Cellular senescence and acute kidney injury

Coixol Protects Against Acute Kidney Injury by Reducing Cell Senescence

Acute kidney injury (AKI) is associated with increased in-hospital mortality, yet effective therapeutic agents remain limited. Coixol, a polyphenolic compound derived from Coix, possesses anti-inflammatory properties, but its role in AKI remains unclear. In this study, we demonstrate that Coixol exerts protective effects against ischemia/reperfusion (I/R)-induced AKI by alleviating cellular senescence. Coixol treatment significantly reduced serum creatinine (SCr) and blood urea nitrogen (BUN) levels and decreased the expression of KIM1 and NGAL. RNA sequencing and validation experiments revealed that Coixol suppressed cellular senescence in AKI. Through a weighted gene co-expression network analysis and machine learning, we identified Plaur as a key target of Coixol, which was further validated using RNA-seq data. Notably, Plaur overexpression in AKI mice diminished the protective effects of Coixol, confirming its crucial role. Additionally, molecular docking and molecular dynamics simulations demonstrated strong binding affinity between Coixol and Plaur. These findings highlight Coixol as a promising renal protective agent targeting Plaur and cellular senescence in AKI.

Rational Design of Fluoro-photoacoustic Probes for In Situ Imaging of Endogenous β-Galactosidase Activity and Autophagy

In situ tracking of lysosomal biomarkers has facilitated the unraveling of complex lysosome-associated biological processes and functions. Conventional lysosomal probes typically rely on amine-containing motifs for lysosomal accumulation; however, these motifs would impact lysosomal acidity and disrupt cellular homeostasis due to the proton buffering. To address these issues, this study reports a new strategy for constructing nonamino-dependent lysosomal tracking probes by incorporating an acid-responsive and noninvasive fluoro-photoacoustic scaffold HD-BTZ. Leveraging an ICT mechanism, the HD-BTZ scaffold could respond to the acid environment, enabling in situ visualization of lysosomal dynamics with minimal proton buffering effects. As a proof of concept, two activable molecular probes, HD-BTZ-gal and HD-BTZ-photo, were designed by integrating β-galactosidase's substrate or photolytic protecting groups into the HD-BTZ fluorophore scaffold for in situ tracking of β-galactosidase in lysosomes and lysosome-associated autophagy, respectively. The probes exhibit excellent dual-target activation properties, for which the HD-BTZ-gal probe enables in situ imaging of lysosomal β-galactosidase, while the HD-BTZ-photo probe could be employed for in situ tracking of autophagy by monitoring the dynamic changes in lysosomal pH in living cells. In vivo experiments showed that HD-BTZ-gal allowed for fluorescence/photoacoustic dual-mode imaging of chemotherapy-induced senescence in tumors, suggesting that this strategy could provide an effective approach for evaluating and monitoring age-related diseases.

Update of cellular senescence in kidney fibrosis: from mechanism to potential interventions

Kidney fibrosis is the final common pathway of virtually all chronic kidney disease (CKD). However, despite great progress in recent years, no targeted antifibrotic therapies have been approved. Epidemiologic, clinical, and molecular evidence suggest that aging is a major contributor to the increasing incidence of CKD. Senescent renal tubular cells, fibroblasts, endothelial cells, and podocytes have been detected in the kidneys of patients with CKD and animal models. Nonetheless, although accumulated evidence supports the essential role of cellular senescence in CKD, the mechanisms that promote cell senescence and how senescent cells contribute to CKD remain largely unknown. In this review, we summarize the features of the cellular senescence of the kidney and discuss the possible functions of senescent cells in the pathogenesis of kidney fibrosis. We also address whether pharmacological approaches targeting senescent cells can be used to retard the the progression of kidney fibrosis.

Non-Canonical STING-PERK Pathway Modulation of Cellular Senescence and Therapeutic Response in Sepsis-Associated Acute Kidney Injury

Abstract-This study explored the role of the non-canonical STING-PERK signaling pathway in sepsis-associated acute kidney injury (SA-AKI). Gene expression data from the GEO database and serum STING protein levels in patients with SA-AKI were analyzed. An LPS-induced mouse model and an in vitro model using HK-2 cells were used to investigate the role of STING in SA-AKI. STING expression was suppressed using shRNA silencing technology and the STING inhibitor C176. Kidney function, inflammatory markers, apoptosis, and senescence were measured. The role of the STING-PERK pathway was investigated by silencing PERK in HK-2 cells and administering the PERK inhibitor GSK2606414. STING mRNA expression and serum STING protein levels were significantly higher in patients with SA-AKI. Suppressing STING expression improved kidney function, reduced inflammation, and inhibited apoptosis and senescence. Silencing PERK or administering GSK2606414 suppressed the inflammatory response, cell apoptosis, and senescence, suggesting that PERK is a downstream effector in the STING signaling pathway. The STING-PERK signaling pathway exacerbates cell senescence and apoptosis in SA-AKI. Inhibiting this pathway could provide potential therapeutic targets for SA-AKI treatment.

mTOR Inhibition limits LPS induced acute kidney injury and ameliorates hallmarks of cellular senescence

Sepsis-induced acute kidney injury (AKI) can lead to chronic renal dysfunction with accelerated renal aging. Activation of the mammalian target of rapamycin (mTOR) is implicated in the initiation and progression of renal injury. This study investigates the effectiveness of the mTOR inhibitor, rapamycin, in mitigating kidney injury and explores the underlying mechanisms. AKI was induced by intraperitoneal administration of a solution containing 10 mg/kg of lipopolysaccharide (LPS) in a mouse model. Two groups of endotoxemic mice received pre- and post- treatment with rapamycin. Whole-genome DNA methylation analysis was performed on renal proximal tubular epithelial cells (RPTEC). In the LPS-induced AKI mouse model, rapamycin treatment significantly reduced creatinine levels, preserved renal parenchyma, and counteracted the endothelial-to-mesenchymal transition (EndMT) by inhibiting the ERK pathway. Whole-genome DNA methylation analysis revealed that LPS induced aberrant methylation, particularly in genes associated with premature aging, including ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1/CD39) and wolframin ER transmembrane glycoprotein (WFS1). Accordingly, endotoxemic mice exhibited decreased CD39 expression and klotho down-regulation, both of which were reversed by rapamycin, suggesting an anti-aging effect in AKI. mTOR inhibition may represent a promising strategy to prevent accelerated renal aging in LPS-induced AKI and potentially slow the progression of chronic kidney disease.

The Potential of Naturally Derived Compounds for Treating Chronic Kidney Disease: A Review of Autophagy and Cellular Senescence

Chronic kidney disease (CKD) is characterized by irreversible progressive worsening of kidney function leading to kidney failure. CKD is viewed as a clinical model of premature aging and to date, there is no treatment to reverse kidney damage. The well-established treatment for CKD aims to control factors that may aggravate kidney progression and to provide kidney protection effects to delay the progression of kidney disease. As an alternative, Traditional Chinese Medicine (TCM) has been shown to have fewer adverse effects for CKD patients. However, there is a lack of clinical and molecular studies investigating the mechanisms by which natural products used in TCM can improve CKD. In recent years, autophagy and cellular senescence have been identified as key contributors to aging and age-related diseases. Exploring the potential of natural products in TCM to target these processes in CKD patients could slow disease progression. A better understanding of the characteristics of these natural products and their effects on autophagy and cellular senescence through clinical studies, coupled with the use of these products as complementary therapy alongside mainstream treatment, may maximize therapeutic benefits and minimize adverse effects for CKD patients. While promising, there is currently a lack of thorough research on the potential synergistic effects of these natural products. This review examines the use of natural products in TCM as an alternative treatment for CKD and discusses their active ingredients in terms of renoprotection, autophagy, and cellular senescence.

Mitochondrial dysfunction in acute kidney injury

Acute kidney injury (AKI) is a systemic clinical syndrome increasing morbidity and mortality worldwide in recent years. Renal tubular epithelial cells (TECs) death caused by mitochondrial dysfunction is one of the pathogeneses. The imbalance of mitochondrial quality control is the main cause of mitochondrial dysfunction. Mitochondrial quality control plays a crucial role in AKI. Mitochondrial quality control mechanisms are involved in regulating mitochondrial integrity and function, including antioxidant defense, mitochondrial quality control, mitochondrial DNA (mtDNA) repair, mitochondrial dynamics, mitophagy, and mitochondrial biogenesis. Currently, many studies have used mitochondrial dysfunction as a targeted therapeutic strategy for AKI. Therefore, this review aims to present the latest research advancements on mitochondrial dysfunction in AKI, providing a valuable reference and theoretical foundation for clinical prevention and treatment of this condition, ultimately enhancing patient prognosis.

Integrin subunit beta 6 is a potential diagnostic marker for acute kidney injury in patients with diabetic kidney disease: a single cell sequencing data analysis

BACKGROUND

Diabetic kidney disease (DKD), a prevalent complication of diabetes mellitus, is often associated with acute kidney injury (AKI). Thus, the development of preventive and therapeutic strategies is crucial for delaying the progression of AKI and DKD.

METHODS

The GSE183276 dataset, comprising the data of 20 healthy controls and 12 patients with AKI, was downloaded from the Gene Expression Omnibus (GEO) database to analyze the AKI group. For analyzing the DKD group, the GSE131822 dataset, comprising the data of 3 healthy controls and 3 patients with DKD, was downloaded from the GEO database. The common differentially expressed genes (DEGs) in renal tubular epithelial cells (TECs) were subjected to enrichment analyses. Next, a protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes database to analyze gene-related regulatory networks. Finally, the AKI animal models and the DKD and AKI cell models were established, and the reliability of the identified genes was validated using quantitative real-time polymerase chain reaction analysis.

RESULTS

Functional analysis was performed with 40 common DEGs in TECs. Eight hub genes were identified using the PPI and gene-related networks. Finally, validation experiments with the in vivo animal model and the in vitro cellular model revealed the four common DEGs. Four DEGs that share molecular mechanisms in the pathogenesis of DKD and AKI were identified. In particular, the expression of Integrin Subunit Beta 6(ITGB6), a hub and commonly upregulated gene, was upregulated in the in vitro models.

CONCLUSION

ITGB6 may serve as a biomarker for early AKI diagnosis in patients with DKD and as a target for early intervention therapies.

p53 dependence of senescence markers p21v1 and p21v2 in aging and acute injury

The senescence phenotype is heterogeneous, as observed by the context-dependent differential expression of senescence markers. Here, we provide evidence to demonstrate an inverse relationship in the expression pattern of the two murine variants of p21 (p21v1, and p21v2) in aging and hemorrhagic shock. While an upregulation of p21v1 was observed following hemorrhagic shock injury, p21v2 was upregulated in the aged mouse. We further show that the p21v1 response is, at least, partially independent of p53.

Nanotherapeutic kidney cell-specific targeting to ameliorate acute kidney injury

Acute kidney injury (AKI) increases the risk of in-hospital death, adds to expense of care, and risk of early chronic kidney disease. AKI often follows an acute event such that timely treatment could ameliorate AKI and potentially reduce the risk of additional disease. Despite therapeutic success of dexamethasone in animal models, clinical trials have not demonstrated broad success. To improve the safety and efficacy of dexamethasone for AKI, we developed and characterized a novel, kidney-specific nanoparticle enabling specific within-kidney targeting to proximal tubular epithelial cells provided by the megalin ligand cilastatin. Cilastatin and dexamethasone were complexed to H-Dot nanoparticles, which were constructed from generally recognized as safe components. Cilastatin/Dexamethasone/H-Dot nanotherapeutics were found to be stable at plasma pH and demonstrated salutary release kinetics at urine pH. In vivo, they were specifically biodistributed to the kidney and bladder, with 75% recovery in the urine and with reduced systemic toxicity compared to native dexamethasone. Cilastatin complexation conferred proximal tubular epithelial cell specificity within the kidney in vivo and enabled dexamethasone delivery to the proximal tubular epithelial cell nucleus in vitro. The Cilastatin/Dexamethasone/H-Dot nanotherapeutic improved kidney function and reduced kidney cellular injury when administered to male C57BL/6 mice in two translational models of AKI (rhabdomyolysis and bilateral ischemia reperfusion). Thus, our design-based targeting and therapeutic loading of a kidney-specific nanoparticle resulted in preservation of the efficacy of dexamethasone, combined with reduced off-target disposition and toxic effects. Hence, our study illustrates a potential strategy to target AKI and other diseases of the kidney.

Therapeutic approaches targeting aging and cellular senescence in Huntington's disease

Huntington's disease (HD) is a devastating neurodegenerative disease that is manifested by a gradual loss of physical, cognitive, and mental abilities. As the disease advances, age has a major impact on the pathogenic signature of mutant huntingtin (mHTT) protein aggregation. This review aims to explore the intricate relationship between aging, mHTT toxicity, and cellular senescence in HD. Scientific data on the interplay between aging, mHTT, and cellular senescence in HD were collected from several academic databases, including PubMed, Google Scholar, Google, and ScienceDirect. The search terms employed were "AGING," "HUNTINGTON'S DISEASE," "MUTANT HUNTINGTIN," and "CELLULAR SENESCENCE." Additionally, to gather information on the molecular mechanisms and potential therapeutic targets, the search was extended to include relevant terms such as "DNA DAMAGE," "OXIDATIVE STRESS," and "AUTOPHAGY." According to research, aging leads to worsening HD pathophysiology through some processes. As a result of the mHTT accumulation, cellular senescence is promoted, which causes DNA damage, oxidative stress, decreased autophagy, and increased inflammatory responses. Pro-inflammatory cytokines and other substances are released by senescent cells, which may worsen the neuronal damage and the course of the disease. It has been shown that treatments directed at these pathways reduce some of the HD symptoms and enhance longevity in experimental animals, pointing to a new possibility of treating the condition. Through their amplification of the harmful effects of mHTT, aging and cellular senescence play crucial roles in the development of HD. Comprehending these interplays creates novel opportunities for therapeutic measures targeted at alleviating cellular aging and enhancing HD patients' quality of life.

Oxidative stress and senescence in aging kidneys: the protective role of SIRT1

Aging leads to a gradual decline in kidney function, making the kidneys increasingly vulnerable to various diseases. Oxidative stress, together with cellular senescence, has been established as paramount in promoting the aging process of the kidney. Oxidative stress, defined as an imbalance between ROS formation and antioxidant defense mechanisms, has been implicated in the kidney's cellular injury, inflammation, and premature senescence. Concurrently, the accumulation of SCs in the kidney also exacerbates oxidative stress via the secretion of pro-inflammatory and tissue-damaging factors as the senescence-associated secretory phenotype (SASP). Recently, SIRT1, a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, has been pivotal in combating oxidative stress and cellular senescence in the aging kidney. SIRT1 acts as a potential antioxidant molecule through myriad pathways that influence diverse transcription factors and enzymes essential in maintaining redox homeostasis. SIRT1 promotes longevity and renal health by modulating the acetylation of cell cycle and senescence pathways. This review covers the complex relationship between oxidative stress and cellular senescence in the aging kidney, emphasizing the protective role of SIRT1. See also the graphical abstract(Fig. 1).

Galectin-8 counteracts folic acid-induced acute kidney injury and prevents its transition to fibrosis

Acute kidney injury (AKI), characterized by a sudden decline in kidney function involving tubular damage and epithelial cell death, can lead to progressive tissue fibrosis and chronic kidney disease due to interstitial fibroblast activation and tissue repair failures that lack direct treatments. After an AKI episode, surviving renal tubular cells undergo cycles of dedifferentiation, proliferation and redifferentiation while fibroblast activity increases and then declines to avoid an exaggerated extracellular matrix deposition. Appropriate tissue recovery versus pathogenic fibrotic progression depends on fine-tuning all these processes. Identifying endogenous factors able to affect any of them may offer new therapeutic opportunities to improve AKI outcomes. Galectin-8 (Gal-8) is an endogenous carbohydrate-binding protein that is secreted through an unconventional mechanism, binds to glycosylated proteins at the cell surface and modifies various cellular activities, including cell proliferation and survival against stress conditions. Here, using a mouse model of AKI induced by folic acid, we show that pre-treatment with Gal-8 protects against cell death, promotes epithelial cell redifferentiation and improves renal function. In addition, Gal-8 decreases fibroblast activation, resulting in less expression of fibrotic genes. Gal-8 added after AKI induction is also effective in maintaining renal function against damage, improving epithelial cell survival. The ability to protect kidneys from injury during both pre- and post-treatments, coupled with its anti-fibrotic effect, highlights Gal-8 as an endogenous factor to be considered in therapeutic strategies aimed at improving renal function and mitigating chronic pathogenic progression.

Clinical and histopathological characteristics of acute kidney injury in a cohort of brain death donors with procurement biopsies

BACKGROUND

Kidney biopsies are routinely used for diagnostic and prognostic purposes but their utility in the intensive care unit (ICU) setting is limited. We investigated the associations of clinical and histopathological risk factors with ICU-acute kidney injury (AKI) in donors with brain death (DBD) with kidneys of lower quality and procurement biopsies.

METHODS

Overall, 221 donors with brain death, 239 biopsies and 197 recipients were included. The biopsies were reread and scored according to the Banff recommendations. Clinical and histopathological data were compared between donors with and without AKI defined by serum creatinine and by urine output. Logistic regression analysis was applied to identify independent clinical and histopathological risk factors for both phenotypes. Lastly, the impact of each AKI phenotype on outcome was explored. AKI was diagnosed based on the RIFLE (Risk, Injury, Failure, Loss of function, End-stage kidney disease) AKIN (Acute Kidney Injury Network) or KDIGO (Kidney Disease Improving Global Outcomes) criteria.

RESULTS

Acute kidney injury occurred in 65% of donors based both upon serum creatinine and by urine output. Serum creatinine was able to better discriminate AKI. Multiorgan failure and severe AKI were captured by serum creatinine, and hemodynamic instability by urine output. Donors with serum creatinine-AKI showed lower chronic macrovascular scores, while donors with urine output-AKI had higher chronic microvascular and tubulointerstitial scores. Tubular injury was similar between the subgroups. Except for delayed graft function and one-year death-censored graft survival, the other short-term recipient outcomes were similar for both AKI phenotypes.

CONCLUSION

Serum creatinine is more suitable than urine output for defining AKI in donors with brain death. There are distinct clinical risk factors for each AKI-ICU phenotype. Donor AKI phenotype does not predict the recipient´s prognosis. Kidney biopsies do not seem to confer any tangible benefit in defining AKI in donors with brain death.

From premature birth to premature kidney disease: does accelerated aging play a role?

As the limits of fetal viability have increased over the past 30 years, there has been a growing body of evidence supporting the idea that chronic disease should be taken into greater consideration in addition to survival after preterm birth. Accumulating evidence also suggests there is early onset of biologic aging after preterm birth. Similarly, chronic kidney disease (CKD) is also associated with a phenotype of advanced biologic age which exceeds chronologic age. Yet, significant knowledge gaps remain regarding the link between premature biologic age after preterm birth and kidney disease. This review summarizes the four broad pillars of aging, the evidence of premature aging following preterm birth, and in the setting of CKD. The aim is to provide additional plausible biologic mechanisms to explore the link between preterm birth and CKD. There is a need for more research to further elucidate the biologic mechanisms of the premature aging paradigm and kidney disease after preterm birth. Given the emerging research on therapies for premature aging, this paradigm could create pathways for prevention of advanced CKD.

Short-Term, Mid-Term, and Long-Term Outcomes after Deceased Donor Kidney Transplantation in Patients with AKI: A Systematic Review and Meta-Analysis

Key Points

This study reviews the willingness to use kidneys from donors who have experienced AKI during transplantation and provides a thorough analysis of the existing literature. While delayed graft function is more common, primary nonfunction and acute rejection rates appear comparable, as do allograft function and graft survival compared with non-AKI donor kidneys. Considering the shortage of available organs and the high mortality rate of patients on dialysis, the use of donors with AKI as a source for kidney transplantation is a viable alternative.

Background

AKI is a common complication in hospitalized patients and may occur in potential kidney donors. Observational studies have suggested that kidney transplantation in patients with AKI is feasible and safe, but no systematic evaluation has been performed.

Methods

We performed a systematic review and meta-analysis to evaluate the outcomes of kidney transplantation in patients with AKI. We searched MEDLINE, Embase, Cochrane, Google Scholar, and other databases for studies reporting outcomes of donor kidneys with AKI. We included single-center, multicenter, and registry-based studies and analyzed them according to the definition and severity of AKI. End points were primary and delayed graft function (DGF), primary nonfunction (PNF), length of hospital stay, rejection, graft function, and patient and graft survival at 1, 3, 5, and 8–10 years after transplantation. This study was registered in PROSPERO, number CRD42021260088.

Results

We identified 33 single-center, four multicenter, and seven registry studies with more than 100,000 patients published between 2005 and 2022. Recipients from donors with AKI had a higher risk of DGF (relative risk, 1.51; 95% confidence interval [CI], 1.35 to 1.68). Graft function at discharge was worse in the AKI group (MDCrea [95% CI]: 0.96 mg/dl [0.36 to 1.56, I2=96%], MDGFR [95% CI]: −8.88 ml/min per 1.73 m2 [−15.32 to −2.44, I2=93%]), but improved thereafter and was similar in both groups at 3 months after transplantation (MDCrea [95% CI]: −0.05 mg/dl [−0.18 to 0.07, I2=0%], MDGFR [95% CI]: −1.83 ml/min per 1.73 m2 [−5.29 to 1.63, I2=91%]). Primary nonfunction and patient and graft survival were similar at 1, 3, 5, and 8–10 years after transplantation. There were no differences in rejections regardless of AKI definition and severity.

Conclusions

Transplantation of kidneys with AKI is associated with satisfactory short-term and long-term outcomes and should be pursued to increase the donor pool.

Molecular mechanism of circHIPK3 in mitochondrial function in septic acute kidney injury

Cell senescence, glycolysis, and mitochondrial deficit jointly regulate the development of septic acute kidney injury (SAKI). This study aimed to explore the role of circular RNA HIPK3 (circHIPK3) in mitochondrial function in SAKI. The SAKI mouse model was established by Candida albicans infection, followed by Western blot assay, measurements of serum lactate, and adenosine triphosphate (ATP), 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimi-dazolylcarbocyanine iodide (JC-1) staining and flow cytometry. Human renal tubular epithelial cells were treated with lipopolysaccharide to establish the SAKI cell model, followed by cell counting kit-8 assay, tests of hexokinase activity, lactate production, oxygen consumption rate, extracellular acidification rate, ATP, and JC-1 staining, and Western blot assay. The roles of mitochondrial pyruvate carrier 1 (MPC1) were validated by kidney function tests, hematoxylin and eosin staining, periodic acid-Schiff staining, and SA-β-gal staining. circHIPK3 downregulation reduced glycolysis and mitochondrial dysfunction both in vivo and in vitro through the microRNA (miR)-148b-3p/DNMT1/3a/Klotho axis. Inhibition of miR-148b-3p or Klotho increased glycolysis and mitochondrial dysfunction. Knockdown of MPC1 increased lactate content and decreased ATP levels and MMP both in vivo and in vitro. Collectively, circHIPK3, in concert with the miR-148b-3p/DNMT1/3a/Klotho axis, increased glycolysis, and inhibited the negative regulation of lactate production by MPC1, and aggravated mitochondrial dysfunction and cell senescence in SAKI.

Cellular senescence in acute kidney injury: Target and opportunity

Acute kidney injury (AKI) is a common clinical disease with a high incidence and mortality rate. It typically arises from hemodynamic alterations, sepsis, contrast agents, and toxic drugs, instigating a series of events that culminate in tissue and renal damage. This sequence of processes often leads to acute renal impairment, prompting the initiation of a repair response. Cellular senescence is an irreversible arrest of the cell cycle. Studies have shown that renal cellular senescence is closely associated with AKI through several mechanisms, including the promotion of oxidative stress and inflammatory response, telomere shortening, and the down-regulation of klotho expression. Exploring the role of cellular senescence in AKI provides innovative therapeutic ideas for both the prevention and treatment of AKI. Furthermore, it has been observed that targeted removal of senescent cells in vivo can efficiently postpone senescence, resulting in an enhanced prognosis for diseases associated with senescence. This article explores the effects of common anti-senescence drugs senolytics and senostatic and lifestyle interventions on renal diseases, and mentions the rapid development of mesenchymal stem cells (MSCs). These studies have taken senescence-related research to a new level. Overall, this article comprehensively summarizes the studies on cellular senescence in AKI, aiming is to elucidate the relationship between cellular senescence and AKI, and explore treatment strategies to improve the prognosis of AKI.

Senescent-like macrophages mediate angiogenesis for endplate sclerosis via IL-10 secretion in male mice

Endplate sclerosis is a notable aspect of spine degeneration or aging, but the mechanisms remain unclear. Here, we report that senescent macrophages accumulate in the sclerotic endplates of lumbar spine instability (LSI) or aging male mouse model. Specifically, knockout of cdkn2a (p16) in macrophages abrogates LSI or aging-induced angiogenesis and sclerosis in the endplates. Furthermore, both in vivo and in vitro studies indicate that IL-10 is the primary elevated cytokine of senescence-related secretory phenotype (SASP). Mechanistically, IL-10 increases pSTAT3 in endothelial cells, leading to pSTAT3 directly binding to the promoters of Vegfa, Mmp2, and Pdgfb to encourage their production, resulting in angiogenesis. This study provides information on understanding the link between immune senescence and endplate sclerosis, which might be useful for therapeutic approaches.

Galectins in epithelial-mesenchymal transition: roles and mechanisms contributing to tissue repair, fibrosis and cancer metastasis

Galectins are soluble glycan-binding proteins that interact with a wide range of glycoproteins and glycolipids and modulate a broad spectrum of physiological and pathological processes. The expression and subcellular localization of different galectins vary among tissues and cell types and change during processes of tissue repair, fibrosis and cancer where epithelial cells loss differentiation while acquiring migratory mesenchymal phenotypes. The epithelial-mesenchymal transition (EMT) that occurs in the context of these processes can include modifications of glycosylation patterns of glycolipids and glycoproteins affecting their interactions with galectins. Moreover, overexpression of certain galectins has been involved in the development and different outcomes of EMT. This review focuses on the roles and mechanisms of Galectin-1 (Gal-1), Gal-3, Gal-4, Gal-7 and Gal-8, which have been involved in physiologic and pathogenic EMT contexts.

Protective Effect of Curcumin on D-Galactose-Induced Senescence and Oxidative Stress in LLC-PK1 and HK-2 Cells

D-galactose has been widely used as an inducer of cellular senescence and pathophysiological processes related to aging because it induces oxidative stress. On the other hand, the consumption of antioxidants such as curcumin can be an effective strategy to prevent phenotypes related to the enhanced production of reactive oxygen species (ROS), such as aging and senescence. This study aimed to evaluate the potential protective effect of curcumin on senescence and oxidative stress and endoplasmic reticulum stress induced by D-galactose treatment in Lilly Laboratories Culture-Porcine Kidney 1 (LLC-PK1) and human kidney 2 (HK-2) proximal tubule cell lines from pig and human, respectively. For senescence induction, cells were treated with 300 mM D-galactose for 120 h and, to evaluate the protective effect of the antioxidant, cells were treated with 5 µM curcumin for 24 h and subsequently treated with curcumin + D-galactose for 120 h. In LLC-PK1 cells, curcumin treatment decreased by 20% the number of cells positive for senescence-associated (SA)-β-D-galactosidase staining and by 25% the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and increased by 40% lamin B1 expression. In HK-2 cells, curcumin treatment increased by 60% the expression of proliferating cell nuclear antigen (PCNA, 50% Klotho levels, and 175% catalase activity. In both cell lines, this antioxidant decreased the production of ROS (20% decrease for LLC-PK1 and 10 to 20% for HK-2). These data suggest that curcumin treatment has a moderate protective effect on D-galactose-induced senescence in LLC-PK1 and HK-2 cells.

The AKI-to-CKD Transition: The Role of Uremic Toxins

After acute kidney injury (AKI), renal function continues to deteriorate in some patients. In a pro-inflammatory and profibrotic environment, the proximal tubules are subject to maladaptive repair. In the AKI-to-CKD transition, impaired recovery from AKI reduces tubular and glomerular filtration and leads to chronic kidney disease (CKD). Reduced kidney secretion capacity is characterized by the plasma accumulation of biologically active molecules, referred to as uremic toxins (UTs). These toxins have a role in the development of neurological, cardiovascular, bone, and renal complications of CKD. However, UTs might also cause CKD as well as be the consequence. Recent studies have shown that these molecules accumulate early in AKI and contribute to the establishment of this pro-inflammatory and profibrotic environment in the kidney. The objective of the present work was to review the mechanisms of UT toxicity that potentially contribute to the AKI-to-CKD transition in each renal compartment.

The early diagnosis and pathogenic mechanisms of sepsis-related acute kidney injury

Sepsis is a syndrome caused by an imbalance in the inflammatory response of the body caused by an infection that leads to organ dysfunction, with the kidney being one of the most commonly affected organs. Sepsis-related acute kidney injury (SAKI) is strongly linked to increased mortality and poor clinical outcomes. Early diagnosis and treatment can significantly reduce patient mortality. On the other hand, the pathogenesis of SAKI is not fully understood, and early diagnosis of SAKI is a clinical challenge. Therefore, the current review describes biomarkers of acute kidney injury in sepsis and discusses the various pathogenic mechanisms involved in the progression of acute kidney injury in sepsis to develop new clinical treatment avenues.

In vivo dynamics of senescence in rhabdomyolysis-induced acute kidney injury

Cellular senescence is involved in the pathogenesis of various diseases, including acute kidney injury (AKI). AKI is defined as a sudden loss of kidney function. In severe AKI, irreversible loss of kidney cells can occur. Cellular senescence might contribute to this maladaptive tubular repair, though, its pathophysiological role in vivo is incompletely understood. In this study, we used p16-CreERT2-tdTomato mice in which cells with high p16 expression, a prototypical senescent marker, are labeled with tdTomato fluorescence. Then, we induced AKI by rhabdomyolysis and traced the cells with high p16 expression following AKI. We proved that the induction of senescence was observed predominantly in proximal tubular epithelial cells (PTECs) and occurred in a relatively acute phase within 1-3 days after AKI. These acute senescent PTECs were spontaneously eliminated by day 15. On the contrary, the generation of senescence in PTECs persisted during the chronic recovery phase. We also confirmed that the kidney function did not fully recover on day 15. These results suggest that the chronic generation of senescent PTECs might contribute to maladaptive recovery from AKI and lead to chronic kidney disease progression.

The role of IL-17 in acute kidney injury

Acute kidney injury (AKI) is a common clinical kidney disease with a high mortality rate. AKI is caused by a variety of factors, including sepsis, ischemia, and nephrotoxic drugs, and can progress to chronic kidney disease and end-stage renal disease. Numerous studies have suggested that cytokines can be used as therapeutic targets for AKI. IL-17 is a pro-inflammatory cytokine that not only participates in the host defense and the development of autoimmune diseases but also is linked to AKI due to a variety of factors. This review will give an overview of the structure, signaling pathways, and biological functions of IL-17, as well as its role in AKI, to show that IL-17 is a potential target for the prevention and treatment of AKI.

Long-Term Effects of Severe Burns on the Kidneys: Research Advances and Potential Therapeutic Approaches

Burns are a seriously underestimated form of trauma that not only damage the skin system but also cause various complications, such as acute kidney injury (AKI). Recent clinical studies have shown that the proportion of chronic kidney diseases (CKD) in burn patients after discharge is significantly higher than that in the general population, but the mechanism behind this is controversial. The traditional view is that CKD is associated with hypoperfusion, AKI, sepsis, and drugs administered in the early stages of burns. However, recent studies have shown that burns can cause long-term immune dysfunction, which is a high-risk factor for CKD. This suggests that burns affect the kidneys more than previously recognized. In other words, severe burns are not only an acute injury but also a chronic disease. Neglecting to study long-term kidney function in burn patients also results in a lack of preventive and therapeutic methods being developed. Furthermore, stem cells and their exosomes have shown excellent comprehensive therapeutic properties in the prevention and treatment of CKD, making them increasingly the focus of research attention. Their engineering strategy further improved the therapeutic performance. This review will focus on the research advances in burns on the development of CKD, illustrating the possible mechanism of burn-induced CKD and introducing potential biological treatment options and their engineering strategies.

Substantial Downregulation of Mitochondrial and Peroxisomal Proteins during Acute Kidney Injury revealed by Data-Independent Acquisition Proteomics

Acute kidney injury (AKI) manifests as a major health concern, particularly for the elderly. Understanding AKI-related proteome changes is critical for prevention and development of novel therapeutics to recover kidney function and to mitigate the susceptibility for recurrent AKI or development of chronic kidney disease. In this study, mouse kidneys were subjected to ischemia-reperfusion injury, and the contralateral kidneys remained uninjured to enable comparison and assess injury-induced changes in the kidney proteome. A fast-acquisition rate ZenoTOF 7600 mass spectrometer was introduced for data-independent acquisition (DIA) for comprehensive protein identification and quantification. Short microflow gradients and the generation of a deep kidney-specific spectral library allowed for high-throughput, comprehensive protein quantification. Upon AKI, the kidney proteome was completely remodeled, and over half of the 3,945 quantified protein groups changed significantly. Downregulated proteins in the injured kidney were involved in energy production, including numerous peroxisomal matrix proteins that function in fatty acid oxidation, such as ACOX1, CAT, EHHADH, ACOT4, ACOT8, and Scp2. Injured mice exhibited severely declined health. The comprehensive and sensitive kidney-specific DIA assays highlighted here feature high-throughput analytical capabilities to achieve deep coverage of the kidney proteome and will serve as useful tools for developing novel therapeutics to remediate kidney function.

Diminished Tubule Epithelial Farnesoid X Receptor Expression Exacerbates Inflammation and Fibrosis Response in Aged Rat Kidney

The age-associated functional decline of the kidney is accompanied by structural changes including glomerular sclerosis and interstitial fibrosis. Aging kidneys also exhibit increased vulnerability in stressful environmental conditions. In this study, we assessed the differences in responses between young and aged animals to folic acid (FA)-induced renal fibrosis. To monitor the effects of aging on FA-induced kidney fibrosis, we administered FA (250 mg/kg) to young (6-month old) and aged (20-month old) rats. The development of severe fibrosis was only detected in aged rat kidneys, which was accompanied by increased kidney injury and inflammation. Furthermore, we found that FA-treated aged rats had significantly lower farnesoid X receptor (FXR) expression in the tubular epithelial cells than the rats not treated with FA. Interestingly, the extent of inflammation was severe in the kidneys of aged rat, where the FXR expression was low. To explore the role of FXR in kidney inflammation, in vitro studies were performed using NRK52E kidney tubule epithelial cells. NF-κB activation by lipopolysaccharide treatment induces chemokine production in NRK52E cells. The activation of FXR by obeticholic acid significantly reduced the transcriptional activity of NF-κB and chemokine production. In contrast, FXR knockdown increased LPS-induced chemokine production in NRK52E cells. Finally, FXR-knockout mice that were administered FA showed increased inflammation and severe fibrosis. In summary, we demonstrated that diminished FXR expression in the epithelial cells of the renal tubules exacerbated the fibrotic response in aged rat kidneys by upregulating pro-inflammatory NF-κB activation.

Gender and Renal Insufficiency: Opportunities for Their Therapeutic Management?

Acute kidney injury (AKI) is a major clinical problem associated with increased morbidity and mortality. Despite intensive research, the clinical outcome remains poor, and apart from supportive therapy, no other specific therapy exists. Furthermore, acute kidney injury increases the risk of developing chronic kidney disease (CKD) and end-stage renal disease. Acute tubular injury accounts for the most common intrinsic cause of AKI. The main site of injury is the proximal tubule due to its high workload and energy demand. Upon injury, an intratubular subpopulation of proximal epithelial cells proliferates and restores the tubular integrity. Nevertheless, despite its strong regenerative capacity, the kidney does not always achieve its former integrity and function and incomplete recovery leads to persistent and progressive CKD. Clinical and experimental data demonstrate sexual differences in renal anatomy, physiology, and susceptibility to renal diseases including but not limited to ischemia-reperfusion injury. Some data suggest the protective role of female sex hormones, whereas others highlight the detrimental effect of male hormones in renal ischemia-reperfusion injury. Although the important role of sex hormones is evident, the exact underlying mechanisms remain to be elucidated. This review focuses on collecting the current knowledge about sexual dimorphism in renal injury and opportunities for therapeutic manipulation, with a focus on resident renal progenitor stem cells as potential novel therapeutic strategies.