Calcium dobesilate inhibits the alterations in tight junction proteins and leukocyte adhesion to retinal endothelial cells induced by diabetes

The effectiveness and safety of Chinese patent medicines plus calcium dobesilate for the treatment of diabetic retinopathy: A network meta-analysis

Chinese patent medicines (CPMs) are commonly prescribed by clinicians in China as adjuvant therapy for diabetic retinopathy (DR). The study of network meta-analysis (NMA) aims to compare the effectiveness and safety of three CPMs plus calcium dobesilate (CD) for DR, and to explore optimal CPM for treatment of DR. Methods. Bayesian network meta-analyses were designed to evaluate the safety and effectiveness of different CPMs for the treatment of DR. Systematic Review Registration CRD42022323996. Results. A total of 23 eligible RCTs involving 1824 patients were enrolled. Compared with CD alone, Cmpound Danshen Dripping Pills (DS) + CD or Qiming Granule (QM) + CD considerably enhanced best corrected visual acuity (BCVA); DS + CD or Compound Xueshuantong Capsule (XST) + CD significantly reduced macular thickness; CPMs + CD significantly reduced the level of VEGF. In addition, DS + CD or XST + CD over QM + CD in reducing macular thickness. As for the adverse events, the differences across different CPMs were not statistically significant, and no statistically significant difference between the CPMs and CD. Conclusion. DS plus CD or QM plus CD may be better effective in improving BCVA; DS plus CD or XST plus CD may be better effective in reducing macular thickness; The combination therapy all may be better effective in reducing the level of VEGF. As for safety profile that CPMs plus CD did not increase the incidence of adverse events. The results of this study might support DS as a relatively prior adjuvant therapy option for patients with DR.

Knockdown of ChREBP ameliorates retinal microvascular endothelial cell injury and angiogenic responses in diabetic retinopathy

PURPOSE

To examine whether and how carbohydrate response element-binding protein (ChREBP) plays a role in diabetic retinopathy.

METHODS

Western blotting was used to detect ChREBP expression and location following high glucose stimulation of Human Retinal Microvascular Endothelial Cells (HRMECs). Flow cytometry, TUNEL staining, and western blotting were used to evaluate apoptosis following ChREBP siRNA silencing. Cell scratch, transwell migration, and tube formation assays were used to determine cell migration and angiogenesis. Diabetic models for wild-type (WT) and ChREBP knockout (ChKO) mice were developed. Retinas of WT and ChKO animals were cultivated in vitro with vascular endothelial growth factor + high glucose to assess neovascular development.

RESULTS

ChREBP gene knockdown inhibited thioredoxin-interacting protein and NOD-like receptor family pyrin domain containing protein 3 expression in HRMECs, which was caused by high glucose stimulation, reduced apoptosis, hindered migration, and tube formation, and repressed AKT/mTOR signaling pathway activation. Compared with WT mice, ChKO mice showed suppressed high glucose-induced alterations in retinal structure, alleviated retinal vascular leakage, and reduced retinal neovascularization.

CONCLUSIONS

ChREBP deficiency decreased high glucose-induced apoptosis, migration, and tube formation in HRMECs as well as structural and angiogenic responses in the mouse retina; thus, it is a potential therapeutic target for diabetic retinopathy.

CircRNA SCAR Improves High-Glucose-Induced Mitochondrial Dysfunction and Permeability Damage in Retinal Microvascular Endothelial Cells

This study was designed to assess the role and mechanism of circRNA SCAR in human retinal microvascular endothelial cells (hRMVECs) treated with high glucose. Quantitative real-time polymerase chain reaction (qRT-PCR) and cell counting kit 8 (CCK-8) were used to detect the effects of different concentrations of glucose on circRNA SCAR expression and cell proliferation in hRMVECs. Cell viability, levels of oxygen species (ROS), malondialdehyde (MDA) and adenosine triphosphate (ATP), as well as activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the transfected hRMVECs in each group were detected using CCK-8 and their corresponding detection kits. Changes in mtDNA copy number in high-glucose-induced hRMVECs were observed by qRT-PCR. Additionally, western blot was applied to detect effect of overexpressing circRNA SCAR on the expression levels of mitochondrial function-related proteins (Drp1 and Fis1) and cell permeability-related proteins (claudin-5, occludin and ZO-1) in hRMVECs under high-glucose concentration. According to experimental results, high glucose significantly downregulated circRNA SCAR expression and inhibited cell proliferation in hRMVECs. Instead, overexpression of this circRNA SCAR promoted cell proliferation, reduced levels of ROS, MDA and ATP, and increased SOD and CAT activities in hRMVECs under high-glucose concentration. Also, circRNA SCAR overexpression reversed the high-glucose-induced decrease in mtDNA copy number as well as, high-glucose-induced upregulation of Drp1 and Fis1 protein expression and downregulation of claudin-5, occludin and ZO-1 protein expression in hRMVECs. In summary, circRNA SCAR promotes the proliferation of hRMVECs under high-glucose concentration, alleviates oxidative stress induced by high glucose, and improves mitochondrial function and permeability damage.

Calcium dobesilate prevents PLD-induced hand-foot syndrome by alleviating capillary endothelial tight junction injury via the HA/CD44 pathway

Pegylated liposomal doxorubicin (PLD) has excellent therapeutic efficacy in the treatment of cancers, but can cause serious adverse reactions such as hand-foot syndrome (HFS). Our previous research suggests that both PLD-induced HFS may be associated with injury to tight junctions (TJs) in the skin and that calcium dobesilate (CaD) can alleviate HFS. However, the underlying molecular mechanism is not well understood. Here, we created an in vitro PLD-treated model using Human Microvascular Endothelial Cell line-1 (HMEC-1) and an in vivo HFS rat model to investigate the underlying pathways. Treatment with PLD increased the expression of HYAL-1, CD44, and hyaluronic acid (HA) concentration, while reducing ZO-1 and Claudin-5 expression. Moreover, PLD treatment induced the degradation of higher molecular weight HA to its lower molecular weight counterpart, elevating the permeability of both HEMC-1 cell membranes and rat paw skin capillaries. AD-01 (CD44 inhibitor) inhibited the effect of PLD on the expression of ZO-1 and Claudin-5. Furthermore, CaD treatment suppressed the expression of HYAL-1 and CD44, mitigated HA degradation, and enhanced the expression of ZO-1 and Claudin-5. This resulted in decreased permeability in HEMC-1 cells and rat skin capillaries. In summary, our data suggest that PLD may promote the destruction of TJs via the HA/CD44 pathway, thereby leading to HFS through increased skin permeability and exacerbated doxorubicin extravasation. Moreover, CaD can inhibit this pathway, offering a potential therapeutic avenue to alleviate HFS.

Retinal Cell Damage in Diabetic Retinopathy

Diabetic retinopathy (DR), the most common microvascular complication that occurs in diabetes mellitus (DM), is the leading cause of vision loss in working-age adults. The prevalence of diabetic retinopathy is approximately 30% of the diabetic population and untreated DR can eventually cause blindness. For decades, diabetic retinopathy was considered a microvascular complication and clinically staged by its vascular manifestations. In recent years, emerging evidence has shown that diabetic retinopathy causes early neuronal dysfunction and neurodegeneration that may precede vascular pathology and affect retinal neurons as well as glial cells. This knowledge leads to new therapeutic strategies aiming to prevent dysfunction of retinal neurons at the early stage of DR. Early detection and timely treatment to protect retinal neurons are critical to preventing visual loss in DR. This review provides an overview of DR and the structural and functional changes associated with DR, and discusses neuronal degeneration during diabetic retinopathy, the mechanisms underlying retinal neurodegeneration and microvascular complications, and perspectives on current and future clinic therapies.

Exploring Pro-Inflammatory Immunological Mediators: Unraveling the Mechanisms of Neuroinflammation in Lysosomal Storage Diseases

Lysosomal storage diseases are a group of rare and ultra-rare genetic disorders caused by defects in specific genes that result in the accumulation of toxic substances in the lysosome. This excess accumulation of such cellular materials stimulates the activation of immune and neurological cells, leading to neuroinflammation and neurodegeneration in the central and peripheral nervous systems. Examples of lysosomal storage diseases include Gaucher, Fabry, Tay–Sachs, Sandhoff, and Wolman diseases. These diseases are characterized by the accumulation of various substrates, such as glucosylceramide, globotriaosylceramide, ganglioside GM2, sphingomyelin, ceramide, and triglycerides, in the affected cells. The resulting pro-inflammatory environment leads to the generation of pro-inflammatory cytokines, chemokines, growth factors, and several components of complement cascades, which contribute to the progressive neurodegeneration seen in these diseases. In this study, we provide an overview of the genetic defects associated with lysosomal storage diseases and their impact on the induction of neuro-immune inflammation. By understanding the underlying mechanisms behind these diseases, we aim to provide new insights into potential biomarkers and therapeutic targets for monitoring and managing the severity of these diseases. In conclusion, lysosomal storage diseases present a complex challenge for patients and clinicians, but this study offers a comprehensive overview of the impact of these diseases on the central and peripheral nervous systems and provides a foundation for further research into potential treatments.

Immunological consequences of compromised ocular immune privilege accelerate retinal degeneration in retinitis pigmentosa

Background

Retinitis pigmentosa (RP) is a hereditary retinal disease which leads to visual impairment. The onset and progression of RP has physiological consequences that affects the ocular environment. Some of the key non-genetic factors which hasten the retinal degeneration in RP include oxidative stress, hypoxia and ocular inflammation. In this study, we investigated the status of the ocular immune privilege during retinal degeneration and the effect of ocular immune changes on the peripheral immune system in RP. We assessed the peripheral blood mononuclear cell stimulation by retinal antigens and their immune response status in RP patients. Subsequently, we examined alterations in ocular immune privilege machineries which may contribute to ocular inflammation and disease progression in rd1 mouse model.

Results

In RP patients, we observed a suppressed anti-inflammatory response to self-retinal antigens, thereby indicating a deviated response to self-antigens. The ocular milieu in rd1 mouse model indicated a significant decrease in immune suppressive ligands and cytokine TGF-B1, and higher pro-inflammatory ocular protein levels. Further, blood–retinal-barrier breakdown due to decrease in the expression of tight junction proteins was observed. The retinal breach potentiated pro-inflammatory peripheral immune activation against retinal antigens and caused infiltration of the peripheral immune cells into the ocular tissue.

Conclusions

Our studies with RP patients and rd1 mouse model suggest that immunological consequences in RP is a contributing factor in the progression of retinal degeneration. The ocular inflammation in the RP alters the ocular immune privilege mechanisms and peripheral immune response. These aberrations in turn create an auto-reactive immune environment and accelerate retinal degeneration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02528-x.

The Effect of Diet and Lifestyle on the Course of Diabetic Retinopathy-A Review of the Literature

Diabetes is a major social problem. As shown by epidemiological studies, the world incidence of diabetes is increasing and so is the number of people suffering from its complications. Therefore, it is important to determine possible preventive tools. In the prevention of diabetic retinopathy, it is essential to control glycemia, lipid profile and blood pressure. This can be done not only by pharmacological treatment, but first of all by promoting a healthy lifestyle, changing dietary habits and increasing physical activity. In our work, we present a review of the literature to show that physical exercise and an adequate diet can significantly reduce the risk of diabetes and diabetic retinopathy.

TGR5 Activation Ameliorates Mitochondrial Homeostasis via Regulating the PKCδ/Drp1-HK2 Signaling in Diabetic Retinopathy

Background: Diabetic retinopathy (DR) is one of the most important microvascular diseases of diabetes. Our previous research demonstrated that bile acid G-protein-coupled membrane receptor (TGR5), a novel cell membrane receptor of bile acid, ameliorates the vascular endothelial cell dysfunction in DR. However, the precise mechanism leading to this alteration remains unknown. Thus, the mechanism of TGR5 in the progress of DR should be urgently explored.

Methods: In this study, we established high glucose (HG)-induced human retinal vascular endothelial cells (RMECs) and streptozotocin-induced DR rat in vitro and in vivo. The expression of TGR5 was interfered through the specific agonist or siRNA to study the effect of TGR5 on the function of endothelial cell in vitro. Western blot, immunofluorescence and fluorescent probes were used to explore how TGR5 regulated mitochondrial homeostasis and related molecular mechanism. The adeno-associated virus serotype 8-shTGR5 (AAV8-shTGR5) was performed to evaluate retinal dysfunction in vivo and further confirm the role of TGR5 in DR by HE staining, TUNEL staining, PAS staining and Evans Blue dye.

Results: We found that TGR5 activation alleviated HG-induced endothelial cell apoptosis by improving mitochondrial homeostasis. Additionally, TGR5 signaling reduced mitochondrial fission by suppressing the Ca²⁺-PKCδ/Drp1 signaling and enhanced mitophagy through the upregulation of the PINK1/Parkin signaling pathway. Furthermore, our result indicated that Drp1 inhibited mitophagy by facilitating the hexokinase (HK) 2 separation from the mitochondria and HK2-PINK1/Parkin signaling. In vivo, intraretinal microvascular abnormalities, including retinal vascular leakage, acellular capillaries and apoptosis, were poor in AAV8-shTGR5-treated group under DR, but this effect was reversed by pretreatment with the mitochondrial fission inhibitor Mdivi-1 or autophagy agonist Rapamycin.

Conclusion: Overall, our findings indicated that TGR5 inhibited mitochondrial fission and enhanced mitophagy in RMECs by regulating the PKCδ/Drp1-HK2 signaling pathway. These results revealed the molecular mechanisms underlying the protective effects of TGR5 and suggested that activation of TGR5 might be a potential therapeutic strategy for DR.

Calcium dobesilate ameliorates hepatorenal injury induced by carbon tetrachloride in mice

Objectives

Calcium dobesilate (CaD) has anti-oxidant, anti-inflammatory, and anti-apoptotic effects. In this study, the protective effects of CaD against hepatorenal damage induced by carbon tetrachloride (CCl₄) in mice were evaluated.

Materials and Methods

Thirty male mice were randomly divided into five groups: Control, CaD 100 mg/kg, CCl₄, CCl₄+CaD 50 mg/kg, and CCl₄+CaD 100 mg/kg. CaD (50 and 100 mg/kg) was administered orally once a day for 4 weeks. The liver and kidney indices (serum creatinine, blood urine nitrogen, alanine aminotransferase, and aspartate aminotransferase levels) were determined. Also, liver and kidney tissue oxidant/anti-oxidant markers (glutathione peroxidase, malondialdehyde, total anti-oxidant capacity, and superoxide dismutase) were measured. Cleaved caspase-3, Bax, cytochrome-c, and Bcl-2 protein levels were measured by immunoblotting method in the liver and kidney tissues. The liver and kidney histopathological changes were evaluated by the Hematoxylin and Eosin (H&E) staining method.

Results

CCl₄ induced significant oxidative stress and apoptosis in kidney and liver tissues that was concomitant with histopathological abnormalities in these organs in the CCl₄ group versus the control (P<0.05). However, CaD (100 mg/kg) could significantly improve the histopathological change in the liver and kidney tissues of CCl₄+CaD 100 mg/kg mice versus the CCl₄ group (P<0.05). In addition, CaD (100 mg/kg) attenuated the pro and anti-apoptotic markers in the liver and kidney tissues of CCl₄+CaD 100 mg/kg mice versus the CCl₄ group (P<0.05).

Conclusion

CaD (100 mg/kg) has a protective effect against hepatorenal injury induced by CCl₄ at least via its anti-apoptotic and anti-oxidant properties.

Calcium dobesilate alleviates renal dysfunction and inflammation by targeting nuclear factor kappa B (NF-κB) signaling in sepsis-associated acute kidney injury

Acute kidney injury (AKI) is a serious complication of sepsis that increases mortality and the risk of progression to chronic kidney disease. Oxidative stress and apoptosis are reported to exert critical function in the pathogenesis of sepsis-associated AKI. Calcium dobesilate (CaD) was reported to play a protective role in renal diseases. Therefore, we explored the antioxidant effect and potential mechanism of CaD in lipopolysaccharide (LPS)-induced AKI in mice. We evaluated renal function (blood urea nitrogen (BUN) and serum creatinine (SCr)), histopathology, oxidative stress (superoxide dismutase (SOD) and malondialdehyde (MDA)), inflammation cytokines, and apoptosis in kidneys of mice. The effect of CaD on NF-κB signaling was evaluated by Western blot. Our findings showed that CaD alleviated renal dysfunction and kidney injury, and also reversed upregulated MDA concentration and reduced SOD enzyme activity in AKI mice. Moreover, LPS-induced inflammatory response was attenuated by CaD. CaD treatment also reduced the apoptosis evoked by LPS. Additionally, CaD downregulated phosphorylation of nuclear factor kappa B (NF-κB) signaling components in LPS mice. Conclusively, CaD alleviates renal dysfunction and inflammation by targeting NF-κB signaling in sepsis-associated AKI.

Endostatin Inhibits Blood-Retinal Barrier Breakdown in Diabetic Rats by Increasing the Expression of ICAM-1 and VCAM-1 and Decreasing the Expression of VEGF

Objective

Endostatin has become the strongest endogenous angiogenesis inhibitor due to suppressing VEGF expression. The purpose of this study was to assess the impact of endostatin on the blood-retinal barrier (BRB) in diabetic rats.

Methods

SD rats were induced to develop diabetes by streptozotocin, and endostatin was administrated by intravitreal injection. The body weight, the level of blood glucose, the expressions of C-reactive protein (CRP), adhesion molecules intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), junction proteins (occludin, claudin-5, and zonula occluden-1), and VEGF were measured in rats' retinas of diabetes. The BRB breakdown was evaluated using Evans blue.

Results

The level of CRP and adhesion molecules (ICAM-1 and VCAM-1) was increased in retinas of diabetic rats, while endostatin significantly inhibited the upregulation of these. Diabetes increased the BRB permeability and retinal thickness. Diabetes also decreased the levels of occludin, claudin-5, and ZO-1 in retinals. These changes were inhibited by endostatin treatment. Upregulation of vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β), and protein kinase C- (PKC-) β2 was also reversed by endostatin in retinas of diabetic rats.

Conclusions

Endostatin provides protection against diabetic retinopathy, which may involve its barrier-enhancing effects.

Effect of Chinese Patent Medicines on Ocular Fundus Signs and Vision in Calcium Dobesilate-Treated Persons With Non-Proliferative Diabetic Retinopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Diabetic retinopathy (DR), one of the commonest microvascular complications in diabetic patients, is featured by a series of fundus lesions. Conventional Western medicine therapies for DR are always with modest treatment outcome. This paper is to assess the ocular fundus signs, vision and safety of Chinese patent medicines (CPMs) as an add-on treatment for DR.

METHOD

7 electronic databases were searched to determine eligible trials. Randomized controlled trials (RCTs) of non-proliferative diabetic retinopathy (NPDR) in which the intervention group received CPMs combined with calcium dobesilate (CD), and the control group received only CD were included for analysis. Two reviewers extracted the data independently. Results expressing as mean differences (MD) and relative risks (RR) were analyzed with a fixed-effects or random-effects models.

RESULTS

19 RCTs involved 1568 participants with 1622 eyes met our inclusion criteria. The results suggested that compared with CD alone, CPMs plus CD for NPDR was superior at reducing the microaneurysm volume (MD -3.37; 95% confidence interval [CI], -3.59 to -3.14), microaneurysm counts (MD -2.29; 95%CI -2.97 to -1.61), hemorrhage area (MD -0.79; 95%CI -0.83 to -0.75), and macular thickness (MD -59.72; 95%CI -63.24 to -56.20). Participants in CPMs plus CD group also achieved a better vision. No obvious adverse events occurred.

CONCLUSION

CPMs as an add-on therapy for NPDR have additional benefits and be generally safe. This meta-analysis demonstrated that CPMs combined with CD could improve retinal microaneurysm, hemorrhage, macular thickness, visual acuity, fasting blood glucose (FBG), and glycosylated hemoglobin (HbAlc) compared with CD alone. Further studies are needed to provide more conclusive evidence.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO https://www.crd.york.ac.uk/prospero/, identifier CRD42021257999.

Effect of Chinese herbal compounds on ocular fundus signs and vision in conventional treated-persons with non-proliferative diabetic retinopathy: A systematic review and meta-analysis

BACKGROUND

Changes in fundus signs and loss of visual acuity are an important basis for screening and treating diabetic patients with retinopathy, and conventional Western medicine is moderately effective in treating diabetic retinopathy(DR),To systematically evaluate the effectiveness and safety of Chinese herbal compounds(CHCs) in the combined treatment of diabetic retinopathy.

METHOD

Six electronic databases, including PubMed, were searched to screen eligible literature. Randomized controlled trials of non-proliferative diabetic retinopathy(NPDR) were included, in which the control group was treated with conventional Western-based drugs or retinal laser photocoagulation, and the intervention group was treated with CHCs in combination based on the control group.The Cochrane Risk of Bias Assessment Tool was used to evaluate the quality of the literature, and the RevMan 5.4 software was used for statistical analysis.

RESULTS

Compared with Conventional group alone,CHCs group was superior at improving clinical efficacy [RR=1.29, 95%CI=(1.23, 1.36),P<0.01] and best corrected visual acuity(BCVA) [MD=0.10,95%CI=(0.09,0.12),P<0.01],it was also superior at reducing the number of microangiomas [MD=-2.37, 95%CI=(-3.26, -1.49),P<0.01], microangioma volume [MD=-4.72, 95%CI=(-5.14, -4.29), P<0.01], hemorrhagic spots [MD=-2.05, 95%CI=(-2.51,-1.59), P<0.01], hemorrhagic area [MD=-0.76, 95%CI=(-1.06, -0.47), P<0.01], hard exudates [MD= -1.86, 95%CI=(-2.43, -1.28), P<0.01], cotton lint spots [MD= -0.93, 95%CI= (-1.31, -0.55), P<0.01], central macular thickness(CMT) [SMD=-1.52, 95%CI=(-1.85, -1.19),P<0.01], Chinese medicine evidence score [SMD=-1.33,95%CI=(-1.58, -1.08),P<0.01], fasting blood glucose (FBG) [SMD=-0.47, 95%CI=(-0.61,-0.33),P<0.01], 2h postprandial blood glucose(2hPBG) [SMD=-0.87, 95% CI=(-1.06, -0.67), P<0.01], glycosylated hemoglobin (HbAlc) [SMD=-0.76, 95%CI=(-1.16, -0.3),P<0.01], total cholesterol(TC) [SMD=-0.33,95%CI=(-0.51,-0.16),P<0.01],and CHCs group with less adverse events occurred [RR=0.46, 95%CI=(0.29, 0.74),P<0.01].

CONCLUSION

CHCs combined with conventional medicine for NPDR has better clinical efficacy and higher safety, but the above findings need further validation in more large sample, multicenter, and low-bias RCTs due to the limitation of the quality and quantity of included literature.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD42022342137.

Calcium Dobesilate Modulates PKCδ-NADPH Oxidase- MAPK-NF-κB Signaling Pathway to Reduce CD14, TLR4, and MMP9 Expression during Monocyte-to-Macrophage Differentiation: Potential Therapeutic Implications for Atherosclerosis

Monocyte-to-macrophage differentiation results in the secretion of various inflammatory mediators and oxidative stress molecules necessary for atherosclerosis pathogenesis. Consequently, this differentiation represents a potential clinical target in atherosclerosis. Calcium dobesilate (CaD), an established vasoactive and angioprotective drug in experimental models of diabetic microvascular complications reduces oxidative stress and inhibits inflammation via diverse molecular targets; however, its effect on monocytes/macrophages is poorly understood. In this study, we investigated the anti-inflammatory mechanism of CaD during phorbol 12-myristate 13-acetate (PMA)-induced monocyte-to-macrophage differentiation in in vitro models of sepsis (LPS) and hyperglycemia, using THP-1 monocytic cell line. CaD significantly suppressed CD14, TLR4, and MMP9 expression and activity, lowering pro-inflammatory mediators, such as IL1β, TNFα, and MCP-1. The effects of CaD translated through to studies on primary human macrophages. CaD inhibited reactive oxygen species (ROS) generation, PKCδ, MAPK (ERK1/2 and p38) phosphorylation, NOX2/p47phox expression, and membrane translocation. We used hydrogen peroxide (H2O2) to mimic oxidative stress, demonstrating that CaD suppressed PKCδ activation via its ROS-scavenging properties. Taken together, we demonstrate for the first time that CaD suppresses CD14, TLR4, MMP9, and signature pro-inflammatory cytokines, in human macrophages, via the downregulation of PKCδ/NADPH oxidase/ROS/MAPK/NF-κB-dependent signaling pathways. Our data present novel mechanisms of how CaD alleviates metabolic and infectious inflammation.

Neurovascular Unit: A New Target for Treating Early Stages of Diabetic Retinopathy

The concept of diabetic retinopathy as a microvascular disease has evolved and is now considered a more complex diabetic complication in which neurovascular unit impairment plays an essential role and, therefore, can be considered as a main therapeutic target in the early stages of the disease. However, neurodegeneration is not always the apparent primary event in the natural story of diabetic retinopathy, and a phenotyping characterization is recommendable to identify those patients in whom neuroprotective treatment might be of benefit. In recent years, a myriad of treatments based on neuroprotection have been tested in experimental models, but more interestingly, there are drugs with a dual activity (neuroprotective and vasculotropic). In this review, the recent evidence concerning the therapeutic approaches targeting neurovascular unit impairment will be presented, along with a critical review of the scientific gaps and problems which remain to be overcome before our knowledge can be transferred to clinical practice.

Therapeutic effect of Keap1-Nrf2-ARE pathway-related drugs on age-related eye diseases through anti-oxidative stress

Age-related eye diseases, including cataract, glaucoma, diabetic retinopathy (DR), and age-related macular degeneration (AMD), are the leading causes of vision loss in the world. Several studies have shown that the occurrence and development of these diseases have an important relationship with oxidative stress in the eye. The Keap1-Nrf2-ARE pathway is a classical pathway that resists oxidative stress and inflammation in the body. This pathway is also active in the development of age-related eye diseases. A variety of drugs have been shown to treat age-related eye diseases through the Keap1-Nrf2-ARE (Kelch-like ECH-Associating protein 1- nuclear factor erythroid 2 related factor 2-antioxidant response element) pathway. This review describes the role of oxidative stress in the development of age-related eye diseases, the function and regulation of the Keap1-Nrf2-ARE pathway, and the therapeutic effects of drugs associated with this pathway on age-related eye diseases.

Effect of calcium dobesilate on retrobulbar blood flow and choroidal thickness in patients with non-proliferative diabetic retinopathy

INTRODUCTION

Diabetic retinopathy is one of the most common causes of blindness in work-aging adults and develops in one third of diabetic patients. Calcium dobesilate (CaD) treatment have protective effects on blood retinal barrier (BRB) and anti-oxidant as well as anti-inflammatory properties.

OBJECTIVES

To assess effects of CaD administration on retrobulbar blood flow and choroidal thickness in patients with diabetic retinopathy.

METHODS

In this quasi-experimental study, diabetic patients with diabetic retinopathy (DR) were recruited from Shahid Motahari and Poostchi ophthalmology clinic affiliated to Shiraz University of Medical Sciences. Patients were treated with CaD, 1 gr per day for seven days. Before and after CaD administration, retrobulbar blood flow and subfoveal choroidal thickness were assessed. Retrobulbar blood flow were evaluated by measuring peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) of ophthalmic artery (OA), central retinal artery (CRA) and short ciliary artery (SCA).

RESULTS

In this study, 26 DR patients with a mean age of 56.15 ± 8.93 years and mean diabetes mellitus duration of 15.04 ± 7.64 years were enrolled. Subfoveal choroidal thickness was significantly increased from 316.08 ± 61.69 to 327.81 ± 58.03 after CaD treatment (P value < 0.001). PSV of CRA and EDV of all arteries were significantly increased after CaD administration. In addition, RI of all arteries was significantly reduced after CaD treatment (P < 0.001).

CONCLUSION

CaD treatment may improve the ophthalmic blood flow and increase the subfoveal choroidal thickness in DR patients. These results may be suggestive of protective effects of CaD on endothelium function as well as microvascular circulation.

Protective Effect of Calcium Dobesilate on Induced AKI in Severely Burned Mice

BACKGROUND

Early acute kidney injury (AKI) predicts a high mortality rate in severely burned patients. However, the pathophysiology of early AKI induced by severe burn has not been well-defined. This study was designed to examine the protective effects of calcium dobesilate (CaD) against severe burn-induced early AKI in mice and explore the mechanism.

METHODS

The shaved backs of mice were immersed in 100°C water for 10 s to make severe burn (40% of the total body surface area). CD-57 male mice were randomly divided into sham, burn, burn + vehicle, and burn + CaD groups. Renal function, reactive oxygen species generation, tubular necrosis, and phosphorylation of mitogen-activated protein kinase, protein kinase B (Akt), and nuclear factor (NF)-κB were measured at 24 and 48 h after the burn. Renal histology, ELISA, qRT-PCR, and Western blotting were performed on the renal tissue of mice to examine the effects and mechanisms at 24 and 48 h after the burn.

RESULTS

Tubular damage, cast formation, and elevations of serum creatinine, BUN, and renal tissue kidney injury molecule 1 levels were all observed in the burned mice, and these were all alleviated in the mice with CaD treatment. In addition, the levels of oxidation-reduction potential and malondialdehyde were decreased, while the activities of the endogenous antioxidative enzymes were increased in the kidney tissues from the mice after CaD treatment. Furthermore, the activities of Akt, p38, extracellular sign-regulated kinase, Jun N-terminal kinase, and NF-κB signaling were increased in the kidney of burned mice and normalized after CaD treatment.

CONCLUSION

This study has established, for the first time, the protective effect of CaD against early AKI in severely burned mice. CaD may exert its protective effect through alleviating oxidative stress, apoptosis, and inflammation, as well as modulating some signaling pathways in the kidney.

Efficacy of calcium dobesilate in treating Chinese patients with mild-to-moderate non-proliferative diabetic retinopathy (CALM-DR): protocol for a single-blind, multicentre, 24-armed cluster-randomised, controlled trial

INTRODUCTION

Calcium dobesilate (CaD) has been used in the treatment of diabetic retinopathy (DR) due to its potential in protecting against retinal vascular damage. However, there is limited evidence exploring its efficacy in combating DR progression. This study is aimed at evaluating whether CaD could prevent DR progression into an advanced stage among Chinese patients with mild-to-moderate non-proliferative DR (NPDR).

METHODS AND ANALYSIS

This study is a single-blind, multicentre, cluster-randomised, controlled superiority trial. A total of 1272 patients with mild-to-moderate NPDR will be enrolled and randomly assigned at a 1:1 ratio into the control group (conventional treatment group) and the intervention group (conventional treatment plus CaD (500 mg three times per day) for 12 months). Patients will be followed at 1, 3, 6 and 12 months after randomisation and receiving treatments, with the severity of DR assessed by the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. The primary endpoint is the progression of DR during follow-up, which is defined as an increase of two or more steps in the ETDRS scale. The secondary endpoints include the concomitant changes in visual acuity, presence, number, location and type of retinal lesions, and retinal blood vessel diameter as well as the arteriovenous ratio at different visits.

ETHICS AND DISSEMINATION

Each local ethics committee (first Vote: Ethical Review Committees of Zhongda Hospital of Southeast University (2019ZDSYLL132-P01)) has approved the study. The results will be published in high impact peer-reviewed scientific journals aimed at the general reader.

TRIAL REGISTRATION NUMBERS

NCT04283162.

Diabetic Retinopathy and NADPH Oxidase-2: A Sweet Slippery Road

Diabetic retinopathy remains the leading cause of vision loss in working-age adults. The multi-factorial nature of the disease, along with the complex structure of the retina, have hindered in elucidating the exact molecular mechanism(s) of this blinding disease. Oxidative stress appears to play a significant role in its development and experimental models have shown that an increase in cytosolic Reacttive Oxygen Speies (ROS) due to the activation of NADPH oxidase 2 (Nox2), is an early event, which damages the mitochondria, accelerating loss of capillary cells. One of the integral proteins in the assembly of Nox2 holoenzyme, Rac1, is also activated in diabetes, and due to epigenetic modifications its gene transcripts are upregulated. Moreover, addition of hyperlipidemia in a hyperglycemic milieu (type 2 diabetes) further exacerbates Rac1-Nox2-ROS activation, and with time, this accelerates and worsens the mitochondrial damage, ultimately leading to the accelerated capillary cell loss and the development of diabetic retinopathy. Nox2, a multicomponent enzyme, is a good candidate to target for therapeutic interventions, and the inhibitors of Nox2 and Rac1 (and its regulators) are in experimental or clinical trials for other diseases; their possible use to prevent/halt retinopathy will be a welcoming sign for diabetic patients.

Artesunate alleviates diabetic retinopathy by activating autophagy via the regulation of AMPK/SIRT1 pathway

CONTEXT

Artesunate (ART), an antimalarial drug, possesses the ability to induce autophagy and exhibits a protective effect on diabetes.

OBJECTIVE

This study aimed to evaluate the effects of ART on diabetic retinopathy (DR) and to explore the underlying mechanisms.

METHODS

Rats with streptozotocin-induced DR were given intravitreal injection of ART.

RESULTS

ART administration inhibited the increase in retinal thickness and prevented blood-retinal barrier in diabetic rats. Further, vascular leukocyte adherence, microglial activation, inflammatory cytokine, and ROS production in the retinas of diabetic rats were also inhibited by ART. Additionally, ART enhanced autophagy in the retinas of diabetic rats as demonstrated by up-regulated Beclin-1 expression and LC3II/I ratio and down-regulated p62. ART also activated AMP-activated protein kinase (AMPK)/sensor class III histone deacetylase sirtuin 1 (SIRT1) pathway.

CONCLUSIONS

ART, as an autophagy activator, has therapeutic potential in DR treatment.

Overexpression of D-amino acid oxidase prevents retinal neurovascular pathologies in diabetic rats

AIMS/HYPOTHESIS

Diabetic retinopathy is characterised by retinal neurodegeneration and retinal vascular abnormalities, affecting one third of diabetic patients with disease duration of more than 10 years. Accumulated evidence suggests that serine racemase (SR) and D-serine are correlated with the pathogenesis of diabetic retinopathy and the deletion of the Srr gene reverses neurovascular pathologies in diabetic mice. Since D-serine content is balanced by SR synthesis and D-amino acid oxidase (DAAO) degradation, we examined the roles of DAAO in diabetic retinopathy and further explored relevant therapy.

METHODS

Rats were used as a model of diabetes by i.p. injection of streptozotocin at the age of 2 months and blood glucose was monitored with a glucometer. Quantitative real-time PCR was used to examine Dao mRNA and western blotting to examine targeted proteins in the retinas. Bisulphite sequencing was used to examine the methylation of Dao mRNA promoter in the retinas. Intravitreal injection of DAAO-expressing adenovirus (AAV8-DAAO) was conducted one week before streptozotocin administration. Brain specific homeobox/POU domain protein 3a (Brn3a) immunofluorescence was conducted to indicate retinal ganglion cells at 3 months after virus injection. The permeability of the blood-retinal barrier was examined by Evans blue leakage from retinal capillaries. Periodic acid-Schiff staining and haematoxylin counterstaining were used to indicate retinal vasculature, which was further examined with double immunostaining at 7 months after virus injection.

RESULTS

At the age of 12 months, DAAO mRNA and protein levels in retinas from diabetic animals were reduced to 66.2% and 70.4% of those from normal (control) animals, respectively. The Dao proximal promoter contained higher levels of methylation in diabetic than in normal retinas. Consistent with the observation, DNA methyltransferase 1 was increased in diabetic retinas. Injection of DAAO-expressing virus completely prevented the loss of retinal ganglion cells and the disruption of blood-retinal barrier in diabetic rats. Diabetic retinas contained retinal ganglion cells at a density of 54 ± 4/mm2, which was restored to 68 ± 9/mm2 by DAAO overexpression, similar to the levels in normal retinas. The ratio between the number of endothelial cells and pericytes in diabetic retinas was 6.06 ± 1.93/mm2, which was reduced to 3.42 ± 0.55/mm2 by DAAO overexpression; the number of acellular capillaries in diabetic retinas was 10 ± 5/mm2, which was restored to 6 ± 2/mm2 by DAAO overexpression, similar to the levels in normal retinas. Injection of the DAAO-expressing virus increased the expression of occludin and reduced gliosis, which were examined to probe the mechanism by which the disrupted blood-retinal barrier in diabetic rats was rescued and retinal neurodegeneration was prevented.

CONCLUSIONS/INTERPRETATION

Altogether, overexpression of DAAO before the onset of diabetes protects against neurovascular abnormalities in retinas from diabetic rats, which suggests a novel strategy for preventing diabetic retinopathy. Graphical abstract.

Sustained Inhibition of NF-κB Activity Mitigates Retinal Vasculopathy in Diabetes

This study investigated the effects of long-term NF-κB inhibition in mitigating retinal vasculopathy in a type 1 diabetic mouse model (Akita, Ins2^Akita). Akita and wild-type (C57BL/6J) male mice, 24 to 26 weeks old, were treated with or without a selective inhibitor of NF-κB, 4-methyl-N1-(3-phenyl-propyl) benzene-1,2-diamine (JSH-23), for 4 weeks. Treatment was given when the mice were at least 24 weeks old. Metabolic parameters, key inflammatory mediators, blood-retinal barrier junction molecules, retinal structure, and function were measured. JSH-23 significantly lowered basal glucose levels and intraocular pressure in Akita. It also mitigated vascular remodeling and microaneurysms significantly. Optical coherence tomography of untreated Akita showed thinning of retinal layers; however, treatment with JSH-23 could prevent it. Electroretinogram demonstrated that A- and B-waves in Akita were significantly smaller than in wild type mice, indicating that JSH-23 intervention prevented loss of retinal function. Protein levels and gene expression of key inflammatory mediators, such as NOD-like receptor family pyrin domain-containing 3, intercellular adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2, were decreased after JSH-23 treatment. At the same time, connexin-43 and occludin were maintained. Vision-guided behavior also improved significantly. The results show that reducing inflammation could protect the diabetic retina and its vasculature. Findings appear to have broader implications in treating not only ocular conditions but also other vasculopathies.

Luo Tong Formula Alleviates Diabetic Retinopathy in Rats Through Micro-200b Target

Aim: Diabetic retinopathy (DR) is a serious complication of diabetes (DM). Luo Tong formula (LTF) exerts protective effects against DR in rats, but its underlying mechanism remains unknown. Methods: Sprague-Dawley rats injected with streptozotocin (STZ) were used as an experimental diabetes model. LTF or calcium dobesilate (CaD) was administered to diabetic rats via gastric gavage. After the 12 weeks of treatment, blood and tissue samples were collected to determine serum glucose and retinal structure. Blood samples were collected for blood glucose and hemorheology analysis. Gene or protein expression levels were evaluated by immunohistochemistry, western blotting and/or quantitative real-time polymerase chain reaction (PCR). Results: DM rats exhibits significantly increased blood retinal-barrier (BRB) breakdown and VEGF/VEGFR expression in the retina, and decreased miR-200b and tight junction ZO-1/Occludin/ Claudin-5 genes expression, as well as Ang-1/Tie-2 expressions in the retina compared to normal control group. LTF treatment significantly moderated histological abnormalities in diabetic rats, independent of blood glucose level; improved some hemorrheological parameters; decreased the expressions of VEGF/VEGFR and BRB breakdown, significantly increased PEDF and tight junction proteins ZO-1/Occludin, as well as increased retinal miR-200b expression compared to non-treatment diabetic rats. Moreover, LTF prevented the reduction in Ang-1/Tie-2 expression. Conclusions: LTF treatment ameliorated DR through its repair vascular and attenuate vascular leakage. A mechanism involving miR-200b may contribute to benefit effects.

Update on the Effects of Antioxidants on Diabetic Retinopathy: In Vitro Experiments, Animal Studies and Clinical Trials

Current therapies for diabetic retinopathy (DR) incorporate blood glucose and blood pressure control, vitrectomy, photocoagulation, and intravitreal injections of anti-vascular endothelial growth factors or corticosteroids. Nonetheless, these techniques have not been demonstrated to completely stop the evolution of this disorder. The pathophysiology of DR is not fully known, but there is more and more evidence indicating that oxidative stress is an important mechanism in the progression of DR. In this sense, antioxidants have been suggested as a possible therapy to reduce the complications of DR. In this review we aim to assemble updated information in relation to in vitro experiments, animal studies and clinical trials dealing with the effect of the antioxidants on DR.

A New Human Blood-Retinal Barrier Model Based on Endothelial Cells, Pericytes, and Astrocytes

Blood-retinal barrier (BRB) dysfunction represents one of the most significant changes occurring during diabetic retinopathy. We set up a high-reproducible human-based in vitro BRB model using retinal pericytes, retinal astrocytes, and retinal endothelial cells in order to replicate the human in vivo environment with the same numerical ratio and layer order. Our findings showed that high glucose exposure elicited BRB breakdown, enhanced permeability, and reduced the levels of junction proteins such as ZO-1 and VE-cadherin. Furthermore, an increased expression of pro-inflammatory mediators (IL-1β, IL-6) and oxidative stress-related enzymes (iNOS, Nox2) along with an increased production of reactive oxygen species were observed in our triple co-culture paradigm. Finally, we found an activation of immune response-regulating signaling pathways (Nrf2 and HO-1). In conclusion, the present model mimics the closest human in vivo milieu, providing a valuable tool to study the impact of high glucose in the retina and to develop novel molecules with potential effect on diabetic retinopathy.

Keep an eye on adenosine: Its role in retinal inflammation

Adenosine is an endogenous purine nucleoside ubiquitously distributed throughout the body that interacts with G protein-coupled receptors, classified in four subtypes: A₁R, A_2AR, A_2BR and A₃R. Among the plethora of functions of adenosine, it has been increasingly recognized as a key mediator of the immune response. Neuroinflammation is a feature of chronic neurodegenerative diseases and contributes to the pathophysiology of several retinal degenerative diseases. Animal models of retinal diseases are helping to elucidate the regulatory roles of adenosine receptors in the development and progression of those diseases. Mounting evidence demonstrates that the adenosinergic system is altered in the retina during pathological conditions, compromising retinal physiology. This review focuses on the roles played by adenosine and the elements of the adenosinergic system (receptors, enzymes, transporters) in the neuroinflammatory processes occurring in the retina. An improved understanding of the molecular and cellular mechanisms of the signalling pathways mediated by adenosine underlying the onset and progression of retinal diseases will pave the way towards the identification of new therapeutic approaches.

Protective effects of pharmacological agents against aminoglycoside-induced nephrotoxicity: A systematic review

Introduction: Aminoglycosides have been long used for antibacterial treatment and are still commonly used in clinical practice. Despite their extensive application and positive effects, drug-related toxicity is considered as the main obstacle for aminoglycosides. Aminoglycosides induce nephrotoxicity through the endocytosis and accumulation of the antibiotics in the epithelial cells of proximal tubule. Most importantly, however, a number of pharmacological agents were demonstrated to have protective activities against nephrotoxicity in experimental animals.Areas covered: In the present systematic review, the authors provide and discuss the mechanisms and epidemiological features of aminoglycoside-induced nephrotoxicity, and focus mainly on recent discoveries and key features of pharmacological interventions. In total, 39 articles were included in this review.Expert opinion: The majority of studies investigated gentamicin-induced nephrotoxicity in animal models. Antioxidants, chemicals, synthetic drugs, hormones, vitamins, and minerals showed potential values to prevent gentamicin-induced nephrotoxicity. Indicators used to evaluate the effectiveness of nephroprotection included antioxidative indexes, inflammatory responses, and apoptotic markers. Among the nephroprotective agents studied, herbs and natural antioxidant agents showed excellent potential to provide a protective strategy against gentamicin-induced nephrotoxicity.

Calcium dobesilate reduces VEGF signaling by interfering with heparan sulfate binding site and protects from vascular complications in diabetic mice

Inhibiting vascular endothelial growth factor (VEGF) is a therapeutic option in diabetic microangiopathy. However, VEGF is needed at physiological concentrations to maintain glomerular integrity; complete VEGF blockade has deleterious effects on glomerular structure and function. Anti-VEGF therapy in diabetes raises the challenge of reducing VEGF-induced pathology without accelerating endothelial cell injury. Heparan sulfate (HS) act as a co-receptor for VEGF. Calcium dobesilate (CaD) is a small molecule with vasoprotective properties that has been used for the treatment of diabetic microangiopathy. Preliminary evidence suggests that CaD interferes with HS binding sites of fibroblast growth factor. We therefore tested the hypotheses that (1) CaD inhibits VEGF signaling in endothelial cells, (2) that this effect is mediated via interference between CaD and HS, and (3) that CaD ameliorates diabetic nephropathy in a streptozotocin-induced diabetic mouse model by VEGF inhibition. We found that CaD significantly inhibited VEGF₁₆₅-induced endothelial cell migration, proliferation, and permeability. CaD significantly inhibited VEGF₁₆₅-induced phosphorylation of VEGFR-2 and suppressed the activity of VEGFR-2 mediated signaling cascades. The effects of CaD in vitro were abrogated by heparin, suggesting the involvement of heparin-like domain in the interaction with CaD. In addition, VEGF₁₂₁, an isoform which does not bind to heparin, was not inhibited by CaD. Using the proximity ligation approach, we detected inhibition of interaction in situ between HS and VEGF and between VEGF and VEGFR-2. Moreover, CaD reduced VEGF signaling in mice diabetic kidneys and ameliorated diabetic nephropathy and neuropathy, suggesting CaD as a VEGF inhibitor without the negative effects of complete VEGF blockade and therefore could be useful as a strategy in treating diabetic nephropathy.

Luo Tong formula attenuates retinal inflammation in diabetic rats via inhibition of the p38MAPK/NF-κB pathway

Background

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes and remains the leading cause of blindness in adults. Retinal inflammation is playing a crucial role in the development of DR, and targeting inflammatory mediators is a promising strategy for controlling DR. Here, we investigated compound Chinese medicine Luo Tong formula (LTF) alleviated retinal inflammatory responses in a STZ-induced diabetic rat model.

Methods

Sprague–Dawley rats were divided into four groups: control, streptozotocin-induced diabetic, LTF-treated diabetic, and calcium dobesilate (CaD)-treated diabetic rats. Blood samples were collected for blood glucose examination. Hematoxylin–eosin and periodic acid-Schiff staining were conducted for light microscopy observations. Retinal cell apoptosis was detected using the TUNEL assay. Proteins expression was quantified by Western blotting and/or immunohistochemistry, and gene expression was assessed by real-time PCR.

Results

Diabetic rats showed significant increases in the expression of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), nuclear factor-κB (NF-κB), and the phospho-p38 mitogen-activated protein kinase (p-p38-MAPK)/p38 MAPK ratio compared to control rats. LTF treatment significantly improved both retinal and pancreatic pathological injury, LTF treatment also inhibited inducible the p-p38 MAPK/p38 MAPK ratio and NF-κB activation and decreased the subsequent induction of the retinal expression of proinflammatory mediators TNF-α, IL-1β, MCP-1 and ICAM-1 compared to diabetic rats. LTF also exhibited a protective effect on islet function.

Conclusions

LTF before the onset of DR can alleviate retinal pathological injury, LTF may play an anti-inflammatory role by inhibiting p38-MAPK and then inhibiting NF-κB pathway. But further studies are needed to confirm this conclusion.

Trial registration This is an animal experiment, trial registration is not necessary.

Investigation of the Mechanism Underlying Calcium Dobesilate-Mediated Improvement of Endothelial Dysfunction and Inflammation Caused by High Glucose

Background/Aims

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease. Calcium dobesilate (CaD) is widely used to treat diabetic retinopathy. Recent studies have demonstrated that CaD exerts protective effects against diabetic nephropathy. The aim of this study was to elucidate the molecular and cellular mechanisms underlying the protective effects of CaD.

Methods

Human umbilical vein endothelial cells (HUVECs) were cultured with different D-glucose concentrations to determine the effects of high glucose on HUVEC gene expression. HUVECs were also incubated with CaD (25 μM, 50 μM, and 100 μM) for 3 days to determine the effects of CaD on HUVEC viability. db/db mice were treated with CaD. 2-[(Aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1) blocked the nuclear factor-κB (NF-κB) pathway in HUVECs. A pentraxin 3 (PTX3) small interfering RNA (siRNA) intervention experiment was performed in the cells. An adenovirus-encapsulated PTX3 siRNA intervention experiment was performed in db/db mice. Western blot and real-time PCR analyses were used to detect PTX3, p-IKBa/IKBa (I-kappa-B-alpha), and p-eNOS/eNOS (endothelial nitric oxide synthase) expression in mice and HUVECs. Hematoxylin-eosin (HE) staining and periodic acid-Schiff (PAS) staining were used to observe renal tissue damage in mice. PTX3 expression was observed by immunohistochemical staining.

Results

CaD downregulated the expression of PTX3 and p-IKBa/IKBa and upregulated the expression of p-eNOS/eNOS in vitro. When TPCA-1 was used, high glucose induced high PTX3 expression, and the expression of p-eNOS/eNOS increased. After PTX3 gene silencing, the expression of p-eNOS/eNOS also increased. In vivo, CaD reduced the expression of PTX3 and p-IKBa/IKBa in the kidneys of db/db mice and increased the expression of p-eNOS/eNOS. After PTX3 gene silencing, the urine protein and renal function of db/db mice were ameliorated, the glomerular extracellular matrix was decreased, and the expression of p-eNOS/eNOS was increased.

Conclusions

Our results suggested that CaD may inhibit the expression of PTX3 by altering the IKK/IKB/NF-κB pathway, thereby improving endothelial dysfunction in HUVECs. PTX3 may be a potential therapeutic target for DKD.

Endothelial tight junctions and their regulatory signaling pathways in vascular homeostasis and disease

Endothelial tight junctions (TJs) regulate the transport of water, ions, and molecules through the paracellular pathway, serving as an important barrier in blood vessels and maintaining vascular homeostasis. In endothelial cells (ECs), TJs are highly dynamic structures that respond to multiple external stimuli and pathological conditions. Alterations in the expression, distribution, and structure of endothelial TJs may lead to many related vascular diseases and pathologies. In this review, we provide an overview of the assessment methods used to evaluate endothelial TJ barrier function both in vitro and in vivo and describe the composition of endothelial TJs in diverse vascular systems and ECs. More importantly, the direct phosphorylation and dephosphorylation of TJ proteins by intracellular kinases and phosphatases, as well as the signaling pathways involved in the regulation of TJs, including and the protein kinase C (PKC), PKA, PKG, Ras homolog gene family member A (RhoA), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and Wnt/β-catenin pathways, are discussed. With great advances in this area, targeting endothelial TJs may provide novel treatment for TJ-related vascular pathologies.

Relationships Between Neurodegeneration and Vascular Damage in Diabetic Retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes and constitutes a major cause of vision impairment and blindness in the world. DR has long been described exclusively as a microvascular disease of the eye. However, in recent years, a growing interest has been focused on the contribution of neuroretinal degeneration to the pathogenesis of the disease, and there are observations suggesting that neuronal death in the early phases of DR may favor the development of microvascular abnormalities, followed by the full manifestation of the disease. However, the mediators that are involved in the crosslink between neurodegeneration and vascular changes have not yet been identified. According to our hypothesis, vascular endothelial growth factor (VEGF) could probably be the most important connecting link between the death of retinal neurons and the occurrence of microvascular lesions. Indeed, VEGF is known to play important neuroprotective actions; therefore, in the early phases of DR, it may be released in response to neuronal suffering, and it would act as a double-edged weapon inducing both neuroprotective and vasoactive effects. If this hypothesis is correct, then any retinal stress causing neuronal damage should be accompanied by VEGF upregulation and by vascular changes. Similarly, any compound with neuroprotective properties should also induce VEGF downregulation and amelioration of the vascular lesions. In this review, we searched for a correlation between neurodegeneration and vasculopathy in animal models of retinal diseases, examining the effects of different neuroprotective substances, ranging from nutraceuticals to antioxidants to neuropeptides and others and showing that reducing neuronal suffering also prevents overexpression of VEGF and vascular complications. Taken together, the reviewed evidence highlights the crucial role played by mediators such as VEGF in the relationship between retinal neuronal damage and vascular alterations and suggests that the use of neuroprotective substances could be an efficient strategy to prevent the onset or to retard the development of DR.

Calcium Dobesilate Restores Autophagy by Inhibiting the VEGF/PI3K/AKT/mTOR Signaling Pathway

Objective: Calcium dobesilate (CaD), an effective drug for the treatment of diabetic microvascular complications, especially diabetic retinopathy, is widely used in the clinic. Interestingly, several studies have indicated that CaD is therapeutic for diabetic kidney disease (DKD). Recently, evidence has indicated that altered vascular endothelial growth factor (VEGF) expression and decreased autophagy are the main pathological mechanisms of proteinuria. Thus, this study was conducted to explore the effect of CaD on restoring autophagy in DKD and the possible signaling pathway between VEGF and autophagy. Methods: Obese mice with spontaneous diabetes (KK-Ay) and high-fat diet- and streptozotocin-induced diabetic mice (HFD/STZ) were used in this study. Biochemical staining, western blotting, and immunohistochemistry were conducted to determine the angioprotective effect of CaD and the underlying mechanism between autophagy and VEGF/VEGFR. Results: Our results showed that CaD was capable of reducing albuminuria and restoring renal histological changes in KK-Ay and HFD/STZ-induced diabetic mice. CaD restored autophagy by decreasing the protein expression of LC3 II, Atg5, and beclin 1 and increasing the expression of P62. Moreover, CaD reduced the activation of the autophagy-related PI3K/AKT/mTOR pathway possibly via decreasing VEGF and downregulating VEGF receptor 2. Conclusion: Overall, CaD, as a novel potential therapeutic drug for DKD, plays a key role in protecting renal function and restoring autophagy by blocking VEGF/VEGFR2 and inhibiting the PI3K/AKT/mTOR signaling pathway.

The Regulatory Role of Rac1, a Small Molecular Weight GTPase, in the Development of Diabetic Retinopathy

Diabetic retinopathy, a microvascular complication of diabetes, remains the leading cause of vision loss in working age adults. Hyperglycemia is considered as the main instigator for its development, around which other molecular pathways orchestrate. Of these multiple pathways, oxidative stress induces many metabolic, functional and structural changes in the retinal cells, leading to the development of pathological features characteristic of this blinding disease. An increase in cytosolic reactive oxygen species (ROS), produced by cytosolic NADPH oxidase 2 (Nox2), is an early event in the pathogenesis of diabetic retinopathy, which leads to mitochondrial damage and retinal capillary cell apoptosis. Activation of Nox2 is mediated through an obligatory small molecular weight GTPase, Ras-related C3 botulinum toxin substrate 1 (Rac1), and subcellular localization of Rac1 and its activation are regulated by several regulators, rendering it a complex biological process. In diabetes, Rac1 is functionally activated in the retina and its vasculature, and, via Nox2-ROS, contributes to mitochondrial damage and the development of retinopathy. In addition, Rac1 is also transcriptionally activated, and epigenetic modifications play a major role in this transcriptional activation. This review focusses on the role of Rac1 and its regulation in the development and progression of diabetic retinopathy, and discusses some possible avenues for therapeutic interventions.

Gentiopicroside attenuates diabetic retinopathy by inhibiting inflammation, oxidative stress, and NF-κB activation in rat model

Diabetic retinopathy, an inflammatory condition, is one of the devastating complication associated with diabetes that can lead to irreversible blindness. Gentiopicroside (GP), a secoiridoid glycoside, exhibits anti-inflammatory and antioxidant activity. The investigation was carried out to explore whether GP could attenuate diabetic retinopathy in diabetic rats. Diabetes was induced by injecting streptozotocin (STZ) (65 mg/kg) intraperitoneally in 8-weeks-old male rats (200–240 g). The treatment group received GP (20, 40, 80 mg/kg) orally for a duration of 10 weeks in diabetic rats (n = 10), and the diabetic group animals received phosphate buffer solution (n = 20). Effect of GP on cell viability study was performed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Oxidative stress markers, inflammatory mediators, and angiogenic factors were quantified in the retinal tissues of diabetic animals. All data were analyzed by one-way analysis of variance (ANOVA) at P < 0.05. Cytoprotective effect of GP was observed in MTT assay. GP effectively downregulated inflammatory cytokine, nuclear factor κB (NF-κB), tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), and intercellular adhesion molecules-1 (ICAM-1), and upregulated antioxidant markers glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in the retina of diabetic rats. GP equilibrated the disturbed angiogenic factors in the diabetic retinal tissues. Results clearly indicated defensive role of GP in the treatment of diabetic retinopathy by inhibition of NF-κB and oxidative stress.

Calcium Dobesilate and Micro-vascular diseases

Micro-vascular diseases and its associated complications continue to be a significant health problem worldwide. Vascular lesions from microvascular involvement lead to impaired blood flow and contribute to damage and dysfunction of one or more target organs, that is, the heart, kidneys, eyes, and nervous system. Calcium Dobesilate Drug (CAD) is an established vasoactive and angioprotective drug that has shown a unique, multitarget mode of action in several experimental studies and in different animal models of diabetic microvascular complications. CAD has been widely used as an antioxidant and a vascular protective agent. At present, the application of Calcium Dobesilate is mainly related to Micro-vascular damage-related diseases, such as diabetic retinopathy (DR) and diabetic nephropathy (DN), and it is found to significantly improve the related symptoms. Its beneficial effects make it an attractive therapeutic compound especially in the early stages of these diseases. Scholars at home and abroad have studied the effectiveness, safety, and mechanisms of the related diseases, furthermore, the subjects involved patients and animal models, they have found some new clinical effects of this medicine. This paper makes a brief summary of a research progress of clinical application about Vascular injury related diseases and other aspects.

Therapeutic regulation of VE-cadherin with a novel oligonucleotide drug for diabetic eye complications using retinopathy mouse models

AIMS/HYPOTHESIS

A major feature of diabetic retinopathy is breakdown of the blood-retinal barrier, resulting in macular oedema. We have developed a novel oligonucleotide-based drug, CD5-2, that specifically increases expression of the key junctional protein involved in barrier integrity in endothelial cells, vascular-endothelial-specific cadherin (VE-cadherin). CD5-2 prevents the mRNA silencing by the pro-angiogenic microRNA, miR-27a. CD5-2 was evaluated in animal models of ocular neovascularisation and vascular leak to determine its potential efficacy for diabetic retinopathy.

METHODS

CD5-2 was tested in three mouse models of retinal dysfunction: conditional Müller cell depletion, streptozotocin-induced diabetes and oxygen-induced retinopathy. Vascular permeability in the Müller cell-knockout model was assessed by fluorescein angiography. The Evans Blue leakage method was used to determine vascular permeability in streptozotocin- and oxygen-induced retinopathy models. The effects of CD5-2 on retinal neovascularisation, inter-endothelial junctions and pericyte coverage in streptozotocin- and oxygen-induced retinopathy models were determined by staining for isolectin-B4, VE-cadherin and neural/glial antigen 2 (NG2). Blockmir CD5-2 localisation in diseased retina was determined using fluorescent in situ hybridisation. The effects of CD5-2 on VE-cadherin expression and in diabetic retinopathy-associated pathways, such as the transforming growth factor beta (TGF-β) and wingless/integrated (WNT) pathway, were confirmed using western blot of lysates from HUVECs, a mouse brain endothelial cell line and a VE-cadherin null mouse endothelial cell line.

RESULTS

CD5-2 penetrated the vasculature of the eye in the oxygen-induced retinopathy model. Treatment of diseased mice with CD5-2 resulted in reduced vascular leak in all three animal models, enhanced expression of VE-cadherin in the microvessels of the eye and improved pericyte coverage of the retinal vasculature in streptozotocin-induced diabetic models and oxygen-induced retinopathy models. Further, CD5-2 reduced the activation of retinal microglial cells in the streptozotocin-induced diabetic model. The positive effects of CD5-2 seen in vivo were further confirmed in vitro by increased protein expression of VE-cadherin, SMAD2/3 activity, and platelet-derived growth factor B (PDGF-B).

CONCLUSIONS/INTERPRETATION

CD5-2 has therapeutic potential for individuals with vascular-leak-associated retinal diseases based on its ease of delivery and its ability to reverse vascular dysfunction and inflammatory aspects in three animal models of retinopathy.

Ethanol Extract of Chinese Propolis Attenuates Early Diabetic Retinopathy by Protecting the Blood-Retinal Barrier in Streptozotocin-Induced Diabetic Rats

Propolis has been shown to reduce the level of blood glucose and suppress the histopathological changes in diabetics. However, it still remains unknown if propolis has a similar effect on diabetic retinopathy (DR). Our study aimed to evaluate the effect of the ethanol extract of Chinese propolis (EECP) on early DR in streptozotocin (STZ)-induced diabetic rats. EECP was given to diabetic rats by oral intubation for 12 weeks. The concentrations of fasting blood glucose (FBG), glycated hemoglobin (HbA1c), malondialdehyde (MDA), reactive oxygen species (ROS), and reactive nitrogen species (RNS) were measured. Pathological examinations, including hematoxylin and eosin (HE) staining, transmission electron microscopy (TEM), and immunofluorescence, were also conducted to provide further evidence of EECP's effect on early DR. EECP was able to attenuate diabetes via directly decreasing the levels of FBG and HbA1c, which also resulted in the reduction of MDA, ROS, and RNS. Furthermore, EECP could protect against the damages of photoreceptor cells, as well as retinal thickening. And the inhibition of blood-retinal barrier (BRB) leakage was also observed in EECP-treated diabetic rats, along with the inhibition the loss of tight junction proteins (occludin, ZO-1). These results suggest that EECP has an ameliorating effect on early DR by inhibition of blood-retinal barrier breakdown. PRACTICAL APPLICATION: This study sheds light on the protective effect of the ethanol extract of Chinese propolis on early diabetic retinopathy and the molecular actions underlying the inhibition of blood-retinal barrier breakdown. Our study suggests that ethanol extract of Chinese propolis can be considered as a potential therapeutic agent in the treatment of early diabetic retinopathy.

Sweet Stress: Coping With Vascular Dysfunction in Diabetic Retinopathy

Oxidative stress plays key roles in the pathogenesis of retinal diseases, such as diabetic retinopathy. Reactive oxygen species (ROS) are increased in the retina in diabetes and the antioxidant defense system is also compromised. Increased ROS stimulate the release of pro-inflammatory cytokines, promoting a chronic low-grade inflammation involving various signaling pathways. An excessive production of ROS can lead to retinal endothelial cell injury, increased microvascular permeability, and recruitment of inflammatory cells at the site of inflammation. Recent studies have started unraveling the complex crosstalk between retinal endothelial cells and neuroglial cells or leukocytes, via both cell-to-cell contact and secretion of cytokines. This crosstalk is essential for the maintenance of the integrity of retinal vascular structure. Under diabetic conditions, an aberrant interaction between endothelial cells and other resident cells of the retina or invading inflammatory cells takes place in the retina. Impairment in the secretion and flow of molecular signals between different cells can compromise the retinal vascular architecture and trigger angiogenesis. In this review, the synergistic contributions of redox-inflammatory processes for endothelial dysfunction in diabetic retinopathy will be examined, with particular attention paid to endothelial cell communication with other retinal cells.

Subtle thinning of retinal layers without overt vascular and inflammatory alterations in a rat model of prediabetes

PURPOSE

Diabetic retinopathy is a neurovascular disease characterized by increased permeability of the blood-retinal barrier, changes in the neural components of the retina, and low-grade chronic inflammation. Diabetic retinopathy is a major complication of diabetes; however, the impact of a prediabetic state on the retina remains to be elucidated. The aim of this study was to assess possible early retinal changes in prediabetic rats, by evaluating changes in the integrity of the blood-retinal barrier, the retinal structure, neural markers, and inflammatory mediators.

METHODS

Several parameters were analyzed in the retinas of Wistar rats that drank high sucrose (HSu; 35% sucrose solution during 9 weeks, the prediabetic animal model) and were compared with those of age-matched controls. The permeability of the blood-retinal barrier was assessed with the Evans blue assay, and the content of the tight junction proteins and neural markers with western blotting. Optical coherence tomography was used to evaluate retinal thickness. Cell loss at the ganglion cell layer was assessed with terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay and by evaluating the immunoreactivity of the Brn3a transcription factor. To assess retinal neuroinflammation, the mRNA expression and protein levels of inducible nitric oxide synthase isoform (iNOS), interleukin-1 beta (IL-1β), and tumor necrosis factor (TNF) were evaluated. Iba1 and MHC-II immunoreactivity and translocator protein (TSPO) mRNA levels were assessed to study the microglial number and activation state.

RESULTS

The thickness of the inner retinal layers of the HSu-treated animals decreased. Nevertheless, no apoptotic cells were observed, and no changes in retinal neural markers were detected in the retinas of the HSu-treated animals. No changes were detected in the permeability of the blood-retinal barrier, as well as the tight junction protein content between the HSu-treated rats and the controls. In addition, the inflammatory parameters remained unchanged in the retina despite the tendency for an increase in the number of retinal microglial cells.

CONCLUSIONS

In a prediabetic rat model, the retinal structure is affected by the thinning of the inner layers, without overt vascular and inflammatory alterations. The results suggest neuronal dysfunction (thinning of the inner retina) that may precede or anticipate the vascular and inflammatory changes. Subtle structural changes might be viewed as early disturbances in an evolving disease, suggesting that preventive strategies (such as the modification of diet habits) could be applied at this stage, before the progression toward irreversible dysfunction and damage to the retina.

Blood-Brain Barrier Disruption Induced Cognitive Impairment Is Associated With Increase of Inflammatory Cytokine

Patients with diabetes suffer the higher risk of dementia and the underlying pathological mechanism of cognitive dysfunction in diabetes is not fully understood. In this study, we explore whether the cognitive impairment in the diabetic rat is associated with increased blood brain barrier (BBB) permeability and the change of the inflammatory cytokine. Experimental diabetic rats were induced by single intraperitoneal injection of streptozotocin (STZ). Cognitive function was evaluated by Morris water maze in the normal and the diabetic rats, respectively. The spatial acquisition trials were conducted over five consecutive days and the probe test was performed on day 6, followed by working memory test on the next 4 days. Escape latency was recorded in the acquisition trials and working memory test; time spent in the target quadrant and the number of crossing the former platform were recorded in the probe test. BBB permeability was assessed by measuring the extravasation of IgG. The image of occludin and claudin-5 staining by a confocal microscope were acquired to measure the gap in the tight junction. Cytokines TNF-α, IL-1β and IL-6 mRNA expression were further examined by Real-time PCR. The time spent in the target quadrant within 30 s decreased in the 8-week STZ rats compared to that of the normal rats (p < 0.05), while no difference was seen in the performance of working memory between the diabetic and normal rats. IgG leakage significantly increased in the brain parenchyma of the 8-week STZ rats compared to the normal rats (p < 0.05). The immunostaining of occludin and claudin-5 suggested the gap in the tight junction increased in the 8-week STZ rats compared to the normal rats (p < 0.05). Moreover, TNF-α and IL-6 mRNA also increased in the brain of 8-week STZ rats compared to the normal rats (p < 0.05). These results suggested that loss of BBB integrity might contribute to progressive impairment of cognitive in the diabetic rats. The increase of TNF-α and IL-6 expression might trigger the disruption of BBB in the brain, which eventually caused cognitive impairment in the 8-week STZ rats.

Haemostatic agent etamsylate in vitro and in vivo antagonizes anti-coagulant activity of heparin

Etamsylate is indicated for several anti-hemorrhagic indications in human and veterinary medicine. However, etamsylate has been shown to be effective only in specific hemorrhagic situations. Furthermore, mechanism of action of etamsylate is not known but recent research has shown its ability to inhibit heparin binding to several growth factors. We have evaluated the ability of etamsylate to interfere with the activities of heparin. Effects of etamsylate on vasodilatory activity of heparin were evaluated in rat aortic segments. Influence of etamsylate on anticoagulant activity of heparin was evaluated in vitro by determining prothrombin (PT) time and activated partial thromboplastin time (aPTT) in dog blood and in vivo by determining the interference of systemic and topical etamsylate on heparin-induced extension in bleeding time (BT) in rats. Despite failing to inhibit heparin-induced vasodilation of rat aorta, etamsylate significantly reduced the increase in aPTT caused by heparin (+30.4 ± 6.7% vs. +15.0 ± 2.8% for etamsylate at 100 µM, P < 0.05). Etamsylate also antagonized the anticoagulant effects driven by heparin in vivo since prevented the heparin-induced increase in BT when systemically (i.p.) administered (+94.6 ± 7.5% vs. +57.9 ± 9.2% at 10 mg/kg, P < 0.05, vs. +22.2 ± 16.8% at 30 mg/kg, P < 0.01). Additionally, topically applied etamsylate (125 mg/ml) significantly reduced heparin-induced BT increase (+102.5 ± 3.2% vs. +54.0 ± 5.8%, P < 0.01). These evidences show a pharmacological interference by etamsylate on heparin activities antagonizing pro-hemorrhagic effects of heparin in vitro and in vivo without inhibiting its vasodilatory properties. This ability could help to explain pharmacological effects of etamsylate and proposes its role for reversing pro-hemorrhagic states.

The potential benefits of glucagon-like peptide-1 receptor agonists for diabetic retinopathy

For a long time, diabetic retinopathy (DR) has been one of the most severe complications of diabetes. The early treatment of DR is not clearly recognized. The additional benefit of hypoglycemic agents for DR has become a new research field. Glucagon-like peptide-1 receptor (GLP-1R) has been shown to be widely expressed in tissues including retina. Glucagon-like peptide-1 receptor agonists (GLP-1RA) have been generally used in the treatment of diabetic patients. Studies shows that GLP-1RA could inhibit nerve damage by decrease apoptosis of nerve cells and activation of glial cells. In addition, GLP-1RA plays a protective role for tight junction (TJ) and cells of blood retinal barrier (BRB). It also protects retina from BRB damage. In this review, we discuss the potential protective mechanisms of GLP-1RA for DR beyond the hypoglycemic effects.

Vitamin D3 Protects against Diabetic Retinopathy by Inhibiting High-Glucose-Induced Activation of the ROS/TXNIP/NLRP3 Inflammasome Pathway

PURPOSE

This study aimed to evaluate the mechanisms underlying the effects of 1,25-dihydroxyvitamin D (vitamin D₃) on diabetes-induced retinal vascular damage and retinal vascular endothelial cell apoptosis.

METHODS

Diabetic and control rats were randomly assigned to receive vitamin D₃ or vehicle for 6 months. Additionally, human retinal microvascular endothelial cells (HRMECs) were incubated in normal or high-glucose medium with or without vitamin D₃. Morphological changes in retinal tissues and retinal vascular permeability were examined, and cellular apoptosis was detected by fluorescence staining. Intracellular reactive oxygen species (ROS) levels were determined using fluorescent probes. Proteins were examined by Western blotting.

RESULTS

Vitamin D₃ significantly downregulated intracellular ROS and inhibited TRX-interacting protein (TXNIP)/NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathway activation. Additionally, vitamin D₃ reduced vascular endothelial growth factor (VEGF) expression and the Bax/Bcl-2 ratio. These changes were associated with retinal recovery and with decreases in retinal vascular permeability and retinal capillary cell apoptosis.

CONCLUSIONS

Vitamin D₃ decreases diabetes-induced ROS and exerts protective effects against retinal vascular damage and cell apoptosis in association with inhibition of the ROS/TXNIP/NLRP3 inflammasome pathway. Understanding the mechanisms of action of vitamin D₃ has important implications for preventing and treating inflammatory-related illnesses such as diabetic retinopathy.

Molecular Mechanisms and Treatment Strategies in Diabetic Nephropathy: New Avenues for Calcium Dobesilate-Free Radical Scavenger and Growth Factor Inhibition

Diabetic nephropathy is one of the most important microvascular complications of diabetes mellitus and is responsible for 40–50% of all cases of end stage renal disease. The therapeutic strategies in diabetic nephropathy need to be targeted towards the pathophysiology of the disease. The earlier these therapeutic strategies can bring about positive effects on vascular changes and prevent the vasculature in patients with diabetes from deteriorating, the better the renal function can be preserved. Studies evaluating anti-inflammatory and antioxidative strategies in diabetic nephropathy demonstrate the need and value of these novel treatment avenues. CaD is an established vasoactive and angioprotective drug that has shown a unique, multitarget mode of action in several experimental studies and in different animal models of diabetic microvascular complications. On the molecular level, CaD reduces oxidative stress and inhibits growth factors such as fibroblast growth factor and vascular endothelial growth factors. Recent findings have demonstrated a strong rationale for its use in reducing urine albumin excretion rate and markers of inflammation as well as improving endothelial function. Its beneficial effects make it an attractive therapeutic compound especially in the early stages of the disease. These findings, although promising, need further confirmation in prospective clinical trials with CaD.

Endothelial progenitor cells transplantation attenuated blood-brain barrier damage after ischemia in diabetic mice via HIF-1α

Background

Blood-brain barrier impairment is a major indicator of endothelial dysfunction in diabetes. Studies showed that endothelial progenitor cell (EPC) transplantation promoted angiogenesis and improved function recovery after hind limb ischemia in diabetic mice. The effect of EPC transplantation on blood-brain barrier integrity after cerebral ischemia in diabetic animals is unknown. The aim of this study is to explore the effect of EPC transplantation on the integrity of the blood-brain barrier after cerebral ischemia in diabetic mice.

Methods

EPCs were isolated by density gradient centrifugation and characterized by flow cytometry and immunostaining. Diabetes was induced in adult male C57BL/6 mice by a single injection of streptozotocin at 4 weeks before surgery. Diabetic mice underwent 90-minute transient middle cerebral artery occlusion surgery and received 1 × 10⁶ EPCs transplantation immediately after reperfusion. Brain infarct volume, blood-brain barrier permeability, tight junction protein expression, and hypoxia inducible factor-1α (HIF-1α) mRNA level were examined after treatment.

Results

We demonstrated that neurological deficits were attenuated and brain infarct volume was reduced in EPC-transplanted diabetic mice after transient cerebral ischemia compared to the controls (p < 0.05). Blood-brain barrier leakage and tight junction protein degradation were reduced in EPC-transplanted mice (p <0.05). EPCs upregulated HIF-1α expression while HIF-1α inhibitor PX-478 abolished the beneficial effect of EPCs.

Conclusions

We conclude that EPCs protected blood-brain barrier integrity after focal ischemia in diabetic mice through upregulation of HIF-1α signaling.

Scutellaria barbata attenuates diabetic retinopathy by preventing retinal inflammation and the decreased expression of tight junction protein

AIM

To observe the attenuation of ethanol extract of Herba Scutellaria barbata (SE) against diabetic retinopathy (DR) and its engaged mechanism.

METHODS

C57BL/6J mice were intraperitoneally injected with streptozotocin (STZ, 55 mg/kg) for 5 consecutive days to induce diabetes. The diabetic mice were orally given with SE (100, 200 mg/kg) for 1mo at 1mo after STZ injection. Blood-retinal barrier (BRB) breakdown was detected by using Evans blue permeation assay. Real-time polymerase chain reaction (RT-PCR), Western blot and immunofluorescence staining were used to detect mRNA and protein expression. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum contents of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β.

RESULTS

SE (100, 200 mg/kg) reversed the breakdown of BRB in STZ-induced diabetic mice. The decreased expression of retinal claudin-1 and claudin-19, which are both tight junction (TJ) proteins, was reversed by SE. SE decreased the increased serum contents and retinal mRNA expression of TNF-α and IL-1β. SE also decreased the increased retinal expression of intercellular cell adhesion molecule-1 (ICAM-1). SE reduced the increased phosphorylation of nuclear factor kappa B (NFκB) p65 and its subsequent nuclear translocation in retinas from STZ-induced diabetic mice. Results of Western blot and retinal immunofluorescence staining of ionized calcium-binding adapter molecule 1 (Iba1) demonstrated that SE abrogated the activation of microglia cells in STZ-induced diabetic mice.

CONCLUSION

SE attenuates the development of DR by inhibiting retinal inflammation and restoring the decreased expression of TJ proteins including claudin-1 and claudin-19.