Glomerular Filtration Membrane Research Articles

Ultrasmall Polyphenol-NAD+ Nanoparticle-Mediated Renal Delivery for Mitochondrial Repair and Anti-Inflammatory Treatment of AKI-to-CKD Progression.

As a central metabolic molecule, nicotinamide adenine dinucleotide (NAD+) can potentially treat acute kidney injury (AKI) and chronic kidney disease (CKD); however, its bioavailability is poor due to short half-life, instability, the deficiency of targeting, and difficulties in transmembrane transport. Here a physiologically adaptive gallic acid-NAD+ nanoparticle is designed, which has ultrasmall size and pH-responsiveness, passes through the glomerular filtration membrane to reach injured renal tubules, and efficiently delivers NAD+ into the kidneys. With an effective accumulation in the kidneys, it restores renal function, immune microenvironment homeostasis, and mitochondrial homeostasis of AKI mice via the NAD+-Sirtuin-1 axis, and exerts strong antifibrotic effects on the AKI-to-CKD transition by inhibiting TGF-β signaling. It also exhibits excellent stability, biodegradable, and biocompatible properties, ensuring its long-term safety, practicality, and clinical translational feasibility. The present study shows a potential modality of mitochondrial repair and immunomodulation through nanoagents for the efficient and safe treatment of AKI and CKD.

Endoplasmic reticulum stress in diabetic kidney disease: adaptation and apoptosis after three UPR pathways.

Diabetes kidney disease (DKD) is one of the common chronic microvascular complications of diabetes, which has become the most important cause of modern chronic kidney disease beyond chronic glomerulonephritis. The endoplasmic reticulum is one of the largest organelles, and endoplasmic reticulum stress (ERS) is the basic mechanism of metabolic disorder in all organs and tissues. Under the stimulation of stress-induced factors, the endoplasmic reticulum, as a trophic receptor, regulates adaptive and apoptotic ERS through molecular chaperones and three unfolded protein reaction (UPR) pathways, thereby regulating diabetic renal damage. Therefore, three pathway factors have different expressions in different sections of renal tissues. This study deeply discussed the specific reagents, animals, cells, and clinical models related to ERS in DKD, and reviewed ERS-related three pathways on DKD with glomerular filtration membrane, renal tubular reabsorption, and other pathological lesions of different renal tissues, as well as the molecular biological mechanisms related to the balance of adaption and apoptosis by searching and sorting out MeSH subject words from PubMed database.

Effect and mechanism of Yupingfeng Powder on preventing recurrent respiratory tract infection in children with refractory nephrotic syndrome

Primary nephrotic syndrome in children is a group of clinical syndromes caused by the significant increase in the permeability of glomerular filtration membrane to plasma albumin and the loss of a large amount of albumin from urine due to various reasons. It is sensitive to hormones but easy to relapse, and may be dependent on hormones or resistant to drugs after repeated attacks, thus affecting the prognosis. Clinically, it is summarized as refractory nephrotic syndrome in children. Respiratory tract infection is one of the main factors causing the recurrence of refractory nephrotic syndrome in children. Yupingfeng Powder is the prescription of fuzheng Gubenjing, simple and effective, and it is widely used in clinic. Modern research confirmed that Yupingfeng can promote immunoglobulin IgA, IgG, IgE and monocyte macrophages, improve the immune function of the body, in recent years YuPingFeng alone or combined western medicine treatment of children repeated respiratory tract infection shows a unique curative effect and advantages, thus reducing the recurrence frequency of pediatric refractory nephrotic syndrome and frequency.

Store-operated Ca2+ channel signaling: Novel mechanism for podocyte injury in kidney disease.

Studies over the last decade have markedly broadened our understanding of store-operated Ca2+ channels (SOCs) and their roles in kidney diseases and podocyte dysfunction. Podocytes are terminally differentiated glomerular visceral epithelial cells which are tightly attached to the glomerular capillary basement membrane. Podocytes and their unique foot processes (pedicels) constitute the outer layer of the glomerular filtration membrane and the final barrier preventing filtration of albumin and other plasma proteins. Diabetic nephropathy and other renal diseases are associated with podocyte injury and proteinuria. Recent evidence demonstrates a pivotal role of store-operated Ca2+ entry (SOCE) in maintaining structural and functional integrity of podocytes. This article reviews the current knowledge of SOCE and its contributions to podocyte physiology. Recent studies of the contributions of SOC dysfunction to podocyte injury in both cell culture and animal models are discussed, including work in our laboratory. Several downstream signaling pathways mediating SOC function in podocytes also are examined. Understanding the pivotal roles of SOC in podocyte health and disease is essential, as SOCE-activated signaling pathways are potential treatment targets for podocyte injury-related kidney diseases.

Role of ion channels in the mechanism of proteinuria (Review).

Proteinuria is a common clinical manifestation of kidney diseases, such as glomerulonephritis, nephrotic syndrome, immunoglobulin A nephropathy and diabetic nephropathy. Therefore, proteinuria is considered to be a risk factor for renal dysfunction. Furthermore, proteinuria is also significantly associated with the progression of kidney diseases and increased mortality. Its occurrence is closely associated with damage to the structure of the glomerular filtration membrane. An impaired glomerular filtration membrane can affect the selective filtration function of the kidneys; therefore, several macromolecular substances, such as proteins, may pass through the filtration membrane and promote the manifestation of proteinuria. It has been reported that ion channels play a significant role in the mechanisms underlying proteinuria. Ion channel mutations or other dysfunctions have been implicated in several diseases, therefore ion channels could be used as major therapeutic targets. The mechanisms underlying the action of ion channels and ion transporters in proteinuria have been overlooked in the literature, despite their importance in identifying novel targets for treating proteinuria and delaying the progression of kidney diseases. The current review article focused on the four key ion channel groups, namely Na+, Ca2+, Cl- and K+ ion channels and the associated ion transporters.

Sirtuin Family and Diabetic Kidney Disease.

Diabetes mellitus (DM) is gradually attacking the health and life of people all over the world. Diabetic kidney disease (DKD) is one of the most common chronic microvascular complications of DM, whose mechanism is complex and still lacks research. Sirtuin family is a class III histone deacetylase with highly conserved NAD+ binding domain and catalytic functional domain, while different N-terminal and C-terminal structures enable them to bind different deacetylated substrates to participate in the cellular NAD+ metabolism. The kidney is an organ rich in NAD+ and database exploration of literature shows that the Sirtuin family has different expression localization in renal, cellular, and subcellular structures. With the progress of modern technology, a variety of animal models and reagents for the Sirtuin family and DKD emerged. Machine learning in the literature shows that the Sirtuin family can regulate pathophysiological injury mainly in the glomerular filtration membrane, renal tubular absorption, and immune inflammation through various mechanisms such as epigenetics, multiple signaling pathways, and mitochondrial function. These mechanisms are the key nodes participating in DKD. Thus, it is of great significance for target therapy to study biological functions of the Sirtuin family and DKD regulation mechanism in-depth.

A comprehensive insight into autophagy and its potential signaling pathways as a therapeutic target in podocyte injury.

As part of the glomerular filtration membrane, podocyte is terminally differentiated, structurally unique, and highly specialized in maintaining kidney function. Proteinuria caused by podocyte injury (foot process effacement) is the clinical symptom of various kidney diseases (CKD), including nephrotic syndrome. Podocyte autophagy has become a powerful therapeutic strategy target in ameliorating podocyte injury. Autophagy is known to be associated significantly with sirtuin-1, proteinuria, and podocyte injury. Various key findings in podocyte autophagy were reported in the past ten years, such as the role of endoplasmic reticulum (ER) stress in podocyte autophagy impairment, podocyte autophagy-related gene, essential roles of the signaling pathways: Mammalian Target of Rapamycin (mTOR)/ Phosphoinositide 3-kinase (PI3k)/ serine/threonine kinase 1 (Akt) in podocyte autophagy. These significant factors caused podocyte injury associated with autophagy impairment. Sirtuin-1 was reported to have a vital key role in mTOR signaling, 5'AMP-activated protein kinase (AMPK) regulation, autophagy activation, and various critical pathways associated with podocyte's function and health; it has potential value to podocyte injury pathogenesis investigation. From these findings, podocyte autophagy has become an attractive therapeutic strategy to ameliorate podocyte injury, and this review will provide an in-depth review on therapeutic targets he podocyte autophagy.

Detrimental effects of hypoxia on glomerular podocytes.

Hypoxia-inducible factor1 (HIF1) plays a pivotal role in ensuring cells adapt to low-oxygen conditions. Depletion of oxygen, a co-substrate during hydroxylation of prolyl (P402 and P564) residues of HIF1⍺, evades HIF1⍺ ubiquitination and enables its dimerization with HIF1β to mediate global transcriptional response to hypoxia. Though HIF1 is largely considered eliciting a protective role during physiological or pathological hypoxia or ischemia, elevated HIF1 during chronic hypoxia contributes to glomerular diseases' pathology and proteinuria. The glomerulus is responsible for renal permselectivity and excretion of ultra-filtrated urine. Podocytes are the glomerulus' major cell types and are instrumental for glomerular filtration, permselectivity, and glomerular basement membrane maintenance. Podocyte injury is expected to impair the efficiency of glomerular filtration and manifestation of glomerulosclerosis and proteinuria. Accumulated evidence suggests that podocytes are susceptible to various insults during chronic hypoxia, including podocyte EMT, slit-diaphragm dysfunction, foot process effacement, and cytoskeletal derangement due to accumulation of HIF1. This review discusses how hypoxia/HIF1 signaling regulates various features and function of podocytes during exposure to chronic hypoxia or inducing HIF1 by various chemical modulators.

Preparation of Gold Nanoparticles and Its Effect on Autophagy and Oxidative Stress in Chronic Kidney Disease Cell Model.

Gold nanoparticles (GNPs) are widely used in life sciences and medicine due to their simple preparation, stable physical and chemical properties, controllable optical properties and no significant toxicity. However, in recent years, studies have found that there are still many uncertain factors in the application of gold nanoparticles in the field of biomedicine, and there are few studies on the main excretion organs and kidneys of the body, especially the toxicological effects under the disease state have not been reported. Obviously, carrying out relevant research is of great significance for accelerating the clinical application of GNPs. Chronic kidney disease (CKD) is a group of chronic progressive diseases that have high prevalence and high mortality and are serious threats to human life and health. Renal tubular injury and interstitial fibrosis are key factors in renal dysfunction in chronic kidney disease. Drug and toxic kidney damage mostly involve renal tubular epithelial cells; hypoxia is the most common pathological condition of cells. In renal lesions, renal tubular epithelial cells often have hypoxia. Based on this, we propose the hypothesis of this study: glomerular filtration membrane damage in kidney disease, GNPs increase in urine, followed by reabsorption of renal tubular epithelial cells, thereby causing damage to the latter; if accompanied by hypoxia, GNPs it will aggravate renal tubular epithelial cell damage and promote tubulointerstitial fibrosis. In order to verify the above hypothesis, this study used a mouse model of adriamycin nephropathy and tubular epithelial cells and macrophages in vitro, and observed the damage of GNPs on renal tubular epithelial cells by various means, and explored related mechanisms. The results show that under normal oxygen conditions, GNPs can induce autophagy after cell entry, which can damage damaged proteins and organelles to maintain cell survival. In the absence of oxygen, nanoparticles entering cells increase and induce excessive autophagy. In the absence of oxygen, GNPs also aggregate in macrophages, which can cause decreased cell proliferation activity and induce activation of macrophage inflammasome, which induces inflammatory response: GNPs-induced secretion of hypoxic macrophages can be promoted.

Exogenous spermine attenuates diabetic kidney injury inrats by inhibiting AMPK/mTOR signaling pathway.

Diabetic nephropathy (DN) is the primary cause of end-stage renal disease, which is closely associated with dysfunction of the podocytes, the main component of the glomerular filtration membrane; however, the exact underlying mechanism is unknown. Polyamines, including spermine, spermidine and putrescine, have antioxidant and anti-aging properties that are involved in the progression of numerous diseases, but their role in DN has not yet been reported. The present study aimed to explore the role of polyamines in DN, particularly in podocyte injury, and to reveal the molecular mechanism underlying the protective effect of exogenous spermine. Streptozotocin intraperitoneal injection-induced type 1 diabetic (T1D) rat models and high glucose (HG)-stimulated podocyte injury models were established. It was found that in T1D rat kidneys and HG-induced podocytes, ornithine decarboxylase (a key enzyme for polyamine synthesis) was downregulated, while spermidine/spermine N1-acetyltransferase (a key enzyme for polyamines degradation) was upregulated, which suggested that reduction of the polyamine metabolic pool particularly decreased spermine content, is a major factor in DN progression. In addition, hyperglycemia can induce an increased rat kidney weight ratio, serum creatinine, urea, urinary albumin excretion and glomerular cell matrix levels, and promote mesangial thickening and loss or fusion of podocytes. The expression levels of podocyte marker proteins (nephrin, CD2-associated protein and podocin) and autophagy-related proteins [autophagy protein 5, microtube-associated proteins 1A/1B light chain 3 (LC3)II/LC3I, Beclin 1 and phosphorylated (p)-AMPK] were downregulated, while cleaved caspase-3, P62 and p-mTOR were increased. These changes could be improved by pretreatment with exogenous spermine or rapamycin (autophagic agonist). In conclusion, spermine may have the potential to prevent diabetic kidney injury in rats by promoting autophagy via regulating the AMPK/mTOR signaling pathway.

Progress in bio-inspired porous membranes

Porous membranes are one of the research hotspots in the domain of separation materials and have been widely utilized in various fields (such as water treatment, energy, biological medicine) due to their high separation efficiency, low cost, and non-secondary pollution, etc. However, there still exist many challenges in their application process, such as low selectivity, poor anti-fouling, poor responsive, critically limiting its development. Recently, bio-inspired porous membranes offer a brand-new idea for solving those problems and are becoming one of the most exciting research areas in porous membranes field. Compared with traditional porous membranes, bio-inspired porous membranes, designed by imitating the unique pore structure and separation performance of biological membranes, display distinct advantages in selectivity performance, antifouling property, intelligent gating property, and intelligent response property. This critical review detailedly presents the recent developments of bio-inspired porous membranes with multi-scale pore structure. In this paper, the first section mainly gives a brief introduction to the pore structure, separation selectivity, and response property of both nano-scale biological membranes and micro-scale biological membranes. Among numerous nano-scale biological membranes, the most concerning to date include cell membrane with ion channel, cell membrane with aquaporin, and glomerular filtration membrane. Ion channel embedded within cell membrane provides ion selectivity, ion current rectification, and ion gating characteristics to cell membrane. Inspired by this, novel porous membranes with excellent ion selectivity are developed for regulating ion permeation. Meanwhile, aquaporin can let the passive transport of water across cell membrane while simultaneously excluding ions, offering a new strategy for designing bio-inspired porous membrane for high efficiency desalination. Glomerular filtration membrane with the nano-scale pore can prevent the filtration of blood cells and platelets, and removes most of nano-scale molecules from the blood. Inspired by its unique filtration property, various bio-inspired porous membranes have been designed for clinical kidney replacement treatment. Additionally, the micro-scale porous membranes in nature mainly contain alveolar membrane with intelligent gating property and leaf stomata membrane with intelligent response property. By imitating the alveolar membrane, liquid gating porous membranes with intelligent gating property are developed, achieving for controlling the movement of fluids, vapours, and solids. Learning from leaf stomata membrane, intelligent responsive porous membranes are also designed, and can be applied in controllable transmission. For preparing the high performance of bio-inspired porous membranes, the designed strategies are also introduced in detail. The second section has further outlined the applications of bio-inspired porous membranes in water treatment, energy, biological medicine, and substance detection. In water treatment field, aquaporin-based bio-inspired porous membrane possesses better desalination performance than traditional porous membrane. In energy field, bio-inspired porous membranes offer unique ions selectivity and ions transport, thus enhancing energy conversion efficiency in salinity gradient energy capture. In biological medicine field, alveolar-like liquid gating composite membranes can be utilized for fabricating artificial blood vessel with anticoagulation and drug release properties. Moreover, bio-inspired porous membranes with porous support and thin separation layer are demonstrated as hemodialysis membranes for the treatment of kidney disease. In substance detection, visual and low power consuming chemical detection of specific analytes can be achieved by liquid gating composite membrane. In the last section, future challenges in theory, preparation technology, and application of bio-inspired porous membrane are presented, providing an overview of the various solutions. Ultimately, continued efforts to relative research and materials development will promote the rapid development of bio-inspired porous membrane.

Protective Effect of Angiotensin II Type 1-Receptor-Blocker on Diabetic Nephropathy in Rats: Role of Nephrin

Abstract Background: Angiotensin II-Receptor Blockers (ARBs) has a questionable nephroprotective effect especially in diabetic nephropathy. Nephrin protein molecules exist in the slit diaphragm of the glomerular filtration membrane and control the passage of plasma protein. Aim of Study: To examine the possible role of Nephrin in the pathogenesis of diabetic nephropathy and the protective effect of ATII-RB (candesartan) on diabetic nephropathy. Material and Methods: Thirty-two male rats were used in this experiment. Half of the rats were fed a high-fat diet (HFD) and the other half were fed a standard diet for 4 weeks. A model of diabetic nephropathy (DN) was created by a 35mg/kg intraperitoneal dose of Streptozotocin (STZ) in the HFD-fed rats. Then the rats were divided into four groups (8 rats/group). (1) Normal control (NC) group; (2) Diabetic nephropathy (DN) group; (3) ARB-treated NC group: Normal rats were treated with the ARB (Candesartan Cilexetil), in a dose 0.1mg/kg; (4) ARB-treated DN group: The rats with DN and received the above dose of candesartan for 4 weeks. The urine was collected to measure the urine flow rate, urinary concentrations of Nephrin, creatinine, and protein. Blood samples were used to measure urea, creatinine, glucose, insulin, and the homeostatic model assessment (HOMA-IR). Then renal tissue samples were used to measure Superoxide dismutase (SOD) activity and Malondialdehyde (MDA) in addition to histopathological examination. The mean arterial blood pressure (MABP) was also recorded. Results: Candesartan treatment in the DN group showed significant reductions of glucose, HOMA-IR, amelioration of renal antioxidant system, reductions in creatinine, reduction of proteinuria, reduction of urinary Nephrin, and MABP. Histological improvement was also detected in the form of mild glomerulosclerosis and interstitial fibrosis. The urinary Nephrin was 90 times high in the condition of DN. This huge rise of urinary Nephrin was significantly reduced by Cande-sartan treatment. Moreover, in the DN group the urinary Nephrin level showed a significant correlation with glucose level, serum creatinine, urinary protein-creatinine ratio, and MABP.Conclusion: ATII-RB could reduce urinary Nephrin ex-cretion and possibly alters its expression through its inhibitory effect on the reactive oxygen species, the Renin-Angiotensin-Aldosterone system and subsequently maintains the normal physiological activity of podocytes in rats with STZ-induced diabetic nephropathy.

Sleeve Gastrectomy Attenuates Diabetic Nephropathy by Upregulating Nephrin Expressions in Diabetic Obese Rats.

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, and sleeve gastrectomy (SG) is considered to be an effective strategy to improve pre-existing DN. However, the mechanism remains unknown. Animal model of DN was induced by high-fat diet (HFD) and streptozotocin (STZ). SG or sham surgery was performed and rats were sacrificed at 4, 8, and 12weeks after surgery. The basic parameters (blood glucose, body weight, kidney weight), indicators of renal function including serum creatinine (Scr), blood urea nitrogen (BUN), urine microalbumin, urine creatinine (Ucr), microalbumin creatinine ratio (UACR), ultrastructural changes of glomerulus, and the expression of nephrin gene and protein in glomerular podocytes were compared among groups. Blood glucose and body weight of SG rats were significantly lower than those of the sham-operated rats, and renal function of SG groups were also significantly improved within the postoperative period of 12weeks. The results of periodic acid-Schiff staining (PAS) and transmission electron microscopy (TEM) showed that glomerular hypertrophy and accumulation of extracellular matrix proteins were significantly alleviated after SG, and the thickness of basement membrane and the fusion or effacement of foot processes were also significantly improved. The mRNA and protein expression of nephrin in SG groups was significantly higher than that in the sham group. These results suggest that SG attenuates DN by upregulating the expression of nephrin and improving the ultrastructure of glomerular filtration membrane. This study indicates that SG can be used as an available therapeutic intervention for DN.

Glomerulopatías

The term glomerulopathy, also known as glomerulonephritis, defines a group of disorders characterized by the impairment of glomerular filtration membrane appearing, cellular components and macromolecules in urine and accompanied by variable deterioration of purifying function of kidney. It encompasses an heterogeneous group of nosological entities, showing quite common clinical patterns, highlighting among them nephritic and nephrotic syndrome, recurrent macroscopic hematuria and changes in urinary sediment. Although glomerular filtration rate can be normal, in many cases renal insufficiency with a variable temporal course develops. Pathological studies have developed a key role in their operative classification, allowing both the clinical course typing as well as to define their prognosis and treatment.

Oestrogen inhibits PTPRO to prevent the apoptosis of renal podocytes.

Podocytes are a major component of the glomerular filtration membrane, and their apoptosis is involved in a variety of nephrotic syndromes. In the current study, the effects and molecular mechanisms of oestrogen on the proliferation and apoptosis of podocytes were investigated to elucidate the role of oestrogen in the pathogenesis of childhood nephrotic syndrome. The cell proliferation of mouse renal podocytes (MPC-5) and human primary renal podocytes was promoted by 17β-oestradiol (E2) in what appear to be a time-dependent manner. Apoptosis was inhibited by E2 and promoted by the E2 antagonist, tamoxifen. The expression of protein tyrosine phosphatase receptor type O (PTPRO) decreased with the increasing dosage of E2, but increased with the increasing dosage tamoxifen in MPC-5 and human podocytes. The protein, oestrogen receptor (ER)α, was not expressed in MPC-5 and human podocytes. E2 binding to ERβ completely eliminated PTPRO expression in MPC-5. In podocytes, PTPRO was phosphorylated by E2 at the Y1007 and associated with tyrosine-protein kinase JAK2 (JAK2) activation, rather than JAK1 activation. PTPRO was involved in the binding of E2 to signal transducer and activator of transcription (STAT)3 at the Y705 and S727 sites, resulting in the phosphorylation of STAT3 in podocytes. Through PTPRO, E2 also regulated the proliferation and apoptosis of podocytes. In conclusion, oestrogen binding to ERβ, rather than ERα, promoted the proliferation of podocytes and inhibited the apoptosis of podocytes by inhibiting the expression of PTPRO. The mechanism may be associated with the activation of the JAK2/STAT3 signalling pathway. The current study may provide a novel direction for the treatment of childhood nephrotic syndrome.

Kidney-targeted rhein-loaded liponanoparticles for diabetic nephropathy therapy via size control and enhancement of renal cellular uptake.

The optimization of nanoparticle size for passing through glomerular filtration membrane, inefficient renal cellular uptake and rapid urinary excretion of nanoparticles are the major obstacles for renal disease treatment via a nanoparticle delivery system. Herein, we propose a concept of a two-step nanoparticular cascade of size control and enhancement of renal cellular uptake to overcome the renal delivery obstacles.Methods: We prepared kidney-targeted rhein (RH)-loaded liponanoparticles (KLPPR) with a yolk-shell structure composed by polycaprolactone-polyethyleneimine (PCL-PEI)-based cores and kidney targeting peptide (KTP)-modified lipid layers. The KLPPR size within the range of 30 ~ 80 nm allowed KLPPR distribute into kidney by passing through the glomerular filtration membrane and the KTP (sequence: CSAVPLC) decoration promoted the renal cellular uptake and endocytosis via a non-lysosomal pathway.Results: The KLPPR had an average size of 59.5±6.2 nm and exhibited high RH loading, sustained release, good stability and biocompatibility, rapid cellular uptake in HK-2 cells. In addition, intravenous administration of KLPPR resulted in excellent kidney-targeted distribution and low urinary excretion in mice with streptozocin-induced diabetic nephropathy (DN), lowered the parameters of urea nitrogen, serum creatinine and kidney index, as well as facilitated the recovery of renal physiological function in improving the levels of urinary creatinine and the creatinine clearance rate by suppressing secretion and accumulation of fibronectin and TGF-β1.Conclusion: Definitely, KLPPR were able to target the diseased kidney and improve the therapeutic effect of RH on DN by exploiting the two-step nanoparticular cascade of size control and enhancement of cellular uptake. This study offers a promising strategy for renal diseases treatment using liponanoparticle delivery system.

Kidney Response to Heart Failure: Proteomic Analysis of Cardiorenal Syndrome

Background/Aims: Chronic heart failure (HF) disrupts normal kidney function and leads to cardiorenal syndrome that further promotes HF progression. To identify potential participants in HF-related injury, we analyzed kidney proteome in an established HF model. Methods: HF was induced by chronic volume overload in male HanSD rats using aorto-caval fistula. After 21 weeks, cardiac and renal functions (in-situ kidney study) and renal proteomics were studied in sham-operated (controls) and HF rats, using iTRAQ labeling and LC-MS with Orbitrap Fusion, leading to identification and quantification of almost 4000 proteins. Results: Compared to controls, HF rats had cardiac hypertrophy, systemic and pulmonary congestion. Kidneys of HF rats had reduced renal blood flow, sodium excretion and urine production. While glomerular filtration rate, serum cystatin C and creatinine were still normal compared to controls, HF kidneys showed albuminuria and markedly increased tissue angiotensin-II levels (5-fold). HF kidneys (versus controls) displayed differential expression (˃1.5-fold) of 67 proteins. The most upregulated were angiotensin-converting enzyme (ACE, ˃20-fold), advanced glycosylation product-specific receptor (RAGE, 14-fold), periostin (6.8-fold), caveolin-1 (4.5-fold) and other proteins implicated in endothelial function (vWF, cavins 1-3, T-kininogen 2), proinflammatory ECM activation (MFAP4, collagen-VI, galectin-3, FHL-1, calponin) and proteins involved in glomerular filtration membrane integrity (CLIC5, ZO-1). Carboxylesterase-1D (CES1D), an enzyme that converts ACE inhibitors or sacubitril into active drugs, was also upregulated in HF kidneys. Conclusion: Chronic HF leads to latent kidney injury, associated with deep changes in kidney protein composition. These alterations may act in concert with intrarenal renin-angiotensin system activation and may serve as markers and/or targets to tackle cardiorenal syndrome.

Establishment of ApoE-knockout mouse model of preeclampsia and relevant mechanisms.

In the present study, we established an ApoE-knockout mouse model of preeclampsia to examine the role of vascular endothelial injury associated with abnormal lipid metabolism in the pathogenesis of preeclampsia. To establish the ApoE-knockout homozygous (ApoE−/−) and heterozygous (ApoE+/−) mouse model, mice were mated with the same genotype and orbital blood on day 19 of conception was collected. The progeny mice were assigned into 3 groups: ApoE−/, ApoE+/− and wild-type (WT) groups. Total cholesterol, triglyceride, low-density and high-density lipoprotein were measured in the serum at the end of conception. During conception, the systolic blood pressure of caudal artery was measured every 4 days. Using bicinchoninic acid protein assay, urinary protein and creatinine ratio was measured with a creatinine kit. We observed the pathological changes of glomerular filtration membrane and macroscopic/microscopic morphological changes of placenta by hematoxylin and eosin (H&E) staining and transmission electron microscope. Take fetal mouse through cesarean section on 19th day, measure the birth weight and placental weight of fetal mouse. Using ELISA we measured the expression levels of toll-like receptor 4 (TLR4) and soluble fms-like tyrosine kinase-1 (sFlt-1). Our results showed that the differences in serum lipid levels were not statistically significant (P>0.05). The mean systolic blood pressure, urinary protein and creatinine in ApoE−/− group were significantly higher than ApoE+/− group and WT group (P<0.05). Thickening and edema of glomerular filtration membrane, capillary thrombosis, significant edema and necrosis of placental villous stroma were observed in ApoE−/− group. No significant change was detected in the ApoE+/− or WT group. The TLR4 and sFlt-1 expression levels in ApoE−/− group were significantly higher than ApoE+/− and WT group (P<0.05). We concluded that ApoE-knockout mouse could simulate the pathologic process of preeclampsia, while the changes in serum lipids were not noteworthy, thus the pathogenesis of preeclampsia may be mediated by TLF4 and sFlt-1.

Dynamic change of glomerular filtration rate in the early stage is associated with kidney allograft status: a preliminary report.

BackgroundThis study aimed to investigate the relationship between the dynamic changes of estimated glomerular filtration rate (eGFR) in the early stage post renal transplantation and renal allograft dysfunction.MethodsWe selected 9 patients with interstitial fibrosis and tubular atrophy (IF/TA) and 11 patients with stable renal function based on the Banff 2007 classification system. Pathology of the patients was evidenced with renal biopsy results. Glomerular filtration rate (GFR) was calculated continuously for 14 days post-transplantation by using an estimated GFR (eGFR) formula adjusted into Chinese. Linear regression was employed, and eGFR slopes were compared. Prisoners or organs from prisoners were not used in this study.Results and ConclusionThe eGFR slope in the IF/TA group was significantly higher than that in the stable group (P < 0.01), and a cut-off value of 5.11 mL/min/1.73 m2/d was a reliable clinical value in a receiver operating characteristic (ROC) curve. On the basis of the ROC area under the curve, predictive accuracy of the eGFR slope was excellent (0.848). In conclusion, the eGFR in IF/TA increased faster within a period of 14 days post-transplantation, suggesting that reperfusion in the early stage may damage the glomerular filtration membrane to some extent. Furthermore, reperfusion might adversely affect long-term renal allograft survival.

Grape seed proanthocyanidin extracts ameliorate podocyte injury by activating peroxisome proliferator-activated receptor-γ coactivator 1α in low-dose streptozotocin-and high-carbohydrate/high-fat diet-induced diabetic rats.

Podocytes are part of the glomerular filtration membrane in kidney and serve to prevent the filtration of protein from the blood. Several evidences suggest that mitochondrial dysfunction plays a critical role in the pathogenesis of diabetic nephropathy and it is an early event in podocyte injury. Mitochondrial dysfunction promotes oxidative stress that can favor the development of podocyte injury. Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) was considered to be a major regulator of metabolic homeostasis and mitochondrial function. Some studies indicated that polyphenols may improve mitochondrial dysfunction, maintain the podocyte integrity and have therapeutic effects on glomerular diseases by promoting PGC-1α expression. Our study investigated whether grape seed proanthocyanidin extracts (GSPE), a strong antioxidant, ameliorate podocyte injury by activating PGC-1α in low-dose streptozotocin-and high-carbohydrate/high-fat diet-induced diabetic rats. After 16 weeks of GSPE treatment, GSPE slightly increased the body weight and decreased plasma glucose, food intake, water intake and urine volume in diabetic rats. Further, GSPE significantly decreased 24 h albumin levels and increased the expression of nephrin and podocalyxin. The antioxidant levels were improved and the cellular damage of kidney in diabetic rats was also relieved effectively after the treatment. Moreover, GSPE increased the mRNA expression of mitochondrial biogenesis factors and mitochondrial DNA content. Finally, GSPE activated the expression of PGC-1α, silent mating type information regulation 2 homolog 1 (SIRT1) and AMP-activated protein kinase (AMPK). These results suggest that GSPE ameliorate podocyte injury in diabetic nephropathy by the activation of AMPK-SIRT1-PGC-1α signalling, which appears to inhibit oxidative stress and mitochondrial dysfunction in the kidney.