Pathogenesis Of Nephropathy Research Articles

Research progress of IgA nephropathy markers

IgA nephropathy is one of the most common forms of primary glomerulonephritis, and its clinical presentation and prognosis vary greatly among individuals, so early identification of individuals at high risk of poor prognosis is crucial. Currently, the clinical predictors of IgAN include hypertension, proteinuria, glomerular filtration rate and Oxford pathological staging, which are non-specific, invasive and delayed. With further research into the pathogenesis of IgAN, some new, simpler and earlier biomarkers have been identified. In this paper, the role of cytokine, protein and nucleic acid markers in the diagnosis of IgA nephropathy is described in a comprehensive manner based on the pathogenesis of IgA nephropathy. It is expected that based on the pathogenesis of IgA nephropathy, more markers of IgA nephropathy will be discovered by studying the four-fold strike doctrine and other related doctrines to help detect subclinical disease activity, monitor disease progression and assess treatment.

Clopidogrel delays and can reverse diabetic nephropathy pathogenesis in type 2 diabetic db/db mice.

BACKGROUNDDiabetic nephropathy (DN) is the principal cause of end-stage renal disease. Previous studies have shown that clopidogrel can prevent the early progression of renal injury.AIMTo elucidate whether clopidogrel is beneficial against DN by using a db/db mouse model.METHODS db/db mice with a higher urinary albumin/creatinine ratio (ACR) relative to age- and sex-matched wild-type control mice were randomly allocated to clopidogrel and vehicle treatment groups. Clopidogrel was administered at doses of 5, 10, and 20 mg/kg by gavage for 12 wk. Body mass, blood glucose level, and urinary creatinine and albumin concentrations in each group were measured before and after the intervention. Renal fibrosis was evaluated using periodic acid-Schiff and Masson’s trichrome staining. The renal protein expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and F4/80 was assessed using immunohistochemistry. Urinary TNF-α, monocyte chemoattractant protein-1 (MCP-1), and IL-6 levels were analyzed using enzyme-linked immunosorbent assay; TNF-α and IL-1β mRNA expression was measured using real-time quantitative polymerase chain reaction. The protein expression of fibronectin (FN) and collagen I was assessed using immunohistochemistry.RESULTSClopidogrel treatment did not affect the body mass or blood glucose level of the db/db mice; however, it increased bleeding time and reduced urinary ACR in a dose-dependent manner. Immunohistochemical staining revealed an amelioration of renal fibrosis, significantly lower deposition of FN and collagen I, and significantly lower expression of the proinflammatory cytokines TNF-α and IL-1β and lower levels of urinary TNF-α and MCP-1 in the clopidogrel-treated db/db mice (P < 0.05). Furthermore, clopidogrel significantly reduced macrophage infiltration into the glomeruli of the db/db mice.CONCLUSIONClopidogrel significantly reduced renal collagen deposition and fibrosis and prevented renal dysfunction in db/db mice, most likely through inhibition of renal macrophage infiltration and the associated inflammation.

A Discussion on TCM Treatment and the Pathogenesis of Membranous Nephropathy in Primary Nephrotic Syndrome

Objective: To investigate the TCM treatment principle of membranous nephropathy and its effect. Methods: A total of 56 patients were selected from the Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine. They were then divided into the control group (western medicine standard therapy) and the study group (Qidi Gushen prescription), with 28 patients in each group. The treatment effect, treatment safety, and patients’ satisfaction were observed and compared between the two groups. Results: The results showed that the treatment effect of the study group was 96.43%, which was significantly better compared with the control group (75.00%) (p &lt; 0.05); in terms of safety, the probability of adverse events was 7.14% in the study group and 32.14% in the control group, in which the difference was statistically significant (p &lt; 0.05); in addition, the study group’s satisfaction with the treatment measures was significantly higher than that of the control group (p &lt; 0.05). Conclusion: In treating membranous nephropathy, traditional Chinese medicine can be tailored to its pathogenesis, which is not only beneficial to the treatment effect, but also has a high safety profile.

Interleukin-6 Downregulates the Expression of Vascular Endothelial-Cadherin and Increases Permeability in Renal Glomerular Endothelial Cells via the Trans-Signaling Pathway

The pathogenesis of IgA nephropathy (IgAN) is still unknown, but reportedly, interleukin 6 (IL-6) is involved in this process. However, its role in damaging glomerular endothelial cells is still unclear. Therefore, in this study, to clarify the mechanism of the pathogenesis of IgAN, we investigated the effect of IL-6 on the permeability of glomerular endothelial cells. A rat model of IgAN was established, and the animals divided into two groups, namely, the normal and IgAN groups. Glomerular endothelial cell injury was evaluated via electron microscopy. Furthermore, IL-6-induced changes in the permeability of human renal glomerular endothelial cells (HRGECs) were measured via trans-endothelial resistance (TEER) measurements and fluorescein isothiocyanate-dextran fluorescence. Furthermore, vascular endothelial-cadherin (VE-cadherin) was overexpressed to clarify the effect of IL-6 on HRGEC permeability, and to determine the pathway by which it acts. The classical signaling pathway was blocked by silencing IL-6R and the trans-signaling pathway was blocked by sgp30Fc. In IgAN rats, electron microscopy showed glomerular endothelial cell damage and western blotting revealed a significant increase in IL-6 expression, while VE-cadherin expression decreased significantly in the renal tissues. IL-6/IL-6R stimulation also significantly increased the permeability of HRGECs (p < 0.05). This effect was significantly reduced by VE-cadherin overexpression (p < 0.01). After IL-6R was silenced, IL-6/IL-6R still significantly reduced VE-cadherin expression and sgp30Fc blocked the trans-signaling pathway as well as the upregulation of IL-6/IL-6R-induced VE-cadherin expression. This suggests that IL-6 mainly acts via the trans-signaling pathway. IL-6 increased the permeability of HRGECs by decreasing the expression of VE-cadherin via the trans-signaling pathway.

Correlation between IgAC3 ratio and oxford score in IgA nephropathy.

Complement activation has an important role in the pathogenesis of IgA nephropathy. To determine the correlation between IgAC3 ratio (IgA/C3) and total Oxford score and predictive value of IgA/C3 in IgA nephropathy. Methods Forty-three patients diagnosed with IgA nephropathy with > 10 glomerular + 1 arteries in biopsy were included in the study. Hematological and biochemical variables of the blood sample taken before the biopsy and total Oxford score were recorded. The study group was divided into two groups as proteinuria ≥ 1g (PU ≥ 1) and proteinuria < 1g (PU < 1). Statistics were carried out with SPSS 22.0 program. p < .05 considered as significant. The mean age of 43 patients was 40.4 (± 11.9) years; 51.2% of them were women. Proteinuria as 1g or more was in 27 of 43 patients, and less than 1g in 16 patients. The serum C3 level was lower in the group with PU ≥ 1 and showed a significant positive correlation with the IgA/C3 total Oxford score. A significant correlation was found between serum IgA/C3 and total Oxford score.

Hepatocyte nuclear factors play an important role in the pathogenesis of nephropathy

Hepatocyte nuclear factors play an important role in the pathogenesis of nephropathy

Gut Microbes in Immunoglobulin A Nephropathy and Their Potential Therapeutic Applications.

Microbial ecosystem consists of a complex community of bacterial interactions and its host microenvironment (tissue, cell, metabolite). Because the interaction between gut microbiota and host involves many diseases and seriously affects human health, the study of the interaction mechanism between gut microbiota and host has attracted great attention. The gut microbiome is made up of 100 trillion bacteria that have both beneficial and adverse effects on human health. The development of IgA Nephropathy results in changes in the intestinal microbial ecosystem that affect host physiology and health. Similarly, changes in intestinal microbiota also affect the development of IgA Nephropathy. Thus, the gut microbiome represents a novel therapeutic target for improving the outcome of IgA Nephropathy, including hematuria symptoms and disease progression. In this review, we summarize the effect of intestinal microbiota on IgA Nephropathy in recent years and it has been clarified that the intestinal microbiota has a great influence on the pathogenesis and treatment of IgA Nephropathy.

FC049: Nefecon® (Budesonide) is an Epigenetic Modifier in IGA Nephropathy

Abstract BACKGROUND AND AIMS In recent years, the dysregulated expression of microRNAs (miRs)—small molecules of noncoding RNA that epigenetically fine-tune post-transcriptional gene expression—has been increasingly implicated in the pathogenesis of IgA nephropathy (IgAN). Extracellular miRs, contained within extracellular vesicles such as exosomes and microvesicles, are thought to function as important intercellular and interorgan modes of communication in health and disease. In the current study, next-generation sequencing (NGS) and subsequent real-time quantitative polymerase chain reaction (RT-qPCR) validation were performed to identify serum miRs associated with a high risk of future kidney function decline in IgAN. We then went on to determine whether treatment with Nefecon® 16 mg/day for 9 months was capable of modifying the serum levels of miRs associated with high-risk IgAN. This study was supported by a grant from Calliditas Therapeutics AB. METHOD NGS was performed by Qiagen (Germany) on serum from patients with IgAN (10 at high risk and 10 at low risk of progression) or membranous nephropathy (MN, n=10), as well as healthy individuals (HS, n=10). Sequencing data were validated by RT-qPCR using TaqMan miR PCR assays in independent sets of serum samples (20 per cohort). Using the Total Exosome Isolation (from serum) reagent (Thermo Fisher Scientific, UK), extracellular exosomes were isolated from the serum of participants of the NEFIGAN trial from the placebo group (n=40) and Nefecon® 16 mg/day group (n=40) at the start of treatment (SOT) and end of treatment (EOT). RNA was isolated and levels of miRs-483-5p and -122-5p were measured by RT-qPCR. The NEFIGAN trial (NCT01738035) was a randomized, double-blind, placebo-controlled Phase 2b trial designed to assess the safety and efficacy of Nefecon® a novel targeted-release formulation of budesonide, designed to deliver the drug to the distal ileum in patients with IgAN. The trial comprised a 6-month run-in, a 9-month treatment and a 3-month follow-up phase. A total of 48 patients received Nefecon® 16 mg/day, 51 patients received Nefecon® 8 mg/day and 50 patients received placebo. The key result of the study was that Nefecon® 16 mg/day, added to optimized renin–angiotensin system blockade, reduced proteinuria and stabilized estimated glomerular filtration rate in patients with IgAN. These findings have now been replicated in the NefIgArd study, which released data in 2021. RESULTS miRs-483-5p and -122-5p were significantly overexpressed in the serum of patients with IgAN at high risk of progression compared with those who had stable IgAN or HS, but not compared with patients with MN. Both miRs were also found to be significantly increased in extracellular exosomes in high-risk IgAN compared with low-risk IgAN, HS and MN. Interestingly, levels of exosomal miRs-483-5p and -122-5p did not correlate with total serum IgA, IgA1, galactose-deficient IgA1 or IgA–IgG immune complex levels, suggesting a novel mechanism of action. Treatment with 16 mg/day of Nefecon® led to a significant reduction in the exosomal levels of miR-122-5p, while no change in miR-483-5p levels was observed in the treated group. CONCLUSION These data reveal a dysregulation of systemic exosomal miR expression in IgAN, and demonstrate for the first time that it is possible to pharmacologically modify the miR content of circulating exosomes in IgAN. Treatment with Nefecon® 16 mg/day for 9 months selectively downregulated exosomal miR-122-5p, while having no effect on exosomal miR-483-5p levels, arguing against a generalized ‘anti-miR’ effect of Nefecon®. Studies are ongoing to both precisely delineate the cellular source(s) of these exosomes and determine the downstream impact of these changes on glomerular and tubulointerstitial biology.

The Role of Tamm‐Horsfall Protein in the Pathogenesis of Crystalline Nephropathy

Acute crystalline nephropathy is closely related to glomerular and tubulointerstitial injury, but few studies have investigated the role of Tamm Horsfall protein (THP) in this condition. Thus, we hypothesize that THP can modulate the innate immune system and play a renoprotective role in physiological conditions. However, in crystalline‐induced AKI, reduced THP synthesis may induces inflammatory response. The aim of the current study is to understand the role of exogenous THP administration in an experimental model of crystalline‐induced AKI. Eight weeks old C57BL/6J mice were randomly allocated into four groups (n=5/group): 1. Control (received saline 0.9%); 2. THP (treated with exogenous THP – 5μg per animal, single injection i.p); 3. NaOx (treated with sodium oxalate – 9mg/100g of body weight, single injection i.p); 4. NaOx + THP. After the treatments, the animals were placed in metabolic cages for 24 hours for analysis of metabolic parameters and urinary protein expression. At the end of the period, blood and kidney samples were collected under the effect of anesthetics for further analysis. The experimental protocols, including euthanasia were conducted in accordance with CEUA (3894050221). The results presented as the mean ± S.D. were analyzed by two‐way ANOVA and a Bonferroni post hoc test using GraphPad Prism software. p &lt; 0.05 was considered statistically significant. Our results revealed that the treatment with exogenous THP alone did not change any parameter analyzed in comparison to the control group. The treatment with NaOx did not change the body weight and urinary flow. However, multiple comparisons tests revealed that NaOx treated group exhibited significant decrease in food intake when compared to the control animals and this effect was attenuated in the cotreated group [(g) NaOx: 1.5±0.5 vs. Control: 7.0±0.8, p = 0.0081 and NaOx + THP: 4.0±1.5 vs. NaOx: 1.5±0.5, p = 0.0292]. Furthermore, the interaction between NaOx/THP was confirmed by two‐way ANOVA (p = 0.0236). The NaOx treatment resulted in increase of water intake [(mL/24h) NaOx: 4.4±0.5 vs. Control: 1.7±0.9, p= 0.0165], without interference of the THP in the cotreated group. The NaOx treatment resulted in albuminuria compared to the control group [(arbitrary units) NaOx: 101.613±35.415 vs. Control: 35.965±8,351, p = 0.0361], without significant interference of the THP in the cotreated group, while endogenous THP content in urine decreased in comparison to the control group [(arbitrary units) NaOx: 1.347±0.226 vs. Control: 1.924±0.162, p = 0.0065]. However, the cotreatment with exogenous THP recovered this parameter [(arbitrary units) NaOx + THP: 1.861±0.176 vs. NaOx: 1.347±0.226, p = 0.0216] and the interaction between NaOx/THP was confirmed by two‐way ANOVA (p = 0.0302). NaOx treatment resulted in increased kidney weight in comparison to the control group [(mg/g) NaOx: 8.8±0.3 vs. Control: 6.2±0.6, p = 0.0002] and this effect was attenuated in the cotreated group [(mg/g) NaOx + THP group: 7.1±1.0 vs. NaOx group: 8.8±0.3, p = 0.0150]. The interaction between NaOx/THP was confirmed by two‐way ANOVA (p = 0.0063). Thus, our preliminary results indicate that exogenous THP may have a renoprotective effect on crystalline‐induced AKI.

A Novel Study of Protein Kinase C Beta Gene Polymorphism (rs3760106) and Protein Kinase C Activity Levels as a Predictor of Nephropathy Complications in Iraqi Diabetic Patients

Objective: This study aimed to investigate the relation between the risk of (PRKCB-1504 C/T) gene polymorphisms and diabetic nephropathy pathogenesis and its association with its levels and some other biomarkers in serum of Iraqi diabetic nephropathy patients.&#x0D; Methods: A cross-sectional study was performed on 130 samples obtained from Al-Hussein Teaching Hospital / Kerbala – Iraq during Feb., 2020 to March. 2021. Seventy three patients of them with type 2 diabetes mellitus (T2D) and the remaining patients with type 2 diabetes mellitus with nephropathy complications (DN). Phenotypic analysis included determination of protein kinase C (PKC) activity levels, HbA1c%, serum insulin levels and renal function tests. Five ml of whole blood was obtained from each patients, 4.0 ml was centrifuged for serum separation used for biomarkers determinations and the remaining 1.0 ml was used for genomic DNA extraction for molecular analysis and polymorphism of PRKCB (rs3760106) by allele specific-amplification refractory mutational system-polymerase chain reaction (allele specific ARMS-PCR), followed by electrophoresis on 1% agarose gel. Various statistical analyses were applied to analyze the obtained data.&#x0D; Results: The amplification of the PRKCB gene gives one genotypes as indicated by (200 bp) bands for those with homozygous wild type (CC), homozygous mutant (TT) genotypes and two genotypes bands (200 bp) for those with heterozygous (CT). Genotype frequencies of rs3760106 polymorphism were found to be consistent with Hardy–Weinberg equilibrium. Allele frequencies (23.3 %, 26.7 %, 50 %) of CC, CT, TT in cases of DN group. While the frequencies in the non-DN group were (30 %, 45%, 25%) and for healthy control group were (50%, 33.4%, 16.6%) for wild, heterozygous, and homozygous in an order. In healthy control group, the risk of diabetic nephropathy was significantly higher among carriers of T allele under codominant TT (OR=6.42, 95%CI=(1.66-24.85), P=0.007), dominant CT+TT (OR=3.2, 95%CI = (1.08-9.95),P=0.03) and recessive model (OR=5, 95%CI = (1.51-16.56), P=0.008) while in T2DM without nephropathy the risk of diabetic nephropathy was significantly higher among carrier of T allele under recessive model (0R=3, 95%CI = (1.09-28.25), P= 0.003). Serum level of PKC-B1 activity was significantly higher among DN group than T2DM and control groups (43.35 ± 18.69, 30.35 ± 11.96, 27.42 ± 10.31, P=0.001), also PKC-B1 activity in DN group was significantly correlated with fasting blood glucose, HOMA-IR and renal function tests such as GFR, urea and creatinine.&#x0D; Conclusion: This study indicates that the PRKCB (C/T-1504) rs3760106 single nucleotide polymorphism was significantly associated with increased diabetic nephropathy susceptibility of Iraqi patients with T2DM and serum level of PKCB activity was associated with increase the risk of diabetic nephropathy complications.

Streptococcus pyogenes: phenomenon of nonimmune binding of human immunoglobulins and its role in pathology

M and M-like proteins represent the main pathogenicity factors of Streptococcus pyogenes, a widely spread and potentially lethal bacterial pathogen. These proteins provide resistance of the microbe to innate and adaptive immune response, due to attraction of specific human proteins to the streptococcal surface. Nonimmune binding of immunoglobulins G (IgG) and A (IgA) via their Fc domains to M and M-like proteins was described over 40 years ago, but its role for the pathogenicity of Streptococcus pyogenes is far from definite resolution. The discovery of this phenomenon should be considered among quite significant achievements of modern microbiology, since it had a huge impact upon development of innovative approaches, technologies and tools for microbiological, immunological and molecular diagnostics. It also promoted fundamental studies in pathogenesis of distinct infectious states and their complications caused by S. pyogenes. The non-immune binding of host immunoglobulins was previously suggested to be important mainly in immune conditions on the surface of mucous membranes and their secretions, but not in blood plasma, whereas other studies have pointed to significance of this phenomenon in protecting microbes from phagocytosis in non-immune blood of the host. It was also shown that the effect of Fc-binding causes increased pathogenicity of streptococci both in primary focus of infection, and during chronical course of the process, thus contributing to development of autoimmune diseases caused by S. pyogenes infection and leading to tissue damage in experimental animals. The experimental autoimmune process can be prevented by administering purified Fc fragments of immunoglobulins to the animals, blocking this process at the early stages of its development. A significant place in pathogenesis of IgA nephropathy (IgAN) belongs to streptococcal diseases. IgAN has been described as a mesangial proliferative process, due to initial IgA-Fcα deposition in renal mesangium cells. The data from literature describe successful modeling of individual IgAN traits, and expand our understanding of pathogenic properties and functions of Fcα binding receptor M proteins of S. pyogenes. The data reviewed in the article also presume the relevance of recently proposed ideas about an important role of non-immune Ig binding in streptococcal diseases, even in cases that differ in their development mechanism. These studies, including possible search for tools and techniques of preventive and potentially therapeutic applications, require additional efforts to study the binding of Fc fragments of IgG and IgA to M and M-like proteins of Streptococcus pyogenes.

Diagnostic Potential of Plasma IgA1 O-Glycans in Discriminating IgA Nephropathy From Other Glomerular Diseases and Healthy Participants.

Background: Aberrant O-glycosylation of IgA1 plays an important role in IgA nephropathy pathogenesis. Previous proteomic studies analyzed O-glycans of the circulating IgA1 hinge region and found that the N-acetylgalactosamine (GalNAc) and galactose numbers in the hinge region of IgA1 of patients with IgA nephropathy were lower than those in healthy participants. However, the diagnostic performance of the O-glycosylation traits in the hinge region of plasma IgA1 for IgA nephropathy remains unelucidated. The present study aimed to determine the difference in plasma IgA1 hinge region O-glycoforms among IgA nephropathy, non-IgA nephropathy disease controls, and healthy participants, and to further evaluate the diagnostic performance of plasma IgA1 glycosylation traits. Methods: Sixty-two patients with biopsy-proven primary IgA nephropathy, 30 age- and sex-matched non-IgA nephropathy disease controls (10 patients with membranous nephropathy, 10 with focal segmental glomerulosclerosis, and 10 with minimal change disease), and 30 healthy participants were prospectively recruited. Plasma galactose deficient-IgA1 levels were measured using a KM55 kit. Plasma IgA was extracted using IgA immunoaffinity beads. After de-N-glycosylation, reduction, alkylation, trypsin digestion, and O-glycopeptide enrichment via hydrophilic interaction liquid chromatography, liquid chromatography tandem mass spectrometry (LC-MS/MS) was applied to analyze the IgA1 O-glycosylation patterns and we derived the plasma IgA1 O-glycosylation traits. Results: Plasma IgA1 O-glycosylation patterns were significantly changed in IgA nephropathy patients compared to those with non-IgA nephropathy disease controls and healthy participants. The GalNAc number was lowest in IgA nephropathy patients. In addition, a similar result was observed for the galactose number in the IgA1 hinge region. These values showed moderate potential for discriminating between IgA nephropathy and the controls. When these values were combined, the area under the curve increased compared to when they were considered individually. When further adding a clinical indicator, the area under the curve of the GalNAc-galactose-IgA panel exceed 0.9 in discriminating IgA nephropathy from the controls. Conclusion: The amount of GalNAc and galactose in plasma IgA1 hinge region identified by glycoproteomics could be used as a diagnostic biomarker for IgA nephropathy. The panel containing GalNAc, galactose, and circulating IgA displayed excellent diagnostic performance and is promising for practical clinical applications.

New Insights into the Treatment of Glomerular Diseases: When Mechanisms Become Vivid.

Treatment for glomerular diseases has been extrapolated from the experience of other autoimmune disorders while the underlying pathogenic mechanisms were still not well understood. As the classification of glomerular diseases was based on patterns of juries instead of mechanisms, treatments were typically the art of try and error. With the advancement of molecular biology, the role of the immune agent in glomerular diseases is becoming more evident. The four-hit theory based on the discovery of gd-IgA1 gives a more transparent outline of the pathogenesis of IgA nephropathy (IgAN), and dysregulation of Treg plays a crucial role in the pathogenesis of minimal change disease (MCD). An epoch-making breakthrough is the discovery of PLA2R antibodies in the primary membranous nephropathy (pMN). This is the first biomarker applied for precision medicine in kidney disease. Understanding the immune system’s role in glomerular diseases allows the use of various immunosuppressants or other novel treatments, such as complement inhibitors, to treat glomerular diseases more reasonable. In this era of advocating personalized medicine, it is inevitable to develop precision medicine with mechanism-based novel biomarkers and novel therapies in kidney disease.

Mesangial cell-derived tenascin-C contributes to mesangial cell proliferation and matrix protein production in IgA nephropathy.

Tenascin-C (TNC), a non-structural extracellular matrix glycoprotein, is transiently expressed during development or after injury, playing an important role in injury and repair process. The potential role of TNC in the pathogenesis of IgA nephropathy (IgAN) remains to be clarified. Immunohistochemistry staining for TNC was conducted on paraffin-embedded slices from renal biopsies of 107 IgAN patients, and correlation analysis was made between mesangial TNC expression and clinic-pathological parameters. In situ hybridization for TNC mRNA was further performed to figure out the cells that express TNC within glomeruli. In vitro experiments were also carried out on mouse mesangial cells (SV40 MES13) to elucidate the effect of TNC on mesangial cells. TNC was expressed in the mesangial area of IgAN, as well as in fibrotic regions. Correlation analysis showed that higher mesangial TNC was associated with higher level of proteinuria, lower estimated glomerular filtration rate and more serious pathological lesions (MEST score). In situ hybridization revealed that abundant TNC mRNA expression was observed in the affected glomeruli of IgAN, but not in minimal change disease. Moreover, TNC mRNA co-localized with PDGFRβ mRNA, but not with PODXL mRNA, suggesting that TNC mRNA was expressed in the mesangial cells within glomeruli in IgAN. In vitro experiments showed that exogenous TNC promoted matrix protein production and mesangial cell proliferation, which was attenuated by an epidermal growth factor receptor inhibitor. Taken together, these results suggest that mesangial cell-derived TNC contributes to mesangial matrix expansion and mesangial cell proliferation, which is a potential therapeutic target in IgAN.

Complement induces podocyte pyroptosis in membranous nephropathy by mediating mitochondrial dysfunction

Podocyte damage mediated by in situ complement activation in the glomeruli is a key factor in the pathogenesis of membranous nephropathy (MN), but the molecular mechanism has not been fully elucidated. Pyroptosis is a special type of programmed cell death, mediate inflammatory response and induce tissue injury. However, it is not clear whether pyroptosis is involved in the development and progression of MN. Here, we report that pyroptosis plays an important role in promoting podocyte injury in MN. We first observed the occurrence of pyroptosis in the kidneys of MN patients and validated that complement stimulation triggered pyroptosis in podocytes and that inhibiting pyroptosis reversed complement-induced podocyte damage in vitro. In addition, stimulation of complement caused mitochondrial depolarization and reactive oxygen species (ROS) production in podocytes, and inhibition of ROS reversed complement-induced pyroptosis in podocytes. Interestingly, inhibition of pyroptosis in turn partially alleviated these effects. Furthermore, we also found the involvement of pyroptosis in the kidneys of passive Heymann nephritis (PHN) rats, and inhibitors of pyroptosis-related molecules relieved PHN-induced kidney damage in vivo. Our findings demonstrate that pyroptosis plays a critical role in complement-induced podocyte damage in MN and mitochondrial dysfunction is an important mechanism underlying this process. It provides new insight that pyroptosis may serve as a novel therapeutic target for MN treatment in future studies.

Protective effect of morin by targeting mitochondrial reactive oxygen species induced by hydrogen peroxide demonstrated at a molecular level in MDCK epithelial cells.

The development of diabetic nephropathy is aided by the presence of oxidative stress. Morin, a natural flavonoid molecule, has been shown to have antioxidant and anti-diabetic properties. However, little is known about the mechanism of its protective effect in diabetic nephropathy pathogenesis caused by oxidative stress. Using Madin-Darby canine kidney (MDCK) cells as a working model, the current study investigates the detailed mechanism of morin's beneficial action. In hydrogen peroxide-induced oxidative stressed MDCK cells, there was a considerable rise in intracellular ROS and decreased antioxidant enzyme levels. Morin has a higher binding affinity for the antioxidant receptor; according to in silico study using molecular docking and ADMET, it is predicted to be an orally active molecule. While morin administration increased SOD and CAT activity in oxidative stress-induced MDCK cells, it also reduced mitochondrial oxidative stress and apoptosis. Furthermore, the present study discovered the molecular mechanism through which morin reduced oxidative stress in MDCK cells by upregulating antioxidant enzyme molecules including GST, GPx, and GCS. These findings suggest that morin reduces H2O2-induced oxidative stress, reduces DNA oxidative damage, and prevents the depletion of antioxidant genes in MDCK cells.

Adenine overload induces ferroptosis in human primary proximal tubular epithelial cells

The pathogenesis of crystal nephropathy involves deposition of intratubular crystals, tubular obstruction and cell death. The deposition of 8-dihydroxyadenine (DHA) crystals within kidney tubules, for instance, is caused by a hereditary deficiency of adenine phosphoribosyl transferase in humans or adenine overload in preclinical models. However, the downstream pathobiological patterns of tubular cell attrition in adenine/DHA-induced nephropathy remain poorly understood. In this study, we investigated: (i) the modes of adenine-induced tubular cell death in an experimental rat model and in human primary proximal tubular epithelial cells (PTEC); and (ii) the therapeutic effect of the flavonoid baicalein as a novel cell death inhibitor. In a rat model of adenine diet-induced crystal nephropathy, significantly elevated levels of tubular iron deposition and lipid peroxidation (4-hydroxynonenal; 4-HNE) were detected. This phenotype is indicative of ferroptosis, a novel form of regulated necrosis. In cultures of human primary PTEC, adenine overload-induced significantly increased mitochondrial superoxide levels, mitochondrial depolarisation, DNA damage and necrotic cell death compared with untreated PTEC. Molecular interrogation of adenine-stimulated PTEC revealed a significant reduction in the lipid repair enzyme glutathione peroxidase 4 (GPX4) and the significant increase in 4-HNE compared with untreated PTEC, supporting the concept of ferroptotic cell death. Moreover, baicalein treatment inhibited ferroptosis in adenine-stimulated PTEC by selectively modulating the mitochondrial antioxidant enzyme superoxide dismutase 2 (SOD2) and thus, suppressing mitochondrial superoxide production and DNA damage. These data identify ferroptosis as the primary pattern of PTEC necrosis in adenine-induced nephropathy and establish baicalein as a potential therapeutic tool for the clinical management of ferroptosis-associated crystal nephropathies (e.g., DHA nephropathy, oxalate nephropathy).

Inhibition of endoplasmic reticulum stress signaling rescues cytotoxicity of human apolipoprotein-L1 risk variants in Drosophila

Risk variants of the apolipoprotein-L1 (APOL1) gene are associated with severe kidney disease, putting homozygous carriers at risk. Since APOL1 lacks orthologs in all major model organisms, a wide range of mechanisms frequently in conflict have been described for APOL1-associated nephropathies. The genetic toolkit in Drosophila allows unique invivo insights into disrupted cellular homeostasis. To perform a mechanistic analysis, we expressed human APOL1 control and gain-of-function kidney risk variants in the podocyte-like garland cells of Drosophila nephrocytes and a wing precursor tissue. Expression of APOL1 risk variants was found to elevate endocytic function of garland cell nephrocytes that simultaneously showed early signs of cell death. Wild-type APOL1 had a significantly milder effect, while a control transgene with deletion of the short BH3 domain showed no overt phenotype. Nephrocyte endo-lysosomal function and slit diaphragm architecture remained unaffected by APOL1 risk variants, but endoplasmic reticulum (ER) swelling, chaperone induction, and expression of the reporter Xbp1-EGFP suggested an ER stress response. Pharmacological inhibition of ER stress diminished APOL1-mediated cell death and direct ER stress induction enhanced nephrocyte endocytic function similar to expression of APOL1 risk variants. We confirmed APOL1-dependent ER stress in the Drosophila wing precursor where silencing the IRE1-dependent branch of ER stress signaling by inhibition with Xbp1-RNAi abrogated cell death, representing the first rescue of APOL1-associated cytotoxicity invivo. Thus, we uncovered ER stress as an essential consequence of APOL1 risk variant expression invivo in Drosophila, suggesting a central role of this pathway in the pathogenesis of APOL1-associated nephropathies.

POS-311 Long-term effects of contrast-enhanced intervention on progression of chronic kidney disease: A retrospective cohort study

In recent years, with increasing importance of accurate diagnosis and treatment, imaging interventions using a contrast medium have become inevitable. However, iodinated contrast media often cause hypersensitivity, and at times even to severe shock. Despite years of research, the pathogenesis of contrast-induced nephropathy (CIN) is not fully elucidated. Elderly people and those with chronic kidney disease (CKD) are especially at risk. CIN develops in 4–11% of patients with moderate renal dysfunction.

POS-098 HYDROXYCHLOROQUINE PREVENTS THE DISEASE PROGRESSION IN THE MURINE IGA NEPHROPATHY MODEL VIA INHIBITING TLR9/TLR7 SIGNALS AND RELATED CYTOKINES

Galactose-deficient IgA1 (Gd-IgA1) plays a crucial role in the pathogenesis of IgA nephropathy (IgAN). There has been increasing evidence suggested overactivation of Toll-like receptor (TLR) signals, especially TLR9 and TLR7, is involved in the production of Gd-IgA1 and affects disease progression of IgAN. Recently, several clinical trials suggested hydroxychloroquine (HCQ) which is known to suppress TLR9 and TLR7 signals might be effective to reduce proteinuria in patients with IgAN. However, because of the complicated pharmacological effects of HCQ, the exact mechanism in treating IgAN has not been fully elucidated.