HIF-1 contributes to autophagy activation via BNIP3 to facilitate renal fibrosis in hypoxia in vitro and UUO in vivo.

The molecular basis of renal interstitial fibrosis, a major pathological feature of progressive kidney diseases, remains poorly understood. Autophagy has been implicated in renal fibrosis, but whether it promotes or inhibits fibrosis remains controversial. Moreover, it is unclear how autophagy is activated and sustained in renal fibrosis. The present study was designed to address these questions using the in vivo mouse model of unilateral ureteral obstruction and the in vitro model of hypoxia in renal tubular cells. Both models showed the activation of hypoxia-inducible factor-1 (HIF-1) and autophagy along with fibrotic changes. Inhibition of autophagy with chloroquine reduced renal fibrosis in unilateral ureteral obstruction model, whereas chloroquine and autophagy-related gene 7 knockdown decreased fibrotic changes in cultured renal proximal tubular cells, supporting a profibrotic role of autophagy. Notably, pharmacological and genetic inhibition of HIF-1 led to the suppression of autophagy and renal fibrosis in these models. Mechanistically, knock down of BCL2 and adenovirus E1B 19-kDa-interacting protein 3 (BNIP3), a downstream target gene of HIF, decreased autophagy and fibrotic changes during hypoxia in BUMPT cells. Together, these results suggest that HIF-1 may activate autophagy via BNIP3 in renal tubular cells to facilitate the development of renal interstitial fibrosis.NEW & NOTEWORTHY Autophagy has been reported to participate in renal fibrosis, but its role and underlying activation mechanism is unclear. In this study, we report the role of HIF-1 in autophagy activation in models of renal fibrosis and further investigate the underlying mechanism.

MiR-199a-5p aggravates against renal ischemia-reperfusion and transplant injury by targeting AKAP1 to disrupt mitochondrial dynamics.

Renal ischemia-reperfusion injury (IRI) is a major cause of delayed graft function (DGF) after transplantation. Currently, a targeted therapy for this important clinical disorder is still lacking. MicroRNA (miRNA) has important roles in the pathogenesis of IRI and may therapeutic approaches to mitigate renal IRI. METHODS: Small RNA sequencing was performed to profile microRNA expression in mouse kidneys after transplantation. Lentivirus incorporating a miR-199a-5p modulator was injected into mouse kidney in situ before unilateral IRI and syngenetic transplantation, to determine the effect of miR-199a-5p in vivo. miR-199a-5p mimic or inhibitor was transfected cultured tubular cells before renal tubular ATP depletion recovery treatment to the examine the role of miR-199a-5p in vitro. RESULTS: Sequencing showed upregulation of miR-199a-5p in post-transplantation mouse kidney following renal IRI was localized to renal tubular epithelial cells. Lentivirus incorporating a miR-199a-5p mimic aggravated renal IRI and opposing effects were obtained with a miR-199a-5p inhibitor. Treatment with the miR-199a-5p inhibitor ameliorated graft function loss, tubular injury and immune response after cold storage transplantation. In vitro experiments demonstrated aggravation of cell death caused by ATP depletion and repletion when the miR-199a-5p mimic was present while the miR-199a-5p inhibitor reduced cell death. miR-199a-5p was shown to target a-kinase anchoring protein 1(AKAP1) by double luciferase assay and miR-199a-5p activation reduced dynamin related protein 1 (Drp1)-s637 phosphorylation and mitochondrial length. Overexpression of AKAP1 preserved Drp1-s637 phosphorylation and reduced mitochondrial fission. CONCLUSION: MiR-199a-5p activation reduced AKAP1 expression, promoted Drp1-s637 dephosphorylation, aggravated the disruption of mitochondrial dynamics and contributed to ischemic kidney injury.

Enhanced Frequency Conversion in Parity-Time Symmetry Line.

Non-Hermitian degeneracies reveal intriguing and nontrivial behaviors in open physical systems. Examples like parity-time (PT) symmetry breaking, topological encircling chirality, and enhanced sensing near an exceptional point (EP) are often associated with the abrupt nature of the phase transition around these degeneracies. Here we experimentally observe a cavity-enhanced second-harmonic frequency (SHG) conversion on a PT symmetry line, i.e., a set consisting of open-ended isofrequency or isoloss lines, both terminated at EPs on the Riemann surface in parameter space. The enhancement factor can reach as high as 300, depending on the crossing point whether in the symmetry or the broken phase of the PT line. Moreover, such enhancement of SHG enables sensitive distance sensing with a nanometer resolution. Our works may pave the way for practical applications in sensing, frequency conversion, and coherent wave control.

Inhibition of Drp1- Fis1 interaction alleviates aberrant mitochondrial fragmentation and acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is a common clinical disorder with complex etiology and poor prognosis, and currently lacks specific and effective treatment options. Mitochondrial dynamics dysfunction is a prominent feature in AKI, and modulation of mitochondrial morphology may serve as a potential therapeutic approach for AKI. METHODS: We induced ischemia-reperfusion injury (IRI) in mice (bilateral) and Bama pigs (unilateral) by occluding the renal arteries. ATP depletion and recovery (ATP-DR) was performed on proximal renal tubular cells to simulate in vitro IRI. Renal function was evaluated using creatinine and urea nitrogen levels, while renal structural damage was assessed through histopathological staining. The role of Drp1 was investigated using immunoblotting, immunohistochemistry, immunofluorescence, and immunoprecipitation techniques. Mitochondrial morphology was evaluated using confocal microscopy. RESULTS: Renal IRI induced significant mitochondrial fragmentation, accompanied by Dynamin-related protein 1 (Drp1) translocation to the mitochondria and Drp1 phosphorylation at Ser616 in the early stages (30 min after reperfusion), when there was no apparent structural damage to the kidney. The use of the Drp1 inhibitor P110 significantly improved kidney function and structural damage. P110 reduced Drp1 mitochondrial translocation, disrupted the interaction between Drp1 and Fis1, without affecting the binding of Drp1 to other mitochondrial receptors such as MFF and Mid51. High-dose administration had no apparent toxic side effects. Furthermore, ATP-DR induced mitochondrial fission in renal tubular cells, accompanied by a decrease in mitochondrial membrane potential and an increase in the translocation of the pro-apoptotic protein Bax. This process facilitated the release of dsDNA, triggering the activation of the cGAS-STING pathway and promoting inflammation. P110 attenuated mitochondrial fission, suppressed Bax mitochondrial translocation, prevented dsDNA release, and reduced the activation of the cGAS-STING pathway. Furthermore, these protective effects of P110 were also observed renal IRI model in the Bama pig and folic acid-induced nephropathy in mice. CONCLUSIONS: Dysfunction of mitochondrial dynamics mediated by Drp1 contributes to renal IRI. The specific inhibitor of Drp1, P110, demonstrated protective effects in both in vivo and in vitro models of AKI.

miR-147 Represses NDUFA4, Inducing Mitochondrial Dysfunction and Tubular Damage in Cold Storage Kidney Transplantation.

SIGNIFICANCE STATEMENT: Cold storage-associated transplantation (CST) injury occurs in renal transplant from deceased donors, the main organ source. The pathogenesis of CST injury remains poorly understood, and effective therapies are not available. This study has demonstrated an important role of microRNAs in CST injury and revealed the changes in microRNA expression profiles. Specifically, microRNA-147 (miR-147) is consistently elevated during CST injury in mice and in dysfunctional renal grafts in humans. Mechanistically, NDUFA4 (a key component of mitochondrial respiration complex) is identified as a direct target of miR-147. By repressing NDUFA4, miR-147 induces mitochondrial damage and renal tubular cell death. Blockade of miR-147 and overexpression of NDUFA4 reduce CST injury and improve graft function, unveiling miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation. BACKGROUND: Kidney injury due to cold storage-associated transplantation (CST) is a major factor determining the outcome of renal transplant, for which the role and regulation of microRNAs remain largely unclear. METHODS: The kidneys of proximal tubule Dicer (an enzyme for microRNA biogenesis) knockout mice and their wild-type littermates were subjected to CST to determine the function of microRNAs. Small RNA sequencing then profiled microRNA expression in mouse kidneys after CST. Anti-microRNA-147 (miR-147) and miR-147 mimic were used to examine the role of miR-147 in CST injury in mouse and renal tubular cell models. RESULTS: Knockout of Dicer from proximal tubules attenuated CST kidney injury in mice. RNA sequencing identified multiple microRNAs with differential expression in CST kidneys, among which miR-147 was induced consistently in mouse kidney transplants and in dysfunctional human kidney grafts. Anti-miR-147 protected against CST injury in mice and ameliorated mitochondrial dysfunction after ATP depletion injury in renal tubular cells in intro . Mechanistically, miR-147 was shown to target NDUFA4, a key component of the mitochondrial respiration complex. Silencing NDUFA4 aggravated renal tubular cell death, whereas overexpression of NDUFA4 prevented miR-147-induced cell death and mitochondrial dysfunction. Moreover, overexpression of NDUFA4 alleviated CST injury in mice. CONCLUSIONS: microRNAs, as a class of molecules, are pathogenic in CST injury and graft dysfunction. Specifically, miR-147 induced during CST represses NDUFA4, leading to mitochondrial damage and renal tubular cell death. These results unveil miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation.

MiR-20a-5p alleviates kidney ischemia/reperfusion injury by targeting ACSL4-dependent ferroptosis.

Ischemia/reperfusion injury (IRI) is prone to occur after kidney transplantation, leading to delayed graft function (DGF). MicroRNAs play a crucial role in the pathogenesis of ischemia/reperfusion-induced acute kidney injury, and miR-20a-5p was found to be the most significantly upregulated gene in a DGF patient cohort. However, the roles of microRNAs in transplanted kidneys remain largely unknown. In this study, we found that miR-20a-5p was upregulated in the kidneys of acute kidney injury mice and in patients with DGF. We identified early growth response-1 as a critical upstream target and verified the binding of early growth response-1 to a predicted sequence in the promoter region of the miR-20a-5p gene. Functionally, the miR-20a-5p mimic attenuated IRI and postischemic renal fibrosis, whereas the miR-20a-5p inhibitor delivery aggravated IRI and fibrosis. Importantly, delivery of the miR-20a-5p mimic or inhibitor in the donor kidneys attenuated or aggravated renal loss and structural damage in cold storage transplantation injury. Furthermore, our study identified miR-20a-5p as a negative regulator of acyl-CoA synthetase long-chain family member 4 (ACSL4) by targeting the 3' untranslated region of ACSL4 mRNA, thereby inhibiting ACSL4-dependent ferroptosis. Our results suggest a potential therapeutic application of miR-20a-5p in kidney transplantation through the inhibition of ACSL4-dependent ferroptosis.

Controllable EIT-like mode splitting in a chiral microcavity.

Two coupled resonance modes can lead to exotic transmission spectra due to internal interference processes. Examples include electromagnetically induced transparency (EIT) in atoms and mode splitting in optics. The ability to control individual modes plays a crucial role in controlling such transmission spectra for practical applications. Here we experimentally demonstrate a controllable EIT-like mode splitting in a single microcavity using a double-port excitation. The mode splitting caused by internal coupling between two counter-propagating resonances can be effectively controlled by varying the power of the two inputs, as well as their relative phase. Moreover, the presence of asymmetric scattering in the microcavity leads to chiral behaviors in the mode splitting in the two propagating directions, manifesting itself in terms of a Fano-like resonance mode. These results may offer a compact platform for a tunable device in all-optical information processing.

Endoplasmic reticulum stress contributes to cisplatin-induced chronic kidney disease via the PERK-PKCδ pathway.

BACKGROUND: Cisplatin is an effective chemotherapeutic drug, but it may induce both acute and chronic kidney problems. The pathogenesis of chronic kidney disease (CKD) associated with cisplatin chemotherapy remains largely unclear. METHODS: Mice and renal tubular cells were subjected to repeated low-dose cisplatin (RLDC) treatment to induce CKD and related pathological changes. The roles of endoplasmic reticulum (ER) stress, PERK, and protein kinase C-δ (PKCδ) were determined using pharmacological inhibitors and genetic manipulation. RESULTS: ER stress was induced by RLDC in kidney tubular cells in both in vivo and in vitro models. ER stress inhibitors given immediately after RLDC attenuated kidney dysfunction, tubular atrophy, kidney fibrosis, and inflammation in mice. In cultured renal proximal tubular cells, inhibitors of ER stress or its signaling kinase PERK also suppressed RLDC-induced fibrotic changes and the expression of inflammatory cytokines. Interestingly, RLDC-induced PKCδ activation, which was blocked by ER stress or PERK inhibitors, suggesting PKCδ may act downstream of PERK. Indeed, suppression of PKCδ with a kinase-dead PKCδ (PKCδ-KD) or Pkcδ-shRNA attenuated RLDC-induced fibrotic and inflammatory changes. Moreover, the expression of active PKCδ-catalytic fragment (PKCδ-CF) diminished the beneficial effects of PERK inhibitor in RLDC-treated cells. Co-immunoprecipitation assay further suggested PERK binding to PKCδ. CONCLUSION: These results indicate that ER stress contributes to chronic kidney pathologies following cisplatin chemotherapy via the PERK-PKCδ pathway.

Inhibition of HDAC3 protects against kidney cold storage/transplantation injury and allograft dysfunction.

Cold storage/rewarming is an inevitable process for kidney transplantation from deceased donors, which correlates closely with renal ischemia-reperfusion injury (IRI) and the occurrence of delayed graft function. Histone deacetylases (HDAC) are important epigenetic regulators, but their involvement in cold storage/rewarming injury in kidney transplantation is unclear. In the present study, we showed a dynamic change of HDAC3 in a mouse model of kidney cold storage followed by transplantation. We then demonstrated that the selective HDAC3 inhibitor RGFP966 could reduce acute tubular injury and cell death after prolonged cold storage with transplantation. RGFP966 also improved renal function, kidney repair and tubular integrity when the transplanted kidney became the sole life-supporting graft in the recipient mouse. In vitro, cold storage of proximal tubular cells followed by rewarming induced remarkable cell death, which was suppressed by RGFP966 or knockdown of HDAC3 with shRNA. Inhibition of HDAC3 decreased the mitochondrial pathway of apoptosis and preserved mitochondrial membrane potential. Collectively, HDAC3 plays a pathogenic role in cold storage/rewarming injury in kidney transplantation, and its inhibition may be a therapeutic option.

Vitamin D/vitamin D receptor/Atg16L1 axis maintains podocyte autophagy and survival in diabetic kidney disease.

OBJECTIVE: To investigate the effect of vitamin D/vitamin D receptor (VDR)/Atg16L1 signaling on podocyte autophagy and survival in diabetic nephropathy. METHODS: Diabetic rat models were induced by intraperitoneal injection of streptozotocin (STZ) (60 mg/kg) and treated with and without gavage of 0.1 µg/kg/d active vitamin D3 (aVitD3; 1,25- OH vitamin D3) and kidney tissues assessed by histopathology and immunohistochemistry. The murine podocyte cell line MPC-5 was cultured under hyperglycemic conditions in the absence or presence of 100 nmol/L calcitriol to investigate podocyte injury and autophagy. Cell survival rates were analyzed using Cell Counting Kit-8 (CCK-8) assays and the numbers of autophagosomes were determined after transduction with the mRFP-GFP-LC3 autophagy reporter construct. The expression of autophagy-related proteins (LC3-II, beclin-1, Atg16L1) and podocyte-related proteins (nephrin, podocin, synaptopodin, and desmin) was determined by Western blotting. RESULTS: VDR expression and autophagy were decreased in diabetic nephropathy. Calcitriol treatment repressed renal injury in rat diabetic kidneys and reduced high glucose-induced damage to cultured podocytes. Mechanistically, Atg16L1 was identified as a functional target of VDR, and siRNA-mediated knockdown of VDR and Atg16L1 blocked the protective effects of aVitD3 against podocyte damage. CONCLUSION: Autophagy protects podocytes from damage in DN and is modulated by VitD3/VDR signaling and downstream regulation of Atg16L1 expression.

Primary hyperoxaluria diagnosed after kidney transplantation: a case report and literature review.

BACKGROUND: Primary hyperoxaluria (PH) is a rare inherited autosomal recessive disease caused by disturbed glyoxylate metabolism. The disease is characterized by calcium oxalate crystal deposition in various organs, especially in the kidney. Due to the lack of current understanding of PH, nearly all patients are only initially diagnosed with PH when recurrent lithiasis and progressive end-stage renal disease occur. Many cases are not diagnosed in patients until renal allograft insufficiency occurs after renal transplantation. This case report and literature review aim to emphasize the need for careful pre-transplant PH screening of patients with bilateral nephrocalcinosis or nephrolithiasis. CASE PRESENTATION: Renal allograft insufficiency was diagnosed as PH after kidney transplantation. Here, we detail the complete clinical course, including computed tomography images of the original kidney and renal graft, histopathological images of a biopsy of the transplanted kidney, the results of laboratory and molecular genetic tests, and the treatment. In addition, we reviewed the literature from 2000 to 2021 and analyzed 19 reported cases of PH diagnosed after kidney transplantation, and provide a summary of the characteristics, complications, treatment, and prognosis of these cases. CONCLUSIONS: By reviewing and analyzing these cases, we concluded that patients with a history of nephrocalcinosis or nephrolithiasis in both kidneys need preoperative screening for PH and appropriate treatment before kidney transplantation. Delayed graft function caused by PH is easily misdiagnosed as acute rejection, and needle biopsy should be performed at an early stage.

Protein Kinase C-δ Mediates Kidney Tubular Injury in Cold Storage-Associated Kidney Transplantation.

BACKGROUND: Kidney injury associated with cold storage is a determinant of delayed graft function and the long-term outcome of transplanted kidneys, but the underlying mechanism remains elusive. We previously reported a role of protein kinase C-δ (PKCδ) in renal tubular injury during cisplatin nephrotoxicity and albumin-associated kidney injury, but whether PKCδ is involved in ischemic or transplantation-associated kidney injury is unknown. METHODS: To investigate PKCδ's potential role in injury during cold storage-associated transplantation, we incubated rat kidney proximal tubule cells in University of Wisconsin (UW) solution at 4°C for cold storage, returning them to normal culture medium at 37°C for rewarming. We also stored kidneys from donor mice in cold UW solution for various durations, followed by transplantation into syngeneic recipient mice. RESULTS: We observed PKCδ activation in both in vitro and in vivo models of cold-storage rewarming or transplantation. In the mouse model, PKCδ was activated and accumulated in mitochondria, where it mediated phosphorylation of a mitochondrial fission protein, dynamin-related protein 1 (Drp1), at serine 616. Drp1 activation resulted in mitochondrial fission or fragmentation, accompanied by mitochondrial damage and tubular cell death. Deficiency of PKCδ in donor kidney ameliorated Drp1 phosphorylation, mitochondrial damage, tubular cell death, and kidney injury during cold storage-associated transplantation. PKCδ deficiency also improved the repair and function of the renal graft as a life-supporting kidney. An inhibitor of PKCδ, δV1-1, protected kidneys against cold storage-associated transplantation injury. CONCLUSIONS: These results indicate that PKCδ is a key mediator of mitochondrial damage and renal tubular injury in cold storage-associated transplantation and may be an effective therapeutic target for improving renal transplant outcomes.

Canagliflozin reduces cisplatin uptake and activates Akt to protect against cisplatin-induced nephrotoxicity.

Cisplatin is a widely used chemotherapy drug with notorious nephrotoxicity. Na+-glucose cotransporter 2 inhibitors are a class of novel antidiabetic agents that may have other effects in the kidneys besides blood glucose control. In the present study, we demonstrated that canagliflozin significantly attenuates cisplatin-induced nephropathy in C57BL/6 mice and suppresses cisplatin induced renal proximal tubular cell apoptosis in vitro. The protective effect of canagliflozin was associated with inhibition of p53, p38 and JNK activation. Mechanistically, canagliflozin partially reduced cisplatin uptake by kidney tissues in mice and renal tubular cells in culture. In addition, canagliflozin enhanced the activation of Akt and inhibited the mitochondrial pathway of apoptosis during cisplatin treatment. The protective effect of canagliflozin was diminished by the phosphatidylinositol 3-kinase/Akt inhibitor LY294002. Notably, canagliflozin did not affect the chemotherapeutic efficacy of cisplatin in A549 and HCT116 cancer cell lines. These results suggest a new application of canagliflozin for renoprotection in cisplatin chemotherapy. Canagliflozin may protect kidneys by reducing cisplatin uptake and activating cell survival pathways.

miR-214 represses mitofusin-2 to promote renal tubular apoptosis in ischemic acute kidney injury.

Disruption of mitochondrial dynamics is an important pathogenic event in both acute and chronic kidney diseases, but the underlying mechanism remains poorly understood. Here, we report the regulation of mitofusin-2 (Mfn2; a key mitochondrial fusion protein) by microRNA-214 (miR-214) in renal ischemia-reperfusion that contributes to mitochondrial fragmentation, renal tubular cell death, and ischemic acute kidney injury (AKI). miR-214 was induced, whereas Mfn2 expression was decreased, in mouse ischemic AKI and cultured rat kidney proximal tubular cells (RPTCs) following ATP depletion treatment. Overexpression of miR-214 decreased Mfn2. Conversely, inhibition of miR-214 with anti-miR-214 prevented Mfn2 downregulation in RPTCs following ATP depletion. Anti-miR-214 further ameliorated mitochondrial fragmentation and apoptosis, whereas overexpression of miR-214 increased apoptosis, in ATP-depleted RPTCs. To test regulation in vivo, we established a mouse model with miR-214 specifically deleted from kidney proximal tubular cells (PT-miR-214-/-). Compared with wild-type mice, PT-miR-214-/- mice had less severe tissue damage, fewer apoptotic cells, and better renal function after ischemic AKI. miR-214 induction in ischemic AKI was suppressed in PT-miR-214-/- mice, accompanied by partial preservation of Mfn2 in kidneys. These results unveil the miR-214/Mfn2 axis that contributes to the disruption of mitochondrial dynamics and tubular cell death in ischemic AKI, offering new therapeutic targets.

Aberrant DNA methylation of mTOR pathway genes promotes inflammatory activation of immune cells in diabetic kidney disease.

DNA methylation has been implicated in the pathogenesis of diabetic kidney disease (DKD), but the underlying mechanisms remain unclear. In this study, we tested the hypothesis that aberrant DNA methylation in peripheral immune cells contributes to DKD progression. We showed that levels of DNA methyltransferase 1 (DNMT1), a key enzyme for DNA methylation, were increased along with inflammatory activity of peripheral blood mononuclear cells in DKD patients. Inhibition of DNMT1 with 5-aza-2'-deoxycytidine (5-Aza) markedly increased the proportion of CD4+CD25+ regulatory T cells in peripheral blood mononuclear cells in culture and in diabetic animals. Adoptive transfer of immune cells from 5-Aza-treated animals showed beneficial effects on the host immune system, resulting in a significant improvement of DKD. Using genome-wide DNA methylation assays, we identified the differentially methylated cytosines in the promoter regions of mammalian target of rapamycin (mTOR) regulators in peripheral blood mononuclear cells of diabetic patients. Further, mRNA arrays confirmed the consistent induction of genes expressed in the mTOR pathway. Importantly, down-regulation of DNMT1 expression via RNA interference resulted in prominent cytosine demethylation of mTOR negative regulators and subsequent decrease of mTOR activity. Lastly, modulation of mTOR resulted in changes in the effect of 5-aza on diabetic immune cells. Thus, up-regulation of DNMT1 in diabetic immune cells induces aberrant cytosine methylation of the upstream regulators of mTOR, leading to pathogenic activation of the mTOR pathway and consequent inflammation in diabetic kidneys. Hence, this study highlights therapeutic potential of targeting epigenetic events in immune system for treating DKD.

Regulation of IgA Class Switch Recombination in Immunoglobulin A Nephropathy: Retinoic Acid Signaling and BATF.

BACKGROUND: Immunoglobulin (Ig) A nephropathy (IgAN) is the xFB01;nding of immune deposits predominantly containing polymeric IgA in the glomerular mesangium on renal biopsy. Increasing evidence suggested that retinoic acid (RA) signaling selectively induces IgA isotype switching and basic leucine zipper transcription factor, ATF-like (BATF) controls the global regulators of class switch recombination (CSR) in lymphocytes. Great effort has been paid to identify whether impaired immune regulation along the 'mucosa-bone marrow (BM) axis' play an important role in the pathogenesis of IgAN. METHODS: The aim of the study was to investigate the expression of all-trans-RA (ATRA) and BATF, and to identify their impact on IgA CSR in IgAN patients and rat animal models. Blood samples and tonsillar tissue specimens were obtained from 22 patients with IgAN and 24 patients with chronic tonsillitis as control. RESULTS: Immunohistochemical, RT-PCR and western blotting examination revealed that RA signaling and BATF productions are activated in IgAN patients compared with controls. Lipopolysaccharide and α-hemolytic streptococcus stimulation upregulated RA receptor (RAR) and BATF expression, promote IgA CSR and ATRA productions in tonsil mononuclear cells. RAR alpha (RARα) or BATF siRNA decreases IgA expression. We also built IgAN rat models and found that RARα, BATF and activation-induced cytidine deaminase were upregulated in the peripheral blood, spleen and BM. With ATRA (500 µg/kg body weight) treatment for 8 weeks, IgA deposition on glomeruli and mesangial cells proliferation increased. It also revealed that ATRA activated BATF and IgA CSR in vivo. CONCLUSION: These data point toward the role of RA signaling together with BATF in IgA CSR of IgAN, and the data also support the notion that mucosal immunization with neoantigen results in impaired mucosal and systemic IgA responses.

Lipopolysaccharide Induces Chronic Kidney Injury and Fibrosis through Activation of mTOR Signaling in Macrophages.

BACKGROUND: Septic kidney injury is one of the most common complications in critically ill patients with a high risk of developing chronic kidney disease (CKD). Emerging data indicate that mammalian target of rapamyci (mTOR) signaling plays a major role in septic inflammation by regulating the immune response of macrophage. This study was designed to evaluate the role of mTOR signaling in kidney macrophages during endotoxemia-induced chronic kidney injury and subsequent fibrogenesis. METHODS: Male C57BL/6 mice were used for all animal studies (n=9 for each group). Lipopolysaccharide (LPS) was injected intraperitoneally (1 mg/kg) every 2 days to induce persistent endotoxemia. Rapamycin (1 mg/kg·day) was administered to a subgroup of mice 1 day prior to LPS treatment and continued to termination of the experiment. In ex-vivo experiment, RAW264.7 cells were cultured and treated with LPS (2 µg/ml) for 48 h while a subgroup of cells were incubated in the presence of rapamycin (50 nmol) for 2 h. RESULTS: Continuous administration of LPS resulted in progressive macrophage infiltration, tubular injury and collagen deposition in mice kidneys. Rapamycin markedly ameliorated LPS-induced kidney pathological changes. Expression of pS6K was rarely observed in normal kidney macrophages, but significantly increased with time by LPS treatment. In ex-vivo study, LPS induced prominent production of IL-1ß and MCP-1 in cultured RAW264.7 cells, which was significantly suppressed by rapamycin. CONCLUSION: Taken together, our findings show that endotoxemia results in activation of mTOR signaling in macrophages, leading to progressive kidney inflammatory injuries and subsequent fibrosis. Our study may reveal a mechanism involved in the development of sepsis-associated CKD and kidney fibrosis.

Protective effects of curcumin on acute gentamicin-induced nephrotoxicity in rats.

BACKGROUND: Gentamicin-induced nephrotoxicity is one of the most common causes of acute kidney injury (AKI). The phenotypic alterations that contribute to acute kidney injury include inflammatory response and oxidative stress. Curcumin has a wide range biological functions, especially as an antioxidant. This study was designed to evaluate the renoprotective effects of curcumin treatment in gentamicin-induced AKI. METHODS: Gentamicin-induced AKI was established in female Sprague-Dawley rats. Rats were treated with curcumin (100 mg/kg body mass) by intragastric administration, once daily, followed with an intraperitoneal injection of gentamicin sulfate solution at a dose of 80 mg/kg body mass for 8 consecutive days. At days 3 and 8, the rats were sacrificed, and the kidneys and blood samples were collected for further analysis. RESULTS: The animals treated with gentamicin showed marked deterioration of renal function, together with higher levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) in the plasma as compared with the controls. Animals that underwent intermittent treatment with curcumin exhibited significant improvements in renal functional parameters. We also observed that treatment with curcumin significantly attenuated renal tubular damage, apoptosis, and oxidative stress. Curcumin treatment exerted anti-apoptosis and anti-oxidative effects by up-regulating Nrf2/HO-1 and Sirt1 expression. CONCLUSIONS: Our data clearly demonstrate that curcumin protects kidney from gentamicin-induced AKI via the amelioration of oxidative stress and apoptosis of renal tubular cells, thus providing hope for the amelioration of gentamicin-induced nephrotoxicity.

Mangiferin attenuate sepsis-induced acute kidney injury via antioxidant and anti-inflammatory effects.

BACKGROUND: Acute kidney injury (AKI) is a frequent and serious complication of sepsis. A growing body of evidence now suggests that inflammatory reactions and tubular dysfunction induced by oxidative stress involved in the mechanisms of the disease. This study aimed to determine the role of anti-inflammatory and anti-oxidant activities of mangiferin (MA) in sepsis-induced AKI. METHODS: We investigated the effects of MA on apoptosis of rat kidney proximal tubular cell (RPTC), together with renal function and morphological alterations of mice undergoing cecal-ligation and puncture (CLP). The levels of oxidative stress in kidney tissues were also determined. Moreover, we mainly focus on the effects of MA in regulating the production of NLRP3 and Nrf2 in the present study. RESULTS: The exposure to LPS (5 µg/ml) yielded a significant increase of apoptosis in RPTC cells, which was largely inhibited by MA pretreatment. MA attenuates renal dysfunction and ameliorates the morphological changes in the septic mice induced by CLP. MA inhibits oxidative stress, decreases serum levels of IL-1ß and IL-18, and prevents tubular epithelial cells apoptosis in kidneys of CLP mice model. Data in this study also suggest that MA promotes Nrf2 expression and suppresses renal NLRP3 inflammasome activation. CONCLUSION: In summary, MA protects against sepsis-induced AKI through NLRP3 inflammasome inhibition and Nrf2 up-regulation. Thus, the mangiferin could thus be a promising candidate for development of a multi-potent drug.

Identification of Differentially Expressed Genes in Cold Storage-associated Kidney Transplantation.

BACKGROUND: Although it is acknowledged that ischemia-reperfusion injury is the primary pathology of cold storage-associated kidney transplantation, its underlying mechanism is not well elucidated. METHODS: To extend the understanding of molecular events and mine hub genes posttransplantation, we performed bulk RNA sequencing at different time points (24 h, day 7, and day 14) on a murine kidney transplantation model with prolonged cold storage (10 h). RESULTS: In the present study, we showed that genes related to the regulation of apoptotic process, DNA damage response, cell cycle/proliferation, and inflammatory response were steadily elevated at 24 h and day 7. The upregulated gene profiling delicately transformed to extracellular matrix organization and fibrosis at day 14. It is prominent that metabolism-associated genes persistently took the first place among downregulated genes. The gene ontology terms of particular note to enrich are fatty acid oxidation and mitochondria energy metabolism. Correspondingly, the key enzymes of the above processes were the products of hub genes as recognized. Moreover, we highlighted the proximal tubular cell-specific increased genes at 24 h by combining the data with public RNA-Seq performed on proximal tubules. We also focused on ferroptosis-related genes and fatty acid oxidation genes to show profound gene dysregulation in kidney transplantation. CONCLUSIONS: The comprehensive characterization of transcriptomic analysis may help provide diagnostic biomarkers and therapeutic targets in kidney transplantation.