Taxus chinensis ameliorates diabetic nephropathy through down-regulating TGF-β1/Smad pathway

Scopoletin alleviates high glucose-induced toxicity in human renal proximal tubular cells via inhibition of oxidative damage, epithelial-mesenchymal transition, and fibrogenesis

BACKGROUND

Recent years of evidence suggest the crucial role of renal tubular cells in developing diabetic kidney disease. Scopoletin (SCOP) is a plant-based coumarin with numerous biological activities. This study aimed to determine the effect of SCOP on renal tubular cells in developing diabetic kidney disease and to elucidate mechanisms.

METHODS AND RESULTS

In this study, SCOP was evaluated in vitro using renal proximal tubular (HK-2) cells under hyperglycemic conditions to understand its mechanism of action. In HK-2 cells, SCOP alleviated the high glucose-generated reactive oxygen species (ROS), restored the levels of reduced glutathione, and decreased lipid peroxidation. High glucose-induced alteration in the mitochondrial membrane potential was markedly restored in the SCOP-treated cells. Moreover, SCOP significantly reduced the high glucose-induced apoptotic cell population in the Annexin V-FITC flow cytometry study. Furthermore, high glucose markedly elevated the mRNA expression of fibrotic and extracellular matrix (ECM) components, namely, transforming growth factor (TGF)-β, alfa-smooth muscle actin (α-SMA), collagen I, and collagen III, in HK-2 cells compared to the untreated cells. SCOP treatment reduced these mRNA expressions compared to the high glucose-treated cells. Collagen I and TGF-β protein levels were also significantly reduced in the SCOP-treated cells. Further findings in HK-2 cells revealed that SCOP interfered with the epithelial-mesenchymal transition (EMT) in the high glucose-treated HK-2 cells by normalizing E-cadherin and downregulating the vimentin and α-SMA proteins.

CONCLUSIONS

In conclusion, SCOP modulates the high glucose-generated renal tubular cell oxidative damage and accumulation of ECM components and may be a promising molecule against diabetic nephropathy.

Plasma MCP-1 and TGF-β1 Levels are Associated with Kidney Injury in Children with Congenital Anomalies of the Kidney and Urinary Tract

Congenital anomalies of the kidney and urinary tract (CAKUT) are primarily causal for end-stage renal disease and have significant implications for long-term survival. A total of 39 healthy controls and 94 children with chronic kidney disease (CKD) were enrolled (3-12 years old as children, 13-18 years old as adolescents), who were divided into CAKUT and Non-CAKUT according to the etiology of CKD. CKD group was further classified according to estimating glomerular filtration rate (eGFR). Circulating levels of inflammatory markers such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemokine-1 (MCP-1), and transforming growth factor-β1 (TGF-β1) were analyzed. The relationship between these inflammatory markers with eGFR and the kidney injury parameter (urine protein) was investigated to assess their potential as early markers of disease progression. All circulating levels of these inflammatory cytokines were increased in CKD patients (including CAKUT and Non-CAKUT) compared with healthy subjects. The circulating levels of MCP-1 and TGF-β1 were increased in CAKUT adolescents compared with CAKUT children. In CAKUT children, levels of MCP-1 and TGF-β1 increased as CKD progressed, and MCP-1 and TGF-β1 were negatively and significantly correlated with eGFR and positively with urine protein. MCP-1 and TGF-β1 may contribute to the early detection of CKD and disease stage/progression in CAKUT children.

Promising therapeutic mechanism for Chinese herbal medicine in ameliorating renal fibrosis in diabetic nephropathy

Diabetic nephropathy (DN) is one of the most serious chronic microvascular abnormalities of diabetes mellitus and the major cause of uremia. Accumulating evidence has confirmed that fibrosis is a significant pathological feature that contributes to the development of chronic kidney disease in DN. However, the exact mechanism of renal fibrosis in DN is still unclear, which greatly hinders the treatment of DN. Chinese herbal medicine (CHM) has shown efficacy and safety in ameliorating inflammation and albuminuria in diabetic patients. In this review, we outline the underlying mechanisms of renal fibrosis in DN, including oxidative stress (OS) generation and OS-elicited ASK1-p38/JNK activation. Also, we briefly summarize the current status of CHM treating DN by improving renal fibrosis. The treatment of DN by inhibiting ASK1 activation to alleviate renal fibrosis in DN with CHM will promote the discovery of novel therapeutic targets for DN and provide a beneficial therapeutic method for DN.

Quality evaluation of compounds in leaves of six Taxus species based on UPLC-MS/MS and chemometrics

Introduction: Taxus species are used as medicinal plants all over the world. The leaves of Taxus species are sustainable medicinal resources that are rich in taxoids and flavonoids. However, traditional identification methods cannot effectively identify Taxus species on the basis of leaces used as raw medicinal materials, because their appearance and morphological characteristics are almost the same, and the probability of error identification increases in accordance with the subjective consciousness of the experimenter. Moreover, although the leaves of different Taxus species have been widely used, their chemical components are similar and lack systematic comparative research. Such a situation is challenging for quality assessment. Materials and methods: In this study, ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry combined with chemometrics was applied for the simultaneous determination of eight taxoids, four flavanols, five flavonols, two dihydroflavones, and five biflavones in the leaves of six Taxus species, namely, T. mairei, T. chinensis, T. yunnanensis, T. wallichiana, T. cuspidata, and T. media. Chemometric methods, including hierarchical cluster analysis, principal component analysis, orthogonal partial least squares-discriminate analysis, random forest iterative modeling, and fisher linear discriminant analysis, were utilized to differentiate and evaluate the six Taxus species. Results: This proposed method exhibited good linearity (R ² = 0.9999-0.9972) with a lower quantification limits of 0.94-3.05 ng/mL for all analytes. The intra- and inter-day precisions were within 6.83%. Six compounds, namely, 7-xylosyl-10-deacetyltaxol, ginkgetin, rutin, aromadendrin, 10-deacetyl baccatin III, and epigallocatechin, were identified through chemometrics for the first time. These compounds can be used as important chemical markers to distinguish the above six Taxus species rapidly. Conclusion: This study established a method for determination of the leaves of six Taxus species, and revealing the differences in the chemical components of these six Taxus species.

Liuwei Dihuang Pill Attenuates Diabetic Nephropathy by Inhibiting Renal Fibrosis via TGF-β/Smad2/3 Pathway

Among all the complications of diabetes, diabetic nephropathy is a significant factor causing the end-stage renal disease associated with high death rates. Current treatment fails to produce an ideal outcome. Thus, searching for a new preventive drug is urgently needed. Liuwei Dihuang pill (LDP), a popular ancient Chinese medicine (TCM) prescription, has been applied to treat DN-like syndromes according to TCM theory. Here, we had established an animal model with DN and LDP therapy was put into use to assess its therapeutic effect in vivo. Our data showed that oxidative stress and TGF-β/Smad2/3 pathway-induced renal fibrosis could be observed in the DN animal model. However, the treatment of LDP impeded the generation of ROS and attenuated renal fibrosis-related proteins in damaged kidneys through interference in the TGF-β/Smad3 pathway. Our results indicated that LDP attenuated oxidative stress, accompanied by preventing the production of renal fibrosis through inhibiting the TGF-β/Smad2/3 pathway.

An Overview of the Posttranslational Modifications and Related Molecular Mechanisms in Diabetic Nephropathy

Diabetic nephropathy (DN), a common diabetic microvascular complication, is characterized by its complex pathogenesis, higher risk of mortality, and the lack of effective diagnosis and treatment methods. Many studies focus on the diagnosis and treatment of diabetes mellitus (DM) and have reported that the pathophysiology of DN is very complex, involving many molecules and abnormal cellular activities. Given the respective pivotal roles of NF-κB, Nrf2, and TGF-β in inflammation, oxidative stress, and fibrosis during DN, we first review the effect of posttranslational modifications on these vital molecules in DN. Then, we describe the relationship between these molecules and related abnormal cellular activities in DN. Finally, we discuss some potential directions for DN treatment and diagnosis. The information reviewed here may be significant in the design of further studies to identify valuable therapeutic targets for DN.

Phytochemicals against anti-diabetic complications: targeting the advanced glycation end product signaling pathway

The role of advanced glycation end products (AGEs) is not limited to diabetes and diabetes-related complications. There are multiple modulators, including the receptor for advanced glycation end products, high mobility group box 1, glyoxalase 1, nuclear factor-kappa B, tumor necrosis factor-α, chronic unpredictable stress, reactive oxygen species, and inflammatory cytokines, which interact with AGE signaling and control diabetes, modulating these interacting modulators. The progression of diabetes, as well as related complications, can be controlled and treated. Natural products rich in bioactive constituents can interact with AGEs and their related mediators through various signaling cascades, thereby controlling and preventing the progression of diabetes. This review provides a deeper assessment of the signaling pathway, interactions between phytochemicals and AGEs, and its mediators, to develop a multifold therapeutic approach to prevent and treat diabetes and its related complications.

Probiotics ameliorates glycemic control of patients with diabetic nephropathy: A randomized clinical study

OBJECTIVE

This research aimed to explore the effects of probiotic administration on glycemic control and renal function in patients with diabetic nephropathy (DN).

METHODS

The 101 participants were randomly divided into two treatment groups and 76 patients were included in the final analysis. In 76 patients with diabetic nephropathy of type 2 diabetes, a randomized double-blind and placebo-controlled clinical trial was conducted to evaluate the administration of 3.2 × 109  CFU probiotic supplements per day (Bifidobacterium bifidum, 1.2 × 109  CFU, Lactobacillus acidophilus 4.2 × 109  CFU, Streptococcus thermophilus 4.3 × 109  CFU) for 12 weeks on glycemic control of patients, including fasting blood glucose, 2 h postprandial blood glucose, glycosylated hemoglobin (HbA1c), microalbuminuria/creatinine (mAlb/Cr) and estimated glomerular filtration rate (eGFR) levels. The placebo group daily received empty capsules filled with starch.

RESULTS

After 12 weeks, the administration of probiotics demonstrated a significant reduction in fasting blood glucose (10.68 ± 3.24 mmol/L before vs. 7.81 ± 2.77 mmol/L after, p < 0.05), HbA1c (8.19 ± 1.60% before vs. 7.32 ± 1.20% after, p < 0.05) and mAlb/Cr (101.60 ± 22.17 mg/g before vs. 67.53 ± 20.11 mg/g after, p < 0.05), while only mAlb/Cr level was significantly lower in the probiotic group than in the placebo group after intervention (67.53 ± 20.11 mg/g vs. 87.71 ± 23.01, p < 0.05). Meanwhile, there was no significant reduction of 2 h postprandial blood glucose level (18.95 ± 5.23 mmol/L vs. 17.35 ± 6.28 mmol/L, p = 0.24) and eGFR (84.34 ± 6.97 ml/min vs. 82.8 ± 8.72 ml/min, p = 0.45) in patients before and after probiotic intake. In addition, the placebo group failed to show any significant change of these parameters.

CONCLUSION

This clinical study revealed probiotic administration could ameliorate glycemic control of patients with diabetic nephropathy, potentiating its therapeutic potential in clinical application.

Smad3 signalling affects high glucose-induced podocyte injury via regulation of the cytoskeletal protein transgelin

Aim

The aim of the present study was to characterize the role of Smad3 signalling on high glucose‐induced podocyte injury.

Methods

Synchronized conditionally immortalized mouse podocyte cell line (MPC5) cells were treated with either D‐glucose alone or D‐glucose plus the Smad3 inhibitor SIS3. The distribution of F‐actin and transgelin in a high glucose‐induced model of podocyte injury were examined by immunofluorescence. Levels of transgelin and Smad3 signalling proteins in MPC5 cells were determined by Western blot.

Results

A disordered distribution of F‐actin, as well as co‐localization of F‐actin and transgelin, was observed in podocytes exposed to high glucose. Increased levels of transgelin were first observed 10 minutes after treatment with glucose, suggesting that this protein is sensitive to hyperglycaemic injury. Levels of phosphorylated Smad3 and cleaved caspase 3 increased significantly with glucose stimulation. Moreover, expression of the downstream protein c‐Myc, but not JAK1/STAT3, was induced in conditions of high glucose. The Smad3‐specific inhibitor SIS3 prevented the effects of high glucose on Smad3 phosphorylation, expression of transgelin and c‐Myc, caspase 3 cleavage and cytoskeletal organization. Expression of the tumour suppressor protein p15^INK4B increased after podocyte injury but was unaffected by Smad3 inhibition, suggesting that Smad3 regulation of high glucose‐induced podocyte injury occurs through a p15^INK4B‐independent mechanism.

Conclusion

Smad3 signalling plays a critical role in the modulation of hyperglycaemic injury. Targeted inhibition of the Smad3 pathway may offer a novel route for treatment of podocyte damage, especially in cases of diabetic nephropathy.

Podocyte damage is characteristic of diabetic kidney disease. This study showed that inhibition of Smad‐3 signalling using the specific inhibitor SIS3 in vitro, could alleviate podocyte abnormalities induced by high glucose including actin cytoskeletal rearrangement and actviation of cell death pathways.