Renal tubulointerstitial fibrosis: common but never simple

Crosstalk between proximal tubular epithelial cells and other interstitial cells in tubulointerstitial fibrosis after renal injury

The energy needs of tubular epithelial components, especially proximal tubular epithelial cells (PTECs), are high and they heavily depend on aerobic metabolism. As a result, they are particularly vulnerable to various injuries caused by factors such as ischemia, proteinuria, toxins, and elevated glucose levels. Initial metabolic and phenotypic changes in PTECs after injury are likely an attempt at survival and repair. Nevertheless, in cases of recurrent or prolonged injury, PTECs have the potential to undergo a transition to a secretory state, leading to the generation and discharge of diverse bioactive substances, including transforming growth factor-β, Wnt ligands, hepatocyte growth factor, interleukin (IL)-1β, lactic acid, exosomes, and extracellular vesicles. By promoting fibroblast activation, macrophage recruitment, and endothelial cell loss, these bioactive compounds stimulate communication between epithelial cells and other interstitial cells, ultimately worsening renal damage. This review provides a summary of the latest findings on bioactive compounds that facilitate the communication between these cellular categories, ultimately leading to the advancement of tubulointerstitial fibrosis (TIF).

Artificial intelligence-assisted repurposing of lubiprostone alleviates tubulointerstitial fibrosis

Tubulointerstitial fibrosis (TIF) is the most prominent cause which leads to chronic kidney disease (CKD) and end-stage renal failure. Despite extensive research, there have been many clinical trial failures, and there is currently no effective treatment to cure renal fibrosis. This demonstrates the necessity of more effective therapies and better preclinical models to screen potential drugs for TIF. In this study, we investigated the antifibrotic effect of the machine learning-based repurposed drug, lubiprostone, validated through an advanced proximal tubule on a chip system and in vivo UUO mice model. Lubiprostone significantly downregulated TIF biomarkers including connective tissue growth factor (CTGF), extracellular matrix deposition (Fibronectin and collagen), transforming growth factor (TGF-β) downstream signaling markers especially, Smad-2/3, matrix metalloproteinase (MMP2/9), plasminogen activator inhibitor-1 (PAI-1), EMT and JAK/STAT-3 pathway expression in the proximal tubule on a chip model and UUO model compared to the conventional 2D culture. These findings suggest that the proximal tubule on a chip model is a more physiologically relevant model for studying and identifying potential biomarkers for fibrosis compared to conventional in vitro 2D culture and alternative of an animal model. In conclusion, the high throughput Proximal tubule-on-chip system shows improved in vivo-like function and indicates the potential utility for renal fibrosis drug screening. Additionally, repurposed Lubiprostone shows an effective potency to treat TIF via inhibiting 3 major profibrotic signaling pathways such as TGFβ/Smad, JAK/STAT, and epithelial-mesenchymal transition (EMT), and restores kidney function.

Dioscorea nipponica Makino: A comprehensive review of its chemical composition and pharmacology on chronic kidney disease

Chronic kidney disease (CKD) is a widespread ailment that significantly impacts global health. It is characterized by high prevalence, poor prognosis, and substantial healthcare costs, making it a major public health concern. The current clinical treatments for CKD are not entirely satisfactory, leading to a high demand for alternative therapeutic options. Chinese herbal medicine, with its long history, diverse varieties, and proven efficacy, offers a promising avenue for exploration. One such Chinese herbal medicine, Dioscorea nipponica Makino (DNM), is frequently used to treat kidney diseases. In this review, we have compiled studies examining the mechanisms of action of DNM in the context of CKD, focusing on five primary areas: improvement of oxidative stress, inhibition of renal fibrosis, regulation of metabolism, reduction of inflammatory response, and regulation of autophagy.

Single cell G-protein coupled receptor profiling of activated kidney fibroblasts expressing transcription factor 21

BACKGROUND AND PURPOSE

Activated fibroblasts deposit fibrotic matrix in chronic kidney disease (CKD) and G-protein coupled receptors (GPCRs) are the most druggable therapeutic targets. Here, we set out to establish a transcriptional profile that identifies activated kidney fibroblasts and the GPCRs that they express.

EXPERIMENTAL APPROACH

RNA sequencing and single cell qRT-PCR were performed on mouse kidneys after unilateral ureteral obstruction (UUO). Candidate expression was evaluated in mice with UUO or diabetes or injected with adriamycin or folic acid. Intervention studies were conducted in mice with diabetes or UUO. Correlative histology was performed in human kidney tissue.

KEY RESULTS

Transcription factor 21 (Tcf21)+ cells that expressed 2 or 3 of Postn, Acta2 and Pdgfra were highly enriched for fibrogenic genes and were defined as activated kidney fibroblasts. Tcf21+ α-smooth muscle actin (α-SMA)+ interstitial cells accumulated in kidneys of mice with UUO or diabetes or injected with adriamycin or folic acid, whereas renin-angiotensin system blockade attenuated increases in Tcf21 in diabetic mice. Fifty-six GPCRs were up-regulated in single Tcf21+ kidney fibroblasts, the most up-regulated being Adgra2 and S1pr3. Adenosine receptors, Adora2a/2b, were up-regulated in Tcf21+ fibroblasts and the adenosine receptor antagonist, caffeine decreased Tcf21 upregulation and kidney fibrosis in UUO mice. TCF21, ADGRA2, S1PR3 and ADORA2A/2B were each detectable in α-SMA+ interstitial cells in human kidney samples.

CONCLUSION AND IMPLICATIONS

Tcf21 is a marker of kidney fibroblasts that are enriched for fibrogenic genes in CKD. Further analysis of the GPCRs expressed by these cells may identify new targets for treating CKD.

LINKED ARTICLES

This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

A sub-10-nm, folic acid-conjugated gold nanoparticle as self-therapeutic treatment of tubulointerstitial fibrosis

Nanomedicines for treating chronic kidney disease (CKD) are on the horizon, yet their delivery to renal tubules where tubulointerstitial fibrosis occurs remains inefficient. We report a folic acid-conjugated gold nanoparticle that can transport into renal tubules and treat tubulointerstitial fibrosis in mice with unilateral ureteral obstruction. The 3-nm gold core allows for the dissection of bio-nano interactions in the fibrotic kidney, ensures the overall nanoparticle (~7 nm) to be small enough for glomerular filtration, and naturally inhibits the p38α mitogen-activated protein kinase in the absence of chemical or biological drugs. The folic acids support binding to selected tubule cells with overexpression of folate receptors and promote retention in the fibrotic kidney. Upon intravenous injection, this nanoparticle can selectively accumulate in the fibrotic kidney over the nonfibrotic contralateral kidney at ~3.6% of the injected dose. Delivery to the fibrotic kidney depends on nanoparticle size and disease stage. Notably, a single injection of this self-therapeutic nanoparticle reduces tissue degeneration, inhibits genes related to the extracellular matrix, and treats fibrosis more effectively than standard Captopril therapy. Our data underscore the importance of constructing CKD nanomedicines based on renal pathophysiology.

Using Ultrahigh b -Value Diffusion-Weighted Imaging to Noninvasively Assess Renal Fibrosis in a Rabbit Model of Renal Artery Stenosis

OBJECTIVE

This study aimed to investigate the feasibility of diffusion-weighted imaging with ultrahigh b values ( ub DWI) for the evaluation of renal fibrosis (RF) induced by renal artery stenosis (RAS) in a rabbit model.

METHODS

Thirty-two rabbits underwent left RAS operation, whereas 8 rabbits received sham surgery. All rabbits underwent ub DWI ( b = 0-4500 s/mm 2 ). The standard apparent diffusion coefficient (ADC st ), molecular diffusion coefficient ( D ), perfusion fraction ( f ), perfusion-related diffusion coefficient ( D *) and ultrahigh apparent diffusion coefficient (ADC uh ) were longitudinally assessed before operation and at weeks 2, 4, and 6 after operation. The degree of interstitial fibrosis and the expression of aquaporin (AQP) 1 and AQP2 were determined through pathological examination.

RESULTS

In the stenotic kidney, the ADC st , D , f , and ADC uh values of the renal parenchyma significantly decreased compared with those at baseline (all P < 0.05), whereas the D * values significantly increased after RAS induction ( P < 0.05). The ADC st , D , D *, and f were weakly to moderately correlated with interstitial fibrosis as well as with the expression of AQP1 and AQP2. Furthermore, the ADC uh negatively correlated with interstitial fibrosis ( ρ = -0.782, P < 0.001) and positively correlated with AQP1 and AQP2 expression ( ρ = 0.794, P < 0.001, and ρ = 0.789, P < 0.001, respectively).

CONCLUSIONS

Diffusion-weighted imaging with ultrahigh b values shows the potential for noninvasive assessment of the progression of RF in rabbits with unilateral RAS. The ADC uh derived from ub DWI could reflect the expression of AQPs in RF.

Astragaloside IV Blunts Epithelial-Mesenchymal Transition and G2/M Arrest to Alleviate Renal Fibrosis via Regulating ALDH2-Mediated Autophagy

Previous studies show that astragaloside IV (ASIV) has anti-renal fibrosis effects. However, its mechanism remains elusive. In this study, we investigated the anti-fibrosis mechanisms of ASIV on chronic kidney disease (CKD) in vivo and in vitro. A CKD model was induced in rats with adenine (200 mg/kg/d, i.g.), and an in vitro renal fibrosis model was induced in human kidney-2 (HK-2) cells treated with TGF-β1. We revealed that ASIV significantly alleviated renal fibrosis by suppressing the expressions of epithelial-mesenchymal transition (EMT)-related proteins, including fibronectin, vimentin, and alpha-smooth muscle actin (α-SMA), and G2/M arrest-related proteins, including phosphorylated p53 (p-p53), p21, phosphorylated histone H3 (p-H3), and Ki67 in both of the in vivo and in vitro models. Transcriptomic analysis and subsequent validation showed that ASIV rescued ALDH2 expression and inhibited AKT/mTOR-mediated autophagy. Furthermore, in ALDH2-knockdown HK-2 cells, ASIV failed to inhibit AKT/mTOR-mediated autophagy and could not blunt EMT and G2/M arrest. In addition, we further demonstrated that rapamycin, an autophagy inducer, reversed the treatment of ASIV by promoting autophagy in TGF-β1-treated HK-2 cells. A dual-luciferase report assay indicated that ASIV enhanced the transcriptional activity of the ALDH2 promoter. In addition, a further molecular docking analysis showed the potential interaction of ALDH2 and ASIV. Collectively, our data indicate that ALDH2-mediated autophagy may be a novel target in treating renal fibrosis in CKD models, and ASIV may be an effective targeted drug for ALDH2, which illuminate a new insight into the treatment of renal fibrosis and provide new evidence of pharmacology to elucidate the anti-fibrosis mechanism of ASIV in treating renal fibrosis.

Routes of Albumin Overload Toxicity in Renal Tubular Epithelial Cells

Besides being a marker of kidney disease severity, albuminuria exerts a toxic effect on renal proximal tubular epithelial cells (RPTECs). We evaluated whether an unfolded protein response (UPR) or DNA damage response (DDR) is elicited in RPTECs exposed to high albumin concentration. The deleterious outcomes of the above pathways, apoptosis, senescence, or epithelial-to-mesenchymal transition (EMT) were evaluated. Albumin caused reactive oxygen species (ROS) overproduction and protein modification, and a UPR assessed the level of crucial molecules involved in this pathway. ROS also induced a DDR evaluated by critical molecules involved in this pathway. Apoptosis ensued through the extrinsic pathway. Senescence also occurred, and the RPTECs acquired a senescence-associated secretory phenotype since they overproduced IL-1β and TGF-β1. The latter may contribute to the observed EMT. Agents against endoplasmic reticulum stress (ERS) only partially alleviated the above changes, while the inhibition of ROS upregulation prevented both UPR and DDR and all the subsequent harmful effects. Briefly, albumin overload causes cellular apoptosis, senescence, and EMT in RPTECs by triggering UPR and DDR. Promising anti-ERS factors are beneficial but cannot eliminate the albumin-induced deleterious effects because DDR also occurs. Factors that suppress ROS overproduction may be more effective since they could halt UPR and DDR.

Folic Acid Ameliorates Renal Injury in Experimental Obstructive Nephropathy: Role of Glycine N-Methyltransferase

Folic acid exerts both anti-inflammatory and antifibrotic effects. Glycine N-methyltransferase (GNMT), the major folic acid-binding protein in the liver, is a crucial enzyme that regulates the cellular methylation process by maintaining S-adenosylmethionine levels. However, as yet neither the therapeutic effects of folic acid in renal fibrosis nor whether GNMT is involved in these folic acid-associated mechanisms has been investigated. First, the expression of GNMT was examined in human kidneys with or without obstructive nephropathy. Later, wild-type and GNMT knockout (GNMT^-/-) mice were subjected to unilateral ureteral obstruction (UUO) and then treated with either folic acid or vehicle for 14 days. Renal tubular injury, inflammation, fibrosis, and autophagy were evaluated by histological analysis and Western blotting. We observed increased expression of GNMT in humans with obstructive nephropathy. Furthermore, UUO significantly increased the expression of GNMT in mice; in addition, it caused renal injury as well as the development of both hydronephrosis and tubular injury. These were all alleviated by folic acid treatment. In contrast, GNMT^-/- mice exhibited exacerbated UUO-induced renal injury, but the protective effect of folic acid was not observed in GNMT^-/- mice. We propose a novel role for folic acid in the treatment of renal fibrosis, which indicates that GNMT may be a therapeutic target.

CDC20 inhibition alleviates fibrotic response of renal tubular epithelial cells and fibroblasts by regulating nuclear translocation of β-catenin

Fibrosis is a common pathological phenomenon in progressive kidney disease leading to eventual loss of kidney function. Previous studies demonstrated that CDC20 plays a role in cancers by regulating epithelial-mesenchymal transition (EMT) and the infiltration of fibroblasts, suggesting the potential of CDC20 in regulating fibrotic response. However, the role of CDC20 in renal fibrosis is yet unclear. Herein, we reported that renal CDC20 was remarkably upregulated in renal tubular epithelial cells and fibroblasts in chronic kidney disease (CKD) patients, which was in line with a positive correlation with the severity of kidney fibrosis. In mice with unilateral urinary obstruction, CDC20 was also strikingly enhanced, and treatment with Apcin, an inhibitor of CDC20, ameliorated kidney fibrosis. Consistently, the pharmacological inhibition of CDC20 in mouse proximal tubular epithelial cells and rat fibroblasts attenuated TGF-β1-induced fibrotic responses, while overexpression of CDC20 aggravated such responses. Additional studies revealed that CDC20 induces nuclear translocation of β-catenin, which in turn initiates and promotes the pathological process of fibrosis in CKD. Thus, enhanced CDC20 in renal tubular cells and fibroblasts promotes renal fibrosis by activating β-catenin, and CDC20 inhibition may serve as a promising strategy for the prevention and treatment of renal fibrosis.

[Towards understanding chronic kidney disease]

Chronic kidney disease (CKD) is a global health problem affecting almost 15% of the population worldwide. After renal injury, there is a nephron loss and remaining nephrons ensure the glomerular filtration rate (GFR) with compensatory hyperplasia and hypertrophy: This is called the nephron reduction. After nephron reduction, renal function will gradually decline and lead to chronic end-stage renal failure. Whatever the initial cause of the renal injury, recent data suggest there are common molecular mechanisms at the origin of CKD progression. Moreover, the renal lesions are very reproducible with glomerulosclerosis, tubular atrophy and partial epithelio-mesenchymal transition, interstitial fibrosis and vascular abnormalities. The physiopathology of CKD progression is unclear but some hypotheses have been described: i) the nephron "overwork", supported by recent works showing that the nephron reduction leads to hyperfiltration by the remaining nephrons and the stability of the GFR; ii) the "podocyte adaptation" theory, reflected by the importance of the podocytopathy in CKD progression and the crucial role of residual proteinuria in renal lesion development; iii) the activation of EGFR signaling pathways in surgical nephron reduction model and its involvement in CKD progression. Finally, CKD progression remains poorly understood and further studies will be necessary to discover new CKD molecular pathways and to develop new therapeutic insight in CKD management.

Fibrosis imaging with multiparametric proton and sodium MRI in pig injury models

Chronic kidney disease (CKD) is common and has huge implications for health and mortality. It is aggravated by intrarenal fibrosis, but the assessment of fibrosis is limited to kidney biopsies, which carry a risk of complications and sampling errors. This calls for a noninvasive modality for diagnosing and staging intrarenal fibrosis. The current, exploratory study evaluates a multiparametric MRI protocol including sodium imaging (²³ Na-MRI) to determine the opportunities within this modality to assess kidney injury as a surrogate endpoint of fibrosis. The study includes 43 pigs exposed to ischemia-reperfusion injury (IRI) or unilateral ureteral obstruction (UUO), or serving as healthy controls. Fibrosis was determined using gene expression analysis of collagen. The medulla/cortex ratio of ²³ Na-MRI decreased in the injured kidney in the IRI pigs, but not in the UUO pigs (p = 0.0180, p = 0.0754). To assess the combination of MRI parameters in estimating fibrosis, we created a linear regression model consisting of the cortical apparent diffusion coefficient, ΔR2*, ΔT1, the ²³ Na medulla/cortex ratio, and plasma creatinine (R²  = 0.8009, p = 0.0117). The ²³ Na medulla/cortex ratio only slightly improved the fibrosis prediction model, leaving ²³ Na-MRI in an ambiguous place for evaluation of intrarenal fibrosis. Use of multiparametric MRI in combination with plasma creatinine shows potential for the estimation of fibrosis in human kidney disease, but more translational and clinical work is warranted before MRI can contribute to earlier diagnosis and evaluation of treatment for acute kidney injury and CKD.

Noninvasive assessment of renal function and fibrosis in CKD patients using histogram analysis based on diffusion kurtosis imaging

PURPOSE

To investigate the potential of histogram analysis based on diffusion kurtosis imaging (DKI) in evaluating renal function and fibrosis associated with chronic kidney disease (CKD).

MATERIALS AND METHODS

Thirty-six CKD patients were enrolled, and DKI was performed in all patients before the renal biopsy. The histogram parameters of diffusivity (D) and kurtosis (K) were obtained using FireVoxel. The histogram parameters between the stable [estimated glomerular filtration rate (eGFR) ≥ 60 ml/min/1.73 m²] and impaired (eGFR < 60 ml/min/1.73 m²) eGFR group were compared. Besides, patients were classified into mild, moderate, and severe fibrosis group using a semi-quantitative standard. The correlations of histogram parameters with eGFR and fibrosis scores were investigated and the diagnostic performances of histogram parameters in assessing renal dysfunction and fibrosis were analyzed. The added value of combination of most significant parameter with 24 h urinary protein (24 h-UPRO) in evaluating fibrosis was also explored.

RESULTS

Seven D histogram parameters in cortex (mean, median, 10th, 25th, 75th, 90th percentiles and entropy), two D histogram parameters in medulla (75th, 90th percentiles), seven K histogram parameters in cortex (mean, min, median, 10th, 25th, 75th, 90th percentiles) and three K histogram parameters in medulla (mean, median, 25th percentile) were significantly different between the two groups. The D_mean of cortex was the most relevant parameter to eGFR (r = 0.648, P < 0.001) and had the largest area under the curve (AUC) for differentiating the stable from impaired eGFR group [AUC = 0.889; 95% confidence interval (CI) 0.728-0.970]. The K_90th of cortex presented the strongest correlation with fibrosis scores (r = 0.575, P < 0.001) and achieved the largest AUC for distinguishing the mild from moderate to severe fibrosis group (AUC = 0.849, 95% CI 0.706-0.993). Combining the K_90th in cortex with 24 h-UPRO gained statistically higher AUC value (AUC = 0.880, 95% CI 0.763-0.996).

CONCLUSION

Histogram analysis based on DKI is practicable for the noninvasive assessment of renal function and fibrosis in CKD patients.

Development of Cell Therapies for Renal Disease and Regenerative Medicine

The incidence of renal disease is gradually increasing worldwide, and this condition has become a major public health problem because it is a trigger for many other chronic diseases. Cell therapies using multipotent mesenchymal stromal cells, hematopoietic stem cells, macrophages, and other cell types have been used to induce regeneration and provide a cure for acute and chronic kidney disease in experimental models. This review describes the advances in cell therapy protocols applied to acute and chronic kidney injuries and the attempts to apply these treatments in a clinical setting.

Type XXVIII Collagen Regulates Renal Interstitial Fibrosis and Epithelial-Mesenchymal Transition by SREBP1-Mediated HKDC1 Expression

Background. A novel collagen called type XXVIII collagen (COL28) is involved in cancer and lung fibrosis. Preliminary data showed that renal tubular epithelial cells could proliferate, migrate, and undergo an epithelial-mesenchymal transition (EMT) when COL28 was overexpressed; however, it is still unknown how this occurs and what the underlying mechanism is. Methods. We analyzed the differential expression of genes (DEGs) in the stable COL28 overexpression HK-2 cell lines by RNA-sequencing analysis, before which Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes (KEGG) analyses were performed. Genes related to COL28 promoting HK-2 cell proliferation and EMT were screened and verified. By using western blot and immunofluorescence, the effects of COL28 on the expression of α-SMA, E-cadherin, Snail, HKDC1, and SREBP1 were detected. The effect of COL28 overexpression on renal fibrosis in unilateral ureteral obstruction (UUO) mice was detected by H&E and Masson staining. HKDC1 interference agent was synthesized and transfected into the HK-2 cell line stably overexpressing COL28. In HK-2 cells, the effects of HKDC1 interference on the expression of α-SMA, E-cadherin, and Snail were detected. Results. We screened and verified that HKDC1 was related to COL28 and promoted HK-2 cell proliferation and EMT. WB showed that in HK-2 cells, COL28 overexpression increased α-SMA, Snail, HKDC1, and SREBP1 expressions and decreased E-cadherin expression. Overexpression of COL28 aggravated renal interstitial fibrosis in UUO mice; upregulated α-SMA, Snail, HKDC1, and SREBP1 expressions; and decreased the E-cadherin protein expression in UUO mice. Interference of HKDC1 expression promoted the E-cadherin protein expression while inhibiting α-SMA, Snail, HKDC1, and SREBP1 protein expressions. Conclusion. Overexpression of COL28 can aggravate renal interstitial fibrosis by encouraging renal tubular epithelial cells to undergo EMT, and interference with HKDC1 expression can alleviate fibrosis by reversing EMT induced by COL28 overexpression.

The atypical sphingosine 1-phosphate variant, d16:1 S1P, mediates CTGF induction via S1P2 activation in renal cell carcinoma

Sphingosine 1-phosphate (S1P) is a lipid mediator with numerous biological functions. The term 'S1P' mainly refers to the sphingolipid molecule with a long-chain sphingoid base of 18 carbon atoms, d18:1 S1P. The enzyme serine palmitoyltransferase catalyses the first step of the sphingolipid de novo synthesis using palmitoyl-CoA as the main substrate. After further reaction steps, d18:1 S1P is generated. However, also stearyl-CoA or myristoyl-CoA can be utilised by the serine palmitoyltransferase, which at the end of the S1P synthesis pathway, results in the production of d20:1 S1P and d16:1 S1P respectively. We measured these S1P homologues in mice and renal tissue of patients suffering from renal cell carcinoma (RCC). Our experiments highlight the relevance of d16:1 S1P for the induction of connective tissue growth factor (CTGF) in the human renal clear cell carcinoma cell line A498 and human RCC tissue. We show that d16:1 S1P versus d18:1 and d20:1 S1P leads to the highest CTGF induction in A498 cells via S1P2 signalling and that both d16:1 S1P and CTGF levels are elevated in RCC compared to adjacent healthy tissue. Our data indicate that d16:1 S1P modulates conventional S1P signalling by acting as a more potent agonist at the S1P2 receptor than d18:1 S1P. We suggest that elevated plasma levels of d16:1 S1P might play a pro-carcinogenic role in the development of RCC via CTGF induction.

Autophagy-induced mesenchymal stem cell-derived extracellular vesicles ameliorated renal fibrosis in an in vitro model

Introduction

Chronic and progressive damage to the kidney by inflammatory processes, may lead to an increase in the extracellular matrix production, a condition known as renal fibrosis. The current study aims to evaluate if the extracellular vesicles (EVs) derived from autophagic adipose-derived mesenchymal stem cells (ADMSCs) can reduce the inflammation and extracellular matrix accumulation in damaged kidney tissue.

Methods

Autophagy was induced in ADMSCs using 2µM concentration curcumin and was confirmed by evaluating LC3B, ATG7, and Beclin1 using real-time polymerase chain reaction (PCR) and Western blot. An in vitro renal fibrotic model was established in HEK-293 cells exposed to H2O2 (0.8mM) for 24 and 72 hours. The fibrotic model was confirmed through evaluation of collagen I, transforming growth factor-beta 1 (TGF-β1), E-cadherin, and vimentin genes expression using real-time PCR, collagen I protein by ELISA. After induction of fibrosis for 24 and 72 hours, the HEK cells were treated with NEVs (non-autophagy EVs) (50µM) or AEVs (autophagy EVs) (50µM) at 48, 96, and 124 hours, and then the samples were collected at 72 and 148 hours. Expression of collagen I, TGF-β1, E-cadherin, and vimentin Genes was evaluated via RT-PCR, and protein levels of IL1, TNF-α, IL4, IL10 using ELISA.

Results

Induction of autophagy using curcumin (2µM) for 24 hours significantly increased LC3B, Beclin1, and ATG7 in the ADMSCs. Upregulation in anti-fibrotic (E-cadherin) and anti-inflammatory (IL4, IL10) gene expression was significantly different in the fibrotic model treated by AEVs compared to NEVs. Also, the downregulation of fibrotic (TGF-β1, vimentin, collagen I) and pro-inflammatory (IL1, TNFα) gene expression was significantly different in AEVs compared with those treated by NEVs.

Conclusion

Our findings suggest that AEVs can be considered as a therapeutic modality for renal fibrosis in the future.

The significance of fibroblast growth factor-2 and kidney injury molecule-1 as biomarker of interstitial renal fibrosis in glomerulonephritis

Background

Renal tubulointerstitial fibrosis is a structural marker and prominent pathological characteristic of chronic progressive kidney disease, fibroblast growth factor-2 (FGF2) is a key fibrogenic cytokine that is likely to be involved in the pathogenesis of renal fibrosis, kidney injury molecule-1 (KIM-1) is one of the most promising, early biomarkers of renal disease, either acute or chronic, due to its translatability between preclinical and clinical trials. It is believed that this molecule participates in the process of both kidney injury and healing.

Methods

We prospectively enrolled a cohort study of eighty adult patients who had glomerular diseases (with glomerular filtration rate (GFR) > 30 ml/min/m2); serum level of FGF-2 and KIM-1 was measured at the same time of renal biopsy and was correlated with the degree of interstitial renal fibrosis.

Results

We found a significant positive correlation between FGF-2 and KIM-1 and the degree of interstitial renal fibrosis, albumin, and creatinine (P≤ 0.001), and a negative significant correlation with GFR and proteinuria. there is a positive significant correlation between serum KIM-1 and FGF-2 and hypertension with a significant P value (<0.001) that serum KIM-1 has sensitivity 90% and specificity of 95% and serum FGF-2 has sensitivity 95% and specificity 95% for detection of interstitial renal fibrosis.

Conclusions

Serum FGF-2 and KIM-1 seem to be a non-invasive novel biomarker of interstitial renal fibrosis in glomerulonephritis patients. It may become a useful biomarker without the need for the invasive maneuver of the renal biopsy. FGF-2 and KIM-1 are expected to be therapeutic targets for kidney injury.

Chemokine CCL9 Is Upregulated Early in Chronic Kidney Disease and Counteracts Kidney Inflammation and Fibrosis

Inflammation and fibrosis play an important pathophysiological role in chronic kidney disease (CKD), with pro-inflammatory mediators and leukocytes promoting organ damage with subsequent fibrosis. Since chemokines are the main regulators of leukocyte chemotaxis and tissue inflammation, we performed systemic chemokine profiling in early CKD in mice. This revealed (C-C motif) ligands 6 and 9 (CCL6 and CCL9) as the most upregulated chemokines, with significantly higher levels of both chemokines in blood (CCL6: 3–4 fold; CCL9: 3–5 fold) as well as kidney as confirmed by Enzyme-linked Immunosorbent Assay (ELISA) in two additional CKD models. Chemokine treatment in a mouse model of early adenine-induced CKD almost completely abolished the CKD-induced infiltration of macrophages and myeloid cells in the kidney without impact on circulating leukocyte numbers. The other way around, especially CCL9-blockade aggravated monocyte and macrophage accumulation in kidney during CKD development, without impact on the ratio of M1-to-M2 macrophages. In parallel, CCL9-blockade raised serum creatinine and urea levels as readouts of kidney dysfunction. It also exacerbated CKD-induced expression of collagen (3.2-fold) and the pro-inflammatory chemokines CCL2 (1.8-fold) and CCL3 (2.1-fold) in kidney. Altogether, this study reveals for the first time that chemokines CCL6 and CCL9 are upregulated early in experimental CKD, with CCL9-blockade during CKD initiation enhancing kidney inflammation and fibrosis.

Interleukin-33/ Suppression of Tumorigenicity 2 in Renal Fibrosis: Emerging Roles in Prognosis and Treatment

Chronic kidney disease (CKD) is a major public health problem that affects more than 10% of the population worldwide and has a high mortality rate. Therefore, it is necessary to identify novel treatment strategies for CKD. Incidentally, renal fibrosis plays a central role in the progression of CKD to end-stage renal disease (ESRD). The activation of inflammatory pathways leads to the development of renal fibrosis. In fact, interleukin-33 (IL-33), a newly discovered member of the interleukin 1 (IL-1) cytokine family, is a crucial regulator of the inflammatory process. It exerts pro-inflammatory and pro-fibrotic effects via the suppression of tumorigenicity 2 (ST2) receptor, which, in turn, activates other inflammatory pathways. Although the role of this pathway in cardiac, pulmonary, and hepatic fibrotic diseases has been extensively studied, its precise role in renal fibrosis has not yet been completely elucidated. Recent studies have shown that a sustained activation of IL-33/ST2 pathway promotes the development of renal fibrosis. However, with prolonged research in this field, it is expected that the IL-33/ST2 pathway will be used as a diagnostic and prognostic tool for renal diseases. In addition, the IL-33/ST2 pathway seems to be a new target for the future treatment of CKD. Here, we review the mechanisms and potential applications of the IL-33/ST2 pathway in renal fibrosis; such that it can help clinicians and researchers to explore effective treatment options and develop novel medicines for CKD patients.

Cell Cycle Dysregulation and Renal Fibrosis

Precise regulation of cell cycle is essential for tissue homeostasis and development, while cell cycle dysregulation is associated with many human diseases including renal fibrosis, a common process of various chronic kidney diseases progressing to end-stage renal disease. Under normal physiological conditions, most of the renal cells are post-mitotic quiescent cells arrested in the G0 phase of cell cycle and renal cells turnover is very low. Injuries induced by toxins, hypoxia, and metabolic disorders can stimulate renal cells to enter the cell cycle, which is essential for kidney regeneration and renal function restoration. However, more severe or repeated injuries will lead to maladaptive repair, manifesting as cell cycle arrest or overproliferation of renal cells, both of which are closely related to renal fibrosis. Thus, cell cycle dysregulation of renal cells is a potential therapeutic target for the treatment of renal fibrosis. In this review, we focus on cell cycle regulation of renal cells in healthy and diseased kidney, discussing the role of cell cycle dysregulation of renal cells in renal fibrosis. Better understanding of the function of cell cycle dysregulation in renal fibrosis is essential for the development of therapeutics to halt renal fibrosis progression or promote regression.

Attenuation of Circulating Trimethylamine N-Oxide Prevents the Progression of Cardiac and Renal Dysfunction in a Rat Model of Chronic Cardiorenal Syndrome

Chronic heart failure (HF) frequently causes progressive decline in kidney function, known as cardiorenal syndrome-2 (CRS2). Current treatment options for CRS2 remain unacceptably limited. Trimethylamine-N-oxide (TMAO), a metabolite of gut microbiota, has recently been implicated in the pathogenesis of both HF and chronic kidney disease. Here we examined whether circulating TMAO is elevated in CRS2 and if so, whether attenuation of circulating TMAO would ameliorate the progression of CRS2. Sprague-Dawley rats underwent surgery for myocardial infarction (MI) or sham (week 0) followed by subtotal (5/6) nephrectomy (STNx) or sham at week 4 to induce CRS2 or control. At week 6, MI + STNx rats and control rats received vehicle or 1.0% 3,3-Dimethyl-1-butanol (DMB, a TMAO inhibitor) treatment for 8 weeks. Compared with control rats, MI + STNx rats exhibited elevated serum TMAO at week 6, which was increased further at week 14 but was attenuated by DMB treatment. MI + STNx rats showed cardiac dysfunction as assessed by echocardiography and renal dysfunction as evidenced by increased serum creatinine and urinary kidney injury molecule-1 and decreased creatinine clearance at week 6. The cardiac and renal dysfunction in MI + STNx rats was exacerbated at week 14 but was prevented by DMB treatment. Molecular and histological studies revealed myocyte hypertrophy and increases in interstitial myocardial fibrosis and gene expression of pro-hypertrophic and pro-fibrotic markers in both heart and kidney at week 14, which were accompanied by elevated gene expression of proinflammatory cytokines. The changes in molecular and histological parameters observed in MI + STNx rats were significantly reduced by DMB treatment. These findings suggest that rats with CRS2 have elevated circulating TMAO, which is associated with the exacerbation of cardiac and renal dysfunction. Attenuation of circulating TMAO can ameliorate cardiac and renal injury and prevents the progression of CRS2.

Impact of high salt diets on CHOP-mediated apoptosis and renal fibrosis in a rat model

BACKGROUND

Prolonged and excessive salt intake accelerates oxidative stress in kidney tissues, which brings about ER stress. The PERK/ATF4/CHOP/BCL-2 signaling pathway has an essential role in ER stress-induced apoptosis. The present study aimed to investigate the effect of high salt diets on the development of renal fibrosis through CHOP-mediated apoptosis.

METHODS AND RESULTS

Twenty-five male Wistar rats were randomly divided into five groups (n = 5 each). Groups 1-5 were treated with 0%, 0.5%, 1%, 1.2%, 1.5% of NaCl dissolved in distilled water, respectively, for 8 weeks. To detect the degree of renal tubular damage, urinary KIM-1 was measured. The slides of renal tissues were stained via Masson's Trichrome staining methods for fibrosis detection. The relative gene expression of ATF4, CHOP, and BCl-2 in renal tissues were analyzed using the qRT-PCR method. The results revealed no significant difference between the urea, creatinine, and urine flow rate of the rats receiving different concentrations of NaCl (groups 2-5) and those of the control group (group 1). The rats treated with 1.5% NaCl (group 5) showed significant elevations in urinary KIM-1 and the mRNA level of CHOP compared to the control group. Mild renal fibrosis was also observed in group 5.

CONCLUSIONS

Excessive salt intake leads to fibrosis as it induces the PERK/ATF4/CHOP/BCL-2 signaling pathway in renal tissues. KIM-1 is detectable in urine before the impairment of renal function which can be used as a diagnostic marker to prevent the development of progressive renal failure.

Assessment of renal fibrosis and anti-fibrotic agents using a novel diagnostic and stain-free second-harmonic generation platform

Current histological measurement techniques for interstitial collagen, the basis of interstitial fibrosis, are semi-quantitative at best and only provide a ratio of collagen levels within tissues. The Genesis200 imaging system and supplemental image analysis software, FibroIndex from HistoIndex, is a novel, automated platform that uses second-harmonic generation (SHG) for imaging and characterization of interstitial collagen deposition and additional characteristics, in the absence of any staining. However, its ability to quantify renal fibrosis requires investigation. This study compared SHG imaging of renal fibrosis in mice with unilateral ureteric obstruction (UUO), to that of Masson's trichrome staining (MTS) and immunohistochemistry (IHC) of collagen I. Additionally, the platform generated data on collagen morphology and distribution patterns. While all three methods determined that UUO-injured mice underwent significantly increased renal fibrosis after 7 days, the HistoIndex platform additionally determined that UUO-injured mice had a significantly increased collagen-to-tissue cross reticulation ratio (all P < .001 vs sham group). Furthermore, in UUO-injured mice treated with the relaxin family peptide receptor-1 agonists, relaxin (0.5 mg/kg/day) or B7-33 (0.25 mg/kg/day), or angiotensin converting enzyme-inhibitor, perindopril (1 mg/kg/day) over the 7-day period, only the HistoIndex platform determined that the drug-induced prevention of renal fibrosis correlated with significantly reduced collagen fiber thickness and collagen-to-tissue cross reticulation ratio, but increased collagen fiber counts. Relaxin or B7-33 treatment also increased renal matrix metalloproteinase-2 and reduced tissue inhibitor of metalloproteinase-1 levels (all P < .01 vs UUO alone). This study demonstrated the diagnostic value of the HistoIndex platform over currently used staining techniques.

Chronic Kidney Disease Induced by Cisplatin, Folic Acid and Renal Ischemia Reperfusion Induces Anemia and Promotes GATA-2 Activation in Mice

Anemia is a common feature of chronic kidney disease (CKD). It is a process related to erythropoietin deficiency, shortened erythrocyte survival, uremic erythropoiesis inhibitors, and disordered iron homeostasis. Animal models of CKD-induced anemia are missing and would be desirable in order to study anemia mechanisms and facilitate the development of novel therapeutic tools. We induced three different models of CKD in mice and evaluated the development of anemia characteristics. Mice were subjected to unilateral ischemia-reperfusion or received repeated low doses of cisplatin or folic acid to induce nephropathy. Renal function, kidney injury and fibrotic markers were measured to confirm CKD. Moreover, serum hemoglobin, ferritin and erythropoietin were analyzed. Renal mRNA levels of HIF-2α, erythropoietin, hepcidin, GATA-2, and GATA-2 target genes were also determined. All three CKD models presented increased levels of creatinine, urea, and proteinuria. Renal up-regulation of NGAL, KIM-1, and TNF-α mRNA levels was observed. Moreover, the three CKD models developed fibrosis and presented increased fibrotic markers and α-SMA protein levels. CKD induced decreased hemoglobin and ferritin levels and increased erythropoietin levels in the serum. Renal tissue showed decreased erythropoietin and HIF-2α mRNA levels, while an increase in the iron metabolism regulator hepcidin was observed. GATA-2 transcription factor (erythropoietin repressor) mRNA levels were increased in all CKD models, as well as its target genes. We established three models of CKD-induced anemia, regardless of the mechanism and severity of kidney injury.

Analysis of genes associated with proinflammatory and profibrotic pathways upregulated in ischemia-induced chronic kidney disease in cats

OBJECTIVE

To use RNA sequencing (RNAseq) to characterize renal transcriptional activities of genes associated with proinflammatory and profibrotic pathways in ischemia-induced chronic kidney disease (CKD) in cats.

SAMPLES

Banked renal tissues from 6 cats with experimentally induced CKD (renal ischemia [RI] group) and 9 healthy cats (control group).

PROCEDURES

Transcriptome analysis with RNAseq, followed by gene ontology and cluster analyses, were performed on banked tissue samples of the right kidneys (control kidneys) from cats in the control group and of both kidneys from cats in the RI group, in which unilateral (right) RI had been induced 6 months before the cats were euthanized and the ischemic kidneys (IKs) and contralateral nonischemic kidneys (CNIKs) were harvested. Results for the IKs, CNIKs, and control kidneys were compared to identify potential differentially expressed genes and overrepresented proinflammatory and profibrotic pathways.

RESULTS

Genes from the gene ontology pathways of collagen binding (eg, transforming growth factor-β1), metalloendopeptidase activity (eg, metalloproteinase [MMP]-7, MMP-9, MMP-11, MMP-13, MMP-16, MMP-23B, and MMP-28), chemokine activity, and T-cell migration were overrepresented as upregulated in tissue samples of the IKs versus control kidneys. Genes associated with the extracellular matrix (eg, TIMP-1, fibulin-1, secreted phosphoprotein-1, matrix Gla protein, and connective tissue growth factor) were upregulated in tissue samples from both the IKs and CNIKs, compared with tissues from the control kidneys.

CONCLUSIONS AND CLINICAL RELEVANCE

Unilateral ischemic injury differentially altered gene expression in both kidneys, compared with control kidneys. Fibulin-1, secreted phosphoprotein-1, and matrix Gla protein may be candidate biomarkers of active kidney injury in cats.

Mesenchymal Stem Cell-Derived Extracellular Vesicles to the Rescue of Renal Injury

Acute kidney injury (AKI) and chronic kidney disease (CKD) are rising in global prevalence and cause significant morbidity for patients. Current treatments are limited to slowing instead of stabilising or reversing disease progression. In this review, we describe mesenchymal stem cells (MSCs) and their constituents, extracellular vesicles (EVs) as being a novel therapeutic for CKD. MSC-derived EVs (MSC-EVs) are membrane-enclosed particles, including exosomes, which carry genetic information that mimics the phenotype of their cell of origin. MSC-EVs deliver their cargo of mRNA, miRNA, cytokines, and growth factors to target cells as a form of paracrine communication. This genetically reprograms pathophysiological pathways, which are upregulated in renal failure. Since the method of exosome preparation significantly affects the quality and function of MSC-exosomes, this review compares the methodologies for isolating exosomes from MSCs and their role in tissue regeneration. More specifically, it summarises the therapeutic efficacy of MSC-EVs in 60 preclinical animal models of AKI and CKD and the cargo of biomolecules they deliver. MSC-EVs promote tubular proliferation and angiogenesis, and inhibit apoptosis, oxidative stress, inflammation, the epithelial-to-mesenchymal transition, and fibrosis, to alleviate AKI and CKD. By reprogramming these pathophysiological pathways, MSC-EVs can slow or even reverse the progression of AKI to CKD, and therefore offer potential to transform clinical practice.

Extended-release of therapeutic microRNA via a host-guest supramolecular hydrogel to locally alleviate renal interstitial fibrosis

Activated fibroblasts are critical contributors to renal interstitial fibrosis thus becoming the cellular target for fibrosis treatment. Previously, microRNA 29 b (miR-29 b) is shown to be down-regulated in various animal models of renal fibrosis. Herein, we describe a facile strategy to achieve localized and sustained delivery of therapeutic microRNA to the kidney via a host-guest supramolecular hydrogel. Specifically, cationic bovine serum albumin is used to complex with miR-29 b to afford nanocomplexes (cBSA/miR-29 b), which is proven to specifically inhibit fibroblast activation in a dose-dependent manner in vitro. Following unilateral ureteral obstruction in mice, a single injection of the hydrogel loaded with cBSA/miR-29 b in vivo, significantly down-regulated proteins and genes related to fibrosis for up to 21 days without affecting the normal liver or kidney functions. Overall, the localized delivery of cBSA/miR-29 b via a host-guest supramolecular hydrogel represents a safe and effective intervention strategy to delay and reverse the progression of interstitial renal fibrosis.

Diffusion kurtosis imaging for the assessment of renal fibrosis of chronic kidney disease: A preliminary study

PURPOSE

To investigate the potential of diffusion kurtosis imaging (DKI) for the assessment of renal fibrosis in chronic kidney disease (CKD), using histopathology as the reference standard.

METHODS

Eighty-nine CKD patients and twenty healthy volunteers were recruited in this study. DKI was performed in all participants and all CKD patients received renal biopsy. The values of mean diffusivity (MD) and mean kurtosis (MK) in the renal cortex and medulla were compared between CKD patients and healthy volunteers. The Spearman correlation coefficient was calculated to assess the relationship between MD, MK values and the estimated glomerular filtration rate (eGFR), serum creatinine (SCr), 24 h urinary protein (24 h-UPRO), histopathological fibrosis score.

RESULTS

The medullary MD values were significantly lower than cortex, while the cortical MK values were significantly lower than medulla for all participants. Renal parenchymal MD values were significantly lower in the CKD patients than healthy controls, whereas MK values were significantly higher in the CKD patients than healthy controls. In the CKD patients, the significantly negative correlation was observed between the renal parenchymal MD values and the 24 h-UPRO, SCr, histopathological fibrosis score, as well as between the renal parenchymal MK values and the eGFR, while the significantly positive correlation was found between the renal parenchymal MD values and the eGFR, as well as between the renal parenchymal MK values and the 24 h-UPRO, SCr, histopathological fibrosis score.

CONCLUSION

DKI shows great potential in the noninvasive assessment of renal fibrosis in CKD.

Emodin-induced autophagic cell death hinders epithelial-mesenchymal transition via regulation of BMP-7/TGF-β1 in renal fibrosis

We aim to explore the effects of emodin and its mechanisms on renal fibrosis (RF). We firstly modeled adriamycin-induced rat RF with unilateral nephrectomy. In vivo and in vitro pharmacological experiments were performed in this study. The presence of collagen deposition was detected by Masson staining. To verify whether emodin attenuates RF by monitoring autophagy, the immunohistochemistry staining for autophagy protein LC3B was performed. We conducted western blot to detect the expression of the autophagy-related proteins in EMT in vitro model after treating with emotin and BMP-7. In vivo, we demonstrated that emodin could improve renal dysfunction and decrease pathological damage of the kidney by activation of autophagy and inhibition of EMT. Upregulation of BMP-7 was recorded in the RF rats subjected to emodin treatment. In vitro studies, emodin has the capacity of reversing EMT and activating autophagy, and emodin could regulate the expression of BMP-7. The results revealed that the attenuation of EMT by emodin could be blocked after the inhibition of BMP-7 and suppression of autophagy. Our findings demonstrated that emodin alleviates EMT during RF by actuating autophagy through BMP-7, suggesting a role of BMP-7 in RF treatment and prevention.

Diffusion Tensor Imaging in early prediction of renal fibrosis in patients with renal disease: Functional and histopathological correlations

AIM

Renal fibrosis (RF) is a well-known marker of chronic kidney disease (CKD) progression. However, renal biopsy is an available tool for evaluation of RF, non-invasive tools are needed not only to detect but also to monitor the progression of fibrosis. The aim of this study is to evaluate the role of diffusion tensor imaging (DTI) in the assessment of renal dysfunction and RF in patients with renal disease.

METHODS

Fifty-six patients with renal disorders and 22 healthy controls were recruited. All participants underwent DTI. Renal biopsy was performed for all patients. Mean renal medullary and cortical fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were compared between patients and healthy controls and correlated to serum creatinine (SCr), estimated glomerular filtration rate (eGFR), 24-h urinary protein (24h-UPRO) and renal histopathological scores.

RESULTS

Cortical FA values were significantly higher (P = .001), while cortical ADC values were significantly lower in the patients' group (P = .002). Cortical FA values positively correlated to SCr (P = .006) and negatively correlated to eGFR (P = .03), while cortical ADC negatively correlated to percentage of sclerotic glomeruli, atrophic tubules and interstitial fibrosis (P = .001 for all variables). Medullary ADC negatively correlated to tubular atrophy (P = .02). The diagnostic performance of DTI for detecting RF was supported by ROC curve. Multiple linear regression analysis revealed that the mean cortex ADC was significantly decreased by 0.199 mg/dL for patients with >50% glomerulosclerosis in renal biopsy.

CONCLUSION

DTI appears to represent a valuable tool for the non-invasive assessment of renal dysfunction and renal fibrosis.

Caffeic Acid, One of the Major Phenolic Acids of the Medicinal Plant Antirhea borbonica, Reduces Renal Tubulointerstitial Fibrosis

The renal fibrotic process is characterized by a chronic inflammatory state and oxidative stress. Antirhea borbonica (A. borbonica) is a French medicinal plant found in Reunion Island and known for its antioxidant and anti-inflammatory activities mostly related to its high polyphenols content. We investigated whether oral administration of polyphenol-rich extract from A. borbonica could exert in vivo a curative anti-renal fibrosis effect. To this aim, three days after unilateral ureteral obstruction (UUO), mice were daily orally treated either with a non-toxic dose of polyphenol-rich extract from A. borbonica or with caffeic acid (CA) for 5 days. The polyphenol-rich extract from A. borbonica, as well as CA, the predominant phenolic acid of this medicinal plant, exerted a nephroprotective effect through the reduction in the three phases of the fibrotic process: (i) macrophage infiltration, (ii) myofibroblast appearance and (iii) extracellular matrix accumulation. These effects were associated with the mRNA down-regulation of Tgf-β, Tnf-α, Mcp1 and NfkB, as well as the upregulation of Nrf2. Importantly, we observed an increased antioxidant enzyme activity for GPX and Cu/ZnSOD. Last but not least, desorption electrospray ionization-high resolution/mass spectrometry (DESI-HR/MS) imaging allowed us to visualize, for the first time, CA in the kidney tissue. The present study demonstrates that polyphenol-rich extract from A. borbonica significantly improves, in a curative way, renal tubulointerstitial fibrosis progression in the UUO mouse model.

A Metabolic Reprogramming of Glycolysis and Glutamine Metabolism Is a Requisite for Renal Fibrogenesis-Why and How?

Chronic Kidney Disease (CKD) is characterized by organ remodeling and fibrosis due to failed wound repair after on-going or severe injury. Key to this process is the continued activation and presence of matrix-producing renal fibroblasts. In cancer, metabolic alterations help cells to acquire and maintain a malignant phenotype. More recent evidence suggests that something similar occurs in the fibroblast during activation. To support these functions, pro-fibrotic signals released in response to injury induce metabolic reprograming to meet the high bioenergetic and biosynthetic demands of the (myo)fibroblastic phenotype. Fibrogenic signals such as TGF-β1 trigger a rewiring of cellular metabolism with a shift toward glycolysis, uncoupling from mitochondrial oxidative phosphorylation, and enhanced glutamine metabolism. These adaptations may also have more widespread implications with redirection of acetyl-CoA directly linking changes in cellular metabolism and regulatory protein acetylation. Evidence also suggests that injury primes cells to these metabolic responses. In this review we discuss the key metabolic events that have led to a reappraisal of the regulation of fibroblast differentiation and function in CKD.

Intratumoral Fibrosis in Facilitating Renal Cancer Aggressiveness: Underlying Mechanisms and Promising Targets

Intratumoral fibrosis is a histologic manifestation of fibrotic tumor stroma. The interaction between cancer cells and fibrotic stroma is intricate and reciprocal, involving dysregulations from multiple biological processes. Different components of tumor stroma are implicated via distinct manners. In the kidney, intratumoral fibrosis is frequently observed in renal cell carcinoma (RCC). However, the underlying mechanisms remain largely unclear. In this review, we recapitulate evidence demonstrating how fibrotic stroma interacts with cancer cells and mechanisms shared between RCC tumorigenesis and renal fibrogenesis, providing promising targets for future studies.

Spectrum of cancer patients receiving renal biopsy

BACKGROUND

The frontier of onco-nephrology, particularly renal complications of cancer and treatment, remains unexplored. We revisit the fundamental tool of diagnosing kidney disease, renal biopsy, in cancer patients with renal manifestation.

METHODS

Patients who received renal biopsy from July 2015 to July 2019 were analyzed. Primary outcomes included end-stage renal disease (ESRD), mortality, and catastrophic outcome defined as either ESRD or mortality. A Cox proportional hazards model and Kaplan-Meier technique were used to assess the association with outcome measurements and survival analyses. Immunosuppression after renal biopsy and response to the treatment were evaluated.

RESULTS

Among the 77 patients, the median age was 66 years (interquartile range [IQR] 59-73 years) and 46 (59.7%) were male. At the time of renal biopsy, 57 patients (74%) had various degrees of renal insufficiency. Tubulointerstitial damage score, quantified by renal pathology, were associated with higher hazards of ESRD (hazard ratio [HR], 1.77; 95% confidence interval [95% CI], 1.20 to 2.61; P = 0.004) and catastrophic outcome (HR, 1.30; 95% CI, 0.99 to 1.70; P = 0.058). The response rate to immunosuppression was lower in those diagnosed with tubulointerstitial nephritis (1 of 4 patients, 25%) than those with glomerulopathy (10 of 20 patients, 50%).

CONCLUSION

Renal biopsy may improve diagnostic accuracy and assist in treatment guidance of cancer patients with renal manifestation. Renal biopsy should be encouraged with clinical indication. Collaboration between oncologists and nephrologists is of paramount importance to provide more comprehensive care for caner patients.

Evaluation of Renal Fibrosis by Mapping Histology and Magnetic Resonance Imaging

Background

Renal fibrosis is a key driver of progression in chronic kidney disease (CKD). Recent advances in diagnostic imaging techniques have shown promising results for the noninvasive assessment of renal fibrosis. However, the specificity and accuracy of these techniques are controversial because they indirectly assess renal fibrosis. This limits fibrosis assessment by imaging in CKD for clinical practice. To validate magnetic resonance imaging (MRI) assessment for fibrosis, we derived representative models by mapping histology-proven renal fibrosis and imaging in CKD.

Methods

Ninety-seven adult Chinese CKD participants with histology were studied. The kidney cortex interstitial extracellular matrix volume was calculated by the Aperio ScanScope system using Masson's trichrome slices. The kidney cortex microcirculation was quantitatively assessed by peritubular capillary density using CD34 staining. The imaging techniques included intravoxel incoherent motion diffusion-weighted imaging and magnetic resonance elastography (MRE) imaging. Relevant analyses were performed to evaluate the correlations between MRI parameters and histology variables. Multiple linear regression models were used to describe the relationships between a response variable and other variables. The best-fit lines, which minimize the sum of squared residuals of the multiple linear regression models, were generated.

Results

MRE values were negatively associated with the interstitial extracellular matrix volume (Rho = -0.397, p < 0.001). The best mapping model of extracellular matrix volume with the MRE value and estimated glomerular filtration rate (eGFR) we obtained was as follows: Interstitial extracellular matrix volume = 218.504 - 14.651 × In(MRE) - 18.499 × In(eGFR). DWI-fraction values were positively associated with peritubular capillary density (Rho = 0.472, p < 0.001). The best mapping model of peritubular capillary density with DWI-fraction value and eGFR was as follows: Peritubular capillaries density = 17.914 + 9.403 × (DWI - fraction) + 0.112 × (eGFR).

Conclusions

The study provides histological evidence to support that MRI can effectively evaluate fibrosis in the kidney. These findings picture the graphs of the mapping model from imaging and eGFR into fibrosis, which has significant value for clinical implementation.

Charateristics of Gynecological Abnormalities and Types of Urine Diversion at Dr Soetomo Hospital, Surabaya, Indonesia, in Three-Year Period

In the case of advanced stage gynecological disorders, most patients have a disturbance in the upper urinary tract. Most patients with uterine cervical carcinoma are already in stage 3B and require urine diversion. The purpose of this study is to find and determine the profile of gynecological disorders that require urine diversion, the type of urine diversion, and urine diverted output in patients with cervical carcinoma. This descriptive analytical retrospective study was conducted at Dr. Soetomo Hospital, Surabaya, Indonesia, between 2012 and 2015. The samples of this study were all patients with gynecological disorders who underwent retrograde DJ stent procedures, underwent ureterocutaneostomy and nephrostomy at the Integrated Central Surgery Building, Dr. Soetomo Hospital, Surabaya, for three years between 2012 and 2015. Data was collected based on the medical record number of patients with gynecological disorders who underwent urine diversion procedures and were recorded in the book on the operation schedule. We find that the most common cause of gynecological abnormalities in kidney obstruction is cervical carcinoma. There are three types of urine diversions used, namely DJ stent, percutaneous nefropyelostomy, and ureterocutaneostomy, with DJ as the most commonly performed. Urine diversion can improve creatinine without being influenced by the type of diversity.

Integrated multi-omics approaches to improve classification of chronic kidney disease

Chronic kidney diseases (CKDs) are currently classified according to their clinical features, associated comorbidities and pattern of injury on biopsy. Even within a given classification, considerable variation exists in disease presentation, progression and response to therapy, highlighting heterogeneity in the underlying biological mechanisms. As a result, patients and clinicians experience uncertainty when considering optimal treatment approaches and risk projection. Technological advances now enable large-scale datasets, including DNA and RNA sequence data, proteomics and metabolomics data, to be captured from individuals and groups of patients along the genotype-phenotype continuum of CKD. The ability to combine these high-dimensional datasets, in which the number of variables exceeds the number of clinical outcome observations, using computational approaches such as machine learning, provides an opportunity to re-classify patients into molecularly defined subgroups that better reflect underlying disease mechanisms. Patients with CKD are uniquely poised to benefit from these integrative, multi-omics approaches since the kidney biopsy, blood and urine samples used to generate these different types of molecular data are frequently obtained during routine clinical care. The ultimate goal of developing an integrated molecular classification is to improve diagnostic classification, risk stratification and assignment of molecular, disease-specific therapies to improve the care of patients with CKD.

Application of creeping flow through a linearly absorbing slit filled with porous medium to diseased renal tubules

In this paper, we have discussed the flow of a Newtonian fluid through a slit filled with porous medium and linearly reabsorbing porous walls. The study is motivated by fluid flow in diseased renal tubules in a kidney. Due to diseases, some fibrous material, fatty substances and solid waste particles, etc., may get suspended in tubule channel as well as on the pores of the wall, resulting in the porous filling in the slit and biofouling, respectively. In this study, the absorption at the wall is assumed to follow a linear pattern and the fluid is assumed to be entering the channel at a prescribed initial flow rate. The problem of the two-dimensional fluid flow is formulated using stream function, and inverse solution method is applied to obtain an exact solution of the fourth-order compatibility equation. Some special cases are also deduced from the obtained results and compared with available results from literature. Expressions for various physically relevant quantities like fluid velocities, volume flow rate, fractional reabsorption, leakage flux and pressure distribution are obtained. The results are used to demonstrate how medium porosity and biofouling parameter may affect average pressure differences in the renal tubules of a rat kidney. Finally, the results are presented graphically and effects of changing various parameters on the flow are analysed. We have also deduced some special cases when the wall reabsorption is uniform, and when there is no medium porosity. We have shown these special cases match with the already present results in the literature.

TGF-β1 is a regulator of the pyruvate dehydrogenase complex in fibroblasts

TGF-β1 reprograms metabolism in renal fibroblasts, inducing a switch from oxidative phosphorylation to aerobic glycolysis. However, molecular events underpinning this are unknown. Here we identify that TGF-β1 downregulates acetyl-CoA biosynthesis via regulation of the pyruvate dehydrogenase complex (PDC). Flow cytometry showed that TGF-β1 reduced the PDC subunit PDH-E1α in fibroblasts derived from injured, but not normal kidneys. An increase in expression of PDH kinase 1 (PDK1), and reduction in the phosphatase PDP1, were commensurate with net phosphorylation and inactivation of PDC. Over-expression of mutant PDH-E1α, resistant to phosphorylation, ameliorated effects of TGF-β1, while inhibition of PDC activity with CPI-613 was sufficient to induce αSMA and pro-collagen I expression, markers of myofibroblast differentiation and fibroblast activation. The effect of TGF-β1 on PDC activity, acetyl-CoA, αSMA and pro-collagen I was also ameliorated by sodium dichloroacetate, a small molecule inhibitor of PDK. A reduction in acetyl-CoA, and therefore acetylation substrate, also resulted in a generalised loss of protein acetylation with TGF-β1. In conclusion, TGF-β1 in part regulates fibroblast activation via effects on PDC activity.

Tripartite motif-containing 35 (TRIM35) is up-regulated in UUO-induced renal fibrosis animal model

Renal fibrosis has been recognized as a serious health threat in the world because of the high cost of treatment and poor prognosis. However, the molecular mechanism of renal fibrosis is still largely unknown. In this study, we aimed at illustrating the role of TRIM35 in the renal fibrosis process. A UUO mouse model and a TGF-β1-induced tubulointerstitial fibrosis model were constructed for the research of renal fibrosis at animal and cell level, respectively. Hematoxylin-eosin and Masson staining were used for visualizing the pathological change. qRT-PCR, Western blot analysis and immunohistochemical staining were used to detect the expression of fibrosis-associated proteins and TRIM35. The results showed that, after the modeling, the expressions of α-SMA, Collagen I, Collagen III, Fibronectin and Snail1 were up-regulated, while the expression of E-cadherin was down-regulated, indicating the successful construction of animal and cell models. More importantly, TRIM35 was proved to be up-regulated in both animal and cell models. Therefore, this study demonstrates the potential promotional effect of TRIM35 in the renal fibrosis process, which may prove to be a new biomarker for the diagnosis and development of new treatments of renal fibrosis.

Progress in drug delivery system for fibrosis therapy

Fibrosis is a necessary process in the progression of chronic disease to cirrhosis or even cancer, which is a serious disease threatening human health. Recent studies have shown that the early treatment of fibrosis is turning point and particularly important. Therefore, how to reverse fibrosis has become the focus and research hotspot in recent years. So far, the considerable progress has been made in the development of effective anti-fibrosis drugs and targeted drug delivery. Moreover, the existing research results will lay the foundation for more breakthrough delivery systems to achieve better anti-fibrosis effects. Herein, this review summaries anti-fibrosis delivery systems focused on three major organ fibrotic diseases such as liver, pulmonary, and renal fibrosis accompanied by the elaboration of relevant pathological mechanisms, which will provide inspiration and guidance for the design of fibrosis drugs and therapeutic systems in the future.

Impact of Heparanse on Organ Fibrosis

Organ fibrosis is defined as a deregulated wound-healing process characterized by a progressive accumulation of fibrous tissue and by reduced remodeling that can lead to the loss of functionality of the affected organ. This pathological process is quite common in several parenchymal organs such as kidneys, liver, and lungs and represents a real health emergency in developed western countries since a real anti-fibrotic therapy is not yet available in most cases. Heparanase (HPSE), which is the enzyme that cuts off the side chains of heparan sulfate (HS) proteoglycan, appears to be involved in the aetiopathogenesis of fibrosis in all these organs, even if with different mechanisms. Here we discuss how the interplay between HPSE and components of the immune and inflammatory responses can activate recruitment, proliferation, and activation of myofibroblasts which represent the main cell type responsible for the deposition of fibrous matrix. Finally, bearing in mind that once the activity of HPSE is inhibited no other molecule is able to perform the same function, it is desirable that this enzyme could prove to be a suitable pharmacological target in anti-fibrotic therapy.

NF-κB and tPA Signaling in Kidney and Other Diseases

The activation of the nuclear factor-κB (NF-κB) pathway plays a central role in the initiation and progression of inflammation, which contributes to the pathogenesis and progression of various human diseases including kidney, brain, and other diseases. Tissue plasminogen activator (tPA), a serine protease regulating homeostasis of blood coagulation, fibrinolysis, and matrix degradation, has been shown to act as a cytokine to trigger profound receptor-mediated intracellular events, modulate the NF-κB pathway, and mediate organ dysfunction and injury. In this review, we focus on the current understanding of NF-κB and tPA signaling in the development and progression of kidney disease. Their roles in the nervous and cardiovascular system are also briefly discussed.

The Effect of Low-Power Laser Therapy on the TGF/β Signaling Pathway in Chronic Kidney Disease: A Review

Objective: The purpose of this study is to investigate the effects of low-power lasers on kidney disease by investigating several studies. Methods: A number of articles from 1998 to 2019 were chosen from the sources of PubMed, Scopus, and only the articles studying the effect of low-power lasers on kidney disease were investigated. Results: After reviewing the literature, 21 articles examining only the effects of low-power lasers on kidney disease were found. The results of these studies showed that the parameter of the lowpower laser would result in different outcomes. So, a low-power laser with various parameters can be effective in the treatment of kidney diseases such as acute kidney disease, diabetes, glomerulonephritis, nephrectomy, metabolic syndrome, and kidney fibrosis. Most studies have shown that low-power lasers can affect TGFβ1 signaling which is the most important signaling in the treatment of renal fibrosis. Conclusion: Lasers can be effective in reducing or enhancing inflammatory responses, reducing fibrosis factors, and decreasing reactive oxygen species (ROS) levels in kidney disease and glomerular cell proliferation.

Silibinin enhances anti-renal fibrosis effect of MK-521 via downregulation of TGF-β signaling pathway

Renal fibrosis is a common characteristic of chronic kidney disease (CKD), and it can lead to end-stage renal disease. It has been reported that silibinin or lisinopril (MK-521) can inhibit the progression of renal fibrosis. However, the effect of combination of silibinin with MK-521 on renal fibrosis remains unclear. Therefore, this study aimed to explore the combination of silibinin with MK-521 on renal fibrosis in vitro and in vivo. The cell viability of HK-2 was detected by CCK-8. The gene and protein expression in HK-2 cells were detected by qRT-PCR and Western blot, respectively. Moreover, HFD-induced renal fibrosis mouse model was established to investigate the effect of silibinin in combination with MK-521 on renal fibrosis in vivo. The expressions of collagen I, α-SMA, Smad2 and Smad3 in TGF-β-treated HK-2 cells were notably decreased by MK-521, which was further inhibited in the presence of silibinin. In addition, we found that silibinin significantly enhanced anti-fibrotic effect of MK-521 on HFD-induced renal fibrosis mice. These findings demonstrated that silibinin could significantly increase anti-fibrotic effect of MK-521 in vitro and in vivo. Therefore, the combination of silibinin with MK-521 may serve as a potential strategy for the treatment of renal fibrosis.

FFNT25 ameliorates unilateral ureteral obstruction-induced renal fibrosis

Renal fibrosis is a common pathological feature of chronic kidney disease (CKD) patients who progress to end-stage renal disease (ESRD). With the increasing incidence of CKD, it is of importance to develop effective therapies that blunt development of renal fibrosis. FFNT25 is a newly developed molecular compound that could be used to prevent fibrosis. In this study, we administered FFNT25 to rats following unilateral ureteral obstruction (UUO) to investigate its anti-fibrosis mechanism. Thirty-two Sprague-Dawley rats were randomly divided into four groups: (1) control (normal rats), (2) sham-operated, (3) UUO-operated + vehicle, and (4) UUO-operated + FFNT25. Two weeks after UUO, the rats were gavaged with either FFNT25 (20.6 mg/kg/day) or vehicle for two weeks. Serum, urine, and kidney samples were collected at the end of the study. FFNT25 reduced levels of renal fibrosis and decreased mRNA and protein levels of extracellular matrix (ECM) markers α-smooth muscle actin (α-SMA) and plasminogen activator inhibitor-1 (PAI-1) following UUO compared to vehicle treatment (n = 8, p<.05). The current results indicate that FFNT25 can affect both the production and degradation of collagen fibers to reduce fibrosis.

Emodin Retarded Renal Fibrosis Through Regulating HGF and TGFβ-Smad Signaling Pathway

BACKGROUND

Renal fibrosis is a frequently occurring type of chronic kidney disease that can cause end-stage renal disease. It has been verified that emodin or HGF can inhibit the development of renal fibrosis. However, the antifibrotic effect of emodin in combination with HGF remains unclear.

METHODS

Cell viability was detected with CCK8. Gene and protein expression in HK2 cells was detected by qRT-PCR and Western blot, respectively. Moreover, a unilateral ureteral obstruction-induced mouse model of renal fibrosis was established for investigating the antifibrotic effect of emodin in combination with HGF in vivo.

RESULTS

HGF notably increased the expression of collagen II in TGFβ-treated HK2 cells. In addition, HGF-induced increase in collagen II expression was further enhanced by emodin. In contrast, fibronectin, αSMA and Smad2 expression in TGFβ-stimulated HK2 cells was significantly inhibited by HGF and further decreased by combination treatment (emodin plus HGF). Moreover, we found that combination treatment exhibited better antifibrotic effects compared with emodin or HGF in vivo.

CONCLUSION

These data demonstrated that emodin plus HGF exhibited better antifibrotic effects compared with emodin or HGF. As such, emodin in combination with HGF may serve as a new possibilty for treatment of renal fibrosis.