Inflammation in diabetic kidney disease

Expression levels of serum vasohibin-1 and other biomarkers in type 2 diabetes mellitus patients with different urinary albumin to creatinine ratios

AIM

To determine the serum levels of vasohibin (VASH)-1 and other biomarkers in type 2 diabetes mellitus (T2DM) patients with different urinary albumin to creatinine ratios (UACR), and correlate VASH-1 expression with the inflammation and fibrosis in diabetic kidney disease (DKD).

METHODS

A total of 697 T2DM patients were stratified into four groups: N-UAlb (UACR <30 mg/g with normal blood pressure, n = 144), M-UAlb (UACR 30-300 mg/g with normal blood pressure, n = 143), L-UAlb (UACR >300 mg/g with normal blood pressure, n = 126), and L-UAlb+HP (UACR >300 mg/g with hypertension, n = 134). In addition, 150 healthy subjects were included as normal controls (NC). In addition to recording the age and duration of diabetes, the serum levels of VASH-1, silent information regulator factor 2-related enzyme 1 (sirtuin-1, SIRT1), hypoxia inducible factor 1α (HIF1α), vascular endothelial growth factor (VEGF), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), and the erythrocyte sedimentation rate (ESR) were measured. Clinical parameters related to UACR and VASH-1 were analyzed by one-way ANOVA, Pearson correlation and ridge regression analysis.

RESULTS

The UACR, VASH-1, glycosylated hemoglobin (HbA1c), ESR, CRP, VEGF, HIF1α, TNF-α and TGF-β1 levels in all patient groups were significantly higher, and SIRT1 levels were lower compared to the NC group. Pearson correlation analysis showed that UACR and VASH-1 levels were positively correlated with HbA1c, ESR, CRP, VEGF, HIF1α, TNF-α and TGF-β1, and negatively with SIRT1. Ridge regression analysis showed that every serological marker was an independent factor affecting UACR.

CONCLUSION

Serum VASH-1 may be associated with the expression of renal inflammation and fibrosis-related factors, and have a potential connection with DKD.

Long noncoding RNA: an emerging player in diabetes and diabetic kidney disease

Diabetic kidney disease (DKD) is among the most common complications of diabetes mellitus (DM), and remains the leading cause of end-stage renal diseases (ESRDs) in developed countries, with no definitive therapy yet available. It is imperative to decipher the exact mechanisms underlying DKD and identify novel therapeutic targets. Burgeoning evidence indicates that long non-coding RNAs (lncRNAs) are essential for diverse biological processes. However, their roles and the mechanisms of action remain to be defined in disease conditions like diabetes and DKD. The pathogenesis of DKD is twofold, so is the principle of treatments. As the underlying disease, diabetes per se is the root cause of DKD and thus a primary focus of therapy. Meanwhile, aberrant molecular signaling in kidney parenchymal cells and inflammatory cells may directly contribute to DKD. Evidence suggests that a number of lncRNAs are centrally involved in development and progression of DKD either via direct pathogenic roles or as indirect mediators of some nephropathic pathways, like TGF-β1, NF-κB, STAT3 and GSK-3β signaling. Some lncRNAs are thus likely to serve as biomarkers for early diagnosis or prognosis of DKD or as therapeutic targets for slowing progression or even inducing regression of established DKD. Here, we elaborated the latest evidence in support of lncRNAs as a key player in DKD. In an attempt to strengthen our understanding of the pathogenesis of DKD, and to envisage novel therapeutic strategies based on targeting lncRNAs, we also delineated the potential mechanisms of action as well as the efficacy of targeting lncRNA in preclinical models of DKD.

Kidney Disease in Diabetes Mellitus: Cross-Linking between Hyperglycemia, Redox Imbalance and Inflammation

Chronic hyperglycemia is the key point of macro- and microvascular complications associated with diabetes mellitus. Excess glucose is responsible for inducing redox imbalance and both systemic and intrarenal inflammation, playing a critical role in the pathogenesis of diabetic kidney disease, which is currently the leading cause of dialysis in the world. The pathogenesis of the disease is complex, multifactorial and not fully elucidated; many factors and mechanisms are involved in the development, progression and clinical outcomes of the disease. Despite the disparate mechanisms involved in renal damage related to diabetes mellitus, the metabolic mechanisms involving oxidative/inflammatory pathways are widely accepted. The is clear evidence that a chronic hyperglycemic state triggers oxidative stress and inflammation mediated by altered metabolic pathways in a self-perpetuating cycle, promoting progression of cell injury and of end-stage renal disease. The present study presents an update on metabolic pathways that involve redox imbalance and inflammation induced by chronic exposure to hyperglycemia in the pathogenesis of diabetic kidney disease.

The correlation between blood oxidative stress and sialic acid content in diabetic patients with nephropathy, hypertension, and hyperlipidemia

This clinical study was designed to find out the correlation between oxidative stress and sialic acid (SA) content of plasma and RBCs in patients with type 2 diabetes. We evaluated SA concentration and oxidative stress biomarkers in healthy subjects and diabetic patients with and without complications in a cross-sectional survey. Significant changes in oxidative stress biomarkers and RBC-SA were revealed in the diabetic patients compared to those in the healthy group. Plasma SA significantly increased with an increase in lipid peroxidation of RBCs (LPO-RBC) (P < 0.001) in the diabetic patients without complication. RBC-SA significantly decreased with an elevation in LPO-RBC (P < 0.001) in all the diabetic patients and those with nephropathy. There was no significant correlation between plasma and RBC-SA and other oxidative stress biomarkers in the diabetic subjects. In multiple logistic regression analysis, RBC-SA was independently related to LPO-RBC in all the diabetic patients and those with nephropathy. We conclude that the induction of LPO-RBC in diabetic patients and those with nephropathy may influence the SA decomposition of RBC membrane, thereby altering its functions and transporter activities. Therefore, LPO-RBC and SA levels in RBCs can be used for prediction of diabetic nephropathy, and further studies to evaluate other factors contributing to desialylation of RBC membrane are justified.

Celastrol attenuates renal injury in diabetic rats via MAPK/NF-κB pathway

The purpose of this study was to investigate the renal protective effect of celastrol on diabetic rats. Furthermore, the mechanism of its action was discussed whether it was related to MAPK/NF-κB signaling pathway. There were a total of 36 rats. Six rats were randomly chosen as the control group. The remaining 30 rats were given 1% streptozotocin intraperitoneal injection (50 mg/kg) and were randomly divided into five groups: the model control group, the low-dose celastrol group, the high-dose celastrol group, the Tripterygium wilfordii polyglycosides group, and the MAPK/NF-κB inhibitor group. After 4 weeks of continuous administration, 24-hr urine volume, urinary protein, blood urea nitrogen, and serum creatinine content were observed, and hematoxylin-eosin (HE) staining of the kidney and liver were evaluated. p38MAPK was designated by immunohistochemical method, and NF-κB p65 in renal tissue was detected by western blotting. Our results showed that celastrol could not only reduce contents of creatinine and urea nitrogen in blood but also reduce excretion of urinary protein in diabetic rats, improve renal pathological injury, and down-regulate the expression of p38MAPK and NF-κB p65. In conclusion, celastrol could protect kidney of diabetic rats by regulating the signal pathway of MAPK/NF-κB, inhibiting inflammation and delaying renal injury.

Thalidomide decreases high glucose-induced extracellular matrix protein synthesis in mesangial cells via the AMPK pathway

A previous study demonstrated the renal-protective effect of thalidomide (Thd) in diabetic nephropathy rats through the activation of the adenosine monophosphate-activated protein kinase (AMPK) and inhibition of the nuclear factor κB (NF-κB)/monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog signaling pathways. The association between AMPK inactivation and high glucose (HG)-induced meningeal cell (MC) proliferation and extracellular matrix (ECM) accumulation via NF-κB and TGF-β1 signaling remains unknown. The aim of the current study was to demonstrate the effects of Thd on cell proliferation and ECM expression in HG-cultured MCs and the underlying mechanisms. HG-cultured human MCs were treated with Thd. Cell proliferation was measured by MTT assay and quantification of cell proliferation was based on the measurement of bromodeoxyuridine incorporation. The differences in TGF-β1, fibronectin and MCP-1 protein expression levels were detected via ELISA and western blot analysis. The AMPK signaling pathway was also examined by western blot analysis in MCs. Compound C, an AMPK inhibitor and AICAR (5-aminoimidazole-4-carboxamide 1β-D-ribofuranoside), an AMPK agonist, were used to analyze the functional role of AMPK in MCs. Cell proliferation was significantly decreased in HG-cultured MCs following treatment with high concentrations of Thd (100 and 200 µg/ml) for 24 h compared with the HG-cultured MC group. Thd suppressed the inflammatory processes in HG-induced MCs. These effects were partially mediated through the activation of AMPK and inhibition of the NF-κB/MCP-1 signaling pathways. Taken together, these results suggest that Thd may have therapeutic potential in diabetic renal injury via the AMPK signaling pathway.

Coreopsis tinctoria Nutt ameliorates high glucose-induced renal fibrosis and inflammation via the TGF-β1/SMADS/AMPK/NF-κB pathways

BACKGROUND

Coreopsis tinctoria Nutt is an ethnomedicine widely used in Xinjiang, China. It is consumed as a herbal tea by local Uyghur people to treat high blood pressure and diarrhea. Our previous study confirmed that the ethyl acetate extract of Coreopsis tinctoria (AC) had a protective effect on diabetic nephropathy (DN) in an in vivo experiment. Here we aim to elucidate the protective mechanism of AC and marein, the main ingredient in Coreopsis tinctoria on renal fibrosis and inflammation in vitro under high glucose (HG) conditions.

METHODS

A HG-induced barrier dysfunction model in rat mesangial cells (HBZY-1) was established. The cells were exposed to AC and marein and/or HG for 24 h. Then, the renal protective effects of AC and marein via transforming growth factor-β1 (TGF-β1)/Smads, AMP-activated kinase protein (AMPK), and nuclear factor kappa beta (NF-κB) signaling were assessed.

RESULTS

Both AC and marein suppressed rat mesangial cell hyperplasia and significantly attenuated the expression of HG-disrupted fibrotic and inflammatory proteins in HBZY-1 cells. It was also confirmed that AC and marein remarkably attenuated HG-induced renal inflammation and fibrosis by regulating the AMPK, TGF-β1/Smads, and NF-κB signaling pathways.

CONCLUSION

These results indicated that AC and marein may delay the progression of DN, at least in part, by suppressing HG-induced renal inflammation and fibrosis. Marein may be one of the bioactive compounds in AC.

The effect of A1 adenosine receptor in diabetic megalin loss with caspase-1/IL18 signaling

PURPOSE

In our previous study, exacerbation of albuminuria was observed in A1 adenosine receptor knockout (A1AR^-/-) mice with diabetic nephropathy (DN), but the mechanism was unclear. Here, we investigated the relationship of megalin loss and albuminuria, to identify the protective effect of A1AR in megalin loss associated albuminuria by inhibiting pyroptosis-related caspase-1/IL-18 signaling of DN.

METHODS

We successfully collected DN patients' samples and built diabetes mice models induced by streptozotocin. Megalin, cubilin, and A1AR expression were detected in kidney tissue samples from DN patients and mice through immunohistochemical and immunofluorescent staining. A1AR, caspase-1, interleukin-18 (IL-18) expression were analyzed using Western blotting in wild-type and A1AR ^-/- mice. Human renal proximal tubular epithelial cells (PTC) were cultured with high glucose to observe the effect of A1AR agonist and antagonist on caspase-1/IL-18 and megalin injury.

RESULTS

The loss of megalin, co-localized with A1AR at PTC, was associated with the level of albuminuria in diabetic patients and mice. The injury of megalin-cubilin was accompanied with the A1AR upregulation (1.30±0.1 vs 0.98±0.2, P=0.042), the caspase-1 (1.33±0.1 vs 1.0±0.2, P=0.036), and IL-18 (1.26±0.2 vs 0.96±0.2, P=0.026) signaling activation in mice with DN. More severe pathological injury, 24 hrs urine albumin excretion (170.8±4.1 μg/d vs 132.0±2.9 μg/d vs 17.9±2.8 μg/d, P<0.001) and megalin-cubilin loss were observed in A1AR ^-/- DN mice with more pronounced caspase-1 (1.52±0.03 vs 1.20±0.01, P=0.017) and IL-18 (1.42±0.02 vs 1.21±0.02, P=0.018) secretion. High glucose could stimulate the secretion of caspase-1 (1.72 times, P≤0.01) and IL-18 (1.64 times, P≤0.01), which was abolished by A1AR agonist and aggravated by A1AR antagonist.

CONCLUSION

A1AR played a protective role in proximal tubular megalin loss associated albuminuria by inhibiting the pyroptosis-related caspase-1/IL-18 signaling in DN.

Group 2 Innate Lymphoid Cells Participate in Renal Fibrosis in Diabetic Kidney Disease Partly via TGF-β1 Signal Pathway

AIM

To explore the role of group 2 innate lymphoid cells (ILC2s) in the pathogenesis of renal fibrosis in diabetic kidney disease (DKD).

METHODS

The proportion of ILC2s and the levels of Th2 cytokines (IL-4, IL-5, and IL-13) in the peripheral blood of normal control subjects (NC) or patients with type 2 diabetes mellitus (DM), early diabetic kidney disease (DKD1), or late diabetic kidney disease (DKD2) were analyzed by flow cytometry and ELISA. The expression of transforming growth factor-β1 (TGF-β1), fibronectin (FN), collagen1, IL-4Rα, and IL-13Rα1 in renal tubular epithelial cells (HK-2) induced by IL-4, IL-13, or high glucose was analyzed by ELISA or qPCR.

RESULTS

The proportion of ILC2s and the levels of IL-4, IL-5, and IL-13 were significantly increased in DKD patients and were positively correlated with the severity of DKD (P < 0.05). The expression of TGF-β1, FN, and collagen1 was significantly upregulated in HK-2 cells induced by IL-4 or IL-13 (P < 0.05). Moreover, the IL-4Rα and IL-13Rα1 mRNA in HK2 cells were increased followed by high glucose alone or combined with IL-4 or IL-13, but the differences were not statistically significant (P > 0.05). However, compared with high-glucose stimulation alone, the expression of TGF-β1, FN, and collagen1 was significantly increased in HK-2 cells induced by high glucose combined with IL-4 or IL-13 (P < 0.05).

CONCLUSIONS

ILC2s may participate in renal fibrosis in DKD partly via TGF-β1 signal pathway.

N6 -(2-hydroxyethyl)-adenosine from Cordyceps cicadae protects against diabetic kidney disease via alleviation of oxidative stress and inflammation

This study investigated the kidney-protective ability of N⁶ -(2-hydroxyethyl)-adenosine (HEA) in alloxan-induced diabetic rats. Diabetes was induced in the rats by the administration of alloxan monohydrate (150 mg/kg, i.p) and treated with HEA for 6 weeks. Diabetic rats displayed marked increase in blood glucose, serum creatinine (Scr), and blood urea nitrogen (BUN), in addition to high excretion of urinary protein and albumin. Furthermore, diabetic rats showed decreased renal levels of glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and increased malondialdehyde (MDA) as well as renal concentrations of pro-inflammatory mediators (TNF-α, IL-6, IL-1β, and TGF-β1). Treatment of diabetic rats with HEA (20 and 40 mg/kg) significantly increased the renal antioxidant level, reduced the levels of blood glucose, Scr, BUN, urinary protein, albumin, and pro-inflammatory mediators in a dose-dependent fashion. Histological evaluation of the kidney of diabetic rats indicated that HEA also ameliorated glomerular and tubular changes. PRACTICAL APPLICATIONS: HEA is a bioactive constituent isolated from Cordyceps cicadae and has been shown to possess antihyperglycemic, kidney protective, antioxidant, and antiinflammatory effects in diabetic rats. HEA stimulated the antioxidant enzymes' activities in the kidney tissues as well as reduced pro-inflammatory mediators, indicating its antidiabetic and renoprotective effects in diabetic models. The results showed that HEA attenuated oxidative stress and inflammation in kidney tissues.

Impact of bariatric surgery on cardiovascular and renal complications of diabetes: a focus on clinical outcomes and putative mechanisms

INTRODUCTION

Cardiovascular and renal disease accounts for a substantial proportion of the morbidity and mortality associated with obesity and type 2 diabetes mellitus (T2DM). Bariatric surgery is associated with improved long-term cardiovascular and renal outcomes.

AREAS COVERED

All major case-control, cohort, and randomized controlled trial studies of bariatric surgery in adults with T2DM were screened and data on prespecified cardiovascular and renal outcomes collated. Bariatric surgery reduces all-cause mortality and risk of cardiovascular disease, albuminuria and progressive chronic kidney disease. Patients with poorer glycemic control and established microvascular disease preoperatively may stand to benefit the most from the surgical approach. Reduced sympathetic drive, remission of glomerular hypertension, enhanced natriuresis, gut microbiota shifts, reduced systemic and renal inflammation, improved lipoprotein profiles, and reductions in chronic cardiac remodeling may all be implicated.

EXPERT COMMENTARY

Ongoing RCTs of bariatric surgery selectively recruiting patients with class 1 obesity and established microvascular complications of diabetes will help to better characterize which subgroups of patients benefit most from this effective therapy.

Ursolic acid improves diabetic nephropathy via suppression of oxidative stress and inflammation in streptozotocin-induced rats

Inflammation plays a pivotal role in the pathogenesis of diabetic nephropathy (DN). Overexpression of inflammatory chemokine and cytokines is involved in the development of DN. Ursolic acid (UA), a common pentacyclic triterpenoid compound, has been reported to have myriad benefits and medicinal properties. However, its protective effects against renal injury in streptozotocin (STZ)-induced diabetic rats have not been firmly established. In the current report, we investigated whether UA inhibits oxidative stress and inflammation in the kidneys of STZ-induced diabetic rats. Diabetes mellitus (DM) was induced by STZ (40 mg/ kg, i.v.). Animals were randomly divided into control group (normal saline, i.g.), DN group (normal saline, i.g.), DN + UA group (35 mg/kg UA + normal saline, i.g.) and DN + telmisartan group (12 mg/kg telmisartan + normal saline, i.g.). Fasting blood glucose (FBG) levels were monitored at regular intervals. The administration of compounds started at 5th week and lasted for 8 weeks. At the beginning of 13th week, rats were humanely euthanized, KW/BW, BUN, SCr, SOD and MDA were measured. Histopathological changes in renal tissue were observed after hematoxylin-eosin (HE) staining. Furthermore, the expressions of TNF-α, MCP-1 and IL-1β in kidney were determined by immunohistochemistry and western blot. Our results showed that UA significantly lowered the levels of FBG, KW/BW, BUN, SCr and MDA in diabetic rats. Additionally, the SOD activity in UA treated group was higher than that in DN group. Furthermore, renal structural abnormalities and the elevation of TNF-α, MCP-1 and IL-1β expression level were blocked by the administration of UA. In conclusion, our data demonstrate that UA could be well used as a protective agent to counter renal dysfunction - through antioxidant and anti-inflammatory effects.

Influence of IL-6, IL-10, IFN-γ and TNF-α genetic variants on susceptibility to diabetic kidney disease in type 2 diabetes mellitus patients

BACKGROUND

Data from previous studies on the role of inflammatory cytokines as biomarkers for diabetic kidney disease (DKD) are contradictory. The association of a particular inflammatory cytokine single nucleotide polymorphism (SNP) with susceptibility to DKD has not been consistently replicated. We aimed to investigate the utility of inflammatory cytokines as biomarkers for DKD in type 2 diabetes mellitus (T2DM) patients. Association of inflammatory cytokine gene SNPs with the development of DKD was also explored.

SUBJECTS AND METHODS

One hundred and fifty-nine Kuwaiti subjects were recruited in this study, including 50 T2DM patients without DKD, 67 diabetic DKD patients and 42 healthy subjects. Plasma levels of interleukin-6 (IL-6), IL-10, interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) were measured by enzyme-linked immunosorbent assays. Nine SNPs, including 2 SNPs in IL-6, 3 SNPs in IL-10, 1 SNP in IFN-γ and 3 SNPs in TNF-α, were genotyped using TaqMan SNP genotyping assays.

RESULTS

Diabetic DKD patients showed higher IL-6, IL-10, IFN-γ and TNF-α levels than those without DKD. Diabetic DKD patients had a significantly higher frequency of IL-10 - 1082 A allele than those without DKD (p = 0.001). No significant association of IL-6 - 174/-597 haplotypes with DKD risk was detected (p = 0.188). Distribution of IL-10 - 592/-819/-1082 haplotypes differ significantly between T2DM patients with/without DKD (p = 0.014). Diabetic DKD patients had a significantly lower frequency of IL-10 - 592C/-819C/-1082G haplotype than those without DKD (p = 0.002).

CONCLUSIONS

Although inflammatory cytokine genotypes and, more importantly, haplotypes may have the potential to identify those patients at risk of DKD, hence, improving DKD predisposition prediction, further investigations regarding their real clinical significance is warranted in a large cohort of patients.

Herba Artemisiae Capillaris Extract Prevents the Development of Streptozotocin-Induced Diabetic Nephropathy of Rat

Diabetic nephropathy (DN) is a major cause of end-stage renal disease throughout the world; until now there is no specific drug available. In this work, we use herba artemisiae capillaris extract (HACE) to alleviate renal fibrosis characterized by the excessive accumulation of extracellular matrix (ECM) in rats, aiming to investigate the protective effect of the HACE on DN. We found that the intragastric treatment of high-dose HACE could reverse the effect of streptozotocin not only to decrease the level of blood glucose and blood lipid in different degree but also further to improve renal functions. It is worth mentioning that the effect of HACE treatment was comparable to the positive drug benazepril. Moreover, we found that HACE treatment could on one hand inhibit oxidative stress in DN rats through regulating enzymatic activity for scavenging reactive oxygen species and on the other hand increase the ECM degradation through regulating the activity of metalloproteinase-2 (MMP-2) and the expression of tissue transglutaminase (tTG), which explained why HACE treatment inhibited ECM accumulation. On the basis of above experimental results, we conclude that HACE prevents DN development in a streptozotocin-induced DN rat model, and HACE is a promising candidate to cure DN in clinic.

Role of peroxisome proliferator-activated receptor-gamma activation on visfatin, advanced glycation end products, and renal oxidative stress in obesity-induced type 2 diabetes mellitus

The present study focused on the role of peroxisome proliferator-activated receptor-gamma (PPAR-γ) activation on renal oxidative damages, serum visfatin, and advanced glycation end products (AGEs) in high-fat diet (HFD)-induced type 2 diabetes mellitus. Following the institutional animal ethics committee guidelines, Wistar rats were categorized into five groups: group 1: fed on a normal rat diet; group 2: HFD-induced obese rats (HFD for 8 weeks); group 3: HFD-fed rats treated with rosiglitazone (RSG; 3 mg/kg orally for 7 days); group 4: T2DM rats induced by HFD and low dose of streptozotocin (i.p. 35 mg/kg); group 5: T2DM rats treated with RSG (3 mg/kg orally for 7 days). Serum levels of AGEs and visfatin, renal damage, and oxidative stress were analyzed. Results showed that HFD-induced obesity and T2DM caused an elevated blood glucose, serum AGEs, visfatin, insulin, urea, creatinine, and tissue malondialdehyde, whereas a decreased catalase and superoxide dismutase activity were observed. The PPAR-γ activation via agonist restored these changes. Our findings suggest that AGEs and visfatin possess an important role in the progression of renal oxidative stress, which can be reduced by the PPAR-γ agonist that impede deleterious effects of HFD and HFD-induced T2DM on renal damage.

Oridonin protects against the inflammatory response in diabetic nephropathy by inhibiting the TLR4/p38-MAPK and TLR4/NF-κB signaling pathways

Inflammation plays a pivotal role in the development and progression of diabetic nephropathy (DN). Oridonin (Ori), a component isolated from Rabdosia rubescens, possesses remarkable anti-inflammatory, immunoregulatory and antitumor properties. However, the renoprotective effects of Ori and the underlying molecular mechanisms have not been explored in DN. In this study, we aimed to investigate the protective effects and potential mechanisms responsible for the anti-inflammatory effects of Ori in diabetes-induced renal injury in vivo and in vitro. Our results showed that Ori significantly attenuated diabetes-induced renal injury and markedly decreased urinary protein excretion levels, serum creatinine concentrations and blood urea nitrogen concentrations in rats. Ori also significantly alleviated infiltration of inflammatory cells (cluster of differentiation (CD)68) in kidney tissues and reduced the levels of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β and monocyte chemotactic protein 1 (MCP-1), both in vivo and in vitro. TLR4 is a principal mediator of innate immune and inflammatory responses and participates in the development of DN. Our molecular studies indicated that Ori administration significantly down-regulated TLR4 overexpression in DN. Additional studies were conducted to investigate the effect of Ori on the p38-mitogen-activated protein kinase (p38-MAPK) and nuclear factor (NF)-κB pathways. The results showed that Ori inhibited IκBα, p65, and p38 phosphorylation, as well as NF-κB DNA-binding activity. In conclusion, these results demonstrated that Ori exerts protective effects in diabetes-induced renal injury in vivo and in vitro. These effects may be ascribed to its anti-inflammatory and modulatory effects on the TLR4/p38-MAPK and TLR4/NF-κB signaling pathways.

Renal-protective effect of thalidomide in streptozotocin-induced diabetic rats through anti-inflammatory pathway

Background

Diabetic nephropathy (DN) is a major microvascular complication in diabetes. An increasing body of evidence has shown that DN is related to chronic inflammation, kidney hypertrophy, and fibrosis. While thalidomide has been shown to have anti-inflammatory and antifibrotic effects, the effects of thalidomide on the pathogenesis of DN are unclear. This study was undertaken to explore whether thalidomide has renal-protective effects in diabetic rats.

Methods

Male Sprague Dawley rats were injected intraperitoneally with 50 mg/kg streptozotocin to induce diabetes. Diabetic rats were treated with thalidomide (200 mg/kg/d) for 8 weeks, and then blood and urine were collected for measurement of renal function-related parameters. Histopathology, immunohistochemistry, enzyme-linked immunosorbent assay, and Western blot analyses were performed to assess renal proinflammatory cytokines, fibrotic protein, and related signaling pathways.

Results

Diabetic rats exhibited obvious renal structural and functional abnormalities, as well as renal inflammation and fibrosis. Compared with diabetic control rats, those treated with thalidomide showed significantly improved histological alterations and biomarkers of renal function, as well as reduced expression of renal inflammatory cytokines, including NF-κB and MCP-1. Furthermore, renal fibrotic proteins, such as TGF-β1, TβRII, TβRI, smad3, collagen IV, and fibronectin were also remarkably suppressed. Treatment with thalidomide markedly stimulated the phosphorylation of AMPKα.

Conclusion

In this study, thalidomide suppressed the inflammatory and fibrotic processes in DN. These effects were partly mediated by the activation of AMPKα, and inhibition of the NF-κB/MCP-1 and TGF-β1/Smad signaling pathways. These results suggest that thalidomide may have therapeutic potential in diabetic renal injury through the anti-inflammatory pathway.

Previous Exercise Training Reduces Markers of Renal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Female Rats

The aim of this study is to evaluate the effects of regular moderate exercise training initiated previously or after induction of diabetes mellitus on renal oxidative stress and inflammation in STZ-induced diabetic female rats. For this purpose, Wistar rats were divided into five groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD), trained diabetic (TD), and previously trained diabetic (PTD). Only the PTD group was submitted to treadmill running for 4 weeks previously to DM induction with streptozotocin (40 mg/kg, i.v). After confirming diabetes, the PTD, TD, and TC groups were submitted to eight weeks of exercise training. At the end of the training protocol, we evaluated the following: glycosuria, body weight gain, plasma, renal and urinary levels of nitric oxide and thiobarbituric acid reactive substances, renal glutathione, and immunolocalization of lymphocytes, macrophages, and nuclear factor-kappa B (NF-κB/p65) in the renal cortex. The results showed that exercise training reduced glycosuria, renal TBARS levels, and the number of immune cells in the renal tissue of the TD and PTD groups. Of note, only previous exercise increased weight gain and urinary/renal NO levels and reduced NF-κB (p65) immunostaining in the renal cortex of the PTD group. In conclusion, our study shows that exercise training, especially when initiated previously to diabetes induction, promotes protective effects in diabetic kidney by reduction of renal oxidative stress and inflammation markers in female Wistar rats.

Calcium dobesilate may alleviate diabetes‑induced endothelial dysfunction and inflammation

Diabetic kidney disease (DKD) is a leading cause of end‑stage renal disease. However, the pathogenesis of DKD remains unclear, and no effective treatments for the disease are available. Thus, there is an urgent need to elucidate the pathogenic mechanisms of DKD and to develop more effective therapies for this disease. Human umbilical vein endothelial cells (HUVECs) were cultured using different D‑glucose concentrations to determine the effect of high glucose (HG) on the cells. Alternatively, HUVECs were incubated with 100 µmol/l calcium dobesilate (CaD) to detect its effects. The authors subsequently measured HUVEC proliferation via cell counting kit‑8 assays. In addition, HUVEC angiogenesis was investigated via migration assays and fluorescein isothiocyanate (FITC)‑labelled bovine serum albumin (BSA) permeability assays. The content or distribution of markers of endothelial dysfunction [vascular endothelial growth factor (VEGF), VEGF receptor (R) and endocan) or inflammation [intercellular adhesion molecule (ICAM)‑1, monocyte chemotactic protein (MCP)‑1 and pentraxin‑related protein (PTX3)] was evaluated via reverse transcription‑quantitative polymerase chain reaction and western blotting. HG treatment induced increased in VEGF, VEGFR, endocan, ICAM‑1, MCP‑1 and PTX3 mRNA and protein expression in HUVECs. HG treatment for 24 to 48 h increased cell proliferation in a time‑dependent manner, but the cell proliferation rate was decreased at 72 h of HG treatment. Conversely, CaD inhibited abnormal cell proliferation. HG treatment also significantly enhanced HVUEC migration compared to the control treatment. In contrast, CaD treatment partially inhibited HUVEC migration compared to HG exposure. HG‑treated HUVECs exhibited increased FITC‑BSA permeability compared to control cells cultured in medium alone; however, CaD application prevented the HG‑induced increase in FITC‑BSA permeability and suppressed HG‑induced overexpression of endothelial markers (VEGF, VEGFR‑2, endocan) and inflammation markers (ICAM‑1, MCP‑1, PTX3) in HUVECs. CaD has angioprotective properties and protects endothelial cells partly by ameliorating HG‑induced inflammation. The current results demonstrated the potential applicability of CaD to the treatment of diabetic nephropathy, particularly during the early stages of this disease.

Serotonin and Its Receptor as a New Antioxidant Therapeutic Target for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a widespread chronic microvascular complication of diabetes mellitus (DM), affects almost 30-50% of patients, and represents a leading cause of death of DM. Serotonin or 5-hydroxytryptamine (5-HT) is a multifunctional bioamine that has crucial roles in many physiological pathways. Recently, emerging evidence from experimental and clinical studies has demonstrated that 5-HT is involved in the pathogenesis of diabetic vascular complications. The 5-HT receptor (5-HTR) antagonists exert renoprotective effects by suppressing oxidative stress, suggesting that 5-HTR can be used as a potential target for treating DKD. In this review, therefore, we summarize the published information available for the involvement of 5-HT and 5-HTR antagonists in the pathogenesis of various diabetic complications with a particular focus of DKD. We conclude that 5-HTR is a potential therapeutic target for treating DKD, as it has been successfully applied in animal models and has currently being investigated in randomized and controlled clinical trials.

WITHDRAWN: Salvianolate attenuates renal fibrosis in rat models of diabetic nephropathy by inhibiting inflammation and oxidative stress mechanisms

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Contribution of serum adipocyte fatty acid-binding protein levels to the presence of microalbuminuria in a Chinese hyperglycemic population

AIMS/INTRODUCTION

Individuals with type 2 diabetes mellitus are vulnerable to micro- and macrovascular complications in the presence of microalbuminuria. Adipocyte fatty acid-binding protein (A-FABP) was proposed as an indicator for albuminuria in patients with diabetes. The present study aimed to explore the associations between serum A-FABP levels and microalbuminuria in the hyperglycemic population.

MATERIALS AND METHODS

Serum A-FABP levels were detected using sandwich enzyme-linked immunosorbent assay. Microalbuminuria was identified by urinary albumin-to-creatinine ratio (UACR), when the value was between 30-300 mg/g. The participants were divided into the subgroups based on sex and the status of impaired glucose regulation or newly diagnosed type 2 diabetes mellitus.

RESULTS

A total of 939 participants, consisting of 436 men and 503 women, were enrolled. Serum levels of A-FABP were much higher in participants with microalbuminuria than those without microalbuminuria. This result held true for all subgroups (all P < 0.05). For Spearman's correlation analyses, serum A-FABP levels showed a positive relationship with the UACR in men and women (both P < 0.01). Multiple stepwise regression analysis showed that serum A-FABP levels were independently and positively correlated with UACR in both sexes (men: standardized β = 0.256, P < 0.001; women: standardized β = 0.155, P = 0.001). This relationship remained significant in every subgroup (all P < 0.01).

CONCLUSIONS

For hyperglycemic individuals, serum A-FABP levels increased in the presence of microalbuminuria. Serum A-FABP levels were identified as an independent factor positively associated with the UACR.

Maresin 1 Mitigates High Glucose-Induced Mouse Glomerular Mesangial Cell Injury by Inhibiting Inflammation and Fibrosis

Background. Inflammation and fibrosis are the important pathophysiologic processes in diabetic nephropathy (DN). Maresin 1 is a potential anti-inflammatory lipid mediator, which has displayed powerful proresolving activities. Aim. We determine whether maresin 1 has protective effect on mouse glomerular mesangial cells (GMCs) induced by high glucose. Methods. We cultured GMCs stimulated by high glucose and categorized as follows: normal glucose group (5.6 mmol/L), high glucose group (30 mmol/L), mannitol group, maresin 1 intervention group (1, 10, and 100 nmol/L), maresin 1 and normal glucose group, and the N-acetylcysteine (NAC) intervention group (10 μmol/L NAC). After 24 h, the expression of ROS, NLRP3, caspase-1, procaspase-1, IL-1β, and pro-IL-1β was detected by western-blot, RT-PCR, and immunofluorescence. After 48 h, the expression of TGF-β1 and FN was detected by RT-PCR and ELISA. Results. Compared with normal glucose group, the expression of ROS, NLRP3, caspase-1, IL-1β, TGF-β1, and FN increased in high glucose group (P < 0.05), but it decreased after the treatment of maresin 1 in different concentrations. On the contrary, the expression of procaspase-1 and pro-IL-1β protein was restrained by high glucose and enhanced by maresin 1 in a dose-dependent manner (P < 0.05). Conclusion. Maresin 1 can inhibit NLRP3 inflammasome, TGF-β1, and FN in GMCs; it may have protective effect on DN by mitigating the inflammation and early fibrosis.

Diabetes-Induced Reactive Oxygen Species: Mechanism of Their Generation and Role in Renal Injury

Diabetes induces the onset and progression of renal injury through causing hemodynamic dysregulation along with abnormal morphological and functional nephron changes. The most important event that precedes renal injury is an increase in permeability of plasma proteins such as albumin through a damaged glomerular filtration barrier resulting in excessive urinary albumin excretion (UAE). Moreover, once enhanced UAE begins, it may advance renal injury from progression of abnormal renal hemodynamics, increased glomerular basement membrane (GBM) thickness, mesangial expansion, extracellular matrix accumulation, and glomerulosclerosis to eventual end-stage renal damage. Interestingly, all these pathological changes are predominantly driven by diabetes-induced reactive oxygen species (ROS) and abnormal downstream signaling molecules. In diabetic kidney, NADPH oxidase (enzymatic) and mitochondrial electron transport chain (nonenzymatic) are the prominent sources of ROS, which are believed to cause the onset of albuminuria followed by progression to renal damage through podocyte depletion. Chronic hyperglycemia and consequent ROS production can trigger abnormal signaling pathways involving diverse signaling mediators such as transcription factors, inflammatory cytokines, chemokines, and vasoactive substances. Persistently, increased expression and activation of these signaling molecules contribute to the irreversible functional and structural changes in the kidney resulting in critically decreased glomerular filtration rate leading to eventual renal failure.

Urinary inflammatory cytokines as indicators of kidney damage in type 2 diabetic patients

BACKGROUND

The aim of this study was to investigate whether urinary levels of interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) are altered in normoalbuminuric patients with type 2 diabetes mellitus (T2DM), and whether these cytokines are able to identify diabetic kidney disease (DKD) among these patients.

METHODS

This study included 125 T2DM patients classified into 3 groups according to urinary albumin/creatinine ratio (uACR): uACR <10mg/g creatinine, uACR 10-30mg/g creatinine and uACR >30mg/g creatinine. Urinary inflammatory cytokines were measured.

RESULTS

The urinary IL-6 concentrations increased from uACR <10 (97.2±26.4pg/ml) to uACR 10-30 (113.6±28.0pg/ml) and to uACR >30mg/g creatinine (163.5±25.6pg/ml) (P<0.05 and P<0.001, respectively) patients. The urinary IL-10 concentrations decreased in these uACR ranges [100.0 (58.0-141.0) pg/ml vs. 62.0 (54.5-71.5) pg/ml vs. 42.0 (32.0-48.0) pg/ml] (P<0.05 and P<0.001, respectively). All urinary cytokines demonstrated good ability to identify DKD (areas under curves >0.9).

CONCLUSIONS

Urinary inflammatory cytokines, especially IL-6 and IL-10, may assist in the identification of DKD in T2DM patients, even in the absence of micro- and macroalbuminuria.

Effects of a GSK-3β inhibitor on the renal expression levels of RANK, RANKL and NF-κB in a rat model of diabetic nephropathy

The present study aimed to investigate the effects of glycogen synthase kinase-3β (GSK-3β) on the expression levels of receptor activator of nuclear factor (NF)-κB (RANK), RANK ligand (RANKL) and NF-κB in the renal tissues of rats modeling diabetic nephropathy (DN). The rats were allocated at random into three groups, as follows: Normal control group (NC), the DN model group (DNM group) and the DN model lithium chloride (LiCl) intervention group (DNI group). Urinary proteins were examined by staining with the Coomassie Brilliant Blue dye for 24 h. Histochemical analyses of kidney tissue sections were conducted using hematoxylin and eosin staining, after which the kidney pathology of the rats was observed. In addition, the mRNA and protein expression levels of GSK-3β, RANK, RANKL and NF-κB in the renal tissues were detected using reverse transcription-quantitative polymerase chain reaction and immunohistochemistry, respectively. As compared with the NC group, the level of urinary protein was significantly increased in the DNM group (P<0.05); however, as compared with the DNM Group, the level of urinary protein at 12 weeks was significantly decreased in the DNI group (P<0.05). As compared with the NC group, marked pathological changes were detected, and the mRNA and protein expression levels of GSK-3β, RANK, RANKL and NF-κB were significantly increased, in the renal tissues of the DNM group. Conversely, pathological alterations in the renal tissues were attenuated, and the mRNA and protein expression levels of GSK-3β, RANK, RANKL and NF-κB were significantly decreased (P<0.05), in the DNI group, as compared with the DNM group. The results of the present study suggested that GSK-3β, RANK, RANKL and NF-κB may be crucially involved in the development of DN, and that LiCl may effectively attenuate DN by reducing the expression levels of GSK-3β, RANK, RANKL and NF-κB.

Involvement of the NF-κB signaling pathway in the renoprotective effects of isorhamnetin in a type 2 diabetic rat model

The aim of the present study was to investigate the renoprotective effects of isorhamnetin (ISO) in type 2 diabetic rats and its effects on the nuclear factor-κB (NF-κB) signaling pathway, which is associated with diabetic nephropathy. The type 2 diabetic rat model was established by a high-fat diet plus streptozocin injection and the rats were subsequently treated with two dosages of ISO, respectively. The levels of blood glucose were determined. Urinary osteopontin, kidney injury molecule-1 (KIM-1) and albumin were measured to evaluate the renal function of the rats. Renal NF-κB signaling activity was assessed by measuring the levels of NF-κB p65, phospho-NF-κB p65, inhibitor of NF-κB (IκBα) and phospho-IκBα, and the NF-κB p65 DNA-binding activity. Downstream inflammatory mediators [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-β1 (TGF-β1)] of the NF-κB signaling pathway were investigated to evaluate the renal inflammatory response. Renal levels of malondialdehyde and total superoxide dismutase were detected to access the oxidative stress. Furthermore, glomerular mesangial cells (GMCs) were treated with lipopolysaccharide and ISO. In the cellular experiment, the NF-κB signaling activity, levels of TNF-α, IL-1β, IL-6, ICAM-1 and TGF-β1, and oxidative stress were also investigated. The results showed that ISO decreased the levels of urinary osteopontin, KIM-1 and albumin. ISO also inhibited the NF-κB signaling activity, decreased the production of inflammatory mediators and attenuated oxidative stress in diabetic rats and GMCs. The present investigations revealed that ISO had ameliorative effects on diabetes-induced renal damage and the activity may be associated with the negative regulation of NF-κB signaling pathway.

Beneficial effect of lycopene on anti-diabetic nephropathy through diminishing inflammatory response and oxidative stress

Lycopene is widely used for nutritional supplementation, but the potential benefits in diabetic nephropathy (DN) remains unknown. This study aimed to highlight the therapeutic prospect of lycopene against streptozotocin (STZ)-induced kidney injury in mice. During the process of the experiments, biochemical kits were employed to determine the diabetes-metabolic parameters in STZ-lesioned mice. Routine pathological and ultrastructural observations were screened for the histological changes of kidney tissue. Moreover, immunohistochemical staining was used to investigate the inflammatory conditions expressed in kidney tissue. Furthermore, intrarenal heme oxygenase 1 (HO-1) mRNA level was assayed via RT-PCR and Western blot analyses. The results showed that lycopene alleviated the lesioned signs of DN mice induced by STZ, accompanied with the increase in body weight, reduced serum concentrations of blood sugar and low-density lipoprotein cholesterol (LDL-C), elevated high-density lipoprotein cholesterol (HDL-C) level, and the decrease in urine protein content. In addition, oxidative defense patterns in the kidneys of DN mice were ameliorated, as shown in augmented bioactivities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and in turn lowered malondialdehyde (MDA) content. The immunohistochemical experiment exhibited that lycopene intake contributed to attenuation of nuclear factor-kappa B (NF-κB) and tumor necrosis factor alpha (TNF-α) expressions in kidney tissue. Moreover, intrarenal HO-1 level was up-regulated in the presence of lycopene. Our findings provide the evidence that lycopene protects kidney cells from STZ-induced lesions via inhibiting NF-κB signal pathway for anti-inflammation and attenuating oxidative stress for anti-dysmetabolism.

Renal Protection by Genetic Deletion of the Atypical Chemokine Receptor ACKR2 in Diabetic OVE Mice

In diabetic nephropathy (DN) proinflammatory chemokines and leukocyte infiltration correlate with tubulointerstitial injury and declining renal function. The atypical chemokine receptor ACKR2 is a chemokine scavenger receptor which binds and sequesters many inflammatory CC chemokines but does not transduce typical G-protein mediated signaling events. ACKR2 is known to regulate diverse inflammatory diseases but its role in DN has not been tested. In this study, we utilized ACKR2(-/-) mice to test whether ACKR2 elimination alters progression of diabetic kidney disease. Elimination of ACKR2 greatly reduced DN in OVE26 mice, an established DN model. Albuminuria was significantly lower at 2, 4, and 6 months of age. ACKR2 deletion did not affect diabetic blood glucose levels but significantly decreased parameters of renal inflammation including leukocyte infiltration and fibrosis. Activation of pathways that increase inflammatory gene expression was attenuated. Human biopsies stained with ACKR2 antibody revealed increased staining in diabetic kidney, especially in some tubule and interstitial cells. The results demonstrate a significant interaction between diabetes and ACKR2 protein in the kidney. Unexpectedly, ACKR2 deletion reduced renal inflammation in diabetes and the ultimate response was a high degree of protection from diabetic nephropathy.

FK506 ameliorates podocyte injury in type 2 diabetic nephropathy by down-regulating TRPC6 and NFAT expression

Diabetic nephropathy (DN) is the leading cause of end-stage renal failure, and podocyte injury plays a major role in the development of DN. In this study, we investigated whether tacrolimus (FK506), an immunosuppressor, can attenuate podocyte injury in a type 2 diabetic mellitus (T2DM) rat model with DN. Transmission electron microcopy was used to morphologically evaluate renal injury. The urinary albumin (UAL), creatinine clearance rate (Ccr) and major biochemical parameters, including glucose, insulin, serum creatinine (Scr), urea nitrogen, total cholesterol (CHO) and triglyceride (TG), were examined 12 weeks after the administration of FK506. The expressions of the canonical transient receptor potential 6 (TRPC6), nuclear factor of activated T-cells (NFAT) and nephrin were detected by Western blotting and qPCR. In the rat model of DN, the expressions of TRPC6 and NFAT were significantly elevated compared with the normal rat group; however, the treatment with FK506 normalized the increased expression of TRPC6 and NFAT and attenuated podocyte ultrastructure injury. UAL, Ccr and the biochemical parameters were also improved by the use of FK506. In cell experiments, FK506 improved the decreased expression of nephrin and suppressed the elevated expression of both TRPC6 and NFAT caused by high glucose in accordance with TRPC6 blocker U73122. Our results demonstrated that FK506 could ameliorate podocyte injury in T2DM, which may be related to suppressed expressions of TRPC6 and NFAT.

Genetic, epigenetic and protein analyses of intercellular adhesion molecule 1 in Malaysian subjects with type 2 diabetes and diabetic nephropathy

AIMS

Recent research has implicated that the inflammation may be a key pathophysiological mechanism in diabetic nephropathy (DN). Intercellular adhesion molecule 1 (ICAM-1) is an acute phase marker of inflammation. In the present study, we carried out genetic, epigenetic and protein analyses of ICAM-1 in a Malaysian population, including normal glucose tolerance (NGT) subjects and type 2 diabetes (T2D) patients with or without DN in order to evaluate its role in DN.

METHODS

Analyses of DNA polymorphism and methylation in the ICAM1 gene were performed with TaqMan allelic discrimination and pyrosequencing, respectively. Plasma ICAM-1 levels were determined using an enzyme-linked immune-sorbent assay kit.

RESULTS

We found that the ICAM1 K469E(A/G) polymorphism (rs5498) was significantly associated with DN. Particularly, 86.1% of T2D patients with DN carried heterozygous genotype compared to the patients without DN (68.6%). Furthermore, plasma ICAM-1 levels were increased from NGT subjects to T2D patients without and with DN (P<0.001). The NGT subjects carrying heterozygous genotype had significantly lower plasma ICAM-1 levels compared to the K469(A/A) genotype carriers (P=0.009). In the ICAM1 gene promoter, DNA methylation levels of CpG sites were low, and no association of the ICAM1 DNA methylation alteration with DN was detected.

CONCLUSION

The present study provided evidence that the ICAM1 K469E(A/G) polymorphism with high heterozygous index and elevation of plasma ICAM-1 levels were associated with DN in a Malaysian population. Further prospective study of ICAM-1 protein according to the ICAM1 K469E(A/G) genotypes is necessary for predicting the susceptibility to T2D and DN.

The anti-inflammatory and antifibrotic effects of Coreopsis tinctoria Nutt on high-glucose-fat diet and streptozotocin-induced diabetic renal damage in rats

Background

Diabetic nephropathy is a serious complication of diabetes whose development process is associated with inflammation, renal hypertrophy, and fibrosis. Coreopsis tinctoria Nutt, traditionally used as a healthcare tea, has anti-inflammatory, anti-hyperlipidemia, and glycemic regulation activities. The aim of our study was to investigate the renal protective effect of ethyl acetate extract of C. tinctoria Nutt (AC) on high-glucose–fat diet and streptozotocin (STZ)-induced diabetic rats.

Methods

A diabetic rat model was induced by high-glucose–fat diet and intraperitoneal injection of 35 mg/kg STZ. After treatment with AC at a daily dose of 150, 300 or, 600 mg/kg for 4 weeks, metabolic and renal function parameters of serum and urine were examined. Degree of renal damage, renal proinflammatory cytokines, and fibrotic protein expression were analyzed by histopathology and immunohistochemistry. Renal AMP-activated protein kinase (AMPK) and transforming growth factor (TGF)-β1/Smad signaling pathway were determined by western blotting.

Results

Diabetic rats showed obvious renal dysfunction, inflammation and fibrosis. However, AC significantly reduced levels of blood glucose, total cholesterol, triglyceride, blood urea nitrogen, serum creatinine and urinary albumin, as well as expression of kidney proinflammatory cytokines of monocyte chemoattractant protein-1 and intercellular adhesion molecule-1. AC also ameliorated renal hypertrophy and fibrosis by reducing fibronectin and collagen IV and suppressing the TGF-β1/Smad signaling pathway. Meanwhile, AMPKα as a protective cytokine was markedly stimulated by AC.

Conclusion

In summary, AC controls blood glucose, inhibits inflammatory and fibrotic processes, suppresses the TGF-β1/Smad signaling pathway, and activates phosphorylation of AMPKα in the kidneys, which confirms the protective effects of AC in the early stage of diabetic kidney disease.

Lipopolysaccharide challenge significantly influences lipid metabolism and proteome of white adipose tissue in growing pigs

Background

White adipose tissue is recognized as a highly active organ, which is closely related to a large number of physiological and metabolic processes besides storing triglycerides. However, little is known regarding the response of adipose tissue to acute inflammation. Therefore, in this study we employed growing pigs to investigate the changes of lipid metabolism and proteome in white adipose tissue after lipopolysaccharide (LPS) stimulation as a model for bacterial infection.

Methods

The expression of lipid metabolism and inflammation related genes was determined by quantitative real-time polymerase chain reaction. Label-free proteomics analysis was used to investigate changes of the protein profile in white adipose tissue and western blot was used to verify changes of selected adipokines.

Results

The results indicated that LPS significantly increased the expression of toll-like receptor (TLR) 2/4 pathway-related genes and pro-inflammatory factors. Lipid metabolism related genes, including acetyl-CoA carboxylase 1 (ACACA), fatty acid synthase (FASN), stearoyl-CoA desaturase (SCD), uncoupling protein 2 (UCP2), and 11 β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), were down-regulated and the lipolytic enzyme activity was decreased after LPS injection. Proteome analysis revealed 47 distinct proteins with > 2-fold changes. The down-regulation of two proteins (cAMP-dependent protein kinase type II-alpha regulatory subunit and β-tubulin) has been verified by western blot analysis. In addition, the abundance of two adipokines (adiponectin and zinc-α2-glycoprotein) was significantly increased after LPS injection.

Conclusion

In conclusion, LPS challenge can cause acute inflammation in white adipose tissue. Concurrently, lipid metabolism was significantly suppressed and the abundance of several proteins changed in white adipose tissue. The results provide new clues to understand the adipose dysfunction during inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-015-0067-5) contains supplementary material, which is available to authorized users.

Management of glycemia in diabetic patients with stage IV and V chronic kidney disease

Diabetic kidney disease is a leading cause of end-stage kidney disease worldwide. Data suggest that prevention of progression to end-stage may lie in excellent blood glucose control; however, as kidney disease progresses, the risk of hypoglycemia increases, due to unpredictable insulin kinetics and altered pharmacokinetics of hypoglycemic agents. In addition, whole classes of hypoglycemic agents become contraindicated and regimens must be adjusted for declining kidney function. There is no consensus regarding the best therapy for the patient with advanced chronic kidney disease. In the best of circumstances, the care of these patients will involve intensive monitoring, with the input of a team of health care providers creating a coordinated care plan, including dietary advice and a drug regimen tailored to the specific issues faced by the individual patient. An open dialogue is necessary at all times, as patients may become frustrated and attempt self-treatment using over the counter alternatives.

Diabetic Kidney Disease: Pathophysiology and Therapeutic Targets

Diabetes is a worldwide epidemic that has led to a rise in diabetic kidney disease (DKD). Over the past two decades, there has been significant clarification of the various pathways implicated in the pathogenesis of DKD. Nonetheless, very little has changed in the way clinicians manage patients with this disorder. Indeed, treatment is primarily centered on controlling hyperglycemia and hypertension and inhibiting the renin-angiotensin system. The purpose of this review is to describe the current understanding of how the hemodynamic, metabolic, inflammatory, and alternative pathways are all entangled in pathogenesis of DKD and detail the various therapeutic targets that may one day play a role in quelling this epidemic.

Ameliorative effect of chrysin on adenine-induced chronic kidney disease in rats

Chrysin (5, 7- dihydroxyflavone) is a flavonoid with several pharmacological properties that include antioxidant, anti-inflammatory and antiapoptotic activities. in this work, we investigated some effects of three graded oral doses of chrysin (10, 50 and 250 mg/kg) on kidney structure and function in rats with experimental chronic renal disease (CKD) induced by adenine (0.25% w/w in feed for 35 days), which is known to involve inflammation and oxidative stress. Using several indices in plasma, urine and kidney homogenates, adenine was found to impair kidney function as it lowered creatinine clearance and increased plasma concentrations of creatinine, urea, neutrophil gelatinase-associated lipocalin and N-Acetyl-beta-D-glucosaminidase activity. Furthermore, it raised plasma concentrations of the uremic toxin indoxyl sulfate, some inflammatory cytokines and urinary albumin concentration. Renal morphology was severely damaged and histopathological markers of inflammation and fibrosis were especially increased. In renal homogenates, antioxidant indices, including superoxide dismutase and catalase activities, total antioxidant capacity and reduced glutathione were all adversely affected. Most of these adenine – induced actions were moderately and dose -dependently mitigated by chrysin, especially at the highest dose. Chrysin did not cause any overt adverse effect on the treated rats. The results suggest that different doses of chrysin produce variable salutary effects against adenine-induced CKD in rats, and that, pending further pharmacological and toxicological studies, its usability as a possible ameliorative agent in human CKD should be considered.

Endoplasmic Reticulum Stress in the Diabetic Kidney, the Good, the Bad and the Ugly

Diabetic kidney disease is the leading worldwide cause of end stage kidney disease and a growing public health challenge. The diabetic kidney is exposed to many environmental stressors and each cell type has developed intricate signaling systems designed to restore optimal cellular function. The unfolded protein response (UPR) is a homeostatic pathway that regulates endoplasmic reticulum (ER) membrane structure and secretory function. Studies suggest that the UPR is activated in the diabetic kidney to restore normal ER function and viability. However, when the cell is continuously stressed in an environment that lies outside of its normal physiological range, then the UPR is known as the ER stress response. The UPR reduces protein synthesis, augments the ER folding capacity and downregulates mRNA expression of genes by multiple pathways. Aberrant activation of ER stress can also induce inflammation and cellular apoptosis, and modify signaling of protective processes such as autophagy and mTORC activation. The following review will discuss our current understanding of ER stress in the diabetic kidney and explore novel means of modulating ER stress and its interacting signaling cascades with the overall goal of identifying therapeutic strategies that will improve outcomes in diabetic nephropathy.