Activation of RhoA/ROCK regulates NF-κB signaling pathway in experimental diabetic nephropathy

Exosomes derived from mesenchymal stem cells in diabetes and diabetic complications

Diabetes, a group of metabolic disorders, constitutes an important global health problem. Diabetes and its complications place a heavy financial strain on both patients and the global healthcare establishment. The lack of effective treatments contributes to this pessimistic situation and negative outlook. Exosomes released from mesenchymal stromal cells (MSCs) have emerged as the most likely new breakthrough and advancement in treating of diabetes and diabetes-associated complication due to its capacity of intercellular communication, modulating the local microenvironment, and regulating cellular processes. In the present review, we briefly outlined the properties of MSCs-derived exosomes, provided a thorough summary of their biological functions and potential uses in diabetes and its related complications.

Design, Synthesis, and Biological Evaluation of an Orally Bioavailable, Potent, and Selective ROCK2 Inhibitor for Psoriasis Treatment

Psoriasis, a prevalent chronic skin disorder, remains a significant therapeutic obstacle. This study centers on rho-associated coiled-coil-containing kinase2 (ROCK2) as an advantageous target for treating psoriasis and identifies five potent and selective ROCK2 inhibitors (A31-35). Notably, A32-35 outperform KD025 in ROCK2/ROCK1 selectivity by up to 216-fold. Among these candidates, A31 emerged as an exceedingly promising molecule, showcasing remarkable inhibitory potency (IC50 = 3.7 ± 0.8 nM), 19-fold ROCK2/ROCK1 selectivity, and favorable pharmacokinetics. Insights from the binding mode study further underscored the pivotal role of interactions with Phe103 on the P-loop in determining the selectivity between ROCK1 and ROCK2. In an imiquimod-induced psoriasis-like mouse model, oral administration of A31 notably ameliorated symptoms by targeting the IL-23/Th17 axis. Based on these compelling findings, A31 was selected as a highly promising compound for further investigation as a potential treatment for psoriasis.

Anti-inflammatory effect and mechanism of catalpol in various inflammatory diseases

Catalpol is a kind of iridoid glucoside, widely found in a variety of plants, mostly extracted from the rhizome of the traditional medicinal herb rehmanniae. It has various biological activities such as anti-inflammatory, antioxidant, and antitumor. The anti-inflammatory effects of catalpol have been demonstrated in a variety of diseases, such as neurological diseases, atherosclerosis, renal diseases, respiratory diseases, digestive diseases, bone and joint diseases, eye diseases, and periodontitis. The purpose of this review is to summarize the existing literature on the anti-inflammatory effects of catalpol in a variety of inflammatory diseases over the last decade and to focus on the anti-inflammatory mechanisms of catalpol.

A proteoglycan isolated from Ganoderma lucidum attenuates diabetic kidney disease by inhibiting oxidative stress-induced renal fibrosis both in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (G. lucidum) was regarded as "miraculous herb" by the Chinese and recorded detailly in the "Shen Nong Ben Cao Jing" as a tonic to improve health and prolong life. A proteoglycan (namely, FYGL) was extracted from Ganoderma lucidum, which was a water-soluble hyperbranched proteoglycan, and was found to be able to protect pancreatic tissue against oxidative stress damage.

AIM OF THE STUDY

Diabetic kidney disease (DKD) is a complication of diabetes, but the effective treatment is still lack. Chronic hyperglycemia in diabetic patients induce the accumulation of ROS, which injure the renal tissue and lead to the renal dysfunction. In this work, the efficacy and target mechanics of FYGL on diabetic renal function were investigated.

MATERIALS AND METHODS

In the present study, the mechanism of the reno-protection of FYGL was analyzed on diabetic db/db mice and rat glomerular mesangial cells (HBZY-1) induced by high glucose (HG) with palmitate (PA) (HG/PA). In vitro, the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were evaluated by commercial kits. the expressions of NOX1 and NOX4, phosphorylation of MAPK and NF-κB, and pro-fibrotic proteins were measured by Western blot. In vivo, diabetic db/db mice were gavaged with FYGL for 8 weeks, body weight and fasting blood glucose (FBG) were tested weekly. On 8th week, the serum, urine and renal tissue were collected for glucose tolerance test (OGTT), redox indicator (SOD, CAT, GSH and MDA), lipid metabolism (TC, TG, LDL and HDL), blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA), 8-oxo-deoxyguanosine (8-OHdG), and the changes of histopathology and expression of collagen IV and AGEs.

RESULTS

The results in vitro showed that FYGL significantly inhibited the HG/PA-induced HBZY-1 cells proliferation, ROS generation, MDA production, promoted SOD activity, and suppressed NOX1, NOX4, MAPK, NF-κB, and pro-fibrotic proteins expression. In addition, FYGL markedly alleviated blood glucose, antioxidant activity and lipid metabolism, improved renal functions, and relieved renal histopathological abnormalities, especially renal fibrosis.

CONCLUSIONS

The antioxidant activity of FYGL can reduce ROS caused by diabetes and protect renal from oxidative stress-induced dysfunction, thereby improving renal function. This study shows that FYGL has the potential to treat diabetic kidney disease.

A natural products solution to diabetic nephropathy therapy

Diabetic nephropathy is one of the most common complications in diabetes. It has been shown to be the leading cause of end-stage renal disease. However, due to their complex pathological mechanisms, effective therapeutic drugs other than angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which have been used for 20 years, have not been developed so far. Recent studies have shown that diabetic nephropathy is characterized by multiple signalling pathways and multiple targets, including inflammation, apoptosis, pyroptosis, autophagy, oxidative stress, endoplasmic reticulum stress and their interactions. It definitely exacerbates the difficulty of therapy, but at the same time it also brings out the chance for natural products treatment. In the most recent two decades, a large number of natural products have displayed their potential in preclinical studies and a few compounds are under invetigation in clinical trials. Hence, many compounds targeting these singals have been emerged as a comprehensive blueprint for treating strategy of diabetic nephropathy. This review focuses on the cellular and molecular mechanisms of natural prouducts that alleviate this condition, including preclinical studies and clinical trials, which will provide new insights into the treatment of diabetic nephropathy and suggest novel ideas for new drug development.

Transcription Factor p300 Regulated miR-451b Weakens the Cigarette Smoke Extract-Induced Cellular Stress by Targeting RhoA/ROCK2 Signaling

Background

A previous study identified miR-451b as a potential biomarker in smoker with or without chronic obstructive pulmonary disease (COPD). However, the function and molecular mechanisms of miR-451b in the pathogenesis of COPD remain elusive.

Methods

Macrophages and lung fibroblasts were exposed to 10% cigarette smoke extract (CSE) solution for 24 h. Expression miR-451b and its potential transcription factor p300 were detected. The association between p300 and miR-451b, miR-451b and RhoA was validated by luciferase reporter assay. The release of IL-12 and TNF-αby macrophages was measured by ELISA assay, and Transwell assay was performed to analyze its migration and invasion. Collagen protein of fibroblasts was detected by Western blotting.

Results

Results showed that p300 and miR-451b was downregulated, while RhoA was upregulated in CSE-induced macrophages and lung fibroblasts. The stimulation of CSE promoted the degradation of p300 by ubiquitination, and RhoA was confirmed as the target gene of miR-451b. MiR-451b overexpression significantly decreased the release of IL-12 and TNF-α, downregulated the expression of RhoA, ROCK2, and p65, and suppressed cell migration and invasion in CES-induced macrophages. In addition, miR-451b overexpression decreased the expression of RhoA, ROCK2, COL1A1, and COL2A1 in lung fibroblasts.

Conclusions

Our data suggest that p300/miR-451b protects against CSE-induced cell stress possibly through downregulating RhoA/ROCK2 pathway.

NLRP3-mediated pyroptosis in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD), which is characterized by a series of abnormal changes such as glomerulosclerosis, podocyte loss, renal tubular atrophy and excessive deposition of extracellular matrix. Simultaneously, the occurrence of inflammatory reaction can promote the aggravation of DN-induced kidney injury. The most important processes in the canonical inflammasome pathway are inflammasome activation and membrane pore formation mediated by gasdermin family. Converging studies shows that pyroptosis can occur in renal intrinsic cells and participate in the development of DN, and its activation mechanism involves a variety of signaling pathways. Meanwhile, the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome can not only lead to the occurrence of inflammatory response, but also induce pyroptosis. In addition, a number of drugs targeting pyroptosis-associated proteins have been shown to have potential for treating DN. Consequently, the pathogenesis of pyroptosis and several possible activation pathways of NLRP3 inflammasome were reviewed, and the potential drugs used to treat pyroptosis in DN were summarized in this review. Although relevant studies are still not thorough and comprehensive, these findings still have certain reference value for the understanding, treatment and prognosis of DN.

Targeting the LPA1 signalling pathway for fibrosis therapy: a patent review (2010-present)

INTRODUCTION

Fibrosis is a disease that damages organs and even causes death. Because of the complicated pathogenesis, the development of drugs for fibrosis is challenging. In the lysophosphatidic acid receptor type 1 (LPA1) signalling pathway, LPA1 and its downstream Rho-associated coiled-coil forming protein kinase (ROCK) are related to the process of fibrosis. Targeting LPA1 signalling pathway is a potential strategy for the treatment of fibrosis.

AREA COVERED

This review describes the process of fibrosis mediated by the LPA1 signalling pathway and then summarizes LPA1 antagonist patents reported since 2010 and ROCK inhibitor patents since 2017 according to their scaffolds based on the Cortellis Drug Discovery Intelligence database. Information on LPA1 antagonists entering clinical trials is integrated.

EXPERT OPINION

Over the past decade, a large number of antagonists targeting the LPA1 signalling pathway have been patented for fibrosis therapy. A limited number of compounds have entered clinical trials. Different companies and research groups have used different scaffolds when designing compounds for fibrosis therapy. Therefore, LPA1 and ROCK are competitive targets for the development of new therapies for fibrosis to provide a potential treatment method for fibrosis in the future.

Network pharmacology study of Yishen capsules in the treatment of diabetic nephropathy

Objective

In this study, we used network pharmacology to explore the possible therapeutic mechanism underlying the treatment of diabetic nephropathy with Yishen capsules.

Methods

The active chemical constituents of Yishen capsules were acquired using the Traditional Chinese Medicine Systems Pharmacology platform and the Encyclopedia of Traditional Chinese Medicine. Component target proteins were then searched and screened in the BATMAN database. Target proteins were cross-validated using the Comparative Toxicogenomics Database, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the target proteins were performed. Then, protein–protein interaction (PPI) analysis was performed using the STRING database. Finally, a pharmacological network was constructed to show the component-target-pathway relationships. Molecular docking was used to analyse the interaction between drug components and target proteins.

Results

In total, 285 active chemical components were found, including 85 intersection targets against DN. In the pharmacological network, 5 key herbs (A. membranaceus, A. sinensis, E. ferox, A. orientale, and R. rosea) and their corresponding 12 key components (beta-sitosterol, beta-carotene, stigmasterol, alisol B, mairin, quercetin, caffeic acid, 1-monolinolein, kaempferol, jaranol, formononetin, and calycosin) were screened. Furthermore, the 12 key components were related to 24 target protein nodes (e.g., AGT, AKT1, AKT2, BCL2, NFKB1, and SIRT1) and enriched in 24 pathway nodes (such as the NF-kappa B, AGE-RAGE, toll-like receptor, and relaxin signaling pathways). Molecular docking revealed that hydrogen bond was formed between drug components and target proteins.

Conclusion

In conclusion, the active constituents of Yishen capsules modulate targets or signaling pathways in DN pathogenesis.

TNF-α Plus IL-1β Induces Opposite Regulation of Cx43 Hemichannels and Gap Junctions in Mesangial Cells through a RhoA/ROCK-Dependent Pathway

Connexin 43 (Cx43) is expressed in kidney tissue where it forms hemichannels and gap junction channels. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remains unknown. Here, analysis of ethidium uptake and thiobarbituric acid reactive species revealed that treatment with TNF-α plus IL-1β increases Cx43 hemichannel activity and oxidative stress in MES-13 cells (a cell line derived from mesangial cells), and in primary mesangial cells. The latter was also accompanied by a reduction in gap junctional communication, whereas Western blotting assays showed a progressive increase in phosphorylated MYPT (a target of RhoA/ROCK) and Cx43 upon TNF-α/IL-1β treatment. Additionally, inhibition of RhoA/ROCK strongly antagonized the TNF-α/IL-1β-induced activation of Cx43 hemichannels and reduction in gap junctional coupling. We propose that activation of Cx43 hemichannels and inhibition of cell-cell coupling during pro-inflammatory conditions could contribute to oxidative stress and damage of mesangial cells via the RhoA/ROCK pathway.

An insight into the potential of berberine in animal nutrition: Current knowledge and future perspectives

In animal nutrition, the interest for novel feed additives has expanded with elevating industry standards and consumer awareness besides the demand for healthy animal-derived food products. Consumer and animal health are leading concerns dictating the importance of novel animal feed additives. Berberine (BBR) is a natural pentacyclic isoquinoline alkaloid that has exhibited diverse pharmacological properties, including metabolism-regulating, hepatoprotective, and inflammatory alleviative in addition to its antioxidant activity. Despite detailed information on cellular mechanisms associated with BBR therapeutics, and strong clinical evidence, only a few studies have focused on BBR applied to animal nutrition. However, great pieces of evidence have shown that dietary BBR supplementation could result in improved growth performance, enhanced oxido-inflammatory markers, and mitigated metabolic dysfunctions in both monogastric and ruminant animals. The data discussed in the present review may set the basis for further research on BBR in animal diets for developing novel strategies aiming to improve animal health as well as products with beneficial properties for humans.

The Wnt Signaling Pathway in Diabetic Nephropathy

Diabetic nephropathy (DN) is a serious kidney-related complication of both type 1 and type 2 diabetes mellitus (T1DM, T2DM) and the second major cause of end-stage kidney disease. DN can lead to hypertension, edema, and proteinuria. In some cases, DN can even progress to kidney failure, a life-threatening condition. The precise etiology and pathogenesis of DN remain unknown, although multiple factors are believed to be involved. The main pathological manifestations of DN include mesangial expansion, thickening of the glomerular basement membrane, and podocyte injury. Eventually, these pathological manifestations will lead to glomerulosclerosis, thus affecting renal function. There is an urgent need to develop new strategies for the prevention and treatment of DN. Existing evidence shows that the Wnt signaling cascade plays a key role in regulating the development of DN. Previous studies focused on the role of the Wnt canonical signaling pathway in DN. Subsequently, accumulated evidence on the mechanism of the Wnt non-canonical signaling indicated that Wnt/Ca²⁺ and Wnt/PCP also have essential roles in the progression of DN. In this review, we summarize the specific mechanisms of Wnt signaling in the occurrence and development of DN in podocyte injury, mesangial cell injury, and renal fibrosis. Also, to elucidate the significance of the Wnt canonical pathway in the process of DN, we uncovered evidence supporting that both Wnt/PCP and Wnt/Ca²⁺ signaling are critical for DN development.

Rho GTPases in kidney physiology and diseases

Rho family GTPases are molecular switches best known for their pivotal role in dynamic regulation of the actin cytoskeleton, but also of cellular morphology, motility, adhesion and proliferation. The prototypic members of this family (RhoA, Rac1 and Cdc42) also contribute to the normal kidney function and play important roles in the structure and function of various kidney cells including tubular epithelial cells, mesangial cells and podocytes. The kidney's vital filtration function depends on the structural integrity of the glomerulus, the proximal portion of the nephron. Within the glomerulus, the architecturally actin-based cytoskeleton podocyte forms the final cellular barrier to filtration. The glomerulus appears as a highly dynamic signalling hub that is capable of integrating intracellular cues from its individual structural components. Dynamic regulation of the podocyte cytoskeleton is required for efficient barrier function of the kidney. As master regulators of actin cytoskeletal dynamics, Rho GTPases are therefore of critical importance for sustained kidney barrier function. Dysregulated activities of the Rho GTPases and of their effectors are implicated in the pathogenesis of both hereditary and idiopathic forms of kidney diseases. Diabetic nephropathy is a progressive kidney disease that is caused by injury to kidney glomeruli. High glucose activates RhoA/Rho-kinase in mesangial cells, leading to excessive extracellular matrix production (glomerulosclerosis). This RhoA/Rho-kinase pathway also seems involved in the post-transplant hypertension frequently observed during treatment with calcineurin inhibitors, whereas Rac1 activation was observed in post-transplant ischaemic acute kidney injury.

Caveolin-1 Regulates Cellular Metabolism: A Potential Therapeutic Target in Kidney Disease

The kidney is an energy-consuming organ, and cellular metabolism plays an indispensable role in kidney-related diseases. Caveolin-1 (Cav-1), a multifunctional membrane protein, is the main component of caveolae on the plasma membrane. Caveolae are represented by tiny invaginations that are abundant on the plasma membrane and that serve as a platform to regulate cellular endocytosis, stress responses, and signal transduction. However, caveolae have received increasing attention as a metabolic platform that mediates the endocytosis of albumin, cholesterol, and glucose, participates in cellular metabolic reprogramming and is involved in the progression of kidney disease. It is worth noting that caveolae mainly depend on Cav-1 to perform the abovementioned cellular functions. Furthermore, the mechanism by which Cav-1 regulates cellular metabolism and participates in the pathophysiology of kidney diseases has not been completely elucidated. In this review, we introduce the structure and function of Cav-1 and its functions in regulating cellular metabolism, autophagy, and oxidative stress, focusing on the relationship between Cav-1 in cellular metabolism and kidney disease; in addition, Cav-1 that serves as a potential therapeutic target for treatment of kidney disease is also described.

Fucoxanthin regulates Nrf2 signaling to decrease oxidative stress and improves renal fibrosis depending on Sirt1 in HG-induced GMCs and STZ-induced diabetic rats

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial cellular defense factor to cope with oxidative stress. Silent information regulator T1 (Sirt1) is a deacetylase with antioxidative stress activity. Fucoxanthin is a marine-derived carotenoid. This study was conducted to investigate whether fucoxanthin could alleviate oxidative stress by activating Sirt1/Nrf2 signaling to alleviate DN. In streptozotocin-induced diabetic rats, fucoxanthin treatment effectively improved renal function, alleviated glomerulosclerosis. Fucoxanthin reversed the decreased protein levels of Sirt1 and Nrf2 in the kidney of diabetic rats and glomerular mesangial cells cultured in high glucose. Conversely, EX527, a Sirt1 inhibitor, counteracted the effect of fucoxanthin on the expression of Nrf2. Furthermore, in vivo and vitro results showed that fucoxanthin treatment reversed the low expression and activity of superoxide dismutase and heme oxygenase 1, depending on Sirt1 activation. Our results suggest that fucoxanthin improves diabetic kidney function and renal fibrosis by activating Sirt1/Nrf2 signaling to reduce oxidative stress.

Ferulic acid attenuates non-alcoholic steatohepatitis by reducing oxidative stress and inflammation through inhibition of the ROCK/NF-κB signaling pathways

Ferulic acid (FA) is a natural polyphenol compound existing in many plants. The purpose of this study was to investigate the effect of FA on non-alcoholic steatohepatitis (NASH) induced by high-cholesterol and high-fat diet (HCHF) and its possible mechanism. Rats were fed HCHF for 12 weeks to establish NASH model. FA improved liver coefficients and had no effect on body weight changes. FA could reduce serum alanine transferase (ALT) and aspartate transferase (AST) activities. FA attenuated the increase of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein (LDL) levels caused by NASH, improved the liver pathological damage induced by NASH, and inhibited the progression of liver fibrosis. FA prevented the production of reactive oxygen species (ROS) and the increase of malondialdehyde (MDA) levels, and attenuated the decrease in superoxide dismutase (SOD) activity. Meanwhile, FA significantly restored the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α). In addition, we also found that FA inhibited the activity of ROCK and the activation of NF-κB signaling pathway in the liver of NASH rats. Overall, FA has a hepatoprotective anti-oxidative stress and anti-inflammatory effects in NASH rats, and its mechanism may be related to the inhibition of ROCK/NF-κB signaling pathway.

New progress in drugs treatment of diabetic kidney disease

Diabetic kidney disease (DKD) is not only one of the main complications of diabetes, but also the leading cause of the end-stage renal disease (ESRD). The occurrence and development of DKD have always been a serious clinical problem that leads to the increase of morbidity and mortality and the severe damage to the quality of life of human beings. Controlling blood glucose, blood pressure, blood lipids, and improving lifestyle can help slow the progress of DKD. In recent years, with the extensive research on the pathological mechanism and molecular mechanism of DKD, there are more and more new drugs based on this, such as new hypoglycemic drugs sodium-glucose cotransporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 (GLP-1) inhibitors, and dipeptidyl peptidase-4 (DPP-4) inhibitors with good efficacy in clinical treatment. Besides, there are some newly developed drugs, including protein kinase C (PKC) inhibitors, advanced glycation end product (AGE) inhibitors, aldosterone receptor inhibitors, endothelin receptor (ETR) inhibitors, transforming growth factor-β (TGF-β) inhibitors, Rho kinase (ROCK) inhibitors and so on, which show positive effects in animal or clinical trials and bring hope for the treatment of DKD. In this review, we sort out the progress in the treatment of DKD in recent years, the research status of some emerging drugs, and the potential drugs for the treatment of DKD in the future, hoping to provide some directions for clinical treatment of DKD.

Fasudil alleviated insulin resistance through promotion of proliferation, attenuation of cell apoptosis and inflammation and regulation of RhoA/Rho kinase/insulin/nuclear factor-κB signalling pathway in HTR-8/SVneo cells

OBJECTIVES

The aim of this study was to evaluate the effects of fasudil on insulin resistance (IR) in HTR-8/SVneo cells.

METHODS

HTR-8/SVneo cells were treated with insulin or/and fasudil. Cell proliferation, apoptosis, inflammation and related signalling pathways were assessed.

KEY FINDINGS

Insulin treatment significantly enhanced the protein expressions of RhoA and Rho kinase (ROCK1 and ROCK2), but decreased glucose consumption. Administration of fasudil effectively promoted glucose uptake. Moreover, fasudil enhanced cell viability and the level of proliferating cell nuclear antigen (PCNA). Insulin-mediated cell apoptosis was inhibited by fasudil via the down-regulation of bax and cleaved-caspase-3, and the up-regulation of bcl-2. At the same time, fasudil led to the reduction of IL-1β, TNF-α, IL-6 and IL-8 mRNA levels in insulin-treated cells. In addition, RhoA, ROCK2 and phosphorylated myosin phosphatase target subunit-1 (p-MYPT-1) expressions were down-regulated by fasudil. Importantly, fasudil activated insulin receptor substrate-1 (IRS-1) through increasing p-IRS-1 (Tyr612) and p-Akt expressions. The nuclear NF-κB p65 and p-IκB-α levels were reduced via the administration of fasudil in insulin-treated cells.

CONCLUSIONS

Fasudil mitigated IR by the promotion of cell proliferation, inhibition of apoptosis and inflammation and regulation of RhoA/ROCK/insulin/NF-κB signalling pathway through in vitro studies.

Islet Transplantation Reverses Podocyte Injury in Diabetic Nephropathy or Induced by High Glucose via Inhibiting RhoA/ROCK/NF-κB Signaling Pathway

OBJECTIVE

Abnormal signaling pathways play a crucial role in the mechanisms of podocyte injury in diabetic nephropathy. They also affect the recovery of podocytes after islet transplantation (IT). However, the specific signaling abnormalities that affect the therapeutic effect of IT on podocytes remains unclear. The purpose of this study was to assess whether the RhoA/ROCK/NF-κB signaling pathway is related to podocyte restoration after IT.

METHODS

A mouse model of diabetic nephropathy was established in vivo using streptozotocin. The mice were then subsequently reared for 4 weeks after islet transplantation to determine the effect of IT. Islet cells, CCG-1423 (RhoA Inhibitor), and fasudil (ROCK inhibitor) were then cocultured with podocytes in vitro to assess their protective effects on podocyte injury induced by high glucose (HG). Protein expression levels of RhoA, ROCK1, synaptopodin, IL-6, and MCP-1 in kidney tissues were then measured using immunohistochemistry and Western blotting techniques.

RESULTS

Islet transplantation reduced the expression levels of RhoA/ROCK1 and that of related inflammatory factors such as IL-6 and MCP-1 in the kidney podocytes of diabetic nephropathy. In the same line, islet cells reduced the expression of RhoA, ROCK1, and pp65 in immortalized podocytes under high glucose (35.0 mmol/L glucose) conditions.

CONCLUSIONS

Islet transplantation can reverse podocyte injury in diabetes nephropathy by inhibiting the RhoA/ROCK1 signaling pathway. Islet cells have a strong protective effect on podocytes treated with high glucose (35.0 mmol/L glucose). Discovery of signaling pathways affecting podocyte recovery is helpful for individualized efficacy evaluation and targeted therapy of islet transplantation patients.

YiQiFuMai Lyophilized Injection ameliorates tPA-induced hemorrhagic transformation by inhibiting cytoskeletal rearrangement associated with ROCK1 and NF-κB signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Thrombolytic therapy with tissue plasminogen activator (tPA) after ischemic stroke exacerbates blood-brain barrier (BBB) breakdown and leads to hemorrhagic transformation (HT). YiQiFuMai Lyophilized Injection (YQFM) is a modern preparation derived from Sheng-mai San (a traditional Chinese medicine). YQFM attenuates the BBB dysfunction induced by cerebral ischemia-reperfusion injury. However, whether YQFM can suppress tPA-induced HT remains unknown.

AIM OF THE STUDY

We investigated the therapeutic effect of YQFM on tPA-induced HT and explored the underlying mechanisms in vivo and in vitro to improve the safety of tPA use against stroke.

METHODS

Male C57BL/6J mice were subjected to 45 min of ischemia and 24 h of reperfusion. tPA (10 mg/kg) were infused 2 h after occlusion and YQFM (0.671 g/kg) was injected 2.5 h after occlusion. The in vitro effect of YQFM (100, 200, 400 μg/mL) on tPA (60 μg/mL)-induced dysfunction of the microvascular endothelial barrier in the brain following oxygen-glucose deprivation/reoxygenation (OGD/R) was observed in bEnd.3 cells.

RESULTS

YQFM suppressed tPA-induced high hemoglobin level in the brain, mortality, neurologic severity score, BBB permeability, expression and activation of matrix metalloproteinase (MMP)-9 and MMP-2, and degradation of tight-junction proteins. Furthermore, YQFM significantly blocked tPA-induced brain microvascular endothelial permeability and phosphorylation of Rho-associated kinase (ROCK)1, myosin light chain (MLC), cofilin and p65 in vivo and in vitro.

CONCLUSION

YQFM suppressed tPA-induced HT by inhibiting cytoskeletal rearrangement linked with ROCK-cofilin/MLC pathways and inhibiting the nuclear factor-kappa B pathway to ameliorate BBB damage caused by tPA.

YAP Activation in Renal Proximal Tubule Cells Drives Diabetic Renal Interstitial Fibrogenesis

An increasing number of studies suggest that the renal proximal tubule is a site of injury in diabetic nephropathy (DN), and progressive renal tubulointerstitial fibrosis is an important mediator of progressive kidney dysfunction in DN. In this study, we observed increased expression and activation of YAP (yes-associated protein) in renal proximal tubule epithelial cells (RPTC) in patients with diabetes and in mouse kidneys. Inducible deletion of Yap specifically in RPTC or administration of the YAP inhibitor verteporfin significantly attenuated diabetic tubulointerstitial fibrosis. EGFR-dependent activation of RhoA/Rock and PI3K-Akt signals and their reciprocal interaction were upstream of proximal tubule YAP activation in diabetic kidneys. Production and release of CTGF in culture medium were significantly augmented in human embryonic kidney (HEK)-293 cells transfected with a constitutively active YAP mutant, and the conditioned medium collected from these cells activated and transduced fibroblasts into myofibroblasts. This study demonstrates that proximal tubule YAP-dependent paracrine mechanisms play an important role in diabetic interstitial fibrogenesis; therefore, targeting Hippo signaling may be a therapeutic strategy to prevent the development and progression of diabetic interstitial fibrogenesis.

Identification of C3 as a therapeutic target for diabetic nephropathy by bioinformatics analysis

The pathogenesis of diabetic nephropathy is not completely understood, and the effects of existing treatments are not satisfactory. Various public platforms already contain extensive data for deeper bioinformatics analysis. From the GSE30529 dataset based on diabetic nephropathy tubular samples, we identified 345 genes through differential expression analysis and weighted gene coexpression correlation network analysis. GO annotations mainly included neutrophil activation, regulation of immune effector process, positive regulation of cytokine production and neutrophil-mediated immunity. KEGG pathways mostly included phagosome, complement and coagulation cascades, cell adhesion molecules and the AGE-RAGE signalling pathway in diabetic complications. Additional datasets were analysed to understand the mechanisms of differential gene expression from an epigenetic perspective. Differentially expressed miRNAs were obtained to construct a miRNA-mRNA network from the miRNA profiles in the GSE57674 dataset. The miR-1237-3p/SH2B3, miR-1238-5p/ZNF652 and miR-766-3p/TGFBI axes may be involved in diabetic nephropathy. The methylation levels of the 345 genes were also tested based on the gene methylation profiles of the GSE121820 dataset. The top 20 hub genes in the PPI network were discerned using the CytoHubba tool. Correlation analysis with GFR showed that SYK, CXCL1, LYN, VWF, ANXA1, C3, HLA-E, RHOA, SERPING1, EGF and KNG1 may be involved in diabetic nephropathy. Eight small molecule compounds were identified as potential therapeutic drugs using Connectivity Map.

Black mulberry fruit extract alleviates streptozotocin-induced diabetic nephropathy in rats: targeting TNF-α inflammatory pathway

OBJECTIVES

This study was designed to investigate the effect of Morus nigra fruit extract in retarding the progression of diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats.

METHODS

Diabetic male Wistar rats were injected with black mulberry fruit extract (BMFE) at doses of 150 and 300 mg/kg body weight. After 4 weeks, microalbuminuria was estimated in addition to serum concentrations of glucose, insulin, creatinine and albumin.

KEY FINDINGS

The study revealed a significant amelioration of all the measured parameters in diabetic animals. In addition, MDA, lipid peroxide levels and catalase activity were also improved. The histopathological examination of kidney tissues revealed significant improvement of the pathological changes and glomerular sclerosis in diabetic rats treated with BMFE. Treated rats showed downregulation of TNF-α, vascular cell adhesion molecule-1 (VCAM-1) and fibronectin mRNA expression.

CONCLUSION

The ameliorative effect of BMFE on diabetic nephropathy is not only through its potent antioxidant and hypoglycaemic effects but also through its downregulation of TNF-α, VCAM-1 and fibronectin mRNA expression in renal tissues of diabetic-treated rats. Therefore, BMFE as dietary supplement could be a promising agent in improving diabetic nephropathy.

Connexin-mediated cell communication in the kidney: A potential therapeutic target for future intervention of diabetic kidney disease?: Joan Mott Prize Lecture

The ability of cells to communicate and synchronise their activity is essential for the maintenance of tissue structure, integrity and function. A family of membrane-bound proteins called connexins are largely responsible for mediating the local transfer of information between cells. Assembled in the cell membrane as a hexameric connexon, they either function as a conduit for paracrine signalling, forming a transmembrane hemi-channel, or, if aligned with connexons on neighbouring cells, form a continuous aqueous pore or gap junction, which allows for the direct transmission of metabolic and electrical signals. Regulation of connexin synthesis and activity is critical to cellular function, and a number of diseases are attributed to changes in the expression and/or function of these important proteins. A link between hyperglycaemia, connexin expression, altered nucleotide concentrations and impaired function highlights a potential role for connexin-mediated cell communication in complications of diabetes. In the diabetic kidney, glycaemic injury is the leading cause of end-stage renal failure, reflecting multiple aetiologies including glomerular hyperfiltration, albuminuria, increased deposition of extracellular matrix and tubulointerstitial fibrosis. Loss of connexin-mediated cell-to-cell communication in diabetic nephropathy may represent an early sign of disease progression, but our understanding of the process remains severely limited. This review focuses on recent evidence demonstrating that glucose-evoked changes in connexin-mediated cell communication and associated purinergic signalling may contribute to the pathogenesis of kidney disease in diabetes, highlighting the tantalising potential of targeting these proteins as a novel therapeutic intervention.

Attenuation of Diabetic Nephropathy in Diabetic Mice by Fasudil through Regulation of Macrophage Polarization

Inflammation and fibrosis induced by hyperglycemia are considered to play a critical role in the pathogenesis of diabetic nephropathy. As macrophage polarization may determine the severity and progression of inflammation, regulation of macrophage polarization may be an effective method to treat diabetic complications. Fasudil, a potent Rho-kinase inhibitor, reportedly exhibits anti-inflammatory activity. However, whether fasudil reduces hyperglycemia-induced diabetic nephropathy via regulation of macrophage polarization remains unclear. In this study, we investigate the effect of fasudil on diabetic nephropathy in streptozotocin-induced type 1 diabetic mice. Our data showed that fasudil significantly decreased urinary protein and serum creatinine in diabetic mice, whereas it had no effect on the body weight and blood glucose. We also found increased M1-type macrophages and related proinflammatory cytokines, adverse fibrosis in renal tissue of diabetic mice. Interestingly, treatment of diabetic mice with fasudil increased the number of M2-type macrophages and related anti-inflammatory cytokines, which attenuated renal injury in diabetic mice. Taken together, the results of this study suggest that fasudil could slow the progression of diabetic nephropathy. The possible mechanism might be associated with its induction of M2 macrophage polarization and the reduction of M1 macrophage polarization and inflammation.

Mouse Umbilical Cord Mesenchymal Stem Cell Paracrine Alleviates Renal Fibrosis in Diabetic Nephropathy by Reducing Myofibroblast Transdifferentiation and Cell Proliferation and Upregulating MMPs in Mesangial Cells

Transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) is currently considered a novel therapeutic strategy for diabetic nephropathy (DN). However, the mechanisms by which UC-MSCs ameliorate renal fibrosis in DN are not well understood. Herein, we firstly investigated the therapeutic effects of mouse UC-MSC infusion on kidney structural and functional impairment in streptozotocin- (STZ-) induced diabetic mice. We found that the repeated injection with mUC-MSCs alleviates albuminuria, glomerulus injury, and fibrosis in DN mouse models. Next, mesangial cells were exposed to 5.6 mM glucose, 30 mM glucose, or mUC-MSC-conditioned medium, and then we performed western blotting, immunofluorescence, wound healing assay, and cell proliferation assay to measure extracellular matrix (ECM) proteins and matrix metalloproteinases (MMPs), myofibroblast transdifferentiation (MFT), and cell proliferation. We demonstrated that mUC-MSC paracrine decreased the deposition of fibronectin and collagen I by inhibiting TGF-β1-triggered MFT and cell proliferation mediated by PI3K/Akt and MAPK signaling pathways, and elevating the levels of MMP2 and MMP9. Importantly, we provided evidence that the antifibrosis role of mUC-MSC paracrine in DN might be determined by exosomes shed by MSCs. Together, these findings reveal the mechanisms underlying the therapeutic effects of UC-MSCs on renal fibrosis in DN and provide the evidence for DN cell-free therapy based on UC-MSCs in the future.

Knockdown of lncRNA PVT1 alleviates high glucose-induced proliferation and fibrosis in human mesangial cells by miR-23b-3p/WT1 axis

BACKGROUND

Diabetic nephropathy (DN) is a severe complication of diabetes with type 1 and 2. Long non-coding RNAs (lncRNAs) are being found to be involved in the DN pathogenesis. In this study, we aimed to further explore the effect and underlying mechanism of plasmacytoma variant translocation 1 (PVT1) in DN pathogenesis.

METHODS

The expression levels of PVT1, miR-23b-3p, and Wilms tumor protein 1 (WT1) mRNA were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot analysis was performed to determine protein expression. Cell proliferation was detected using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetr-azolium (MTS) assay. The targeted correlation between miR-23b-3p and PVT1 or WT1 was verified by dual-luciferase reporter assay.

RESULTS

PVT1 and WT1 were highly expressed in the serum of DN patients and high glucose (HG)-induced mesangial cells (MCs). The knockdown of PVT1 or WT1 ameliorated HG-induced proliferation and fibrosis in MCs. Mechanistically, PVT1 modulated WT1 expression through acting as a molecular sponge of miR-23b-3p. The miR-23b-3p/WT1 axis mediated the protective effect of PVT1 knockdown on HG-induced proliferation and fibrosis in MCs. The NF-κB pathway was involved in the regulatory network of the PVT1/miR-23b-3p/WT1 axis in HG-induced MCs.

CONCLUSION

Our study suggested that PVT1 knockdown ameliorated HG-induced proliferation and fibrosis in MCs at least partially by regulating the miR-23b-3p/WT1/NF-κB pathway. Targeting PVT1 might be a potential therapeutic strategy for DN treatment.

Fucoxanthin Alleviates Oxidative Stress through Akt/Sirt1/FoxO3α Signaling to Inhibit HG-Induced Renal Fibrosis in GMCs

As one of the main marine carotenoids, fucoxanthin has strong antioxidant activity. FoxO3α, a member of the forkhead box O family of transcription factors, plays an important role in DN by regulating oxidative stress. The activity of FoxO3α is related to its phosphorylation and acetylation status, regulated by Akt and Sirt1, a lysine deacetylase. Our study aimed to investigate whether fucoxanthin could alleviate oxidative stress and fibrosis via FoxO3α in DN and whether Akt and Sirt1 were involved. We found that in GMCs cultured in HG, fucoxanthin treatment significantly reduced the expression of FN and collagen IV, as well as reactive oxygen species generation, suggesting that fucoxanthin is beneficial to alleviate both fibrosis and oxidative stress in DN. In addition, we found that fucoxanthin decreased the phosphorylation and acetylation level of FoxO3α, reversed the protein level of FoxO3α inhibited by HG, and then promoted the nuclear transport of FoxO3α. Besides, fucoxanthin promoted the expression of manganese superoxide dismutase, a downstream target of FoxO3α. Furthermore, we found that fucoxanthin reversed the activation of Akt and inhibition of Sirt1. However, the enhancement of fucoxanthin in FoxO3α expression and nuclear transport was significantly decreased by pretreatment with Akt activator SC79 or Sirt1 inhibitor EX527. In summary, our study explored fucoxanthin alleviated oxidative stress and fibrosis induced by HG through Akt/Sirt1/FoxO3α signaling in GMCs, suggesting fucoxanthin is a potential therapeutic strategy for DN.

Differential coexpression networks in bronchiolitis and emphysema phenotypes reveal heterogeneous mechanisms of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease with multiple molecular mechanisms. To investigate and contrast the molecular processes differing between bronchiolitis and emphysema phenotypes of COPD, we downloaded the GSE69818 microarray data set from the Gene Expression Omnibus (GEO), which based on lung tissues from 38 patients with emphysema and 32 patients with bronchiolitis. Then, weighted gene coexpression network analysis (WGCNA) and differential coexpression (DiffCoEx) analysis were performed, followed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analysis (KEGG) analysis. Modules and hub genes for bronchiolitis and emphysema were identified, and we found that genes in modules linked to neutrophil degranulation, Rho protein signal transduction and B cell receptor signalling were coexpressed in emphysema. DiffCoEx analysis showed that four hub genes (IFT88, CCDC103, MMP10 and Bik) were consistently expressed in emphysema patients; these hub genes were enriched, respectively, for functions of cilium assembly and movement, proteolysis and apoptotic mitochondrial changes. In our re‐analysis of GSE69818, gene expression networks in relation to emphysema deepen insights into the molecular mechanism of COPD and also identify some promising therapeutic targets.

ROCK2 regulates TGF-β-induced expression of CTGF and profibrotic genes via NF-κB and cytoskeleton dynamics in mesangial cells

The small GTPase Rho and its effector Rho kinase (ROCK) are involved in the pathogenesis of diabetic kidney disease. Rho kinase has two isoforms: ROCK1 and ROCK2. However, it remains unclear which is mainly involved in the progression of diabetic glomerulosclerosis and the regulation of profibrotic mediators. Glomeruli isolated from type 2 diabetic db/db mice demonstrated increased gene expression of transforming growth factor (TGF)-β and its downstream profibrotic mediators. Chemical inhibition of ROCK suppressed the expression of profibrotic mediators in both isolated glomeruli and cultured mesangial cells. An investigation of mechanisms underlying this observation revealed activated ROCK functions through the phosphorylation of JNK and Erk and the nuclear translocation of NF-κB via actin dynamics. Knockdown by siRNA against ROCK1 and ROCK2 showed that ROCK2 but not ROCK1 controls this fibrotic machinery. Further in vivo experiments showed that ROCK2 activity in the renal cortex of db/db mice was elevated compared with control db/m mice. Importantly, oral administration of ROCK2 inhibitor attenuated renal ROCK2 activity, albuminuria, and glomerular fibrosis in db/db mice. These observations indicate that ROCK2 is a key player in the development of diabetic renal injury. Glomerular ROCK2 may be a potential therapeutic target for the treatment of diabetic kidney disease.

Ganoderic acid A attenuates lipopolysaccharide-induced lung injury in mice

The present study aimed to investigate the protective effects of ganoderic acid A (GAA) on lipopolysaccharide (LPS)-induced acute lung injury. In mouse model of LPS-induced acute lung injury, we found that GAA led to significantly lower lung wet-to-dry weight ratio and lung myeloperoxidase activity, and attenuated pathological damages. In addition, GAA increased superoxide dismutase activity, but decreased malondialdehyde content and proinflammatory cytokines levels in the bronchoalveolar lavage fluid. Mechanistically, GAA reduced the activation of Rho/ROCK/NF-κB pathway to inhibit LPS-induced inflammation. In conclusion, our study suggests that GAA attenuates acute lung injury in mouse model via the inhibition of Rho/ROCK/NF-κB pathway.

EphA2 antagonism alleviates LPS-induced acute lung injury via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways

Eph receptor tyrosine kinases have a wide range of biological functions and have gradually been recognized increasingly as key regulators of inflammation and injury diseases. Although previous studies suggested that EphA2 receptor may be involved in the regulation of inflammation and vascular permeability in injured lung, the detailed effects of EphA2 on LPS-induced acute lung injury (ALI) are still inadequate and the underlying mechanism remains poorly understood. In this study, we detected the effects of EphA2 antagonism on inflammation, pulmonary vascular permeability and oxidative stress in LPS-induced ALI and investigate the potential mechanism. Our results showed that EphA2 antagonism markedly inhibited the cytokines release and inflammatory cells infiltration in BALF, prevented the LPS-induced elevations of MPO activity and MDA level in lung tissues. Our study also found that EphA2 antagonism significantly decreased the wet/dry ratios, reduced the Evans blue albumin extravasation in lung tissues and obviously alleviated the LPS-induced increment of pulmonary vascular permeability. Mechanistically, EphA2 antagonism significantly increased the activation of Nrf2 along with its target antioxidant enzyme HO-1 and inhibited the expressions of TLR4/MyD88 in lung tissues and A549 alveolar epithelial cells. Furthermore, EphA2 antagonism dramatically inhibited the LPS-evoked activations of RhoA/ROCK in lung tissues. In conclusion, our data indicate that EphA2 receptor plays an essential role in LPS-induced ALI and EphA2 antagonism has protective effects against LPS-induced ALI via Nrf2/HO-1, TLR4/MyD88 and RhoA/ROCK pathways. These results suggest that antagonism of EphA2 may be an effective therapeutic strategy for the treatment of ALI.

Increased Extracellular Matrix Protein Production in Chronic Diabetic Complications: Implications of Non-Coding RNAs

Management of chronic diabetic complications remains a major medical challenge worldwide. One of the characteristic features of all chronic diabetic complications is augmented production of extracellular matrix (ECM) proteins. Such ECM proteins are deposited in all tissues affected by chronic complications, ultimately causing organ damage and dysfunction. A contributing factor to this pathogenetic process is glucose-induced endothelial damage, which involves phenotypic transformation of endothelial cells (ECs). This phenotypic transition of ECs, from a quiescent state to an activated dysfunctional state, can be mediated through alterations in the synthesis of cellular proteins. In this review, we discussed the roles of non-coding RNAs, specifically microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), in such processes. We further outlined other epigenetic mechanisms regulating the biogenesis and/or function of non-coding RNAs. Overall, we believe that better understanding of such molecular processes may lead to the development of novel biomarkers and therapeutic strategies in the future.

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.

Fisetin supplementation prevents high fat diet-induced diabetic nephropathy by repressing insulin resistance and RIP3-regulated inflammation

Obesity-related renal disease is related to caloric excess promoting deleterious cellular responses.

Astaxanthin ameliorates experimental diabetes-induced renal oxidative stress and fibronectin by upregulating connexin43 in glomerular mesangial cells and diabetic mice

Oxidative stress is the major cause of renal fibrosis in the progression of DN. Connexin43 (Cx43) exerts an anti-fibrosis effect on diabetic kidneys. The current study aimed to investigate whether astaxanthin (AST) could ameliorate the pathological progression of DN by upregulating Cx43 and activating the Nrf2/ARE signaling, which is a pivotal anti-oxidative stress system, to strengthen the cellular anti-oxidative capacity and diminish fibronectin (FN) accumulation in HG-induced glomerular mesangial cells (GMCs). Our hypothesis was verified in GMCs and the kidneys from db/db mice by western blot, immunofluorescence, immunohistochemistry, immunoprecipitation, dual luciferase reporter assay and reactive oxygen related detection kits. Results showed that AST simultaneously upregulated the Cx43 protein level and promoted the Nrf2/ARE signaling activity in the kidney of db/db mice and HG-treated GMCs. However, Cx43 depletion abrogated the Nrf2/ARE signaling activation induced by AST. AST reduced the interaction between c-Src and Nrf2 in the nuclei of GMCs cultured with HG, thereby enhancing the Nrf2 accumulation in the nuclei of GMCs. Our data suggested that AST promoted the Nrf2/ARE signaling by upregulating the Cx43 protein level to prevent renal fibrosis triggered by HG in GMCs and db/db mice. c-Src acted as a mediator in these processes.

The Pathogenesis of Diabetes Mellitus by Oxidative Stress and Inflammation: Its Inhibition by Berberine

A substantial knowledge on the pathogenesis of diabetes mellitus (DM) by oxidative stress and inflammation is available. Berberine is a biologically active botanical that can combat oxidative stress and inflammation and thus ameliorate DM, especially type 2 DM. This article describes the potential of berberine against oxidative stress and inflammation with special emphasis on its mechanistic aspects. In diabetic animal studies, the modified levels of proinflammatory cytokines and oxidative stress markers were observed after administering berberine. In renal, fat, hepatic, pancreatic and several others tissues, berberine-mediated suppression of oxidative stress and inflammation was noted. Berberine acted against oxidative stress and inflammation through a very complex mechanism consisting of several kinases and signaling pathways involving various factors, including NF-κB (nuclear factor-κB) and AMPK (AMP-activated protein kinases). Moreover, MAPKs (mitogen-activated protein kinases) and Nrf2 (nuclear factor erythroid-2 related factor 2) also have mechanistic involvement in oxidative stress and inflammation. In spite of above advancements, the mechanistic aspects of the inhibitory role of berberine against oxidative stress and inflammation in diabetes mellitus still necessitate additional molecular studies. These studies will be useful to examine the new prospects of natural moieties against DM.

Rapeseed protein-derived antioxidant peptide RAP alleviates renal fibrosis through MAPK/NF-κB signaling pathways in diabetic nephropathy

Introduction

Kidney fibrosis is the main pathologic change in diabetic nephropathy (DN), which is the major cause of end-stage renal disease. Current therapeutic strategies slow down but cannot reverse the progression of renal dysfunction in DN. Plant-derived bioactive peptides in foodstuffs are widely used in many fields because of their potential pharmaceutical and nutraceutical benefits. However, this type of peptide has not yet been studied in renal fibrosis of DN. Previous studies have indicated that the peptide YWDHNNPQIR (named RAP), a natural peptide derived from rapeseed protein, has an antioxidative stress effect. The oxidative stress is believed to be associated with DN. The aim of this study was to evaluate the pharmacologic effects of RAP against renal fibrosis of DN and high glucose (HG)-induced mesangial dysfunction.

Materials and methods

Diabetes was induced by streptozotocin and high-fat diet in C57BL/6 mice and these mice were treated by subcutaneous injection of different doses of RAP (0.1 mg/kg and 0.5 mg/kg, every other day) or PBS for 12 weeks. Later, functional and histopathologic analyses were performed. Parallel experiments verifying the molecular mechanism by which RAP alleviates DN were carried out in HG-induced mesangial cells (MCs).

Results

RAP improved the renal function indices, including 24-h albuminuria, triglyceride, serum creatinine, and blood urea nitrogen levels, but did not lower blood glucose levels in DN mice. RAP also simultaneously attenuated extracellular matrix accumulation in DN mice and HG-induced MCs. Furthermore, RAP reduced HG-induced cell proliferation, but it showed no toxicity in MCs. Additionally, RAP inhibited the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways.

Conclusion

RAP can attenuate fibrosis in vivo and in vitro by antagonizing the MAPK and NF-κB pathways.

Astaxanthin Promotes Nrf2/ARE Signaling to Inhibit HG-Induced Renal Fibrosis in GMCs

Oxidative stress is the main cause of diabetic nephropathy (DN) progression. Nuclear factor-erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling is a crucial cellular defense system to cope with oxidative stress. Astaxanthin (AST) is a fat-soluble xanthophyll carotenoid with remarkable antioxidative capacity. AST exerted renal protective in diabetic rats. This study aimed to determine whether AST could alleviate the pathological progress of DN by activating Nrf2/ARE signaling and diminishing the excessive oxidative stress and fibronectin (FN) accumulation in glomerular mesangial cells (GMCs) challenged with high glucose (HG). In the current study, we found that AST treatment alleviated the metabolic parameters, renal morphology and extracellular matrix (ECM) accumulation in streptozotocin-induced diabetic rats. Additionally, HG induced the adaptively activated Nrf2/ARE signaling and increased the expression of FN, intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-β1 (TGF-β1), as well as the intracellular reactive oxygen species (ROS) generation in GMCs. However, AST treatment strongly promoted the nuclear translocation and transcriptional activity of Nrf2 as well as upregulated the expression of superoxide dismutase (SOD1), NAD(P)H: quinone oxidoreductase (NQO1) and heme oxygenase-1 (HO-1), ultimately quenching the higher level of ROS and inhibiting the FN, ICAM-1 and TGF-β1 expression induced by HG. Collectively, our data suggest that the renoprotective effect of AST on DN depends on Nrf2/ARE signaling activation, which could be a potentially therapeutic strategy in the treatment of DN.

NFkB hyperactivation causes invasion of esophageal squamous cell carcinoma with EGFR overexpression and p120-catenin down-regulation

Four out of five patients diagnosed with esophageal squamous cell carcinoma (ESCC) will die within five years. This is primarily a result of the aggressive invasive potential of the disease. Our research is focused on the interplay between tumor suppressors and oncogenes in the invasive process. Specifically, EGFR and p120-catenin (p120ctn) are commonly dysregulated genes that are indicative of poor prognosis in ESCC. In a previous study we demonstrated that in our 3D organotypic culture model, only when EGFR overexpression is combined with p120ctn inactivation do the cells transform and invade – as opposed to either event alone. The purpose of this present study was to identify the components of the molecular pathways downstream of p120ctn and EGFR that lead to invasion. Using both human esophageal keratinocytes and human ESCC cells, we have identified NFkB as a central regulator of the invasive process downstream of p120ctn down-regulation and EGFR overexpression. Interestingly, we found that NFkB is hyperactivated in cells with EGFR overexpression and p120ctn inactivation than with either EGFR or p120ctn alone. Inhibition of this NFkB hyperactivation results in complete loss of invasion, suggesting that NFkB signaling is necessary for invasion in this aggressive cell type. Furthermore, we have identified RhoA and Rho-kinase as upstream regulators of NFkB in this process. We believe the cooperation of p120ctn down-regulation and EGFR overexpression is not only important in the aggressive mechanisms of ESCC but could be broadly applicable to many other cancer types in which p120ctn and EGFR are involved.

Bioactive phytochemicals that regulate the cellular processes involved in diabetic nephropathy

BACKGROUND

Owing to the multiple causative factors, the current advances in medication for diabetic nephropathy (DN) do not appear to have improved therapies for patients. Furthermore, use of multiple synthetic medications has shown various adverse effects and ultimately leads to deterioration of the condition. Medicinal plants and their bioactive constituents are considered to be safer and more effective than synthetic medicines against various chronic diseases. Therefore, the use of natural products in the management of DN has been suggested. In this article, we review medicinal plants and their specific bioactive phytochemicals that regulate the various cellular processes involved in the initiation of DN. A wide range of literature on phytochemicals and medicinal plants that may ameliorate DN was explored from the online available English works in various electronic databases, including Embase, Google Scholar, PubMed, Scopus, and Science Direct.

RESULTS

Medicinal plants possess various bioactive constituents, which may slow or ameliorate the progression of DN and improve renal function through the targeting of multiple pathological causes via different pathways, including p38MAPK, JNK, ERK, TGF-β, RhoA, NF-κB, Wnt, JAK-STAT, AMPK, mTOR, Akt, and TXNIP. Depletion or inhibition of these accelerating factors may provide a significant treatment for DN.

CONCLUSION

Based on various experimental studies, traditional herbs and their bioactive constituents regulate the cellular processes involved in the initiation of DN owing to their significant pharmacological activities; however, the efficacy in animal models and humans has not yet been explored. Therefore, studies should be performed to evaluate the nephroprotective effects of medicinal plants in preclinical animal models and in humans.

Astaxanthin Promotes Nrf2/ARE Signaling to Alleviate Renal Fibronectin and Collagen IV Accumulation in Diabetic Rats

Astaxanthin (AST), a natural keto-carotenoid classified as a xanthophyll, is well known for its antioxidant properties. AST can ameliorate the pathological characteristics of diabetic nephropathy (DN). However, the underlying mechanisms remain to be explored. This study was aimed at exploring whether AST exerts a protective effect on DN via activating nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidative response element (ARE) signaling. Streptozotocin-induced diabetic rats were treated with AST for 12 weeks. We found that AST treatment ameliorated renal morphological injury. Reduced fibronectin and collagen IV protein expression were found in the kidneys of diabetic rats. Furthermore, AST promoted the nuclear translocation of Nrf2 and increased its downstream protein heme oxygenase-1 and superoxide dismutase 1 expression. AST also increased the activity of SOD and decreased malondialdehyde generation in the serum of diabetic rats. These results suggest that the renoprotective effect of AST on DN partly depends on Nrf2-ARE signaling. The antioxidative stress effect of AST is responsible for the activation of Nrf2-ARE signaling in DN.

Sphingosine kinase 1 mediates diabetic renal fibrosis via NF-κB signaling pathway: involvement of CK2α

Sphingosine kinase 1 (SphK1) plays a pivotal role in regulating diabetic renal fibrotic factors such as fibronectin (FN) and intercellular adhesion molecule-1 (ICAM-1). Especially, activation of SphK1 is closely linked to the body inflammatory reaction. Casein kinase 2α subunit (CK2α), a protein kinase related to inflammatory reaction, influences diabetic renal fibrosis and expressions of FN and ICAM-1 via NF-κB pathway. However, the mechanism by which SphK1 mediates diabetic renal fibrosis has not yet fully elucidated. The current study is aimed to investigate if SphK1 mediates diabetic renal fibrotic pathological process via inflammatory pathway and activation of CK2α. The following findings were observed: (1) Expressions of SphK1 were upregulated in kidneys of diabetic mice and rats; (2) Knockdown of SphK1 expression suppressed high glucose (HG)-induced NF-κB nuclear translocation and expressions of FN and ICAM-1; (3) Compared with C57 diabetic mice, SphK1-/- diabetic mice exhibited less renal fibrotic lesions, FN accumulation and NF-κB nuclear accumulation in glomeruli of kidneys; (4) SphK1 mediated phosphorylation of CK2α, while CK2α knockdown depressed SphK1-induced activation of NF-κB pathway. This study indicates the essential role of SphK1 in regulating activation of CK2α and diabetic renal fibrotic pathological process via NF-κB.

Src family kinases in chronic kidney disease

Src family kinases (SFKs) belong to nonreceptor protein tyrosine kinases and have been implicated in the regulation of numerous cellular processes, including cell proliferation, differentiation, migration and invasion, and angiogenesis. The role and mechanisms of SFKs in tumorgenesis have been extensively investigated, and some SFK inhibitors are currently under clinical trials for tumor treatment. Recent studies have also demonstrated the importance of SFKs in regulating the development of various fibrosis-related chronic diseases (e.g., idiopathic pulmonary fibrosis, liver fibrosis, renal fibrosis, and systemic sclerosis). In this article, we summarize the roles of SFKs in various chronic kidney diseases, including glomerulonephritis, diabetic nephropathy, human immunodeficiency virus-associated nephropathy, autosomal dominant form of polycystic kidney disease, and obesity-associated kidney disease, and discuss the mechanisms involved.

Andrographolide ameliorates diabetic nephropathy by attenuating hyperglycemia-mediated renal oxidative stress and inflammation via Akt/NF-κB pathway

Diabetic nephropathy (DN) is characterized by proliferation of mesangial cells, mesangial hypertrophy and extracellular matrix (ECM) accumulation. Our recent study found that andrographolide inhibited high glucose-induced mesangial cell proliferation and fibronectin expression through inhibition of AP-1 pathway. However, whether andrographolide has reno-protective roles in DN has not been fully elucidated. Here, we studied the pharmacological effects of andrographolide against the progression of DN and high glucose-induced mesangial dysfunction. Diabetes was induced in C57BL/6 mice by intraperitoneal injection of streptozotocin (STZ). After 1 weeks after STZ injection, normal diet was substituted with a high-fat diet (HFD). Diabetic mice were intraperitoneal injected with andrographolide (2 mg/kg, twice a week). After 8 weeks, functional and histological analyses were carried out. Parallel experiments uncovering the molecular mechanism by which andrographolide prevents from DN was performed in mesangial cells. Andrographolide inhibited the increases in fasting blood glucose, triglyceride, kidney/body weight ratio, blood urea nitrogen, serum creatinine and 24-h albuminuria in diabetic mice. Andrographolide also prevented renal hypertrophy and ECM accumulation. Furthermore, andrographolide markedly attenuated NOX1 expression, ROS production and pro-inflammatory cytokines as well. Additionally, andrographolide inhibited Akt/NF-κB signaling pathway. These results demonstrate that andrographolide is protective against the progression of experimental DN by inhibiting renal oxidative stress, inflammation and fibrosis.

TGR5 suppresses high glucose-induced upregulation of fibronectin and transforming growth factor-β1 in rat glomerular mesangial cells by inhibiting RhoA/ROCK signaling

RhoA/ROCK can cause renal inflammation and fibrosis in the context of diabetes by activating nuclear factor-κB (NF-κB). TGR5 is known for its role in maintaining metabolic homeostasis and anti-inflammation, which is closely related to NF-κB inhibition. Given that TGR5 is highly enriched in kidney, we aim to investigate the regulatory role of TGR5 on fibronectin (FN) and transforming growth factor-β1 (TGF-β1) in high glucose (HG)-treated rat glomerular mesangial cells (GMCs). Both the factors are closely related to renal inflammations and mediated by NF-κB. Moreover, our study determines whether such regulation is achieved by the inhibition of RhoA/ROCK and the subsequent NF-κB suppression. Polymerase chain reaction was taken to test the mRNA level of TGR5. Western blot was used to measure the protein expressions of TGR5, FN, TGF-β1, p65, IκBα, phospho-MYPT1 (Thr853), and MYPT1. Glutathione S-transferase-pull down and immunofluorescence were conducted to test the activation of RhoA, the distribution of TGR5, and p65, respectively. Electrophoretic mobility shift assay was adopted to measure the DNA binding activity of NF-κB. In GMCs, TGR5 activation or overexpression significantly suppressed FN and TGF-β1 protein expressions, NF-κB, and RhoA/ROCK activation induced by HG or transfection of constitutively active RhoA. By contrast, TGR5 RNA interference caused enhancement of FN, TGF-β1 protein expressions, increase of RhoA/ROCK activation. However, TGR5 cannot suppress RhoA/ROCK activation when a selective Protein kinase A (PKA) inhibitor was used. This study suggests that in HG-treated GMCs, TGR5 significantly suppresses the NF-κB-mediated upregulation of FN and TGF-β1, which are hallmarks of diabetic nephropathy. These functions are closely related to the suppression of RhoA/ROCK via PKA.

Protodioscin ameliorates fructose-induced renal injury via inhibition of the mitogen activated protein kinase pathway

BACKGROUND

High dietary fructose can cause metabolic syndrome and renal injury.

PURPOSE

The effects of protodioscin on metabolic syndrome and renal injury were investigated in mice receiving high-dose fructose.

METHODS

Mice received 30% (w/v) fructose in water and standard chow for 6 weeks to induce metabolic syndrome and were divided into four groups to receive carboxymethylcellulose sodium, allopurinol (5 mg/kg) and protodioscin (5 and 10 mg/kg) continuously for 6 weeks, respectively. The glucose intolerance, serum uric acid (UA), blood urea nitrogen (BUN), creatinine (Cr), total cholesterol (TC), triglyceride (TG), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were determined.

RESULTS

Protodioscin significantly improved glucose intolerance and reduced the levels of serum UA, BUN, Cr, TC and TG. Histological examinations showed that protodioscin ameliorated glomerular and tubular pathological changes. Protodioscin significantly reduced renal concentrations of IL-1β, IL-6 and TNF-α by inhibiting the activation of nuclear factor-κB, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase and extracellular signal-regulated kinase. In addition, the effect of protodioscin on the mitogen activated protein kinases (MAPK) pathway was examined.

CONCLUSION

Taken together, protodioscin is a potential drug candidate for high dietary fructose-induced metabolic syndrome and renal injury.