Association of Chemerin and Vascular Endothelial Growth Factor (VEGF) with Diabetic Nephropathy

Deletion of adipocyte NOS3 potentiates high-fat diet-induced hypertension and vascular remodelling via chemerin

AIMS

Obesity is an epidemic that is a critical contributor to hypertension and other cardiovascular diseases. Current paradigms suggest that endothelial nitric oxide synthase (eNOS/NOS3) in the vessel wall is the primary regulator of vascular function and blood pressure. However, recent studies have revealed the presence of eNOS/NOS3 in the adipocytes of white adipose tissues and perivascular adipose tissues (PVATs). The current understanding of the role of adipocyte NOS3 is based mainly on studies using global knockout models. The present study aimed to elucidate the functional significance of adipocyte NOS3 for vascular function and blood pressure control.

METHODS AND RESULTS

We generated an adipocyte-specific NOS3 knockout mouse line using adiponectin promoter-specific Cre-induced gene inactivation. Control and adipocyte-specific NOS3 knockout (A-NOS3 KO) mice were fed a high-fat diet (HFD). Despite less weight gain, A-NOS3 KO mice exhibited a significant increase in blood pressure after HFD feeding, associated with exacerbated vascular dysfunction and remodelling. A-NOS3 KO mice also showed increased expression of signature markers of inflammation and hypoxia in the PVATs. Among the differentially expressed adipokines, we have observed an upregulation of a novel adipokine, chemerin, in A-NOS3 KO mice. Chemerin was recently reported to link obesity and vascular dysfunction. Treatment with chemerin neutralizing antibody normalized the expression of remodelling markers in the aorta segments cultured in serum from HFD-fed A-NOS3 KO mice ex vivo.

CONCLUSION

These data suggest that NOS3 in adipocytes is vital in maintaining vascular homeostasis; dysfunction of adipocyte NOS3 contributes to obesity-induced vascular remodelling and hypertension.

CMKLR1 Antagonist Alpha-NETA Protects against Diabetic Nephropathy in Mice

INTRODUCTION

Diabetic nephropathy (DN) is a common complication in diabetic patients. Chemerin, a novel adipokine, has been associated with renal damage in DN. The chemerin chemokine-like receptor 1 (CMKLR1) has been reported to participate in DN. In this study, we aimed to investigate the effect of a CMKLR1 antagonist, 2-(anaphthoyl)ethyltrimethylammonium iodide (α-NETA), on DN.

METHODS

To induce diabetes, 8-week-old male C57BL/6J mice were given a single intraperitoneal injection of 65 mg/kg streptozotocin (STZ). Diabetic mice were randomly assigned to receive daily doses of 0, 5, or 10 mg/kg α-NETA for 4 weeks.

RESULTS

α-NETA dose-dependently induced body weight and reduced fasting blood glucose levels in STZ-induced diabetic mice. Furthermore, α-NETA significantly reduced the expressions of renal injury markers, including serum creatinine, kidney weight/body weight, urine volume, total proteins, and albumin in the urine, and increased creatinine clearance. Periodic acid-Schiff staining also indicated that α-NETA could effectively ameliorate renal injuries in DN mice. In addition, α-NETA inhibited renal inflammation and the expressions of chemerin and CMKLR1 in mice with DN.

CONCLUSION

In summary, our findings suggested that α-NETA has beneficial effects on the management of DN. Specifically, α-NETA effectively ameliorated renal damage and inflammation in a dose-dependent manner in mice with DN. Thus, targeting the chemerin and CMKLR1 axis with α-NETA may be a promising therapeutic strategy for the treatment of DN.

Systems pharmacology-based drug discovery and active mechanism of phlorotannins for type 2 diabetes mellitus by integrating network pharmacology and experimental evaluation

Phlorotannins, polyphenolic compounds that exist only in brown algae, have an effect on T2DM. However, the structure of phlorotannins is complex and diverse, and the complex role of therapeutic targets and active compounds has not been revealed. In this study, the potential targets and pharmacological effects of phlorotannins in the treatment of T2DM were identified based on network pharmacology and enzyme activity inhibition experiment. In total, 15 phlorotannins and 53 associated targets were yielded. Among them, SRC, ESR1, AKT1, HSP90AB1, and AR were defined as core targets. 527 GO biological processes items and 101 KEGG pathways were obtained, including EGFR tyrosine kinase inhibitor resistance, thyroid hormone signaling pathway, AGE-RAGE signaling pathway in diabetic complications, and VEGF signaling pathway. Phlorotannins could enable resistance against T2DM by inflammatory, survival, gene transcription, proliferation, apoptosis, and atherosclerosis. Finally, α-glucosidase inhibition assay and molecular docking proved the effect of selected phlorotannins on T2DM. PRACTICAL APPLICATIONS: Phlorotannins are a kind of polyphenol compounds that only exists in brown algae. Its structure is polymerized by aromatic precursors phloroglucinol (1,3,5-trihydroxybenzene). They have aroused great interest due to their excellent and valuable biological activities. However, the structure of phlorotannins is complex and diverse, and the complex role of therapeutic targets and active compounds has not been revealed. In this study, the potential targets and pharmacological effects of phlorotannins in the treatment of T2DM were determined basis on network pharmacology and enzyme activity inhibition experiment. In conclusion, the results showed the value of phlorotannins treating on T2DM. Moreover, this study has great significance for improving the medicinal value of phlorotannins and screening natural products for the treatment of T2DM.

Urinary chemerin as a potential biomarker for inflammatory bowel disease

Purpose

Systemic levels of the adipokine chemerin are elevated in different inflammatory conditions such as inflammatory bowel disease (IBD). In IBD, chemerin protein expression in colon mucosa is induced and serum chemerin levels are increased. Aim of this study was to identify chemerin protein in human feces and/or urine and to evaluate a possible association with IBD activity.

Materials and methods

Feces and urine of 40 patients with IBD and the respective sera of 34 patients were collected. Chemerin levels were analyzed by immunoblot in feces and urine samples. In addition, enzyme-linked immunosorbent assay (ELISA) was used to measure chemerin in all urine, feces and serum samples of the patients and in urine of 17 healthy controls.

Results

Chemerin was not detectable in 80% of the human feces samples by ELISA. Chemerin in human urine was detected by immunoblot and ELISA. Compared to serum levels, urinary concentration was about 6,000-fold lower. Urinary chemerin did not differ between patients with ulcerative colitis (n = 15) and Crohn's disease (n = 25). Urinary chemerin was not related to its serum levels, did not correlate with serum C-reactive protein level and negatively correlated with serum creatinine. Of note, urinary chemerin of patients with a fecal calprotectin > 500 μg/g was significantly higher compared to patients with lower calprotectin levels and compared to healthy controls. Serum creatinine did not differ between the patient groups.

Conclusion

Urinary chemerin might present a novel non-invasive biomarker for monitoring IBD severity and clinical course.

Carbocistein improves airway remodeling in asthmatic mice

BACKGROUND

The alleviating effects of carbocisteine (S-carboxymethylcysteine, SCMC) have been implicated in chronic obstructive pulmonary disease; however, very little is known about its mechanisms in asthma. In this study, we aimed to investigate the effects of SCMC on airway remodeling in asthmatic mice induced by ovalbumin (OVA).

METHODS

The asthma mouse model was generated by OVA sensitization and stimulation and subsequently intervened by SCMC or dexamethasone. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected from each group of mice. The TGF-β1 levels in BALF were measured by ELISA. Masson's staining was used to detect collagen fiber deposition in mouse airway tissues, while immunohistochemistry and RT-qPCR were conducted to examine the protein and mRNA expression of TGF-β1 in mouse lung airway tissues, respectively. The correlation between TGF-β1 mRNA expression and the area of collagen fiber deposition in airway tissues was analyzed by Pearson's correlation coefficient.

RESULTS

The area of collagen fiber deposition in the airway tissues of asthmatic mice was significantly increased, while SCMC alleviated the collagen fiber deposition in the airway tissues. TGF-β1 expression was significantly elevated in BALF and airway tissues of asthmatic mice, while SCMC inhibited TGF-β1 expression. TGF-β1 expression was significantly and positively correlated with collagen fiber deposition in mouse airway tissues.

CONCLUSIONS

SCMC intervention improves collagen fiber deposition in airway tissues and inhibits TGF-β1 expression in asthmatic mice.

Ectopic Fat Depots: Physiological Role And Impact On Cardiovascular Disease Continuum

Obesity is a non-infectious pandemic. The visceral distribution of adipose tissue is a significant factor in the development of cardiovascular diseases and their complications. Along with the visceral abdominal depot in omentum and subcutaneous tissue, there are other ectopic adipose tissue depots: epicardial adipose tissue (EAT), perivascular adipose tissue (PVAT) and perirenal adipose tissue. This article presents a review of the physiological role and molecular basis of the PVAT and EAT function in healthy, as well as in pathological, conditions; the interaction of adipokines and cytokines, their contribution to the development and progression of cardiovascular diseases. The review discusses well-known facts and controversial issues in this field. Comprehensive investigation of the mechanisms of vascular and myocardial pathology in obese people, along with identification of biomarkers for early prediction of cardiovascular complications, would contribute to the development of targeted preventive measures and choice of therapeutic strategies, which is consistent with the contemporary concept of personalized medicine. We have analyzed domestic and foreign literature sources in eLIBRARY and PubMed scientific libraries for the period of 2001-2020.

Association of serum uromodulin with adipokines in dependence of type 2 diabetes

BACKGROUND

The renal tubular glycoprotein uromodulin is associated with obesity and type 2 diabetes, but the underlying mechanisms are elusive. We investigated the association of serum uromodulin with adipokines and tested the effect modification by diabetes status.

METHODS

The associations of serum uromodulin with eight adipokines were assessed in 795-1080 participants of the KORA F4 study aged 62-81 years using linear regression models adjusted for sex, age, BMI, estimated glomerular filtration rate and diabetes. Significant associations were assessed for effect modification by diabetes status. We further tested using logistic regression whether adjustment for the significant adipokines affected the association of uromodulin with type 2 diabetes.

RESULTS

Serum uromodulin was inversely associated with chemerin and retinol-binding protein-4 after multivariable adjustment (p < 0.001) and Bonferroni correction for multiple testing. No significant association was observed between uromodulin and the other adipokines (leptin, adiponectin, secreted frizzled-related protein 5, progranulin, omentin-1 and vaspin) after correcting for multiple testing. The association of uromodulin with chemerin and retinol-binding protein-4 was stronger in participants with type 2 diabetes than in participants without diabetes (p for interaction < 0.05). However, inclusion of chemerin and retinol-binding protein-4 in logistic regression models did not attenuate the association of serum uromodulin with diabetes.

CONCLUSIONS

Serum uromodulin was inversely associated with the predominantly pro-inflammatory adipokines chemerin and retinol-binding protein-4. The associations were stronger in participants with type 2 diabetes compared to participants without diabetes. However, the association of serum uromodulin with type 2 diabetes was independent of chemerin and retinol-binding protein-4.

The role of vitamin D deficiency and elevated inflammatory biomarkers as risk factors for the progression of diabetic nephropathy in patients with type 2 diabetes mellitus

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. Albuminuria is the most sensitive marker for the early recognition of DN. Therefore, we aimed to study the risk factors of albuminuria as a marker of DN among diabetic patients. The study included 41 patients with type 2 diabetes mellitus (T2DM), 50 type 2 diabetic nephropathy (T2DN) patients with macroalbuminuria, 43 T2DN patients with microalbuminuria and 38 healthy controls. Logistic regression was used to detect the most significant risk factors for albuminuria. A high statistically significant difference was found between the groups regarding age, sex, body mass index (BMI), diabetes mellitus (DM) duration, glucose, glycated haemoglobin (HbA1c), creatinine, glomerular filtration rate (GFR), lipid profile, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), the albumin–creatinine ratio (ACR), vitamin D, total parathyroid hormone (PTH), urea, total calcium and chemerin (p < 0.001). It was found that the duration of DM, BMI, glucose, GFR, total cholesterol (TC), low-density lipoprotein (LDL), TNF-α, IL-6, CRP, ACR, vitamin D, PTH and chemerin are significant albuminuria risk factors in DN. Vitamin D deficiency and associated inflammatory mediators such as chemerin, TNF-α, IL-6 and CRP are the most essential risk factors for albuminuria in T2DM patients.

Chemerin promotes microangiopathy in diabetic retinopathy via activation of ChemR23 in rat primary microvascular endothelial cells

Purpose

The correlation between chemerin and diabetic retinopathy (DR) has been demonstrated previously. We aimed to investigate the potential inflammatory and angiogenic roles of chemerin in DR using rat primary retinal microvascular endothelial cells (RRMECs).

Methods

RRMECs were incubated in low- and high-glucose media, and stable chemerin receptor (ChemR23) knockdown in RRMECs was established by lentiviral infection. Real-time quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and western blotting were employed to investigate the mRNA and protein expression of intercellular adhesion molecule-1 (ICAM-1), vascular endothelial growth factor (VEGF), tumor necrosis factor-α (TNF-α), and the interleukin-6 receptor (IL-6R) to explore the inflammatory and angiogenic effects of chemerin. A scratch assay was employed to evaluate the effect of chemerin on RRMEC migration.

Results

Chemerin and TNF-α markedly increased the mRNA and protein expression of ICAM-1 in RRMECs (p<0.001). ChemR23 knockdown may have decreased the ICAM-1 expression under low- and high-glucose conditions (p<0.001). Even in the ChemR23-knockdown group, TNF-α significantly increased the mRNA and protein levels of ICAM-1 under low- and high-glucose conditions (p<0.001). Chemerin promoted VEGF expression under low- and high-glucose conditions. ChemR23 knockdown markedly decreased VEGF levels under low- and high-glucose conditions (p<0.05) and significantly decreased RRMEC migration (p<0.001).

Conclusions

Chemerin promotes the expression of ICAM-1, the secretion of VEGF, and the migration of RRMECs via the activation of ChemR23.

Fuxin Granules ameliorate diabetic nephropathy in db/db mice through TGF-β1/Smad and VEGF/VEGFR2 signaling pathways

Diabetic nephropathy (DN) is a common disease, and patients often do not have satisfactory treatments. We investigated therapeutic effects of Fuxin Granules(FX) on DN and potential molecular mechanisms. We orally administered doses of FX to db/db mice for 10 weeks and measured total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol. H&E, PAS, Masson, and Oil Red O staining were used to observe the structure of kidneys and calculate indices of kidney function. We used pharmacological analysis to investigate potential mechanisms of FX. Relative mRNA and protein levels in the TGF-β1/Smad, TGF-β1/Smad, and VEGF/VEGFR2 pathways were examined. TC, TG, and LDL-C were markedly reduced, lipid accumulation was low, fibrosis reduced, kidney atrophy improved, kidney lipid droplet number significantly reduced, and glomerular filtration function improved by FX treatment. Multi-channel therapeutic effects in DN through the TGF-β1/Smad and VEGF/VEGFR2 signaling pathways occurred, and FX substantially reduced expression of TGF-β1 in the glomeruli. FX significantly inhibited TGF-β1, Smad2/3 total protein levels, Smad2/3 phosphorylation mRNA levels of TGF-β1, Smad2, and Smad3. eNOS, VEGFA, and VEGFR2 expression was regulated, levels of VEGFA and VEGFR2 were decreased, and FX increased eNOS. FX ameliorated symptoms of DN, resulting in marked improvement in hyperglycemia and hyperlipidemia and optimized structure and function of kidneys in db/db mice. FX efficacy was associated with the TGF-β1/Smad and VEGF/VEGFR2 signaling pathways. We verified this potential mechanism and hope that this study will provide benefits for the clinical treatment of DN.

Based on Network Pharmacology and Molecular Docking to Explore the Underlying Mechanism of Huangqi Gegen Decoction for Treating Diabetic Nephropathy

Background

Huangqi Gegen decoction (HGD), a Chinese herb formula, has been widely used to treat diabetic nephropathy in China, while the pharmacological mechanisms are still unclear. Therefore, the present study aims to explore the underlying mechanism of HGD for treating diabetic nephropathy (DN).

Materials and Methods

Traditional Chinese Medicine Systems Pharmacology Database (TCMSP), UniProt, and SwissTargetPrediction databases were used to search the active ingredients and potential targets of HGD. In addition, multiple disease-related databases were used to collect DN-related targets. Common targets of the protein-protein interaction (PPI) network were established using the STRING database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the DAVID database. At last, AutoDockVina was used to conduct molecular docking verification for the core components and targets.

Results

A total of 27 active ingredients and 354 putative identified target genes were screened from HGD, of which 99 overlapped with the targets of DN and were considered potential therapeutic targets. Further analysis showed that the HGD activity of quercetin, formononetin, kaempferol, isorhamnetin, and beta-sitosterol ingredients is possible through VEGFA, IL6, TNF, AKT1, and TP53 targets involved in TNF, toll-like receptors, and MAPK-related pathways, which have anti-inflammatory, antiapoptosis, antioxidation, and autophagy effects, relieve renal fibrosis and renal cortex injury, and improve renal function, thus delaying the development of DN. The molecular docking results showed that quercetin, formononetin, kaempferol, isorhamnetin, beta-sitosterol had a good binding activity with VEGFA, IL6, TNF, AKT1, and TP53.

Conclusion

This study demonstrated that HGD might take part in the treatment of DN through multicomponent, multitarget, and multichannel combined action.

Antiangiogenic therapy in diabetic nephropathy: A double‑edged sword (Review)

Diabetes and the associated complications are becoming a serious global threat and an increasing burden to human health and the healthcare systems. Diabetic nephropathy (DN) is the primary cause of end-stage kidney disease. Abnormal angiogenesis is well established to be implicated in the morphology and pathophysiology of DN. Factors that promote or inhibit angiogenesis serve an important role in DN. In the present review, the current issues associated with the vascular disease in DN are highlighted, and the challenges in the development of treatments are discussed.

Momordica charantia silver nanoparticles modulate S/JAK/STAT and P13K/Akt/PTEN signalling pathways in the kidney of streptozotocin-induced diabetic rats

Objectives

Diabetes nephropathy (DN) is one of the complications of diabetes mellitus (DM) marked by gradual progressive loss of renal function. SOCS/JAK/STAT and PI3K/Akt/PTEN signalling pathways are among the chain of interactions implicated in the onset, progression and pathology of DN. Momordica charantia (bitter melon) is often used in folk medicine as therapy for DM due to its hypoglycemic properties. This study was designed to evaluate M. charantia silver nanoparticles' therapeutic effect on DN-induced by streptozotocin (STZ) in Wistar rats.

Methods

The M. charantia nanoparticles used was synthesized using the filtrate from the plant methanolic extract added to 1 mM concentration of aqueous silver nitrate. DM was induced in Wistar rats by intraperitoneal injection of STZ (65 mg/kg). The animals' treatment groups were divided into; Diabetic control (65 mg/kg STZ), Control, and groups treated with silver nitrate (10 mg/kg), M. charantia nanoparticles (50 mg/kg), metformin (100 mg/kg), and plant extract (100 mg/kg). Treatment was terminated after 11 days. RT-PCR determined renal mRNA expression of Akt, PI3k, PTEN, TGF-β, JAK2, STAT3, STAT5, SOCS3, SOCS4 and glucokinase (GCK). Consequently, characterized compounds from M. charantia identified from literatures were docked with PI3K, JAK2 and TGF-β and STAT3 to retrieve potential hits.

Results

Oral administration of M. charantia nanoparticles (50 mg/kg) to STZ-induced diabetic untreated rats significantly ((p < 0.05) down-regulated the mRNA expression of Akt, PI3k, TGF-β, JAK2, STAT3 and upregulated the mRNA expression of PTEN, SOCS3 and SOCS4, thus establishing the role of M. charantia nanoparticles in alleviating DN in diabetic rats. Additionally, there was a significant up-regulation of glucose metabolizing gene (glucokinase) upon administering M. charantia nanoparticles. Molecular docking results showed 12 compounds from bitter melon with docking score ranging from -6.114 kcal/mol to -8.221 kcal/mol that are likely to exert anti-diabetic properties.

Conclusion

Observation drawn from this study suggests that M. charantia nanoparticles ameliorate DN through regulation of SOCS/JAK/STAT and PI3K/Akt/PTEN signalling pathways.

Elevated blood urea nitrogen is associated with recurrence of post-operative chronic subdural hematoma

Background

Chronic subdural hematoma (CSDH) is fundamentally treatable with about a 2–31% recurrence rate. Recently, there has been renewed interest in the association between Blood Urea Nitrogen (BUN) and intracranial lesion. Therefore, this paper attempts to show the relationship between BUN and CSDH recurrence.

Methods

A total of 653 CSDH cases with Burr-hole Irrigation (BHI) were enrolled from December 2014 to April 2019. The analyzed parameters included age, gender, comorbidities, laboratory investigations, medication use and hematoma location. The cases were divided into recurrence and non-recurrence groups while postoperative BUN concentration was further separated into quartiles (Q1 ≤ 4.0 mmol/L, 4.0 < Q2 ≤ 4.9 mmol/L, 4.9 < Q3 ≤ 6.4 mmol/L, Q4 > 6.4 mmol/L). Restricted cubic spline regressions and logistic regression models were performed to estimate the effect of BUN on CSDH recurrence.

Results

CSDH recurrence was observed in 96 (14.7%) cases. Significant distinctions were found between recurrence and non-recurrence groups in postoperative BUN quartiles of cases (P = 0.003). After adjusting for the potential confounders, the odds ratio of recurrence was 3.069 (95%CI =1.488–6.330, p = 0.002) for the highest quartile of BUN compared with the lowest quartile. In multiple-adjusted spline regression, a high BUN level visually showed a significantly high OR value of recurrence risk.

Conclusions

Elevated BUN at post-operation is significantly associated with the recurrence of CSDH, and it is indicated that high levels of serum BUN after evacuation may serve as a risk factor for CSDH recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-020-01985-w.

Chemerin as a Driver of Hypertension: A Consideration

The protein chemerin (tazarotene-induced gene, TIG2; RARRES2) is a relatively new adipokine. Many studies support that circulating chemerin levels associate strongly and positively with body mass index, visceral fat, and blood pressure. Here, we focus on the specific relationship of chemerin and blood pressure with the goal of understanding whether and how chemerin drives (pathological) changes in blood pressure such that it could be interfered with therapeutically. We dissect the biosynthesis of chemerin and how current antihypertensive medications change chemerin metabolism. This is followed with a review of what is known about where chemerin is synthesized in the body and what chemerin and its receptors can do to the physiological function of organs important to blood pressure determination (e.g., brain, heart, kidneys, blood vessels, adrenal, and sympathetic nervous system). We synthesize from the literature our best understanding of the mechanisms by which chemerin modifies blood pressure, with knowledge that plasma/serum levels of chemerin may be limited in their pathological relevance. This review reveals several gaps in our knowledge of chemerin biology that could be filled by the collective work of protein chemists, biologists, pharmacologists, and clinicians.

Multiplex Bead Array Assay of a Panel of Circulating Cytokines and Growth Factors in Patients with Albuminuric and Non-AlbuminuricDiabetic Kidney Disease

A panel of cytokines and growth factors, mediating low-grade inflammation and fibrosis, was assessed in patients with type 2 diabetes (T2D) and different patterns of chronic kidney disease (CKD). Patients with long-term T2D (N = 130) were classified into four groups: no signs of CKD; estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² without albuminuria; albuminuria and eGFR ≥60 mL/min/1.73 m²; albuminuria and eGFR <60 mL/min/1.73 m². Thirty healthy subjects were acted as control. Twenty-seven cytokines and growth factors were assessed in serum by multiplex bead array assay. Serum hs-CRP, urinary nephrin, podocine, and WFDC2 were measured by ELISA. Patients with T2D showed elevated IL-1Ra, IL-6, IL-17A, G-CSF, IP-10, MIP-1α, and bFGF levels; concentrations of IL-4, IL-12, IL-15, INF-γ, and VEGF were decreased. IL-6, IL-17A, G-CSF, MIP-1α, and bFGF correlated negatively with eGFR; IL-10 and VEGF demonstrated negative associations with WFDC2; no relationships with podocyte markers were found. Adjusted IL-17A and MIP-1α were predictors of non-albuminuric CKD, IL-13 predicted albuminuria with preserved renal function, meanwhile, IL-6 and hsCRP were predictors of albuminuria with eGFR decline. Therefore, albuminuric and non-albuminuric CKD in T2D patients are associated with different pro-inflammatory shifts in the panel of circulating cytokines.

Astragalus polysaccharides protect renal function and affect the TGF-/Smad signaling pathway in streptozotocin-induced diabetic rats

OBJECTIVES

The objective was to observe the effects of Astragalus polysaccharides on diabetes and on regulation of the TGF-β/Smad signaling pathway.

METHODS

A type 2 diabetic rat model was established with a high-fat diet in combination with low-dose streptozotocin (35 mg/kg). Astragalus polysaccharides were applied as treatment intervention and changes in blood glucose and kidney morphology and function were assessed.

RESULTS

Eight weeks after model establishment, kidney weight as a proportion of total weight (KW/TW) in the high-, medium-, and low-dose Astragalus polysaccharide groups was significantly lower than that in the model group, and the KW/TW value gradually decreased with increasing dose of polysaccharides in each treatment group. Fasting blood glucose in the low- and medium-dose Astragalus polysaccharide groups was numerically lower than that in the model group and fasting blood glucose in rats in the high-dose group was significantly lower than that in the model group. Levels of 24-hour urinary microalbumin, creatinine, blood urea nitrogen, collagens I, III, and IV, α-smooth muscle actin, transforming growth factor-β1, and Smad3 in Astragalus polysaccharide groups (all doses) were significantly lower than those in the model group.

CONCLUSIONS

Astragalus polysaccharide significantly improved blood glucose and protected kidney function in a rat diabetes model.

Sick fat: the good and the bad of old and new circulating markers of adipose tissue inflammation

Adipose tissue (AT) is one of the largest endocrine organs contributing to metabolic homeostasis. The functional pleiotropism of AT depends on its ability to secrete a large number of hormones, cytokines, extracellular matrix proteins and growth factors, all influencing many local and systemic physiological and pathophysiological processes. In condition of chronic positive energy balance, adipocyte expansion, hypoxia, apoptosis and stress all lead to AT inflammation and dysfunction, and it has been demonstrated that this sick fat is a main risk factor for many metabolic disorders, such as type 2 diabetes mellitus, fatty liver, cardiovascular disease and cancer. AT dysfunction is tightly associated with aberrant secretion of bioactive peptides, the adipocytokines, and their blood concentrations often reflect the expression in the AT. Despite the existence of an association between AT dysfunction and systemic pro-inflammatory state, most of the circulating molecules detectable in obese and dysmetabolic individuals do not identify specifically the condition of sick fat. Based on this premise, this review provides a concise overview of "classic" and novel promising adipocytokines associated with AT inflammation and discusses possible critical approaches to their interpretation in clinical practice.

Increased Circulating Chemerin in Relation to Chronic Microvascular Complications in Patients with Type 2 Diabetes

OBJECTIVE

Type 2 diabetes (T2DM) is a global epidemic and increases mortality due to its vascular complications. Chemerin has been found to exert a major role in glucose and lipid metabolism. The aim of this study was to explore the correlation between plasma chemerin levels and microangiopathy in patients with T2DM.

METHODS

A total of 598 T2DM patients were classified into two groups: with and without microvascular complications. Anthropometric parameters and blood pressure were taken. The amounts of glycosylated hemoglobin, glucose, lipid profiles, creatinine, and chemerin concentrations in the blood were determined. The presence and severity of nephropathy, retinopathy, and neuropathy were also evaluated by specific tests.

RESULTS

Plasma levels of chemerin in diabetic subjects with microvascular complications were markedly elevated compared to those without. The number of microvascular complications increased with high plasma chemerin levels. Patients with high chemerin levels had an increased incidence of nephropathy and retinopathy. Furthermore, the chemerin plasma concentrations increased with the progression of diabetic nephropathy with highest values in macroalbuminuria groups. In contrast, no significant difference was observed in plasma chemerin levels between subjects with and without peripheral neuropathy. Pearson correlation analysis showed that plasma chemerin levels were positively related to duration of diabetes, serum creatinine, and 24-hour urine albumin excretion, even after multiple adjustments. Using logistic regression analysis, plasma chemerin concentrations were independently associated with the presence of nephropathy and retinopathy, not neuropathy.

CONCLUSION

This study elucidated a positive correlation between increased chemerin levels and the development of some subtypes of diabetic microangiopathy.

Chemerin/ChemR23 axis promotes inflammation of glomerular endothelial cells in diabetic nephropathy

Diabetic nephropathy (DN) is characterized by inflammation of renal tissue. Glomerular endothelial cells (GEnCs) play an important role in inflammation and protein leakage in urine in DN patients. Chemerin and its receptor ChemR23 are inducers of inflammation. The aim of this study was to investigate the function of chemerin/ChemR23 in GEnCs of DN patients. Immunohistochemical staining and qRT‐PCR were used to measure the expression of chemerin, ChemR23 and inflammatory factors in renal tissues of DN patients. Db/db mice were used as animal model. ChemR23 of DN mice was knocked down by injecting LV3‐shRNA into tail vein. Inflammation, physiological and pathological changes in each group was measured. GEnCs were cultured as an in vitro model to study potential signalling pathways. Results showed that expression of chemerin, ChemR23 and inflammatory factors increased in DN patients and mice. LV3‐shRNA alleviated renal damage and inflammation in DN mice. GEnCs stimulated by glucose showed increased chemerin, ChemR23 and inflammatory factors and decreased endothelial marker CD31. Both LV3‐shRNA and SB203580 (p38 MAPK inhibitor) attenuated chemerin‐induced inflammation and injury in GEnCs. Taken together, chemerin/ChemR23 axis played an important role in endothelial injury and inflammation in DN via the p38 MAPK signalling pathway. Suppression of ChemR23 alleviated DN damage.

Soluble Dipeptidyl Peptidase-4 Levels Are Associated with Decreased Renal Function in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) is strongly expressed in the kidney, and soluble levels of this protein are used as a marker in various chronic inflammatory diseases, including diabetes, coronary artery disease, and cancer. This study examined the association between the serum soluble DPP-4 levels and renal function or cardiovascular risk in patients with type 2 diabetes mellitus.

METHODS

In this retrospective analysis, soluble DPP-4 levels were measured in preserved sera from 140 patients with type 2 diabetes mellitus who had participated in our previous coronary artery calcium (CAC) score study.

RESULTS

The mean±standard deviation soluble DPP-4 levels in our study sample were 645±152 ng/mL. Univariate analyses revealed significant correlations of soluble DPP-4 levels with the total cholesterol (r=0.214, P=0.019) and serum creatinine levels (r=-0.315, P<0.001) and the estimated glomerular filtration rate (eGFR; estimated using the modification of diet in renal disease equation) (r=0.303, P=0.001). The associations of soluble DPP-4 levels with serum creatinine and GFR remained significant after adjusting for age, body mass index, and duration of diabetes. However, no associations were observed between soluble DPP-4 levels and the body mass index, waist circumference, or CAC score.

CONCLUSION

These data suggest the potential use of serum soluble DPP-4 levels as a future biomarker of deteriorated renal function in patients with type 2 diabetes mellitus.

Effects of total flavonoids from Oxytropis falcata Bunge on the SOCS/JAK/STAT inflammatory signaling pathway in the kidneys of diabetic nephropathy model mice

To investigate the effects of total flavonoids from Oxytropis falcata Bunge on the inflammatory signaling pathway suppressor of cytokine signaling (SOCS)/Janus kinase (JAK)/signal transducer and activator of transcription (STAT) in diabetic nephropathy KK-Ay mice. KK-Ay mice were used to establish a diabetic nephropathy model. The general condition of the mice treated with different concentrations of total flavonoids from O. falcata was monitored, respectively. Body weight, blood glucose, 24-h urinary albumin (UAlb), serum creatinine (Cre), blood urea nitrogen (BUN), and uric acid (UA) levels were measured at different time points. Hematoxylin and eosin staining quantitative reverse transcription-polymerase chain reaction and western blotting were used to detect changes in renal tissues and glomerular mesangial cells. Four weeks after model establishment, body weight, blood glucose, and 24 h UAlb significantly increased in KK-Ay mice compared with that in control C57BL/6j mice ( P < 0.05). Compared with non-treated model mice, mice treated with total flavonoids from O. falcata for 4 weeks had significantly decreased serum Cre, BUN, and UA; monocyte chemoattractant protein-1(MCP-1), nuclear factor(NF)-κB, interleukin(IL)-6, and transforming growth factor(TGF)-β1, JAK 1, STAT 3 and STAT 4 mRNA levels; and p-JAK2 and p-STAT1 protein levels and significantly increased SOCS-1 and SOCS-3 protein levels in the kidneys. The treatment effects were dose-dependent and same to in vitro. Our results reflected that total flavonoids from O. falcata relieved renal tissue inflammation in diabetic mice by reducing blood glucose levels and inhibiting JAK/STAT signaling, thereby protecting against the development of diabetic nephropathy.

Chemerin: a multifaceted adipokine involved in metabolic disorders

Metabolic syndrome is a global public health problem and predisposes individuals to obesity, diabetes and cardiovascular disease. Although the underlying mechanisms remain to be elucidated, accumulating evidence has uncovered a critical role of adipokines. Chemerin, encoded by the gene Rarres2, is a newly discovered adipokine involved in inflammation, adipogenesis, angiogenesis and energy metabolism. In humans, local and circulating levels of chemerin are positively correlated with BMI and obesity-related biomarkers. In this review, we discuss both peripheral and central roles of chemerin in regulating body metabolism. In general, chemerin is upregulated in obese and diabetic animals. Previous studies by gain or loss of function show an association of chemerin with adipogenesis, glucose homeostasis, food intake and body weight. In the brain, the hypothalamus integrates peripheral afferent signals including adipokines to regulate appetite and energy homeostasis. Chemerin increases food intake in seasonal animals by acting on hypothalamic stem cells, the tanycytes. In peripheral tissues, chemerin increases cell expansion, inflammation and angiogenesis in adipose tissue, collectively resulting in adiposity. While chemerin signalling enhances insulin secretion from pancreatic islets, contradictory results have been reported on how chemerin links to obesity and insulin resistance. Given the association of chemerin with obesity comorbidities in humans, advances in translational research targeting chemerin are expected to mitigate metabolic disorders. Together, the exciting findings gathered in the last decade clearly indicate a crucial multifaceted role for chemerin in the regulation of energy balance, making it a promising candidate for urgently needed pharmacological treatment strategies for obesity.

Chemerin/chemR23 association with endothelial-mesenchymal transition in diabetic nephropathy

This study was aimed to analyze the association of chemerin/chemR23 with endothelial-mesenchymal transition (EndMT) in the kidney of rats during the progression of diabetic nephropathy (DN). Eighty male Sprague-Dawley rats were randomly distributed to age-matched control and diabetic nephropathy model groups. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ). Morphological changes in the renal tissues were observed after periodic acid-Schiff staining. Chemerin and chemR23 expression was determined by immunohistochemistry. Co-expression of α-smooth muscle actin (α-SMA) and CD31 was determined by immunofluorescence double-labeling. Expression of all these markers was analyzed by Western blotting. Expression of chemerin, chemR23, and transforming growth factor-β1 (TGF-β1) genes at mRNA level was determined by qRT-PCR. Mild glomerular hypertrophy was observed at 4 weeks and mild glomerular basement membrane thickening and mesangial matrix proliferation at 12 weeks. Immunohistochemistry showed much higher levels of chemerin and chemR23 in diabetic rats compared with the control group. Expression of chemerin, chemR23, and α-SMA proteins increased with disease progression, while CD31 protein expression decreased. Expression of chemerin, chemR23, and TGF-β1 mRNAs also increased. α-SMA and CD31 co-expression increased with disease progression from 4 weeks. Spearman correlation analysis showed that chemerin mRNA levels correlated positively with Chem R23, TGF-β1, α-SMA expression, and CD31 and α-SMA double-positive cell numbers, but negatively with CD31 protein expression. In conclusion, chemerin expression correlates with EndMT in DN model rats.