Klotho supplementation ameliorates blood pressure and renal function in DBA/2-pcy mice, a model of polycystic kidney disease

Klotho inhibits IGF1R/PI3K/AKT signalling pathway and protects the heart from oxidative stress during ischemia/reperfusion injury

Ischemia/reperfusion injury (IRI) of the heart involves the activation of oxidative and proapoptotic pathways. Simultaneously Klotho protein presents anti-aging, antiapoptotic and antioxidative properties. Therefore, this study aimed to evaluate the effect of Klotho protein on oxidative stress in hearts subjected to IRI. Isolated rat hearts perfused with the Langendorff method were subjected to ischemia, followed by reperfusion, in the presence or absence of recombinant rat Klotho protein. The factors involved in the activation of insulin-like growth factor receptor (IGF1R)/phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signalling pathway were evaluated. IRI caused activation of the IGF1R (p = 0.0122)/PI3K (p = 0.0022) signalling, as compared to the aerobic control group. Infusion supply of Klotho protein during IRI significantly reduced the level of phospho-IGF1R (p = 0.0436), PI3K (p = 0.0218) and phospho-AKT (p = 0.0020). Transcriptional activity of forkhead box protein O3 (FOXO3) was reduced (p = 0.0207) in hearts subjected to IRI, compared to aerobic control. Administration of Klotho decreased phosphorylation of FOXO3 (p = 0.0355), and enhanced activity of glutathione peroxidase (p = 0.0452) and superoxide dismutase (p = 0.0060) in IRI + Klotho group. The levels of reactive oxygen/nitrogen species (ROS/RNS) (p = 0.0480) and hydrogen peroxide (H2O2) (p = 0.0460), and heart injury (p = 0.0005) were significantly increased in hearts from the IRI group in comparison to the aerobic group. Klotho reduced NADPH oxidase 2 (NOX2) (p = 0.0390), ROS/RNS (p = 0.0435) and H2O2 (p = 0.0392) levels, and heart damage (p = 0.0286) in the hearts subjected to IRI. In conclusion, Klotho contributed to the protection of the heart against IRI and oxidative stress via inhibition of the IGF1R/PI3K/AKT pathway, thus can be recognized as a novel cardiopreventive/cardioprotective agent.

Degradation of histone deacetylase 6 alleviates ROS-mediated apoptosis in renal ischemia-reperfusion injury

Renal ischemia reperfusion injury (RIRI) is an inevitable complication during renal surgery. Histone deacetylase 6 (HDAC6), a key member of the histone deacetylase family, is associated with multiple pathologies, including renal diseases. However, whether HDAC6 could become a potential therapeutic target for clinical application of RIRI remained to be proven. Here, we found that HDAC6 expression was abnormally enhanced by the transcription factor OSR2 in RIRI. Moreover, we were the first to validate that a selective HDAC6 degrader, proteolysis-targeting chimeras (PROTAC) NP8, could significantly improve RIRI. Further in vivo and in vitro mechanism studies have found that the reduction of HDAC6 alleviated RIRI by inhibiting ROS mediated apoptosis. Remarkably, a renal protective protein, Klotho, has been proven to be a target of HDAC6, and the degradation of HDAC6 restored KL expression, thereby ameliorating ROS mediated apoptosis. Overall, our results illustrated that the degradation of HDAC6 restrained ROS mediated apoptosis by restoring Klotho expression during RIRI. PROTAC-NP8 might be a potential therapeutic strategy for clinical prevention of RIRI.

Klotho Supplementation Reverses Renal Dysfunction and Interstitial Fibrosis in Remnant Kidney

INTRODUCTION

While recent investigations show that klotho exerts renoprotective actions, it has not been fully addressed whether klotho protein supplementation reverses renal damage.

METHODS

The impacts of subcutaneous klotho supplementation on rats with subtotal nephrectomy were examined. Animals were divided into 3 groups: group 1 (short remnant [SR]): remnant kidney for 4 weeks, group 2 (long remnant [LR]): remnant kidney for 12 weeks, and group 3 (klotho supplementation [KL]): klotho protein (20 μg/kg/day) supplementation on the remnant kidney. Blood pressure, blood and urine compositions with conventional methods such as enzyme-linked immunosorbent assay and radioimmunoassay, kidney histology, and renal expressions of various genes were analyzed. In vitro studies were also performed to support in vivo findings.

RESULTS

Klotho protein supplementation decreased albuminuria (-43%), systolic blood pressure (-16%), fibroblast growth factor (FGF) 23 (-51%) and serum phosphate levels (-19%), renal angiotensin II concentration (-43%), fibrosis index (-70%), renal expressions of collagen I (-55%), and transforming growth factor β (-59%) (p < 0.05 for all). Klotho supplementation enhanced fractional excretion of phosphate (+45%), glomerular filtration rate (+76%), renal expressions of klotho (+148%), superoxide dismutase (+124%), and bone morphogenetic protein (BMP) 7 (+174%) (p < 0.05 for all).

CONCLUSION

Our data indicated that klotho protein supplementation inactivated renal renin-angiotensin system, reducing blood pressure and albuminuria in remnant kidney. Furthermore, exogenous klotho protein supplementation elevated endogenous klotho expression to increase phosphate excretion with resultant reductions in FGF23 and serum phosphate. Finally, klotho supplementation reversed renal dysfunction and fibrosis in association with improved BMP7 in remnant kidney.

Review of the Use of Animal Models of Human Polycystic Kidney Disease for the Evaluation of Experimental Therapeutic Modalities

Autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, and nephronophthisis are hereditary disorders with the occurrence of numerous cysts in both kidneys, often causing chronic and end-stage renal failure. Animal models have played an important role in recent advances in research not only on disease onset and progressive mechanisms but also on the development of therapeutic interventions. For a long time, spontaneous animal models have been used as the primary focus for human diseases; however, after the identification of the nucleotide sequence of the responsible genes, PKD1, PKD2, PKHD1, and NPHPs, various types of genetically modified models were developed by genetic and reproductive engineering techniques and played the leading role in the research field. In this review, we present murine models of hereditary renal cystic diseases, discussing their potential benefits in the development of therapeutic strategies.

A systematic review and meta-analysis demonstrating Klotho as an emerging exerkine

Klotho is an anti-aging protein with several therapeutic roles in the pathophysiology of different organs, such as the skeletal muscle and kidneys. Available evidence suggests that exercise increases Klotho levels, regardless of the condition or intervention, shedding some light on this anti-aging protein as an emergent and promising exerkine. Development of a systematic review and meta-analysis in order to verify the role of different exercise training protocols on the levels of circulating soluble Klotho (S-Klotho) protein. A systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE through PubMed, EMBASE, CINAHL, CT.gov, and PEDro. Randomized and quasi-randomized controlled trials that investigated effects of exercise training on S-Klotho levels. We included 12 reports in the analysis, comprising 621 participants with age ranging from 30 to 65 years old. Klotho concentration increased significantly after chronic exercise training (minimum of 12 weeks) (Hedge' g [95%CI] 1.3 [0.69-1.90]; P < 0.0001). Moreover, exercise training increases S-Klotho values regardless of the health condition of the individual or the exercise intervention, with the exception of combined aerobic + resistance training. Furthermore, protocol duration and volume seem to influence S-Klotho concentration, since the effect of the meta-analysis changes when subgrouping these variables. Altogether, circulating S-Klotho protein is altered after chronic exercise training and it might be considered an exerkine. However, this effect may be influenced by different training configurations, including protocol duration, volume, and intensity.

Pathophysiology and genetics of salt-sensitive hypertension

Most hypertensive cases are primary and heavily associated with modifiable risk factors like salt intake. Evidence suggests that even small reductions in salt consumption reduce blood pressure in all age groups. In that regard, the ACC/AHA described a distinct set of individuals who exhibit salt-sensitivity, regardless of their hypertensive status. Data has shown that salt-sensitivity is an independent risk factor for cardiovascular events and mortality. However, despite extensive research, the pathogenesis of salt-sensitive hypertension is still unclear and tremendously challenged by its multifactorial etiology, complicated genetic influences, and the unavailability of a diagnostic tool. So far, the important roles of the renin-angiotensin-aldosterone system, sympathetic nervous system, and immune system in the pathogenesis of salt-sensitive hypertension have been studied. In the first part of this review, we focus on how the systems mentioned above are aberrantly regulated in salt-sensitive hypertension. We follow this with an emphasis on genetic variants in those systems that are associated with and/or increase predisposition to salt-sensitivity in humans.

Pathobiology of the Klotho Antiaging Protein and Therapeutic Considerations

The α-Klotho protein (henceforth denoted Klotho) has antiaging properties, as first observed in mice homozygous for a hypomorphic Klotho gene (kl/kl). These mice have a shortened lifespan, stunted growth, renal disease, hyperphosphatemia, hypercalcemia, vascular calcification, cardiac hypertrophy, hypertension, pulmonary disease, cognitive impairment, multi-organ atrophy and fibrosis. Overexpression of Klotho has opposite effects, extending lifespan. In humans, Klotho levels decline with age, chronic kidney disease, diabetes, Alzheimer’s disease and other conditions. Low Klotho levels correlate with an increase in the death rate from all causes. Klotho acts either as an obligate coreceptor for fibroblast growth factor 23 (FGF23), or as a soluble pleiotropic endocrine hormone (s-Klotho). It is mainly produced in the kidneys, but also in the brain, pancreas and other tissues. On renal tubular-cell membranes, it associates with FGF receptors to bind FGF23. Produced in bones, FGF23 regulates renal excretion of phosphate (phosphaturic effect) and vitamin D metabolism. Lack of Klotho or FGF23 results in hyperphosphatemia and hypervitaminosis D. With age, human renal function often deteriorates, lowering Klotho levels. This appears to promote age-related pathology. Remarkably, Klotho inhibits four pathways that have been linked to aging in various ways: Transforming growth factor β (TGF-β), insulin-like growth factor 1 (IGF-1), Wnt and NF-κB. These can induce cellular senescence, apoptosis, inflammation, immune dysfunction, fibrosis and neoplasia. Furthermore, Klotho increases cell-protective antioxidant enzymes through Nrf2 and FoxO. In accord, preclinical Klotho therapy ameliorated renal, cardiovascular, diabetes-related and neurodegenerative diseases, as well as cancer. s-Klotho protein injection was effective, but requires further investigation. Several drugs enhance circulating Klotho levels, and some cross the blood-brain barrier to potentially act in the brain. In clinical trials, increased Klotho was noted with renin-angiotensin system inhibitors (losartan, valsartan), a statin (fluvastatin), mTOR inhibitors (rapamycin, everolimus), vitamin D and pentoxifylline. In preclinical work, antidiabetic drugs (metformin, GLP-1-based, GABA, PPAR-γ agonists) also enhanced Klotho. Several traditional medicines and/or nutraceuticals increased Klotho in rodents, including astaxanthin, curcumin, ginseng, ligustilide and resveratrol. Notably, exercise and sport activity increased Klotho. This review addresses molecular, physiological and therapeutic aspects of Klotho.

CCL5 Suppresses Klotho Expression via p-STAT3/DNA Methyltransferase1-Mediated Promoter Hypermethylation

Background

Enhanced inflammation and reduced Klotho are common features in chronic kidney disease (CKD). Inflammation induces DNA hypermethylation. This study assessed the performance of inflammatory marker C-C motif chemokine 5 (CCL5) in epigenetic regulation of Klotho expression.

Methods

Fifty CKD patients and 25 matched controls were enrolled, and serum CCL5 level, sKlotho level, and DNA methylation were evaluated in these subjects. A renal interstitial fibrosis (RIF) model with CKD was induced in mice via unilateral ureteral obstruction (UUO) in vivo and human proximal tubular epithelial (HK-2) cells treated with CCL5 in vitro. 5-aza-2′-deoxycytidine (5-Aza), a DNA methyltransferase inhibitor was given to UUO mice. Hematoxylin and eosin (HE) and Masson trichrome staining were adopted to evaluate renal pathological changes. Methylation-specific PCR was performed to assess DNA methylation of Klotho promoter in the peripheral blood leucocytes (PBLs) from CKD patients and obstructive kidney from UUO mice. CCL5, Klotho, and DNA methyltransferases (DNMTs) were determined by ELISAs, immunofluorescence, or western blotting. HK-2 cells were exposed to CCL5 with or without 5-Aza and stattic, a p-signal transducer and activator of transcription 3 (STAT3) inhibitor, and expressions of p-STAT3, DNMT1, and Klotho were determined by western blotting.

Results

CCL5 upregulation concomitant with Klotho downregulation in serum and global DNA methylation in PBLs were observed in CKD samples. UUO contributed to severe renal interstitial fibrosis and enhanced expressions of fibrotic markers. Moreover, UUO increased the CCL5 level, induced Klotho promoter methylation, suppressed Klotho level, activated p-STAT3 signaling, and upregulated DNMT1 level. A similar observation was made in HK-2 cells treated with CCL5. More importantly, 5-Aza inhibited UUO-induced Klotho hypermethylation, reversed Klotho, downregulated p-STAT3 expressions, and ameliorated RIF in vivo. The consistent findings in vitro were also obtained in HK-2 cells exposed to 5-Aza and stattic.

Conclusion

The CCL5/p-STAT3/DNMT1 axis is implicated in epigenetic regulation of Klotho expression in CKD. This study provides novel therapeutic possibilities for reversal of Klotho suppression by CKD.

Klotho in kidney diseases: A crosstalk between the renin-angiotensin system and endoplasmic reticulum stress

Klotho is a transmembrane anti-ageing protein that exists in three forms, i.e., α-Klotho, β-Klotho, and γ-Klotho with distinct organ-specific expression and functions in the body. Here we focus on α-Klotho (mentioned as 'Klotho' only), abundantly expressed by the distal and proximal convoluted tubules of the kidney. Significant decline in systemic and renal Klotho level is a new hallmark for kidney disease progression. Emerging research portrays Klotho as a promising diagnostic as well as a therapeutic target for diabetic and non-diabetic kidney disease. Even so, the underlying mechanisms of Klotho regulation and the strategies to restore its systemic as well as the renal level are still lacking. Angiotensin-converting enzyme inhibitors (ACEi) and/or angiotensin receptor blockers (ARBs) are the current standard of care for kidney diseases where the molecular mechanisms for their nephroprotective action are still ambiguous. Moreover, endoplasmic reticulum stress (ER stress) also plays a crucial role in kidney disease progression. Few studies have claimed that RAAS has a direct relation with ER stress generation and vice versa in kidney disease. Interestingly, RAAS and ER stress modulation is associated with Klotho regulation in kidney disease. Here we focus on how the RAAS and ER stress connects with Klotho regulation in kidney disease. We also discuss Klotho and ER stress in an alliance with the concept of hemodynamic and metabolic overload in kidney disease. In addition, we highlight novel approaches to implement Klotho as a therapeutic target via RAAS and ER stress modulation for the treatment of diabetic and non-diabetic kidney disease.

Insights Into the Molecular Mechanisms of Polycystic Kidney Diseases

Autosomal dominant (AD) and autosomal recessive (AR) polycystic kidney diseases (PKD) are severe multisystem genetic disorders characterized with formation and uncontrolled growth of fluid-filled cysts in the kidney, the spread of which eventually leads to the loss of renal function. Currently, there are no treatments for ARPKD, and tolvaptan is the only FDA-approved drug that alleviates the symptoms of ADPKD. However, tolvaptan has only a modest effect on disease progression, and its long-term use is associated with many side effects. Therefore, there is still a pressing need to better understand the fundamental mechanisms behind PKD development. This review highlights current knowledge about the fundamental aspects of PKD development (with a focus on ADPKD) including the PC1/PC2 pathways and cilia-associated mechanisms, major molecular cascades related to metabolism, mitochondrial bioenergetics, and systemic responses (hormonal status, levels of growth factors, immune system, and microbiome) that affect its progression. In addition, we discuss new information regarding non-pharmacological therapies, such as dietary restrictions, which can potentially alleviate PKD.

Limitations and opportunities in the pharmacotherapy of ciliopathies

Ciliopathies are a family of rather diverse conditions, which have been grouped based on the finding of altered or dysfunctional cilia, potentially motile, small cellular antennae extending from the surface of postmitotic cells. Cilia-related disorders include embryonically arising conditions such as Joubert, Usher or Kartagener syndrome, but also afflictions with a postnatal or even adult onset phenotype, i.e. autosomal dominant polycystic kidney disease. The majority of ciliopathies are syndromic rather than affecting only a single organ due to cilia being found on almost any cell in the human body. Overall ciliopathies are considered rare diseases. Despite that, pharmacological research and the strive to help these patients has led to enormous therapeutic advances in the last decade. In this review we discuss new treatment options for certain ciliopathies, give an outlook on promising future therapeutic strategies, but also highlight the limitations in the development of therapeutic approaches of ciliopathies.

Klotho supplementation attenuates blood pressure and albuminuria in murine model of IgA nephropathy

BACKGROUND

Klotho interacts with various membrane proteins, such as transforming growth factor-β (TGFβ) and insulin-like growth factor (IGF) receptors. The renal expression of klotho is diminished in chronic kidney disease.

METHOD

In this study, we assessed the effects of klotho supplementation on a murine model of IgA nephropathy. Twenty-four-week-old hyper serum IgA (HIGA) mice were subcutaneously injected daily with recombinant human klotho protein (20 μg/kg per day) or the vehicle. After 2 months, the mice were killed using an anesthesia overdose and their kidneys were harvested for analysis.

RESULTS

Supplementation of exogenous klotho protein reduced SBP, albuminuria, 8-epi-prostaglandin F2α excretion, glomerular filtration rate, renal angiotensin II concentration, and angiotensinogen expression in HIGA mice. Additionally, it enhanced renal expression of superoxide dismutase (SOD) and renal klotho itself. The findings using laser-manipulated microdissection demonstrated that klotho supplementation reduced the glomerular expression of TGFβ, fibronectin, and IGF, and increased the glomerular expression of connexin (Cx) 40.

CONCLUSION

These results indicate that klotho supplementation reduces blood pressure by suppressing the renin--angiotensin system in HIGA mice. Klotho inhibits IGF signaling to preserve glomerular Cx40 levels, ameliorating albuminuria in HIGA mice. Klotho protein supplementation attenuates mesangial expansion by inhibiting TGFβ signaling in HIGA mice.

Role of Klotho in the Development of Essential Hypertension

Klotho has antiaging properties, and serum levels decrease with physiological aging and aging-related diseases, such as hypertension, cardiovascular, and chronic kidney disease. Klotho deficiency in mice results in accelerated aging and cardiovascular injury, whereas Klotho supplementation slows down the progression of aging-related diseases. The pleiotropic functions of Klotho include, but are not limited to, inhibition of insulin/IGF-1 (insulin-like growth factor 1) and WNT (wingless-related integration site) signaling pathways, suppression of oxidative stress and aldosterone secretion, regulation of calcium-phosphate homeostasis, and modulation of autophagy with inhibition of apoptosis, fibrosis, and cell senescence. Accumulating evidence shows an interconnection between Klotho deficiency and hypertension, and Klotho gene polymorphisms are associated with hypertension in humans. In this review, we critically review the current understanding of the role of Klotho in the development of essential hypertension and the most important underlying pathways involved, such as the FGF23 (fibroblast growth factor 23)/Klotho axis, aldosterone, Wnt5a/RhoA, and SIRT1 (Sirtuin1). Based on this critical review, we suggest avenues for further research.

Blood Flow Restriction Training Blunts Chronic Kidney Disease Progression in Humans

PURPOSE

This study aimed to verify the effect of 6 months of periodized resistance training (RT) with and without blood flow restriction (BFR) in patients with stage 2 chronic kidney disease (CKD) on glomerular filtration rate (GFR), uremic parameters, cytokines, and klotho-fibroblast growth factor 23 (FGF23) axis.

METHODS

A total of 105 subjects were randomized in three groups of 35 each: control (CTL), RT, and RT + BFR. A first visit was required for an anamnesis to evaluate the number of medications and anthropometric measurements (body weight, height, and body mass index). Muscle strength (one-repetition maximum) was assessed. Venous blood samples were collected at baseline and after 6 months of training in all patients for the analysis of markers of renal function and integrity, as well as for the determination of the inflammatory profile. Statistical significances were adopted with P < 0.05.

RESULTS

Both training therapies attenuated the decline of GFR (P < 0.05). The majority of CTL patients declined to stage 3 CKD (88.5%), whereas fewer incidents were noted with RT (25.7%) and RT + BFR (17.1%). Improved uremic parameters as well as inflammation (IL-6, IL-10, IL-15, IL-17a, IL-18, and TNF-α) and klotho-FGF23 axis in RT and RT + BFR (P < 0.05) were observed. Monocyte chemoattractant protein 1 was not changed (P > 0.05) but presented a large effect size (Cohen's d), demonstrating a propensity for improvement.

CONCLUSION

Six months of periodized RT with and without BFR in patients with stage 2 CKD attenuated the progression of the disease by maintaining GFR, improving uremic parameters, cytokine profile regulation, and klotho-FGF23 axis.

Histone deacetylase 3 aberration inhibits Klotho transcription and promotes renal fibrosis

Development of renal fibrosis is a hallmark of renal aging and chronic kidney disease of all etiologies and characterized by extensive renal cell injuries and subsequent myofibroblast transdifferentiations (MTDs), which are significantly influenced by aberrant histone deacetylase (HDAC) activities. However, the key HDAC isoforms and effectors that are causally involved in the processes remain poorly understood. Here, we report that aberrant HDAC3 induction and its inhibition of Klotho, a renal epithelium-enriched aging suppressor, contribute significantly to renal fibrogenesis. HDAC3 was preferentially elevated with concomitant Klotho suppression in fibrotic kidneys incurred by unilateral ureter obstruction (UUO) and aristolochic acid nephropathy (AAN), whereas Hdac3 knockout resisted the fibrotic pathologies. The HDAC3 elevation is substantially blocked by the inhibitors of TGFβ receptor and Smad3 phosphorylation, suggesting that TGFβ/Smad signal activates Hdac3 transcription. Consistently, an HDAC3-selective inhibitor RGFP966 derepressed Klotho and mitigated the renal fibrotic injuries in both UUO and AAN mice. Further, HDAC3 overexpression or inhibition in renal epithelia inversely affected Klotho abundances and HDAC3 was inducibly associated with transcription regulators NCoR and NF-kB and bound to Klotho promoter in fibrotic kidney, supporting that aberrant HDAC3 targets and transcriptionally inhibits Klotho under renal fibrotic conditions. More importantly, the antirenal fibrosis effects of RGFP966 were largely compromised in mice with siRNA-mediated Klotho knockdown. Hence, HDAC3 aberration and the subsequent Klotho suppression constitute an important regulatory loop that promotes MTD and renal fibrosis and uses of HDAC3-selective inhibitors are potentially effective in treating renal fibrotic disorders.

The Protective Role of Klotho in CKD-Associated Cardiovascular Disease

Background

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality in advanced CKD. The major pathological changes of CKD-associated CVD are severe vascular media calcification, aberrant cardiac remodeling such as hypertrophy and fibrosis, as well as accelerated atherosclerosis. α-Klotho is proposed as an anti-aging gene, which is primarily expressed in the kidney. Recent studies reveal that α-Klotho deficiency is associated with profound cardiovascular dysfunction. Of note, CKD represents extremely declined α-Klotho levels, hinting that α-Klotho deficiency may be implicated in the pathogenesis of CKD-associated CVD.

Summary

Based on the pathogenic mechanism of α-Klotho deficiency and decreased Klotho levels in the circulation even early in stage 1 of CKD, α-Klotho serves as a sensitive biomarker for renal insufficiency and also a novel predictor of risk of overall mortality of CVD events in CKD. Meanwhile, loss of Klotho resulted from kidney dysfunction markedly contributes to the progressive development of CKD and CVD. By contrast, prevention of Klotho decline using exogenous supplementation or genetically activated ways by several mechanisms can dramatically mitigate cardiac dysfunction, prevent vascular calcification, and retard the progression of CKD-accelerated atherosclerosis.

Key Messages

Klotho deficiency is proposed as a novel predictive biomarker as well as a pathogenic contributor to CVD events in CKD. In the future, Klotho may be a crucial potential therapeutic strategy to decrease the burden of CVD comorbidity with CKD in clinics.

Molecular Mechanisms of AKI in the Elderly: From Animal Models to Therapeutic Intervention

Acute kidney injury (AKI), a critical syndrome characterized by a sudden reduction of renal function, is a common disorder among elderly patients particularly in Intensive Care Unit (ICU). AKI is closely associated with both short- and long-term mortality and length of hospital stay and is considered a predictor of chronic kidney disease (CKD). Specific hemodynamic, metabolic, and molecular changes lead to increased susceptibility to injury in the aged kidney; therefore, certain causes of AKI such as the prerenal reduction in renal perfusion or vascular obstructive conditions are more common in the elderly; moreover, AKI is often multifactorial and iatrogenic. Older patients present several comorbidities (diabetes, hypertension, heart failure) and are exposed to multiple medical interventions such as the use of nephrotoxic contrasts media and medications, which can also trigger AKI. Considering the emerging relevance of this condition, prevention and treatment of AKI in the elderly should be crucial in the internist and emergency setting. This review article summarizes the incidence, the risk factors, the pathophysiology, the molecular mechanisms and the strategies of prevention and treatment of AKI in elderly patients.

P2X7 siRNA targeted to the kidneys increases klotho and delays the progression of experimental diabetic nephropathy

Previous studies in our laboratory have suggested that P2X7 could contribute to the progression of diabetic nephropathy and modulated klotho expression. The aim of this study was to investigate if P2X7 receptor is related to the expression of klotho in the onset of diabetic nephropathy in rats. Seven-week-old male Wistar rats weighing 210 g were all uninephrectomized; two-third of the animals were induced to diabetes with 60 mg/kg streptozotocin i.v., and one-third received its vehicle (control rats). At 4th day of the fifth week of the protocol, half of the diabetic rats received a small interfering RNA targeting for P2X7 mRNA, and the other half received its vehicle. Euthanasia was made at the eighth week. Diabetic animals reproduced all classic symptoms of the disease; besides, they showed reduced renal function and low NO bioavailability; also, SOD1, SOD2, and catalase were increased, probably due to the oxidative stress which was elevated in this situation. Metabolic data of diabetic rats did not change by silencing P2X7 receptor. For the other hand, silencing P2X7 was able to contribute to balance oxidative and nitrosative profile, ultimately improving the renal function and increasing plasma and membrane forms of klotho. These findings suggest that the management of P2X7 receptor can benefit the kidneys with diabetic nephropathy. Further studies are needed to show the therapeutic potential of this receptor inhibition to provide a better quality of life for the diabetic patient.