Damage Glomeruli Research Articles

Roles of Mitochondrial Dysfunction in Diabetic Kidney Disease: New Perspectives from Mechanism to Therapy.

Diabetic kidney disease (DKD) is a common microvascular complication of diabetes and the main cause of end-stage renal disease around the world. Mitochondria are the main organelles responsible for producing energy in cells and are closely involved in maintaining normal organ function. Studies have found that a high-sugar environment can damage glomeruli and tubules and trigger mitochondrial dysfunction. Meanwhile, animal experiments have shown that DKD symptoms are alleviated when mitochondrial damage is targeted, suggesting that mitochondrial dysfunction is inextricably linked to the development of DKD. This article describes the mechanisms of mitochondrial dysfunction and the progression and onset of DKD. The relationship between DKD and mitochondrial dysfunction is discussed. At the same time, the progress of DKD treatment targeting mitochondrial dysfunction is summarized. We hope to provide new insights into the progress and treatment of DKD.

#1978 Proteomic analysis of exosomes derived from mesangial cells treated with galactose-deficient IgA1

Abstract Background and Aims IgA nephropathy (IgAN) is an autoimmune disease characterized by IgA deposits that build up in the kidneys, inflame and damage glomeruli causing hematuria and proteinuria. It is a leading cause of chronic kidney disease, which often results in end-stage kidney disease. There is no disease specific treatment for IgAN. The glomerulus, in which IgA1 lacking galactose residues (gdIgA1) are deposited, consists of mesangial cells, podocytes, and endothelial cells. Crosstalk between the cell types allows the glomerulus to act as a unit and react to its dynamic environment. There is very little evidence on mesangial cell derived exosomes and their cargo to understand the pathological crosstalk signaling in the glomerulus of IgAN. We isolated exosomes from mesangial cells that were treated with patient-derived gdIgA1 and IgA1 complexes. Proteomic analysis was performed to identify the exosome cargo and delineate the signaling pathways leading to maladaptive paracrine crosstalk. From our study, we aim to understand the molecular targets for therapeutic strategies in IgAN. Method Human mesangial cells were treated with/without IgA1, gdIgA1 or IgG for 24 h. Cell culture supernatant was collected for exosome isolations. Exosomes were analyzed by size, morphology and number using TEM and NanoFCM. Exosome protein extracts were processed for LC-Tandem mass spectrometry analysis using filter-aided sample preparation protocol. Proteomic analysis was performed using Qlucore omics explorer and pathway analysis using Ingenuity Pathway Analysis (IPA). Exosome marker expressions such as CD63, CD81 and FLOT1 and proteome validation was performed using Western blotting. Statistical analysis was performed using GraphPad Prism and values <0.05 were considered significant. Results We confirmed the release of exosomes by mesangial cells in response to IgA1/gdIgA1 complexes. Exosomes were fewer in unstimulated cells as compared to IgA1/gdIgA1 treated cells. They showed round morphology with a dense core and uniform size distribution. Exosomes from treated cells showed a mean size of about 75 nm and concentration in the range of 1-2 × 10^10 particles/ml. While untreated cells showed a mean size of about 100 nm and concentration of about 1 × 10^9 particles/ml. We confirmed the protein expression of exosome markers such as CD63, CD81 and FLOT1. For the first time, we demonstrated global proteomics on exosomes from mesangial cells followed by pathway analysis. We have identified 89 unique proteins and pathways in exosomes derived from gdIgA1 treated mesangial cells that could mediate pathological signaling in the glomerulus in comparison to exosomes derived from IgA1 treated mesangial cells. Conclusion Our study provides an understanding of the pathological crosstalk signaling through exosomes and key molecular targets for IgAN.

Assessment of palmitic acid toxicity to animal hearts and other major organs based on acute toxicity, network pharmacology, and molecular docking

Palmitic acid is a common ingredient in many foods and traditional Chinese medicines. However, modern pharmacological experiments have shown that palmitic acid has toxic side effects. It can damage glomeruli, cardiomyocytes, and hepatocytes, as well as promote the growth of lung cancer cells. Despite this, there are few reports evaluating the safety of palmitic acid through animal experiments, and the mechanism of palmitic acid toxicity remains unclear. Clarifying the adverse reactions and mechanisms of palmitic acid in animal hearts and other major organs is of great significance for ensuring the safety of clinical application. Therefore, this study records an acute toxicity experiment on palmitic acid in a mouse model, and the observation of pathological changes in the heart, liver, lungs, and kidneys. It is found that palmitic acid had toxic and side effects on animal heart. Then the key targets of palmitic acid in regulating cardiac toxicity were screened using network pharmacology, and a “component-target-cardiotoxicity” network diagram and PPI network were constructed. The mechanisms regulating cardiotoxicity were explored using KEGG signal pathway and GO biological process enrichment analyses. Molecular docking models were used for verification. The results showed that the maximum dose of palmitic acid had low toxicity in the hearts of mice. The mechanism of cardiotoxicity of palmitic acid involves multiple targets, biological processes, and signaling pathways. Palmitic acid can induce steatosis in hepatocytes, and regulate cancer cells. This study preliminarily evaluated the safety of palmitic acid and provided a scientific basis for its safe application.

Study the effect of obesity on the liver and kidney of the white rats embryos followed by using of grape seed oil to treat it. (morphological and histological study)

The present study was designed to identify the effect of obesity on liver and kidneys rats fetuses Rattus norvegicus and the ability of grape seeds oil to treat these effects.
 The present study used 12 female rat which divided randomly into three groups (each group containing four female) the first group was control group administrated only normal diet and water, the second group was fed a high fat diet for three months, the third groups fed a high fat diet for three months and treated with grape seed oil at a dose of 0.1 ml/ kg body weight. The results showed the effect of a high fat diet lead to inducing morphological changes in fetuses included decrease in the numbers and sizes of fetuses in the horns of uterus with shortness in the limbs. The histological lesions included necrosis, degenerative changes, in liver tissue with increased in sinusoids diameter. About kidneys, the lesions included desquamation of epithelium of some proximal convoluted tubules with damage of some of its, also damage glomeruli. After the treatment with grape seeds oil observed most of the embryos appeared normal in size and number without any lesions in the liver and kidney tissue of embryos.

Elevated Levels of Urinary Extracellular Vesicle Fibroblast-Specific Protein 1 in Patients with Active Crescentic Glomerulonephritis

Background/Aims: Extracellular vesicles (EVs), including exosomes, are present in various bodily fluids, including urine. We and others previously reported that cells expressing fibroblast-specific protein 1 (FSP1) accumulate within damaged glomeruli, and that urinary FSP1, as well as urinary soluble CD163, could potentially serve as a biomarker of ongoing glomerular injury. Methods: To test that idea, we collected urine samples from 37 patients with glomerular disease; purified the urinary EVs; characterized them using Nanosight, western blotting, and immunoelectron microscopy; and determined FSP1 and soluble CD163 levels using enzyme-linked immunosorbent assays. Results: Deemed to be mainly exosomes based on their size distribution, the EVs in urine contained FSP1, and a portion of the FSP1-positive vesicles was also positive for podocalyxin. FSP1 levels in urinary EVs were (1) positively correlated with rates of biopsy-proven cellular crescent formation (r = 0.562, p < 0.001) and total crescent formation (r = 0.448, p = 0.005) among total glomeruli; (2) significantly higher in patients with cellular crescents affecting 20% or more of their glomeruli than in those with fewer affected glomeruli (p = 0.003); and (3) significantly decreased after glucocorticoid and immunosuppressant therapy (p < 0.05). A positive correlation between FSP1 levels in urinary EVs and urinary soluble CD163 levels was confirmed (r = 0.367, p < 0.05). Conclusion: These data suggest that a portion of urinary FSP1 is secreted as EVs originating from podocytes, and that FSP1 levels reflect active and ongoing glomerular injury and disease activity, such as cellular crescent formation.

Potential benefits and harms of NADPH oxidase type 4 in the kidneys and cardiovascular system.

The main function of NADPH oxidases is to catalyse the formation of reactive oxygen species (ROS). NADPH oxidase 4 (NOX4) is expressed at high levels in kidney tubular cells, and at lower levels in endothelial cells, cardiomyocytes and other cell types under physiological conditions. NOX4 is constitutively active producing hydrogen peroxide (H2O2) as the prevalent ROS detected, whereas other NOX isoforms present in the renal and cardiovascular systems (i.e. NOX1, NOX2 and NOX5) generate superoxide radical anions as main products. Pharmacological inhibition of NOX4 has received enormous attention for its potential therapeutic benefit in fibrotic disease and nephropathologies. Ongoing clinical trials are testing this approach in humans. Diabetes elevates NOX4 expression in podocytes and mesangial cells, which was shown to damage glomeruli leading to podocyte loss, mesangial cell hypertrophy and matrix accumulation. Consequently, NOX4 represents an interesting therapeutic target in diabetic nephropathy. On the contrary, experiments using NOX4-deficient mice have shown that NOX4 is cytoprotective in tubular cells, cardiomyocytes, endothelial cells and vascular smooth muscle cells, and has a metabolism-regulating role when these cells are subjected to injury. Mice with systemic NOX4 deletion are more susceptible to acute and chronic tubular injury, heart failure and atherosclerosis. Overall, the current literature suggests a detrimental role of increased NOX4 expression in mesangial cells and podocytes during diabetic nephropathy, but a cytoprotective role of this enzyme in other cellular types where it is expressed endogenously. We review here the recent evidence on the role of NOX4 in the kidneys and cardiovascular system. With the emergence of pharmacological NOX4 inhibitors in clinical trials, caution should be taken in identifying potential side effects in patients prone to acute kidney injury and cardiovascular disease.

IgM exacerbates glomerular disease progression in complement-induced glomerulopathy

While glomerular IgM deposition occurs in a variety of glomerular diseases the mechanism of deposition and its clinical significance remain controversial. Some have theorized IgM becomes passively trapped in areas of glomerulosclerosis. However, recent studies found that IgM specifically binds damaged glomeruli. Therefore, we tested whether natural IgM binds to neo-epitopes exposed after insults to the glomerulus and exacerbate disease in mice deficient in the complement regulatory protein factor H; a model of non-sclerotic and nonimmune-complex glomerular disease. Immunofluorescence microscopy demonstrated mesangial and capillary loop deposition of IgM while ultrastructural analysis found IgM deposition on endothelial cells and subendothelial areas. Factor H deficient mice lacking B cells were protected from renal damage, as evidenced by milder histologic lesions on light and electron microscopy. IgM, but not IgG, from wild-type mice bound to cultured murine mesangial cells. Furthermore, injection of purified IgM into mice lacking B cells bound within the glomeruli and induced proteinuria. A monoclonal natural IgM recognizing phospholipids also bound to glomeruli in vivo and induced albuminuria. Thus, our results indicate specific IgM antibodies bind to glomerular epitopes and that IgM contributes to the progression of glomerular damage in this mouse model of non-sclerotic glomerular disease.

Failed Tubule Recovery, AKI-CKD Transition, and Kidney Disease Progression.

The transition of AKI to CKD has major clinical significance. As reviewed here, recent studies show that a subpopulation of dedifferentiated, proliferating tubules recovering from AKI undergo pathologic growth arrest, fail to redifferentiate, and become atrophic. These abnormal tubules exhibit persistent, unregulated, and progressively increasing profibrotic signaling along multiple pathways. Paracrine products derived therefrom perturb normal interactions between peritubular capillary endothelium and pericyte-like fibroblasts, leading to myofibroblast transformation, proliferation, and fibrosis as well as capillary disintegration and rarefaction. Although signals from injured endothelium and inflammatory/immune cells also contribute, tubule injury alone is sufficient to produce the interstitial pathology required for fibrosis. Localized hypoxia produced by microvascular pathology may also prevent tubule recovery. However, fibrosis is not intrinsically progressive, and microvascular pathology develops strictly around damaged tubules; thus, additional deterioration of kidney structure after the transition of AKI to CKD requires new acute injury or other mechanisms of progression. Indeed, experiments using an acute-on-chronic injury model suggest that additional loss of parenchyma caused by failed repair of AKI in kidneys with prior renal mass reduction triggers hemodynamically mediated processes that damage glomeruli to cause progression. Continued investigation of these pathologic mechanisms should reveal options for preventing renal disease progression after AKI.

Expression of ß‐carotene 15,15′‐monooxygenase gene and retinol status in rats with puromycin aminonucleoside‐induced nephrosis

Retinol and its metabolite retinoic acid play a critical role in immunity, reproduction, and development. Retinoids are known to influence renal development, and show beneficial effects in experimental models of renal disease. beta-Carotene (provitamin A) is cleaved to retinal by beta-carotene 15,15'- monooxygenase (BCM), which is an essential enzyme for retinoid biosynthesis. However, the metabolism of retinol and beta-carotene in renal diseases such as nephrosis remains unclear. We studied BCM gene expression and retinol status in rats with nephrotic syndrome induced by puromycin aminonucleoside (PAN). BCM gene expression in the liver and intestines of PAN-treated rats was decreased compared with that in controls, while the expression in the kidney of PAN-treated animals was increased. Plasma retinol and retinol-binding protein levels were decreased in PAN-treated rats, but hepatic retinol level did not differ between PAN-treated and control rats. Up-regulation of BCM gene expression in the kidneys of rats with nephrotic syndrome may result in increased conversion of beta-carotene to retinal, so this change might supply more retinoic acid to the damaged glomeruli. Changes in the metabolism of retinol and beta-carotene might have an important role in protection against the development of nephrosis.

Comparison of L-type and mixed L- and T-type calcium channel blockers on kidney injury caused by deoxycorticosterone-salt hypertension in rats

The efficiency of calcium channel blockers (CCBs) in the treatment of chronic renal disease (CRD) is controversial. In this study, we investigated whether combined T- and L-type CCBs, using mibefradil (30 mg/kg/d), provided superior protection versus traditional L-type voltage-gated CCBs, using amlodipine (10 mg/kg/d), in the deoxycorticosterone acetate (DOCA)-salt model of high glomerular blood pressure (PGC) and rapidly developing kidney damage. After 4 to 5 weeks of DOCA-salt, amlodipine did not reduce proteinuria (protein, 341 ± 90 versus 482 ± 54 mg/24 h; P = not significant) or degree of glomerular damage (20% ± 4% versus 28% ± 6% damaged glomeruli; P = not significant) compared with untreated rats. Conversely, mibefradil reduced proteinuria and glomerular damage versus untreated DOCA-salt rats (protein, 244 ± 75 mg/24 h; P < 0.02; damaged glomeruli, 11% ± 3%; P < 0.05). Both CCBs had similar antihypertensive actions, returning blood pressure to the untreated sham value. Of note, PGC also was reduced by a similar extent (and to the sham value) with both mibefradil (58 ± 2 mm Hg; P < 0.001) and amlodipine (61 ± 2 mm Hg; P < 0.005) versus untreated DOCA-salt rats (70 ± 1 mm Hg). This study shows that combined T- and L-type CCBs provide superior protection against CRD in the DOCA-salt model compared with L-type CCBs alone. However, this protection was not hemodynamic because similar systemic and glomerular antihypertensive responses occurred with both mibefradil and amlodipine. Although mibefradil was withdrawn from the market because of adverse drug interactions not associated with CCBs, other mixed channel blockers may provide an alternative or adjunctive therapy to angiotensin-converting enzyme inhibition in CRD. © 2001 by the National Kidney Foundation, Inc.

Hypertensive renal damage: Modulation expression of smooth muscle myosin heavy chain isoforms

Summary: The aim of this study was to determine the phenotypic modulation in preglomerular vascular smooth muscles and glomerular cells in hypertension. Eight‐week‐old stroke‐prone spontaneously hypertensive rats (SHRSP) fed high sodium pellets (3%) were untreated or treated with a calcium antagonist, manidipine HCI (2 mg/kg per day), for 8 weeks. the expression of myosin heavy chain isoforms (MHC), SM2 (muscletype) and SMemb (non‐muscle‐type) or α‐actin was examined by the immunohistochemical technique. In normotensive Wistar‐Kyoto rats, both SM2 and α‐actin were expressed equally in the smooth muscles of preglomerular vessels, and SMemb was expressed slightly in the glomerular epithelial cells. In the SHRSP, however, the expression of SM2 and α‐actin was significantly decreased or disappeared in the afferent arterioles, depending on the degree of vascular damage. In damaged glomeruli, SMemb and α‐actin were newly expressed in mesangial cells. Manidipine HCI attenuated the renal damage and restored the expression of α‐actin in the afferent arterioles. There was a significant correlation between the glomerular damage and the attenuation of SM2 expression (r=0.87). In conclusion, phenotypic modulation of vascular smooth muscles occurred in hypertensive renal damage and was correlated with the glomerular damage, where the phenotypic modulation also took place in the mesangial cells. These results indicate that the phenotypic modulations revealed by the expression of myosin isoforms might play an important role in the development of hypertensive renal damage.

Tumor necrosis factor-α augments the pro-inflammatory interaction between PMN and GBM via a CD 18 dependent mechanism

Acute glomerulonephritis is frequently associated with intraglomerular neutrophil (PMN) accumulation and the intensity of the inflammatory reaction is correlated with elevated concentrations of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF alpha). PMN are thought to damage glomeruli due to a combination of reactive oxygen species and proteolytic enzymes. Using an in vitro model of anti-GBM nephritis the effects of TNF alpha on GBM damage by PMN were evaluated. The interaction of GBM and PMN resulted in a low grade respiratory burst that was significantly augmented by the addition of TNF alpha. Luminol dependent chemiluminescence (LCL) was increased from 2.4 x 10(6) to 48.1 x 10(6) (P < 0.05). The GBM induced LCL could be > 85% inhibited by blocking with monoclonal antibodies (mAbs) to the common beta chain of the PMN beta 2 integrin family (CD18), but was unaffected by mAbs to CD11a or CD11b subunits. Degradation of GBM, however, was not influenced by either TNF alpha priming of PMN or anti-beta 2 integrin mAbs. When PMN were incubated with GBM-anti-GBM IgG complex they underwent an increase in LCL from 2.4 x 10(6) to 31.1 x 10(6). They also degraded more GBM than controls (10.1% vs. 1.8%). These aspects of PMN activation were Fc receptor mediated, dependent upon anti-GBM IgG being bound to GBM and inhibited by mAb to the PMN Fc receptor. These studies show that TNF alpha can modulate the inflammatory response of PMN in contact with GBM in a CD18 dependent manner. In contrast, Fc receptor mediated events are uninfluenced by TNF alpha.