Development Of Renal Fibrosis Research Articles

PRR promotes hypertensive renal injury by activating Wnt/β-catenin signaling and inflammation infiltration in mice

Hypertension stands out as a substantial independent risk factor in the progression of chronic kidney disease; however, the exact pathological mechanisms remain elusive. Our preliminary studies find that Wnt/β-catenin control renin-angiotensin system (RAS) expression, thus playing an important role in the pathogenesis of hypertension and renal fibrosis. As an integral component of the RAS, the (pro)renin receptor (PRR) plays a crucial role in the activation of the RAS and hypertension. Recent studies suggest a reciprocal relationship between PRR and Wnt/β-catenin signaling, potentially contributing to hypertensive renal fibrosis development. To assess the role of PRR in mediating hypertensive nephropathy, we manipulated this signaling by over expression of PRR ligand or blockade of PRR by siPRR. In vivo, PRR induction promoted hypertension, proteinuria, renal fibrosis, inflammatory response and β-catenin activation in Ang II induced hypertension mice. Conversely, blockade of PRR inhibited Ang II mediated hypertension, renal fibrosis and inflammation. In vitro, PRR over expression renal tubular cells exacerbated the Ang II induced fibrotic response and inflammation. Moreover, PRR was upregulated in hypertensive nephropathy patients, and correlated with renal function and renal fibrosis. These results indicate that PRR interact with Wnt/β-catenin signaling promote the progression of hypertensive nephropathy. PRR could be served as a biomarker for the diagnosis and treatment of hypertensive renal fibrosis.

Macrophage-Induced Pro-Fibrotic Gene Expression in Tubular Cells after Ischemia/Reperfusion Is Paralleled but Not Directly Mediated by C5a/C5aR1 Signaling.

Ischemia/reperfusion (I/R) is inevitable during kidney transplantation and causes acute kidney injury (AKI), which affects immediate outcome and leads to chronic changes such as fibrotic remodeling of the graft. We investigated pro-fibrotic signaling after I/R, focusing on the complement component and receptor C5a/C5aR1 and macrophage/tubule crosstalk. Male Dark Agouti rats were subjected to I/R and their kidneys were harvested 10 min, 6 h, 24 h, 3 days, 5 days and 8 weeks after reperfusion. The development of renal fibrosis was assessed by the detection of Vimentin (VIM), α-smooth muscle actin (α-SMA) and collagen by immunohistochemistry and Sirius Red staining, respectively. The characterization of C5a/C5aR1 activity and C5aR1+ cells was performed by multiplex mRNA analysis, ELISA, immunofluorescence flow cytometry and in situ hybridization in animal models and cell culture analyses. In the cell culture experiments, we focused on macrophage/tubule cell crosstalk in co-culture experiments and mimicked in vivo conditions by hypoxia/reoxygenation and supplementation with C5a. Already 6-24 h after the induction of I/R in the rat model, C5a concentration in the plasma was significantly increased compared to the control. The matrix components VIM and α-SMA peaked on day 5 and declined after 8 weeks, when an increase in collagen was detected using Sirius Red. In contrast to early I/R-induced C5a activation, renal C5ar1 expression was maximal at day 5 and C5 expression increased until week 8, indicating that the renal upregulation of expression is not required for early complement activation. C5aR1 mRNA was detected in neutrophils and macrophages, but not in proximal tubular cells in the injured kidneys. The macrophage/tubular cell co-culture experiments showed that macrophages were mainly responsible for the increased expression of fibrosis-associated genes in tubule cells (ACTA2, VIM, SNAI1, TGFB1 and FGF-2), and hypoxia/reoxygenation had a partially enhancing effect. A direct pro-fibrotic effect of C5a was not observed. Increased TGF-ß levels were dependent on the differentiation of macrophages to the M2 subtype. In conclusion, the early activation of mesenchymal markers in tubular epithelial cells leads to long-term fibrotic remodeling characterized by VIM expression and driven by TGF-ß-dependent macrophage/tubular crosstalk. The chemoattractive properties of complement C5a may contribute to the recruitment of pro-fibrotic macrophages.

Enhanced eNOS/nitric oxide production by nebivolol interferes with TGF-β1/Smad3 signaling and collagen I deposition in the kidney after prolonged tacrolimus administration

AimsTacrolimus is an effective immunosuppressant commonly used post-transplantation and in certain autoimmune diseases. However, its long-term administration is associated with renal fibrosis through transforming growth factor-beta/suppressor of mother against decapentaplegic (TGF-β/Smad) signaling that could be partly attributed to endothelial dysfunction alongside decreased nitric oxide (NO) release. Our study aimed to investigate the prospective renal anti-fibrotic effect of enhanced NO production by nebivolol against tacrolimus-stimulated TGF-β1/Smad3 signaling. Materials and methodsTo illustrate the proposed mechanism of nebivolol, Nω-nitro-L-arginine methyl ester (L-NAME); nitric oxide synthase inhibitor; was co-administered with nebivolol. Rats were treated for 30 days as control, tacrolimus, tacrolimus/nebivolol, tacrolimus/L-NAME, and tacrolimus/nebivolol/L-NAME groups. Key findingsOur results revealed that renal NO content was reduced in tacrolimus-treated rats, while treatment with tacrolimus/nebivolol enhanced NO content via up-regulated endothelial nitric oxide synthase (eNOS), but down-regulated inducible nitric oxide synthase (iNOS) expression. That participated in the inhibition of TGF-β1/Smad3 signaling induced by tacrolimus, where the addition of L-NAME abolished the defensive effects of nebivolol. Subsequently, the deposition of collagen I and alpha-smooth muscle actin (α-SMA) was retarded by nebivolol, emphasized by reduced Masson's trichrome staining. In accordance, there was a strong negative correlation between eNOS and both TGF-β1 and collagen I protein expression. The protective effects of nebivolol were further confirmed by the improvement in kidney function biomarkers and histological features. SignificanceIt can be suggested that treatment with nebivolol along with tacrolimus could effectively suppress renal TGF-β1/Smad3 fibrotic signaling via the enhancement of endothelial NO production, thus curbing renal fibrosis development.

Chlorogenic acid alleviates renal fibrosis by reducing lipid accumulation in diabetic kidney disease through suppressing the Notch1 and Stat3 signaling pathway

Aims Abnormal renal lipid metabolism causes renal lipid deposition, which leads to the development of renal fibrosis in diabetic kidney disease (DKD). The aim of this study was to investigate the effect and mechanism of chlorogenic acid (CA) on reducing renal lipid accumulation and improving DKD renal fibrosis. Methods This study evaluated the effects of CA on renal fibrosis, lipid deposition and lipid metabolism by constructing in vitro and in vivo models of DKD, and detected the improvement of Notch1 and Stat3 signaling pathways. Molecular docking was used to predict the binding between CA and the extracellular domain NRR1 of Notch1 protein. Results In vitro studies have shown that CA decreased the expression of Fibronectin, α-smooth muscle actin (α-SMA), p-smad3/smad3, alleviated lipid deposition, promoted the expression of carnitine palmitoyl transferase 1 A (CPT1A), and inhibited the expression of cholesterol regulatory element binding protein 1c (SREBP1c). The expression of Notch1, Cleaved Notch1, Hes1, and p-stat3/stat3 were inhibited. These results suggested that CA might reduce intercellular lipid deposition in human kidney cells (HK2) by inhibiting Notch1 and stat3 signaling pathways, thereby improving fibrosis. Further, in vivo studies demonstrated that CA improved renal fibrosis and renal lipid deposition in DKD mice by inhibiting Notch1 and stat3 signaling pathways. Finally, molecular docking experiments showed that the binding energy of CA and NRR1 was −6.6 kcal/mol, which preliminarily predicted the possible action of CA on Notch1 extracellular domain NRR1. Conclusion CA reduces renal lipid accumulation and improves DKD renal fibrosis by inhibiting Notch1 and stat3 signaling pathways.

Lacticaseibacillus rhamnosus Fmb14 ameliorates hyperuricemia-induced hepatocyte pyroptosis via NLRP3 inflammasome cascade inhibition

Hyperuricemia is a high-risk factor for the development of gout and renal fibrosis, but the adverse effects of hyperuricemia on the liver have been seriously neglected. This research investigated the ameliorating effect of Lacticaseibacillus rhamnosus Fmb14 on hyperuricemia induced liver dysfunction both in vitro and in vivo. Cell free extracts of high dose L. rhamnosus Fmb14 treatment reduced the death rate of HepG2 cell lines from 24.1 % to 14.9 % by inhibiting NLRP3 recruitment, which was mainly activated by reactive oxygen species release and mitochondrial membrane potential disorder. In purine dietary induced hyperuricemia (PDIH) mice model, liver oedema and pyroptosis were ameliorated after L. rhamnosus Fmb14 administration through downregulating the expression levels of NLRP3, caspase-1 and gasdermin-D from 1.61 to 0.86, 3.15 to 1.01 and 5.63 to 2.02, respectively. L. rhamnosus Fmb14 administration restored mitochondrial inner membrane protein (MPV17) and connexin 43 from 2.83 and 0.73 to 0.80 and 0.98 respectively in PDIH mice, indicating that dysbiosis of mitochondrial membrane potential was restored in liver. Intriguingly, PDIH pyroptosis stimulates the process of apoptosis, which leads to severe leakage of hepatocytes, and both of pyroptosis and apoptosis were decreased after L. rhamnosus Fmb14 treatment. Therefore, L. rhamnosus Fmb14 is a promising biological resource to maintain homeostasis of the liver in hyperuricemia and the prevention of subsequent complications.

Exosomes on the development and progression of renal fibrosis.

Renal fibrosis is a prevalent pathological alteration that occurs throughout the progression of primary and secondary renal disorders towards end-stage renal disease. As a complex and irreversible pathophysiological phenomenon, it includes a sequence of intricate regulatory processes at the molecular and cellular levels. Exosomes are a distinct category of extracellular vesicles that play a crucial role in facilitating intercellular communication. Multiple pathways are regulated by exosomes produced by various cell types, including tubular epithelial cells and mesenchymal stem cells, in the context of renal fibrosis. Furthermore, research has shown that exosomes present in bodily fluids, including urine and blood, may be indicators of renal fibrosis. However, the regulatory mechanism of exosomes in renal fibrosis has not been fully elucidated. This article reviewed and analysed the various mechanisms by which exosomes regulate renal fibrosis, which may provide new ideas for further study of the pathophysiological process of renal fibrosis and targeted treatment of renal fibrosis with exosomes.

The Participation of Ferroptosis in Fibrosis of the Heart and Kidney Tissues in Dahl Salt-Sensitive Hypertensive Rats.

Salt-sensitive hypertension is often more prone to induce damage to target organs such as the heart and kidneys. Abundant recent studies have demonstrated a close association between ferroptosis and cardiovascular diseases. Therefore, we hypothesize that ferroptosis may be closely associated with organ damage in salt-sensitive hypertension. This study aimed to investigate whether ferroptosis is involved in the occurrence and development of myocardial fibrosis and renal fibrosis in salt-sensitive hypertensive rats. Ten 7-week-old male Dahl salt-sensitive (Dahl-SS) rats were adaptively fed for 1 week, then randomly divided into two groups and fed either a normal diet (0.3% NaCl, normal diet group) or a high-salt diet (8% NaCl, high-salt diet group) for 8 weeks. Blood pressure of the rats was observed, and analysis of the hearts and kidneys of Dahl-SS rats was conducted via hematoxylin-eosin (HE) staining, Masson staining, Prussian blue staining, transmission electron microscopy, tissue iron content detection, malondialdehyde content detection, immunofluorescence, and Western blot. Compared to the normal diet group, rats in the high-salt diet group had increases in systolic blood pressure and diastolic blood pressure (P < 0.05); collagen fiber accumulation was observed in the heart and kidney tissues (P < 0.01), accompanied by alterations in mitochondrial ultrastructure, reduced mitochondrial volume, and increased density of the mitochondrial double membrane. Additionally, there were significant increases in both iron content and malondialdehyde levels (P < 0.05). Immunofluorescence and Western blot results both indicated significant downregulation (P < 0.05) of xCT and GPX4 proteins associated with ferroptosis in the high-salt diet group. Ferroptosis is involved in the damage and fibrosis of the heart and kidney tissues in salt-sensitive hypertensive rats.

#2385 Inhibition of histone lysine demethylases 5 attenuates acute kidney injury but not acute kidney disease or chronic kidney disease

Abstract Background and Aims The histone lysine demethylases 5 (KDM5) are members of the family of Jumonji C domain-containing histone demethylases and catalyze the removal of di- and tri-methyl moieties from the fourth lysine of histone 3 (H3K4me2/3). It has been reported that the KDM5 family mediates a range of physiological and pathological events including cell differentiation, motility, senescence and epithelial-mesenchymal transition (EMT) via activating or repressing transcription in demethylase-dependent or independent manners in both homeostasis and disease. This study investigated the potential role of KDM5 in the development and progression of renal fibrosis in acute kidney injury (AKI), chronic kidney disease (CKD) or AKI to CKD transition (acute kidney disease, AKD). Method We evaluated therapeutic effects of KDM5 inhibition in AKI model of unilateral nephrectomy plus contralateral ischemia-reperfusion (IR) injury, AKI to CKD transition model of unilateral IR injury plus removal of contralateral uninjured kidney after 8 days of IR injury, and CKD model of unilateral ureteral obstruction (UUO) in mice. Results KDM5 C70 inhibitor prevented the increase of blood urea nitrogen and positive areas of trichrome, Sirius red, F4/80 and α-smooth muscle actin in injured kidneys 7 days after IR injury. Significant reductions in renal mRNA levels of pro-inflammatory cytokine/chemokine, EMT and pro-fibrotic markers (IL-1β, IL-6, TNF-α, CCL2, CCL3, GM-CSF, MMP9, fibronectin, vimentin, TGF-β1, COL4A1) were also observed with attenuated mRNA levels of KDM5a-c. In addition, renal protein levels of antioxidants such as catalase, SOD1 and SOD2 were increased in injured kidneys of KDM5 inhibitor-treated mice. However, parameters of renal fibrosis and inflammation were similar between mice without and with KDM5 inhibitor in both AKD and CKD models. Conclusion These data demonstrate that inhibition of KDM5 could prevent renal inflammation and fibrosis after acute and severe IR injury. The activation of KDM5 might be an early step in the development of renal fibrosis after AKI insult.

Emodin improves renal fibrosis in chronic kidney disease by regulating mitochondrial homeostasis through the mediation of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α).

Chronic kidney disease (CKD) is a leading public health issue associated with high morbidity worldwide. However, there are only a few effective therapeutic strategies for CKD. Emodin, an anthraquinone compound from rhubarb, can inhibit fibrosis in tissues and cells. Our study aims to investigate the antifibrotic effect of emodin and the underlying molecular mechanism. A unilateral ureteral obstruction (UUO)-induced rat model was established to evaluate the effect of emodin on renal fibrosis development. Hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry staining were performed to analyze histopathological changes and fibrotic features after emodin treatment. Subsequently, a transforming growth factor-beta 1 (TGF-β1)-induced cell model was used to assess the inhibition of emodin on cell fibrosis in vitro. Furthermore, Western blot analysis and real-time quantitative reverse transcription-polymerase chain reaction were performed to validate the regulatory mechanism of emodin on renal fibrosis progression. As a result, emodin significantly improved histopathological abnormalities in rats with UUO. The expression of fibrosis biomarkers and mitochondrial biogenesis-related proteins also decreased after emodin treatment. Moreover, emodin blocked TGF-β1-induced fibrotic phenotype, lipid accumulation, and mitochondrial homeostasis in NRK-52E cells. Conversely, peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α) silencing significantly reversed these features in emodin-treated cells. Collectively, emodin plays an important role in regulating PGC-1α-mediated mitochondria function and energy homeostasis. This indicates that emodin exhibits great inhibition against renal fibrosis and acts as a promising inhibitor of CKD.

RISK FACTORS AND CLINICAL CORRELATIONS OF URINARY TGF-Β1 IN CHILDREN WITH JUVENILE IDIOPATHIC ARTHRITIS AND EARLY KIDNEY FIBROSIS

The course of juvenile idiopathic arthritis (JIA) is associated with a long-term infl ammatory process and the use of nonsteroidal anti-infl ammatory drugs (NSAIDs), which can cause nephrotoxicity with fi brotic kidney damage in patients with JIA. Regardless of the etiology of joint damage, prolonged infl ammation promotes the progression of fi brosis, and renal fi brosis is the fi nal common stage of chronic kidney disease (CKD). Kidney biopsy, which is invasive, risky and underutilized, is generally considered the only clinical method to detect fi brosis. Over the past decade, some progress has been made in the search for minimally invasive biomarkers of early kidney fi brosis, with transforming growth factor-β1 (TGF-β1) playing a key role in the progression of kidney fi brosis, but the signifi cance of TGF-β1 in children with JIA is unknown.Material and Methods: 80 children with JIA were examined. Urinary TGF-β1 levels were determined using a TGF-β1 ELISA kit(DRG International, Inc., Germany, EIA-1864) according to the manufacturer’s instructions. Methods of variation statistics were used. Informed consent was obtained from all patients. The study has a positive conclusion of the Commission on Biomedical Ethics of Dnipro State Medical University (Minutes of the meeting of the Commission No. 12 dated December 19, 2002), which decided that the scientifi c research can be considered in accordance with generally accepted moral standards, the requirements of respecting the rights, interests and personal dignity of study participants, bioethical standards for work with pediatric patients. There is no risk to the research subjects in the performance of the work. The legal representatives of the children involved in the research are informed about all aspects related to the purpose, objectives, methods and expected benefi ts of the research. Laboratory and instrumental research methods are generally accepted; the drugs to be used are approved for use. No human experiments were performed.Methods of variation statistics were used. Statistical analysis was performed using the STATISTICA 6.1 software package(StatSoft Inc., serial no. AGAR909E415822FA). The work was carried out as part of the research work of the Department of Propaedeutic of Childhood Diseases and Pediatrics 2 of the Dnipro State Medical University «Development of criteria for early diagnosis and prediction of comorbid kidney damage in children with somatic and infectious diseases» (state registration No. 0119U100932, implementation period 01.2019-12.2023).Results. The mean TGF-β1 level in our study was 20.26±16.34 (14.02, 12.5-17.98) pg/ml. Polyarthritis almost quadrupledthe probability of pathological changes in TGF-β1. The overwhelming majority of children with elevated TGF-β1 suff ered from polyarthritis (80.0 %) – one and a half times more often than those with relatively normal TGF-β1 concentration, p&lt;0.04.If the active stage of the disease lasted at least 4 years, the probability of elevated TGF-β1 increased more than sixfold. Thetendency of signifi cant nephrotoxic eff ect of prolonged active JIA was confi rmed by the results of correlation analysis, according to which, in general, the duration of active JIA was directly related to the increase of TGF-β1 (ρ=0.38, p&lt;0.001), and the duration of remission and the total duration of JIA had no signifi cant correlation with it (ρ= –0.19 and ρ=0.18, respectively, p&gt;0.05). The direct dependence of elevated urinary TGF-β1 levels on clinical features such as polyarthritis and the duration of the active phase of JIA has been demonstrated. These clinical features in children with JIA can be considered as risk factors for the development of early renal fi brosis. Against the background of elevated TGF-β1, a reduced GFR according to the Hoek formula (&lt;90 ml/min/1.73 m2) was found in 95 % of cases, i. e. the estimates of the functional state of the kidneys obtained by two diff erent methods were quite clearly the same. In the sample with TGF-β1&lt;17.98 pg/ml, 22.76 % of children received immunobiologic therapy, while in the sample to increase TGF-β1 – only 14.76 %. Immunobiological therapy reduced the risk of increasing this urinary marker by 5.5 times.Conclusions. Elevated levels of the TGF-β1 biomarker were found in 25 % of children with JIA. An association of early renalfi brosis with duration of active phase of JIA ≥ 4 years, increased ESR, polyarthritis, arterial hypertension, and dental carieswas observed. Elevated urinary TGF-β1 levels are associated with reduced eGFR and are observed in almost all children witheGFR&lt;90 ml/min/1.73 m2, confi rming the importance of early renal fi brosis in the development of renal dysfunction.

Arsenic exposure induced renal fibrosis via regulation of mitochondrial dynamics and the NLRP3-TGF-β1/SMAD signaling pathway.

Environmental arsenic exposure is one of the major global public health problems. Studies have shown that arsenic exposure can cause renal fibrosis, but the underlying mechanism is still unclear. Integrating the in vivo and in vitro models, this study investigated the potential molecular pathways for arsenic-induced renal fibrosis. In this study, SD rats were treated with 0, 5, 25, 50, and 100 mg/L NaAsO2 for 8 weeks via drinking water, and HK2 cells were treated with different doses of NaAsO2 for 48 h. The in vivo results showed that arsenic content in the rats' kidneys increased as the dose increased. Body weight decreased and kidney coefficient increased at 100 mg/L. As a response to the elevated NaAsO2 dose, inflammatory cell infiltration, renal tubular injury, glomerular atrophy, tubulointerstitial hemorrhage, and fibrosis became more obvious indicated by HE and Masson staining. The kidney transcriptome profiles further supported the protein-protein interactions involved in NaAsO2-induced renal fibrosis. The in vivo results, in together with the in vitro experiments, have revealed that exposure to NaAsO2 disturbed mitochondrial dynamics, promoted mitophagy, activated inflammation and the TGF-β1/SMAD signaling pathway, and finally resulted in fibrosis. In summary, arsenic exposure contributed to renal fibrosis via regulating the mitochondrial dynamics and the NLRP3-TGF-β1/SMAD signaling axis. This study presented an adverse outcome pathway for the development of renal fibrosis due to arsenic exposure through drinking water.

Natural intestinal metabolite xylitol reduces BRD4 levels to mitigate renal fibrosis.

Renal fibrosis is a typical pathological change from chronic kidney disease (CKD) to end-stage renal failure, which presents significant challenges in prevention and treatment. The progression of renal fibrosis is closely associated with the "gut-kidney axis," therefore, although clinical intervention to modulate the "gut-kidney axis" imbalance associated with renal fibrosis brings hope for its treatment. In this study, we first identified the close relationship between renal fibrosis development and the intestinal microenvironment through fecal microtransplantation and non-absorbable antibiotics experiments. Then, we analyzed the specific connection between the intestinal microenvironment and renal fibrosis using microbiomics and metabolomics, screening for the differential intestinal metabolite. Potential metabolite action targets were initially identified through network simulation of molecular docking and further verified by molecular biology experiment. We used flow cytometry, TUNEL apoptosis staining, immunohistochemistry, and Western blotting to assess renal injury and fibrosis extent, exploring the potential role of gut microbial metabolite in renal fibrosis development. We discovered that CKD-triggered alterations in the intestinal microenvironment exacerbate renal injury and fibrosis. When metabolomic analysis was combined with experiments invivo, we found that the differential metabolite xylitol delays renal injury and fibrosis development. We further validated this hypothesis at the cellular level. Mechanically, bromodomain-containing protein 4 (BRD4) protein exhibits strong binding with xylitol, and xylitol alleviates renal fibrosis by inhibiting BRD4 and its downstream transforming growth factor-β (TGF-β) pathway. In summary, our findings suggest that the natural intestinal metabolite xylitol mitigates renal fibrosis by inhibiting the BRD4-regulated TGF-β pathway.

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

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

Lymphatic System and the Kidney: From Lymphangiogenesis to Renal Inflammation and Fibrosis Development.

The lymphatic kidney system plays a crucial role in managing interstitial fluid removal, regulating fluid balance, and tuning immune response. It also assists in the reabsorption of proteins, electrolytes, cytokines, growth factors, and immune cells. Pathological conditions, including tissue damage, excessive interstitial fluid, high blood glucose levels, and inflammation, can initiate lymphangiogenesis-the formation of new lymphatic vessels. This process is associated with various kidney diseases, including polycystic kidney disease, hypertension, ultrafiltration challenges, and complications post-organ transplantation. Although lymphangiogenesis has beneficial effects in removing excess fluid and immune cells, it may also contribute to inflammation and fibrosis within the kidneys. In this review, we aim to discuss the biology of the lymphatic system, from its development and function to its response to disease stimuli, with an emphasis on renal pathophysiology. Furthermore, we explore how innovative treatments targeting the lymphatic system could potentially enhance the management of kidney diseases.

RIPK3 Expression in Fibroblasts in an in vivo and in vitro Skin Wound Model: A Controversial Result.

One of the major problems of regenerative medicine is the development of hypertrophic scars and keloids. The protein kinase RIPK3 is involved in necroptosis; however, recent evidence indicates that it also has non-canonical functions, including its involvement in the development of renal fibrosis. The aim of our work was to study the expression of RIPK3 in mouse and human skin models of fibrotic processes. A subpopulation of RIPK3+Vim+ cells was found in both human keloid and a mouse wound, with the cell number being significantly greater in the mouse wound bed compared to healthy skin. Real-time polymerase chain reaction (RT-PCR) detected expression of the Ripk3 and fibroblast biomarkers Acta2, Fap, Col1a1, and Fn1 in the cells isolated from the wound bed, indicating that RIPK3 can be expressed by wound bed fibroblasts. An analysis of the human fibroblasts stained with anti-RIPK3 antibodies demonstrated an increase in the fluorescence intensity in the presence of lipopolysaccharide (LPS) at concentrations of 5, 10, 25, 50, and 100 ng/ml and TGF-β at concentrations of 0.1, 1, 2, and 5 ng/ml compared to the control. At the same time, the expression levels of RIPK3 and fibroblast activation markers in the presence of TGF-β and LPS did not differ significantly from the control. It is possible that RIPK3 expression in wound fibroblasts is not directly associated with fibrotic processes, and that kinase plays a different, yet unknown role in wound healing. KEYWORDS scarring, keloid, skin, fibroblasts, cell culture, RIPK3.

The metabolic pathway regulation in kidney injury and repair.

Kidney injury and repair are accompanied by significant disruptions in metabolic pathways, leading to renal cell dysfunction and further contributing to the progression of renal pathology. This review outlines the complex involvement of various energy production pathways in glucose, lipid, amino acid, and ketone body metabolism within the kidney. We provide a comprehensive summary of the aberrant regulation of these metabolic pathways in kidney injury and repair. After acute kidney injury (AKI), there is notable mitochondrial damage and oxygen/nutrient deprivation, leading to reduced activity in glycolysis and mitochondrial bioenergetics. Additionally, disruptions occur in the pentose phosphate pathway (PPP), amino acid metabolism, and the supply of ketone bodies. The subsequent kidney repair phase is characterized by a metabolic shift toward glycolysis, along with decreased fatty acid β-oxidation and continued disturbances in amino acid metabolism. Furthermore, the impact of metabolism dysfunction on renal cell injury, regeneration, and the development of renal fibrosis is analyzed. Finally, we discuss the potential therapeutic strategies by targeting renal metabolic regulation to ameliorate kidney injury and fibrosis and promote kidney repair.

NSD2 modulates Drp1-mediated mitochondrial fission in chronic renal allograft interstitial fibrosis by methylating STAT1

Renal interstitial fibrosis/tubular atrophy (IF/TA) is a prominent pathological feature of chronic allograft dysfunction (CAD). Our previous study has demonstrated that epithelial-mesenchymal transition (EMT) plays a significant role in shaping the development of IF/TA. Nuclear SET domain (NSD2), a histone methyltransferase catalyzing methylation at lysine 36 of histone 3, is crucially involved in the development and progression of solid tumors. But its role in the development of renal allograft interstitial fibrosis has yet to be elucidated. Here, we characterize NSD2 as a crucial mediator in the mouse renal transplantation model in vivo and a model of tumor necrosis factor-α (TNF-α) stimulated-human renal tubular epithelial cells (HK-2) in vitro. Functionally, NSD2 knockdown inhibits EMT, dynamin-related protein 1 (Drp1)-mediated mitochondrial fission in mice. Conversely, NSD2 overexpression exacerbates fibrosis-associated phenotypes and mitochondrial fission in tubular cells. Mechanistically, tubular NSD2 aggravated the Drp-1 mediated mitochondrial fission via STAT1/ERK/PI3K/Akt signaling pathway in TNF-α-induced epithelial cell models. Momentously, mass spectrometry (MS) Analysis and site-directed mutagenesis assays revealed that NSD2 interacted with and induced Mono-methylation of STAT1 on K173, leading to its phosphorylation, IMB1-dependent nuclear translocation and subsequent influence on TNF-α-induced EMT and mitochondrial fission in NSD2-dependent manner. Collectively, these findings shed light on the mechanisms and suggest that targeting NSD2 could be a promising therapeutic approach to enhance tubular cell survival and alleviate interstitial fibrosis in renal allografts during CAD.

Protective effect of ischaemic preconditioning on acute and chronic renal damage following ischaemia reperfusion injury: characterisation of fibrosis development after inflammation resolution.

Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD) are increasingly recognised as one disease continuum, rather than distinct entities, and are associated with a huge burden to healthcare services. The leading cause of AKI worldwide is Ischaemia Reperfusion Injury (IRI), most commonly seen in clinical settings of sepsis-driven hypotension. Ischaemic Preconditioning (IPC) is a strategy aimed at reducing the deleterious effects of IRI. The objectives of this study were to demonstrate an efficacious in vivo model of Kidney IRI, and the protective influence of IPC in attenuating AKI and development of renal fibrosis. A rat model of bilateral kidney IRI was used: Male Lewis rats (n=84) were assigned to IRI, sham or IPC. In IRI, renal pedicles were clamped for 45 minutes. IPC groups underwent pulsatile IPC prior to IRI. Kidneys were retrieved at 24 hours, 48 hours, 7 days, 14 days and 28 days, and assessed histologically. IRI led to marked AKI (24-48 h) and renal fibrosis development by 28 days. IPC attenuated this damage, with 66% less fibrosis. Interestingly, at 14-days, the histological appearance of both IRI and IPC kidneys was rather similar, potentially representing an important transitional point at which kidneys commit to either fibrosis or recovery. This may provide a suitable inflexion point for introduction of novel anti-fibrotic therapies. In conclusion, we have characterised a model of kidney injury from acute to chronic phases, allowing detailed mechanistic understanding and which can be manipulated by effective treatment strategies such as IPC.

APC and ZBTB2 May Mediate M2 Macrophage Infiltration to Promote the Development of Renal Fibrosis: A Bioinformatics Analysis.

Background and Purpose: The continuous accumulation of M2 macrophages may potentially contribute to the development of kidney fibrosis in chronic kidney disease (CKD). The purpose of this study was to analyze the infiltration of M2 macrophages in uremic patients and to seek new strategies to slow down the progression of renal fibrosis. Methods: We conducted a comprehensive search for expression data pertaining to uremic samples within the Gene Expression Omnibus (GEO) database, encompassing the time frame from 2010 to 2022. Control and uremic differentially expressed genes (DEGs) were identified. Immune cell infiltration was investigated by CIBERSORT and modules associated with M2 macrophage infiltration were identified by weighted gene coexpression network analysis (WGCNA). Consistent genes were identified using the least absolute shrinkage and selection operator (LASSO) and selection and visualization of the most relevant features (SVM-RFE) methods to search for overlapping genes. Receiver operating characteristic (ROC) curves were examined for the diagnostic value of candidate genes. Quantitative real-time PCR (qPCR) examined the expression levels of candidate genes obtained from uremic patients in M2 macrophage. Results: A total of 1298 DEGs were identified within the GSE37171 dataset. Significant enrichment of DEGs was observed in 20 biological processes (BP), 19 cellular components (CC), 6 molecular functions (MF), and 70 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. CIBERSORT analysis observed a significant increase in B-cell memory, dendritic cell activation, M0, M1, M2, and plasma cell numbers in uremic samples. We identified the 10 most interrelated genes. In particular, adenomatous polyposis coli (APC) and zinc finger and BTB structural domain 2 (ZBTB2) were adversely associated with the infiltration of M2 macrophages. Importantly, the expression levels of APC and ZBTB2 were far lower in M2 macrophages from uremic patients than those in healthy individuals. Conclusion: The development of renal fibrosis may be the result of M2 macrophage infiltration promoted by APC and ZBTB2.

The Influence of Betulin Derivatives EB5 and ECH147 on the Expression of Selected TGFβ Superfamily Genes, TGFβ1, GDF15 and BMP2, in Renal Proximal Tubule Epithelial Cells.

Betulin derivatives are proposed to serve as an alternative to the drugs already established in oncologic treatment. Drug-induced nephrotoxicity leading to acute kidney injury frequently accompanies cancer treatment, and thus there is a need to research the effects of betulin derivatives on renal cells. The objective of our study was to assess the influence of the betulin derivatives 28-propynylobetulin (EB5) and 29-diethoxyphosphoryl-28-propynylobetulin (ECH147) on the expression of TGFβ1, BMP2 and GDF15 in renal proximal tubule epithelial cells (RPTECs) cultured in vitro. The changes in mRNA expression and copy numbers were assessed using real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) and the standard curve method, respectively. An enzyme-linked immunosorbent assay (ELISA) was used to evaluate the effect of the betulin derivatives on the protein concentration in the culture media's supernatant. The assessment of the betulin derivatives' influence on gene expression demonstrated that the mRNA level and protein concentration did not always correlate with each other. Each of the tested compounds affected the mRNA expression. The RT-qPCR analyses showed that EB5 and ECH147 induced effects similar to those of betulin or cisplatin and resulted in a decrease in the mRNA copy number of all the analyzed genes. The ELISA demonstrated that EB5 and ECH147 elevated the protein concentration of TGFβ1 and GDF15, while the level of BMP2 decreased. The concentration of the derivatives used in the treatment was crucial, but the effects did not always exhibit a simple linear dose-dependent relationship. Betulin and its derivatives, EB5 and ECH147, influenced the gene expression of TGFβ1, BMP2 and GDF15 in the renal proximal tubule epithelial cells. The observed effects raise the question of whether treatment with these compounds could promote the development of renal fibrosis.