Using elastography-based multilayer perceptron model to evaluate renal fibrosis in chronic kidney disease

BACKGROUND

Given its progressive deterioration in the clinical course, noninvasive assessment and risk stratification for the severity of renal fibrosis in chronic kidney disease (CKD) are required. We aimed to develop and validate an end-to-end multilayer perceptron (MLP) model for assessing renal fibrosis in CKD patients based on real-time two-dimensional shear wave elastography (2D-SWE) and clinical variables.

METHODS

From April 2019 to December 2021, a total of 162 patients with CKD who underwent a kidney biopsy and 2D-SWE examination were included in this single-center, cross-sectional, and prospective clinical study. 2D-SWE was performed to measure the right renal cortex stiffness, and the corresponding elastic values were recorded. Patients were categorized into two groups according to their histopathological results: mild and moderate-severe renal fibrosis. The patients were randomly divided into a training cohort (n = 114) or a test cohort (n = 48). The MLP classifier using a machine learning algorithm was used to construct a diagnostic model incorporating elastic values with clinical features. Discrimination, calibration, and clinical utility were used to appraise the performance of the established MLP model in the training and test sets, respectively.

RESULTS

The developed MLP model demonstrated good calibration and discrimination in both the training [area under the receiver operating characteristic curve (AUC) = 0.93; 95% confidence interval (CI) = 0.88 to 0.98] and test cohorts [AUC = 0.86; 95% CI = 0.75 to 0.97]. A decision curve analysis and a clinical impact curve also showed that the MLP model had a positive clinical impact and relatively few negative effects.

CONCLUSIONS

The proposed MLP model exhibited the satisfactory performance in identifying the individualized risk of moderate-severe renal fibrosis in patients with CKD, which is potentially helpful for clinical management and treatment decision-making.

Exploration of the mechanism of NORAD activation of TGF-β1/Smad3 through miR-136-5p and promotion of tacrolimus-induced renal fibrosis

BACKGROUND

Tacrolimus is a potent immunosuppressant, but has various side effects, with nephrotoxicity being the most common. Renal fibrosis is an important process of tacrolimus nephrotoxicity. Therefore, it is important to identify the factors that contribute to renal fibrosis after tacrolimus nephrotoxicity, and control its development.

METHODS

The present study aims to determine whether tacrolimus may speed up the course of renal fibrosis by upregulating noncoding RNA activated by DNA damage (NORAD) to compete with miR-136-5p, and activating the TGF-β1/Smad3 pathway. Furthermore, in vivo rat models and in vitro cell models were established. Then, the expression levels of NORAD and miR-136-5p were determined by RT-qPCR, while the expression of the TGF-β1/Smad3 pathway was determined by western blot and RT-qPCR. In order to investigate the interaction between NORAD and miR-136-5p, as well as miR-136-5p and SYK, two luciferase reporters were employed. The renal fibrosis of mice was observed using Masson and PAS staining. The expression of inflammatory factors IL-1, IL-6, MCP-1 and TNF-α was detected by ELISA.

RESULTS

In the in vitro experiments, NORAD was upregulated, while miR-136-5p was downregulated after tacrolimus induction. The expression of the TGF-β1/Smad3 pathway correspondingly changed after the induction by tacrolimus. In the in vivo experiments, the expression of NORAD and miR-136-5p, and the trend for renal fibrosis were consistent with the results in the in vitro experiments. Furthermore, the inflammatory factors correspondingly changed with the severity of renal fibrosis. Moreover, the expression trend of the TGF-β1/Smad3 pathway in tacrolimus-induced rats was consistent with that in the in vitro experiments.

CONCLUSION

Through in vitro and in vivo experiments, the present study was able to successfully prove that tacrolimus upregulates NORAD to compete with miR-136-5p, resulting in a decrease in miR-136-5p expression, which in turn activates the TGF-β1/smad3 pathway, and finally induces the aggravation of renal fibrosis.

Depletion of macrophages with clodronate liposomes partially attenuates renal fibrosis on AKI-CKD transition

Clodronate liposomes are bisphosphonates encapsulated by liposomes that are known to induce macrophage depletion in vivo. In a previous study, clodronate liposomes improved renal ischemia/reperfusion (I/R) injury in mice, which may be due to effects on macrophage phenotypes. However, how inflammatory cytokines secretion participates is unknown. In this study, we investigated the effect of macrophages in the I/R kidney by depleting macrophages with clodronate liposomes and changing inflammatory cytokines. C57BL/6 mice underwent I/R injury with or without clodronate liposomes administration on Days 5 and 15. Tubular injury, collagen deposition, and fibrosis were detected and analyzed by histological staining, immunocytochemistry (IHC), flow cytometry (FACS), and reverse transcription-polymerase chain reaction (RT-PCR). Inflammatory cytokines were detected and analyzed by Western blotting and RT-PCR. We found that clodronate liposomes alleviated renal fibrosis and tissue damage on both Days 5 and 15. KIM-1, IL-10, and TGF-β were reduced significantly in the clodronate liposomes treatment group. However, TNF-α was not different between the clodronate liposomes treatment group and the phosphate-buffered saline treatment group on either Day 5 or Day 15. Thus, clodronate liposomes can alleviate renal fibrosis and tissue damage and reduce the inflammatory cytokines IL-10 and TGF-β, suggesting that clodronate liposomes alleviate renal fibrosis may because of M1/M2 polarization.

The kidney antifibrotic effects of 5,7,3',4',5'-pentamethoxyflavone from Bauhinia championii in streptozotocin-induced diabetic rats: in vivo and in vitro experiments

CONTEXT

The antidiabetic effects of flavonoids have been reported, but it is still unclear whether 5,7,3',4',5'-pentamethoxyflavone, isolated from Bauhinia championii Benth. (Fabaceae), also exhibits such properties.

OBJECTIVE

To isolate 5,7,3',4',5'-pentamethoxyflavone from B. championii using high-speed countercurrent chromatography and examine its potential in treating diabetic nephropathy.

MATERIALS AND METHODS

The phytochemical constituents from the stems of B. championii were separated and purified with high-speed countercurrent chromatography; 5,7,3',4',5'-pentamethoxyflavone (PMF) was identified by mass spectrum, ¹H-NMR, and ¹³C-NMR. After exposing mesangial cells to 30 mM glucose and either 5 μM or 10 μM PMF for 6 h, the levels of fibronectin (FN) and p-Smad2/3 were analyzed using Western blotting. Male Sprague-Dawley rats were injected intraperitoneally with 55 mg/kg streptozotocin to induce diabetes and then were randomized into three groups (n = 10): vehicle administration, low-dose (5 mg/kg) PMF, and high-dose (25 mg/kg) PMF by intragastric gavage for 3 months. A healthy group was included as the control.

RESULTS

Compared to the diabetic group, low-dose and high-dose PMF treatment decreased the phosphorylation of Smad2/3 by 0.54- and 0.52-fold, and the accumulation of FN decreased by 0.82- and 0.77-fold in vitro; the phosphorylation of Smad2/3 was decreased by 0.39- and 0.37-fold, and the accumulation of FN decreased by 0.47- and 0.40-fold in vivo, respectively. Furthermore, PMF alleviated the glomerular basement membrane thickness and foot process fusion.

CONCLUSION

The findings suggest for the first time that PMF may be a promising treatment option for diabetic kidney fibrosis, which warrants additional clinical investigation.

Combination therapy with DHA and BMSCs suppressed podocyte injury and attenuated renal fibrosis by modulating the TGF-β1/Smad pathway in MN mice

Artemisinin has immunomodulatory, anti-inflammatory, and antifibrotic effects. Some studies have demonstrated that artemisinins have a protective effect on the kidney. DHA is a derivative of artemisinin and has effects similar to those of artemisinin. Human bone marrow-derived mesenchymal stem cells (BMSCs) accelerate renal repair following acute injury. In the study, we investigated the effects of combination therapy with DHA and BMSCs on membranous nephropathy (MN) mice. The 24-h urinary protein, serum total cholesterol (TC) and triglyceride (TG) levels, and renal histopathology, were measured to evaluate kidney damage. Anti-PLA2R, IgG, and complement 3 (C3) were detected by ELISA. The expression levels of the podocyte injury-related proteins were analyzed by immunohistochemistry. The protein expression levels of α-SMA, ED-1, TGF-β1, p-Smad2, and p-Smad3 were detected by western blot to analyze renal fibrosis and its regulatory mechanism. Results showed that combination therapy with DHA and BMSCs significantly ameliorated kidney damage in MN model mice by decreasing the levels of 24 h urinary protein, TC and TG. This combination therapy also improved renal histology and reduced the expression of IgG and C3 in the glomerulus. In addition, this combination therapy decreased the expression of podocin and nephrin and relieved renal fibrosis by downregulating α-SMA and ED-1. Furthermore, this combination therapy suppressed TGF-β1 expression and Smad2/3 phosphorylation. This result (i.e., this combination therapy inhibited the TGF-β1/Smad pathway) was also supported in vitro. Taken together, combination therapy with DHA and BMSCs ameliorated podocyte injury and renal fibrosis in MN mice by downregulating the TGFβ1/Smad pathway.

Hypoxia and renal fibrosis

Renal fibrosis is the final stage of most progressive kidney diseases. Chronic kidney disease (CKD) is associated with high comorbidity and mortality. Thus, preventing fibrosis and thereby preserving kidney function increases the quality of life and prolongs the survival of patients with CKD. Many processes such as inflammation or metabolic stress modulate the progression of kidney fibrosis. Hypoxia has also been implicated in the pathogenesis of renal fibrosis, and oxygen sensing in the kidney is of outstanding importance for the body. The dysregulation of oxygen sensing in the diseased kidney is best exemplified by the loss of stimulation of erythropoietin production from interstitial cells in the fibrotic kidney despite anemia. Furthermore, hypoxia is present in acute or chronic kidney diseases and may affect all cell types present in the kidney including tubular and glomerular cells as well as resident immune cells. Pro- and antifibrotic effects of the transcription factors hypoxia-inducible factors 1 and 2 have been described in a plethora of animal models of acute and chronic kidney diseases, but recent advances in sequencing technologies now allow for novel and deeper insights into the role of hypoxia and its cell type-specific effects on the progression of renal fibrosis, especially in humans. Here, we review existing literature on how hypoxia impacts the development and progression of renal fibrosis.

Sinomenine improves renal fibrosis by regulating mesenchymal stem cell-derived exosomes and affecting autophagy levels

BACKGROUND

This study attempts to investigate the therapeutic effect of sinomenine on renal fibrosis and its mechanism.

METHODS

The 8-week-old C57BL/6 male mice were randomly divided into sham group, UUO model group, UUO sinomenine group (UUO + Sino 50), UUO + sinomenine group (UUO + Sino 100), UUO + exosome group (exo), and UUO + exo-inhibitor. The pathological changes of kidney were observed by H&E staining, the degree of renal interstitial fibrosis was detected by MASSON and Sirius red staining, and the expressions of fibrosis and autophagy markers were detected by real-time fluorescence quantitative PCR and WB. NTA and electron microscopy were used to analyze exo secretion after sinomenine treatment.

RESULTS

Sinomenine could improve the progression of renal fibrosis without causing tissue damage including heart, lungs and liver. Sinomenine could promote autophagosome formation. It could promote the secretion of exosomes from bone marrow mesenchymal stem cells (BMSCs). Sinomine regulates the PI3K-AKT pathway through BMSC-exo carrying miR-204-5p, affecting autophagy level and alleviating the process of renal fibrosis.

CONCLUSION

Our study suggests that sinomine could improve the progression of renal fibrosis by influencing the expression of miR-204-5p in BMSC-exo and regulating the PI3K-AKT pathway.

Caloric Restriction Mitigates Kidney Fibrosis in an Aged and Obese Rat Model

Caloric restriction is an effective intervention to protract healthspan and lifespan in several animal models from yeast to primates, including humans. Caloric restriction has been found to induce cardiometabolic adaptations associated with improved health and to delay the onset and progression of kidney disease in different species, particularly in rodent models. In both aging and obesity, fibrosis is a hallmark of kidney disease, and epithelial-mesenchymal transition is a key process that leads to fibrosis and renal dysfunction during aging. In this study, we used an aged and obese rat model to evaluate the effect of long-term (6 months) caloric restriction (-40%) on renal damage both from a structural and functional point of view. Renal interstitial fibrosis was analyzed by histological techniques, whereas effects on mesenchymal (N-cadherin, Vimentin, Desmin and α-SMA), antioxidant (SOD1, SOD2, Catalase and GSTP1) inflammatory (YM1 and iNOS) markers and apoptotic/cell cycle (BAX, BCL2, pJNK, Caspase 3 and p27) pathways were investigated using Western blot analysis. Our results clearly showed that caloric restriction promotes cell cycle division and reduces apoptotic injury and fibrosis phenotype through inflammation attenuation and leukocyte infiltration. In conclusion, we highlight the beneficial effects of caloric restriction to preserve elderly kidney function.

Omega-3 Fatty Acids Attenuate Renal Fibrosis via AMPK-Mediated Autophagy Flux Activation

The unilateral ureteral obstruction (UUO) injury model is well-known to mimic human chronic kidney disease, promoting the rapid onset and development of kidney injury. ω3-poly unsaturated fatty acids (PUFAs) have been observed to protect against tissue injury in many disease models. In this study, we assessed the efficacy of ω3-PUFAs in attenuating UUO injury and investigated their mechanism of action. The immortalized human proximal tubular cells human kidney-2 (HK2) were incubated for 72 h with docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) in various concentrations, in the presence or absence of transforming growth factor (TGF)-β. DHA/EPA reduced the epithelial-mesenchymal transition in the TGF-β-treated HK2 cells by enhancing autophagy flux and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. C57BL/6 mice were divided into four groups and treated as follows: sham (no treatment, n = 5), sham + ω3-PUFAs (n = 5), UUO (n = 10), and UUO + ω3-PUFAs (n = 10). Their kidneys and blood were harvested on the seventh day following UUO injury. The kidneys of the ω3-PUFAs-treated UUO mice showed less oxidative stress, inflammation, and fibrosis compared to those of the untreated UUO mice. Greater autophagic flux, higher amounts of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, Beclin-1, and Atg7, lower amounts of p62, and higher levels of cathepsin D and ATP6E were observed in the kidneys of the omega-3-treated UUO mice compared to those of the control UUO mice. In conclusion, ω3-PUFAs enhanced autophagic activation, leading to a renoprotective response against chronic kidney injury.

Endothelial cell plasticity in kidney fibrosis and disease

Renal endothelial cells demonstrate an impressive remodeling potential during angiogenic sprouting, vessel repair or while transitioning into mesenchymal cells. These different processes may play important roles in both renal disease progression or regeneration while underlying signaling pathways of different endothelial cell plasticity routes partly overlap. Angiogenesis contributes to wound healing after kidney injury and pharmaceutical modulation of angiogenesis may home a great therapeutic potential. Yet, it is not clear whether any differentiated endothelial cell can proliferate or whether regenerative processes are largely controlled by resident or circulating endothelial progenitor cells. In the glomerular compartment for example, a distinct endothelial progenitor cell population may remodel the glomerular endothelium after injury. Endothelial-to-mesenchymal transition (EndoMT) in the kidney is vastly documented and often associated with endothelial dysfunction, fibrosis, and kidney disease progression. Especially the role of EndoMT in renal fibrosis is controversial. Studies on EndoMT in vivo determined possible conclusions on the pathophysiological role of EndoMT in the kidney, but whether endothelial cells really contribute to kidney fibrosis and if not what other cellular and functional outcomes derive from EndoMT in kidney disease is unclear. Sequencing data, however, suggest no participation of endothelial cells in extracellular matrix deposition. Thus, more in-depth classification of cellular markers and the fate of EndoMT cells in the kidney is needed. In this review, we describe different signaling pathways of endothelial plasticity, outline methodological approaches and evidence for functional and structural implications of angiogenesis and EndoMT in the kidney, and eventually discuss controversial aspects in the literature.

Relationship between ferroptosis and mitophagy in renal fibrosis: a systematic review

Renal fibrosis, characterised by glomerulosclerosis and tubulointerstitial fibrosis, is a typical pathological alteration in the progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD). However, the limited and expensive options for treating renal fibrosis place a heavy financial burden on patients and healthcare systems. Therefore, it is significant to find an effective treatment for renal fibrosis. Ferroptosis, a non-traditional form of cell death, has been found to play an important role in acute kidney injury (AKI), tumours, neurodegenerative diseases, and so on. Moreover, a growing body of research suggests that ferroptosis might be a potential target of renal fibrosis. Meanwhile, mitophagy is a type of selective autophagy that can selectively degrade damaged or dysfunctional mitochondria as a form of mitochondrial quality control, reducing the production of reactive oxygen species (ROS), the accumulation of which is the main cause of renal fibrosis. Additionally, as a receptor of mitophagy, NIX can release beclin1 to induce mitophagy, which can also bind to solute carrier family 7 member 11 (SLC7A11) to block the activity of cystine/glutamate antitransporter (system Xc-) and inhibit ferroptosis, thereby suggesting a link between mitophagy and ferroptosis. However, there have been only limited studies on the relationship among mitophagy, ferroptosis and renal fibrosis. In this paper, we review the mechanisms of mitophagy, and describe how ferroptosis and mitophagy are related to renal fibrosis in an effort to identify potential novel targets for the treatment of renal fibrosis.

Involvement of NADPH oxidases in the Na/K‑ATPase/Src/ROS oxidant amplification loop in renal fibrosis

The Na/K‑ATPase/Src complex is reportedly able to affect reactive oxygen species (ROS) amplification. However, it has remained elusive whether NADPH oxidases (NOXs) are involved in this oxidant amplification loop in renal fibrosis. To test this hypothesis, interactions between oxidative features and Na/K‑ATPase/Src activation were examined in a mouse model of unilateral urethral obstruction (UUO)‑induced experimental renal fibrosis. Both 1‑tert‑butyl‑3‑(4‑chlorophenyl)‑1H‑pyrazolo[3,4‑d]pyrimidin‑4‑amine (PP2) and apocynin significantly attenuated the development of UUO‑induced renal fibrosis. Apocynin administration attenuated the expression of NOXs and oxidative markers (e.g., nuclear factor erythroid 2‑related factor 2, heme oxygenase‑1,4‑hydroxynonenal and 3‑nitrotyrosine); it also partially restored Na/K‑ATPase expression and inhibited the activation of the Src/ERK cascade. Furthermore, administration of PP2 after UUO induction partially reversed the upregulation of NOX2, NOX4 and oxidative markers, while inhibiting the activation of the Src/ERK cascade. Complementary experiments in LLC‑PK1 cells corroborated the in vivo observations. Inhibition of NOX2 by RNA interference attenuated ouabain‑induced oxidative stress, ERK activation and E‑cadherin downregulation. Thus, it is indicated that NOXs are major contributors to ROS production in the Na/K‑ATPase/Src/ROS oxidative amplification loop, which is involved in renal fibrosis. The disruption of this vicious feed‑forward loop between NOXs/ROS and redox‑regulated Na/K‑ATPase/Src may have therapeutic applicability for renal fibrosis disorders.

FOSL2 participates in renal fibrosis via SGK1-mediated epithelial-mesenchymal transition of proximal tubular epithelial cells

Background

Fos-related antigen 2 (FOSL2) plays a facilitative role in fibrotic disease; however, its role in renal fibrosis remains unclear. This study aimed to clarify the role and underlying mechanisms of FOSL2 in renal fibrosis.

Methods

Upregulated genes in unilateral ureteral obstruction (UUO)-injured kidneys were screened in Gene Expression Omnibus (GEO) databases, and overlapping genes were identified using Venn diagram software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed for these genes. The UUO-induced mouse model and transforming growth factor-β1 (TGF-β1)-induced cell model were used for the in vivo and in vitro studies.

Results

A total of 43 commonly upregulated genes were identified. GO and KEGG pathway analyses indicated that FOSL2 may be involved in fibrosis. Furthermore, FOSL2 was confirmed to be upregulated in UUO-injured kidneys and TGF-β1-induced cells. Knockdown of FOSL2 ameliorated interstitial fibrosis, extracellular matrix deposition, and epithelial-mesenchymal transition via the downregulation of fibronectin, α-smooth muscle actin (α-SMA), collagen type I (Col1a1 and Col1a2), and Col5a1 and upregulation of E-cadherin. Bioinformatics analysis revealed that serum/glucocorticoid regulated kinase 1 (SGK1) may be regulated by FOSL2 and involved in renal fibrosis. Further experiments confirmed that TGF-β1 enhanced SGK1 expression and transcription, which were reversed by FOSL2 silencing. Moreover, FOSL2 was bound to the SGK1 promoter, and SGK1 overexpression reversed the effects of FOSL2 silencing in TGF-β1-induced cells.

Conclusion

FOSL2 plays an essential role in promoting renal fibrosis in an SGK1-dependent manner, and targeting the FOSL2/SGK1 signaling axis may offer a potential strategy for the treatment of renal fibrosis.

Tamoxifen associated to the conservative CKD treatment promoted additional antifibrotic effects on experimental hypertensive nephrosclerosis

CKD progression depends on the activation of an intricate set of hemodynamic and inflammatory mechanisms, promoting renal leukocyte infiltration, inflammation and fibrosis, leading to renal function loss. There are currently no specific drugs to detain renal fibrogenesis, which is a common end-point for different nephropathies. Clinical therapy for CKD is mostly based on the management of hypertension and proteinuria, partially achieved with renin-angiotensin-aldosterone system (RAAS) blockers, and the control of inflammation by immunosuppressive drugs. The aim of the present study was to verify if the administration of tamoxifen (TAM), an estrogen receptor modulator, clinically employed in the treatment of breast cancer and predicted to exert antifibrotic effects, would promote additional benefits when associated to a currently used therapeutic scheme for the conservative management of experimental CKD. Wistar rats underwent the NAME model of hypertensive nephrosclerosis, obtained by daily oral administration of a nitric oxide synthesis inhibitor, associated to dietary sodium overload. The therapeutic association of TAM to losartan (LOS), and mofetil mycophenolate (MMF) effectively reduced the severe hypertension, marked albuminuria and glomerular damage exhibited by NAME animals. Moreover, the association also succeeded in limiting renal inflammation in this model, and promoted further reduction of ECM interstitial accumulation and renal fibrosis, compared to the monotherapies. According to our results, the association of TAM to the currently used conservative treatment of CKD added significant antifibrotic effects both in vivo and in vitro, and may represent an alternative to slow the progression of chronic nephropathy.

Psoralen Alleviates Renal Fibrosis by Attenuating Inflammasome-Dependent NLRP3 Activation and Epithelial-Mesenchymal Transition in a Mouse Unilateral Ureteral Obstruction Model

The role of psoralen (PS), a major active component extracted from Psoralea corylifolia L. seed, in renal fibrosis is still unclear. Thus, the objective of this study was to evaluate the effects of PS on the development and progression of renal fibrosis induced by unilateral ureteral obstruction (UUO) in a mouse model. Mice were divided into four groups: PS (20 mg/kg, i.g., n = 5), PS + sham (n = 5), UUO (n = 10), and PS + UUO (n = 10). PS was intragastrically administered 24 h before UUO and continued afterwards for 7 days. All mice were killed 7 days post UUO. Severe tubular atrophy, tubular injury, and tubulointerstitial fibrosis (TIF) were significantly developed in UUO mice. A higher expression of transforming growth factor-β1 (TGF-β1) was accompanied by elevated levels of α-smooth muscle actin (α-SMA) and phosphorylated Smad2/3 (pSmad2/3) at 7 days post UUO. However, PS treatment reduced tubular injury, interstitial fibrosis, and the expression levels of TGF-β1, α-SMA, and pSmad2/3. Furthermore, the levels of macrophages (represented by F4/80 positive cells) and the inflammasome, reflected by inflammasome markers such as nucleotide-binding and oligomerization domain-like receptors protein 3 (NLRP3) and cleaved caspase1 (cCASP-1), were significantly decreased by PS treatment. These results suggest that PS merits further exploration as a therapeutic agent in the management of chronic kidney disease (CKD).

Learning more from the inter-rater reliability of interstitial fibrosis assessment beyond just a statistic

Interstitial fibrosis assessment by renal pathologists lacks good agreement, and we aimed to investigate its hidden properties and infer possible clinical impact. Fifty kidney biopsies were assessed by 9 renal pathologists and evaluated by intraclass correlation coefficients (ICCs) and kappa statistics. Probabilities of pathologists' assessments that would deviate far from true values were derived from quadratic regression and multilayer perceptron nonlinear regression. Likely causes of variation in interstitial fibrosis assessment were investigated. Possible misclassification rates were inferred on reported large cohorts. We found inter-rater reliabilities ranged from poor to good (ICCs 0.48 to 0.90), and pathologists' assessments had the worst agreements when the extent of interstitial fibrosis was moderate. 33.5% of pathologists' assessments were expected to deviate far from the true values. Variation in interstitial fibrosis assessment was found to be correlated with variation in interstitial inflammation assessment (r2 = 32.1%). Taking IgA nephropathy as an example, the Oxford T scores for interstitial fibrosis were expected to be misclassified in 21.9% of patients. This study demonstrated the complexity of the inter-rater reliability of interstitial fibrosis assessment, and our proposed approaches discovered previously unknown properties in pathologists' practice and inferred a possible clinical impact on patients.

Systemic Mutation of Ncf1 Ameliorates Obstruction-Induced Renal Fibrosis While Macrophage-Rescued NCF1 Further Alleviates Renal Fibrosis

Aims: NCF1, a subunit of the NADPH oxidase 2 (NOX2), first described the expression in neutrophils and macrophages and participated in the pathogenesis from various systems. However, there are controversial findings on the role of NCF1 in different kinds of kidney diseases. In this study, we aim to pinpoint the specific role of NCF1 in the progression of renal fibrosis induced by obstruction. Results: In this study, NCF1 expression was upregulated in kidney biopsies of chronic kidney disease patients. The expression level of all subunits of the NOX2 complex was also significantly increased in the unilateral ureteral obstruction (UUO) kidney. Then, we used wild-type mice and Ncf1 mutant mice (Ncf1m1j mice) to perform UUO-induced renal fibrosis. Results demonstrated that Ncf1m1j mice exhibited mild renal fibrosis but increased macrophages count and CD11b+Ly6Chi macrophage proportion. Next, we compared the renal fibrosis degree between Ncf1m1j mice and Ncf1 macrophage-rescued mice (Ncf1m1j.Ncf1Tg-CD68 mice). We found that rescuing NCF1 expression in macrophages further alleviated renal fibrosis and decreased macrophage infiltration in the UUO kidney. In addition, flow cytometry data showed fewer CD11b+Ly6Chi macrophages in the kidney of the Ncf1m1j.Ncf1Tg-CD68 group than the Ncf1m1j group. Innovation: We first used the Ncf1m1j mice and Ncf1m1j.Ncf1Tg-CD68 mice to detect the role of NCF1 in the pathological process of renal fibrosis induced by obstruction. Also, we found that NCF1 expressed in different cell types exerts opposing effects on obstructive nephropathy. Conclusion: Taken together, our findings support that systemic mutation of Ncf1 ameliorates renal fibrosis induced by obstruction, and rescuing NCF1 in macrophages further alleviates renal fibrosis.

Global research trends in unilateral ureteral obstruction-induced renal fibrosis: A bibliometric and visualized study

BACKGROUND

Renal fibrosis is considered the pathway from almost all chronic kidney diseases (CKD) to end-stage renal diseases. The unilateral ureteral obstruction (UUO) model is a well-established experimental animal model to simulate renal fibrosis associated with obstructive nephropathy in an accelerated manner. In this study, in order to understand the development trends of research on UUO-induced renal fibrosis between 2005 and 2022 and predict prospects, we conducted a comprehensive bibliometric and visualized study using Web of Science (WoS).

METHODS

The articles regarding UUO-induced renal fibrosis were culled from the "Core Collection" of the WoS database. VOSviewer software and the R-Bibliometrix Package were used in visual analysis of countries/regions, journals, authors, keywords, institutions, and highly cited articles in this field.

RESULTS

The number of articles regarding UUO-induced renal fibrosis has obviously increased annually. China had the largest number of publications in this field. The most frequently used keywords were "inflammation," "transforming growth factor-beta1," "oxigative stress," "smad3," "beta-catenin," and "autophagy." Am J Physiol-Renal was the leading journal. The most highly influential documents were published by Higgins DF and his colleagues, with 46 local citations and 749 global citations. The leading institution was Nanjing Medical University. Furthermore, Zhang Y. was the author who contributed most to this field.

CONCLUSION

Our results suggest that the molecular mechanism of UUO-induced renal fibrosis remains a research hot topic, especially on the inflammatory response and oxidative stress, and international cooperation is expected to expand and deepen in the future.

Sex-specific epigenetic programming in renal fibrosis and inflammation

The growing prevalence of hypertension, heart disease, diabetes, and obesity along with an aging population, is leading to higher incidence of renal diseases in the society. Chronic kidney disease (CKD) is characterized mainly by persistent inflammation, fibrosis, and gradual loss of renal function leading to renal failure. Sex is a known contributor to the differences in incidence and progression of CKD. Epigenetic programming is an essential regulator of renal physiology and is critically involved in the pathophysiology of renal injury and fibrosis. Epigenetic signaling integrates intrinsic and extrinsic signals onto the genome, and various environmental and hormonal stimuli, including sex hormones, which regulate gene expression and downstream cellular responses. The most extensively studied epigenetic alterations that play a critical role in renal damage include histone modifications and DNA methylation. Notably, these epigenetic alterations are reversible, making them candidates for potential therapeutic targets for the treatment of renal diseases. Here, we will summarize the current knowledge on sex-differences in epigenetic modulation of renal fibrosis and inflammation and highlight some possible epigenetic therapeutic strategies for CKD treatment.

T Follicular Helper Cells in Tertiary Lymphoid Structure Contribute to Renal Fibrosis by IL-21

Tertiary lymphoid structure (TLS) represents lymphocyte clusters in non-lymphoid organs. The formation and maintenance of TLS are dependent on follicular helper T (TFH) cells. However, the role of TFH cells during renal TLS formation and the renal fibrotic process has not been comprehensively elucidated in chronic kidney disease. Here, we detected the circulating TFH cells from 57 IgAN patients and found that the frequency of TFH cells was increased in IgA nephropathy patients with renal TLS and also increased in renal tissues from the ischemic-reperfusion-injury (IRI)-induced TLS model. The inducible T-cell co-stimulator (ICOS) is one of the surface marker molecules of TFH. Remarkably, the application of an ICOS-neutralizing antibody effectively prevented the upregulation of TFH cells and expression of its canonical functional mediator IL-21, and also reduced renal TLS formation and renal fibrosis in IRI mice in vivo. In the study of this mechanism, we found that recombinant IL-21 could directly promote renal fibrosis and the expression of p65. Furthermore, BAY 11-7085, a p65 selective inhibitor, could effectively alleviate the profibrotic effect induced by IL-21 stimulation. Our results together suggested that TFH cells contribute to TLS formation and renal fibrosis by IL-21. Targeting the ICOS-signaling pathway network could reduce TFH cell infiltration and alleviate renal fibrosis.