Radiation-induced premature cellular senescence involved in glomerular diseases in rats

Innovative insights: ITLN1 modulates renal injury in response to radiation

Radiation-induced kidney injury is a common side effect of radiotherapy, as the pelvic region is in close proximity to the kidneys, posing a risk of inducing radiation-induced kidney injury when treating any pelvic malignancies with radiotherapy. This type of injury typically manifests as chronic kidney disease a few months after radiotherapy, with the potential to progress to end-stage renal disease. Radiation-induced damage involves various components of the kidney, including glomeruli, tubules, interstitium, and extracellular matrix. Therefore, investigating its molecular mechanisms is crucial. In this study, we extensively searched literature databases, selecting recent transcriptomic studies related to acute kidney injury (AKI) published in the past decade. We downloaded the raw RNA sequencing datasets GSE30718 and GSE66494 related to AKI from the GEO database and identified that intestinal-type lectin ITLN1 plays a significant role in regulating radiation-induced kidney injury in rats. Differential gene analysis was performed using chip data from the GEO database, and further bioinformatics analysis identified 13 genes that may be involved in regulating kidney injury, with ITLN1 being the most relevant to kidney damage, thus selected as the target gene for this study. Subsequently, a rat model of radiation-induced kidney injury was established for experimental validation, assessing kidney tissue morphology and injury extent through staining observation and immunohistochemical staining. The protective effect of ITLN1 on kidney function was evaluated by measuring changes in rat body weight and blood pressure, serum kidney injury markers, and kidney structure. The experimental results indicate that overexpression of ITLN1 can improve kidney function in rats with radiation-induced kidney injury by activating the Akt/GSK-3β/Nrf2 signaling pathway, suppressing oxidative stress, cell apoptosis, inflammation, cellular senescence, and fibrosis. This study highlights the significant role of ITLN1 in regulating kidney injury, providing a novel target for future treatments of radiation-induced kidney injury.

Integrated metabolomic and lipidomic analysis revealed the protective mechanisms of Erzhi Wan on senescent NRK cells through BRL cells

ETHNOPHARMACOLOGICAL RELEVANCE

Erzhi Wan (EZW), as a prescription of traditional Chinese medicine, has been used for tonifying the liver and kidney. Although past studies have shown that EZW has potential anti-aging effect, the mechanisms associated with cellular metabolomics and lipidomics are not fully understood.

AIM OF THE STUDY

This study aimed to evaluate the anti-aging effect of EZW and investigate the mechanisms associated with cellular metabolomics and lipidomics.

MATERIALS AND METHODS

EZW solution at dosage of 3.6 g/kg in Sprague-Dawley rats was orally administered twice a day for 7 days and serum containing EZW was then collected. NRK cell senescence model induced by D-galactose was established in vitro, and non-contact co-culture cell assay was performed between senescent NRK cells and BRL cells intervened by serum containing EZW. The anti-aging effect of EZW on NRK cells was evaluated by metabolites identification, differential metabolites screening and metabolic pathways analysis through cellular metabolomics with GC-MS and lipidomics with UHPLC-Q-Exactive Orbitrap/MS.

RESULTS

Serum containing EZW indicated a protective effect through intervening BRL cells in non-contact co-culture system with D-gal-induced senescent NRK cells. For metabolic profiles, 71 endogenous metabolites were identified, among which 24 significantly differential metabolites were screened as metabolomics potential biomarkers. For lipidic profiles, 64 lipid components were identified in NRK cell samples under positive ion mode, among which 24 potential biomarkers of lipids were screened, mainly including PC and PE. 127 lipid components were identified in NRK cell samples under negative ion mode, among which 59 potential biomarkers of lipids were screened, including FA, PC, PE, PI and PS. Metabolic pathway analysis demonstrated that the identified differential metabolites found mainly involved in amino acids metabolism, energy metabolism and phospholipid biosynthesis pathways.

CONCLUSION

Serum containing EZW exhibited protective effect on D-gal-induced senescent NRK cells through intervening BRL cells by mainly regulating amino acids metabolism, energy metabolism and phospholipid biosynthesis pathways to possess its anti-aging function, providing a theoretical basis for clinical treatment of EZW.

Cellular senescence and ophthalmic diseases: narrative review

PURPOSE

Cellular senescence is a state of permanent growth arrest whereby a cell reaches its replicative limit. However, senescence can also be triggered prematurely in certain stressors including radiation, oxidative stress, and chemotherapy. This stress-induced senescence has been studied in the context of promoting inflammation, tumor development, and several chronic degenerative diseases of aging. Emerging research has elucidated the role of senescence in various ocular diseases.

METHODS

The literature search was performed using PubMed with using the query (senescence OR aging) AND (eye disease OR ocular disease OR ophthalmic disease OR cornea OR glaucoma OR cataract OR retina) on October 20th, 2022. No time restriction was proposed. Articles were excluded if they were not referenced in English.

RESULTS

Overall, 51 articles regarding senescence and ocular diseases were found and summarized in this study. Several signaling pathways have been implicated in the development of senescence. Currently, senescence has been linked to various corneal and retinal pathologies, as well as cataract and glaucoma. Given the number of pathologies, senolytics, which are small molecules with the ability to selective targeting of senescent cells, can be used as therapeutic or prophylactic agents.

CONCLUSIONS

Senescence has been shown to underlie the pathogenesis of numerous ocular diseases. The overall literature on senescence and ocular disease is growing rapidly. There is an ongoing debate whether or not cellular senescence detected in experiments contributes in a significant way to diseases. Research on understanding the mechanism of senescence from ocular cells and tissues is just beginning. Multiple animal models are required to test potential senolytics. Currently, no studies exist to date which have demonstrated the benefits of senolytic therapies in human studies.

Radioprotective effects of quercetin and curcumin on hepatotoxicity and nephrotoxicity in male Albino rats.. [DOI: 10.21203/rs.3.rs-2727957/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The present study aimed to assess the radioprotective effects of curcumin in combination with quercetin against radiation-induced changes in some histopathological, immunohistochemical, and biophysical parameters. The current study rats had been grouped into control, curcumin, quercetin, gamma irradiated (8 Gy fractionated dose), curcumin pretreated irradiated, quercetin pretreated irradiated, and both curcumin and quercetin pretreated irradiated groups. Gamma radiation exposure resulted in hepatic and renal damage. Administration of curcumin along with quercetin before gamma radiation exposure reduced the liver and kidney damage caused by radiation, demonstrating the radioprotective effects of both curcumin and quercetin antioxidants through free radicals scavenging effects, P53, and TNF-α inhibition, and structural changes measured by Fourier Transform Infrared (FTIR). The cellular damage by gamma radiation is greatly mitigated by administration of curcumin and quercetin before radiation exposure.

The reduced number of nephrons with shortening renal tubules in mouse postnatal adverse environment

BACKGROUND

The intrauterine adverse environment during nephrogenesis reduces the nephron number, probably associates with impaired ureteric bud (UB) branching.

METHODS

The kidneys in C57/BL6 mice were irradiated with a single dose of 10 gray (10 Gy) as adverse environment on postnatal day 3 (irradiated PND3 kidneys) after UB branching ceased. The renal functions and pathological findings of irradiated PND3 kidneys were compared with those of non-irradiated control and 10 Gy irradiation on PND14 (irradiated PND14 kidney) from 1 to 18 months.

RESULTS

The number and density of glomeruli in irradiated PND3 kidneys were reduced by 1 month with renal dysfunction at 6 months. The morphologically incomplete glomeruli with insufficient capillaries were involuted by 1 month in the superficial cortex. Reduced tubular numbers and developmental disability with shortening renal tubules occurred in irradiated PND3 kidneys with impaired urine concentration at 6 months. Hypertrophy of glomeruli developed, and occasional sclerotic glomeruli appeared in the juxtamedullary cortex with hypertension and albuminuria at 12 to 18 months.

CONCLUSIONS

The reduced number of nephrons with shortening renal tubules occurred with impaired renal functions in a postnatal adverse environment after cessation of UB branching, and glomerular hypertrophy with occasional glomerulosclerosis developed accompanied with hypertension and albuminuria in the adulthood.

IMPACT

The reduced number of nephrons with shortening renal tubules occurred with impaired renal functions in a postnatal adverse environment after cessation of ureteric bud branching. The reduced number of glomeruli were associated with not only the impaired formation of glomeruli but also involution of morphologically small incomplete glomeruli after an adverse environment. The insufficiently developed nephrons were characterized by the shortening renal tubules with impaired urine concentration. In addition, glomerular hypertrophy and occasional glomerulosclerosis developed with hypertension and albuminuria in adulthood. The present study can help to understand the risk of alternations of premature nephrons in preterm neonates.

Radiation-induced FAP + fibroblasts are involved in keloid recurrence after radiotherapy

Background: Keloid scars (KSs), which are composed of abnormal hyperplastic scar tissue, form during skin wound healing due to excessive fibroblast activation and collagen secretion. Although surgical resection and radiation therapy are used to prevent recurrence, KS recurrence rates range from 15 to 23%, and the underlying mechanism is unclear.

Methods: To elucidate the mechanism of keloid recurrence, we established a PDX model and the grafts remained for over 20 weeks after transplantation on the bilateral backs of the NCG mice.

Results: RNA-seq revealed that KS tissue gene expression was highly consistent before and after transplantation. Then, one side of the KS graft was irradiated with electron beam therapy (10 Gy), significant increases in vimentin and fibroblast activation protein alpha (FAP) expression were observed after irradiation and were accompanied by severe microvascular destruction. Surprisingly, 4 weeks after irradiation, significantly increased recurrence was observed with increased FAP + tissue and cell cycle regulator expression, resulting in a remarkable altered graft volume. Moreover, irradiation-induced FAP upregulation markedly facilitated radiation resistance and increased cell cycle progression, decreased senescence, and increased energy production.

Conclusion: Our findings revealed that irradiation causes increased abundance of FAP + cells, which was associated with cell proliferation and delayed cellular senescence, accompanied by ATP production.

Estrogen receptor inhibition mediates radiosensitization of ER-positive breast cancer models

Endocrine therapy (ET) is an effective first-line therapy for women with estrogen receptor-positive (ER + ) breast cancers. While both ionizing radiation (RT) and ET are used for the treatment of women with ER+ breast cancer, the most effective sequencing of therapy and the effect of ET on tumor radiosensitization remains unclear. Here we sought to understand the effects of inhibiting estrogen receptor (ER) signaling in combination with RT in multiple preclinical ER+ breast cancer models. Clonogenic survival assays were performed using variable pre- and post-treatment conditions to assess radiosensitization with estradiol, estrogen deprivation, tamoxifen, fulvestrant, or AZD9496 in ER+ breast cancer cell lines. Estrogen stimulation was radioprotective (radiation enhancement ratios [rER]: 0.51–0.82). Conversely, when given one hour prior to RT, ER inhibition or estrogen depletion radiosensitized ER+ MCF-7 and T47D cells (tamoxifen rER: 1.50–1.60, fulvestrant rER: 1.76–2.81, AZD9496 rER: 1.33–1.48, estrogen depletion rER: 1.47–1.51). Combination treatment resulted in an increase in double-strand DNA (dsDNA) breaks as a result of inhibition of non-homologous end joining-mediated dsDNA break repair with no effect on homologous recombination. Treatment with tamoxifen or fulvestrant in combination with RT also increased the number of senescent cells but did not affect apoptosis or cell cycle distribution. Using an MCF-7 xenograft model, concurrent treatment with tamoxifen and RT was synergistic and resulted in a significant decrease in tumor volume and a delay in time to tumor doubling without significant toxicity. These findings provide preclinical evidence that concurrent treatment with ET and RT may be an effective radiosensitization strategy.

TGF-β1 is involved in senescence-related pathways in glomerular endothelial cells via p16 translocation and p21 induction

p16 inhibits cyclin-dependent kinases and regulates senescence-mediated arrest as well as p21. Nuclear p16 promotes G1 cell cycle arrest and cellular senescence. In various glomerular diseases, nuclear p16 expression is associated with disease progression. Therefore, the location of p16 is important. However, the mechanism of p16 trafficking between the nucleus and cytoplasm is yet to be fully investigated. TGF-β1, a major cytokine involved in the development of kidney diseases, can upregulate p21 expression. However, the relationship between TGF-β1 and p16 is poorly understood. Here, we report the role of podocyte TGF-β1 in regulating the p16 behavior in glomerular endothelial cells. We analyzed podocyte-specific TGF-β1 overexpression mice. Although p16 was found in the nuclei of glomerular endothelial cells and led to endothelial cellular senescence, the expression of p16 did not increase in glomeruli. In cultured endothelial cells, TGF-β1 induced nuclear translocation of p16 without increasing its expression. Among human glomerular diseases, p16 was detected in the nuclei of glomerular endothelial cells. In summary, we demonstrated the novel role of podocyte TGF-β1 in managing p16 behavior and cellular senescence in glomeruli, which has clinical relevance for the progression of human glomerular diseases.

DNA Damage-Induced Inflammatory Microenvironment and Adult Stem Cell Response

Adult stem cells ensure tissue homeostasis and regeneration after injury. Due to their longevity and functional requirements, throughout their life stem cells are subject to a significant amount of DNA damage. Genotoxic stress has recently been shown to trigger a cascade of cell- and non-cell autonomous inflammatory signaling pathways, leading to the release of pro-inflammatory factors and an increase in the amount of infiltrating immune cells. In this review, we discuss recent evidence of how DNA damage by affecting the microenvironment of stem cells present in adult tissues and neoplasms can affect their maintenance and long-term function. We first focus on the importance of self-DNA sensing in immunity activation, inflammation and secretion of pro-inflammatory factors mediated by activation of the cGAS-STING pathway, the ZBP1 pathogen sensor, the AIM2 and NLRP3 inflammasomes. Alongside cytosolic DNA, the emerging roles of cytosolic double-stranded RNA and mitochondrial DNA are discussed. The DNA damage response can also initiate mechanisms to limit division of damaged stem/progenitor cells by inducing a permanent state of cell cycle arrest, known as senescence. Persistent DNA damage triggers senescent cells to secrete senescence-associated secretory phenotype (SASP) factors, which can act as strong immune modulators. Altogether these DNA damage-mediated immunomodulatory responses have been shown to affect the homeostasis of tissue-specific stem cells leading to degenerative conditions. Conversely, the release of specific cytokines can also positively impact tissue-specific stem cell plasticity and regeneration in addition to enhancing the activity of cancer stem cells thereby driving tumor progression. Further mechanistic understanding of the DNA damage-induced immunomodulatory response on the stem cell microenvironment might shed light on age-related diseases and cancer, and potentially inform novel treatment strategies.

Age-dependent effects on radiation-induced carcinogenesis in the rat thyroid

Childhood radiation exposure is a known thyroid cancer risk factor. This study evaluated the effects of age on radiation-induced thyroid carcinogenesis in rats irradiated with 8 Gy X-rays. We analyzed cell proliferation, cell death, DNA damage response, and autophagy-related markers in 4-week-old (4W) and 7-month-old (7M) rats and the incidence of thyroid tumors in 4W, 4-month-old (4M), and 7M rats 18 months after irradiation. Cell death and DNA damage response were increased in 4W rats compared to those in controls at 1 month post-irradiation. More Ki-67-positive cells were observed in 4W rats at 12 months post-irradiation. Thyroid tumors were confirmed in 61.9% (13/21), 63.6% (7/11), and 33.3% (2/6) of irradiated 4W, 4M, and 7M rats, respectively, compared to 0%, 14.3% (1/7), and 16.7% (1/6) in the respective nonirradiated controls. There were 29, 9, and 2 tumors in irradiated 4W, 4M, and 7M rats, respectively. The expression of several autophagy components was downregulated in the area surrounding radiation-induced thyroid carcinomas in 4W and 7M rats. LC3 and p62 expression levels decreased in radiation-induced follicular carcinoma in 4W rats. Radiosensitive cells causing thyroid tumors may be more prevalent in young rats, and abrogation of autophagy may be associated with radiation-induced thyroid carcinogenesis.

Irradiation Accelerates Plaque Formation and Cellular Senescence in Flow-Altered Carotid Arteries of Apolipoprotein E Knock-Out Mice

Background

Chronic inflammation through cellular senescence, known as the senescence‐associated secretory phenotype, is a mechanism of various organ diseases, including atherosclerosis. Particularly, ionizing radiation (IR) contributes to cellular senescence by causing DNA damage. Although previous clinical studies have demonstrated that radiotherapy causes atherosclerosis as a long‐term side effect, the detailed mechanism is unclear. This study was conducted to investigate the relationship between radiation‐induced atherosclerosis and senescence‐associated secretory phenotype in murine carotid arteries.

Methods and Results

Partial ligation of the left carotid artery branches in 9‐week‐old male apolipoprotein E‐deficient mice was performed to induce atherosclerosis. The mice received total body irradiation at a dose of 6 Gy using gamma rays at 2 weeks post operation. We compared the samples collected 4 weeks after IR with unirradiated control samples. The IR and control groups presented pathologically progressive lesions in 90.9% and 72.3% of mice, respectively. Plaque volume, macrophage accumulation, and phenotype switching of vascular smooth muscle cells were advanced in the IR group. Irradiated samples showed increased persistent DNA damage response (53BP1 [p53 binding protein 1]), upregulated cyclin‐dependent kinase inhibitors (p16INK4a and p21), and elevated inflammatory chemokines expression (monocyte chemotactic protein‐1, keratinocyte‐derived chemokine, and macrophage inflammatory protein 2).

Conclusions

IR promoted plaque growth in murine carotid arteries. Our findings support the possibility that senescence‐associated secretory phenotype aggravates atherogenesis in irradiated artery. This mice model might contribute to mechanism elucidation of radiation‐induced atherosclerosis.

Vascular Endothelial Senescence: Pathobiological Insights, Emerging Long Noncoding RNA Targets, Challenges and Therapeutic Opportunities

Cellular senescence is a stable form of cell cycle arrest in response to various stressors. While it serves as an endogenous pro-resolving mechanism, detrimental effects ensue when it is dysregulated. In this review, we introduce recent advances for cellular senescence and inflammaging, the underlying mechanisms for the reduction of nicotinamide adenine dinucleotide in tissues during aging, new knowledge learned from p16 reporter mice, and the development of machine learning algorithms in cellular senescence. We focus on pathobiological insights underlying cellular senescence of the vascular endothelium, a critical interface between blood and all tissues. Common causes and hallmarks of endothelial senescence are highlighted as well as recent advances in endothelial senescence. The regulation of cellular senescence involves multiple mechanistic layers involving chromatin, DNA, RNA, and protein levels. New targets are discussed including the roles of long noncoding RNAs in regulating endothelial cellular senescence. Emerging small molecules are highlighted that have anti-aging or anti-senescence effects in age-related diseases and impact homeostatic control of the vascular endothelium. Lastly, challenges and future directions are discussed including heterogeneity of endothelial cells and endothelial senescence, senescent markers and detection of senescent endothelial cells, evolutionary differences for immune surveillance in mice and humans, and long noncoding RNAs as therapeutic targets in attenuating cellular senescence. Accumulating studies indicate that cellular senescence is reversible. A better understanding of endothelial cellular senescence through lifestyle and pharmacological interventions holds promise to foster a new frontier in the management of cardiovascular disease risk.

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Radiation-induced kidney toxicity: molecular and cellular pathogenesis

Radiation nephropathy (RN) is a kidney injury induced by ionizing radiation. In a clinical setting, ionizing radiation is used in radiotherapy (RT). The use and the intensity of radiation therapy is limited by normal-tissue damage including kidney toxicity. Different thresholds for kidney toxicity exist for different entities of RT. Histopathologic features of RN include vascular, glomerular and tubulointerstitial damage. The different molecular and cellular pathomechanisms involved in RN are not fully understood. Ionizing radiation causes double-stranded breaks in the DNA, followed by cell death including apoptosis and necrosis of renal endothelial, tubular and glomerular cells. Especially in the latent phase of RN oxidative stress and inflammation have been proposed as putative pathomechanisms, but so far no clear evidence was found. Cellular senescence, activation of the renin–angiotensin–aldosterone-system and vascular dysfunction might contribute to RN, but only limited data is available. Several signalling pathways have been identified in animal models of RN and different approaches to mitigate RN have been investigated. Drugs that attenuate cell death and inflammation or reduce oxidative stress and renal fibrosis were tested. Renin–angiotensin–aldosterone-system blockade, anti-apoptotic drugs, statins, and antioxidants have been shown to reduce the severity of RN. These results provide a rationale for the development of new strategies to prevent or reduce radiation-induced kidney toxicity.

Role of miRNAs in regulating responses to radiotherapy in human breast cancer

Breast cancer is the most common type of cancer that affects females globally. Radiotherapy is a standard treatment option for breast cancer, where one of its most significant limitations is radioresistance development. MicroRNAs (miRNAs) are small, non-protein-coding RNAs that have been widely studied for their roles as disease biomarkers. To date, several in vitro, in vivo, and clinical studies have reported the roles of miRNAs in regulating radiosensitivity and radioresistance in breast cancer cells. This article reviews the roles of miRNAs in regulating treatment response toward radiotherapy and the associating cellular pathways. We identified 36 miRNAs that play a role in mediating radio-responses; 22 were radiosensitizing, 12 were radioresistance-promoting, and two miRNAs were reported to promote both effects. A brief overview of breast cancer therapy options, mechanism of action of radiation, and molecular mechanism of radioresistance was provided in this article. A summary of the latest clinical researches involving miRNAs in breast cancer radiotherapy was also included.

Cellular Senescence in the Lung: The Central Role of Senescent Epithelial Cells

Cellular senescence is a key process in physiological dysfunction developing upon aging or following diverse stressors including ionizing radiation. It describes the state of a permanent cell cycle arrest, in which proliferating cells become resistant to growth-stimulating factors. Senescent cells differ from quiescent cells, which can re-enter the cell cycle and from finally differentiated cells: morphological and metabolic changes, restructuring of chromatin, changes in gene expressions and the appropriation of an inflammation-promoting phenotype, called the senescence-associated secretory phenotype (SASP), characterize cellular senescence. The biological role of senescence is complex, since both protective and harmful effects have been described for senescent cells. While initially described as a mechanism to avoid malignant transformation of damaged cells, senescence can even contribute to many age-related diseases, including cancer, tissue degeneration, and inflammatory diseases, particularly when senescent cells persist in damaged tissues. Due to overwhelming evidence about the important contribution of cellular senescence to the pathogenesis of different lung diseases, specific targeting of senescent cells or of pathology-promoting SASP factors has been suggested as a potential therapeutic approach. In this review, we summarize recent advances regarding the role of cellular (fibroblastic, endothelial, and epithelial) senescence in lung pathologies, with a focus on radiation-induced senescence. Among the different cells here, a central role of epithelial senescence is suggested.

Delayed effects of acute whole body lethal radiation exposure in mice pre-treated with BBT-059

The threat of nuclear exposure is heightened and it is imperative to identify potential countermeasures for acute radiation syndrome. Currently no countermeasures have been approved for prophylactic administration. Effective countermeasures should function to increase survival in the short term as well as to increase the overall prognosis of an exposed individual long term. Here we describe the use of a promising radiation countermeasure, BBT-059, and the results of a long term mouse study (up to 12 months) in the male CD2F1 strain using ⁶⁰Co gamma irradiation (~0.6 Gy/min, 7.5-12.5 Gy). We report the dose reduction factor of 1.28 for BBT-059 (0.3 mg/kg) compared to control administered 24 h prior to irradiation. In the long term study animals showed accelerated recovery in peripheral blood cell counts, bone marrow colony forming units, sternal cellularity and megakaryocyte numbers in drug treated mice compared to formulation buffer. In addition, increased senescence was observed in the kidneys of animals administered control or drug and exposed to the highest doses of radiation. Decreased levels of E-cadherin, LaminB1 and increased levels of Cyc-D and p21 in spleen lysates were observed in animals administered control. Taken together the results indicate a high level of protection following BBT-059 administration in mice exposed to lethal and supralethal doses of total body gamma-radiation.

Transplanted senescent renal scattered tubular-like cells induce injury in the mouse kidney

Cellular senescence, a permanent arrest of cell proliferation, is characterized by a senescence-associated secretory phenotype (SASP), which reinforces senescence and exerts noxious effects on adjacent cells. Recent studies have suggested that transplanting small numbers of senescent cells suffices to provoke tissue inflammation. We hypothesized that senescent cells can directly augment renal injury. Primary scattered tubular-like cells (STCs) acquired from pig kidneys were irradiated by 10 Gy of cesium radiation, and 3 wk later cells were characterized for levels of senescence and SASP markers. Control or senescent STCs were then prelabeled and injected (5 × 10⁵ cells) into the aorta of C57BL/6J mice. Four weeks later, renal oxygenation was studied in vivo using 16.4-T magnetic resonance imaging and function by plasma creatinine level. Renal markers of SASP, fibrosis, and microvascular density were evaluated ex vivo. Per flow cytometry, irradiation induced senescence in 80-99% of STCs, which showed increased gene expression of senescence and SASP markers, senescence-associated β-galactosidase staining, and cytokine levels (especially IL-6) secreted in conditioned medium. Four weeks after injection, cells were detected engrafted in the mouse kidneys with no evidence for rejection. Plasma creatinine and renal tissue hypoxia increased in senescent compared with control cells. Senescent kidneys were more fibrotic, with fewer CD31⁺ endothelial cells, and showed upregulation of IL-6 gene expression. Therefore, exogenously delivered senescent renal STCs directly injure healthy mouse kidneys. Additional studies are needed to determine the role of endogenous cellular senescence in the pathogenesis of kidney injury and evaluate the utility of senolytic therapy.

Chronic Kidney Disease: A Vicarious Relation to Premature Cell Senescence

Chronic kidney disease (CKD), commonly fostering nonrenal complications, themselves more life threatening than renal pathology, remains enigmatic. Despite more than a century of intense research, therapeutic options to halt or reverse renal disease are rather limited. Recently, similarity between manifestations of progressive CKD and aging kidney has attracted investigative attention that revealed senescent cells and secreting proinflammatory and profibrotic mediators in all renal compartments, even at young age, in patients with kidney maladies. The overlapping features of these categories have been noticed previously and are briefly summarized herein. I propose two hypothetical scenarios for interactive association of kidney diseases and cell senescence, both culminating in progressive deterioration of renal function. Persistence of senescent cells is considered as a critical contributor to this association; and the mechanisms explaining persistence, such as activation of cell cycle regulators, anti-apoptotic stimuli, metabolic aberrations, and their interactions, are discussed. The mutual encroachment of underlying kidney disease and cell senescence bring about the conclusion that both entities merge along the natural history of the disease. This putative interpretation of vicarious relation between cell senescence and CKD may expand the arsenal of pharmacotherapy to include the judicious use of senotherapeutics in the management of renal disease.