Risk Factors for Locoregional Recurrence and Distant Metastasis in 143 Patients with Adenoid Cystic Carcinoma of the External Auditory Canal

AIMS

Adenoid cystic carcinoma (ACC) grows slowly and is characterised by potential recurrence and metastasis to distant organs. This study aimed to evaluate the risk factors for locoregional recurrence (LRR) and distant metastasis in patients with ACC of the external auditory canal (EAC).

MATERIALS AND METHODS

Demographic, pathological, therapeutic and survival data of 143 patients with EAC ACC were reviewed in this study. Univariate and multivariate Cox proportional hazard regression analyses were carried out to determine the risk factors for LRR and distant metastasis. Factors associated with overall survival after LRR and distant metastasis were also analysed.

RESULTS

During a median follow-up of 49 months, 31 of 143 patients were observed with LRR and 34 developed distant metastasis. Bone invasion and histological subtype were independent risk factors for locoregional recurrence-free survival. T stage and LRR were independent risk factors for distant metastasis-free survival. Salvage surgery and adjuvant radiotherapy or chemoradiotherapy for LRR resulted in better survival, whereas extrapulmonary metastasis and LRR were associated with a higher risk of poor survival after distant metastasis.

CONCLUSION

Patients with distant metastases, especially those with LRR, are at significant risk of poor prognosis. Our findings emphasise the importance of long-term regular follow-up and recommend surgical intervention with radiotherapy for recurrent EAC ACC.

Palmitoyltransferase DHHC9 and acyl protein thioesterase APT1 modulate renal fibrosis through regulating β-catenin palmitoylation

palmitoylation, a reversible post-translational modification, is initiated by the DHHC family of palmitoyltransferases and reversed by several acyl protein thioesterases. However, the role and mechanisms for protein palmitoylation in renal fibrosis have not been elucidated. Here we show protein palmitoylation and DHHC9 were downregulated in the fibrotic kidneys of mouse models and chronic kidney disease (CKD) patients. Ablating DHHC9 in tubular cells aggravated, while inducing DHHC9 overexpression with adeno-DHHC9 transfection or iproniazid treatment protected against kidney fibrosis in male mouse models. Mechanistically, DHHC9 palmitoylated β-catenin, thereby promoted its ubiquitination and degradation. Additionally, acyl protein thioesterase 1 (APT1) was induced in the fibrotic kidneys, which depalmitoylated β-catenin, increased its abundance and nuclear translocation. Ablating tubular APT1 or inhibiting APT1 with ML348 markedly protected against unilateral ureter obstruction (UUO) or ischemia/reperfusion injury (IRI)-induced kidney fibrosis in male mice. This study reveals the regulatory mechanism of protein palmitoylation in kidney fibrosis.

Crosstalk between Interleukin-1 Receptor-Like 1 and Transforming Growth Factor-β Receptor Signaling Promotes Renal Fibrosis

IL-33, a member of the IL-1 family, acts as an alarmin in immune response. Epithelial-mesenchymal transition and transforming growth factor-β (TGF-β)–induced fibroblast activation are key events in the development of renal interstitial fibrosis. The current study found increased expression of IL-33 and interleukin-1 receptor-like 1 (IL1RL1, alias ST2), the receptor for IL-33, in human fibrotic renal tissues. In addition, IL-33– or ST2-deficient mice showed significantly reduced levels of fibronectin, α-smooth muscle actin, and vimentin, and increased E-cadherin levels. In HK-2 cells, IL-33 promotes the phosphorylation of the TGF-β receptor (TGF-βR), Smad2, and Smad3, and the production of extracellular matrix (ECM), with reduced expression of E-cadherin. Blocking TGF-βR signaling or suppressing ST2 expression impeded Smad2 and Smad3 phosphorylation, thereby reducing ECM production, suggesting that IL-33–induced ECM synthesis requires cooperation between the two pathways. Mechanistically, IL-33 treatment induced a proximate interaction between ST2 and TGF-βRs, activating downstream Smad2 and Smad3 for ECM production in renal epithelial cells. Collectively, this study identified a novel and essential role for IL-33 in promoting TGF-β signaling and ECM production in the development of renal fibrosis. Therefore, targeting IL-33/ST2 signaling may be an effective therapeutic strategy for renal fibrosis.

An international Delphi consensus statement on metabolic dysfunction-associated fatty liver disease and risk of chronic kidney disease

BACKGROUND

With the rising global prevalence of fatty liver disease related to metabolic dysfunction, the association of this common liver condition with chronic kidney disease (CKD) has become increasingly evident. In 2020, the more inclusive term metabolic dysfunction-associated fatty liver disease (MAFLD) was proposed to replace the term non-alcoholic fatty liver disease (NAFLD). The observed association between MAFLD and CKD and our understanding that CKD can be a consequence of underlying metabolic dysfunction support the notion that individuals with MAFLD are at higher risk of having and developing CKD compared with those without MAFLD. However, to date, there is no appropriate guidance on CKD in individuals with MAFLD. Furthermore, there has been little attention paid to the link between MAFLD and CKD in the Nephrology community.

METHODS AND RESULTS

Using a Delphi-based approach, a multidisciplinary panel of 50 international experts from 26 countries reached a consensus on some of the open research questions regarding the link between MAFLD and CKD.

CONCLUSIONS

This Delphi-based consensus statement provided guidance on the epidemiology, mechanisms, management and treatment of MAFLD and CKD, as well as the relationship between the severity of MAFLD and risk of CKD, which establish a framework for the early prevention and management of these two common and interconnected diseases.

[Correction model of the sampling time error on the blood trough concentration of tacrolimus in non-sustained-release dosage form for renal transplant recipients]

Objective: To establish correction model of the sampling time error on the blood trough concentration of tacrolimus in non-sustained-release dosage form for renal transplant recipient and improve the accuracy of drug dose assessment and clinical adjustment in renal transplant recipients. Methods: Visit records of 206 outpatients in the Department of Transplantation, Nanfang Hospital, Southern Medical University were retrospectively collected from October 15, 2022 to October 30, 2022. The distribution of sampling time of tacrolimus blood drug concentration was described and the time range of correction was determined. Twenty inpatients after renal transplantation in the Department of Transplantation, Nanfang Hospital, Southern Medical University from October 1, 2022 to November 30, 2022 were prospectively included, and their demography data, laboratory test results during follow-ups, and CYP3A5 genotype were collected. The patients took tacrolimus in non-sustained-release dosage form every 12 h starting from 19∶30 on the day of admission. Peripheral blood samples were collected from the patients on the second day of admission at 7∶30 and on the third day at 6∶00-10∶00 every 30 minutes to test the blood concentration of tacrolimus. Using the collection time as the independent variable and the blood tacrolimus concentration as the dependent variable, a simple linear regression was performed to fitting a linear model of tacrolimus blood concentration-sampling time. Multiple linear regression was performed to analyze the influencing factors of the tacrolimus metabolic rate within a specific period and generate the regression equation. Results: The 206 outpatients aged (46±13) years, including 131 males (63.6%). The time gap [M (Q₁, Q₃)] between the sampling time of the follow-up outpatients and standard C₁₂ was 24 (13.0, 46.5) min, and the maximum time gap was 135 min. The 20 enrolled inpatients aged (45±12) years, including 15 males (75.0%). There was no significant difference in the blood concentration of tacrolimus collected at 7∶30 on the second (7.87±2.21)ng/ml and third days (7.84±2.33)ng/ml after admission of the enrolled inpatients (P=0.917), and the blood tacrolimus concentration rhythm was stable in the trial. The plasma concentration of C_10.5-C_14.5 was linearly related to the time, with R² [M (Q₁, Q₃)] 0.88 (0.85, 0.92) and all P<0.05. The metabolic rate of tacrolimus during C_10.5-C_14.5=0.984+0.090×basic concentration of tacrolimus (ng/ml)-0.036×body mass index+0.489×CYP3A5 genotype-0.007×hemolobin(g/L)-0.035×alanine aminotransferase (U/L)+0.143×total cholesterol (mmol/L)+0.027×total bilirubin (μmol/L), with R²=0.85. Conclusion: This study propose a correction model for tacrolimus (non-sustained-release dosage form) trough concentration around C₁₂, which is helpful for clinicians to easily and accurately assess renal transplant recipients' tacrolimus exposure.

UXT attenuates the CGAS-STING1 signaling by targeting STING1 for autophagic degradation

STING1 (stimulator of interferon response cGAMP interactor 1), the pivotal adaptor protein of CGAS (cyclic GMP-AMP synthase)-STING1 signaling, is critical for type I IFN production of innate immunity. However, excessive or prolonged activation of STING1 is associated with autoinflammatory and autoimmune diseases. Thus, preventing STING1 from over-activation is important to maintain immune homeostasis. Here, we reported that UXT (ubiquitously expressed prefoldin like chaperone), a small chaperone-like protein, was essential to prevent the excessive activation of STING1-mediated type I IFN signaling through autophagic degradation of STING1 via SQSTM1 (sequestosome 1). Upon DNA mimics or cyclic GMP-AMP (cGAMP) stimulation, UXT specifically interacted with STING1 and promoted STING1 degradation through selective macroautophagy/autophagy. Moreover, UXT was required for more efficient autophagic degradation of STING1 by facilitating the interaction of SQSTM1 and STING1. The in vivo role of UXT in attenuating the CGAS-STING1 signaling was further confirmed in the mouse model of DNA-virus infection and the TMPD (2,6,10,14-tetramethylpentadecane)-induced murine lupus model. Intriguingly, the expression of UXT was consistently impaired and exhibited a remarkable inverse correlation with type I IFN signature in the leukocytes and PBMCs (peripheral blood mononuclear cells) of several large SLE (systemic lupus erythematosus) cohorts. Importantly, the replenishment of UXT effectively suppressed the production of IFNs and ISGs in the PBMCs of SLE patients. Taken together, our study reveals a novel regulatory role of UXT in autophagic degradation of STING1 to maintain immune homeostasis. UXT might be a potential therapeutic target for alleviating aberrant type I IFNs in autoimmune diseasesAbbreviations: 3-MA: 3-methyladenine; BMDMs: bone marrow-derived macrophages; cGAMP: cyclic GMP-AMP; CGAS: cyclic gmp-amp synthase; cKO: conditional knockout; CXCL10: C-X-C motif chemokine ligand 10; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HSV-1: herpes simplex virus type 1; HTDNA: herring testes DNA; IFIT1: interferon induced protein with tetratricopeptide repeats 1; IFNA4: interferon alpha 4; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISD: interferon stimulatory DNA; ISGs: IFN-stimulated genes; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEFs: mouse embryonic fibroblasts; RNA-seq: RNA sequencing; PBMCs: peripheral blood mononuclear cells; RSAD2: radical S-adenosyl methionine domain containing 2; SLE: systemic lupus erythematosus; SQSTM1: sequestosome 1; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; TMPD: 2,6,10,14-tetramethylpentadecane; UXT: ubiquitously expressed prefoldin like chaperone.

Differential Expression of Autophagy-Related Long Non-Coding RNA in Melanoma

To explore the role of autophagy-related differential long non-coding RNA (lncRNA) in the pathogenesis of melanoma, we established a prognostic prediction model for patients with melanoma based on the expression profiles of autophagy-related gene. Based on The Cancer Genome Atlas and GeneCard database, we used single-sample gene set enrichment analysis (ssGSEA), weighted gene co-expression network analysis (WGCNA), uniCOX in R software for COX proportional hazard regression analysis, and enrichment analysis to get an idea of biological processes with autophagy-related genes, which evaluates the relationship between autophagy-related genes and immune cell infiltration in patients with melanoma. The roles of identified lncRNA were evaluated by the risk score based on the results of single factor regression analysis for each lncRNA and on the prognosis for patients obtained from the database. Then, the whole sample was divided into high- and low-risk groups. Survival curve analysis showed that low-risk group had a better prognosis. Enrichment analysis revealed multiple key pathways enriched with lncRNA-associated genes. Analysis of immune cell infiltration revealed differences between high- and low-risk groups. Finally, 3 datasets verified the effect of our model on prognosis. There are important autophagy-related lncRNA in patients with melanoma. Top 6 lncRNA are significantly related to the overall survival rate of patients with melanoma and provide the basis for predicting the prognostic survival of patients.

Follistatin-like 1 (FSTL1) interacts with Wnt ligands and Frizzled receptors to enhance Wnt/β-catenin signaling in obstructed kidneys in vivo

Follistatin (FS)-like 1 (FSTL1) is a member of the FS-SPARC (secreted protein, acidic and rich in cysteine) family of secreted and extracellular matrix proteins. The functions of FSTL1 have been studied in heart and lung injury as well as in wound healing; however, the role of FSTL1 in the kidney is largely unknown. Here, we show using single-cell RNA-Seq that Fstl1 was enriched in stromal cells in obstructed mouse kidneys. In addition, immunofluorescence demonstrated that FSTL1 expression was induced in fibroblasts during kidney fibrogenesis in mice and human patients. We demonstrate that FSTL1 overexpression increased renal fibrosis and activated the Wnt/β-catenin signaling pathway, known to promote kidney fibrosis, but not the transforming growth factor β (TGF-β), Notch, Hedgehog, or Yes-associated protein (YAP) signaling pathways in obstructed mouse kidneys, whereas inhibition of FSTL1 lowered Wnt/β-catenin signaling. Importantly, we show that FSTL1 interacted with Wnt ligands and the Frizzled (FZD) receptors but not the coreceptor lipoprotein receptor–related protein 6 (LRP6). Specifically, we found FSTL1 interacted with Wnt3a through its extracellular calcium–binding (EC) domain and von Willebrand factor type C–like (VWC) domain, and with FZD4 through its EC domain. Furthermore, we show that FSTL1 increased the association of Wnt3a with FZD4 and promoted Wnt/β-catenin signaling and fibrogenesis. The EC domain interacting with both Wnt3a and FZD4 also enhanced Wnt3a signaling. Therefore, we conclude that FSTL1 is a novel extracellular enhancer of the Wnt/β-catenin pathway.

Resveratrol ameliorates high-phosphate-induced VSMCs to osteoblast-like cells transdifferentiation and arterial medial calcification in CKD through regulating Wnt/β-catenin signaling

Vascular smooth muscle cells (VSMCs) to osteoblast-like cells transdifferentiation induced by high-phosphate is a crucial step in the development of arterial medial calcification (AMC) in patients with chronic kidney disease (CKD), and previous studies implicate Wnt/β-catenin signaling in osteogenic transdifferentiation of VSMCs and AMC. Given that resveratrol's ability to modulate Wnt/β-catenin signaling in other types of cell, we tested the effect of resveratrol on high-phosphate-induced osteogenic transdifferentiation of VSMCs and AMC in CKD. Resveratrol ameliorated AMC in rats with chronic renal failure and calcium deposition in aortic rings and VSMCs cultured in a high-phosphate environment. Resveratrol also diminished high-phosphate-induced osteogenic transdifferentiation of VSMCs in cultured aortic rings and VSMCs. In vitro, resveratrol attenuated the activation of β-catenin induced by high-phosphate and inhibited the expression of Runx2, a downstream effector of Wnt/β-catenin signaling during osteogenic transdifferentiation of VSMCs. Intriguingly, resveratrol inhibited high-phosphate-induced phosphorylation of LRP6 (Ser1490), but didn't inhibit Wnt3a-induced phosphorylation of LRP6 (Ser1490) and Runx2 expression. The expression of several Wnts was induced by high-phosphate, but the expression of Wnt7a, not Wnt2b and Wnt10a could be suppressed by resveratrol. In addition, the expression of both porcupine and wntless, two obligatory proteins for Wnt secretion, was induced by high-phosphate in cultured aortic rings and VSMCs, which could be suppressed by resveratrol. In summary, these findings suggest that resveratrol possesses a vascular protective effect on retarding high-phosphate-induced osteogenic transdifferentiation of VSMCs and AMC in CKD by targeting Wnt/β-catenin signaling, which may, to a large extent, via impeding Wnt secretion.

Protein phosphatase 2Acα modulates fatty acid oxidation and glycolysis to determine tubular cell fate and kidney injury

Energy metabolism is crucial in maintaining cellular homeostasis and adapting to stimuli for tubular cells. However, the underlying mechanisms remain largely unknown. Here, we report that PP2Acα was upregulated in damaged tubular cells from patients and animal models with acute or chronic kidney injury. Using in vitro and in vivo model, we demonstrated that PP2Acα induction in damaged tubular cells suppresses fatty acid oxidation and promotes glycolysis, leading to cell death and fibrosis. Mechanistically, we revealed that PP2Acα dephosphorylates ACC through interaction with B56δ, leading to the regulation of fatty acid oxidation. Furthermore, PP2Acα also dephosphorylates p-Glut1 (Thr478) and suppresses Trim21-mediated Glut1 ubiquitination and degradation, leading to the promotion of glucose intake and glycolysis. Thus, this study adds new insight into the tubular cell metabolic alterations in kidney diseases. PP2Acα may be a promising therapeutic target for kidney injury.

Metabolic Regulation of Fibroblast Activation and Proliferation during Organ Fibrosis

Background

Activated fibroblasts are present in the injury response, tumorigenesis, fibrosis, and inflammation in a variety of tissues and myriad disease types.

Summary

During normal tissue repair, quiescent fibroblasts transform into a proliferative and contractile phenotype termed myofibroblasts and are then lost as repair resolves to form a scar. When excessive levels are reached, activated fibroblasts proliferate and produce large amounts of extracellular matrix, which accumulates in the interstitial space of different organs. This accumulation leads to fibrotic dysfunction and multiple-organ dysfunction syndrome. To date, there are limited effective treatments for these conditions. Cellular metabolism is the cornerstone of all biological activities. Emerging evidence shows that metabolic alterations in fibroblasts are important for the activation process and illness progression. These discoveries, along with current clinical advances showing decreased lung fibrosis after targeting specific metabolic pathways, thus offer new possibilities for therapeutic interventions. The purpose of this review was to summarize the most recent knowledge of the major metabolic changes that occur during fibroblast transition from quiescent to activated states and the evidence linking alterations in fibroblast metabolism to the pathobiology of several common fibrotic diseases and tumor-related diseases.

Key Messages

Metabolic disorders are associated with the progression of chronic kidney diseases. Interfering with fibroblast metabolism may be a promising therapeutic strategy for renal fibrosis and other fibrosis-related diseases.

Targeting Ferroptosis Attenuates Interstitial Inflammation and Kidney Fibrosis

BACKGROUND

Ferroptosis, an iron-dependent form of regulated necrosis mediated by lipid peroxidation, predominantly polyunsaturated fatty acids, is involved in postischemic and toxic kidney injury. However, the role and mechanisms for tubular epithelial cell (TEC) ferroptosis in kidney fibrosis remain largely unknown.

OBJECTIVES

The aim of the study was to decipher the role and mechanisms for TEC ferroptosis in kidney fibrosis.

METHODS

Mouse models with unilateral ureter obstruction (UUO) or ischemia/reperfusion injury (IRI) were generated.

RESULTS

We found that TEC ferroptosis exhibited as reduced glutathione peroxidase 4 (GPX4) expression and increased 4-hydroxynonenal abundance was appeared in kidneys from chronic kidney disease (CKD) patients and mouse models with UUO or IRI. Inhibition of ferroptosis could largely mitigate kidney injury, interstitial fibrosis, and inflammatory cell accumulation in mice after UUO or IRI. Additionally, treatment of TECs with (1S,3R)-RSL-3, an inhibitor of GPX4, could enhance cell ferroptosis and recruit macrophages. Furthermore, inhibiting TEC ferroptosis reduced monocyte chemotactic protein 1 (MCP-1) secretion and macrophage chemotaxis.

CONCLUSIONS

This study uncovers that TEC ferroptosis may promote interstitial fibrosis and inflammation, and targeting ferroptosis may shine a light on protecting against kidney fibrosis in patients with CKDs.

Integrin β3 Induction Promotes Tubular Cell Senescence and Kidney Fibrosis

Tubular cell senescence is a common biologic process and contributes to the progression of chronic kidney disease (CKD); however, the molecular mechanisms regulating tubular cell senescence are poorly understood. Here, we report that integrin β3 (ITGB3) expression was increased in tubular cells and positively correlated with fibrosis degree in CKD patients. ITGB3 overexpression could induce p53 pathway activation and the secretion of TGF-β, which, in turn, resulted in senescent and profibrotic phenotype change in cultured tubular cells. Moreover, according to the CMAP database, we identified isoliquiritigenin (ISL) as an agent to inhibit ITGB3. ISL treatment could suppress Itgb3 expression, attenuate cellular senescence, and prevent renal fibrosis in mice. These results reveal a crucial role for integrin signaling in cellular senescence, potentially identifying a new therapeutic direction for kidney fibrosis.

Complement factor B in high glucose-induced podocyte injury and diabetic kidney disease

The role and mechanisms for upregulating complement factor B (CFB) expression in podocyte dysfunction in diabetic kidney disease (DKD) are not fully understood. Here, analyzing Gene Expression Omnibus GSE30528 data, we identified genes enriched in mTORC1 signaling, CFB, and complement alternative pathways in podocytes from patients with DKD. In mouse models, podocyte mTOR complex 1 (mTORC1) signaling activation was induced, while blockade of mTORC1 signaling reduced CFB upregulation, alternative complement pathway activation, and podocyte injury in the glomeruli. Knocking down CFB remarkably alleviated alternative complement pathway activation and DKD in diabetic mice. In cultured podocytes, high glucose treatment activated mTORC1 signaling, stimulated STAT1 phosphorylation, and upregulated CFB expression, while blockade of mTORC1 or STAT1 signaling abolished high glucose–upregulated CFB expression. Additionally, high glucose levels downregulated protein phosphatase 2Acα (PP2Acα) expression, while PP2Acα deficiency enhanced high glucose–induced mTORC1/STAT1 activation, CFB induction, and podocyte injury. Taken together, these findings uncover a mechanism by which CFB mediates podocyte injury in DKD.

P–568 Homozygous Pathogenic Variants in ACTL9 Cause Fertilization Failure and Male Infertility in Human and Mouse

Study question

What are the other male factors that cause total fertilization failure (TFF) excepting for variants in PLCZ1?

Summary answer

Homozygous variants in ACTL9 (actin like 9) cause abnormal localization of PLCζ in a loosened perinuclear theca (PT) structure and leads to TFF.

What is known already

In previous studies, investigators have reported that the female factors in TFF after intracytoplasmic sperm injection (ICSI) include pathogenic variants in WEE2, TLE6, and TUBB8, whereas for male factors, pathogenic variants in PLCZ1 were reported to be the primary cause of TFF, which account for approximately 30% of couples with male factors in TFF excluding globozoospermia. Most recently, it was reported that pathogenic variants in ACTL7A led to reduced expression and abnormal localization of PLCζ, thereby identifying this genetic variant as a potential cause of TFF.

Study design, size, duration

Fifty-four infertile couples with TFF or poor fertilization (fertilization rate of &lt; 20%) at the Reproductive and Genetic Hospital of CITIC-Xiangya during January 2014 to June 2020 were recruited into this study.

Participants/materials, setting, methods

Male factors were identified in (MOAT). WES analysis was used to analyze the genetic factors of individuals with male factors. Sperm morphological study was conducted by H&E staining and TEM. Immunostaining of PLCζ was used to analyze the status of sperm-borne activation factor. A knock-in mouse model was generated by CRISPER-Cas9 technology. Sperm from homozygous Actl9 variant mice were analyzed by TEM and ICSI. ICSI with AOA was performed in couples with ACTL9 variants.

Main results and the role of chance

A total of 54 couples with TFF or poor fertilization were screened, with 21 couples determined to have a male infertility factor by MOAT. Whole-exome sequencing of these 21 male individuals identified three homozygous pathogenic variants in ACTL9 in three individuals. ACTL9 variations led to abnormal ultrastructure of the PT, with PLCζ absent in the head and present in the neck of the mutant sperm, which contributed to failed normal calcium oscillations in oocytes and subsequent TFF. The key roles of ACTL9 in the PT structure and TFF after ICSI were further confirmed in Actl9-mutated mouse model. Furthermore, assisted oocyte activation by calcium ionophore exposure successfully overcame TFF and achieved live births in a couple with an ACTL9 variant.

Limitations, reasons for caution

The mechanism of how ACTL9 regulate PLCζ remains unknown.

Wider implications of the findings: It provided a genetic marker and a therapeutic option for individuals who have undergone ICSI without successful fertilization.

Trial registration number

not applioable

EUS-guided gastroenterostomy with a lumen apposing self-expandable metallic stent relieves gastric outlet obstruction - a Scandinavian case series

BACKGROUND

EUS-guided gastroenterostomy (EUS-GE) with lumen-apposing metallic stents (LAMS) in patients with gastric outlet obstruction (GOO) has proven to be an alternative to luminal stenting in the duodenum and surgical gastroenterostomy. In severely ill patients, the method can provide improved quality of life (QoL) and symptom relief by restoration of the luminal passage of fluid and nutrients to the small intestine.

AIM

To assess the technical and clinical success and safety of EUS-GE.

MATERIAL AND METHODS

A dual center retrospective case series of 33 consecutive patients with GOO due to malignant (n = 28) or non-malignant conditions (n = 5). The patients were treated with EUS-GE using cautery enhanced LAMS. Procedures were performed guided by EUS and fluoroscopy in general anesthesia or conscious sedation.

RESULTS

Technical success was achieved in all patients. The median procedure time was 71 min and the median hospital stay was three days. Thirty (91%) patients were able to resume oral nutrition after the procedure. Ten patients (30%) experienced adverse events (AEs), including migration of the stent, bleeding, and infection. Four patients had fatal AEs (12%). All stent-related AEs were handled endoscopically. Five patients (15%) needed re-intervention. The median survival time for patients with malignant obstruction was 8.5 weeks (0.5-76), and 13 patients with obstructing malignancies lived 12 weeks or longer.

CONCLUSION

EUS-GE is a minimally invasive and efficient method for restoration of the gastrointestinal passage and may improve palliative care for patients with GOO. The method has potential hazards and should only be offered in expert centers that regularly perform the procedure.

Pyruvate kinase M2 mediates fibroblast proliferation to promote tubular epithelial cell survival in acute kidney injury

Acute kidney injury (AKI) is a devastating condition with high morbidity and mortality rates. The pathological features of AKI are tubular injury, infiltration of inflammatory cells, and impaired vascular integrity. Pyruvate kinase is the final rate-limiting enzyme in the glycolysis pathway. We previously showed that pyruvate kinase M2 (PKM2) plays an important role in regulating the glycolytic reprogramming of fibroblasts in renal interstitial fibrosis. The present study aimed to determine the role of PKM2 in fibroblast activation during the pathogenesis of AKI. We found increased numbers of S100A4 positive cells expressing PKM2 in renal tissues from mice with AKI induced via folic acid or ischemia/reperfusion (I/R). The loss of PKM2 in fibroblasts impaired fibroblast proliferation and promoted tubular epithelial cell death including apoptosis, necroptosis, and ferroptosis. Mechanistically, fibroblasts produced less hepatocyte growth factor (HGF) in response to a loss of PKM2. Moreover, in two AKI mouse models, fibroblast-specific deletion of PKM2 blocked HGF signal activation and aggravated AKI after it was induced in mice via ischemia or folic acid. Fibroblast proliferation mediated by PKM2 elicits pro-survival signals that repress tubular cell death and may help to prevent AKI progression. Fibroblast activation mediated by PKM2 in AKI suggests that targeting PKM2 expression could be a novel strategy for treating AKI.

A compact electron beam ion trap in support of high-temperature plasma diagnostics based on conduction-cooled superconducting coils

Spectroscopic diagnostics of future fusion reactor plasmas require information on impurity line emissions, especially for relevant high-Z metal elements (e.g., tungsten). These materials will be widely used as plasma facing components for their high heat tolerance and low sputtering yield. Based on an electron beam ion trap, a compact impurity spectra platform is developed to mimic the high-temperature environment of a fusion reactor. The proposed platform can deliver a focused e-beam at energies over 30 keV using a confining magnetic field of ∼1.0 T generated by two superconducting coils (NbTi). Cooled by a closed-loop cryocooler, the coils can avoid the usage of a complicated cryogenic system involving the handling of liquid helium. For spectroscopic studies of highly charged ions, a spherically curved crystal spectrometer is proposed to measure a wavelength range around 2-4 Å covering the typical wavelength range expected to be emitted by metal ions in a fusion plasma. This paper reports the design and development progress of the platform.

mTOR Signaling in Kidney Diseases

The mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, is crucial in regulating cell growth, metabolism, proliferation, and survival. Under physiologic conditions, mTOR signaling maintains podocyte and tubular cell homeostasis. In AKI, activation of mTOR signaling in tubular cells and interstitial fibroblasts promotes renal regeneration and repair. However, constitutive activation of mTOR signaling in kidneys results in the initiation and progression of glomerular hypertrophy, interstitial fibrosis, polycystic kidney disease, and renal cell carcinoma. Here, we summarize the recent studies about mTOR signaling in renal physiology and injury, and discuss the possibility of its use as a therapeutic target for kidney diseases.

Assessing adaptation measures on agricultural water productivity under climate change: A case study of Huai River Basin, China

This study explored an integrated framework to assess the effectiveness of adaptation measures on the water productivity (WP) of the agricultural water management (AWM) system in the Huai river basin of China considering climate change impact. The adaptation measures include optimization of cropping pattern (OCP) and upgradation of irrigation techniques (UIT). The delta change method was used to downscale the climate variables from RCP4.5 and RCP8.5 of general circulation models (GCMs) during 2021-2050, the water footprint theory was used to estimate the spatial distribution of blue water to calculate the WP, and the nonlinear optimization model was used to seek optimal cropping pattern aiming at maximizing the system's WP. The changes in WP due to climate change and adaptation measures (e.g. combinations of OCP and UIT) were compared. Results indicated that WP under RCP4.5 and RCP8.5 would be 4.56% and 6.51% lower than those under the benchmark scenario, respectively. The mitigation rates to the negative impact of climate change on WP under RCP4.5 and RCP8.5 would be (1) 3.05% and 3.37% for the combination of spay irrigation technique and OCP, and (2) 4.34% and 4.59% for the combination of drip irrigation technique and OCP, respectively. It was revealed that the combination of drip irrigation and cropping pattern optimization could largely offset the adverse effect from climate change on WP under RCP4.5. Under such a scenario, the total plant areas of wheat and maize would reduce over the basin and so would the net export of crops in the basin; this would lead to a decrease in the crop trade benefit of 7.07 × 10⁹ $ and a relief of 7.50 × 10⁹ m³ of blue water loss. This study results could offer strategic decision support for long-term sustainable AWM of Huai river basin in a changing environment.

Loss of Rictor in tubular cells exaggerates lipopolysaccharide induced renal inflammation and acute kidney injury via Yap/Taz-NF-κB axis

Our previous study demonstrated that the mammalian target of rapamycin complex 2 (mTORC2) signaling alleviates renal inflammation and protects against cisplatin-induced AKI. However, the underlying mechanisms for mTORC2 in regulating renal inflammation in AKI remain to be determined. In this study, we found that lipopolysaccharide (LPS) could activate mTORC2 signaling in NRK-52E cells, and blockage of mTORC2 signaling led to Yap/Taz degradation, which in turn activated NF-κB signaling and induced inflammatory cytokines secretion. Overexpression of constitutively active Taz (Taz-S89A) could attenuate the inflammation-amplified role of mTORC2 blockage. In mouse models, tubule-specific deletion of Rictor had higher blood urea nitrogen level, severe morphological injury as well as more inflammatory cells accumulation compared with those in their littermate controls. Overall, these results demonstrate that mTORC2 signaling protects against renal inflammation and dictates the outcome of AKI by modulating Yap/Taz degradation.

Rheb1 protects against cisplatin-induced tubular cell death and acute kidney injury via maintaining mitochondrial homeostasis

Ras homolog enriched in brain (Rheb1), a small GTPase, plays a crucial role in regulating cell growth, differentiation, and survival. However, the role and mechanisms for Rheb1 in tubular cell survival and acute kidney injury (AKI) remain unexplored. Here we found that Rheb1 signaling was activated in kidney tubule of AKI patients and cisplatin-treated mice. A mouse model of tubule-specific deletion of Rheb1 (Tubule-Rheb1^−/−) was generated. Compared to control littermates, Tubule-Rheb1^−/− mice were phenotypically normal within 2 months after birth but developed more severe kidney dysfunction, tubular cell death including apoptosis, necroptosis and ferroptosis, mitochondrial defect and less PGC-1α expression after cisplatin injection. In primary cultured tubular cells, Rheb1 ablation exacerbated cisplatin-induced cell death and mitochondrial defect. Furthermore, haploinsufficiency for Tsc1 in tubular cells led to Rheb1 activation and mitigated cisplatin-induced cell death, mitochondrial defect and AKI. Together, this study uncovers that Rheb1 may protect against cisplatin-induced tubular cell death and AKI through maintaining mitochondrial homeostasis.

Role of pyruvate kinase M2-mediated metabolic reprogramming during podocyte differentiation

Podocytes, a type of highly specialized epithelial cells, require substantial levels of energy to maintain glomerular integrity and function, but little is known on the regulation of podocytes’ energetics. Lack of metabolic analysis during podocyte development led us to explore the distribution of mitochondrial oxidative phosphorylation and glycolysis, the two major pathways of cell metabolism, in cultured podocytes during in vitro differentiation. Unexpectedly, we observed a stronger glycolytic profile, accompanied by an increased mitochondrial complexity in differentiated podocytes, indicating that mature podocytes boost both glycolysis and mitochondrial metabolism to meet their augmented energy demands. In addition, we found a shift of predominant energy source from anaerobic glycolysis in immature podocyte to oxidative phosphorylation during the differentiation process. Furthermore, we identified a crucial metabolic regulator for podocyte development, pyruvate kinase M2. Pkm2-knockdown podocytes showed dramatic reduction of energy metabolism, resulting in defects of cell differentiation. Meanwhile, podocyte-specific Pkm2-knockout (KO) mice developed worse albuminuria and podocyte injury after adriamycin treatment. We identified mammalian target of rapamycin (mTOR) as a critical regulator of PKM2 during podocyte development. Pharmacological inhibition of mTOR potently abrogated PKM2 expression and disrupted cell differentiation, indicating the existence of metabolic checkpoint that need to be satisfied in order to allow podocyte differentiation.

Tuberous sclerosis 1 (Tsc1) mediated mTORC1 activation promotes glycolysis in tubular epithelial cells in kidney fibrosis

Energy reprogramming to glycolysis is closely associated with the development of chronic kidney disease. As an important negative regulatory factor of the mammalian target of rapamycin complex 1 (mTORC1) signal, tuberous sclerosis complex 1 (Tsc1) is also a key regulatory point of glycolysis. Here, we investigated whether Tsc1 could mediate the progression of kidney interstitial fibrosis by regulating glycolysis in proximal tubular epithelial cells. We induced mTORC1 signal activation in tubular epithelial cells in kidneys with fibrosis via unilateral ureteral occlusion. This resulted in increased tubular epithelial cell proliferation and glycolytic enzyme upregulation. Prior incubation with rapamycin inhibited mTORC1 activation and abolished the enhanced glycolysis and tubular epithelial cell proliferation. Furthermore, knockdown of Tsc1 expression promoted glycolysis in the rat kidney epithelial cell line NRK-52E. Specific deletion of Tsc1 in the proximal tubules of mice resulted in enlarged kidneys characterized by a high proportion of proliferative tubular epithelial cells, dilated tubules with cyst formation, and a large area of interstitial fibrosis in conjunction with elevated glycolysis. Treatment of the mice with the glycolysis inhibitor 2-deoxyglucose notably ameliorated tubular epithelial cell proliferation, cystogenesis, and kidney fibrosis. Thus, our findings suggest that Tsc1-associated mTORC1 signaling mediates the progression of kidney interstitial fibrosis by regulating glycolysis in proximal tubular epithelial cells.

FGF/FGFR2 Protects against Tubular Cell Death and Acute Kidney Injury Involving Erk1/2 Signaling Activation

Background

Fibroblast growth factors (FGFs) are heparin-binding proteins involved in a variety of biological processes, and part of them may act through binding with cell membrane receptor FGFR2.

Objectives

To clarify the role and mechanisms of FGFR2 signaling in tubular cell survival and acute kidney injury (AKI).

Method

In this study, kidney ischemia/reperfusion (IR) or cisplatin injection was used to induce AKI in mice.

Results

In the kidneys after IR or cisplatin injection, the expression of FGFs and Erk1/2 phosphorylation were elevated. To investigate the role of FGFs in tubular cell survival and AKI, a mouse model with tubular cell specific FGFR2 gene disruption was generated. The knockouts were born normal. At 2 months of age, about one-third of the knockouts developed mild hydronephrosis. Ablation of FGFR2 in tubular cells aggravated acute kidney dysfunction as well as tubular cell apoptosis induced by IR or cisplatin. In addition, Erk1/2 phosphorylation was less in the knockout kidneys than in control littermates at day 1 after cisplatin injection. In cultured NRK-52E cells, recombinant FGF2 protein induced Erk1/2 phosphorylation and inhibited cisplatin-induced cell death. PD98059 abolished Erk1/2 phosphorylation and partly reversed the protective effect of FGF2 on cisplatin-induced cell death.

Conclusions

This study indicates that FGF/FGFR2 signaling plays an important role in protecting against tubular cell death and AKI, which is partly through stimulating Erk1/2 activation.

Deletion of FHL2 in fibroblasts attenuates fibroblasts activation and kidney fibrosis via restraining TGF-β1-induced Wnt/β-catenin signaling

Four-and-a-half LIM domains protein 2 (FHL2) has been proposed involving in β-catenin activity. We previously reported that FHL2 mediates TGF-β1-induced tubular epithelial-to-mesenchymal transition through activating Wnt/β-catenin signaling. However, the potential role and mechanism for FHL2 in TGF-β1-induced fibroblast activation and kidney fibrosis remains unknown. Here, we initially observed higher levels of FHL2 expression in fibrotic kidneys from both patients and mice, especially in α-smooth muscle actin (α-SMA)-positive cells in the interstitium. In cultured interstitial fibroblasts, FHL2 expression was induced by TGF-β1. Knockdown of FHL2 remarkably suppressed TGF-β1-induced α-SMA, type I collagen, and fibronectin expression, while overexpression of FHL2 was sufficient to activate fibroblasts. In mice, fibroblast-specific deletion of FHL2 diminished renal induction of α-SMA, type I collagen, and fibronectin and interstitial extracellular matrix deposition at 2 weeks after ureteral obstruction. We next investigated Wnt/β-catenin activity and found that β-catenin was activated in most FHL2-positive cells in renal interstitium from mice with obstructive nephropathy. In vitro, TGF-β1 induced a physical interaction between FHL2 and β-catenin, especially in the nucleus. Downregulation of FHL2 inhibited TGF-β1-induced active β-catenin upregulation, β-catenin nuclear translocation, and β-catenin-mediated transcription, whereas overexpression of FHL2 was able to activate Wnt/β-catenin signaling. FHL2 overexpression-induced β-catenin-mediated gene transcription could be hindered by ICG-001, but FHL2 overexpression-induced upregulation of active β-catenin could not be. Collectively, this study reveals that the signal regulatory effect of FHL2 on β-catenin plays an important role in TGF-β1-induced fibroblast activation and kidney fibrosis.

Manipulating topological transformations of polar structures through real-time observation of the dynamic polarization evolution

Topological structures based on controllable ferroelectric or ferromagnetic domain configurations offer the opportunity to develop microelectronic devices such as high-density memories. Despite the increasing experimental and theoretical insights into various domain structures (such as polar spirals, polar wave, polar vortex) over the past decade, manipulating the topological transformations of polar structures and comprehensively understanding its underlying mechanism remains lacking. By conducting an in-situ non-contact bias technique, here we systematically investigate the real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers at an atomic level. The procedure of vortex pair splitting and the transformation from polar vortex to polar wave and out-of-plane polarization are observed step by step. Furthermore, the redistribution of charge in various topological structures has been demonstrated under an external bias. This provides new insights for the symbiosis of polar and charge and offers an opportunity for a new generation of microelectronic devices.

Direct observation of the dynamic evolution of polar domain structures at atomic level remains challenging. Here, the authors report the observation of real-time topological transformations of polar structures in PbTiO₃/SrTiO₃ multilayers.

Fibroblast mTOR/PPARγ/HGF axis protects against tubular cell death and acute kidney injury

Kidney fibroblasts play a crucial role in dictating tubular cell fate and the outcome of acute kidney injury (AKI). The underlying mechanisms remain to be determined. Here, we found that mTOR signaling was activated in fibroblasts from mouse kidneys with ischemia/reperfusion injury (IRI). Ablation of fibroblast Rheb or Rictor promoted, while ablation of fibroblast Tsc1 protected against tubular cell death and IRI in mice. In tubular cells cultured with conditioned media (CM) from Rheb^-/- or Rictor^-/- fibroblasts, less hepatocyte growth factor (HGF) receptor c-met signaling activation or staurosporine-induced cell apoptosis was observed. While CM from Tsc1^-/- fibroblasts promoted tubular cell c-met signaling activation and inhibited staurosporine-induced cell apoptosis. In kidney fibroblasts, blocking mTOR signaling downregulated the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and HGF. Downregulating fibroblast HGF expression or blocking tubular cell c-met signaling facilitated tubular cell apoptosis. Notably, renal PPARγ and HGF expression was less in mice with fibroblast Rheb or Rictor ablation, but more in mice with fibroblast Tsc1 ablation than their littermate controls, respectively. Together, these data suggest that mTOR signaling activation in kidney fibroblasts protects against tubular cell death and dictates the outcome of AKI through stimulating PPARγ and HGF expression.

Optical creation of a supercrystal with three-dimensional nanoscale periodicity

Stimulation with ultrafast light pulses can realize and manipulate states of matter with emergent structural, electronic and magnetic phenomena. However, these non-equilibrium phases are often transient and the challenge is to stabilize them as persistent states. Here, we show that atomic-scale PbTiO₃/SrTiO₃ superlattices, counterpoising strain and polarization states in alternate layers, are converted by sub-picosecond optical pulses to a supercrystal phase. This phase persists indefinitely under ambient conditions, has not been created via equilibrium routes, and can be erased by heating. X-ray scattering and microscopy show this unusual phase consists of a coherent three-dimensional structure with polar, strain and charge-ordering periodicities of up to 30 nm. By adjusting only dielectric properties, the phase-field model describes this emergent phase as a photo-induced charge-stabilized supercrystal formed from a two-phase equilibrium state. Our results demonstrate opportunities for light-activated pathways to thermally inaccessible and emergent metastable states.

Intracellular manipulation and measurement with multipole magnetic tweezers

The capability to directly interrogate intracellular structures inside a single cell for measurement and manipulation is important for understanding subcellular and suborganelle activities, diagnosing diseases, and developing new therapeutic approaches. Compared with measurements of single cells, physical measurement and manipulation of subcellular structures and organelles remain underexplored. To improve intracellular physical measurement and manipulation, we have developed a multipole magnetic tweezers system for micromanipulation involving submicrometer position control and piconewton force control of a submicrometer magnetic bead inside a single cell for measurement in different locations (spatial) and different time points (temporal). The bead was three-dimensionally positioned in the cell using a generalized predictive controller that addresses the control challenge caused by the low bandwidth of visual feedback from high-resolution confocal imaging. The average positioning error was quantified to be 0.4 μm, slightly larger than the Brownian motion–imposed constraint (0.31 μm). The system is also capable of applying a force up to 60 pN with a resolution of 4 pN for a period of time longer than 30 min. The measurement results revealed that significantly higher stiffness exists in the nucleus’ major axis than in the minor axis. This stiffness polarity is likely attributed to the aligned actin filament. We also showed that the nucleus stiffens upon the application of an intracellularly applied force, which can be attributed to the response of structural protein lamin A/C and the intracellular stress fiber actin filaments.

The signaling protein Wnt5a promotes TGFβ1-mediated macrophage polarization and kidney fibrosis by inducing the transcriptional regulators Yap/Taz

M2 macrophage polarization is known to underlie kidney fibrosis. We previously reported that most of the members of the Wnt family of signaling proteins are induced in fibrotic kidneys. Dysregulation of the signaling protein Wnt5a is associated with fibrosis, but little is known about the role of Wnt5a in regulating M2 macrophage activation that results in kidney fibrosis. Here, using murine Raw 264.7 cells and bone marrow-derived macrophages, we found that Wnt5a enhanced transforming growth factor β1 (TGFβ1)-induced macrophage M2 polarization as well as expression of the transcriptional regulators Yes-associated protein (Yap)/transcriptional coactivator with PDZ-binding motif (Taz). Verteporfin blockade of Yap/Taz inhibited both Wnt5a- and TGFβ1-induced macrophage M2 polarization. In mouse models of kidney fibrosis, shRNA-mediated knockdown of Wnt5a expression diminished kidney fibrosis, macrophage Yap/Taz expression, and M2 polarization. Moreover, genetic ablation of Taz in macrophages attenuated kidney fibrosis and macrophage M2 polarization in mice. Collectively, these results indicate that Wnt5a promotes kidney fibrosis by stimulating Yap/Taz-mediated macrophage M2 polarization.

PDE/cAMP/Epac/C/EBP-β Signaling Cascade Regulates Mitochondria Biogenesis of Tubular Epithelial Cells in Renal Fibrosis

AIMS

Cyclic adenosine 3'5'-monophosphate (cAMP) is a universal second messenger that plays an important role in intracellular signal transduction. cAMP is synthesized by adenylate cyclases from adenosine triphosphate and terminated by the phosphodiesterases (PDEs). In the present study, we investigated the role of the cAMP pathway in tubular epithelial cell mitochondrial biogenesis in the pathogenesis of renal fibrosis.

RESULTS

We found that the cAMP levels were decreased in fibrotic kidney tissues, and replenishing cAMP could ameliorate tubular atrophy and extracellular matrix deposition. The downregulation of cAMP was mainly attributed to the increased PDE4 expression in tubular epithelial cells. The inhibition of PDE4 by PDE4 siRNA or the specific inhibitor, rolipram, attenuated unilateral ureteral obstruction-induced renal interstitial fibrosis and transforming growth factor (TGF)-β1-stimulated primary tubular epithelial cell (PTC) damage. The Epac1/Rap1 pathway contributed to the main effect of cAMP on renal fibrosis. Rolipram could restore C/EBP-β and PGC-1α expression and protect the mitochondrial function and structure of PTCs under TGF-β1 stimulation. The antifibrotic role of rolipram in renal fibrosis relies on C/EBP-β and PGC-1α expression in tubular epithelial cells. Innovation and Conclusion: The results of the present study indicate that cAMP signaling regulates the mitochondrial biogenesis of tubular epithelial cells in renal fibrosis. Restoring cAMP by the PDE4 inhibitor rolipram may ameliorate renal fibrosis by targeting C/EBP-β/PGC1-α and mitochondrial biogenesis. Antioxid. Redox Signal. 29, 637-652.

Yap/Taz mediates mTORC2-stimulated fibroblast activation and kidney fibrosis

Our previously published study demonstrated that mammalian target of rapamycin complex 2 (mTORC2) signaling mediates TGFβ1-induced fibroblast activation. However, the underlying mechanisms for mTORC2 in stimulating fibroblast activation remain poorly understood. Here, we found that TGFβ1 could stimulate mTORC2 and Yap/Taz activation in NRK-49F cells. Blocking either mTORC2 or Yap/Taz signaling diminished TGFβ1-induced fibroblast activation. In addition, blockade of mTORC2 could down-regulate the expression of Yap/Taz, connective tissue growth factor (CTGF), and ankyrin repeat domain 1 (ANKRD1). Overexpression of constitutively active Taz (Taz-S89A) could restore fibroblast activation suppressed by PP242, an mTOR kinase inhibitor in NRK-49F cells. In mouse kidneys with unilateral ureter obstructive (UUO) nephropathy, both mTORC2 and Yap/Taz were activated in the interstitial myofibroblasts. Ablation of Rictor in fibroblasts/pericytes or blockade of mTOR signaling with PP242 attenuated Yap/Taz activation and UUO nephropathy in mice. Together, this study uncovers that targeting mTORC2 retards fibroblast activation and kidney fibrosis through suppressing Yap/Taz activation.

Protein kinase Cα drives fibroblast activation and kidney fibrosis by stimulating autophagic flux

Kidney fibrosis is a histological hallmark of chronic kidney disease and arises in large part through extracellular matrix deposition by activated fibroblasts. The signaling protein complex mTOR complex 2 (mTORC2) plays a critical role in fibroblast activation and kidney fibrosis. Protein kinase Cα (PKCα) is one of the major sub-pathways of mTORC2, but its role in fibroblast activation and kidney fibrosis remains to be determined. Here, we found that transforming growth factor β1 (TGFβ1) activates PKCα signaling in cultured NRK-49F cells in a time-dependent manner. Blocking PKCα signaling with the chemical inhibitor Go6976 or by transfection with PKCα siRNA largely reduced expression of the autophagy-associated protein lysosomal-associated membrane protein 2 (LAMP2) and also inhibited autophagosome-lysosome fusion and autophagic flux in the cells. Similarly to chloroquine, Go6976 treatment and PKCα siRNA transfection also markedly inhibited TGFβ1-induced fibroblast activation. In murine fibrotic kidneys with unilateral ureteral obstruction (UUO) nephropathy, PKCα signaling is activated in the interstitial myofibroblasts. Go6976 administration largely blocked autophagic flux in fibroblasts in the fibrotic kidneys and attenuated the UUO nephropathy. Together, our findings suggest that blocking PKCα activity may retard autophagic flux and thereby prevent fibroblast activation and kidney fibrosis.

Canonical Wnt Signaling Promotes Macrophage Proliferation during Kidney Fibrosis

Background

Wnt/β-catenin, an evolutionary conserved signaling pathway, plays an essential role in modulating kidney injury and repair. Our previous studies demonstrated that Wnt/β-catenin signaling could stimulate macrophage M2 polarization and contribute to kidney fibrosis. However, whether canonical Wnt signaling activation leads to macrophage proliferation during kidney fibrosis remains to be determined.

Methods

In this study, a mouse model with macrophage-specific β-catenin gene deletion was generated and a unilateral ureter obstruction (UUO) model was created.

Results

In a mouse model with UUO nephropathy, deletion of β-catenin in macrophages attenuated macrophage proliferation and accumulation in kidney tissue. Wnt3a, a well-known canonical Wnt signaling stimulator, could markedly promote macrophage proliferation, whereas blocking canonical Wnt signaling with ICG-001 or ablating β-catenin could largely inhibit macrophage colony-stimulating factor-stimulated macrophage proliferation. Wnt3a treatment could time-dependently upregulate cyclin D1 protein expression and blocking β-catenin signaling could downregulate it.

Conclusion

These results demonstrate that Wnt/ β-catenin signaling is essential for promoting macrophage proliferation during kidney fibrosis.

The feedback loop between miR-21, PDCD4 and AP-1 functions as a driving force for renal fibrogenesis

Renal fibrosis is a final common pathway of chronic kidney disease. Sustained activation of fibroblasts is considered to play a key role in perpetuating renal fibrosis but the driving force in the perpetuation stage is only partially understood. To date, some investigations have specifically identified overexpression of microRNA 21 (miR-21) in the progression of kidney fibrosis. Nevertheless, the precise role of miR-21 in fibroblast activation remains largely unknown. In this study, we found that miR-21 was significantly upregulated in activated fibroblasts and that it maintained itself at constant high levels by employing an auto-regulatory loop between miR-21, PDCD4 and AP-1. Persistently upregulated miR-21 suppressed protein expression of Smad7 and, eventually, enhanced the TGF-β1/Smad pathway to promote fibroblast activation. More importantly, we found miR-21 sequestration with miR-21 antagomir or AP-1 inhibitors attenuated unilateral ureteral obstruction (UUO)-induced renal fibrosis. miR-21-knockout mice also suffered far less interstitial fibrosis in response to kidney injury. Altogether, these data suggest that miR-21 is a main driving force of fibroblast activation and keeps its high expression level by employing a double negative autoregulatory loop. Targeting this aberrantly activated feedback loop may provide new therapeutic strategy in treating fibrotic kidneys.

Identification of macrophage-related candidate genes in lupus nephritis using bioinformatics analysis

Lupus nephritis (LN) is a chronic autoimmune disorder. Here we try to identify the candidate genes in macrophages related to LN. We performed a systematic search in the Gene Expression Omnibus (GEO) database for microarray in human mononuclear cells and mouse macrophages of LN. The results of clustering and venn analysis of different GEO datasets showed that 8 genes were up-regulated and 2 genes down-regulated in samples from both human and mouse LN. The data from gene network and GO analysis revealed that CD38 and CCL2 were localized in the core of the network. Immunofluorescence staining showed that CD38 expression was markedly increased in macrophages from kidneys with LN. Our study identifies the gene expression profile for macrophages and demonstrated the induction of CCL2 and CD38 in macrophages from patients with LN. However, regarding the limited patient number included in this study, the results are preliminary and more studies are still needed to further decipher the macrophage-related candidate genes for the pathogenesis of LN.

FHL2 promotes tubular epithelial-to-mesenchymal transition through modulating β-catenin signalling

β-Catenin signalling plays an important role in regulating tubular epithelial-to-mesenchymal transition (EMT), an indispensable programme for driving renal fibrosis. As an adapter protein, four and a half LIM domain protein 2 (FHL2) acts as a coregulator of β-catenin in several other cell types. To determine whether FHL2 affects β-catenin signalling and thus is involved in tubular EMT, we examined its expression and function in the process of TGF-β1-induced EMT. FHL2 mRNA and protein were induced by TGF-β1 in rat tubular epithelial cells (NRK-52E), an effect that intracellular Smad signalling was required. Ectopic expression of FHL2 inhibited E-cadherin and enhanced α-smooth muscle actin (α-SMA) and fibronectin expression, whereas knockdown of FHL2 partially restored E-cadherin and reduced α-SMA and fibronectin induction stimulated by TGF-β1. Overexpression of FHL2 increased β-catenin dephosphorylation (Ser37/Thr41), nuclear translocation and β-catenin-mediated transcription and up-regulated expression of β-catenin target, EMT-related genes, such as Snail, Twist, vimentin, plasminogen activator inhibitor-1 and matrix metalloproteinase-7. Conversely, knockdown of FHL2 increased β-catenin phosphorylation (Ser33/37/Thr41), decreased its nuclear translocation and inhibited β-catenin-mediated transcription and target genes expression. TGF-β1 induced a FHL2/β-catenin interaction in NRK-52E cells, especially in the nuclei. In a mouse model of obstructive nephropathy, FHL2 mRNA and protein were induced in a time-dependent fashion, and the extent and pattern of renal β-catenin activation were positively correlated with FHL2 induction. Collectively, this study suggests that FHL2, via modulating β-catenin signalling, may implicate in regulation of TGF-β1-mediated tubular EMT and could be a potential therapeutic target for fibrotic kidney disease.

Ablation of FGFR2 in Fibroblasts Ameliorates Kidney Fibrosis after Ischemia/Reperfusion Injury in Mice

Background

Fibroblast growth factors (FGFs) are heparin-binding proteins involved in a variety of biological processes. However, the role and mechanisms of FGF/FGFR2 signaling in fibroblast activation and kidney fibrosis need further investigation.

Methods

In this study, a mouse model with fibroblast-specific FGFR2 gene disruption was generated. The knockouts were born normal and no kidney dysfunction or histological abnormality was found within 2 months after birth. A kidney ischemia/reperfusion injury (IRI) model was created.

Results

Kidney fibrosis was developed in the control littermates within 2 and 4 weeks after IRI, while in the knockouts, total collagen deposition, fibronectin, and alpha smooth muscle actin expression were decreased compared to those in the control littermates. In addition, the numbers of Ki-67-positive interstitial cells as well as TUNEL-positive interstitial cells were lower in the knockout kidneys at 4 weeks after IRI. Phosphorylated extracellular regulated protein kinase 1/2 was decreased in the knockout kidneys at 2 and 4 weeks after IRI compared to those in the control littermates.

Conclusion

These results suggest that FGF/FGFR2 signaling may promote the proliferation and activation of kidney fibroblasts, which contribute to the development of kidney fibrosis.