A region-level contrastive learning-based deep model for glomerular ultrastructure segmentation on electron microscope images / 南方医科大学学报

OBJECTIVE@#We propose a novel region- level self-supervised contrastive learning method USRegCon (ultrastructural region contrast) based on the semantic similarity of ultrastructures to improve the performance of the model for glomerular ultrastructure segmentation on electron microscope images.@*METHODS@#USRegCon used a large amount of unlabeled data for pre- training of the model in 3 steps: (1) The model encoded and decoded the ultrastructural information in the image and adaptively divided the image into multiple regions based on the semantic similarity of the ultrastructures; (2) Based on the divided regions, the first-order grayscale region representations and deep semantic region representations of each region were extracted by region pooling operation; (3) For the first-order grayscale region representations, a grayscale loss function was proposed to minimize the grayscale difference within regions and maximize the difference between regions. For deep semantic region representations, a semantic loss function was introduced to maximize the similarity of positive region pairs and the difference of negative region pairs in the representation space. These two loss functions were jointly used for pre-training of the model.@*RESULTS@#In the segmentation task for 3 ultrastructures of the glomerular filtration barrier based on the private dataset GlomEM, USRegCon achieved promising segmentation results for basement membrane, endothelial cells, and podocytes, with Dice coefficients of (85.69 ± 0.13)%, (74.59 ± 0.13)%, and (78.57 ± 0.16)%, respectively, demonstrating a good performance of the model superior to many existing image-level, pixel-level, and region-level self-supervised contrastive learning methods and close to the fully- supervised pre-training method based on the large- scale labeled dataset ImageNet.@*CONCLUSION@#USRegCon facilitates the model to learn beneficial region representations from large amounts of unlabeled data to overcome the scarcity of labeled data and improves the deep model performance for glomerular ultrastructure recognition and boundary segmentation.

Effects and mechanisms of total flavones of Abelmoschus manihot in improving insulin resistance and podocyte epithelial-mesenchymal transition in diabetic kidney disease based on IRS1/PI3K/Akt pathway / 中国中药杂志

This study aimed to explore the effects and mechanisms of total flavones of Abelmoschus manihot(TFA), the extracts from traditional Chinese medicine indicated for kidney diseases, on insulin resistance(IR) and podocyte epithelial-mesenchymal transition(EMT) in diabetic kidney disease(DKD), and further to reveal the scientific connotation. Thirty-two rats were randomly divided into a normal group, a model group, a TFA group, and a rosiglitazone(ROS) group. The modified DKD model was induced in rats by methods including high-fat diet feeding, unilateral nephrectomy, and streptozotocin(STZ) intraperitoneal injection. After modeling, the rats in the four groups were given double-distilled water, TFA suspension, and ROS suspension correspondingly by gavage every day. At the end of the 8th week of drug administration, all rats were sacrificed, and the samples of urine, blood, and kidney tissues were collected. The parameters and indicators related to IR and podocyte EMT in the DKD model rats were examined and observed, including the general condition, body weight(BW) and kidney weight(KW), the biochemical parameters and IR indicators, the protein expression levels of the key signaling molecules and structural molecules of slit diaphragm in the renal insulin receptor substrate(IRS) 1/phosphatidylinositol 3-kinase(PI3K)/serine-threonine kinase(Akt) pathway, foot process form and glomerular basement membrane(GBM) thickness, the expression of the marked molecules and structural molecules of slit diaphragm in podocyte EMT, and glomerular histomorphological characteristics. The results showed that for the DKD model rats, both TFA and ROS could improve the general condition, some biochemical parameters, renal appearance, and KW. The ameliorative effects of TFA and ROS were equivalent on BW, urinary albumin(UAlb)/urinary creatinine(UCr), serum creatinine(Scr), triglyceride(TG), and KW. Secondly, they could both improve IR indicators, and ROS was superior to TFA in improving fast insulin(FIN) and homeostasis model assessment of insulin resistance(HOMA-IR). Thirdly, they could both improve the protein expression levels of the key signaling molecules in the IRS1/PI3K/Akt pathway and glomerulosclerosis in varying degrees, and their ameliorative effects were similar. Finally, both could improve podocyte injury and EMT, and TFA was superior to ROS. In conclusion, this study suggested that podocyte EMT and glomerulosclerosis could be induced by IR and the decreased activation of the IRS1/PI3K/Akt pathway in the kidney in DKD. Similar to ROS, the effects of TFA in inhibiting podocyte EMT in DKD were related to inducing the activation of the IRS1/PI3K/Akt pathway and improving IR, which could be one of the scientific connotations of TFA against DKD. This study provides preliminary pharmacological evidence for the development and application of TFA in the field of diabetic complications.

Role of podocyte injury signaling pathway in steroid-resistant nephrotic syndrome and research progress in traditional Chinese medicine intervention / 中国中药杂志

As one of the main diseases leading to end-stage renal disease, steroid-resistant nephrotic syndrome(SRNS) can cause serious complications such as infection. Without effective control, this disease can further lead to the malignant development of the renal function, bringing serious social and economic burdens. As previously reported, the formation of SRNS is mostly related to the podocyte injury in the body, i.e., the injury of glomerular visceral epithelial cells. Phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt) signaling pathway, nuclear transcription factor-κB(NF-κB) signaling pathway, mammalian target of rapamycin(mTOR)/adenosine monophosphate(AMP)-activated protein kinase(AMPK), transforming growth factor(TGF)-β1/Smads, and other signaling pathways are classical signaling pathways related to podocyte injury. By regulating the expression of signaling pathways, podocyte injury can be intervened to improve the adhesion between podocyte foot processes and glomerular basement membrane and promote the function of podocytes, thereby alleviating the clinical symptoms of SRNS. Through the literature review, traditional Chinese medicine(TCM) has unique advantages and an important role in intervening in podocyte injury. In the intervention in podocyte injury, TCM, by virtue of multi-target and multi-pathway role, can regulate and intervene in podocyte injury in many ways, alleviate the clinical symptoms of SRNS, and interfere with the progress of SRNS, reflecting the unique advantages of TCM. On the other hand, TCM can directly or indirectly inhibit podocyte injury by regulating the above signaling pathways, which can not only promote the effect of hormones and immunosuppressants and shorten the course of treatment, but also reduce the toxic and side effects caused by various hormones and immunosuppressants to exert the advantages of small side effects and low price of TCM. This article reviewed TCM in the treatment of SRNS by interfering with podocyte injury-related signaling pathways and is expected to provide a reference for the in-depth study of TCM in the treatment of SRNS, as well as a theoretical basis and a new direction for the clinical application of TCM to shorten the course of treatment of SRNS and delay the progression to end-stage renal disease.

Hepatitis B virus X protein promotes podocyte pyroptosis in hepatitis B virus-associated glomerulonephritis by down-regulating microRNA -223 targeting NLRP3 inflammasome / 中华肝脏病杂志

Objective: To investigate the potential function and related mechanism of microRNA-223 (miRNA-223) in the podocyte pyroptosis of hepatitis B virus (HBV)-associated glomerulonephritis induced by HBV X protein (HBx). Methods: HBx-overexpressing lentivirus was transfected into human renal podocytes to mimic the pathogenesis of HBV-GN. Real-time fluorescence quantitative PCR and Western blotting experiments were used to detect the mRNA and protein expression of pyroptosis-related proteins [nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC) and caspase-1], and inflammatory factors (interleukin-1β and interleukin-18), respectively.TUNEL staining and flow cytometry were used to detect the number of pyroptosis cells. Immunofluorescence staining was used to detect the expression of podocytes biomarkers desmin and nephrin; Hoechst 33342 staining was used to observe the morphological and quantitative changes of podocyte nuclei. Enzyme-linked immunosorbent assay was used to measure caspase-1 activity. The dual luciferase reporter gene assay was used to verify the downstream target of miRNA-223. Podocytes were divided into the following nine groups: control group (no special treatment), empty plasmid group (transfected with empty plasmid), HBx overexpression group (transfected with HBx overexpression lentivirus), HBx overexpression+miRNA-223 mimic group (transfected with HBx overexpression lentivirus and miRNA-223 mimic), HBx overexpression+miRNA-223 inhibitor group (transfected with HBx overexpression lentivirus and miRNA-223 inhibitor), HBx overexpression+miRNA-223 mimic+NLRP3 group (transfected with HBx overexpression lentivirus, miRNA-223 mimic and NLRP3 overexpression plasmid), HBx overexpression+miRNA-223 mimic+ NLRP3 siRNA group (transfected with HBx overexpression lentivirus, miRNA-223 mimic and NLRP3 siRNA), HBx overexpression+miRNA-223 inhibitor+NLRP3 group (transfected with HBx overexpression lentivirus, miRNA-223 inhibitor and NLRP3 overexpression plasmid), HBx overexpression+miRNA-223 inhibitor+NLRP3 siRNA group (transfected with HBx overexpression lentivirus, miRNA-223 inhibitor and NLRP3 siRNA). Results: miRNA-223 was down-regulated in HBx overexpression group compared with the control group (P < 0.05). TUNEL and immunofluorescence staining showed that NLRP3 knockdown attenuated podocyte injury and pyroptosis induced by HBx overexpression (P < 0.05). Dual luciferase reporter gene assay demonstrated that NLRP3 was one of the downstream targets of miRNA-223. Rescue experiments revealed that NLRP3 overexpression weakened the protective effect of miRNA-223 in podocyte injury (P < 0.05). The addition of miRNA-223 mimic and NLRP3 siRNA decreased the expression of NLRP3 inflammasome and cytokines, and reduced the number of pyroptosis cells induced by HBx overexpression (all P < 0.05); The addition of miRNA-223 inhibitor and NLRP3 overexpression plasmid significantly increased the expression of NLRP3 inflammasome and cytokines, caspase-1 activity, and the number of pyroptosis cells (all P < 0.05). Conclusion: HBx may promote podocyte pyroptosis of HBV-GN via downregulating miRNA-223 targeting NLRP3 inflammasome, suggesting that miRNA-223 is expected to be a potential target for the treatment of HBV-GN.

Expression and role of the TRPC family in TGF-β1-induced calcium influx in podocytes / 生理学报

The TRPC family consists of multiple important cationic channels in mammals that participate in a variety of physiological and pathological processes. Our previous studies have shown that transforming growth factor-β1 (TGF-β1) increases the expression of TRPC6 in podocytes, but the roles of other members of the TRPC family in podocytes require further investigation. In this study, we investigated the effect of TGF-β1 on the expression of the TRPC family and the role of the TRPC family in the changes of the intracellular Ca2+ concentration ([Ca2+]i) in podocytes induced by TGF-β1. The model of podocyte injury was established by treatment with TGF-β1 in immortalized glomerular podocytes (MPC5) in vitro. qRT-PCR and Western blot were used to detect the effect of TGF-β1 on the mRNA and protein expression of each TRPC family member. After the expression of each TRPC family member was knocked down by a siRNA-based approach and blocked by SKF96365, respectively, free cytosolic Ca2+ was measured using the fluorescent Ca2+ indicator Fluo-3/AM, and the dynamic change of [Ca2+]i in podocytes was detected by a dynamic high-speed calcium imaging system. The results showed that TGF-β1 increased the protein expression of TRPC1/3/6 in podocytes, but had no effects on the protein expression of TRPC4. The protein expression levels of TRPC5/7 were only affected by 4 ng/mL and 8 ng/mL TGF-β1, respectively. TGF-β1 increased TRPC1/3/6 mRNA levels in podocytes, however had no effects on TRPC4/5/7 mRNA. TGF-β1 significantly increased [Ca2+]i in podocytes. Knockdown of TRPC1/4/5/7 in podocytes had no significant effect on the [Ca2+]i induced by TGF-β1, but TRPC3/6 knockdown significantly decreased the [Ca2+]i. There was no significant difference in the [Ca2+]i between the TRPC6 siRNA-treated group and SKF96365-treated group, but the [Ca2+]i of the TRPC3 siRNA-treated group was significantly higher than that of SKF96365-treated group. These results demonstrate that TGF-β1 increases the expression of the TRPC1/3/6 in podocytes. TGF-β1 increases [Ca2+]i in podocytes, which is dependent on the TRPC3/6 expression. Our results also suggest that the effect of TRPC6 on [Ca2+]i in podocytes may be greater than that of TRPC3.

Effect of Huangkui on mouse podocytes under high glucose environment / Efecto de Huangkui en podocitos de ratón en un entorno de glucosa alta

To explore a new underlying molecular mechanism of Huangkui Extract Powder (HKEP) in the alleviation of diabetic nephropathy (DN). Murine immortalized podocytes were divided into (i) normal glucose (NG, 5.6 mM), (ii) NG + HKEP (0.45 g/L), (iii) HG, and (iv) HG + HKEP (0.45 g/L) groups. MTT assay and flow cytometry were used to detect the podocyte proliferation, apoptosis and cell cycle. Cell viability was inhibited, and apoptosis increased in(iii) HG group compared with (i) NG group (p<0.05). mRNA and protein expression of nephrin and podocin significantly decreased in (iii) HG group compared with (i) NG group (p<0.05). When compared with (iii) HG group, (iv) HG + HKEP group had higher cell viability, lower apoptotic rate and higher mRNA and protein expression of nephrin and podocin (p<0.05). HKEP can attenuate HG-induced podocyte damage, which may be one of the mechanisms of HKEP for attenuating DN.

Explorar un nuevo mecanismo molecular subyacente del extracto del polvo de Huangkui (HKEP) en el alivio de la nefropatía diabética (ND). Los podocitos murinos inmortalizados se dividieron en (i) grupos de glucosa normal (NG, 5,6 mM), (ii) NG + HKEP (0,45 g/L), (iii) HG y (iv) HG + HKEP (0,45 g/L). Se utilizaron el ensayo MTT y la citometría de flujo para detectar la proliferación de podocitos, la apoptosis y el ciclo celular. La viabilidad celular se inhibió y la apoptosis aumentó en el grupo (iii) HG en comparación con el grupo (i) NG (p<0,05). La expresión de ARNm y proteínas de nefrina y podocina disminuyó significativamente en el grupo (iii) HG en comparación con el grupo (i) NG (p<0,05). En comparación con el grupo (iii) HG, el grupo (iv) HG + HKEP tuvo una mayor viabilidad celular, una tasa de apoptosis más baja y una expresión de ARNm y proteínas más altas de nefrina y podocina (p<0,05). HKEP puede atenuar el daño de los podocitos inducido por HG, que puede ser uno de los mecanismos de HKEP para atenuar la DN.

Effects and mechanisms of Supplemented Gegen Qinlian Decoction Formula against podocyte pyroptosis and insulin resistance in model rats with diabetic kidney disease / 中国中药杂志

This study explored the in vivo effects and mechanisms of the modern classical prescription Supplemented Gegen Qinlian Decoction Formula(SGDF) against diabetic kidney disease(DKD). Sixty rats were randomly divided into the normal group, model group, SGDF group, and rosiglitazone(ROS) group. The modified DKD rat model was established by employing the following three methods: exposure to high-fat diet, unilateral nephrectomy, and intraperitoneal injection of streptozotocin(STZ). After modeling, rats in the four groups were treated with double distilled water, SGDF suspension, and ROS suspension, respectively, by gavage every day. At the end of the 6 th week of drug administration, all the rats were sacrificed for collecting urine, blood, and kidney tissue, followed by the examination of rat general conditions, urine and blood biochemical indicators, glomerulosclerosis-related indicators, podocyte pyroptosis markers, insulin resistance(IR)-related indicators, and key molecules in the insulin receptor substrate(IRS) 1/phosphatidylinositol-3-kinase(PI3 K)/serine threonine kinase(Akt) signaling pathway. The results showed that SGDF and ROS improved the general conditions, some renal function indicators and glomerulosclerosis of DKD model rats without affecting the blood glucose(BG). Besides, they ameliorated the expression characteristics and levels of podocyte pyroptosis markers, alleviated IR, and up-regulated the protein expression levels of the key molecules in IRS1/PI3 K/Akt pathway to varying degrees. In conclusion, similar to ROS, SGDF relieves DKD by targeting multiple targets in vivo. Specifically, it exerts the therapeutic effects by alleviating podocyte pyroptosis and IR. This study has preliminarily provided the pharmacological evidence for the research and development of new drugs for the treatment of DKD based on SGDF.

Period circadian clock 3 inhibits palmitic acid-induced oxidative stress and inflammatory factor secretion in podocytes / 中南大学学报(医学版)

OBJECTIVES@#High fat-induced podocyte injury is one of the important factors leading to obesity related nephropathy (ORG), but the mechanism is not clear. This study aims to explore the mechanism of period circadian clock 3 (PER3) in the oxidative stress and inflammation induced by palmitic acid (PA) in podocytes.@*METHODS@#The C57BL/6J mice were fed with chow and high-fat diet for 16 weeks. The PER3 expression in kidney tissues were detected in the normal body weight group and the obesity group. The PER3 mRNA and protein expression were detected after the podocytes were induced with different concentrations (0, 50, 150 and 300 μmol/L) of PA for 48 h. The PER3 mRNA and protein expression were detected after the podocytes were induced with 150 μmol/L PA for 0, 24, 36, and 48 h. Triglyceride (TG) levels were examined in the PA group, the adenovirus (ad)-PER3+PA group, and the siRNA-PER+PA group after the podocytes were transfected by Ad-PER3 or small interfering RNA (siRNA)-PER3 for 48 h and subsequently were induced with 150 μmol/L PA for 48 h. The differential gene expression was detected using RNA sequencing (RNA-seq) after podocytes were transfected by siRNA-PER3 (siRNA-PER3 group) and siRNA-control (siRNA-control group), respectively. The mRNA levels of nephrin, podocin, podocalyxin, podoplanin, superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), catalase (CAT), and the levels of malondialdehyde (MDA), glutathione (GSH), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and interleukin-2 (IL-2) were detected after podocytes were transfected with Ad-PER3 or Ad-control for 48 h and then they were induced by 150 μmol/L PA for 48 h.@*RESULTS@#The PER3 was down-regulated in the obesity group compared with the normal body weight group (@*CONCLUSIONS@#PER3 can decrease the PA-induced oxidative stress and inflammatory factor secretion via inhibiting the lipogenesis in podocytes.

Influence of long non-coding RNA Gm15645 on the podocyte injury in diabetic nephropathy / 中华医学遗传学杂志

OBJECTIVE@#To explore the influence of long non-coding (lnc) RNA Gm15645 on the podocyte injury in mice with diabetic nephropathy.@*METHODS@#Male db/db mice (with Type 2 diabetes) with a genetic background of C57BLKs/J and db/m mice (healthy) born in littermates were randomly divided into three groups. db/db group was injected with lncRNAGm15645 shRNA lentivirus with a podocyte-specific marker NPHS2; db/db blank group was injected with saline, and db/db control group was injected withnon-sense lentivirus. The results of PAS staining, pathological changes of renal tissue, relative expression of GSK-3beta, and podocin expression were compared.@*RESULTS@#lncRNAGm15 645 was overexpressed and podocin was down-regulated in the lentivirus overexpressed group. Mesangial cell proliferation, mesangial matrix hyperplasia, thickened basement membrane, widely fused foot process, and podocyte injury were observed by PAS staining. The expression of Gm15645 in the db/db group was significantly lower than that of the db/db blank group and db/db control group (P< 0.05), while the expression of podocin was higher (P< 0.05). Gm15645 was co-stained with podocin in renal tissue, and the target gene was GSK-3beta.@*CONCLUSION@#lncRNAGm15645 may provide an early biomarker for the occurrence of podocyte injury in diabetic nephropathy. The mechanism may be related to the feedback regulation of GSK-3beta gene.

MicroRNA-770-5p contributes to podocyte injury via targeting E2F3 in diabetic nephropathy

Diabetic nephropathy (DN) has been identified as the major cause of end-stage renal disease (ESRD) in most developed countries. MicroRNA-770-5p depletion could repress high glucose (HG)-triggered apoptosis in podocytes, and downregulation of E2F transcription factor 3 (E2F3) could facilitate podocyte injury. Nevertheless, whether E2F3 is involved in miR-770-5p knockdown-mediated improvement of DN is still unclear. The expression levels of miR-770-5p and E2F3 were detected in HG-treated podocytes by RT-qPCR. The expression levels of E2F3, apoptosis-related proteins Bcl-2 related X protein (Bax), B-cell lymphoma-2 (Bcl-2), Bad, apoptotic peptidase activating factor 1 (APAF1), C-caspase3, C-caspase7, and C-caspase9 were detected by western blot assay. The effects of miR-770-5p and E2F3 on HG-treated podocytes proliferation and apoptosis were detected by CCK-8 and flow cytometry assays. The interaction between miR-770-5p and E2F3 was predicted by Targetscan, and then verified by the dual-luciferase reporter assay. MiR-770-5p was upregulated and E2F3 was downregulated in HG-treated podocytes. MiR-770-5p inhibited proliferation and promoted apoptosis and E2F3 promoted proliferation and suppressed apoptosis in HG-treated podocytes. E2F3 is a target gene of miR-770-5p and it partially abolished the effect of miR-770-5p in HG-triggered proliferation and apoptosis of podocytes. MiR-770-5p deficiency blocked HG-induced APAF1/caspase9 pathway via targeting E2F3 in podocytes. We firstly confirmed that E2F3 was a target of miR-770-5p in podocytes. These findings suggested that miR-770-5p expedited podocyte injury by targeting E2F3, and the miR-770-5p/E2F3 axis might represent a pathological mechanism of DN progression.

Role of microRNA-17-5p in the pathogenesis of pediatric nephrotic syndrome and related mechanisms / 中国当代儿科杂志

OBJECTIVE@#To study the role of microRNA-17-5p (miR-17-5p) in the pathogenesis of pediatric nephrotic syndrome (NS) and its effect on renal podocyte apoptosis via the activin A (ActA)/Smads pathway.@*METHODS@#An analysis was performed on 55 children with NS (NS group) who were admitted from March 2018 to March 2019. Fifty healthy children who underwent physical examination during the same period of time were enrolled as the control group. The mRNA expression of miR-17-5p in peripheral blood was measured and compared between the two groups. Human renal podocytes were transfected with antisense oligonucleotide recombinant plasmid containing miR-17-5p (inhibition group) or control vector containing nonsense random sequence (negative control group), and untreated human renal podocytes were used as the blank group. These groups were compared in terms of cell apoptosis and the mRNA and protein expression of miR-17-5p, ActA, and Smads after transfection.@*RESULTS@#The NS group had a significantly higher level of miR-17-5p in peripheral blood than the control group (P<0.001). Compared with the blank and negative control groups, the inhibition group had significantly lower apoptosis rate and relative mRNA expression of miR-17-5p and significantly higher relative mRNA and protein expression of ActA, Smad2, and Smad3 (P<0.001).@*CONCLUSIONS@#There is an increase in the content of miR-17-5p in peripheral blood in children with NS. Low expression of miR-17-5p can inhibit the apoptosis of human renal podocytes, which may be associated with the upregulation of the mRNA and protein expression of ActA, Smad2 and Smad3.

Effect and molecular mechanism of interferon-α on podocyte apoptosis induced by hepatitis B virus X protein / 中国当代儿科杂志

OBJECTIVE@#To investigate the effect and molecular mechanism of interferon-α (INF-α) on the apoptosis of the mouse podocyte cell line MPC5 induced by hepatitis B virus X (HBx) protein.@*METHODS@#MPC5 cells were transfected with the pEX plasmid carrying the HBx gene. RT-PCR was used to measure the mRNA expression of HBx at different time points. MPC5 cells were divided into 4 groups: control group (MPC5 cells cultured under normal conditions), INF-α group (MPC5 cells cultured with INF-α), HBx group (MPC5 cells induced by HBx), and HBx+INF-α group (MPC5 cells induced by HBx and cultured with INF-α). After 48 hours of intervention under different experimental conditions, flow cytometry was used to measure the apoptosis of MPC5 cells, and quantitative real-time PCR and Western blot were used to measure the mRNA and protein expression of slit diaphragm-related proteins (nephrin, CD2AP, and synaptopodin) and the cytoskeleton-related protein transient receptor potential cation channel 6 (TRPC6).@*RESULTS@#MPC5 cells transfected by pEX-HBx had the highest expression of HBx mRNA at 48 hours after transfection (P<0.05). Compared with the control, INF-α and HBx+INF-α groups, the HBx group had a significant increase in the apoptosis rate of MPC5 cells (P<0.05). Compared with the control and INF-α groups, the HBx group had significant reductions in the mRNA and protein expression of nephrin, synaptopodin, and CD2AP and significant increases in the mRNA and protein expression of TRPC6 (P<0.05). Compared with the HBx group, the HBx+INF-α group had significant increases in the mRNA and protein expression of nephrin, synaptopodin, and CD2AP and significant reductions in the mRNA and protein expression of TRPC6 (P<0.05).@*CONCLUSIONS@#INF-α can inhibit the apoptosis of podocytes induced by HBx, possibly through improving the abnormal expression of slit diaphragm-related proteins (CD2AP, nephrin, and synaptopodin) and cytoskeleton-related protein (TRPC6) induced by HBx.

Triptolide, A Potential Autophagy Modulator / 中国结合医学杂志

As a major active component extracted from traditional Chinese herb Tripterygium wilfordii Hook F, triptolide exhibits multiple pharmacological effects. Autophagy is an evolutionary conserved intracellular catabolic process involved in cytoplasmic materials degradation. Autophagic dysfunction contributes to the pathologies of many human diseases, which makes it a promising therapeutic target. Recent studies have shown that triptolide exerts neuroprotection, anti-tumor activities, organ toxicity, and podocyte protection by modulating autophagy. This article highlights the current information on triptolide-modulated autophagy, analyzes the possible pathways involved, and describes the crosstalk between autophagy and apoptosis modulated by triptolide, in hope of providing implications for the roles of autophagy in pharmacological effects of triptolide and expanding its novel usage as an autophagy modulator.

Genetic Basis of Steroid Resistant Nephrotic Syndrome

Steroid-resistant nephrotic syndrome (SRNS) has long been a challenge for clinicians due to its poor responsiveness to immunosuppressants, and rapid progression to end-stage renal disease. Identifying a monogenic cause for SRNS may lead to a better understanding of podocyte structure and function in the glomerular filtration barrier. This review focuses on genes associated with slit diaphragm, actin cytoskeleton, transcription factors, nucleus, glomerular basement membrane, mitochondria, and other proteins that affect podocyte biology.

Mesenchymal Stem Cells Ameliorate Renal Inflammation in Adriamycin-induced Nephropathy

Mesenchymal stem cells (MSCs) ameliorate the renal injury in Adriamycin (ADR)-induced nephropathy, but the mechanisms underlying their efficacy remain incompletely understood. In this study, we demonstrated that MSCs increased the survival, recovered body weight loss, and decreased proteinuria and serum creatinine levels in ADR-treated mice. MSCs also prevented podocyte damage and renal fibrosis by decreasing the expression of fibronectin, collagen 1α1, and α-smooth muscle actin. From a mechanistic perspective, MSCs inhibited renal inflammation by lowering the expression of CCL4, CCL7, CCL19, IFN-α/β, TGF-β, TNF-α, and chitinase 3-like 1. In summary, our data demonstrate that MSCs improve renal functions by inhibiting renal inflammation in ADR-induced nephropathy.

Pathogenesis of Minimal Change Nephrotic Syndrome: A Review of the Underlying Molecular Mechanisms

Nephrotic syndrome (NS) is the most common glomerular disorder in childhood, and a vast majority of cases are idiopathic. The precise cause of this common childhood disease is not fully elucidated despite significant advancements in our understanding of podocyte biology. Idiopathic NS has been considered “a disorder of T-cell function” mediated by a circulating factor that alters podocyte function resulting in massive proteinuria since the last four decades. Several circulatory factors released from T-cells are considered to be involved in pathophysiology of NS; however, a single presumptive factor has not been defined yet. Extended evidence obtained by advances in the pathobiology of podocytes has implicated podocytes as critical regulator of glomerular protein filtration and podocytopathy. The candidate molecules as pathological mediators of steroid-dependent NS are CD80 (also known as B7-1), hemopexin, and angiopoietin-like 4. The “two-hit” hypothesis proposes that the expression of CD80 on podocytes and ineffective inhibition of podocyte CD80 due to regulatory T-cell dysfunction or impaired autoregulation by podocytes results in NS. Recent studies suggest that not only T cells but also other immune cells and podocytes are involved in the pathogenesis of MCNS.

Relationship between podocyte injury and macrophage infiltration in renal tissues of patients with lupus nephritis / 北京大学学报(医学版)

OBJECTIVE@#To investigate the relationship between the expression of nephrin and the infiltration of macrophages in renal tissues in patients with lupus nephritis (LN), and to provide the evidence of potential mechanism of podocyte injury in LN.@*METHODS@#In the study, 60 patients who were first diagnosed with LN by pathology were selected including 38 active LN patients with r-SLEDAI≥4, and another 10 patients of normal renal tissue were excised as a normal control group. The renal tissue and podocyte injury were observed through light and transmission electron microscope. The expression of nephrin and the infiltration of macrophages (CD68+cells) in the renal tissue of the 60 LN patients and 10 normal cases were detected by immunohistochemical and immunofluorescence method. Different statistical analysis methods were used to analyze the correlation between the variables. Variance analysis was used for comparison among the groups, while LSD test was used for comparison between every two groups. Pearson correlation analysis was used to analyze the correlation between the variables.@*RESULTS@#(1)Of all the LN patients, 24 h urinary protein [(3.94±1.76) vs. (1.56±0.68), P<0.05], erythrocyte sedimentation rate (ESR) [(79.83±6.3) vs. (40.1±10.5), P<0.05] and serum creatinine [(106.58±14.9) vs. (79.1±9.89), P<0.05] were significantly increased in active group than those in inactive group, while C3 [(0.34±0.12) vs. (0.78±0.11), P<0.05], C4 [(0.07±0.04) vs. (0.17±0.10), P<0.05 ] and eGFR [(62.42±5.16) vs. (81.33±4.53), P<0.05] were significantly decreased in active group. (2)Compared with the normal control group, the expression of nephrin in renal tissue of the LN patients was significantly decreased, and the expression of nephrin in the active patients was significantly lower than that in inactive group (P<0.05). (3)Compared with the normal control group, the number of infiltrated macrophages in the LN patients was significantly increased, especially in the active patients (P<0.05). Macrophages were mainly found in glomeruli. (4)There was a significant negative correlation between the expression of nephrin and macrophage infiltration in renal tissues of the LN patients (r=0.761, P<0.001).@*CONCLUSION@#Macrophage infiltration in renal tissues may be one of the potential mechanisms of podocyte injury in lupus nephritis.

Long term follow up of biomarkers of podocyte damage and renal function in patients with and without preeclampsia / Seguimento de longo prazo com biomarcadores de dano podocitário e função renal em pacientes com e sem pré-eclâmpsia

ABSTRACT Introduction: preeclampsia can be associated with future renal disease. Objectives: To measure changes in renal function overtime in patients with preeclampsia. Methods: urine and serum samples from eleven patients with preeclampsia and eight patients with a normal pregnancy were obtained during pregnancy, postpartum, and 3 years after delivery. Urine podocalyxin, protein, and serum creatinine were measured. Results: after 3 years, there were no significant differences in urinary podocalyxin in patients with or without preeclampsia: 4.34 ng/mg [2.69, 8.99] vs. 7.66 ng/mg [2.35, 13], p = 0.77. The same applied to urinary protein excretion: 81.5 mg/g [60.6, 105.5] vs. 43.2 mg/g [20.9, 139.3] p = 0.23. Serum creatinine was 0.86 mg/dL [0.7, 0.9] vs. 0.8 mg/dL [0.68, 1] p = 0.74 in those with and without preeclampsia. In normal patients, urinary podocalyxin decreased from 54.4 ng/mg [34.2, 76.9] during pregnancy to 7.66 ng/mg [2.35, 13] three years after pregnancy, p = 0.01. Proteinuria decreased from 123.5 mg/g [65.9, 194.8] to 43.2 mg/g [20.9, 139.3], p = 0.12. In preeclampsia patients, urinary podocalyxin decreased from 97.5 ng/mg [64.9, 318.4] during pregnancy to 37.1 ng/mg within one week post-partum [21.3, 100.4] p = 0.05 and 4.34 ng/mg [2.69, 8.99] three years after, p = 0.003. Proteinuria was 757.2 mg/g [268.4, 5031.7] during pregnancy vs. 757.2 mg/g [288.2, 2917] postpartum, p = 0.09 vs. 81.5 mg/g [60.6, 105.5] three years later, p = 0.01. Two patients still had proteinuria after 3 years. Conclusions: in preeclampsia patients, postpartum urinary podocalyxin decreased before proteinuria. After three years, serum creatinine, urinary podocalyxin, and protein tended to normalize, although some patients still had proteinuria.

RESUMO Introdução: a pré-eclâmpsia pode estar associada à doença renal no futuro. Objetivos: medir mudanças na função renal ao longo do tempo em pacientes com pré-eclâmpsia. Métodos: amostras de urina e soro de onze pacientes com pré-eclâmpsia e oito pacientes com gravidez normal foram obtidas durante a gravidez, pós-parto e 3 anos após o parto. Medimos podocalixina na urina, proteína e creatinina sérica. Resultados: após 3 anos, não houve diferenças significativas na podocalixina urinária em pacientes com ou sem pré-eclâmpsia: 4,34 ng/mg [2,69, 8,99] versus 7,66 ng/mg [2,35, 13], p = 0,77. O mesmo se aplicou à excreção urinária de proteínas: 81,5 mg/g [60,6, 105,5] vs. 43,2 mg/g [20,9, 139,3] p = 0,23. A creatinina sérica foi de 0,86 mg/dL [0,7, 0,9] vs. 0,8 mg/dL [0,68, 1] p = 0,74 naqueles com e sem pré-eclâmpsia. Em pacientes normais, a podocalixina urinária diminuiu de 54,4 ng/mg [34,2, 76,9] durante a gestação para 7,66 ng/mg [2,35, 13] três anos após a gravidez, p = 0,01. A proteinúria diminuiu de 123,5 mg/g [65,9, 194,8] para 43,2 mg/g [20,9, 139,3], p = 0,12. Em pacientes com pré-eclâmpsia, a podocalixina urinária diminuiu de 97,5 ng/mg [64,9, 318,4] durante a gravidez para 37,1 ng/mg em uma semana de pós-parto [21,3, 100,4] p = 0,05 e 4,34 ng/mg [2,69, 8,99] três anos depois, p = 0,003. A proteinúria foi de 757,2 mg/g [268.4, 5031.7] durante a gravidez vs. 757,2 mg/g [288.2, 2917] pós-parto, p = 0.09 vs. 81.5 mg/g [60.6, 105.5] três anos depois, p = 0.01. Dois pacientes ainda apresentavam proteinúria após 3 anos. Conclusões: em pacientes com pré-eclâmpsia, a podocalixina urinária pós-parto diminuiu antes da proteinúria. Após três anos, a creatinina sérica, a podocalixina urinária e a proteína tenderam a se normalizar, embora alguns pacientes ainda tivessem proteinúria.

APOL1 risk variants and kidney disease: what we know so far / Variantes de risco APOL1 e doença renal: o que sabemos até agora

ABSTRACT There are striking differences in chronic kidney disease between Caucasians and African descendants. It was widely accepted that this occurred due to socioeconomic factors, but recent studies show that apolipoprotein L-1 (APOL1) gene variants are strongly associated with focal segmental glomerulosclerosis, HIV-associated nephropathy, hypertensive nephrosclerosis, and lupus nephritis in the African American population. These variants made their way to South America trough intercontinental slave traffic and conferred an evolutionary advantage to the carries by protecting against forms of trypanosomiasis, but at the expense of an increased risk of kidney disease. The effect of the variants does not seem to be related to their serum concentration, but rather to local action on the podocytes. Risk variants are also important in renal transplantation, since grafts from donors with risk variants present worse survival.

RESUMO Existem importantes diferenças na doença renal crônica entre caucasianos e afrodescendentes. Foi amplamente aceito que isso ocorreu devido a fatores socioeconômicos, mas estudos recentes mostraram que as variantes gênicas da apolipoproteína L-1 (APOL1) estão fortemente associadas à glomeruloesclerose segmentar e focal, nefropatia associada ao HIV, nefroesclerose hipertensiva e nefrite lúpica na população afrodescendente. Essas variantes chegaram à América do Sul através do tráfico intercontinental de escravos, e proporcionaram uma vantagem evolutiva aos portadores, protegendo contra formas de tripanossomíase, mas à custa de um maior risco de doença renal. O efeito das variantes não parece estar relacionado à sua concentração sérica, mas sim à sua ação local sobre os podócitos. Variantes de risco também são importantes no transplante renal, já que enxertos de doadores com variantes de risco apresentam pior sobrevida.