein. In contrast, 25 mM glucose impaired induction of NOS II expression and thus NO synthesis was lower than in 5.5 mM glucose. Consequently, the VEGF promoter activation was attenuated, resulting in decreased mRNA synthesis and lower production of VEGF protein. The results indicate that abnormally high concentrations of glucose can impair generation of NO and the NO-dependent VEGF synthesis. This may play a role in the development and progression of vascular dysfunctions in cardiovascular diseases.

Vascular endothelial growth factor - basic science and its clinical implications

Vascular endothelial growth factor (VEGF) is the most important signaling molecule involved in the regulation of the formation of new vessels. Results of recent studies have provided new insights into the molecular mechanisms of the VEGF signaling pathways. VEGF local or systemic application represents a new approach in the therapy of ischemic diseases, especially of the coronary artery disease. Inhibition of the VEGF action on various levels is, on the other hand, assumed to be a promising therapeutic concept against cancer. Moreover, VEGF has been recently shown to be associated with some other physiological and pathophysiological processes. In this article we summarize the latest results of VEGF related studies and present the concluding theoretical resource for further research on the role of VEGF in understanding of pathophysiology of diseases and in therapeutic interventions in clinical biomedicine.

Anemia and diabetes

World Health Organization statistics identify 150 million people with diabetes mellitus worldwide and suggest that this figure may double by 2025. In countries with a western lifestyle, the number of patients admitted for renal replacement therapy with diabetes as a co-morbid condition has increased significantly up to three to four times in a period of 10 years. Diabetes and renal failure are thus tightly linked diseases, and so is anemia. However, whether anemia may be worsened and/or directly, at least in part, caused by diabetes is not clearly elucidated yet. In this article, we review the prevalence, pathophysiology and consequences of anemia in diabetic patients.

Vascular Endothelial Growth Factor in Gingival Tissues and Crevicular Fluids of Diabetic and Healthy Periodontal Patients

BACKGROUND

Periodontal disease is one of the major oral problems encountered in patients with diabetes mellitus (DM). Vascular changes, neutrophil dysfunction, altered collagen synthesis, and genetic predisposition observed in DM may contribute to periodontitis; and the vascular alterations observed in such patients may depend on vascular endothelial growth factor (VEGF) actions. Few reports are available about the mechanism of neovascularization and the angiogenic factors that contribute to the periodontal pathology and the role of VEGF in periodontal diseases. The aim of this study is to compare VEGF expression in healthy and periodontally diseased tissues with gingival crevice fluid (GCF) of healthy persons and diabetic patients.

METHODS

Gingival tissue and GCF samples were collected from sites of periodontitis in 10 healthy subjects and in 10 type 2 diabetic patients, and from the sites of healthy gingiva within the same groups. Therefore, each patient became his/her own control. Additionally, 10 people without any systemic or periodontal diseases were enrolled, forming a negative control group. Thus, a total of 50 tissue and 50 GCF samples were provided.

RESULTS

No VEGF staining was observed in the negative control group or in the systemically healthy people's healthy tissue samples, whereas four samples of diabetic patients showed positive staining (P < 0.05). However, VEGF was revealed in two tissue samples of periodontal sites of systemically healthy people and in six samples of the diabetic patients (P > 0.05). In all test groups, GCF VEGF levels were higher in periodontal sites (P < 0.05) than in healthy sites.

CONCLUSION

The results of this study showed that VEGF is increased in all periodontal tissues of both groups and in the healthy sites of diabetic patients. Additionally, GCF VEGF values increased in periodontal sites of all test groups.

High glucose enhances interleukin-6-induced vascular endothelial growth factor 165 expression via activation of gp130-mediated p44/42 MAPK-CCAAT/enhancer binding protein signaling in gingival fibroblasts

Diabetic patients are susceptible to severe inflammatory periodontitis manifesting as swollen gingiva with bleeding, but the underlying mechanism is not well understood. Our purpose was to determine the effect of a high glucose (HG) condition on the interleukin-6/soluble interleukin-6 receptor (IL-6/sIL-6R)-induced activation of signaling and vascular endothelial growth factor (VEGF) expression in human gingival fibroblasts (HGFs). In this study, HGFs were cultured for at least two passages under a normal glucose (NG; 5.5 mM) condition or high glucose (25 mM) condition. Importantly, the HG condition significantly induced expression of gp130 mRNA in HGFs compared with levels in control cells. Consistent with the expression of its mRNA, the HG condition also increased the expression of gp130 protein, and phosphorylation of the tyrosine residue by gp130 was enhanced significantly by IL-6/sIL-6R stimulation. Furthermore, the HG condition enhanced the IL-6/sIL-6R-induced phosphorylation of p44/42 MAPK and led to subsequent activation of CCAAT/enhancer binding protein in nuclei. In contrast, there was no significant difference in phosphorylation of JNK between the HG and NG condition. Interestingly, HGFs increased IL-6/sIL-6R-induced VEGF165 mRNA expression and VEGF165 secretion under the HG condition compared with levels under the NG condition. In contrast, the induction of VEGF165 secretion was partially inhibited by PD98059 (selective p44/42 MAPK inhibitor) under the HG condition. In addition, the VEGF165 secretion was completely inhibited by the combination of PD98059 and SP600125 (JNK inhibitor). Our findings suggest that the HG condition indirectly increases VEGF expression via activation of gp130-mediated p44/42 MAPK-CCAAT/enhancer binding protein signaling in HGFs. Thus, elevated VEGF secretion in HGFs under the HG condition may play a role in the development of the severe periodontitis observed in diabetic patients.

The role of advanced glycation in the pathogenesis of diabetic retinopathy

Retinopathy is one of the commonest microvascular complications of diabetes and is still the prevailing cause of registerable blindness in the working population of developed countries. The clinicopathology of microvascular lesions and the dysregulation of an array of biochemical pathways in the diabetic retina have been extensively studied, although the relative contribution of various biochemical sequelae of hyperglycaemia remains ill- defined. There is little doubt that the pathogenesis of this diabetic complication is highly complex and there is a pressing need to establish new therapeutic regimens that can effectively prevent or retard the initiation and progression of retinal microvascular cell dysfunction and death which is characteristic of the vasodegenerative stages of diabetic retinopathy. Among the several pathogenic mechanisms that may contribute to diabetic retinopathy are the formation and accumulation of advanced glycation endproducts (AGEs). AGEs can form on the amino groups of proteins, lipids, and DNA through a number of complex pathways, including nonenzymatic glycation by glucose and reaction with metabolic intermediates and reactive dicarbonyl intermediates. These reactions not only modify the structure and function of proteins, but also cause intramolecular and intermolecular cross-link formation. AGEs are known to accumulate in the diabetic retina where they may have important effects on retinal vascular cell function in vitro and in vivo. Evidence now points toward a pathogenic role for advanced glycation in the initiation and progression of diabetic retinopathy. This review will examine the basis of AGE-related pathology in the diabetic retina at cellular and molecular levels. It will also outline how recent strategies to inhibit AGE formation or limit their pathogenic influence during chronic diabetes may have an important role to play in the treatment of retinopathy.

Autologous bone marrow cell implantation as therapeutic angiogenesis for ischemic hindlimb in diabetic rat model

The angiogenic effect induced by autologous bone marrow cell implantation (BMCI) was examined in the ischemic hindlimbs of diabetic and nondiabetic rats. Diabetes mellitus was induced by the systemic administration of streptozotocin. We investigated the production of angiogenic factors and endothelial differentiation from bone marrow cells and the native recovery of blood flow in the ischemic hindlimbs. To observe the angiogenic effect induced by BMCI treatment, 6 x 10(7) bone marrow cells were injected intramuscularly at six points into the ischemic limbs, and regional perfusion recovery was evaluated with colored microspheres 2 wk later. No difference was found between diabetic and nondiabetic rats in the release of angiogenic factors or endothelial differentiation from bone marrow cells in vitro. The levels of nitric oxide in plasma were significantly lower, and native perfusion recovery in the ischemic hindlimbs was significantly slower in the diabetic rats than in the nondiabetic rats. However, although perfusion recovery was achieved in the ischemic hindlimbs, there was no significant increase in systemic VEGF after BMCI treatment in either the diabetic or nondiabetic rats. Therefore, therapeutic angiogenesis induced by BMCI could be a safe and effective treatment for ischemic limb disease in diabetic patients.