Berberine enhances the AMPK activation and autophagy and mitigates high glucose-induced apoptosis of mouse podocytes

Lycopene attenuates high glucose-mediated apoptosis in MPC5 podocytes by promoting autophagy via the PI3K/AKT signaling pathway

Podocyte injury serves an important role during the progression of diabetic nephropathy (DN), and lycopene (Lyc) may display a potential protective effect against DN progression. The effects of Lyc on high glucose (HG)-induced podocyte apoptosis and the underlying mechanisms are not completely understood; therefore, the present study aimed to investigate the effects of Lyc on HG-induced MPC5 podocyte apoptosis and the underlying mechanism. In the present study, MPC5 podocytes were exposed to HG and different doses of Lyc. MPC5 podocyte viability and apoptosis were assessed by performing the MTT assay and flow cytometry, respectively. To explore the effects of Lyc on the PI3K/AKT signaling pathway and autophagy, LY294002 (LY) and 3-methyladenine (3-MA) were used as PI3K and autophagy inhibitors, respectively. The expression levels of nephrin, podocin, apoptosis-related proteins (Bax, Bcl-2 and cleaved caspase-3), autophagy-related proteins [Beclin-1 and microtubule associated protein 1 light chain 3 (LC3)II/LC3I] and certain key proteins involved in the PI3K/AKT signaling pathway were measured via western blotting. The results suggested that Lyc reversed the inhibitory effect of HG on cell viability, and the protein expression levels of nephrin and podocin, as well as the promoting effect of HG on MPC5 podocyte apoptosis. In addition, under HG conditions, Lyc upregulated the phosphorylation levels of PI3K and AKT, and reduced HG- and LY-mediated MPC5 podocyte apoptosis. Moreover, Lyc further increased HG-induced protein expression levels of Beclin-1 and LC3II/LC3I, and attenuated LY-mediated inhibition of HG-induced MPC5 podocyte autophagy. In addition, the effects of Lyc on HG-mediated MPC5 podocyte apoptosis were alleviated by 3-MA. Therefore, the present study suggested that Lyc may protect against HG-induced MPC5 podocyte apoptosis by promoting autophagy activity via activation of the PI3K/AKT signaling pathway.

Berberine, a natural alkaloid sensitizes human hepatocarcinoma to ionizing radiation by blocking autophagy and cell cycle arrest resulting in senescence

OBJECTIVE

To study the radiosensitizing potential of Berberine and the underlying mechanism in human hepatocarcinoma (HepG2) cells.

METHODS

HepG2 cells were challenged with X-rays in combination with Berberine treatment and several in vitro assays were performed. Alteration in cell viability was determined by MTT assay. Changes in intracellular ROS levels, mitochondrial membrane potential/mass, intracellular acidic vesicular organelles as well as cell cycle arrest and apoptotic cell death were analysed by flow cytometry. Induction of autophagy was assessed by staining the cells with Monodansylcadaverine/Lysotracker red dyes and immunoblotting for LC3I/II and p62 proteins. Phase-contrast/fluorescence microscopy was employed to study mitotic catastrophe and senescence. Cellular senescence was confirmed by immunoblotting for p21 levels and ELISA for Interleukin-6.

KEY FINDINGS

X-rays + Berberine had a synergistic effect in reducing cell proliferation accompanied by a robust G2/M arrest. Berberine-mediated radiosensitization was associated with elevated levels of LC3II and p62 suggesting blocked autophagy that was followed by mitotic catastrophe and senescence. Treatment of cells with X-rays + Berberine resulted in increased oxidative stress, hyperpolarized mitochondria with increased mitochondrial mass and reduced ATP levels.

CONCLUSIONS

The study expands the understanding of the pharmacological properties of Berberine and its applicability as a radiosensitizer towards treating liver cancer.

Regulation of podocytes function by AMP-activated protein kinase

Podocytes are unique, highly specialized, terminally differentiated cells that form an essential, integral part of the glomerular filter. These cells limit the outside border of the glomerular basement membrane, forming a tight barrier that prevents significant protein loss from the capillary space. The slit diaphragm formed by podocytes is crucial for maintaining glomerular integrity and function. They are the target of injury in many glomerular diseases, including hypertension and diabetes mellitus. Accumulating studies have revealed that AMP-activated protein kinase (AMPK), an essential cellular energy sensor, might play a fundamental role in regulating podocyte metabolism and function. AMPK participates in insulin signaling, therefore controls glucose uptake and podocytes insulin sensitivity. It is also involved in insulin-dependent cytoskeleton reorganization in podocytes, mediating glomerular albumin permeability. AMPK plays an important role in the regulation of autophagy/apoptosis processes, which influence podocytes viability. The present review aimed to highlight the molecular mechanisms associated with AMPK that are involved in the regulation of podocyte function in health and disease states.

AMPK in microvascular complications of diabetes and the beneficial effects of AMPK activators from plants

BACKGROUND

Diabetes mellitus is a multifactorial disorder with the risk of micro- and macro-vascular complications. High glucose-induced derangements in metabolic pathways are primarily associated with the initiation and progression of secondary complications namely, diabetic nephropathy, neuropathy, and retinopathy. Adenosine monophosphate-activated protein kinase (AMPK) has emerged as an attractive therapeutic target to treat various metabolic disorders including diabetes mellitus. It is a master metabolic regulator that helps in maintaining cellular energy homeostasis by promoting ATP-generating catabolic pathways and inhibiting ATP-consuming anabolic pathways. Numerous pharmacological and plant-derived bioactive compounds that increase AMP-activated protein kinase activation has shown beneficial effects by mitigating secondary complications namely retinopathy, nephropathy, and neuropathy.

PURPOSE

The purpose of this review is to highlight current knowledge on the role of AMPK and its activators from plant origin in diabetic microvascular complications.

METHODS

Search engines such as Google Scholar, PubMed, Science Direct and Web of Science are used to extract papers using relevant key words. Papers mainly focusing on the role of AMPK and AMPK activators from plant origin in diabetic nephropathy, retinopathy, and neuropathy was chosen to be highlighted.

RESULTS

According to results, decrease in AMPK activation during diabetes play a causative role in the pathogenesis of diabetic microvascular complications. Some of the plant-derived bioactive compounds were beneficial in restoring AMPK activity and ameliorating diabetic microvascular complications.

CONCLUSION

AMPK activators from plant origin are beneficial in mitigating diabetic microvascular complications. These pieces of evidence will be helpful in the development of AMPK-centric therapies to mitigate diabetic microvascular complications.

MicroRNA and mRNA analysis of angiotensin II-induced renal artery endothelial cell dysfunction

Continuous activation of angiotensin II (Ang II) induces renal vascular endothelial dysfunction, inflammation and oxidative stress, all of which may contribute to renal damage. MicroRNAs (miRs/miRNAs) play a crucial regulatory role in the pathogenesis of hypertensive nephropathy (HN). The present study aimed to assess the differential expression profiles of potential candidate genes involved in Ang II-induced rat renal artery endothelial cell (RRAEC) dysfunction and explore their possible functions. In the present study, the changes in energy metabolism and autophagy function in RRAECs were evaluated using the Seahorse XF Glycolysis Stress Test and dansylcadaverine/transmission electron microscopy following exposure to Ang II. Subsequently, mRNA-miRNA sequencing experiments were performed to determine the differential expression profiles of mRNAs and miRNAs. Integrated bioinformatics analysis was applied to further explore the molecular mechanisms of Ang II on endothelial injury induced by Ang II. The present data supported the notion that Ang II upregulated glycolysis levels and promoted autophagy activation in RRAECs. The sequencing data demonstrated that 443 mRNAs and 58 miRNAs were differentially expressed (DE) in response to Ang II exposure, where 66 mRNAs and 55 miRNAs were upregulated, while 377 mRNAs and 3 miRNAs were downregulated (fold change >1.5 or <0.67; P<0.05). Functional analysis indicated that DE mRNA and DE miRNA target genes were mainly associated with cell metabolism (metabolic pathways), differentiation (Th1 and Th2 cell differentiation), autophagy (autophagy-animal and autophagy-other) and repair (RNA-repair). To the best of the authors' knowledge, this is the first report on mRNA-miRNA integrated profiles of Ang II-induced RRAECs. The present results provided evidence suggesting that the miRNA-mediated effect on the ‘mTOR signaling pathway’ might play a role in Ang II-induced RRAEC injury by driving glycolysis and autophagy activation. Targeting miRNAs and their associated pathways may provide valuable insight into the clinical management of HN and may improve patient outcome.

Highly bioavailable berberine formulation ameliorates diabetic nephropathy through the inhibition of glomerular mesangial matrix expansion and the activation of autophagy

Glomerular mesangial matrix expansion and cell autophagy are the most important factors in the development of kidney damage under diabetic conditions. The activation of AMPK might be an important treatment target for diabetic nephropathy. Berberine has multiple effects on all types of diabetic complications as an activator of AMPK. However, the poor bioavailability of berberine limits its clinical applications. Huang-Gui Solid Dispersion (HGSD), a new formulation of berberine developed in our lab, has 4-fold greater bioavailability than berberine. However, its therapeutic application and mechanism still need to be explored. In the present study, the effect of HGSD on kidney function in type 2 diabetic rats and db/db mice was investigated. The results demonstrated that HGSD improved kidney function in these two animal models, decreased the glomerular volume and increased autophagy. Meanwhile, AMPK phosphorylation levels and autophagy-related protein expression were significantly increased, and extracellular matrix protein deposition-related protein expression was decreased after treatment. The present study indicated that HGSD protected against diabetic kidney dysfunction by inhibiting glomerular mesangial matrix expansion and activating autophagy. The mechanism of HGSD in the treatment of diabetic nephropathy might be connected to the activation of AMPK phosphorylation.

Berberine for prevention of dementia associated with diabetes and its comorbidities: A systematic review

BACKGROUND

A growing number of epidemiological studies indicate that metabolic syndrome (MetS) and its associated features play a key role in the development of certain degenerative brain disorders, including Alzheimer's disease and vascular dementia. Produced by several different medicinal plants, berberine is a bioactive alkaloid with a wide range of pharmacological effects, including antidiabetic effects. However, it is not clear whether berberine could prevent the development of dementia in association with diabetes.

OBJECTIVE

To give an overview of the therapeutic potential of berberine as a treatment for dementia associated with diabetes.

SEARCH STRATEGY

Database searches A and B were conducted using PubMed and ScienceDirect. In search A, studies on berberine's antidementia activities were identified using "berberine" and "dementia" as search terms. In search B, recent studies on berberine's effects on diabetes were surveyed using "berberine" and "diabetes" as search terms.

INCLUSION CRITERIA

Clinical and preclinical studies that investigated berberine's effects associated with MetS and cognitive dysfunction were included.

DATA EXTRACTION AND ANALYSIS

Data from studies were extracted by one author, and checked by a second; quality assessments were performed independently by two authors.

RESULTS

In search A, 61 articles were identified, and 22 original research articles were selected. In search B, 458 articles were identified, of which 101 were deemed relevant and selected. Three duplicates were removed, and a total of 120 articles were reviewed for this study. The results demonstrate that berberine exerts beneficial effects directly in the brain: enhancing cholinergic neurotransmission, improving cerebral blood flow, protecting neurons from inflammation, limiting hyperphosphorylation of tau and facilitating β-amyloid peptide clearance. In addition, evidence is growing that berberine is effective against diabetes and associated disorders, such as atherosclerosis, cardiomyopathy, hypertension, hepatic steatosis, diabetic nephropathy, gut dysbiosis, retinopathy and neuropathy, suggesting indirect benefits for the prevention of dementia.

CONCLUSION

Berberine could impede the development of dementia via multiple mechanisms: preventing brain damages and enhancing cognition directly in the brain, and indirectly through alleviating risk factors such as metabolic dysfunction, and cardiovascular, kidney and liver diseases. This study provided evidence to support the value of berberine in the prevention of dementia associated with MetS.

Autophagy Function and Regulation in Kidney Disease

Autophagy is a dynamic process by which intracellular damaged macromolecules and organelles are degraded and recycled for the synthesis of new cellular components. Basal autophagy in the kidney acts as a quality control system and is vital for cellular metabolic and organelle homeostasis. Under pathological conditions, autophagy facilitates cellular adaptation; however, activation of autophagy in response to renal injury may be insufficient to provide protection, especially under dysregulated conditions. Kidney-specific deletion of Atg genes in mice has consistently demonstrated worsened acute kidney injury (AKI) outcomes supporting the notion of a pro-survival role of autophagy. Recent studies have also begun to unfold the role of autophagy in progressive renal disease and subsequent fibrosis. Autophagy also influences tubular cell death in renal injury. In this review, we reported the current understanding of autophagy regulation and its role in the pathogenesis of renal injury. In particular, the classic mammalian target of rapamycin (mTOR)-dependent signaling pathway and other mTOR-independent alternative signaling pathways of autophagy regulation were described. Finally, we summarized the impact of autophagy activation on different forms of cell death, including apoptosis and regulated necrosis, associated with the pathophysiology of renal injury. Understanding the regulatory mechanisms of autophagy would identify important targets for therapeutic approaches.

Research Progress on the Pathological Mechanisms of Podocytes in Diabetic Nephropathy

Diabetic nephropathy (DN) is not only an important microvascular complication of diabetes but also the main cause of end-stage renal disease. Studies have shown that the occurrence and development of DN are closely related to morphological and functional changes in podocytes. A series of morphological changes after podocyte injury in DN mainly include podocyte hypertrophy, podocyte epithelial-mesenchymal transdifferentiation, podocyte detachment, and podocyte apoptosis; functional changes mainly involve podocyte autophagy. More and more studies have shown that multiple signaling pathways play important roles in the progression of podocyte injury in DN. Here, we review research progress on the pathological mechanism of morphological and functional changes in podocytes associated with DN, to provide a new target for delaying the occurrence and development of this disorder.

Mechanisms of Herbal Nephroprotection in diabetes mellitus

Diabetic nephropathy (DN) is a leading cause of kidney morbidity. Despite the multilayered complexity of the mechanisms involved in the pathogenesis of DN, the conventional treatment is limited to just a few drug classes fraught with the risk of adverse events, including the progression of renal dysfunction. Phytoceuticals offer a promising alternative as they act on the many-sidedness of DN pathophysiology, multitargeting its intricacies. This paper offers a review of the mechanisms underlying the protective action of these phytoagents, including boosting the antioxidant capabilities, suppression of inflammation, averting the proliferative and sclerosing/fibrosing events. The pathogenesis of DN is viewed as a continuum going from the original offense, high glucose, through the noxious products it generates (advanced glycation end-products, products of oxidative and nitrosative stress) and the signaling chains consequently brought into action, to the harmful mediators of inflammation, sclerosis, and proliferation that eventually lead to DN, despite the countervailing attempts of the protective mechanisms. Special attention was given to the various pathways involved, pointing out the ability of the phytoagents to hinder the deleterious ones (especially those leading to, driven by, or associated with TGF-β activation, SREBP, Smad, MAPK, PKC, NF-κB, NLRP3 inflammasome, and caspase), to promote the protective ones (PPAR-α, PPAR-γ, EP4/Gs/AC/cAMP, Nrf2, AMPK, and SIRT1), and to favorably modulate those with potentially dual effect (PI3K/Akt). Many phytomedicines have emerged as potentially useful out of in vitro and in vivo studies, but the scarcity of human trials seriously undermines their usage in the current clinical practice-an issue that stringently needs to be addressed.

Role of Long Non-Coding RNA (LncRNA) LINC-PINT Downregulation in Cardiomyopathy and Retinopathy Progression Among Patients with Type 2 Diabetes

Background

Despite the acknowledgement that LncRNA LINC-PINT may inhibit tumor cell invasion in human cancers, it is not yet determined when it comes to diabetes and its related complications.

Material/Methods

There were 244 patients with T2D and 126 healthy volunteers were admitted to People’s Hospital of Xinjiang Uygur Autonomous Region Hospital. Fasting blood (5 mL) was obtained from the patients and controls a day after admission. The diabetes patients’ fasting blood was extracted once every 6 months during follow-up. The total RNA was extracted and then used for detecting the expression of LINC-PINT.

Results

A comparison was made in this study, where LINC-PINT did not experience significant downregulation level in the majority of those suffering diabetes complications when in contrast to healthy controls, while LINC-PINT expression was found in diabetics. The follow-up study showed that LINC-PINT was downregulated in patients who developed cardiomyopathy and retinopathy or both but not in patients who developed other complications. Treatment with high glucose limited the extent of LINC-PINT expression in the ARPE-19 and AC16 cells. While the overexpression of LINC-PINT increased the viability of ARPE-19 and AC16 cells, siRNA-mediated silencing of LINC-PINT elicited the opposite effect.

Conclusions

Hence, we concluded that the overexpression of LINC-PINT may exhibit inhibitory effects on the progression of cardiomyopathy and retinopathy among patients with type 2 diabetes.

Oxidative stress, nutritional antioxidants and beyond

Free radical-induced oxidative stress contributes to the development of metabolic syndromes (Mets), including overweight, hyperglycemia, insulin resistance and pro-inflammatory state. Most free radicals are generated from the mitochondrial electron transport chain; under physiological conditions, their levels are maintained by efficient antioxidant systems. A variety of transcription factors have been identified and characterized that control gene expression in response to oxidative stress status. Natural antioxidant compounds have been largely studied for their strong antioxidant capacities. This review discusses the recent progress in oxidative stress and mitochondrial dysfunction in Mets and highlights the anti-Mets, anti-oxidative, and anti-inflammatory effect of polyphenols as potential nutritional therapy.

PGC-1α, a potential therapeutic target against kidney aging

Aging is defined as changes in an organism over time. The proportion of the aged population is markedly increasing worldwide. The kidney, as an essential organ with a high energy requirement, is one of the most susceptible organs to aging. It is involved in glucose metabolism via gluconeogenesis, glucose filtration and reabsorption, and glucose utilization. Proximal tubular epithelial cells (PTECs) depend on lipid metabolism to meet the high demand for ATP. Recent studies have shown that aging‐related kidney dysfunction is highly associated with metabolic changes in the kidney. Peroxisome proliferator‐activated receptor gamma coactivator‐1 alpha (PGC‐1α), a transcriptional coactivator, plays a major role in the regulation of mitochondrial biogenesis, peroxisomal biogenesis, and glucose and lipid metabolism. PGC‐1α is abundant in tissues, including kidney PTECs, which demand high energy. Many in vitro and in vivo studies have demonstrated that the activation of PGC‐1α by genetic or pharmacological intervention prevents telomere shortening and aging‐related changes in the skeletal muscle, heart, and brain. The activation of PGC‐1α can also prevent kidney dysfunction in various kidney diseases. Therefore, a better understanding of the effect of PGC‐1α activation in various organs on aging and kidney diseases may unveil a potential therapeutic strategy against kidney aging.

CAV1-CAVIN1-LC3B-mediated autophagy regulates high glucose-stimulated LDL transcytosis

Diabetes is a recognized high-risk factor for the development of atherosclerosis, in which macroautophagy/autophagy is emerging to play essential roles. The retention of low-density lipoprotein (LDL) particles in subendothelial space following transcytosis across the endothelium is the initial step of atherosclerosis. Here, we identified that high glucose could promote atherosclerosis by stimulating transcytosis of LDL. By inhibiting AMPK-MTOR-PIK3C3 pathway, high glucose suppresses the CAV-CAVIN-LC3B-mediated autophagic degradation of CAV1; therefore, more CAV1 is accumulated in the cytosol and utilized to form more caveolae in the cell membrane and facilitates the LDL transcytosis across endothelial cells. For a proof of concept, higher levels of lipids were accumulated in the subendothelial space of umbilical venous walls from pregnant women with gestational diabetes mellitus (GDM), compared to those of pregnant women without GDM. Our results reveal that high glucose stimulates LDL transcytosis by a novel CAV1-CAVIN1-LC3B signaling-mediated autophagic degradation pathway.

ABBREVIATIONS

3-MA: 3-methyladenine; ACTB: actin beta; AMPK: AMP-activated protein kinase; Bafi: bafilomycin A₁; CAV1: caveolin-1; CAVIN1: caveolae associated protein 1; CSD: the CAV1 scaffolding domain; GDM: gestational diabetes mellitus; IMD: intramembrane domain; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule- associated protein 1 light chain 3; MFI: mean fluorescence intensity; MTOR: mechanistic target of rapamycin kinase; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; SQSTM1/p62: sequestosome 1.

Berberine as a potential autophagy modulator

Today, pharmacognosy is considered a valuable science in the prevention and treatment of diseases. Among herbals, Berberine is an isoquinoline alkaloid found in the Berberis species. Surprisingly, it shows antimicrobial, antiviral, antidiarrheal, antipyretic, and anti-inflammatory potential. Furthermore, it diminishes drug resistance in cancer therapy and enhances tumor suppression in part through autophagy and cell cycle arrest mechanisms. In the present review, we discuss the effect of berberine on diverse cellular pathways and describe how berberine acts as an autophagy modulator to adjust physiologic and pathologic conditions and diminishes drug resistance in cancer therapy.

Berberine improved experimental chronic colitis by regulating interferon-γ- and IL-17A-producing lamina propria CD4+ T cells through AMPK activation

The herbal medicine berberine (BBR) has been recently shown to be an AMP-activated protein kinase (AMPK) productive activator with various properties that induce anti-inflammatory responses. We investigated the effects of BBR on the mechanisms of mucosal CD4+T cell activation in vitro and on the inflammatory responses in T cell transfer mouse models of inflammatory bowel disease (IBD). We examined the favorable effects of BBR in vitro, using lamina propria (LP) CD4+ T cells in T cell transfer IBD models in which SCID mice had been injected with CD4+CD45RBhigh T cells. BBR suppressed the frequency of IFN-γ- and Il-17A-producing LP CD4+ T cells. This effect was found to be regulated by AMPK activation possibly induced by oxidative phosphorylation inhibition. We then examined the effects of BBR on the same IBD models in vivo. BBR-fed mice showed AMPK activation in the LPCD4+ T cells and an improvement of colitis. Our study newly showed that the BBR-induced AMPK activation of mucosal CD4+ T cells resulted in an improvement of IBD and underscored the importance of AMPK activity in colonic inflammation.

Molecular Interactions Between Reactive Oxygen Species and Autophagy in Kidney Disease

Reactive oxygen species (ROS) are highly reactive signaling molecules that maintain redox homeostasis in mammalian cells. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of ROS, culminating in oxidative stress and the associated oxidative damage of cellular components. ROS and oxidative stress play a vital role in the pathogenesis of acute kidney injury and chronic kidney disease, and it is well documented that increased oxidative stress in patients enhances the progression of renal diseases. Oxidative stress activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular oxidized and damaged macromolecules and dysfunctional organelles. In this review, we report the current understanding of the molecular regulation of autophagy in response to oxidative stress in general and in the pathogenesis of kidney diseases. We summarize how the molecular interactions between ROS and autophagy involve ROS-mediated activation of autophagy and autophagy-mediated reduction of oxidative stress. In particular, we describe how ROS impact various signaling pathways of autophagy, including mTORC1-ULK1, AMPK-mTORC1-ULK1, and Keap1-Nrf2-p62, as well as selective autophagy including mitophagy and pexophagy. Precise elucidation of the molecular mechanisms of interactions between ROS and autophagy in the pathogenesis of renal diseases may identify novel targets for development of drugs for preventing renal injury.

Protective effect of silencing Stat1 on high glucose-induced podocytes injury via Forkhead transcription factor O1-regulated the oxidative stress response

Background

Podocyte plays an important role in maintaining the integrity and function of the glomerular filtration barrier. Various studies reported that forkhead transcription factor (Fox) O1 played a key role in anti-oxidative signaling. This study aimed to investigate the role of Stat1 in high glucose (HG) -induced podocyte injury.

Methods

Under normal glucose, hypertonic and HG stimulated podocyte conditions, cell counting kit-8 (CCK-8) assay, flow cytometry and western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were respectively carried out to determine cell viability, apoptosis, reactive oxygen species (ROS) production and related genes expressions. We then respectively used silent Stat1, simultaneous silencing Stat1 and FoxO1 and over-expression of FoxO1, to observe whether they/it could reverse the damage of podocytes induced by HG.

Results

High glucose attenuated cell survival and promoted cell apoptosis in MPC-5 cells at the same time, and it was also observed to promote the protein expression of Stat1 and the FoxO1 expression inhibition. Silencing Stat1 could reverse HG-induced podocytes injury. Specifically, siStat1 increased cell viability, inhibited cell apoptosis and attenuated ROS level in a high-glucose environment. Cleaved caspase-3 and pro-apoptosis protein Bax was significantly down-regulated, and anti-apoptosis protein Bcl-2 was up-regulated by siStat1. The antioxidant genes Catalase, MnSOD, NQO1 and HO1 were up-regulated by siStat1. We found that silencing FoxO1 reversed the protective effect of siStat1 on the HG-induced podocytes injury.

Conclusions

Silencing Stat1 could reverse the effects of high glucose-triggered low cell viability, cell apoptosis and ROS release and the functions of Stat1 might be involved in FoxO1 mediated-oxidative stress in nucleus.

Grem2 mediates podocyte apoptosis in high glucose milieu

BACKGROUND

Increased DAN protein (Grem1, Grem2, Grem3, Cerberus, NBL1, SOST, and USAG1) levels are often associated with severe disease-states in adult kidneys. Grem1, SOST, and USAG1 have been demonstrated to be upregulated and play a critical role in the progression of diabetic nephropathy (DN); however, the expression and the role of other DAN family members in DN have not been reported yet. In this study, we investigated the expression and the role of Grem2 in the development of renal lesions in mice with type 2 DN.

METHODS

Fourteen-week-old BTBR^ob/ob (a mouse model of type 2 diabetes mellitus) and control (BTBR, wild type) mice were evaluated for renal functional and structural biomarkers. Urine was collected for protein content assay, and renal tissues were harvested for molecular analysis with real-time PCR, Western blotting, and immunohistochemistry. In vitro studies, human podocytes were transfected with Grem2 plasmid and were evaluated for apoptosis (morphologic assay and Western blotting). To evaluate the Grem2-mediated downstream signaling, the phosphorylation status of Smad2/3 and Smad1/5/8 was assessed. To establish a causal relationship, the effect of SIS3 (an inhibitor for Samd2/3) and BMP-7 (an agonist for Smad1/5/8) was evaluated on Germ2-induced podocyte apoptosis.

RESULTS

BTBR^ob/ob mice showed elevated urinary protein levels. Renal tissues of BTBR^ob/ob mice showed an increased expression of Grem2; both glomerular and tubular cells displayed enhanced Grem2 expression. In vitro studies, high glucose increased Grem2 expression in cultured human podocytes, whereas, Grem2 silencing partially protected podocyte from high glucose-induced apoptosis. Overexpression of Grem2 in podocytes not only increased Bax/Bcl2 expression ratio but also promoted podocyte apoptosis; moreover, an overexpression of Grem2 increased the phosphorylation of Smad2/3 and decreased the phosphorylation of Smad1/5/8; furthermore, SIS3 and BMP-7 attenuated Grem2-induced podocyte apoptosis.

CONCLUSIONS

High glucose increases Grem2 expression in kidney cells. Grem2 mediates podocyte apoptosis through Smads.

Berberine Protects Glomerular Podocytes via Inhibiting Drp1-Mediated Mitochondrial Fission and Dysfunction

Elevated levels of plasma free fatty acid (FFA) and disturbed mitochondrial dynamics play crucial roles in the pathogenesis of diabetic kidney disease (DKD). However, the mechanisms by which FFA leads to mitochondrial damage in glomerular podocytes of DKD and the effects of Berberine (BBR) on podocytes are not fully understood.

Methods: Using the db/db diabetic mice model and cultured mouse podocytes, we investigated the molecular mechanism of FFA-induced disturbance of mitochondrial dynamics in podocytes and testified the effects of BBR on regulating mitochondrial dysfunction, podocyte apoptosis and glomerulopathy in the progression of DKD.

Results: Intragastric administration of BBR for 8 weeks in db/db mice significantly reversed glucose and lipid metabolism disorders, podocyte damage, basement membrane thickening, mesangial expansion and glomerulosclerosis. BBR strongly inhibited podocyte apoptosis, increased reactive oxygen species (ROS) generation, mitochondrial fragmentation and dysfunction both in vivo and in vitro. Mechanistically, BBR could stabilize mitochondrial morphology in podocytes via abolishing palmitic acid (PA)-induced activation of dynamin-related protein 1 (Drp1).

Conclusions: Our study demonstrated for the first time that BBR may have a previously unrecognized role in protecting glomerulus and podocytes via positively regulating Drp1-mediated mitochondrial dynamics. It might serve as a novel therapeutic drug for the treatment of DKD.

A Natural Isoquinoline Alkaloid With Antitumor Activity: Studies of the Biological Activities of Berberine

Coptis, a traditional medicinal plant, has been used widely in the field of traditional Chinese medicine for many years. More recently, the chemical composition and bioactivity of Coptis have been studied worldwide. Berberine is a main component of Rhizoma Coptidis. Modern medicine has confirmed that berberine has pharmacological activities, such as anti-inflammatory, analgesic, antimicrobial, hypolipidemic, and blood pressure-lowering effects. Importantly, the active ingredient of berberine has clear inhibitory effects on various cancers, including colorectal cancer, lung cancer, ovarian cancer, prostate cancer, liver cancer, and cervical cancer. Cancer, ranked as one of the world’s five major incurable diseases by WHO, is a serious threat to the quality of human life. Here, we try to outline how berberine exerts antitumor effects through the regulation of different molecular pathways. In addition, the berberine-mediated regulation of epigenetic mechanisms that may be associated with the prevention of malignant tumors is described. Thus, this review provides a theoretical basis for the biological functions of berberine and its further use in the clinical treatment of cancer.

Calpain-10 drives podocyte apoptosis and renal injury in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a progressive microvascular complication of diabetes mellitus (DM), driven largely by podocyte apoptosis. The cysteine protease Calpain 10 is known to augment apoptosis and necrosis, and is a potential therapeutic target in DN.

METHODS

Type 2 diabetes was induced in SD rats by high-fat diet (HFD) feeding and streptozotocin (STZ) injections, and simulated in vitro by culturing conditionally immortalized mouse podocytes in hyperlipidemic (PA, 100 μM) conditions. The rate of apoptosis in the renal tissues and cultured podocytes was determined by TUNEL assay. The expression of Calpain 10 and its biological effects were assayed by real-time PCR, Western blotting, immunofluorescence and electron microscopy.

RESULTS

Calpain 10 was up-regulated in the kidneys of DN rats, as well as immortalized mouse podocytes. High levels of Calpain 10 was associated with renal dysfunction and tissue destruction, and podocyte injury and apoptosis. Knockdown of Calpain 10 protected podocytes by decreasing apoptosis rate, and upregulated nephrin.

CONCLUSION

Calpain 10 is a pro-apoptotic factor in DN, and can be targeted for treating glomerular diseases.

Combating Neurodegenerative Diseases with the Plant Alkaloid Berberine: Molecular Mechanisms and Therapeutic Potential

Neurodegenerative diseases are among the most serious health problems affecting millions of people worldwide. Such diseases are characterized by a progressive degeneration and / or death of neurons in the central nervous system. Currently, there are no therapeutic approaches to cure or even halt the progression of neurodegenerative diseases. During the last two decades, much attention has been paid to the neuroprotective and anti-neurodegenerative activities of compounds isolated from natural products with high efficacy and low toxicity. Accumulating evidence indicates that berberine, an isoquinoline alkaloid isolated from traditional Chinese medicinal herbs, may act as a promising anti-neurodegenerative agent by inhibiting the activity of the most important pathogenic enzymes, ameliorating intracellular oxidative stress, attenuating neuroinflammation, triggering autophagy and protecting neurons against apoptotic cell death. This review attempts to summarize the current state of knowledge regarding the therapeutic potential of berberine against neurodegenerative diseases, with a focus on the molecular mechanisms that underlie its effects on Alzheimer's, Parkinson's and Huntington's diseases.

Chinese Herbal Medicine in Ameliorating Diabetic Kidney Disease via Activating Autophagy

Diabetic kidney disease (DKD), a leading cause of end-stage renal disease (ESRD), has become a serious public health problem worldwide and lacks effective therapies due to its complex pathogenesis. Recent studies suggested defective autophagy involved in the pathogenesis and progression of DKD. Chinese herbal medicine, as an emerging option for the treatment of DKD, could improve diabetic kidney injury by activating autophagy. In this review, we briefly summarize underlying mechanisms of autophagy dysregulation in DKD, including AMP-activated protein kinase (AMPK), the mechanistic target of rapamycin (mTOR), and the sirtuin (Sirt) pathways, and we particularly concentrate on the current status of Chinese herbal medicine treating DKD by regulating autophagy. The advances in our understanding regarding the treatment of DKD via regulating autophagy with Chinese herbal medicine will enhance the clinical application of Chinese medicine as well as discovery of novel therapeutic agents for diabetic patients.

Cell Apoptosis and Autophagy in Renal Fibrosis

Renal fibrosis is the final common pathway of all chronic kidney diseases progressing to end-stage renal diseases. Autophagy, a highly conserved lysosomal degradation pathway, plays important roles in maintaining cellular homeostasis in all major types of kidney cells including renal tubular cells as well as podocytes, mesangial cells and endothelial cells in glomeruli. Autophagy dysfunction is implicated in the pathogenesis of various renal pathologies. Here, we analyze the pathological role and regulation of autophagy in renal fibrosis and related kidney diseases in both glomeruli and tubulointerstitial compartments. Further research is expected to gain significant mechanistic insights and discover pathway-specific and kidney-selective therapies targeting autophagy to prevent renal fibrosis and related kidney diseases.

The protective effects of rapamycin on cell autophagy in the renal tissues of rats with diabetic nephropathy via mTOR-S6K1-LC3II signaling pathway

BACKGROUND

Previous studies have shown that podocyte autophagy is an important trigger for proteinuria and glomerulosclerosis. The mammalian rapamycin target protein (mTOR) occupies a pivotal position in the autophagy pathway. In this study, we planned to clarify the mechanism of mTOR regulation of podocyte autophagy and the effect of rapamycin (RAPA).

METHODS

All rats were randomly divided into normal control group (n = 8), DN group (n = 8), and RAPA group (n = 8). Blood and urine samples were collected at the 4th, 8th, and 12th weeks of the experiment. The serum creatinine (Scr), urine volume levels, and the 24 h urine protein (UP) levels were examined. The nephrin, podocin, mTOR, ribosomal S6 kinase 1 (S6K1), and autophagy marker light chain 3 (LC3II) expression levels were evaluated by immunohistochemistry, quantitative PCR, and immunoblotting.

RESULTS

The urine volume, 24 h UP, and Scr of the DN and RAPA groups increased significantly compared with the NC group (p < .05). Nephrin and podocin expression was decreased in the kidney tissues of the DN and RAPA groups compared with the NC group (p < .05). The expression levels of mTOR and S6K1 increased and LC3II expression decreased in the renal tissues of the DN and RAPA groups compared with the NC group (p < .05). After RAPA treatment, all the above indexes were improved compared with the DN group (p < .05), but were significantly abnormal compared with the NC group (p < .05).

CONCLUSION

The proteinuria and kidney function had improved after RAPA treatment. These results confirmed that RAPA specifically binds to mTOR kinase, and inhibits mTOR activity, thereby regulating the pathological autophagic process.

Protective effect of irbesartan against doxorubicin-induced nephrotoxicity in rats: implication of AMPK, PI3K/Akt, and mTOR signaling pathways

Nephrotoxicity is one of the serious undesirable effects related to doxorubicin (DOX). Herein, we have investigated the potential protective effect of irbesartan (IRB) against chronic nephrotoxicity induced by DOX, and the implication of different mechanistic pathways underlying these effects. Rats were treated with either DOX (2.5 mg/kg i.p., 3 times/week) for 2 weeks, and (or) IRB (40 mg/kg, daily) for 3 weeks. IRB prohibited nephrotoxicity induced by DOX, which was evident by the increase in blood urea nitrogen and creatinine levels and histopathological changes. IRB improved DOX-induced alterations in oxidative status by diminishing lipid peroxidation and upregulating the antioxidant enzymes. Also, upon DOX treatment, the renal expression of tumor necrosis factor-α, interleukin-6, and caspase-3 were significantly increased; IRB diminished DOX-induced alterations in these parameters. Moreover, DOX significantly decreased the expression level of AMP-activated protein kinase (AMPK). Meanwhile, DOX induced activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt/PKB) and mammalian target of rapamycin (mTOR) pathways that cross talked with AMPK. On the contrary, IRB successfully counterbalanced all these effects. Collectively, these outcomes suggest that the modulation of AMPK, PI3K, Akt, and mTOR pathways plays a critical role in conferring the protective effects of IRB against DOX nephrotoxicity.

Supplementation of Abelmoschus manihot Ameliorates Diabetic Nephropathy and Hepatic Steatosis by Activating Autophagy in Mice

Diabetic nephropathy (DN) is a diabetic complication marked by albuminuria and a decline of the glomerular filtration rate. Diabetic kidneys are defective in the autophagy process and mitochondrial function and their enhancement of activity alleviates the pathology. In this paper, we developed a mouse model of DN by a combined treatment of a high-fat diet and streptozotocin after unilateral nephrectomy and supplementation with flower or leaf extracts of Abelmoschus manihot (AM) were tested. The preventive effects of the extracts on DN pathology and changes on autophagy and mitochondrial proteins were investigated. DN mice showed a significant increase in fasting blood glucose, plasma creatinine, blood urea nitrogen, and urinary albumin levels. Periodic acid–Schiff and Sirius red staining of the diabetic kidney presented a significant change in glomerular and tubular structures that was associated with podocyte loss and fibrotic protein accumulation. These changes were attenuated by AM extract treatment in DN mice. In addition, hepatic injury, proinflammatory cytokines, and lipid accumulation were decreased by AM extracts in DN mice. As a protective mechanism, AM extracts significantly increased the expression of proteins by regulating autophagy and mitochondrial dynamics, which potentially prevented the kidney and liver from accumulating pathogenic proteins and dysfunctional mitochondria, which alleviated the progression of DN.

Cytotoxicity of the natural herbicidal chemical, berberine, on Nicotiana tabacum Bright yellow-2 cells

Berberine is a naturally occurring plant secondary metabolite with allelopathic and cytotoxic properties. We investigated the cytotoxic effects of berberine against tobacco Bright Yellow-2 (BY-2) cells. We found that berberine inhibited tobacco BY-2 cell growth in a concentration-dependent manner and the potency of berberine was comparable to the traditional herbicide glyphosate. Meanwhile, the in vivo test revealed that the herbicidal activity of berberine was also comparable to that of glyphosate. Further mechanism studies for the cytotoxicity demonstrated that berberine at concentrations of 40 μg/mL and 80 μg/mL induced cell death by causing mitochondrial membrane depolarization, irregular nuclei and chromatin condensation but not leading to significant apoptosis. Ultra-structure analysis through transmission electron microscopy (TEM) indicated that treatments with 40 μg/mL berberine for 2 d or 80 μg/mL berberine for 1 d induced cell damage, including nuclei morphological changes, cytoplasm and mitochondria degradation and cell wall fibrosis. Treatment at higher concentration of 80 μg/mL for longer period of 2 d, induced plasmolysis and severe damage to basic cell structure, which are indicative of explosive necrosis. Our results suggest that berberine was cytotoxic to tobacco BY-2 cells by inducing necrosis but not apoptosis. Cell wall, mitochondria, nuclei and chromatin were damaged and may be possible primary targets. Therefore, the herbicidal activity of berberine appears to be a complex process associated with multiple mechanisms of action.

Berberine attenuates apoptosis in rat retinal Müller cells stimulated with high glucose via enhancing autophagy and the AMPK/mTOR signaling

Berberine (BBR) has beneficial effects on diabetes and the multiple complications of diabetes due to its anti-apoptotic activity; however, the effect of BBR on diabetic retinopathy and its mechanism of action have not been clarified. The present study investigated the effect of BBR on Müller cells stimulated with high glucose (HG). Primary retinal Müller cells were incubated with high glucose to induce cell apoptosis; cells were pretreated with the AMPK inhibitor compound C and the AMPK activator AICAR to further explore the role of the AMPK/mTOR signaling pathway in the anti-apoptotic action of BBR. Immunofluorescence was used to measure apoptosis and autophagy. Western blot analysis was employed to determine the levels of p-AMPK and p-mTOR, as well as apoptosis-related proteins and autophagy-related proteins in Müller cells. Our results showed that BBR attenuated apoptosis, up regulated Bcl-2 and down regulated Bax and caspase-3 expression; enhanced the formation of autophagy, elevated the expression of Beclin-1 and LC3II and activated the AMPK/mTOR signaling pathway in Müller cells under high glucose conditions compared with the control group. The effect of BBR was partly blocked by compound C and strengthened by AICAR. BBR may have therapeutic potential to protect Müller cells from high-glucose-inducing apoptosis through enhancing autophagy and activating the AMPK/mTOR signaling pathway.

Interactions between oxidative stress, autophagy and apoptosis in A549 cells treated with aged black carbon

After emitted from incomplete combustion of fossil fuels and biomass, ambient black carbon (BC) was then undergone photochemical oxidization processes in the air to form aged BC particles, also called oxidized BC (OBC). This study aimed to investigate the interactions between oxidative stress, autophagy and apoptosis induced by OBC in A549 cells and to explore associated molecular mechanisms. First, OBC could stimulate oxidative stress, autophagy and apoptosis dose-dependently, as evidenced by increased intercellular reactive oxygen species (ROS) levels, up-regulated autophagosome markers (light chain 3, LC3), and elevated apoptosis rate. Inhibitors of oxidative stress (N-acetylcysteine, NAC), autophagy (bafilomycin A1, Baf) and apoptosis (Z-DEVD-FMK) were used to investigate their interactions. NAC pretreatment could significantly reduce autophagy and apoptosis. Additionally, pretreatment with Baf or Z-DEVD-FMK could also significantly suppress the other two biological effects. Furthermore, OBC up regulated the expressions of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), phosphorylated protein kinase B (Akt) and mammalian target of rapamycin (mTOR). The Akt inhibitor (MK-2206) significantly reduced both autophagy and apoptosis. Taken together, dual-direction regulation existed between each two of oxidative stress, autophagy, and apoptosis in A549 cells exposed to OBC. In addition, the autophagy process is modulated by the PI3K/Akt pathway regardless of mTOR activity.

Update on the Benefits and Mechanisms of Action of the Bioactive Vegetal Alkaloid Berberine on Lipid Metabolism and Homeostasis

Elevation of circulating levels of blood cholesterol, especially LDL cholesterol, and/or the decrease of HDL cholesterol levels have long been recognized as primary risk factors for developing atherosclerosis that leads to cardiovascular and cerebrovascular disease. Hypertriglyceridemia is an independent risk factor that is known to contribute to the development of atherosclerosis. Thus, various interventional efforts aimed at reducing hypercholesterolemia and hypertriglyceridemia have been practiced clinically for decades to reduce morbidity and mortality risk associated with deleterious cardiovascular and cerebrovascular events. As such, many drugs have been developed and clinically used to treat hypocholesteremia and/or hypertriglyceridemia; however, dietary approaches including supplements along with changes in nutrition and lifestyle have become increasingly attractive and acceptable methods used to control borderline or moderately increased levels of blood cholesterol and triacylglycerols. In this regard, the use of a plant/herbal bioactive compound, berberine (BBR), has recently been studied extensively in terms of its efficacy as well as its mechanisms of action and safety as an alternative intervention that beneficially modulates blood lipids. The aim of this review is to provide a comprehensive update on BBR research, new concepts and directions in terms of product development and current challenges, and future prospects of using BBR to manage diseases and complications associated with dyslipidemia.

Xiaokeping-induced autophagy protects pancreatic β-cells against apoptosis under high glucose stress

Xiaokeping (XKP), a prescribed Traditional Chinese Medicine (TCM), has been used to treat patients with type Ⅱ diabetes mellitus for many years; however, the molecular mechanism of its effects is unknown. As the only insulin producer, the pancreatic β cell plays an important role in diabetes. Whether XKP influences the viability of pancreatic β cells remains to be substantiated. In the present study, autophagy/apoptosis analyses were used to evaluate the therapeutic effect of XKP on pancreatic β-cells induced by high glucose levels and to investigate a potential causal molecular mechanism of XKP effect on the cells. The pancreatic β-cell lines MIN-6 were divided into four groups: control, high glucose (33.3 mmol/L), high glucose with XKP, high glucose with XKP and 3-Methyladenine (3-MA). Immunofluorescence assay was employed to determine autophagosome formation and flow cytometry was used to determine apoptotic rates of the β cells by the detecting expression of autophagy- and apoptosis-related proteins. High glucose increased the apoptotic rate of β-cells from 5.37% to 23.24%; however addition of XKP mitigated the rate at 10.92%. Data indicate that autophagy of β-cells was induced by XKP via the mammalian target of rapamycin (mTOR) pathway. Where the autophagy inhibitor 3-MA was added, the apoptotic rate was 23.94%, similar to the high glucose group rate. The results suggest a potential cytoprotective effect of XKP from high glucose toxicity by its induction of autophagy which may be linked to mTOR-mediated autophagy.

Berberine suppresses apoptosis and extracellular matrix (ECM) degradation in nucleus pulposus cells and ameliorates disc degeneration in a rodent model

Intervertebral disc degeneration (IVDD) is a chronic disease with complicated pathology involving nucleus pulposus (NP) cell apoptosis and extracellular matrix (ECM) degradation. Previous studies have shown that moderate autophagy has a protective effect against apoptosis in NP cells. Berberine (BBR) is an alkaloid compound with many beneficial properties including antimicrobial, anti-inflammatory, antioxidative, and anti-apoptotic activity. Recently, it was found to induce autophagy in various tissues as well. Thus, we hypothesized that BBR may exert a therapeutic effect on IVDD through autophagy activation. In this study, we investigated the effects of BBR on IVDD and delineated a potential mechanism. BBR treatment in vitro inhibited the expression of pro-apoptotic proteins induced by tert-butyl hydroperoxide (TBHP), and increased the expression of anti-apoptotic Bcl-2. Furthermore, it prevented ECM degradation by inhibiting the production of matrix-degrading enzymes. Additionally, BBR treatment significantly activated autophagy in NP cells. However, autophagy inhibition markedly suppressed BBR's effects on NP cell apoptosis and ECM degeneration, indicating that autophagy activation with BBR treatment is protective against IVDD. In vivo, BBR treatment increased the expression of LC3 in disc cells and prevented the development of IVDD in a needle puncture-induced rat model. Thus, BBR stimulates autophagy as a protective mechanism against NP cell apoptosis and ECM degeneration, revealing its therapeutic potential in the treatment of IVDD.

Advanced glycation end-products suppress autophagic flux in podocytes by activating mammalian target of rapamycin and inhibiting nuclear translocation of transcription factor EB

Insufficient autophagy in podocytes is related to podocyte injury in diabetic nephropathy (DN). Advanced glycation end‐products (AGEs) are major factors of podocyte injury in DN. However, the role and mechanism of AGEs in autophagic dysfunction remain unknown. We investigated autophagic flux in AGE‐stimulated cultured podocytes using multiple assays: western blotting, reverse transcription–quantitative PCR, immunofluorescence staining, and electron microscopy. We also utilized chloroquine and a fluorescent probe to monitor the formation and turnover of autophagosomes. Mice of the db/db strain were used to model diabetes mellitus (DM) with high levels of AGEs. To mimic DM with normal levels of AGEs as a control, we treated db/db mice with pyridoxamine to block AGE formation. AGEs impaired autophagic flux in the cultured podocytes. Compared with db/db mice with normal AGEs but high glucose levels, db/db mice with high AGEs and high glucose levels exhibited lower autophagic activity. Aberrant autophagic flux was related to hyperactive mammalian target of rapamycin (mTOR), a major suppressor of autophagy. Pharmacologic inhibition of mTOR activity restored impaired autophagy. AGEs inhibited the nuclear translocation and activity of the pro‐autophagic transcription factor EB (TFEB) and thus suppressed transcription of its several autophagic target genes. Conversely, TFEB overexpression prevented AGE‐induced autophagy insufficiency. Attenuating mTOR activity recovered TFEB nuclear translocation under AGE stimulation. Co‐immunoprecipitation assays further demonstrated the interaction between mTOR and TFEB in AGE‐stimulated podocytes and in glomeruli from db/db mice. In conclusion, AGEs play a crucial part in suppressing podocyte autophagy under DM conditions. AGEs inhibited the formation and turnover of autophagosomes in podocytes by activating mTOR and inhibiting the nuclear translocation of TFEB. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Berberine ameliorates diabetic nephropathy by inhibiting TLR4/NF-κB pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal failure, contributing to severe morbidity and mortality in diabetic patients. Berberine (BBR) has been well characterized to exert renoprotective effects in DN progression. However, the action mechanism of BBR in DN remains to be fully understood.

METHODS

The DN rat model was generated by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg body weight) while 30 mM high glucose (HG)-treated podocytes were used as an in vitro DN model. The fasting blood glucose level and ratio of kidney weight to body weight were measured after BBR treatment (50, 100, or 200 mg/kg) in STZ-induced DN rats. The renal injury parameters including 24-h urinary protein, blood urea nitrogen and serum creatinine were assessed. qRT-PCR was performed to detect the transcript amounts of inflammatory factors. The concentrations of inflammatory factors were evaluated by ELISA kits. Western blot analysis was conducted to measure the amounts of TLR4/NF-κB-related proteins. The apoptotic rate of podocytes was analyzed by flow cytometry using Annexin V/propidium iodide.

RESULTS

Berberine reduced renal injury in STZ-induced DN rat model, as evidenced by the decrease in fasting blood glucose, ratio of kidney weight to body weight, 24-h urinary protein, serum creatinine, and blood urine nitrogen. BBR attenuated the systemic and renal cortex inflammatory response and inhibited TLR4/NF-κB pathway in STZ-induced DN rats and HG-induced podocytes. Also, HG-induced apoptosis of podocytes was lowered by BBR administration. Furthermore, blockade of TLR4/NF-κB pathway by resatorvid (TAK-242) or pyrrolidine dithiocarbamate aggravated the inhibitory effect of BBR on HG-induced inflammatory response and apoptosis in podocytes.

CONCLUSIONS

Berberine ameliorated DN through relieving STZ-induced renal injury, inflammatory response, and podocyte HG-induced apoptosis via inactivating TLR4/NF-κB pathway.

Update of pathophysiology and management of diabetic kidney disease

Diabetic kidney disease (DKD) is a major cause of morbidity and mortality in patients with diabetes mellitus and the leading cause of end-stage renal disease in the world. The most characteristic marker of DKD is albuminuria, which is associated with renal disease progression and cardiovascular events. Renal hemodynamics changes, oxidative stress, inflammation, hypoxia and overactive renin-angiotensin-aldosterone system (RAAS) are involved in the pathogenesis of DKD, and renal fibrosis plays the key role. Intensified multifactorial interventions, including RAAS blockades, blood pressure and glucose control, and quitting smoking, help to prevent DKD development and progression. In recent years, novel agents are applied for preventing DKD development and progression, including new types of glucose-lowering agents, pentoxifylline, vitamin D analog paricalcitol, pyridoxamine, ruboxistaurin, soludexide, Janus kinase inhibitors and nonsteroidal minerocorticoid receptor antagonists. In this review, recent large studies about DKD are also summarized.

Acute Kidney Injury and Progression of Diabetic Kidney Disease

Diabetic kidney disease, commonly termed diabetic nephropathy (DN), is the most common cause of end-stage kidney disease (ESKD) worldwide. The characteristic histopathology of DN includes glomerular basement membrane thickening, mesangial expansion, nodular glomerular sclerosis, and tubulointerstitial fibrosis. Diabetes is associated with a number of metabolic derangements, such as reactive oxygen species overproduction, hypoxic state, mitochondrial dysfunction, and inflammation. In the past few decades, our knowledge of DN has advanced considerably although much needs to be learned. The traditional paradigm of glomerulus-centered pathophysiology has expanded to the tubule-interstitium, the immune response and inflammation. Biomarkers of proximal tubule injury have been shown to correlate with DN progression, independent of traditional glomerular injury biomarkers such as albuminuria. In this review, we summarize mechanisms of increased susceptibility to acute kidney injury in diabetes mellitus and the roles played by many kidney cell types to facilitate maladaptive responses leading to chronic and end-stage kidney disease.

Autophagy in diabetic kidney disease: regulation, pathological role and therapeutic potential

Diabetic kidney disease, a leading cause of end-stage renal disease, has become a serious public health problem worldwide and lacks effective therapies. Autophagy is a highly conserved lysosomal degradation pathway that removes protein aggregates and damaged organelles to maintain cellular homeostasis. As important stress-responsive machinery, autophagy is involved in the pathogenesis of various diseases. Emerging evidence has suggested that dysregulated autophagy may contribute to both glomerular and tubulointerstitial pathologies in kidneys under diabetic conditions. This review summarizes the recent findings regarding the role of autophagy in the pathogenesis of diabetic kidney disease and highlights the regulation of autophagy by the nutrient-sensing pathways and intracellular stress signaling in this disease. The advances in our understanding of autophagy in diabetic kidney disease will facilitate the discovery of a new therapeutic target for the prevention and treatment of this life-threatening diabetes complication.

The Effects of Berberine on Concanavalin A-Induced Autoimmune Hepatitis (AIH) in Mice and the Adenosine 5'-Monophosphate (AMP)-Activated Protein Kinase (AMPK) Pathway

Background

Berberine, a herbal extract, has been reported to protect against inflammatory disorders. The adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway can be activated by berberine and inhibited by the synthetic, reversible AMP-competitive inhibitor, Compound C. The aim of this study was to investigate the effects of berberine on concanavalin A (Con A)-induced autoimmune hepatitis (AIH) in mice via the AMPK pathway.

Material/Methods

BALB/c mice were treated with berberine, with or without Compound C, followed by treatment with Con A. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured. Liver tissue histology was performed to evaluate hepatic injury and AIH. Cytokine levels in serum and hepatic tissue were measured by enzyme-linked immunoassay (ELISA) and used quantitative polymerase chain reaction (qPCR). Levels of phosphorylated acetyl coenzyme-A carboxylase (ACC), representing AMPK activation, were detected by Western blotting.

Results

Serum ALT and AST levels were significantly reduced by berberine (100 and 200 mg/kg/day) in mice with Con A-induced hepatitis. Berberine also reduced Con A-induced hepatocyte swelling, cell death, and infiltration of leukocytes. Serum levels of tumor necrosis factor (TNF)-alpha, interferon (IF)-gamma, interleukin (IL)-2, and IL-1beta were reduced by berberine pre-treatment; levels of serum IL-10, an anti-inflammatory cytokine, was elevated. These protective effects of berberine on Con-A-induced AIH were reversed by treatment with Compound C.

Conclusions

In a murine model of Con A-induced AIH, berberine treatment reduced hepatic injury via activation of the AMPK pathway. Further studies are recommended to determine the potential therapeutic role for berberine in AIH.

Overexpression of miR-130a-3p/301a-3p attenuates high glucose-induced MPC5 podocyte dysfunction through suppression of TNF-α signaling

Tumor necrosis factor (TNF)-α has been reported to be important in glomerulonephritis, which is closely associated with podocyte dysfunction and apoptosis. However, the precise mechanisms by which TNF-α expression are regulated remain unclear. The purpose of the present study was to investigate the role of microRNA (miR)-130a-3p/301a-3p in the post-transcriptional control of TNF-α expression and high glucose (HG)-induced podocyte dysfunction. Mice MPC5 podocytes were incubated with HG and transfected with miR-130a-3p/301a-3p mimics or inhibitors, reactive oxygen species (ROS) levels were measured by flow cytometry assay, and the mRNA and protein levels were assayed by using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The targeted genes were predicted by a bioinformatics algorithm and verified using a dual luciferase reporter assay. It was observed that miR-130a-3p/301a-3p was a novel regulator of TNF-α in mouse podocytes. miR-130a-3p/301a-3p mimics inhibited TNF-α 3'-untranslated region luciferase reporter activity, in addition to endogenous TNF-α protein expression. Furthermore, forced expression of miR-130a-3p or miR-301a-3p resulted in the downregulation of ROS and malondialdehyde (MDA) and the upregulation of superoxide dismutase (SOD) 1 in the presence of HG. Inhibition of TNF-α level prevented a remarkable reduction in SOD activity and a marked increase in ROS and MDA levels in HG-treated podocytes. Furthermore, TNF-α loss-of-function significantly reversed HG-induced podocyte apoptosis. These data demonstrated a novel up-stream role for miR-130a-3p/301a-3p in TNF-α-mediated podocyte dysfunction and apoptosis in the presence of HG.

Growth performance, innate immune responses and disease resistance of fingerling blunt snout bream, Megalobrama amblycephala adapted to different berberine-dietary feeding modes

A 8-week feeding trial was conducted to evaluate the effect of different berberine-dietary feeding modes on growth, non-specific immune responses and disease resistance of blunt snout bream, Megalobrama amblycephala. Fish (average initial weight 4.70 ± 0.02 g) were fed two fat levels (5% and 10%) diets in three berberine-feeding modes (supplementing 50 mg/kg berberine continuously, two-week or four-week intervals) with four replicates, respectively. Then, fish were challenged by Aeromonas hydrophila and mortality was recorded for the next 96 h after feeding trial. The results showed that different feeding modes of berberine significantly influenced growth, innate immunity and antioxidant capability of fish. Fish fed normal diet with 50 mg/kg berberine at two-week interval mode reflected remarkably (P < 0.05) high weight gain (WG). Plasma TC and TG contents were significantly (P < 0.05) decreased. The lysozyme (LYZ) activities, complement component 3 (C3) and complement component 4 (C4) concentrations were significantly (P < 0.05) increased. Fish not only exhibited relatively low hepatopancreas malondialdehyde (MDA) and lipid peroxide (LPO) contents, but also significantly (P < 0.05) improved superoxide dismutase (SOD) and catalase (CAT) activities. Fish mortality after challenged by Aeromonas hydrophila was decreased. Same results were also presented in fish fed high-fat diet with 50 mg/kg berberine at two-week, four-week intervals or continuous feeding modes. Based on fish healthy improvement and feeding cost saving, blunt snout bream fed normal diet with 50 mg/kg berberine at two-week interval or fed high-fat diet with berberine at two-week or four-week intervals were optimal feeding mode, respectively.

Apelin involved in progression of diabetic nephropathy by inhibiting autophagy in podocytes

Podocyte autophagy dysfunction has been reported to be responsible for the progression of diabetic nephropathy (DN), however, the factors contributed to autophagy dysfunction in type 2 diabetes are not fully understood. Among promoting factors in DN, an adipokine, apelin, had been showed to trigger podocyte dysfunction. Therefore, it is hypothesized that apelin, which is increased in plasma in type 2 diabetes, lead to podocyte apoptosis through inhibiting podocyte autophagy, which resulted in podocyte dysfunction followed by DN. KkAy mice (diabetic mice) and cultured podocytes (MPC5 cells and native podocytes) were treated with high glucose (HG) and apelin or its antagonist F13A. Renal function, podocyte autophagy, podocyte apoptosis and corresponding cell signaling pathways in podocytes were detected. The results showed that apelin aggravated the renal dysfunction and foot process injuries in kkAy mice, which is positively correlated to podocyte apoptosis and negatively correlated to podocyte autophagy. Apelin induced podocyte apoptosis and inhibited podocyte autophagy in both normal glucose and HG conditions while F13A reversed these effects. Investigations by western blot found that apelin inhibits podocyte autophagy through ERK-, Akt- and mTOR-dependent pathways. In conclusion, increased apelin concentration in plasma inhibited podocyte autophagy, which would lead to podocyte apoptosis and renal dysfunction in diabetes. These effects would contribute to the progression of DN.

Podocyte Autophagy: A Potential Therapeutic Target to Prevent the Progression of Diabetic Nephropathy

Diabetic nephropathy (DN), a leading cause of end-stage renal disease (ESRD), becomes a worldwide problem. Ultrastructural changes of the glomerular filtration barrier, especially the pathological changes of podocytes, lead to proteinuria in patients with diabetes. Podocytes are major components of glomerular filtration barrier, lining outside of the glomerular basement membrane (GBM) to maintain the permeability of the GBM. Autophagy is a high conserved cellular process in lysosomes including impaired protein, cell organelles, and other contents in the cytoplasm. Recent studies suggest that activation of autophagy in podocytes may be a potential therapy to prevent the progression of DN. Here, we review the mechanisms of autophagy in podocytes and discuss the current studies about alleviating proteinuria via activating podocyte autophagy.