[Jianpi Zishen granule inhibits podocyte autophagy in systemic lupus erythematosus: a network pharmacology and clinical study].

OBJECTIVE: To explore the therapeutic mechanism of Jianpi Zishen (JPZS) granules for systemic lupus erythematosus(SLE) in light of podocyte autophagy regulation. METHODS: TCMSP, GeneCards, OMIM, and TTD databases were used to obtain the targets of JPZS granules, SLE, and podocyte autophagy. The protein-protein interaction network was constructed using Cytoscape, and the key active ingredients and targets were screened for molecular docking. In the clinical study, 46 patients with SLE were randomized into two groups to receive baseline treatment with prednisone acetate and mycophenolate mofetil (control group) and additional treatment with JPZS granules (observation group) for 12 weeks, with 10 healthy volunteers as the healthy control group. Urinary levels of nephrin and synaptopodin of the patients were detected with ELISA. Western blotting was performed to determine peripheral blood levels of p-JAK1/JAK1, p-STAT1/STAT1, LC3II/LC3I, and p62 proteins of the participants. RESULTS: Four key active ingredients and 5 core target genes (STAT1, PIK3CG, MAPK1, PRKCA, and CJA1) were obtained, and enrichment analysis identified the potentially involved signaling pathways including AGE-RAGE, JAK/STAT, EGFR, and PI3K/Akt. Molecular docking analysis showed that STAT1 was the most promising target protein with the highest binding activity, suggesting its role as an important mediator for signal transduction after JPZS granule treatment. In the 43 SLE patients available for analysis, treatment with JPZS granule significantly reduced serum levels of p-JAK1/JAK1, p-STAT1/STAT1, and LC3II/LC3I (P < 0.05 or 0.01), increased the protein level of P62 (P < 0.05), and reduced urinary levels of nephrin and synaptopodin (P < 0.05). CONCLUSION: The therapeutic effect of JPZS granules on SLE is mediated probably by coordinated actions of quercetin, kaempferol, ß-sitosterol, and isorhamnetin on their target gene STAT1 to inhibit the JAK/STAT pathway, thus suppressing autophagy and alleviating podocyte injuries in SLE.

"Qi Nan" agarwood restores podocyte autophagy in diabetic kidney disease by targeting EGFR signaling pathway.

BACKGROUND: Diabetic kidney disease (DKD) is a microvascular complication of diabetes mellitus, contributing to end-stage renal disease with limited treatment options. The development of DKD is attributed to podocyte injury resulting from abnormal podocyte autophagy. Consequently, the restoration of podocyte autophagy is deemed a practicable approach in the treatment of DKD. METHODS: Diabetic mice were induced by streptozotocin and high-fat diet feeding. Following 8 weeks of "QN" agarwood treatment, metrics such as albuminuria, serum creatinine (Scr), and blood urea nitrogen (BUN) were evaluated. Renal histological lesions were evaluated by H&E, PAS, Masson, and Sirius red staining. Evaluation of the effects of "QN" agarwood on renal inflammation and fibrosis in DKD mice through WB, q-PCR, and IHC staining analysis. Cytoscape 3.7.1 was used to construct a PPI network. With the DAVID server, the gene ontology (GO) functional annotation and the Kyoto encyclopedia of genes and genomes (KEGG) signaling pathways of the target enrichment were performed. Molecular docking and binding affinity calculations were conducted using AutoDock, while PyMOL software was employed for visualizing the docking results of active compounds and protein targets. RESULTS: The results of this study show that "QN" agarwood reduced albuminuria, Scr, and BUN in DKD mice, and improved the renal pathological process. Additionally, "QN" agarwood was observed to downregulate the mRNA and protein expression levels of pro-inflammatory and pro-fibrotic factors in the kidneys of DKD mice. Network pharmacology predicts that "QN" agarwood modulates the epidermal growth factor receptor (EGFR) signaling pathway. "QN" agarwood can increase the expression of LC3B and Nphs1 in DKD mice while reducing the expression of EGFR. CONCLUSION: The present study demonstrated that "QN" agarwood ameliorated renal injury in DKD by targeting EGFR and restoring podocyte autophagy.

Xuebijing injection and its bioactive components alleviate nephrotic syndrome by inhibiting podocyte inflammatory injury.

Xuebijing injection (XBJ) is widely used to treat nephrotic syndrome (NS) in clinic, but its bioactive components and therapeutic mechanism are still unclear. In this study, the bioactive components of XBJ were determined by ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS). The therapeutic effect of XBJ on NS was evaluated in BALB/c mice induced by adriamycin (ADR, 10 mg/kg) via a single tail vein. The protective effect of XBJ and its bioactive components on podocytes was demonstrated using mouse podocytes (MPC-5) induced by lipopolysaccharide (LPS, 4 µg/mL). The results show that 33 components of XBJ were identified. Furthermore, 12 bioactive components were detected in blood, including protocatechuic acid, salvianolic acid C, benzoyloxypaeoniflorin, danshensu, salvianolic acid A, salvianolic acid B, catechin, caffeic acid, galloylpaeoniflorin, oxypaeoniflorin, hydroxysafflor yellow A, rosmarinic acid. The relative content (%) of the bioactive components were 59.32, 16.01, 9.97, 9.73, 8.72, 8.31, 7.92, 6.54, 1.54, 1.30, 0.68 and 0.59 in this order. After XBJ treatment, the renal function, hyperlipidemia and renal pathological damage were improved in NS model mice. Moreover, the levels of nephrin and desmin which are functional proteins in podocytes were reversed, and the levels of pro-inflammatory factors were reduced by XBJ. Interestingly, protocatechuic acid and salvianolic acid C also showed good protective effects on podocyte function and reduced the level of inflammation in LPS-induced MPC-5. The study is the first time to elucidate the bioactive components of XBJ and its potential therapeutic mechanism for treating NS by protecting podocyte function.

Not an immune cell, but they may act like one-cells with immune properties outside the immune system.

The cells presented in this work are not classified as cells that make up the immune system. They, however, present functions and molecules, which are characteristic of immune cells. These characteristic functions are, for example, sensing threat, performing phagocytosis, presentation of foreign antigens, cytokine release or enhancing immune memory. The enlisted immune response mechanisms are carried out by the possession of molecules such as Toll-like receptors, receptors for the Fc fragment of IgG, major histocompatibility complex class II molecules, costimulatory CD80/CD86 proteins and molecules needed for NLRP3 (NOD-like family pyrin domain containing 3) inflammasome activation. Thanks to these properties, the described nonimmune cells play an important role in the local immune response and support of the entire body in the fight against pathogens. They constitute the first line of defense of tissues and organs against pathogens and molecules recognized as harmful. The cells described in this article are particularly important in immunologically privileged places (e.g. the Bowman's capsule in the kidney), where "typical" immune cells normally do not have access. In this paper, we present immune-like functions and molecule suites of resident kidney cells (podocytes and mesangial cells), cochlear resident cells, fibrocytes and fibroblasts, as well as some stem cells (mesenchymal stem cells and umbilical cord Wharton's jelly-derived cells).

GDF-15 Suppresses Puromycin Aminonucleoside-Induced Podocyte Injury by Reducing Endoplasmic Reticulum Stress and Glomerular Inflammation.

GDF15, also known as MIC1, is a member of the TGF-beta superfamily. Previous studies reported elevated serum levels of GDF15 in patients with kidney disorder, and its association with kidney disease progression, while other studies identified GDF15 to have protective effects. To investigate the potential protective role of GDF15 on podocytes, we first performed in vitro studies using a Gdf15-deficient podocyte cell line. The lack of GDF15 intensified puromycin aminonucleoside (PAN)-triggered endoplasmic reticulum stress and induced cell death in cultivated podocytes. This was evidenced by elevated expressions of Xbp1 and ER-associated chaperones, alongside AnnexinV/PI staining and LDH release. Additionally, we subjected mice to nephrotoxic PAN treatment. Our observations revealed a noteworthy increase in both GDF15 expression and secretion subsequent to PAN administration. Gdf15 knockout mice displayed a moderate loss of WT1+ cells (podocytes) in the glomeruli compared to wild-type controls. However, this finding could not be substantiated through digital evaluation. The parameters of kidney function, including serum BUN, creatinine, and albumin-creatinine ratio (ACR), were increased in Gdf15 knockout mice as compared to wild-type mice upon PAN treatment. This was associated with an increase in the number of glomerular macrophages, neutrophils, inflammatory cytokines, and chemokines in Gdf15-deficient mice. In summary, our findings unveil a novel renoprotective effect of GDF15 during kidney injury and inflammation by promoting podocyte survival and regulating endoplasmic reticulum stress in podocytes, and, subsequently, the infiltration of inflammatory cells via paracrine effects on surrounding glomerular cells.

Identification of Four Mouse FcRn Splice Variants and FcRn-Specific Vesicles.

Research into the neonatal Fc receptor (FcRn) has increased dramatically ever since Simister and Mostov first purified a rat version of the receptor. Over the years, FcRn has been shown to function not only as a receptor that transfers immunity from mother to fetus but also performs an array of different functions that include transport and recycling of immunoglobulins and albumin in the adult. Due to its important cellular roles, several clinical trials have been designed to either inhibit/enhance FcRn function or develop of non-invasive therapeutic delivery system such as fusion of drugs to IgG Fc or albumin to enhance delivery inside the cells. Here, we report the accidental identification of several FcRn alternatively spliced variants in both mouse and human cells. The four new mouse splice variants are capable of binding immunoglobulins' Fc and Fab portions. In addition, we have identified FcRn-specific vesicles in which immunoglobulins and albumin can be stored and that are involved in the endosomal-lysosomal system. The complexity of FcRn functions offers significant potential to design and develop novel and targeted therapeutics.

Melittin induces autophagy to alleviate chronic renal failure in 5/6-nephrectomized rats and angiotensin II-induced damage in podocytes.

BACKGROUND/OBJECTIVES: Chronic renal failure (CRF) is a complex pathological condition that lacks a cure. Certain Chinese medicines, such as melittin, a major component in bee venom, have shown efficacy in treating CRF patients. On the other hand, the mechanisms underlying the therapeutic effects of melittin are unclear. MATERIALS/METHODS: A 5/6 nephrectomy model (5/6 Nx) of renal failure was established on rats for in vivo assays, and mouse podocyte clone 5 (MPC5) mouse podocyte cells were treated with angiotensin II (AngII) to establish an in vitro podocyte damage model. The 24-h urine protein, serum creatinine, and blood urea nitrogen levels were evaluated after one, 2, and 4 weeks. Hematoxylin and eosin staining, Masson staining, and periodic acid-Schiff staining were used to examine the pathological changes in kidney tissues. A cell counting kit 8 assay was used to assess the cell viability. Reverse transcription polymerase chain reaction and Western blot were used to assess the mRNA and protein levels in the cells, respectively. RESULTS: In the rat 5/6 Nx, melittin reduced the 24-h urinary protein excretion and the serum creatinine and blood urea nitrogen levels. Furthermore, the renal pathology was improved in the melittin-treated 5/6 Nx rats. Melittin promoted podocin, nephrin, Beclin 1, and the LC3II/LC3I ratio and inhibited phosphorylated mammalian target of rapamycin (mTOR)/mTOR in 5/6 Nx-induced rats and AngII-induced MPC5 mouse podocyte cells. Moreover, inhibiting autophagy with 3-MA weakened the effects of melittin on podocin, nephrin, and the LC3II/LC3I ratio in podocytes. CONCLUSION: Melittin may offer protection against kidney injury, probably by regulating podocyte autophagy. These results provide the theoretical basis for applying melittin in CRF therapy.

Urine-derived podocytes from steroid resistant nephrotic syndrome patients as a model for renal-progenitor derived extracellular vesicles effect and drug screening.

Background: Personalized disease models are crucial for assessing the specific response of diseased cells to drugs, particularly novel biological therapeutics. Extracellular vesicles (EVs), nanosized vesicles released by cells for intercellular communication, have gained therapeutic interest due to their ability to reprogram target cells. We here utilized urinary podocytes obtained from children affected by steroid-resistant nephrotic syndrome with characterized genetic mutations as a model to test the therapeutic potential of EVs derived from kidney progenitor cells. Methods: EVs were isolated from kidney progenitor cells (nKPCs) derived from the urine of a preterm neonate. Three lines of urinary podocytes obtained from nephrotic patients' urine and a line of Alport patient podocytes were characterized and used to assess albumin permeability in response to various drugs or to nKPC-EVs. RNA sequencing was conducted to identify commonly modulated pathways. Results: Podocytes appeared unresponsive to pharmacological treatments, except for a podocyte line demonstrating responsiveness, in alignment with the patient's clinical response at 48 months. At variance, treatment with the nKPC-EVs was able to significantly reduce permeability in all the steroid-resistant patients-derived podocytes as well as in the line of Alport-derived podocytes. RNA sequencing of nKPC-EV-treated podocytes revealed the common upregulation of two genes (small ubiquitin-related modifier 1 (SUMO1) and Sentrin-specific protease 2 (SENP2)) involved in the SUMOylation pathway, a process recently demonstrated to play a role in slit diaphragm stabilization. Gene ontology analysis on podocyte expression profile highlighted cell-to-cell adhesion as the primary upregulated biological activity in treated podocytes. Conclusions: nKPCs emerge as a promising non-invasive source of EVs with potential therapeutic effects on podocyte dysfunction. Furthermore, our findings suggest the possibility of establishing a non-invasive in vitro model for screening regenerative compounds on patient-derived podocytes.

Podocyte Ercc1 is indispensable for glomerular integrity.

As life expectancy continues to increase, age-related kidney diseases are becoming more prevalent. Chronic kidney disease (CKD) is not only a consequence of aging but also a potential accelerator of aging process. Here we report the pivotal role of podocyte ERCC1, a DNA repair factor, in maintaining glomerular integrity and a potential effect on multiple organs. Podocyte-specific ERCC1-knockout mice developed severe proteinuria, glomerulosclerosis, and renal failure, accompanied by a significant increase in glomerular DNA single-strand breaks (SSBs) and double-strand breaks (DSBs). ERCC1 gene transfer experiment in the knockout mice attenuated proteinuria and glomerulosclerosis with reduced DNA damage. Notably, CD44+CD8+ memory T cells, indicative of T-cell senescence, were already elevated in the peripheral blood of knockout mice at 10 weeks old. Additionally, levels of senescence-associated secretory phenotype (SASP) factors were significantly increased in both the circulation and multiple organs of the knockout mice. In older mice and human patients, we observed an accumulation of DSBs and an even greater buildup of SSBs in glomeruli, despite no significant reduction in ERCC1 expression with age in mice. Collectively, our findings highlight the crucial role of ERCC1 in repairing podocyte DNA damage, with potential implications for inflammation in various organs.

Reversible and monitorable nephrotoxicity in rats by the novel potent transcriptional enhanced associate domain (TEAD) inhibitor, K-975.

The Hippo pathway plays an important role in the growth, development, and regeneration of cells and organs. Transcriptional enhanced associate domain (TEAD), a transcription activator of the Hippo pathway, forms the complex with a transcriptional coactivator yes-associated protein (YAP) or a transcriptional coactivator PDZ-binding motif (TAZ). Their excessive activations are involved in carcinogenesis such as malignant pleural mesothelioma (MPM), and thus inhibition of the TEAD complex is expected to have potent anticancer activity against MPM. On the other hand, YAP or TAZ conditional knockout mice have been reported to show abnormal findings in various tissues, including the kidney, liver, and lung. In the present study, we evaluated the systemic toxicity of K-975, a novel TEAD inhibitor, in rats. When K-975 was administered orally to rats for 1 week, proteinuria suggestive of nephrotoxicity was observed. Electron microscopy revealed that K-975 at 300 mg/kg induced glomerular podocyte foot process effacement. After a 2-week recovery period, proteinuria with foot process effacement was recovered completely. Urinalysis and urinary biomarker evaluation suggested that the urinary albumin index (urinary albumin/urinary creatinine) was the most sensitive marker for detecting K-975-induced nephrotoxicity. After 3 cycles of 1-week administration followed by 2-week recovery periods, nephrotoxicity was reversible; however, incomplete reversibility was observed in rats with severe proteinuria. In conclusion, this study revealed that in rats, oral K-975 treatment induced severe proteinuria by podocyte foot process effacement, which was reversible and monitorable by the urinary albumin index, suggesting important information for developing K-975 as an anticancer drug.

Colony stimulating factor-1 receptor drives glomerular parietal epithelial cell activation in focal segmental glomerulosclerosis.

Parietal epithelial cells (PECs) are kidney progenitor cells with similarities to a bone marrow stem cell niche. In focal segmental glomerulosclerosis (FSGS) PECs become activated and contribute to extracellular matrix deposition. Colony stimulating factor-1 (CSF-1), a hematopoietic growth factor, acts via its specific receptor, CSF-1R, and has been implicated in several glomerular diseases, although its role on PEC activation is unknown. Here, we found that CSF-1R was upregulated in PECs and podocytes in biopsies from patients with FSGS. Through in vitro studies, PECs were found to constitutively express CSF-1R. Incubation with CSF-1 induced CSF-1R upregulation and significant transcriptional regulation of genes involved in pathways associated with PEC activation. Specifically, CSF-1/CSF-1R activated the ERK1/2 signaling pathway and upregulated CD44 in PECs, while both ERK and CSF-1R inhibitors reduced CD44 expression. Functional studies showed that CSF-1 induced PEC proliferation and migration, while reducing the differentiation of PECs into podocytes. These results were validated in the Adriamycin-induced FSGS experimental mouse model. Importantly, treatment with either the CSF-1R-specific inhibitor GW2580 or Ki20227 provided a robust therapeutic effect. Thus, we provide evidence of the role of the CSF-1/CSF-1R pathway in PEC activation in FSGS, paving the way for future clinical studies investigating the therapeutic effect of CSF-1R inhibitors on patients with FSGS.

Rutaecarpine protects podocytes in diabetic kidney disease by targeting VEGFR2/NLRP3-mediated pyroptosis.

OBJECTIVE: Diabetic kidney disease (DKD) is the most common cause of the end-stage renal disease, which has limited treatment options. Rutaecarpine has anti-inflammatory effects, however, it has not been studied in DKD. Pyroptosis is a newly discovered mode of podocyte death related to inflammation. This study aimed to explore whether Rutaecarpine can ameliorate DKD and to clarify its possible mechanism. METHODS: In this study, we investigated the effects of Rutaecarpine on DKD using diabetic mice model (db/db mice) and high glucose (HG)-stimulated mouse podocyte clone 5 (MPC5) cells. Quantitative reverse transcription polymerase chain reaction and western blot were performed to detect the related gene and protein levels. We applied pharmacological prediction, co-immunoprecipitation assay, cellular thermal shift assay, surface plasmon resonance to find the target and pathway of the substances. Gene knockdown experiments confirmed this view in HG-stimulated MPC5 cells. RESULTS: Rutaecarpine significantly reduced proteinuria, histopathological damage, and pyroptosis of podocytes in a dose-dependent manner in db/db mice. Rutaecarpine also protected high glucose induced MPC5 injury in vitro experiments. Mechanistically, Rutaecarpine can inhibit pyroptosis in HG-stimulated MPC5 by reducing the expression of VEGFR2. VEGFR2 is a target of Rutaecarpine in MPC5 cells and directly binds to the pyroptosis initiation signal, NLRP3. VEGFR2-knockdown disrupted the beneficial effects of Rutaecarpine in HG-stimulated MPC5 cells. CONCLUSION: Rutaecarpine inhibits renal inflammation and pyroptosis through VEGFR2/NLRP3 pathway, thereby alleviating glomerular podocyte injury. These findings highlight the potential of Rutaecarpine as a novel drug for DKD treatment.

IFI16 Is Indispensable for Promoting HIF-1α-Mediated APOL1 Expression in Human Podocytes under Hypoxic Conditions.

Genetic variants in the protein-coding regions of APOL1 are associated with an increased risk and progression of chronic kidney disease (CKD) in African Americans. Hypoxia exacerbates CKD progression by stabilizing HIF-1α, which induces APOL1 transcription in kidney podocytes. However, the contribution of additional mediators to regulating APOL1 expression under hypoxia in podocytes is unknown. Here, we report that a transient accumulation of HIF-1α in hypoxia is sufficient to upregulate APOL1 expression in podocytes through a cGAS/STING/IRF3-independent pathway. Notably, IFI16 ablation impedes hypoxia-driven APOL1 expression despite the nuclear accumulation of HIF-1α. Co-immunoprecipitation assays indicate no direct interaction between IFI16 and HIF-1α. Our studies identify hypoxia response elements (HREs) in the APOL1 gene enhancer/promoter region, showing increased HIF-1α binding to HREs located in the APOL1 gene enhancer. Luciferase reporter assays confirm the role of these HREs in transcriptional activation. Chromatin immunoprecipitation (ChIP)-qPCR assays demonstrate that IFI16 is not recruited to HREs, and IFI16 deletion reduces HIF-1α binding to APOL1 HREs. RT-qPCR analysis indicates that IFI16 selectively affects APOL1 expression, with a negligible impact on other hypoxia-responsive genes in podocytes. These findings highlight the unique contribution of IFI16 to hypoxia-driven APOL1 gene expression and suggest alternative IFI16-dependent mechanisms regulating APOL1 gene expression under hypoxic conditions.

Transcriptomic profile of human iPSC-derived podocyte-like cells exposed to a panel of xenobiotics.

Podocytes play a critical role in the formation and maintenance of the glomerular filtration barrier and injury to these cells can lead to a breakdown of the glomerular barrier causing permanent damage leading to progressive chronic kidney disease. Matured podocytes have little proliferative potential, which makes them critical cells from a health perspective, but also challenging cells to maintain in vitro. Differentiating podocyte-like cells from induced pluripotent stem cells (iPSC) provides a novel and continuous source of cells. Here, we investigated the effect of a 24-h exposure to eight compounds, including the known glomerular toxins doxorubicin and pamidronate, on transcriptomic alterations in iPSC derived podocytes. Doxorubicin (50 nM), pamidronate (50 µM), sodium arsenite (10 µM), and cyclosporine A (15 µM) had a strong impact on the transcriptome, gentamicin (450 µg/ml), lead chloride (15 µM) and valproic acid (500 µM) had a mild impact and busulfan (50 µM) exhibited no impact. Gene alterations and pathways analysis provided mechanistic insight for example, doxorubicin exposure affected the p53 pathway and dedifferentiation, pamidronate activated several pathways including HIF1alpha and sodium arsenite up-regulated oxidative stress and metal responses. The results demonstrate the applicability of iPSC derived podocytes for toxicological and mechanistic investigations.

Precision medicine for focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is one of the common causes of nephrotic syndrome in adults and children worldwide. FSGS consists of a group of kidney diseases classified based on specific histopathological features. The current classification of FSGS makes it difficult to distinguish individual differences in pathogenesis, disease progression, and response to treatment. In recent years, the spread of next-generation sequencing, updates in biological techniques, and improvements of treatment have changed our understanding of FSGS. In this review, we will discuss the use of genetic testing in patients with FSGS, explore its clinical significance from a genetic identification perspective, and introduce several new biomarkers, that may help in the early diagnosis of FSGS and guide the development of specific or targeted therapies, so as to understand the biological characteristics in FSGS. This will certainly help develop more effective and safer treatments and advance precision medicine.

Urinary podocyte markers in diabetic kidney disease.

Podocytes are involved in maintaining kidney function and are a major focus of research on diabetic kidney disease (DKD). Urinary biomarkers derived from podocyte fragments and molecules have been proposed for the diagnosis and monitoring of DKD. Various methods have been used to detect intact podocytes and podocyte-derived microvesicles in urine, including centrifugation, visualization, and molecular quantification. Quantification of podocyte-specific protein targets and messenger RNA levels can be performed by Western blotting or enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. At present, many of these techniques are expensive and labor-intensive, all limiting their widespread use in routine clinical tests. While the potential of urinary podocyte markers for monitoring and risk stratification of DKD has been explored, systematic studies and external validation are lacking in the current literature. Standardization and automation of laboratory methods should be a priority for future research, and the added value of these methods to routine clinical tests should be defined.

Nephrotic syndrome sera induce different transcriptomes in podocytes based on the steroid response.

As the molecular mechanism of nephrotic syndrome remains largely undiscovered, patients continue to be exposed to the pros and cons of uniform glucocorticoid treatment. We explored whether the exposure of in vitro-cultivated podocytes to sera from children with steroid-sensitive or steroid-resistant nephrotic syndrome induces differences in gene expression profiles, which could help to elucidate the pathogenesis of the steroid response. Human immortalized podocytes were cultivated with patient sera for 3 days. After cell lysis, RNA extraction, 3'-mRNA libraries were prepared and sequenced. There were 34 significantly upregulated and 14 downregulated genes (fold difference <0.5 and >2.0, respectively, and false discovery rate-corrected p < 0.05) and 22 significantly upregulated and 6 downregulated pathways (false discovery rate-corrected p < 0.01) in the steroid-sensitive (n = 9) versus steroid-resistant group (n = 4). The observed pathways included upregulated redox reactions, DNA repair, mitosis, protein translation and downregulated cholesterol biosynthesis. Sera from children with nephrotic syndrome induce disease subtype-specific transcriptome changes in human podocytes in vitro. However, further exploration of a larger cohort is needed to verify whether clinically distinct types of nephrotic syndrome or disease activity may be differentiated by specific transcriptomic profiles and whether this information may help to elucidate the pathogenesis of the steroid response.

Inhibition of transcriptional coactivator YAP Impairs the expression and function of transcription factor WT1 in diabetic podocyte injury.

Podocyte injury and loss are hallmarks of diabetic nephropathy (DN). However, the molecular mechanisms underlying these phenomena remain poorly understood. YAP (Yes-associated protein) is an important transcriptional coactivator that binds with various other transcription factors, including the TEAD family members (nuclear effectors of the Hippo pathway), that regulate cell proliferation, differentiation, and apoptosis. The present study found an increase in YAP phosphorylation at S127 of YAP and a reduction of nuclear YAP localization in podocytes of diabetic mouse and human kidneys, suggesting dysregulation of YAP may play a role in diabetic podocyte injury. Tamoxifen-inducible podocyte-specific Yap gene knockout mice (YappodKO) exhibited accelerated and worsened diabetic kidney injury. YAP inactivation decreased transcription factor WT1 expression with subsequent reduction of Tead1 and other well-known targets of WT1 in diabetic podocytes. Thus, our study not only sheds light on the pathophysiological roles of the Hippo pathway in diabetic podocyte injury but may also lead to the development of new therapeutic strategies to prevent and/or treat DN by targeting the Hippo signaling pathway.

Hepatitis B virus-targeting sodium taurocholate cotransporting polypeptide mediates HBV infection and damage in human renal podocytes.

Hepatitis B virus (HBV) may directly infect human podocytes (HPCs). However, the mechanism of direct infection is unclear. We found that HPCs express sodium taurocholate cotransporting polypeptide (NTCP), a specific receptor for HBV entry into hepatocytes. Thus, we investigated whether NTCP mediates HBV infection and damage in HPCs and further clarified the specific mechanism. We constructed shRNA-NTCP1,2, shRNA-NC, WT-NTCP, and MUT-NTCP and transfected them into HPCs. HPCs were infected with HBV, and HBV infection markers were detected by enzyme-linked immunosorbent assay (ELISA) and real-time quantitative PCR (RT-qPCR). The functional changes in HPCs were detected by Transwell migration and scratch assays, apoptosis was evaluated by flow cytometry (FCM), and podocytoskeletal proteins (nephrin, CD2AP, and synaptopodin) were determined by western blotting (WB). Compared with the control HPCs, HPCs infected with HBV showed increased levels of HBV infection markers and apoptosis along with decreased podocytoskeletal protein expressions, cell vitality, proliferation, and migration. Compared with the HPCs infected with HBV, the HPCs transfected with HBV + shRNA-NTCP, and HBV + MUT-NTCP showed decreased levels of HBV infection markers and apoptosis along with increased podocytoskeletal protein expressions, cell vitality, proliferation, and migration; the opposite effects were observed in the HPCs transfected with HBV + WT-NTCP. Overall, the changes to NTCP affected the susceptibility of HPCs to HBV and modulated HPC damage and repair. NTCP can mediate direct HBV infection and damage human podocytes, and the NTCP 157-165 locus is the main site of HBV entry. The findings provide a new target and theoretical basis for HBV-associated glomerulonephritis. IMPORTANCE: This study identified for the first time that sodium taurocholate cotransporting polypeptide (NTCP) can mediate HBV direct infection and damage to human podocytes, and the NTCP157-165 locus is the main HBV entry site. The findings provide theoretical support for the pathogenesis of direct infection of HBV with kidney tissue. The findings provide a new target and theoretical basis for the treatment of HBV-related glomerulonephritis (HBV-GN). Blocking NTCP is a new target for the treatment of HBV-GN. We found that tacrolimus, a calcineurin inhibitor that blocks NTCP, can effectively treat HBV-GN. This study also provides a theoretical basis for the effective and safe treatment of immunosuppressant tacrolimus for HBV-GN.

Renal Expression and Localization of the Receptor for (Pro)renin and Its Ligands in Rodent Models of Diabetes, Metabolic Syndrome, and Age-Dependent Focal and Segmental Glomerulosclerosis.

The (pro)renin receptor ((P)RR), a versatile protein found in various organs, including the kidney, is implicated in cardiometabolic conditions like diabetes, hypertension, and dyslipidemia, potentially contributing to organ damage. Importantly, changes in (pro)renin/(P)RR system localization during renal injury, a critical information base, remain unexplored. This study investigates the expression and topographic localization of the full length (FL)-(P)RR, its ligands (renin and prorenin), and its target cyclooxygenase-2 and found that they are upregulated in three distinct animal models of renal injury. The protein expression of these targets, initially confined to specific tubular renal cell types in control animals, increases in renal injury models, extending to glomerular cells. (P)RR gene expression correlates with protein changes in a genetic model of focal and segmental glomerulosclerosis. However, in diabetic and high-fat-fed mice, (P)RR mRNA levels contradict FL-(P)RR immunoreactivity. Research on diabetic mice kidneys and human podocytes exposed to diabetic glucose levels suggests that this inconsistency may result from disrupted intracellular (P)RR processing, likely due to increased Munc18-1 interacting protein 3. It follows that changes in FL-(P)RR cellular content mechanisms are specific to renal disease etiology, emphasizing the need for consideration in future studies exploring this receptor's involvement in renal damage of different origins.