Vascular endothelial growth factor-A-induced chemotaxis of monocytes is attenuated in patients with diabetes mellitus: A potential predictor for the individual capacity to develop collaterals

Study on mitogenic activity of serum from patients with total coronary occlusions: relation to duration of occlusion

In contrast to the extensive evidence from animal studies, only few human data are available on the relation of vascular growth factors and collateral function as well as on the conditions which may modify their release or function. In 31 patients with total coronary occlusion (TCOs) blood was collected from distal to the occlusion site (collateral circulation) and from the aortic root (systemic circulation). Serum was used to assess its mitogenic potential in [3H]-thymidine incorporation assay on human umbilical vein endothelial cells. Serum from patients with the duration of occlusion between 1 and 3 months was significantly more mitogenic as compared to either shorter or longer duration of occlusion. None of the demographic or clinical factors correlated with the mitogenic activity of serum. Serum from patients with TCOs shows a particular time-dependent mitogenic profile with a maximal activity between 1 and 3 months following the occlusion. This profile corresponds to the experimentally described time-line of strongest collateral development and indicates the time-window for possible modification.

A subpopulation of tissue remodeling monocytes stimulates revascularization of the ischemic limb

Despite decades of effort aimed at developing clinically effective cell therapies, including mixed population mononuclear cells, to revascularize the ischemic limb, there remains a paucity of patient-based studies that inform the function and fate of candidate cell types. In this study, we showed that circulating proangiogenic/arteriogenic monocytes (PAMs) expressing the FcγIIIA receptor CD16 were elevated in patients with chronic limb-threatening ischemia (CLTI), and these amounts decreased after revascularization. Unlike CD16-negative monocytes, PAMs showed large vessel remodeling properties in vitro when cultured with endothelial cells and smooth muscle cells and promoted salvage of the ischemic limb in vivo in a mouse model of hindlimb ischemia. PAMs showed a propensity to migrate toward and bind to ischemic muscle and to secrete angiogenic/arteriogenic factors, vascular endothelial growth factor A (VEGF-A) and heparin-binding epidermal growth factor. We instigated a first-in-human single-arm cohort study in which autologous PAMs were injected into the ischemic limbs of five patients with CLTI. Greater than 25% of injected cells were retained in the leg for at least 72 hours, of which greater than 80% were viable, with evidence of enhanced large vessel remodeling in the injected muscle area. In summary, we identified up-regulation of a circulatory PAM subpopulation as an endogenous response to limb ischemia in CLTI and tested a potentially clinically relevant therapeutic strategy.

Cutaneous changes in diabetic patients: Primed for aberrant healing?

Cutaneous manifestations affect most patients with diabetes mellitus, clinically presenting with numerous dermatologic diseases from xerosis to diabetic foot ulcers (DFUs). Skin conditions not only impose a significantly impaired quality of life on individuals with diabetes but also predispose patients to further complications. Knowledge of cutaneous biology and the wound healing process under diabetic conditions is largely limited to animal models, and studies focusing on biology of the human condition of DFUs remain limited. In this review, we discuss the critical molecular, cellular, and structural changes to the skin in the hyperglycaemic and insulin-resistant environment of diabetes with a focus specifically on human-derived data. Elucidating the breadth of the cutaneous manifestations coupled with effective diabetes management is important for improving patient quality of life and averting future complications including wound healing disorders.

A role for macrophages under cytokine control in mediating resistance to ADI-PEG20 (pegargiminase) in ASS1-deficient mesothelioma

BACKGROUND

Pegylated arginine deiminase (ADI-PEG20; pegargiminase) depletes arginine and improves survival outcomes for patients with argininosuccinate synthetase 1 (ASS1)-deficient malignant pleural mesothelioma (MPM). Optimisation of ADI-PEG20-based therapy will require a deeper understanding of resistance mechanisms, including those mediated by the tumor microenvironment. Here, we sought to reverse translate increased tumoral macrophage infiltration in patients with ASS1-deficient MPM relapsing on pegargiminase therapy.

METHODS

Macrophage-MPM tumor cell line (2591, MSTO, JU77) co-cultures treated with ADI-PEG20 were analyzed by flow cytometry. Microarray experiments of gene expression profiling were performed in ADI-PEG20-treated MPM tumor cells, and macrophage-relevant genetic "hits" were validated by qPCR, ELISA, and LC/MS. Cytokine and argininosuccinate analyses were performed using plasma from pegargiminase-treated patients with MPM.

RESULTS

We identified that ASS1-expressing macrophages promoted viability of ADI-PEG20-treated ASS1-negative MPM cell lines. Microarray gene expression data revealed a dominant CXCR2-dependent chemotactic signature and co-expression of VEGF-A and IL-1α in ADI-PEG20-treated MPM cell lines. We confirmed that ASS1 in macrophages was IL-1α-inducible and that the argininosuccinate concentration doubled in the cell supernatant sufficient to restore MPM cell viability under co-culture conditions with ADI-PEG20. For further validation, we detected elevated plasma VEGF-A and CXCR2-dependent cytokines, and increased argininosuccinate in patients with MPM progressing on ADI-PEG20. Finally, liposomal clodronate depleted ADI-PEG20-driven macrophage infiltration and suppressed growth significantly in the MSTO xenograft murine model.

CONCLUSIONS

Collectively, our data indicate that ADI-PEG20-inducible cytokines orchestrate argininosuccinate fuelling of ASS1-deficient mesothelioma by macrophages. This novel stromal-mediated resistance pathway may be leveraged to optimize arginine deprivation therapy for mesothelioma and related arginine-dependent cancers.

The Sodium-Glucose Co-Transporter 2 (SGLT2) Inhibitor Empagliflozin Reverses Hyperglycemia-Induced Monocyte and Endothelial Dysfunction Primarily through Glucose Transport-Independent but Redox-Dependent Mechanisms

PURPOSE

Hyperglycaemia-induced oxidative stress and inflammation contribute to vascular cell dysfunction and subsequent cardiovascular events in T2DM. Selective sodium-glucose co-transporter-2 (SGLT-2) inhibitor empagliflozin significantly improves cardiovascular mortality in T2DM patients (EMPA-REG trial). Since SGLT-2 is known to be expressed on cells other than the kidney cells, we investigated the potential ability of empagliflozin to regulate glucose transport and alleviate hyperglycaemia-induced dysfunction of these cells.

METHODS

Primary human monocytes were isolated from the peripheral blood of T2DM patients and healthy individuals. Primary human umbilical vein endothelial cells (HUVECs) and primary human coronary artery endothelial cells (HCAECs), and fetoplacental endothelial cells (HPECs) were used as the EC model cells. Cells were exposed to hyperglycaemic conditions in vitro in 40 ng/mL or 100 ng/mL empagliflozin. The expression levels of the relevant molecules were analysed by RT-qPCR and confirmed by FACS. Glucose uptake assays were carried out with a fluorescent derivative of glucose, 2-NBDG. Reactive oxygen species (ROS) accumulation was measured using the H₂DFFDA method. Monocyte and endothelial cell chemotaxis were measured using modified Boyden chamber assays.

RESULTS

Both primary human monocytes and endothelial cells express SGLT-2. Hyperglycaemic conditions did not significantly alter the SGLT-2 levels in monocytes and ECs in vitro or in T2DM conditions. Glucose uptake assays carried out in the presence of GLUT inhibitors revealed that SGLT-2 inhibition very mildly, but not significantly, suppressed glucose uptake by monocytes and endothelial cells. However, we detected the significant suppression of hyperglycaemia-induced ROS accumulation in monocytes and ECs when empagliflozin was used to inhibit SGLT-2 function. Hyperglycaemic monocytes and endothelial cells readily exhibited impaired chemotaxis behaviour. The co-treatment with empagliflozin reversed the PlGF-1 resistance phenotype of hyperglycaemic monocytes. Similarly, the blunted VEGF-A responses of hyperglycaemic ECs were also restored by empagliflozin, which could be attributed to the restoration of the VEGFR-2 receptor levels on the EC surface. The induction of oxidative stress completely recapitulated most of the aberrant phenotypes exhibited by hyperglycaemic monocytes and endothelial cells, and a general antioxidant N-acetyl-L-cysteine (NAC) was able to mimic the effects of empagliflozin.

CONCLUSIONS

This study provides data indicating the beneficial role of empagliflozin in reversing hyperglycaemia-induced vascular cell dysfunction. Even though both monocytes and endothelial cells express functional SGLT-2, SGLT-2 is not the primary glucose transporter in these cells. Therefore, it seems likely that empagliflozin does not directly prevent hyperglycaemia-mediated enhanced glucotoxicity in these cells by inhibiting glucose uptake. We identified the reduction of oxidative stress by empagliflozin as a primary reason for the improved function of monocytes and endothelial cells in hyperglycaemic conditions. In conclusion, empagliflozin reverses vascular cell dysfunction independent of glucose transport but could partially contribute to its beneficial cardiovascular effects.

Upregulated miR-18a-5p in Colony Forming Unit-Hill’s in Subclinical Cardiovascular Disease and Metformin Therapy; MERIT Study

Colony forming unit-Hill’s (CFU-Hill’s) colonies are hematopoietic-derived cells that participate in neovasculogenesis and serve as a biomarker for vascular health. In animals, overexpression of miR-18a-5p was shown to be pro-atherogenic. We had shown that well-controlled type 1 diabetes mellitus (T1DM) is characterized by an inflammatory state, endothelial dysfunction, and reduced number of CFU-Hill’s, a model of subclinical cardiovascular disease (CVD). MERIT study explored the role of miR-18a-5p expression in CFU-Hill’s colonies in T1DM, and the cardioprotective effect of metformin in subclinical CVD. In T1DM, miR-18a-5p was significantly upregulated whereas metformin reduced it to HC levels. MiR-18a-5p was inversely correlated with CFU-Hill’s colonies, CD34+, CD34+CD133+ cells, and positively with IL-10, C-reactive protein, vascular endothelial growth factor-D (VEGF-D), and thrombomodulin. The receiver operating characteristic curve demonstrated, miR-18a-5p as a biomarker of T1DM, and upregulated miR-18a-5p defining subclinical CVD at HbA1c of 44.5 mmol/mol (pre-diabetes). Ingenuity pathway analysis documented miR-18a-5p inhibiting mRNA expression of insulin-like growth factor-1, estrogen receptor-1, hypoxia-inducible factor-1α cellular communication network factor-2, and protein inhibitor of activated STAT 3, whilst metformin upregulated these mRNAs via transforming growth factor beta-1 and VEGF. We confirmed the pro-atherogenic effect of miR-18a-5p in subclinical CVD and identified several target genes for future CVD therapies.

Effect of the Human Amniotic Membrane on the Umbilical Vein Endothelial Cells of Gestational Diabetic Mothers: New Insight on Inflammation and Angiogenesis

One of the most relevant diabetes complications is impaired wound healing, mainly characterized by reduced peripheral blood flow and diminished neovascularization together with increased inflammation and oxidative stress. Unfortunately, effective therapies are currently lacking. Recently, the amniotic membrane (AM) has shown promising results in wound management. Here, the potential role of AM on endothelial cells isolated from the umbilical cord vein of gestational diabetes-affected women (GD-HUVECs), has been investigated. Indeed, GD-HUVECs in vivo exposed to chronic hyperglycemia during pregnancy compared to control cells (C-HUVECs) have shown molecular modifications of cellular homeostasis ultimately impacting oxidative and nitro-oxidative stress, inflammatory phenotype, nitric oxide (NO) synthesis, and bioavailability, thus representing a useful model for studying the mechanisms potentially supporting the role of AM in chronic non-healing wounds. In this study, the anti-inflammatory properties of AM have been assessed using a monocyte–endothelium interaction assay in cells pre-stimulated with tumor necrosis factor-α (TNF-α) and through vascular adhesion molecule expression and membrane exposure, together with the AM impact on the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kB) pathway and NO bioavailability. Moreover, GD-HUVEC migration and tube formation ability were evaluated in the presence of AM. The results showed that AM significantly reduced TNF-α-stimulated monocyte–endothelium interaction and the membrane exposure of the endothelial vascular and intracellular adhesion molecules (VCAM-1 and ICAM-1, respectively) in both C- and GD-HUVECs. Strikingly, AM treatment significantly improved vessel formation in GD-HUVECs and cell migration in both C- and GD-HUVECs. These collective results suggest that AM positively affects various critical pathways in inflammation and angiogenesis, thus providing further validation for ongoing clinical trials in diabetic foot ulcers.

Hypoxia-inducible factors: roles in cardiovascular disease progression, prevention, and treatment

Hypoxia-inducible factors (HIF)-1 and HIF-2 are master regulators of oxygen homeostasis that regulate the expression of thousands of genes in order to match O2 supply and demand. A large body of experimental data links HIF activity to protection against multiple disorders affecting the cardiovascular system: ischemic cardiovascular disease (including coronary artery disease and peripheral artery disease), through collateral blood vessel formation and preconditioning phenomena; emphysema; lymphedema; and lung transplant rejection. In these disorders, strategies to increase the expression of one or both HIFs may be of therapeutic utility. Conversely, extensive data link HIFs to the pathogenesis of pulmonary arterial hypertension and drugs that inhibit one or both HIFs may be useful in treating this disease.

Measurement of Revascularization in the Hind Limb After Experimental Ischemia in Mice

Peripheral vascular disease is a major cause of morbidity and mortality, and is a consequence of impaired blood flow to the limbs. This arises due to the inability of the tissue to develop sufficiently functional collateral vessel circulation to overcome occluded arteries, or microvascular impairment. The mouse hind limb model of hind limb ischemia can be used to investigate the impact of different treatment modalities, behavioral changes, or genetic knockout. Here we described the model in detail, providing examples of adverse events, and details of ex vivo analysis of blood vessel density.

RUNX1 and CCL3 in Diabetes Mellitus-Related Coronary Artery Disease: A Bioinformatics Analysis

BACKGROUND

Cardiovascular complications are a major cause of death and disability in patients with diabetes mellitus, but how such complications arise is unclear.

METHODS

Weighted gene correlation network analysis (WGCNA) was performed on gene expression profiles from healthy controls, individuals with diabetes mellitus, and individuals with diabetes mellitus-associated coronary artery disease (DMCAD). Phenotypically related module genes were analyzed for enrichment in Gene Ontology (GO) terms and Kyoto Gene and Genome Encyclopedia (KEGG) pathways. Predicted biological functions were validated using gene set enrichment analysis (GSEA) and ClueGo analysis. Based on the TRRUST v2 database and hypergeometric tests, a global network was built to identify transcription factors (TFs) and downstream target genes potentially involved in DMCAD.

RESULTS

WGCNA identified three modules associated with progression from diabetes mellitus to DMCAD. The module genes were significantly involved in biological processes related to interferon and viral infection, while GSEA of DMCAD samples suggested involvement in viral myocarditis, chemokine signaling and phagosomes. RUNX1 was identified as a potential TF regulating these module genes. Analysis of the global regulatory network of TFs and their targets suggested that CCL3 may be a key regulator in DMCAD.

CONCLUSION

We found bioinformatic evidence that CCL3 may be a key regulator and RUNX1 a key TF in DMCAD.

Indicators and predictors of in-hospital mortality and survival in patients with ventricular septal rupture

Background

Ventricular septal rupture (VSR), a mechanical complication of myocardial infarction (MI), usually presents with rapid clinical deterioration with acute heart failure or cardiogenic shock. VSR may occur within 24 h to several days after MI and can occur in both anterior and inferior wall MI. Although guidelines recommend emergent surgery, this is associated with a high mortality rate of up to 40%. Intra-aortic balloon pump (IABP) and extracorporeal membrane oxygenation (ECMO) stabilize patients in preparation for angiography and surgery. Delayed surgery allows better septal repair in scarring tissue but also carries the risk of rupture extension and death while waiting. Percutaneous closure of the defect with appropriately designed devices results in better survival in the subacute phase.

Aims

To study the indicators and predictors of VSR in the current era of primary percutaneous coronary interventions and mechanical circulatory support.

Methods

Of total of 34,681 patients presenting with MI, the incidence of VSR was 0.45%. We sought to evaluate the predictors of survival and death in VSR. Coronary angiography (CAG) was performed, hemodynamic support provided to unstable patients, and consenting patients were referred to definitive therapy, either surgery or percutaneous device closure. The previously postulated hypotheses of triple vessel disease (TVD), diabetes mellitus (DM), and concentric left ventricular hypertrophy (LVH) due to Hypertension (HTN) being protective against VSR were explored.

Results

Of the 169 patients with VSR, we found that the group that survived was mostly men and the mean age was 61.5 years; this was in contrast to the non-survivors, who were mainly women, and the mean age was 65.2 years (p = 0.025); higher Killip Class was 111-1V (p = 0.001), lower LVEF (p = 0.010), apical VSR and LV aneurysm (p = 0.015 and p = 0.002, respectively) were predictors of death. 48 patients underwent CAG, with single vessel disease (SVD) with lower-grade Rentrop collateral flow being most common in the death group. 25 patients were subjected to definitive therapy with surgical patch closure or percutaneous device closure. The patients who died were older by approximately 7 years. The risk factors for coronary artery disease, such as HTN, diabetes, and smoking, were not statistically different between the two groups.

Conclusion

Prevention of myocardial infarction is more important than managing a VSR, which carries a high mortality despite advanced mechanical support and definitive interventional therapy such as emergent surgery and percutaneous device closure.

Trimetazidine ameliorates hindlimb ischaemic damage in type 2 diabetic mice

BACKGROUND

Ischaemia caused by lower extremity artery stenosis is the main cause of peripheral artery disease (PAD) in patients with diabetes. Trimetazidine (TMZ) has traditionally been used as an anti-ischaemic drug for coronary artery disease. The effect of TMZ on PAD in a diabetic animal model and the underlying molecular mechanisms remain unclear.

METHODS

The db/db mice were challenged with femoral artery ligation (FAL), followed by TMZ treatment for 2 weeks. Scores on hindlimb ischaemia and function were evaluated. Histological and capillary density analyses of gastrocnemius were performed. The expression of vascular endothelial growth factor (VEGF) and myogenic regulators was also confirmed by Western blotting. We also detected serum intercellular adhesion molecule 1 (ICAM-1) level through ELISA.

RESULTS

Diabetic mice exhibited limb ulceration and motor dysfunction after FAL while TMZ-treated db/db mice exhibited milder ischaemic impairment. Furthermore, decreased capillary density in the gastrocnemius muscles of ischaemic hindlimb and reduced expressions of VEGF, myogenic markers, and serum ICAM-1 could be partially reversed by TMZ treatment.

CONCLUSION

TMZ may alleviate hindlimb ischaemic damage in db/db mice, at least partly, through enhancing angiogenesis and promoting myogenesis in ischaemia region.Key messagesTMZ intervention could alleviate hindlimb ischaemic damage in db/db mice.TMZ intervention could enhance angiogenesis and stimulate myogenesis in ischaemia region.

The Anti-inflammatory and Proangiogenic Properties of High-Density Lipoproteins: An Emerging Role in Diabetic Wound Healing

Significance: Prolonged inflammation and impaired angiogenesis are the two principal factors that prevent successful wound healing, which is exacerbated in people with diabetes. There is a significant need for new wound healing treatments that target both these factors simultaneously. This review discusses the emerging evidence that high-density lipoproteins (HDL) have pleiotropic wound healing benefits. Recent Advances: Numerous in vitro and in vivo studies have demonstrated the anti-inflammatory and proangiogenic effects of HDL. In endothelial cells, HDL mediate these effects through interaction with the scavenger receptor SR-BI, which activates the PI3K/Akt pathway, causing a decrease in inflammatory protein production and an increase in proangiogenic growth factors. In macrophages, HDL inhibit inflammation through suppression of the nuclear factor kappa B activation pathway. This review details the molecular disturbances that cause impaired wound healing in diabetes with a particular focus on inflammation and angiogenesis and the pathways in which HDL provide benefit. Critical Issues: Diabetic foot ulcers (DFUs) impose a major public health challenge worldwide. It is estimated that 20% patients with DFUs require amputation, which is accompanied by a significant social and economic burden. To date, there are no therapeutic agents with pleiotropic effects that actively improve wound healing, highlighting a therapeutic void for this complex disease.

Upregulated anti-angiogenic miR-424-5p in type 1 diabetes (model of subclinical cardiovascular disease) correlates with endothelial progenitor cells, CXCR1/2 and other parameters of vascular health

Background

In spite of clinical progress, cardiovascular disease (CVD) remains the predominant cause of mortality worldwide. Overexpression studies in animals have proven miR-424-5p to have anti-angiogenic properties. As type 1 diabetes mellitus (T1DM) without CVD displays endothelial dysfunction and reduced circulating endothelial progenitor cells (cEPCs), it offers a model of subclinical CVD. Therefore, we explored miR-424-5p, cytokines and vascular health in T1DM.

Methods

Twenty-nine well-controlled T1DM patients with no CVD and 20-matched controls were studied. Cytokines IL8, TNF-α, IL7, VEGF-C, cEPCs/CD45^dimCD34⁺CD133⁺ cells and ex-vivo proangiogenic cells (PACs)/fibronectin adhesion assay (FAA) were measured. MiR-424-5p in plasma and peripheral blood mononuclear cells (PBMC) along with mRNAs in PBMC was evaluated.

Results

We found an elevation of IL7 (p = 0.008), IL8 (p = 0.003), TNF-α (p = 0.041), VEGF-C (p = 0.013), upregulation of mRNA CXCR1 (p = 0.009), CXCR2 (p < 0.001) and reduction of cEPCs (p < 0.001), PACs (p < 0.001) and FAA (p = 0.017) in T1DM. MiR-424-5p was upregulated in T1DM in PBMC (p < 0.001). MiR-424-5p was negatively correlated with cEPCs (p = 0.006), PACs (p = 0.005) and FAA (p < 0.001) and positively with HbA_1c (p < 0.001), IL7 (p = 0.008), IL8 (p = 0.017), VEGF-C (p = 0.007), CXCR1 (p = 0.02) and CXCR2 (p = 0.001). ROC curve analyses showed (1) miR-424-5p to be a biomarker for T1DM (p < 0.001) and (2) significant upregulation of miR-424-5p, defining subclinical CVD, occurred at HbA_1c of 46.5 mmol/mol (p = 0.002).

Conclusion

We validated animal research on anti-angiogenic properties of miR-424-5p in T1DM. MiR-424-5p may be a biomarker for onset of subclinical CVD at HbA_1c of 46.5 mmol/mol (pre-diabetes). Thus, miR-424-5p has potential use for CVD monitoring whilst anti-miR-424-5p-based therapies may be used to reduce CVD morbidity/mortality in T1DM.

Transforming growth factor-β1 signalling triggers vascular endothelial growth factor resistance and monocyte dysfunction in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) leads to monocyte dysfunction associated with atherogenesis and defective arteriogenesis. Transforming growth factor (TGF)-β1, placenta growth factor (PlGF)-1 and vascular endothelial growth factor (VEGF)A play important roles in atherogenesis and arteriogenesis. VEGF-receptor (VEGFR)-mediated monocyte migration is inhibited in T2DM (VEGFA resistance), while TGF-β1-induced monocyte migration is fully functional. Therefore, we hypothesize that TGF-β antagonises the VEGFA responses in human monocytes. We demonstrate that monocytes from T2DM patients have an increased migratory response towards low concentrations of TGF-β1, while PlGF-1/VEGFA responses are mitigated. Mechanistically, this is due to increased expression of type II TGF-β receptor in monocytes under high-glucose conditions and increased expression of soluble (s)VEGFR1, which is known to interfere with VEGFA signalling. VEGFA resistance in monocytes from T2DM patients can be rescued by either experimental down-regulation of TGF-β receptor expression in vitro or by functional blocking of TGF-β signalling using either a TGF-β receptor kinase inhibitor or a TGF-β neutralizing antibody. Our data demonstrate that both T2DM and high-glucose potentiate the TGF-β pathway. TGF-β signalling impairs VEGFR-mediated responses in T2DM monocytes and in this way contributes to mononuclear cell dysfunction, provide novel insights into T2DM vascular dysfunction.

An oral absorbent, AST-120, restores vascular growth and blood flow in ischemic muscles in diabetic mice via modulation of macrophage transition

Background Diabetes has a pronounced effect on the peripheral vasculature. The accumulation of advanced glycation end products (AGEs) is regarded as the crucial mechanism responsible for vascular damage in diabetes, but it is not easy to be avoided from food. In this study, we aimed to investigate the effects of an oral absorbent, AST-120, on the accumulation of AGEs and changes in blood flow recovery in diabetic mice. Methods The mice were divided into four groups, wild-type (WT) mice without treatment, WT mice treated with 5% AST-120 mixed into pulverized chow, streptozotocin-induced diabetes mellitus (DM) mice, and DM mice treated with 5% AST-120. Six weeks after hind-limb ischemia surgery, blood flow reperfusion, histology, plasma AGE, and cytokine were examined. Bone marrow cells were cultured and derived into macrophages to evaluate the effects of AGEs on macrophage polarization. Results Plasma AGEs were significantly increased in diabetic mice. AST-120 could bind to AGEs and reduced their plasma concentrations. Histological analysis revealed fewer collateral vessels with corresponding impairment of blood flow recovery in diabetic mice. In these mice, AGE-positive and AGE receptor-positive macrophages were numerous in ischemic limbs compared with non- diabetic mice. In diabetic mice, macrophages in ischemic tissues demonstrated greater M1 polarization than M2 polarization; this pattern was reversed in the AST-120 treatment group. The change in macrophage polarization was associated with the corresponding expression of pro-inflammatory cytokines in the ischemic tissues. In cell cultures, AGEs triggered the transformation of bone marrow-derived macrophages into the M1 phenotype. The alterations in the polarization of macrophages were reversed after treatment with AST-120. Conclusions Oral administration of AST-120 decreased the serum levels of AGEs in diabetic mice and improved neovascularization of ischemic limbs. This benefit may be due to, at least partially, the alterations in macrophage polarization and the associated changes in inflammatory cytokines.

Growth Factor Deregulation and Emerging Role of Phosphatases in Diabetic Peripheral Artery Disease

Peripheral artery disease is caused by atherosclerosis of lower extremity arteries leading to the loss of blood perfusion and subsequent critical ischemia. The presence of diabetes mellitus is an important risk factor that greatly increases the incidence, the progression and the severity of the disease. In addition to accelerated disease progression, diabetic patients are also more susceptible to develop serious impairment of their walking abilities through an increased risk of lower limb amputation. Hyperglycemia is known to alter the physiological development of collateral arteries in response to ischemia. Deregulation in the production of several critical pro-angiogenic factors has been reported in diabetes along with vascular cell unresponsiveness in initiating angiogenic processes. Among the multiple molecular mechanisms involved in the angiogenic response, protein tyrosine phosphatases are potent regulators by dephosphorylating pro-angiogenic tyrosine kinase receptors. However, evidence has indicated that diabetes-induced deregulation of phosphatases contributes to the progression of several micro and macrovascular complications. This review provides an overview of growth factor alterations in the context of diabetes and peripheral artery disease, as well as a description of the role of phosphatases in the regulation of angiogenic pathways followed by an analysis of the effects of hyperglycemia on the modulation of protein tyrosine phosphatase expression and activity. Knowledge of the role of phosphatases in diabetic peripheral artery disease will help the development of future therapeutics to locally regulate phosphatases and improve angiogenesis.

Skin well-being in diabetes: Role of macrophages

Macrophages are key players in wound healing- along with mediating the acute inflammatory response, macrophages activate cutaneous epithelial cells and promote tissue repair. Diabetes complications, including diabetic chronic wounds, are accompanied by persistent inflammation and macrophage malfunction. Several studies indicate that hyperglycemia induces various alterations that affect macrophage function in wound healing including epigenetic changes, imbalance between pro- and anti-inflammatory modulators, and insensitivity to proliferative stimuli. In this review, we briefly summarize recent studies regarding those alterations and their implications on skin well-being in diabetes.

Models for Monocytic Cells in the Tumor Microenvironment

Monocytes (Mos) are immune cells that critically regulate cancer, enabling tumor growth and modulating metastasis. Mos can give rise to tumor-associated macrophages (TAMs) and Mo-derived dendritic cells (moDCs), all of which shape the tumor microenvironment (TME). Thus, understanding their roles in the TME is key for improved immunotherapy. Concurrently, various biological and mechanical factors including changes in local cytokines, extracellular matrix production, and metabolic changes in the TME affect the roles of monocytic cells. As such, relevant TME models are critical to achieve meaningful insight on the precise functions, mechanisms, and effects of monocytic cells. Notably, murine models have yielded significant insight into human Mo biology. However, many of these results have yet to be confirmed in humans, reinforcing the need for improved in vitro human TME models for the development of cancer interventions. Thus, this chapter (1) summarizes current insight on the tumor biology of Mos, TAMs, and moDCs, (2) highlights key therapeutic applications relevant to these cells, and (3) discusses various TME models to study their TME-related activity. We conclude with a perspective on the future research trajectory of this topic.

High glucose environment induces M1 macrophage polarization that impairs keratinocyte migration via TNF-α: An important mechanism to delay the diabetic wound healing

BACKGROUND

Macrophages play important roles during wound healing, and delayed healing in diabetics is associated with sustained inflammation. M1 type macrophage is recognized to secrete excessive amount of tumor necrosis factor-alpha (TNF-α) as compared to its M2 counterpart.

OBJECTIVES

We hypothesized that macrophage polarization is different between diabetic and normal rats during skin wounding and has direct impact on keratinocyte function in the context of re-epithelialization.

METHODS

Skin wounds were created in diabetic and control rats. The phenotypes of infiltrating macrophages, the levels of TNF-α, and the rate of wound closure were determined. Using cell model, the effects of M1 type macrophage on keratinocyte migration were evaluated, and the potential regulatory pathways were determined.

RESULTS

The percentage of M1 macrophages and the levels of TNF-α expression were significantly higher in the perilesional area of diabetic rats as compared to control. The condition media (CM) from M1 type macrophage upregulated tissue inhibitor metalloproteinases (TIMP)-1 expression in keratinocytes and significantly reduced keratinocyte migratory capacity. Addition of neutralizing TNF-α antibody to the CM or gene-silencing of TIMP1 in keratinocytes restored the keratinocyte migratory capacity. Treating wounds of diabetic rats with TNF-α antagonist improved the wound healing process.

CONCLUSIONS

In summary, high glucose wound environment harbored more M1 macrophages infiltration, an event that created excess TNF-α micro-environment. TNF-α upregulated TIMP1 expression in keratinocytes and resulted in impaired keratinocyte migration. Taken together, these events contributed to impaired wound healing during diabetic condition, and targeting TNF-α is a potential therapeutic option to improve diabetic wound healing.

Angiogenic Abnormalities in Diabetes Mellitus: Mechanistic and Clinical Aspects

CONTEXT

Diabetes causes severe pathological changes to the microvasculature in many organs and tissues and is at the same time associated with an increased risk of coronary and peripheral macrovascular events. We herein review alterations in angiogenesis observed in human and experimental diabetes and how they contribute to diabetes onset and development of vascular complications.

EVIDENCE ACQUISITION

The English language medical literature was searched for articles reporting on angiogenesis/vasculogenesis abnormalities in diabetes and their clinical manifestations, mechanistic aspects, and possible therapeutic implications.

EVIDENCE SYNTHESIS

Angiogenesis is a complex process, driven by a multiplicity of molecular mechanisms and involved in several physiological and pathological conditions. Incompetent angiogenesis is pervasive in diabetic vascular complications, with both excessive and defective angiogenesis observed in various tissues. A striking different angiogenic response typically occurs in the retina vs the myocardium and peripheral circulation, but some commonalities in abnormal angiogenesis can explain the well-known association between microangiopathy and macroangiopathy. Impaired angiogenesis can also affect endocrine islet and adipose tissue function, providing a link to diabetes onset. Exposure to high glucose itself directly affects angiogenic/vasculogenic processes, and the mechanisms include defective responses to hypoxia and proangiogenic factors, impaired nitric oxide bioavailability, shortage of proangiogenic cells, and loss of pericytes.

CONCLUSIONS

Dissecting the molecular drivers of tissue-specific alterations of angiogenesis/vasculogenesis is an important challenge to devise new therapeutic approaches. Angiogenesis-modulating therapies should be carefully evaluated in view of their potential off-target effects. At present, glycemic control remains the most reasonable therapeutic strategy to normalize angiogenesis in diabetes.

Association between Biomarkers of Low-grade Inflammation and Sex Hormones in Women with Polycystic Ovary Syndrome

Objective Women with polycystic ovary syndrome (PCOS) have higher circulating levels of C-reactive protein, but the relationship between inflammation and endocrine function in PCOS remains poorly understood. Thus, this study aimed to investigate the association between low-grade inflammation and sex hormones in women with PCOS.

Design and Patients A comprehensive panel of biomarkers of inflammation was measured in serum of 63 women with PCOS using proximity extension assay technology. Associations of 65 biomarkers with sex hormones were assessed without and with adjustment for age and body mass index (BMI).

Results In the unadjusted analysis, 20 biomarkers were positively correlated with 17-OH-progesterone (17-OH-P), 14 with prolactin and 6 with free testosterone, whereas inverse associations were found for 16 biomarkers with sex hormone-binding globulin (SHBG), 6 with luteinizing hormone (LH) and 6 with estrogen (all p<0.05). Among the positive associations, correlations were mainly found for five chemokines (CXCL11, CCL4, MCP-4/CCL13, CXCL5, CXCL6) and for VEGF-A, LAP-TGFβ1, TNFSF14 and MMP-1. Inverse associations with sex hormones were mainly present for two chemokines (CXCL1, MCP-2/CCL8), CDCP1, CST5 and CSF-1. Adjustment for age and BMI reduced the number of biomarker associations for SHBG and estrogen, but had hardly any impact on associations with 17-OH-P, prolactin, free testosterone and LH.

Conclusion Women with PCOS feature BMI-independent associations between biomarkers of inflammation and certain sex steroid and hypophyseal hormones. Most of these inflammation-related biomarkers were chemokines, which may be relevant as potential mediators of the increased cardiometabolic risk of women with PCOS.

Hyperglycemia-Induced Aberrant Cell Proliferation; A Metabolic Challenge Mediated by Protein O-GlcNAc Modification

Chronic hyperglycemia has been associated with an increased prevalence of pathological conditions including cardiovascular disease, cancer, or various disorders of the immune system. In some cases, these associations may be traced back to a common underlying cause, but more often, hyperglycemia and the disturbance in metabolic balance directly facilitate pathological changes in the regular cellular functions. One such cellular function crucial for every living organism is cell cycle regulation/mitotic activity. Although metabolic challenges have long been recognized to influence cell proliferation, the direct impact of diabetes on cell cycle regulatory elements is a relatively uncharted territory. Among other "nutrient sensing" mechanisms, protein O-linked β-N-acetylglucosamine (O-GlcNAc) modification emerged in recent years as a major contributor to the deleterious effects of hyperglycemia. An increasing amount of evidence suggest that O-GlcNAc may significantly influence the cell cycle and cellular proliferation. In our present review, we summarize the current data available on the direct impact of metabolic changes caused by hyperglycemia in pathological conditions associated with cell cycle disorders. We also review published experimental evidence supporting the hypothesis that O-GlcNAc modification may be one of the missing links between metabolic regulation and cellular proliferation.

Phenolic and anthocyanin fractions from wild blueberries (V. angustifolium) differentially modulate endothelial cell migration partially through RHOA and RAC1

The present study investigates the effect of anthocyanin (ACN), phenolic acid (PA) fractions, and their combination (ACNs:PAs) from wild blueberry powder (Vaccinum angustifolium) on the speed of endothelial cell migration, gene expression, and protein levels of RAC1 and RHOA associated with acute exposure to different concentrations of ACNs and PAs. Time-lapse videos were analyzed and endothelial cell speed was calculated. Treatment with ACNs at 60 μg/mL inhibited endothelial cell migration rate ( P ≤ 0.05) while treatment with PAs at 0.002 μg/mL ( P ≤ 0.0001), 60 μg/mL ( P ≤ 0.0001), and 120 μg/mL ( P ≤ 0.01) significantly increased endothelial cell migration rate compared with control. Moreover, exposure of HUVECs to ACNs:PAs at 8:8 μg/mL ( P ≤ 0.05) and 60:60 μg/mL increased ( P ≤ 0.001) endothelial cell migration. Gene expression of RAC1 and RHOA significantly increased 2 hours after exposure with all treatments. No effect of the above fractions was observed on the protein levels of RAC1 and RHOA. Findings suggest that endothelial cell migration is differentially modulated based on the type of blueberry extract (ACN or PA fraction) and is concentration-dependent. Future studies should determine the mechanism of the differential action of the above fractions on endothelial cell migration.

Fenofibrate Rescues Diabetes-Related Impairment of Ischemia-Mediated Angiogenesis by PPARα-Independent Modulation of Thioredoxin-Interacting Protein

Fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, reduces lower limb amputations in patients with type 2 diabetes. The mechanism is, however, unknown. In this study, we demonstrate that fenofibrate markedly attenuates diabetes-related impairment of ischemia-mediated angiogenesis. In a murine model of hindlimb ischemia, daily oral fenofibrate treatment restored diabetes-impaired blood flow recovery, foot movement, hindlimb capillary density, vessel diameter, and vascular endothelial growth factor signaling to nondiabetic levels in both wild-type and PPARα-knockout mice, indicating that these fenofibrate effects are largely PPARα independent. In vitro, fenofibric acid (FFA) rescued high glucose-induced (25 mmol/L) impairment of endothelial cell migration, tubulogenesis, and survival in a PPARα-independent manner. Interestingly, fenofibrate in vivo and FFA in vitro reversed high glucose-induced expression of thioredoxin-interacting protein (TXNIP), an exquisitely glucose-inducible gene previously identified as a critical mediator of diabetes-related impairment in neovascularization. Conversely, adenoviral overexpression of TXNIP abrogated the restorative effects of FFA on high glucose-impaired endothelial cell function in vitro, indicating that the effects of FFA are mediated by TXNIP. We conclude that fenofibrate rescues diabetic impairment in ischemia-mediated angiogenesis, in large part, by PPARα-independent regulation of TXNIP. These findings may therefore explain the reduction in amputations seen in patients with diabetes treated with fenofibrate.

Hyperglycaemia-induced methylglyoxal accumulation potentiates VEGF resistance of diabetic monocytes through the aberrant activation of tyrosine phosphatase SHP-2/SRC kinase signalling axis

Diabetes mellitus (DM) is a major cardiovascular risk factor contributing to cardiovascular complications by inducing vascular cell dysfunction. Monocyte dysfunction could contribute to impaired arteriogenesis response in DM patients. DM monocytes show blunted chemotactic responses to arteriogenic stimuli, a condition termed as vascular endothelial growth factor (VEGF) resistance. We hypothesize that methylglyoxal (MG), a glucose metabolite, induces monocyte dysfunction and aimed to elucidate the underlying molecular mechanisms. Human monocytes exposed to MG or monocytes from DM patients or mice (db/db) showed VEGF-resistance secondary to a pro-migratory phenotype. Mechanistically, DM conditions or MG exposure resulted in the upregulation of the expression of SHP-2 phosphatase. This led to the enhanced activity of SHP-2 and aided an interaction with SRC kinase. SHP-2 dephosphorylated the inhibitory phosphorylation site of SRC leading to its abnormal activation and phosphorylation of cytoskeletal protein, paxillin. We demonstrated that MG-induced molecular changes could be reversed by pharmacological inhibitors of SHP-2 and SRC and by genetic depletion of SHP-2. Finally, a SHP-2 inhibitor completely reversed the dysfunction of monocytes isolated from DM patients and db/db mice. In conclusion, we identified SHP-2 as a hitherto unknown target for improving monocyte function in diabetes. This opens novel perspectives for treating diabetic complications associated with impaired monocyte function.

The regulation of miRNAs by reconstituted high-density lipoproteins in diabetes-impaired angiogenesis

Diabetic vascular complications are associated with impaired ischaemia-driven angiogenesis. We recently found that reconstituted high-density lipoproteins (rHDL) rescue diabetes-impaired angiogenesis. microRNAs (miRNAs) regulate angiogenesis and are transported within HDL to sites of injury/repair. The role of miRNAs in the rescue of diabetes-impaired angiogenesis by rHDL is unknown. Using a miRNA array, we found that rHDL inhibits hsa-miR-181c-5p expression in vitro and using a hsa-miR-181c-5p mimic and antimiR identify a novel anti-angiogenic role for miR-181c-5p. miRNA expression was tracked over time post-hindlimb ischaemic induction in diabetic mice. Early post-ischaemia when angiogenesis is important, rHDL suppressed hindlimb mmu-miR-181c-5p. mmu-miR-181c-5p was not detected in the plasma or within HDL, suggesting rHDL specifically targets mmu-miR-181c-5p at the ischaemic site. Three known angiogenic miRNAs (mmu-miR-223-3p, mmu-miR-27b-3p, mmu-miR-92a-3p) were elevated in the HDL fraction of diabetic rHDL-infused mice early post-ischaemia. This was accompanied by a decrease in plasma levels. Only mmu-miR-223-3p levels were elevated in the hindlimb 3 days post-ischaemia, indicating that rHDL regulates mmu-miR-223-3p in a time-dependent and site-specific manner. The early regulation of miRNAs, particularly miR-181c-5p, may underpin the rescue of diabetes-impaired angiogenesis by rHDL and has implications for the treatment of diabetes-related vascular complications.

Streptozotocin‑induced diabetic mice exhibit reduced experimental choroidal neovascularization but not corneal neovascularization

The present study aimed to investigate the effects of diabetes mellitus (DM) on the generation of experimental corneal neovascularization (CrNV) and choroidal neovascularization (ChNV). Diabetes was induced in mice by intraperitoneal injection of streptozotocin (STZ). Experimental CrNV and ChNV were induced by alkali injury and laser photocoagulation, respectively. CrNV and ChNV were compared between the STZ‑induced diabetic mice and control mice two weeks after injury. Relative expression of angiogenic factors was quantified by reverse transcription‑quantitative polymerase chain reaction, and progenitor cell or macrophage accumulation in the early phase following injury was examined by flow cytometric analysis. Compared with the alkali‑injured normal mice, the alkali‑injured diabetic mice (STZ‑induced) exhibited no significant difference in CrNV occurrence, whereas the laser‑injured diabetic mice exhibited significantly reduced levels of ChNV compared with those of the laser‑injured control animals. The laser‑induced intrachoroidal mRNA expression levels of angiogenic factors, including vascular endothelial growth factor, hypoxia‑induced factor‑1α, chemokine (C‑C motif) ligand 3, and stromal cell‑derived factor‑1α, were reduced in the laser‑injured diabetic mice when compared with laser‑injured control mice. Furthermore, the laser‑induced intrachoroidal infiltration of c‑Kit+ progenitor cells was impaired in the laser‑injured diabetic mice compared with the laser‑injured control mice. Overall, diabetes did not exert a significant effect on the generation of experimental CrNV. However, diabetes reduced laser‑induced ChNV through downregulation of intrachoroidal progenitor cell infiltration and angiogenic factor expression.

BMP-2 induces human mononuclear cell chemotaxis and adhesion and modulates monocyte-to-macrophage differentiation

Type 2 diabetes mellitus (T2DM) is a cardiovascular risk factor which leads to atherosclerosis, an inflammatory disease characterized by the infiltration of mononuclear cells in the vessel. Bone morphogenetic protein (BMP)‐2 is a cytokine which has been recently shown to be elevated in atherosclerosis and T2DM and to contribute to vascular inflammation. However, the role of BMP‐2 in the regulation of mononuclear cell function remains to be established. Herein, we demonstrate that BMP‐2 induced human monocyte chemotaxis via phosphoinositide 3 kinase and mitogen‐activated protein kinases. Inhibition of endogenous BMP‐2 signalling, by Noggin or a BMP receptor inhibitor, interfered with monocyte migration. Although BMP‐2 expression was increased in monocytes from T2DM patients, it could still stimulate their migration. Furthermore, BMP‐2 interfered with their differentiation into M2 macrophages. Finally, BMP‐2 both induced the adhesion of monocytes to fibronectin and endothelial cells (ECs), and promoted the adhesive properties of ECs, by increasing expression of adhesion and pro‐inflammatory molecules. Our data demonstrate that BMP‐2 could exert its pro‐inflammatory effects by inducing monocyte migration and adhesiveness to ECs and by interfering with the monocyte differentiation into M2 macrophages. Our findings provide novel insights into the mechanisms by which BMP‐2 may contribute to the development of atherosclerosis.

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Vascular Endothelial Growth Factor B and Its Signaling

In diabetes, compromised glucose utilization leads the heart to use FA almost exclusively for ATP generation. Chronically, this adaptation unfortunately leads to the conversion of FA to potentially toxic FA metabolites. Paired with increased formation of reactive oxygen species related to excessive mitochondrial oxidation of FA, can provoke cardiac cell death. To protect against this cell demise, intrinsic mechanisms must be available to the heart. Vascular endothelial growth factor B (VEGFB) may be one growth factor that plays an important role in protecting against heart failure. As a member of the VEGF family, initial studies with VEGFB focused on its role in angiogenesis. Surprisingly, VEGFB does not appear to play a direct role in angiogenesis under normal conditions or even when overexpressed, but has been implicated in influencing vascular growth indirectly by affecting VEGFA action. Intriguingly, VEGFB has also been shown to alter gene expression of proteins involved in cardiac metabolism and promote cell survival. Conversely, multiple models of heart failure, including diabetic cardiomyopathy, have indicated a significant drop in VEGFB. In this review, we will discuss the biology of VEGFB, and its relationship to diabetic cardiomyopathy.

Proangiogenic Effect of Metformin in Endothelial Cells Is via Upregulation of VEGFR1/2 and Their Signaling under Hyperglycemia-Hypoxia

Cardiovascular disease is the leading cause of morbidity/mortality worldwide. Metformin is the first therapy offering cardioprotection in type 2 diabetes and non-diabetic animals with unknown mechanism. We have shown that metformin improves angiogenesis via affecting expression of growth factors/angiogenic inhibitors in CD34⁺ cells under hyperglycemia-hypoxia. Now we studied the direct effect of physiological dose of metformin on human umbilical vein endothelial cells (HUVEC) under conditions mimicking hypoxia-hyperglycemia. HUVEC migration and apoptosis were studied after induction with euglycemia or hyperglycemia and/or CoCl₂ induced hypoxia in the presence or absence of metformin. HUVEC mRNA was assayed by whole transcript microarrays. Genes were confirmed by qRT-PCR, proteins by western blot, ELISA or flow cytometry. Metformin promoted HUVEC migration and inhibited apoptosis via upregulation of vascular endothelial growth factor (VEGF) receptors (VEGFR1/R2), fatty acid binding protein 4 (FABP4), ERK/mitogen-activated protein kinase signaling, chemokine ligand 8, lymphocyte antigen 96, Rho kinase 1 (ROCK1), matrix metalloproteinase 16 (MMP16) and tissue factor inhibitor-2 under hyperglycemia-chemical hypoxia. Therefore, metformin's dual effect in hyperglycemia-chemical hypoxia is mediated by direct effect on VEGFR1/R2 leading to activation of cell migration through MMP16 and ROCK1 upregulation, and inhibition of apoptosis by increase in phospho-ERK1/2 and FABP4, components of VEGF signaling cascades.

Functional convergence of Akt protein with VEGFR-1 in human endothelial progenitor cells exposed to sera from patient with type 2 diabetes mellitus

Diabetes mellitus type 2 predisposes patients to various microvascular complications. In the current experiment, the potent role of diabetes mellitus was investigated on the content of VEGFR-1, -2, Tie-1 and -2, and Akt in human endothelial progenitor cells. The gene expression profile of mTOR and Hedgehog signaling pathways were measured by PCR array. The possible crosstalk between RTKs, mTOR and Hedgehog signaling was also studied by bioinformatic analysis. Endothelial progenitor cells were incubated with serum from normal and diabetic for 7days. Compared to non-treated cells, diabetic serum-induced cell apoptosis (~2-fold) and prohibited cell migration toward bFGF (p<0.001). ELISA analysis showed that diabetes exposed cells had increased abundance of Tie-1, -2 and VEGFR-2 and reduced amount of VEGFR-1 (p<0.0001) in diabetic cells. Western blotting showed a marked reduction in the protein level of Akt after cells exposure to serum from diabetic subjects (p<0.0001). PCR array revealed a significant stimulation of both mTOR and Hedgehog signaling pathways in diabetic cells (p<0.05). According to data from bioinformatic datasets, we showed VEGFR-1, -2 and Tie-2, but not Tie-1, are master regulators of angiogenesis. There is a crosstalk between RTKs and mTOR signaling by involving P62, GABARAPL1, and HTT genes. It seems that physical interaction and co-expression of Akt decreased the level of VEGFR-1 in diabetic cells. Regarding data from the present experiment, diabetic serum contributed to uncontrolled induction of both mTOR and Hedgehog signaling in endothelial progenitor cells. Diabetes mellitus induces mTOR pathway by involving receptor tyrosine kinases while Hedgehog stimulation is independent of these receptors.

Assessment of Carotid Plaque Inflammation in Diabetic and Nondiabetic Patients-An Exploratory Ultrasmall Superparamagnetic Iron Oxide-Enhanced Magnetic Resonance Imaging Study

BACKGROUND

Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging enables the identification of inflammation within the atheroma, predominantly by USPIO uptake by macrophages present in atherosclerotic tissue. Diabetic patients, however, may have dysfunctional macrophage activity, which may affect utilization of USPIO in identifying plaque inflammation in this patient cohort.

METHODS

Fifteen diabetic and fifteen nondiabetic patients underwent USPIO-enhanced carotid MR imaging using 1.5T MR system. Pre- and post-USPIO carotid MR images were manually coregistered. The percentage decrease in the signal intensity after USPIO administration was calculated as a relative measure of the USPIO uptake.

RESULTS

Diabetic and nondiabetic patients had comparable demographics and comorbidities. The mean global, maximum quadrant, and maximum slice changes showing change in relative signal intensity as a result of USPIO administration were comparable for the two patient cohorts (P > .05).

CONCLUSIONS

USPIO can identify inflammatory burden with carotid atheroma in both diabetic and nondiabetic patients.

Cryopreservation of primary human monocytes does not negatively affect their functionality or their ability to be labelled with radionuclides: basis for molecular imaging and cell therapy

Background

Circulating white blood cells crucially contribute to maintenance and repair of solid organs. Therefore, certain cell populations such as monocytes are attractive targets for use in molecular imaging and cell imaging, e.g. after labelling with radionuclides, as well as for cell therapies. However, the preparation of monocytes may require freezing and thawing to preserve cells for timely and standardised applications. Additional modifications of these cells such as radioisotope labelling are necessary prior to their application in vivo. We therefore tested the hypothesis whether cryopreservation of freshly isolated circulating human monocytes affects their functional phenotype or their suitability for radionuclide labelling.

Results

CD14+CD16− monocytes were isolated from human peripheral blood. They were either directly used for cellular assays and labelling or frozen down using cryoprotectants. In the latter case, cells were thawed prior to further use and analysed for survival, chemotactic responses to various growth factors and adhesion on endothelial cells. In addition, both fresh and cryopreserved monocytes were labelled with radiotracers followed by assessment of survival and chemotactic responses. In all functional assays performed, cryopreserved monocytes did not significantly differ from freshly isolated monocytes with regard to their functionality. Cryopreservation did not affect cell survival. There was no effect on the chemotactic response of monocytes towards different growth factors. Likewise, adhesion properties remained unchanged following cryopreservation. Moreover, the labelling efficiency was similar for freshly isolated and cryopreserved monocytes. Labelling did not negatively affect monocyte survival and function.

Conclusions

Our data indicate that cryopreservation of freshly isolated human primary monocytes is feasible and does not negatively affect their functionality when used for labelling and functional assessment.

High-Density Lipoproteins Rescue Diabetes-Impaired Angiogenesis via Scavenger Receptor Class B Type I

Disordered neovascularization and impaired wound healing are important contributors to diabetic vascular complications. We recently showed that high-density lipoproteins (HDLs) enhance ischemia-mediated neovascularization, and mounting evidence suggests HDL have antidiabetic properties. We therefore hypothesized that HDL rescue diabetes-impaired neovascularization. Streptozotocin-induced diabetic mice had reduced blood flow recovery and neovessel formation in a hindlimb ischemia model compared with nondiabetic mice. Reconstituted HDL (rHDL) infusions in diabetic mice restored blood flow recovery and capillary density to nondiabetic levels. Topical rHDL application rescued diabetes-impaired wound closure, wound angiogenesis, and capillary density. In vitro, rHDL increased key mediators involved in hypoxia-inducible factor-1α (HIF-1α) stabilization, including the phosphoinositide 3-kinase/Akt pathway, Siah1, and Siah2, and suppressed the prolyl hydroxylases (PHD) 2 and PHD3. rHDL rescued high glucose-induced impairment of tubulogenesis and vascular endothelial growth factor (VEGF) A protein production, a finding associated with enhanced phosphorylation of proangiogenic mediators VEGF receptor 2 and endothelial nitric oxide synthase. Siah1/2 small interfering RNA knockdown confirmed the importance of HIF-1α stability in mediating rHDL action. Lentiviral short hairpin RNA knockdown of scavenger receptor class B type I (SR-BI) in vitro and SR-BI(-/-) diabetic mice in vivo attenuated rHDL rescue of diabetes-impaired angiogenesis, indicating a key role for SR-BI. These findings provide a greater understanding of the vascular biological effects of HDL, with potential therapeutic implications for diabetic vascular complications.

Impact of type 2 diabetes on the plasma levels of vascular endothelial growth factor and its soluble receptors type 1 and type 2 in patients with peripheral arterial disease

OBJECTIVE

Type 2 diabetes coexistent with lower extremity artery disease (peripheral arterial disease (PAD)) can be observed in numerous patients. The mechanism compensating for ischemia and contributing to healing is angiogenesis-the process of forming new blood vessels. The purpose of this study was to assess the likely impact of type 2 diabetes on the plasma levels of proangiogenic factor (vascular endothelial growth factor A (VEGF-A)) and angiogenesis inhibitors (soluble VEGF receptors type 1 and type 2 (sVEGFR-1 and sVEGFR-2)) in patients with PAD.

METHODS

Among 46 patients with PAD under pharmacological therapy (non-invasive), we identified, based on medical history, a subgroup with coexistent type 2 diabetes (PAD-DM2+, n=15) and without diabetes (PAD-DM2-, n=31). The control group consisted of 30 healthy subjects. Plasma levels of VEGF-A, sVEGFR-1, and sVEGFR-2 were measured using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The subgroups of PAD-DM2+ and PAD-DM2- revealed significantly higher concentrations of VEGF-A (P=0.000 007 and P=0.000 000 1, respectively) and significantly lower sVEGFR-2 levels (P=0.02 and P=0.000 01, respectively), when compared with the control group. Patients with PAD and coexistent diabetes tended to have a lower level of VEGF-A and higher levels of sVEGFR-1 and sVEGFR-2 comparable with non-diabetic patients.

CONCLUSIONS

The coexistence of type 2 diabetes and PAD is demonstrated by a tendency to a lower plasma level of proangiogenic factor (VEGF-A) and higher levels of angiogenesis inhibitors (sVEGFR-1 and sVEGFR-2) at the same time. Regardless of the coexistence of type 2 diabetes, hypoxia appears to be a crucial factor stimulating the processes of angiogenesis in PAD patients comparable with healthy individuals, whereas hyperglycemia may have a negative impact on angiogenesis in lower limbs.

Targeted Expression of Catalase to Mitochondria Protects Against Ischemic Myopathy in High-Fat Diet-Fed Mice

Patients with type 2 diabetes respond poorly to treatments for peripheral arterial disease (PAD) and are more likely to present with the most severe manifestation of the disease, critical limb ischemia. The underlying mechanisms linking type 2 diabetes and the severity of PAD manifestation are not well understood. We sought to test whether diet-induced mitochondrial dysfunction and oxidative stress would increase the susceptibility of the peripheral limb to hindlimb ischemia (HLI). Six weeks of high-fat diet (HFD) in C57BL/6 mice was insufficient to alter skeletal muscle mitochondrial content and respiratory function or the size of ischemic lesion after HLI, despite reducing blood flow. However, 16 weeks of HFD similarly decreased ischemic limb blood flow, but also exacerbated limb tissue necrosis, increased the myopathic lesion size, reduced muscle regeneration, attenuated muscle function, and exacerbated ischemic mitochondrial dysfunction. Mechanistically, mitochondrial-targeted overexpression of catalase prevented the HFD-induced ischemic limb necrosis, myopathy, and mitochondrial dysfunction, despite no improvement in limb blood flow. These findings demonstrate that skeletal muscle mitochondria are a critical pathological link between type 2 diabetes and PAD. Furthermore, therapeutically targeting mitochondria and oxidant burden is an effective strategy to alleviate tissue loss and ischemic myopathy during PAD.

Collateral Growth in the Peripheral Circulation: A Review

Arterial occlusive diseases are a major cause of morbidity and death in the United States. The enlargement of pre-existing vessels, which bypass the site of arterial occlusion, provide a natural way for the body to compensate for such obstructions. Individuals differ in their capacity to develop collateral vessels. In recent years much attention has been focused upon therapy to promote collateral development, primarily using individual growth factors. Such studies have had mixed results. Persistent controversies exist regarding the initiating stimuli, the processes involved in enlargement, the specific vessels that should be targeted, and the most appropriate terminology. Consequently, it is now recognized that more research is needed to extend our knowledge of the complex process of collateral growth. This basic science review addresses five questions essential in understanding current problems in collateral growth research and the development of therapeutic interventions.

Role of MicroRNA 126 in screening, diagnosis, and prognosis of diabetic patients in Egypt

MicroRNAs (miRNAs), family of non-coding small RNAs, play a vital role in the regulation of blood glucose level. We aimed to investigate the relation of serum miRNA-126 expression with impaired glucose tolerance as well as type 2 diabetes mellitus (T2DM) patients with and without complications. One hundred healthy controls, eighty-six patients with IGT, and one hundred patients with T2DM were recruited in this study. Serum miRNA-126 expression was assessed by quantitative real-time polymerase chain reaction. We found a significant decrease of serum miRNA-126 expression between IGT patients as well as diabetic patients when both compared with controls and between diabetic patients compared to IGT patients. A significant decrease of serum miRNA-126 expression was detected in diabetic patients with complications compared to those without evident complications especially those with diabetic macrovascular complications and diabetic retinopathy. Serum microRNA-126 expression could be a good marker for diagnosis of IGT and T2DM as well as for monitoring the outcomes of such disease. © 2016 IUBMB Life, 68(6):452-458, 2016.

High-glucose environment increased thrombospondin-1 expression in keratinocytes via DNA hypomethylation

Diabetes is an important health issue because of its increasing prevalence and association with impaired wound healing. Epidermal keratinocytes with overexpressed antiangiogenic molecule thrombospondin-1 (TSP1) have been shown to impair proper wound healing. This study examined the potential involvement of keratinocyte-derived TSP1 on diabetic wound healing. Cultured human keratinocytes and diabetic rat model were used to evaluate the effect of high-glucose environment on TSP1 expression in epidermal keratinocytes, and the molecular mechanisms involved in the process were also studied. We demonstrated that high-glucose environment increased TSP1 expression in keratinocytes. In addition, increased oxidative stress induced DNA hypomethylation at the TSP1 promoter region in keratinocytes exposed to high-glucose environment. Similar findings were found in our diabetic rat model. Early antioxidant administration normalized TSP1 expression and global DNA methylation status in diabetic rat skin and improved wound healing in vivo. Because oxidative stress contributed to TSP1 DNA hypomethylation, early recognition of diabetic condition and timely administration of antioxidant are logical approaches to reduce complications associated with diabetes as alterations in epigenome may not be reversible by controlling glucose levels during the later stages of disease course.

Collateral Circulation in Chronic Total Occlusions – an interventional perspective

Human coronary collaterals are inter-coronary communications that are believed to be present from birth. In the presence of chronic total occlusions, recruitment of flow via these collateral anastomoses to the arterial segment distal to occlusion provide an alternative source of blood flow to the myocardial segment at risk. This mitigates the ischemic injury. Clinical outcome of coronary occlusion ie. severity of myocardial infarction/ischemia, impairment of cardiac function and possibly survival depends not only on the acuity of the occlusion, extent of jeopardized myocardium, duration of ischemia but also to the adequacy of collateral circulation. Adequacy of collateral circulation can be assessed by various methods. These coronary collateral channels have been used successfully as a retrograde access route for percutaneous recanalization of chronic total occlusions. Factors that promote angiogenesis and further collateral remodeling ie. arteriogenesis have been identified. Promotion of collateral growth as a therapeutic target in patients with no suitable revascularization option is an exciting proposal.

Human mesenchymal stem cells alter the gene profile of monocytes from patients with Type 2 diabetes and end-stage renal disease

AIM

Macrophage infiltration contributes to the pathogenesis of Type 2 diabetes. Mesenchymal stem cells (MSCs) possess immunomodulatory properties, making them an ideal candidate for therapeutic intervention. This study investigated whether MSCs can modulate the phenotype of monocytes isolated from Type 2 diabetic patients with end-stage renal disease.

MATERIALS & METHODS

Monocytes from control (n = 4) and Type 2 diabetic patients with end-stage renal disease (n = 5) were assessed using flow cytometry and microarray profiling, following 48 h of co-culture with MSCs.

RESULTS

Control subjects had a greater proportion of CD14(++)CD16(-) monocytes while diabetic patients had a higher proportion of CD14(++)CD16(+) and CD14(+)CD16(++) monocytes. MSCs promoted the proliferation of monocytes isolated from diabetic patients, reduced HLA-DR expression in both groups and promoted the expression of anti-inflammatory genes.

CONCLUSION

MSC-derived factors alter the polarization of monocytes isolated from healthy and diabetic subjects toward an M2 phenotype.

The Anti-Inflammatory and Antibacterial Action of Nanocrystalline Silver and Manuka Honey on the Molecular Alternation of Diabetic Foot Ulcer: A Comprehensive Literature Review

Honey and silver have been used since ancient times for treating wounds. Their widespread clinical application has attracted attention in light of the increasing prevalence of antibiotic-resistant bacteria. While there have been a number of studies exploring the anti-inflammatory and antibacterial effects of manuka honey and nanocrystalline silver, their advantages and limitations with regard to the treatment of chronic wounds remain a subject of debate. The aim of this paper is to examine the evidence on the use of nanocrystalline silver and manuka honey for treating diabetic foot ulcers through a critical and comprehensive review of in vitro studies, animal studies, and in vivo studies. The findings from the in vitro and animal studies suggest that both agents have effective antibacterial actions. Their anti-inflammatory action and related impact on wound healing are unclear. Besides, there is no evidence to suggest that any topical agent is more effective for use in treating diabetic foot ulcer. Overall, high-quality, clinical human studies supported by findings from the molecular science on the use of manuka honey or nanocrystalline silver are lacking. There is a need for rigorously designed human clinical studies on the subject to fill this knowledge gap and guide clinical practice.

Collaterals: Implications in cerebral ischemic diseases and therapeutic interventions

Despite the tremendous progress made in the treatment of cerebrovascular occlusive diseases, many patients suffering from ischemic brain injury still experience dismal outcomes. Although rehabilitation contributes to post-stroke functional recovery, there is no doubt that interventions that promote the restoration of blood supply are proven to minimize ischemic injury and improve recovery. In response to the acutely decreased blood perfusion during arterial occlusion, arteriogenesis, the compensation of blood flow through the collateral circulation during arterial obstructive diseases can act not only in a timely fashion but also much more efficiently compared to angiogenesis, the sprouting of new capillaries, and a mechanism occurring in a delayed fashion while increases the total resistance of the vascular bed of the affected territory. Interestingly, despite the vast differences between the two vascular remodeling mechanisms, some crucial growth factors and cytokines involved in angiogenesis are also required for arteriogenesis. Understanding the mechanisms underlying vascular remodeling after ischemic brain injury is a critical step towards the development of effective therapies for ischemic stroke. The present article will discuss our current views in vascular remodeling acutely after brain ischemia, namely arteriogenesis, and some relevant clinical therapies available on the horizon in augmenting collateral flow that hold promise in treating ischemic brain injury. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

The association of plasma vitamin A and E levels with coronary collateral circulation

OBJECTIVE

To investigate if plasma levels of vitamin A and E have an association with coronary collateral development.

METHODS

A total of 189 patients who underwent coronary angiography and had total occlusion in at least one major epicardial coronary artery were enrolled in the study. To classify coronary collateral circulation (CCC), the Rentrop scoring system was used. Patients were classified as having poor CCC (Rentrop grades 0-1) or good CCC (Rentrop grades 2-3), and all patients were also screened for hypertension, hypercholesterolemia, diabetes, and smoking history.

RESULTS

There were no differences in plasma vitamin A and E levels between the two groups (vitamin A: 2.37 ± 0.65 vs. 2.35 ± 0.78, p = 0.253; vitamin E: 47.1 ± 12.8 vs. 44.6 ± 15.1, p = 0.082), and plasma vitamin A and E levels were not associated with CCC. Serum high-sensitivity C-reactive protein (hs-CRP) levels were significantly higher in patients with poor CCC (4.68 ± 2.52 vs. 3.89 ± 1.78, p = 0.001). The higher frequency of diabetes and higher serum hs-CRP levels were found to be an independent predictor for poor CCC (odds ratio = 2.44, p = 0.006; odds ratio = 1.24, p = 0.007, respectively). And a higher frequency of total occluded RCA was found to be a positive predictor for good CCC (odds ratio = 2.36, p = 0.06) in a multivariate logistic regression analysis.

CONCLUSIONS

We found that serum hs-CRP levels, presence of diabetes, and total occlusion of RCA have an effect on coronary collateral development. We found no correlation between plasma vitamin A and E levels and CCC.