Mineralocorticoid receptor (MR) antagonist eplerenone and MR modulator balcinrenone prevent renal extracellular matrix remodeling and inflammation via the MR/proteoglycan/TLR4 pathway.

Excessive activation of the mineralocorticoid receptor (MR) is implicated in cardiovascular and renal disease. Decreasing MR activation with MR antagonists (MRA) is effective to slow chronic kidney disease (CKD) progression and its cardiovascular comorbidities in animal models and patients. The present study evaluates the effects of the MR modulator balcinrenone and the MRA eplerenone on kidney damage in a metabolic CKD mouse model combining nephron reduction and a 60% high fat diet. Balcinrenone and eplerenone prevented the progression of renal damages, extracellular matrix remodeling and inflammation to a similar extent. We identified a novel mechanism linking MR activation to the renal proteoglycan deposition and inflammation via the TLR4 pathway activation. Balcinrenone and eplerenone similarly blunted this pathway activation.

Liraglutide combined with routine therapy improves renal function, renal fibrosis, immune status, and prognosis of type 2 diabetes patients.

OBJECTIVE: To investigate the effect of Liraglutide in conjunction with routine therapy on renal function, renal fibrosis, immune status, and prognosis in patients with diabetes mellitus. METHODS: The clinical data of patients with Type 2 diabetes mellitus (T2DM) treated at the First Affiliated Hospital of Jishou University from March 2021 to March 2022 were retrospectively analyzed. Patients were assigned into a control group (n=42) and a study group (n=42) according to their treatment regimen. The control group received routine treatment, and the study group received Liraglutide in addition to routine treatment. The therapeutic effects, blood glucose levels, renal function, renal fibrosis, and Immunoglobulin (Ig) levels as well as the incidence of adverse reactions, were compared between the two groups. RESULTS: The effective rate was higher in study group (97.62%) than that of the control group (78.57%) (P<0.05). After treatment, the fasting blood-glucose (FBG), 2-hour postprandial plasma glucose (2hPG), and glycosylated hemoglobin (HbA1c) levels were decreased; and the study group displayed a significantly lower blood glucose level than the control group (all P<0.05). Also, the serum creatinine (Scr), blood urea nitrogen (BUN), and 24-hour urinary protein quantification (24h-UPor) were decreased after treatment; and the study group showed more pronounced improvement in renal function index than did the control group (all P<0.05). The levels of IgA, IgM, and IgG were increased after treatment compared to pre-treatment; and the study group exhibited significantly better improvement than the control group (all P<0.05). However, the study group reported a notably higher incidence of adverse reactions than the control group (19.05% vs 2.38%; P<0.05). CONCLUSION: Liraglutide combined with routine therapy is effective in treating patients with diabetes, which can effectively reduce the levels of blood glucose andurinary protein, and the degree of renal fibrosis, while improving renal and immune functions and the clinical prognosis of diabetic patients.

Novel glucomannan-like polysaccharide from Lycium barbarum L. ameliorates renal fibrosis via blocking macrophage-to-myofibroblasts transition.

The macrophage to myofibroblasts transition (MMT) has been reported as a newly key target in renal fibrosis. Lycium barbarum L. is a traditional Chinese medicine for improving renal function, in which its polysaccharides (LBPs) are the mainly active components. However, whether the role of LBPs in treating renal fibrosis is related to MMT process remain unclear. The purpose of this study was to explore the relationship between the regulating effect on MMT process and the anti-fibrotic effect of LBPs. Initially, small molecular weight LBPs fractions (LBP-S) were firstly isolated via Sephadex G-100 column. Then, the potent inhibitory effect of LBP-S on MMT process was revealed on bone marrow-derived macrophages (BMDM) model induced by TGF-ß. Subsequently, the chemical structure of LBP-S was elucidated through monosaccharide, methylation and NMR spectrum analysis. In vivo biodistribution characteristics studies demonstrated that LBP-S exhibited effectively accumulation in kidney via intraperitoneal administration. Finally, LBP-S showed a satisfactory anti-renal fibrotic effect on unilateral ureteral obstruction operation (UUO) mice, which was significantly reduced following macrophage depletion. Overall, our findings indicated that LPB-S could alleviate renal fibrosis through regulating MMT process and providing new candidate agents for chronic kidney disease (CKD) related fibrosis treatment.

Cannabinoid receptor 2 plays a key role in renal fibrosis through inhibiting lipid metabolism in renal tubular cells.

AIMS: Renal fibrosis is a common feature in various chronic kidney diseases (CKD). Tubular cell damage is a main characterization which results from dysregulated fatty acid oxidation (FAO) and lipid accumulation. Cannabinoid Receptor 2 (CB2) contributes to renal fibrosis, however, its role in FAO dysregulation in tubular cells is not clarified. In this study, we found CB2 plays a detrimental role in lipid metabolism in tubular cells. METHODS: CB2 knockout mice were adopted to establish a folic acid-induced nephropathy (FAN) model. CB2-induced FAO dysfunction, lipid deposition, and fibrogenesis were assessed in vivo and vitro. To explore molecular mechanisms, ß-catenin inhibitors and peroxisome proliferator-activated receptor alpha (PPARα) activators were also used in CB2-overexpressed cells. The mediative role of ß-catenin in CB2-inhibited PPARα and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) activation was analyzed. RESULTS: CB2 activates ß-catenin signaling, resulting in the suppression of PPARα/PGC-1α axis. This decreased FAO functions and led to lipid droplet formation in tubular cells. CB2 gene ablation effectively mitigated FAO dysfunction, lipid deposition and uremic toxins accumulation in FAN mice, consequently retarding renal fibrosis. Additionally, inhibition to ß-catenin or PPARα activation could greatly inhibit lipid accumulation and fibrogenesis induced by CB2. CONCLUSIONS: This study highlights CB2 disrupts FAO in tubular cells through ß-catenin activation and subsequent inhibition on PPARα/PGC-1α activity. Targeted inhibition on CB2 offers a perspective therapeutic strategy to fight against renal fibrosis.

Dyslipidemia-induced renal fibrosis related to ferroptosis and endoplasmic reticulum stress.

Dyslipidemia may induce chronic kidney disease and trigger both ferroptosis and endoplasmic reticulum (ER) stress, but the instigating factors are incompletely understood. We tested the hypothesis that different models of dyslipidemia engage distinct kidney injury mechanisms. Wild-type (WT) or proprotein-convertase subtilisin/kexin type-9 (PCSK9)-gain-of-function (GOF) Ossabaw pigs were fed with a 6-months normal (ND) or high-fat (HFD) diet (n=5-6 each). Renal function and fat deposition were studied in-vivo using CT, and blood and kidney tissue studied ex-vivo for lipid profile, systemic and renal vein free fatty acids (FFA) levels, and renal injury mechanisms including lipid peroxidation (LPO), ferroptosis, and ER stress. Compared with WT-ND pigs, both HFD and PCSK9-GOF elevated triglyceride levels, which were highest in WT-HFD, whereas total and low-density lipoprotein (LDL) cholesterol levels rose only in PCSK9-GOF pigs, particularly in PCSK9-GOF/HFD. The HFD groups had worse kidney function than ND. The WT-HFD kidneys retained more FFA than other groups, but all kidneys developed fibrosis. Furthermore, HFD-induced ferroptosis in WT-HFD indicated by increased free iron, and LPO, and decreased glutathione peroxidase-4 mRNA expression, while PCSK9-GOF induced ER stress with upregulated GRP94 and CHOP protein expression. In vitro, PK1 cells treated with palmitic acid (PA) and oxidized-LDL to mimic HFD and PCSK9-GOF showed similar trends to those observed in vivo. Taken together, HFD-induced hypertriglyceridemia promotes renal FFA retention and ferroptosis, whereas PCSK9-GOF-induced hypercholesterolemia elicits ER stress, both resulting in renal fibrosis. These observations suggest different targets for preventing and treating renal fibrosis in subjects with specific types of dyslipidemia.

The association between renal medullary and cortical fibrosis, stiffness, and concentrating capacity: an observational, single-center cross-sectional study.

BACKGROUND: Fibrosis is a common final pathway leading to end-stage renal failure. As the renal medulla and cortex contain different nephron segments, we analyzed the factors associated with the progression of renal medullary and cortical fibrosis. METHODS: A total of 120 patients who underwent renal biopsy at Kawashima Hospital between May 2019 and October 2022 were enrolled in this retrospective study. Renal medullary and cortical fibrosis and stiffness were evaluated using Masson's trichrome staining and shear wave elastography, respectively. Maximum urine osmolality in the Fishberg concentration test was also examined. RESULTS: Medullary fibrosis was positively correlated with cortical fibrosis (p < 0.0001) and log-converted urinary ß2-microglobulin (MG) (log urinary ß2-MG) (p = 0.022) and negatively correlated with estimated glomerular filtration rate (eGFR) (p = 0.0002). Cortical fibrosis also correlated with log urinary ß2-MG, eGFR, and maximum urine osmolality. Multivariate analysis revealed that cortical fibrosis levels (odds ratio [OR]: 1.063) and medullary stiffness (OR: 1.089) were significantly associated with medullar fibrosis (≧45%). The severe fibrosis group with both medullary fibrosis (≧45%) and cortical fibrosis (≧25%) had lower eGFR and maximum urine osmolality values and higher urinary ß2-MG levels than the other groups. CONCLUSIONS: Patients with disorders involving both renal medullary and cortical fibrosis had decreased maximum urine osmolality but had no abnormalities in the urinary concentrating capacities with either condition. Renal medullary and cortical fibrosis were positively correlated with urinary ß2-MG, but not with urinary N-acetyl-beta-D-glucosaminidase.

Pirfenidone inhibits TGF-ß1-induced fibrosis via downregulation of Smad and ERK pathway in MDCK cells.

The prevalence of chronic kidney disease (CKD) in dogs increases with age, and renal fibrosis is an important pathophysiological mechanism in this process. However, only a few drugs that can effectively inhibit fibrosis in the kidneys of dogs are currently available. In this study, we aimed to determine whether pirfenidone, a drug that has shown antifibrotic effects in various clinical studies, also exerts antifibrotic effects on canine renal tubular epithelial cells, Madin-Darby canine kidney cells (MDCK). To this end, we treated MDCK cells with various concentrations of pirfenidone, followed by transforming growth factor-beta1 (TGF-ß1) to stimulate fibrotic conditions. A cell viability assay was performed to determine the effect of pirfenidone on cell survival. Fibrosis-related markers and TGF-ß1 fibrotic pathway-related markers were assessed using qPCR, Western blot analysis and immunocytochemistry. A one-way analysis of variance (ANOVA) was performed, followed by Tukey's post-hoc test for multiple comparisons. Pirfenidone treatment significantly reduced the expression of profibrotic markers such as α-smooth muscle actin, fibronectin, and collagen. Additionally, it upregulated the expression of E-cadherin, an epithelial marker. Furthermore, pirfenidone effectively inhibited the phosphorylation of key factors involved in the TGF-ß1 signaling pathway, including Smad2/3 and ERK1/2. These results demonstrate that pirfenidone suppresses TGF-ß1-induced fibrosis in MDCK cells by attenuating epithelial-mesenchymal transition and the relevant signaling pathways.

Nuclear receptor 4A1 ameliorates renal fibrosis by inhibiting vascular endothelial growth factor A induced angiogenesis in UUO rats.

INTRODUCTION: Angiogenesis is closely related to renal fibrosis; however, its basic mechanism remains unclear. In our study, we found that nuclear receptor 4A1 (NR4A1) inhibits vascular endothelial growth factor A (VEGFA)-induced angiogenesis, ameliorating renal fibrosis. METHODS: We prepared a renal fibrosis animal model with unilateral ureteral obstruction (UUO) and NR4A1 knockdown UUO mice model, Using Human umbilical vein endothelial cells (HUVECs) to conduct all in vitro experiments. We then detected and analyzed the expression levels of NR4A1 and other genes related to angiogenesis and fibrosis. RESULTS: The angiogenesis related genes, such as VEGFA, vascular endothelial growth factor receptor-2 (VEGFR-2), endoglin (CD105), as well as the expression of fibrosis related genes that included, α-smooth muscle actin (α-SMA), Vimentin, and Collagen I are all significantly increased in the UUO rat model. In addition, the expression of NR4A1 of the kidney tissue of UUO rats was significantly reduced. Therefore, according to the above results, we speculated that angiogenesis may exacerbate renal fibrosis and NR4A1 may repress renal fibrosis by inhibiting angiogenesis. To further verify the above results, we used VEGFA to stimulate HUVECs with (or without) overexpression or knockdown of NR4A1. The results showed that with prolonged stimulation using VEGFA, the expression of NR4A1 decreases. Overexpression of NR4A1 significantly inhibits the expression of related indicators of angiogenesis and renal fibrosis. Furthermore, knockdown of NR4A1 induces endothelial cell proliferation and migration; therefore, exacerbating angiogenesis and fibrosis. Finally, the results of NR4A1 knockdown UUO mice showed that knockdown of NR4A1 can aggravating kidney damage and induce the expression of angiogenesis and renal fibrosis related indicators, while UUO can significantly induce kidney damage, angiogenesis and renal fibrosis. When knockdown of NR4A1, renal kidney damage, angiogenesis and fibrosis becomes more severe than UUO. Thus, all of these results indicate that NR4A1 can ameliorate renal fibrosis by inhibiting angiogenesis. CONCLUSIONS: NR4A1 can inhibit angiogenesis to ameliorate renal fibrosis.

Mechanistic study on lncRNA XIST/miR-124-3p/ITGB1 axis in renal fibrosis in obstructive nephropathy.

OBJECTIVE: The purpose of this study was to investigate the role and possible mechanism of lncRNA XIST in renal fibrosis and to provide potential endogenous targets for renal fibrosis in obstructive nephropathy (ON). METHODS: The study included 50 cases of ON with renal fibrosis (samples taken from patients undergoing nephrectomy due to ON) and 50 cases of normal renal tissue (samples taken from patients undergoing total or partial nephrectomy due to accidental injury, congenital malformations, and benign tumors). Treatment of human proximal renal tubular epithelium (HK-2) cells with TGF-ß1 simulated renal fibrosis in vitro. Cell viability and proliferation were measured by CCK-8 and EdU, and cell migration was measured by transwell. XIST, miR-124-3p, ITGB1, and epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin, α-SMA, and fibronectin) were detected by PCR and immunoblot. The targeting relationship between miR-124-3p and XIST or ITGB1 was verified by starBase and dual luciferase reporter gene experiments. In addition, The left ureter was ligated in mice as a model of unilateral ureteral obstruction (UUO), and the renal histopathology was observed by HE staining and Masson staining. RESULTS: ON patients with renal fibrosis had elevated XIST and ITGB1 levels and reduced miR-124-3p levels. The administration of TGF-ß1 exhibited a dose-dependent promotion of HK-2 cell viability, proliferation, migration, and EMT. Conversely, depleting XIST or enhancing miR-124-3p hindered HK-2 cell viability, proliferation, migration, and EMT in TGF-ß1-damaged HK-2 cells HK-2 cells. XIST functioned as a miR-124-3p sponge. Additionally, miR-124-3p negatively regulated ITGB1 expression. Elevating ITGB1 weakened the impact of XIST depletion on TGF-ß1-damaged HK-2 cells. Down-regulating XIST improved renal fibrosis in UUO mice. CONCLUSION: XIST promotes renal fibrosis in ON by elevating miR-124-3p and reducing ITGB1 expressions.

The role of protein prenylation inhibition through targeting FPPS by zoledronic acid in the prevention of renal fibrosis in rats.

Renal fibrosis (RF) represents the most widespread pathological condition in chronic kidney disease (CKD). Recently, protein prenylation has been implicated in the fibrosis's progression. The research examined the renoprotective effect of zoledronic acid (ZA) (50 µg/kg/week) in a rat model of carbon tetrachloride (CCl4)-induced RF through targeting protein prenylation. Forty Wistar male rats were split up into the control group, vehicle-treated group, model-RF group, and RF-ZA group. Mean arterial blood pressure (MBP), BUN, serum creatinine, and urine albumin-creatinine ratio (uACR), protein levels of farnesyl pyrophosphate (FPP), tumour necrosis factor-alpha (TNF-α), transforming growth factor-ß (TGF-ß), and malondialdehyde (MDA), and catalase and gene expression of farnesyl pyrophosphate synthase (FPPS) and nuclear factor-kB (NF-κB) were measured. Immunohistochemical staining for renal interleukin-6 (IL-6), α-smooth muscle actin (α-SMA), and caspase-3, as well as histopathological alterations, were assessed. ZA considerably ceased the reduction in MBP, markedly reduced uACR, serum creatinine, BUN, and expression of FPPS, FPP, NF-κB, TGF-ß, TNF-α, and MDA, and significantly increased catalase levels compared to the model-RF rats. ZA ameliorated the CCl4-induced histopathological alterations and suppressed the expression of caspase-3, α-SMA, and IL-6. In conclusion, ZA preserved renal function and prevented renal fibrosis in a rat model. These were achieved through targeting protein prenylation mainly by inhibiting FPPS.

Enhanced eNOS/nitric oxide production by nebivolol interferes with TGF-ß1/Smad3 signaling and collagen I deposition in the kidney after prolonged tacrolimus administration.

AIMS: Tacrolimus is an effective immunosuppressant commonly used post-transplantation and in certain autoimmune diseases. However, its long-term administration is associated with renal fibrosis through transforming growth factor-beta/suppressor of mother against decapentaplegic (TGF-ß/Smad) signaling that could be partly attributed to endothelial dysfunction alongside decreased nitric oxide (NO) release. Our study aimed to investigate the prospective renal anti-fibrotic effect of enhanced NO production by nebivolol against tacrolimus stimulated TGF-ß1/Smad3 signaling. MATERIALS AND METHODS: To illustrate the proposed mechanism of nebivolol, Nω-nitro-L-arginine methyl ester (L-NAME); nitric oxide synthase inhibitor; was co-administrated with nebivolol. Rats were treated for 30 days as control, tacrolimus, tacrolimus/nebivolol, tacrolimus/L-NAME, and tacrolimus/nebivolol/L-NAME groups. KEY FINDINGS: Our results revealed that renal NO content was reduced in tacrolimus-treated rats, while treatment with tacrolimus/nebivolol enhanced NO content via up-regulated endothelial nitric oxide synthase (eNOS), but down-regulated inducible nitric oxide synthase (iNOS) expression. That participated in the inhibition of TGF-ß1/Smad3 signaling induced by tacrolimus, where the addition of L-NAME abolished the effects of nebivolol. Subsequently, the deposition of collagen I and alpha-smooth muscle actin (α-SMA) was retarded by nebivolol, emphasized by reduced Masson's Trichrome staining. In accordance, there was a strong negative correlation between eNOS and both TGF-ß1 and collagen I protein expression. The protective effects of nebivolol were further confirmed by the improvement in kidney function biomarkers and histological features. SIGNIFICANCE: It can be suggested that treatment with nebivolol along with tacrolimus could effectively suppress renal TGF-ß1/Smad3 fibrotic signaling via the enhancement of endothelial NO production, thus curbing renal fibrosis development.

New Ethylated Derivatives of Sulfur- and Nitrogen-Containing Artifacts from Tenodera sinensis Egg Pod and Their Anti-Renal Fibrosis.

Three pairs of enantiomers and one achiral molecule that are new ethylated derivatives of sulfur and nitrogen-containing compounds named mantidisamides E-H (1-4), along with twenty known ones (5-24), were derived from the ethanol extract of Tenodera sinensis Saussure. The structures of these new compounds and their absolute configurations were assigned on the basis of spectroscopic analyses and computational methods. The assessment of activities in NRK-52e cells induced by TGF-ß1 demonstrated that the previously undescribed compounds 1 and 2 exhibited a significant capacity to inhibit the expression of proteins (fibronectin, collagen I, and α-SMA). Moreover, the biological activity of these compounds was found to increase with rising concentrations. Notably, compounds 1-4 should be artifacts; however, undescribed compounds 1 and 2, which possessed obvious biological activity, might be attractive for chemists and biologists due to the potential for more detailed exploration of their properties. It is worth mentioning that compounds 1 and 2 remain novel structures even in the absence of the ethoxy group.

Endothelial Birc3 promotes renal fibrosis through modulating Drp1-mediated mitochondrial fission via MAPK/PI3K/Akt pathway.

Renal fibrosis serves as the shared pathway in chronic kidney disease (CKD) progression towards end-stage renal disease (ESRD). Endothelial-mesenchymal transition (EndMT) is a vital mechanism leading to the generation of myofibroblasts, thereby contributing to the advancement of fibrogenesis. Baculoviral IAP Repeat Containing 3(Birc3) was identified as a crucial inhibitor of cell death and a significant mediator in inflammatory signaling and immunity. However, its involvement in the development of renal interstitial fibrosis via EndMT still needs to be clarified. Herein, elevated levels of Birc3 expression along with EndMT-associated alterations, including increased α-smooth muscle actin (α-SMA) levels and decreased CD31 expression, were observed in fibrotic kidneys of Unilateral Ureteral Obstruction (UUO)-induced mouse models and transforming growth factor-ß (TGF-ß)-induced EndMT in Human Umbilical Vein Endothelial Cells (HUVECs). Functionally, Birc3 knockdown inhibited EndMT and mitochondrial fission mediated by dynamin-related protein 1 (Drp1) both in vivo and in vitro. Mechanistically, endothelial Birc3 exacerbated Drp-1-induced mitochondrial fission through the MAPK/PI3K/Akt signaling pathway in endothelial cell models stimulated TGF-ß. Collectively, these findings illuminate the mechanisms and indicate that targeting Birc3 could offer a promising therapeutic strategy to improve endothelial cell survival and mitigate the progression of CKD.

Meis1 Targets Protein Tyrosine Phosphatase Receptor J in Fibroblast to Retard Chronic Kidney Disease Progression.

Renal fibrosis is a common pathological feature of chronic kidney disease (CKD) with the proliferation and activation of myofibroblasts being definite effectors and drivers. Here, increased expression of Meis1 (myeloid ecotropic viral integration site 1) is observed, predominantly in the nucleus of the kidney of CKD patients and mice, and negatively correlates with serum creatinine. Fibroblast-specific knock-in of Meis1 inhibits myofibroblast activation and attenuates renal fibrosis and kidney dysfunction in CKD models. Overexpression of Meis1 in NRK-49F cells suppresses the pro-fibrotic response induced by transforming growth factor-ß1 but accelerates by its knockdown. Mechanistically, Meis1 targets protein tyrosine phosphatase receptor J (Ptprj) to block renal fibrosis by inhibiting the proliferation and activation of fibroblasts. Finally, a new activator of Ptprj is identified through computer-aided virtual screening, which has the effect of alleviating renal fibrosis. Collectively, these results illustrate that the Meis1/Ptprj axis has therapeutic potential for clinically treating CKD.

Targeting Neuraminidase 4 Attenuates Kidney Fibrosis in Mice.

Despite significant progress in therapy, there remains a lack of substantial evidence regarding the molecular factors that lead to renal fibrosis. Neuraminidase 4 (NEU4), an enzyme that removes sialic acids from glycoconjugates, has an unclear role in chronic progressive fibrosis. Here, this study finds that NEU4 expression is markedly upregulated in mouse fibrotic kidneys induced by folic acid or unilateral ureter obstruction, and this elevation is observed in patients with renal fibrosis. NEU4 knockdown specifically in the kidney attenuates the epithelial-to-mesenchymal transition, reduces the production of pro-fibrotic cytokines, and decreases cellular senescence in male mice. Conversely, NEU4 overexpression exacerbates the progression of renal fibrosis. Mechanistically, NEU4254-388aa interacts with Yes-associated protein (YAP) at WW2 domain (231-263aa), promoting its nucleus translocation and activation of target genes, thereby contributing to renal fibrosis. 3,5,6,7,8,3',4'-Heptamethoxyflavone, a natural compound, is identified as a novel NEU4 inhibitor, effectively protecting mice from renal fibrosis in a NEU4-dependent manner. Collectively, the findings suggest that NEU4 may represent a promising therapeutic target for kidney fibrosis.

A novel role of ADAMTS16 in renal fibrosis through activating TGF-ß/Smad signaling.

Chronic Kidney Disease (CKD) has emerged as a global public health concern, with its primary pathological basis being Renal Fibrosis (RF), crucial to halt its progression to End-Stage Renal Disease (ESRD). However, effective treatment options are currently lacking. Therefore, exploring the mechanisms of RF, identifying drug targets and diagnostic biomarkers are important. In this study, we identified ADAMTS16 as a newly expressed regulatory factor highly expressed in renal fibrosis tissue. ADAMTS16 interacts with latency-associated peptide (LAP)-transforming growth factor (TGF)-ß, leading to the activation of TGF-ß. Loss of ADAMTS16 expression effectively reduces TGF-ß-dependent transcription activity. Furthermore, the use of RRFR tetrapeptide derived from ADAMTS16 can activate the TGF-ß/Smad signaling axis, promoting RF. In summary, ADAMTS16 is induced in the progression of CKD, interacting with LAP-TGF-ß and potentially activating SMAD2/3. Therefore, targeting ADAMTS16 may serve as a crucial new strategy to alleviate RF and treat CKD patients.

USP11 promotes renal tubular cell pyroptosis and fibrosis in UUO mice via inhibiting KLF4 ubiquitin degradation.

The pyroptosis of renal tubular epithelial cells leads to tubular loss and inflammation and then promotes renal fibrosis. The transcription factor Krüppel-like factor 4 (KLF4) can bidirectionally regulate the transcription of target genes. Our previous study revealed that sustained elevation of KLF4 is responsible for the transition of acute kidney injury (AKI) into chronic kidney disease (CKD) and renal fibrosis. In this study, we explored the upstream mechanisms of renal tubular epithelial cell pyroptosis from the perspective of posttranslational regulation and focused on the transcription factor KLF4. Mice were subjected to unilateral ureteral obstruction (UUO) surgery and euthanized on D7 or D14 for renal tissue harvesting. We showed that the pyroptosis of renal tubular epithelial cells mediated by both the Caspase-1/GSDMD and Caspase-3/GSDME pathways was time-dependently increased in UUO mouse kidneys. Furthermore, we found that the expression of the transcription factor KLF4 was also upregulated in a time-dependent manner in UUO mouse kidneys. Tubular epithelial cell-specific Klf4 knockout alleviated UUO-induced pyroptosis and renal fibrosis. In Ang II-treated mouse renal proximal tubular epithelial cells (MTECs), we demonstrated that KLF4 bound to the promoter regions of Caspase-3 and Caspase-1 and directly increased their transcription. In addition, we found that ubiquitin-specific protease 11 (USP11) was increased in UUO mouse kidneys. USP11 deubiquitinated KLF4. Knockout of Usp11 or pretreatment with the USP11 inhibitor mitoxantrone (3 mg/kg, i.p., twice a week for two weeks before UUO surgery) significantly alleviated the increases in KLF4 expression, pyroptosis and renal fibrosis. These results demonstrated that the increased expression of USP11 in renal tubular cells prevents the ubiquitin degradation of KLF4 and that elevated KLF4 promotes inflammation and renal fibrosis by initiating tubular cell pyroptosis.

To target cellular senescence in diabetic kidney disease: the known and the unknown.

Cellular senescence represents a condition of irreversible cell cycle arrest, characterized by heightened senescence-associated beta-galactosidase (SA-ß-Gal) activity, senescence-associated secretory phenotype (SASP), and activation of the DNA damage response (DDR). Diabetic kidney disease (DKD) is a significant contributor to end-stage renal disease (ESRD) globally, with ongoing unmet needs in terms of current treatments. The role of senescence in the pathogenesis of DKD has attracted substantial attention with evidence of premature senescence in this condition. The process of cellular senescence in DKD appears to be associated with mitochondrial redox pathways, autophagy, and endoplasmic reticulum (ER) stress. Increasing accumulation of senescent cells in the diabetic kidney not only leads to an impaired capacity for repair of renal injury, but also the secretion of pro-inflammatory and profibrotic cytokines and growth factors causing inflammation and fibrosis. Current treatments for diabetes exhibit varying degrees of renoprotection, potentially via mitigation of senescence in the diabetic kidney. Targeting senescent cell clearance through pharmaceutical interventions could emerge as a promising strategy for preventing and treating DKD. In this paper, we review the current understanding of senescence in DKD and summarize the possible therapeutic interventions relevant to senescence in this field.

Activation of SIRT3 by Tanshinone IIA ameliorates renal fibrosis by suppressing the TGF-ß/TSP-1 pathway and attenuating oxidative stress.

Although doxorubicin (DOX) is a common chemotherapeutic drug, the serious nephrotoxicity caused by DOX-induced renal fibrosis remains a considerable clinical problem. Tanshinone IIA (Tan IIA), a compound extracted from Salvia miltiorrhiza, has been reported to have an anti-fibrotic effect. Therefore, this study investigated the molecular pathway whereby Tan IIA protects the kidneys from DOX administration. DOX (3 mg/kg body weight) was intraperitoneally administered every 3 d for a total of 7 injections (cumulative dose of 21 mg/kg) to induce nephrotoxicity. Then, Tan IIA (5 or 10 mg/kg/d) was administered by intraperitoneal injection for 28 d. In an in vitro study, 293 T cells were cultured and treated with DOX and Tan IIA for 24 h. Tan IIA reduced the blood urea nitrogen levels elevated by DOX while increasing superoxide dismutase activity, down-regulating reactive oxygen species, ameliorating renal-tubule thickening, and rescuing mitochondrial morphology. Additionally, Tan IIA reduced the renal collagen deposition, increased ATP production and complex-I activity, down-regulated transforming growth factor-ß1 (TGF-ß1) and thrombospondin-1 (TSP-1), and up-regulated sirtuin 3 (SIRT3). Tan IIA significantly increased cell viability. Additionally, RNA interference was employed to silence the expression of SIRT3, which eliminated the effect of Tan IIA in suppressing the expression of TGF-ß1 and TSP-1. In conclusion, Tan IIA ameliorated DOX-induced nephrotoxicity by attenuating oxidative injury and fibrosis. The Tan IIA-induced rescue of mitochondrial morphology and function while alleviating renal fibrosis may be associated with the activation of SIRT3 to suppress the TGF-ß/TSP-1 pathway.

CD5L up-regulates the TGF-ß signaling pathway and promotes renal fibrosis.

Renal fibrosis is the common final pathway of progressive renal diseases, in which the macrophages play an important role. ELISA was used to detect CD5 antigen-like (CD5L) in serum samples from end-stage renal disease (ESRD), as well as in mice serum with unilateral ureteral occlusion (UUO). Recombinant CD5L was injected into UUO mice to assess renal injury, fibrosis, and macrophage infiltration. The expression of CD5L was significantly upregulated in the serum of patients with ESRD and UUO mice. Histological analysis showed that rCD5L-treated UUO mice had more severe renal injury and fibrosis. Furthermore, rCD5L promoted the phenotypic transfer of monocytes from Ly6Chigh to LyC6low. RCD5L promoted TGF-ß signaling pathway activation by promoting Smad2/3 phosphorylation. We used Co-IP to identify HSPA5 interact with CD5L on cell membrane could inhibit the formation of the Cripto/HSPA5 complex, and promote the activation of the TGF-ß signaling pathway. The CD5L antibody could reduce the degree of renal fibrosis in UUO mice.