Inflammation and premature aging in advanced chronic kidney disease

Association between Nrf2 and CDKN2A expression in patients with end-stage renal disease: a pilot study

Patients with end-stage renal disease (ESRD) display phenotypic features of premature biological aging, characterized by disproportionately high morbidity and mortality at a younger age. Nuclear factor erythroid 2-related factor 2 (Nrf2) activity, a master regulator of antioxidative responses, declines with age and is implicated in the pathogenesis of age-related disorders; however, little is known about the association between Nrf2 and premature biological aging in ESRD patients. In a cross-sectional pilot cohort of 34 ESRD patients receiving maintenance hemodialysis, we measured the expression of Nrf2 and cyclin-dependent kinase inhibitor 2A (CDKN2A, or p16^INK4a, a biomarker of biological aging) genes in whole blood and examined the association of Nrf2 with CDKN2A expression, using Spearman's rank correlation and multivariable linear regression models with adjustment for potential confounders. There was a significant negative correlation between Nrf2 and CDKN2A expression (rho=-0.51, P=0.002); while no significant correlation was found between Nrf2 expression and chronological age (rho=-0.02, P=0.91). After multivariable adjustment, Nrf2 expression remained significantly and negatively associated with CDKN2A expression (β coefficient=-1.51, P=0.01), independent of chronological age, gender, race, and diabetes status. These findings suggest a potential contribution of Nrf2 dysfunction to the development of premature biological aging and its related morbidities in ESRD patients.

Long Non-Coding RNA (LncRNA)-ATB Promotes Inflammation, Cell Apoptosis and Senescence in Transforming Growth Factor-β1 (TGF-β1) Induced Human Kidney 2 (HK-2) Cells via TGFβ/SMAD2/3 Signaling Pathway

Background

Renal fibrosis occurs in the end-stage of all chronic kidney disease. Transforming growth factor-β1 (TGF-β1) is a central contributor in fibrosis. Identifying effective biomarkers that targets TGF-β1 is necessary for the development of therapeutic agents for kidney disease. In this study, we investigated the effects and mechanism of long non-coding RNA (LncRNA)-ATB in TGF-β1 induced human kidney 2 (HK-2) cells.

Material/Methods

We investigated the effects of either overexpression or knockdown of LncRNA-ATB on inflammation, cell apoptosis, and senescence in TGF-β1 induced HK-2 cells. TGF-β1 induced HK-2 cells served as the cell model. The gene level was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and protein expressions by western blot. Cell Counting Kit-8 (CCK-8) assay was performed for assessment of cell viability. Flow cytometry was applied for detection of cell apoptosis. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were measured by corresponding kits.

Results

LncRNA-ATB was highly expressed in TGF-β1 induced HK-2 cells. Inflammation, cell apoptosis, and senescence were enhanced by TGF-β1 and these effects were all reduced by knockdown of LncRNA-ATB. Whereas overexpression of LncRNA-ATB had the opposite effects with knockdown of LncRNA-ATB. The TGFβ/SMAD2/3 signaling pathway was activated by TGF-β1 and this effect was further enhanced by LncRNA-ATB overexpression. Silencing LncRNA-ATB inhibited the TGFβ/SMAD2/3 signaling pathway in TGF-β1 induced cells. The effects of LncRNA-ATB overexpression aforementioned in TGF-β1 induced cells were abolished by blockage of the TGFβ/S0MAD2/3 signaling pathway.

Conclusions

LncRNA-ATB overexpression have promoting effects on inflammation, cell apoptosis and senescence in TGF-β1 induced HK-2 cells via activating the TGFβ/SMAD2/3 signaling pathway. LncRNA-ATB act as a key downstream mediator via activating the TGFβ/SMAD2/3 signaling pathway and silencing LncRNA-ATB might be a new strategy for chronic kidney disease treatment.

Incorporating the Clinical Frailty Scale into routine outpatient nephrology practice: an observational study of feasibility and associations

BACKGROUND

There is an unmet need for routine and accurate prognostication of older adults with end-stage kidney disease (ESKD) and subsequently inadequate advance care planning. Frailty, a clinical syndrome of increased vulnerability, is predictive of adverse health outcomes in the renal population. We propose the Clinical Frailty Scale (CFS) as a feasible tool for routine use in the nephrology outpatient setting to address this unmet need.

AIMS

To assess feasibility and associations of incorporating CFS assessment into routine outpatient nephrology practice in the pre-dialysis setting.

METHODS

CFS was integrated into the outpatient nephrology clinic proforma. A convenience sample of 138 patients aged >50 years, with estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m² , attending the outpatient service between September 2018 and April 2019 was included.

RESULTS

Eighty-one CFS assessments were completed by nephrologists, nephrology advanced trainees and clinical nurse specialists. CFS completion rates were 79% from the multidisciplinary Low Clearance Clinic and 41% from nurse-led Pre-dialysis Education Clinic. Planned modality of ESKD management varied with degree of frailty (P < 0.001). 21% of patients who had CFS completed were planned for Conservative Management of ESKD, in contrast to only 5% of those who did not have CFS assessment completed (P < 0.001).

CONCLUSION

Frailty assessment via CFS was feasible in outpatient practice when integrated into routine clinical assessment in a dedicated clinic. Planned ESKD management varied with the degree of frailty. Completion of frailty assessment, when compared with non-completion, appears to be associated with increased planned conservative management of ESKD.

Molecular Mechanisms of Premature Aging in Hemodialysis: The Complex Interplay Between Innate and Adaptive Immune Dysfunction

Hemodialysis (HD) patient are known to be susceptible to a wide range of early and long-term complication such as chronic inflammation, infections, malnutrition, and cardiovascular disease that significantly affect the incidence of mortality. A large gap between the number of people with end-stage kidney disease (ESKD) and patients who received kidney transplantation has been identified. Therefore, there is a huge need to explore the underlying pathophysiology of HD complications in order to provide treatment guidelines. The immunological dysregulation, involving both the innate and adaptive response, plays a crucial role during the HD sessions and in chronic, maintenance treatments. Innate immune system mediators include the dysfunction of neutrophils, monocytes, and natural killer (NK) cells with signaling mediated by NOD-like receptor P3 (NLRP3) and Toll-like receptor 4 (TLR4); in addition, there is a significant activation of the complement system that is mediated by dialysis membrane-surfaces. These effectors induce a persistent, systemic, pro-inflammatory, and pro-coagulant milieu that has been described as inflammaging. The adaptive response, the imbalance in the CD4+/CD8+ T cell ratio, and the reduction of Th2 and regulatory T cells, together with an altered interaction with B lymphocyte by CD40/CD40L, have been mainly implicated in immune system dysfunction. Altogether, these observations suggest that intervention targeting the immune system in HD patients could improve morbidity and mortality. The purpose of this review is to expand our understanding on the role of immune dysfunction in both innate and adaptive response in patients undergoing hemodialysis treatment.

Daily and seasonal mitochondrial protection: Unraveling common possible mechanisms involving vitamin D and melatonin

From an evolutionary point of view, vitamin D and melatonin appeared very early and share functions related to defense mechanisms. In the current clinical setting, vitamin D is exclusively associated with phosphocalcic metabolism. Meanwhile, melatonin has chronobiological effects and influences the sleep-wake cycle. Scientific evidence, however, has identified new actions of both molecules in different physiological and pathological settings. The biosynthetic pathways of vitamin D and melatonin are inversely related relative to sun exposure. A deficiency of these molecules has been associated with the pathogenesis of cardiovascular diseases, including arterial hypertension, neurodegenerative diseases, sleep disorders, kidney diseases, cancer, psychiatric disorders, bone diseases, metabolic syndrome, and diabetes, among others. During aging, the intake and cutaneous synthesis of vitamin D, as well as the endogenous synthesis of melatonin are remarkably depleted, therefore, producing a state characterized by an increase of oxidative stress, inflammation, and mitochondrial dysfunction. Both molecules are involved in the homeostatic functioning of the mitochondria. Given the presence of specific receptors in the organelle, the antagonism of the renin-angiotensin-aldosterone system (RAAS), the decrease of reactive species of oxygen (ROS), in conjunction with modifications in autophagy and apoptosis, anti-inflammatory properties inter alia, mitochondria emerge as the final common target for melatonin and vitamin D. The primary purpose of this review is to elucidate the common molecular mechanisms by which vitamin D and melatonin might share a synergistic effect in the protection of proper mitochondrial functioning.

Bone, inflammation and chronic kidney disease

Increasing knowledge on inflammatory mediators and bone metabolism highlights the relationship between inflammation and bone disease. During acute illness, inflammatory cells and cytokines modulate bone cells activity so as to mobilize calcium seemingly to supply the metabolic requirements for immune response. In case of long lasting, chronic inflammatory states a condition of maladaptive, smouldering inflammation is realized and negatively affects calcium bone balance. Aging, now nicknamed inflammaging, is regarded as a chronic inflammatory condition, characterized by increased circulating inflammatory cytokines, that contributes to the development of osteoporosis, cardiovascular diseases and chronic kidney disease. In patients with renal insufficiency, the development of bone and mineral disorders (so called CKD-MBD "syndrome") is now a recognized pathogenic factor for the seemingly accelerated process of aging and for the increased risk of cardiovascular death in these patients. The adaptive changes in mineral and bone metabolism developing in the early stages of chronic kidney disease could represent a hypothetical model of accelerated aging, osteoporosis and cardiovascular disease.

Inflammation and Premature Ageing in Chronic Kidney Disease

Persistent low-grade inflammation and premature ageing are hallmarks of the uremic phenotype and contribute to impaired health status, reduced quality of life, and premature mortality in chronic kidney disease (CKD). Because there is a huge global burden of disease due to CKD, treatment strategies targeting inflammation and premature ageing in CKD are of particular interest. Several distinct features of the uremic phenotype may represent potential treatment options to attenuate the risk of progression and poor outcome in CKD. The nuclear factor erythroid 2-related factor 2 (NRF2)-kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1 (KEAP1) signaling pathway, the endocrine phosphate-fibroblast growth factor-23-klotho axis, increased cellular senescence, and impaired mitochondrial biogenesis are currently the most promising candidates, and different pharmaceutical compounds are already under evaluation. If studies in humans show beneficial effects, carefully phenotyped patients with CKD can benefit from them.

Examining the association between serum phosphate levels and leukocyte telomere length

Accelerated telomere attrition is related to various diseases, and multiple factors have been reported to influence telomere length. However, little attention has focused on the relationship between serum phosphate levels and mean telomere length. The purpose of this study was to explore the relationship between serum phosphate levels and mean telomere length in the US general population. A total of 7,817 participants from the 1999–2002 NHANES were included. The association between serum phosphate levels and mean telomere length was investigated using regression models. A remarkably positive relationship between serum phosphate levels and mean telomere length emerged after adjustments were made for covariates. The adjusted β coefficient of serum phosphate levels for mean telomere length was 0.038 (95% confidence intervals (CIs), 0.022 to 0.095, p = 0.002). A longer telomere length was observed in participants with serum phosphate levels in the highest quartiles, and a dose-dependent association was observed. Our study demonstrated that higher quartiles of phosphate had a remarkable correlation with longer telomere length.

Allicin pharmacology: Common molecular mechanisms against neuroinflammation and cardiovascular diseases

According to investigations in phytomedicine and ethnopharmacology, the therapeutic properties of garlic (Allium sativum) have been described by ancestral cultures. Notwithstanding, it is of particular concern to elucidate the molecular mechanisms underlying this millenary empirical knowledge. Allicin (S-allyl prop-2-ene-1-sulfinothioate), a thioester of sulfenic acid, is one of the main bioactive compounds present in garlic, and it is responsible for the particular aroma of the spice. The pharmacological attributes of allicin integrate a broad spectrum of properties (e.g., anti-inflammatory, immunomodulatory, antibiotic, antifungal, antiparasitic, antioxidant, nephroprotective, neuroprotective, cardioprotective, and anti-tumoral activities, among others). The primary goal of the present article is to review and clarify the common molecular mechanisms by which allicin and its derivates molecules may perform its therapeutic effects on cardiovascular diseases and neuroinflammatory processes. The intricate interface connecting the cardiovascular and nervous systems suggests that the impairment of one organ could contribute to the dysfunction of the other. Allicin might target the cornerstone of the pathological processes underlying cardiovascular and neuroinflammatory disorders, like inflammation, renin-angiotensin-aldosterone system (RAAS) hyperactivation, oxidative stress, and mitochondrial dysfunction. Indeed, the current evidence suggests that allicin improves mitochondrial function by enhancing the expression of HSP70 and NRF2, decreasing RAAS activation, and promoting mitochondrial fusion processes. Finally, allicin represents an attractive therapeutic alternative targeting the complex interaction between cardiovascular and neuroinflammatory disorders.

Nrf2 in early vascular ageing: Calcification, senescence and therapy

Under normal physiological conditions, free radical generation and antioxidant defences are balanced, and reactive oxygen species (ROS) usually act as secondary messengers in a plethora of biological processes. However, when this balance is impaired, oxidative stress develops due to imbalanced redox homeostasis resulting in cellular damage. Oxidative stress is now recognized as a trigger of cellular senescence, which is associated with multiple chronic 'burden of lifestyle' diseases, including atherosclerosis, type-2 diabetes, chronic kidney disease and vascular calcification; all of which possess signs of early vascular ageing. Nuclear factor erythroid 2-related factor 2 (Nrf2), termed the master regulator of antioxidant responses, is a transcription factor found to be frequently dysregulated in conditions characterized by oxidative stress and inflammation. Recent evidence suggests that activation of Nrf2 may be beneficial in protecting against vascular senescence and calcification. Both natural and synthetic Nrf2 agonists have been introduced as promising drug classes in different phases of clinical trials. However, overexpression of the Nrf2 pathway has also been linked to tumorigenesis, which highlights the requirement for further understanding of pathways involving Nrf2 activity, especially in the context of cellular senescence and vascular calcification. Therefore, comprehensive translational pre-clinical and clinical studies addressing the targeting capabilities of Nrf2 agonists are urgently required. The present review discusses the impact of Nrf2 in senescence and calcification in early vascular ageing, with focus on the potential clinical implications of Nrf2 agonists and non-pharmacological Nrf2 therapeutics.

Pomegranate juice improves cardiometabolic risk factors, biomarkers of oxidative stress and inflammation in hemodialysis patients: a randomized crossover trial

BACKGROUND

Pomegranate has antioxidant, cardioprotective and anti-inflammatory properties. We designed a crossover study aimed at determining if consumption of pomegranate juice (PJ) improves lipid profile and oxidative and inflammatory biomarkers of hemodialysis patients. Forty-one hemodialysis patients were randomly assigned to one of two groups: PJ-treated group receiving 100 mL of natural PJ immediately after their dialysis session three times a week and the control group receiving the usual care. After 8 weeks, a 4-week washout period was established and then the role of the groups was exchanged. Lipid profile, blood pressure and oxidative and inflammatory biomarkers were measured before and after each sequence.

RESULTS

Based on the results of intention-to-treat analysis, triglycerides were decreased in PJ condition and increased in the controls. Conversely, high-density lipoprotein cholesterol was increased in PJ and decreased in the control group. Total and low-density lipoprotein cholesterol did not significantly change in either condition. Systolic and diastolic blood pressure significantly decreased in PJ condition. Total antioxidant capacity increased in PJ condition (P < 0.001) and decreased in the controls (P < 0.001). Conversely, malondialdehyde and interleukin-6 decreased in PJ (P < 0.001) and increased in the control group (P ≤ 0.001). The changes of these biomarkers were significantly different between the two conditions.

CONCLUSIONS

Eight-week PJ consumption showed beneficial effects on blood pressure, serum triglycerides, high-density lipoprotein cholesterol, oxidative stress and inflammation in hemodialysis patients. © 2019 Society of Chemical Industry.

Sodium and water handling during hemodialysis: new pathophysiologic insights and management approaches for improving outcomes in end-stage kidney disease

Space medicine and new technology such as magnetic resonance imaging of tissue sodium stores (²³NaMRI) have changed our understanding of human sodium homeostasis and pathophysiology. It has become evident that body sodium comprises 3 main components. Two compartments have been traditionally recognized, namely one that is circulating and systemically active via its osmotic action, and one slowly exchangeable pool located in the bones. The third, recently described pool represents sodium stored in skin and muscle interstitium, and it is implicated in cell and biologic activities via local hypertonicity and sodium clearance mechanisms. This in-depth review provides a comprehensive view on the pathophysiology and existing knowledge gaps of systemic hemodynamic and tissue sodium accumulation in dialysis patients. Furthermore, we discuss how the combination of novel technologies to quantitate tissue salt accumulation (e.g., ²³NaMRI) with devices to facilitate the precise attainment of a prescribed hemodialytic sodium mass balance (e.g., sodium and water balancing modules) will improve our therapeutic approach to sodium management in dialysis patients. While prospective studies are required, we think that these new diagnostic and sodium balancing tools will enhance our ability to pursue more personalized therapeutic interventions on sodium and water management, with the eventual goal of improving dialysis patient outcomes.

Serum myostatin levels are associated with abdominal aortic calcification in dialysis patients

Background

Serum myostatin levels are increased according to renal function decline and myostatin may be a main mediator of chronic kidney disease–related sarcopenia. A previous study reported that serum myostatin level was negatively associated with abdominal aortic calcification (AAC) in older males. The aim of this study was to assess the association between serum myostatin level and AAC among dialysis patients of both sexes. In addition, we analyzed the relationship between serum myostatin level, muscle mass, and bone mineral density (BMD).

Methods

In this cross-sectional study, we evaluated AAC in the lateral lumbar spine using plain radiography and BMD in 71 patients undergoing dialysis. We classified patients into two groups according to the median value of myostatin as follows: those with high myostatin levels (≥ 5.0 ng/mL) and those with low myostatin levels (< 5.0 ng/mL).

Results

The proportion of patients with an AAC score of five points or more was higher among those with low myostatin levels. Myostatin level was negatively associated with AAC scores on plain radiography and had a positive association with skeletal muscle mass and T-scores for BMD measured at the total hip and femur neck. Lower myostatin levels were independently associated with higher AAC scores following adjustment for age, sex, diabetes mellitus, dialysis vintage, dialysis modality, and osteoprotegerin level.

Conclusion

Lower serum myostatin levels were associated with higher AAC scores, lower muscle mass, and lower BMD in dialysis patients. Further, prospective studies and those with larger cohorts are necessary to validate these findings.

Frailty Screening in Chronic Kidney Disease: Current Perspectives

Frailty has been defined as a state of increased vulnerability as a consequence of deficit accumulation. Frailty screening has not yet been widely implemented into routine nephrology care. Patients with chronic kidney disease (CKD) are at high risk of being frail, and frailty has been associated with worse outcomes in this population. Standard management of CKD, including initiation of renal replacement therapies, may have decreased benefit or potentially cause harm in the presence of frailty, and a variety of interventions for modifying frailty in the CKD population have been proposed. The optimal means of screening for frailty in patients with kidney disease remains unclear. This review highlights the value of frailty screening in CKD by summarizing the outcomes associated with frailty and exploring proposed changes to the management of frail patients with CKD. Finally, we will propose a framework for how to implement frailty screening into standard nephrology care.

Dietary Protein and Physical Activity Interventions to Support Muscle Maintenance in End-Stage Renal Disease Patients on Hemodialysis

End-stage renal disease patients have insufficient renal clearance capacity left to adequately excrete metabolic waste products. Hemodialysis (HD) is often employed to partially replace renal clearance in these patients. However, skeletal muscle mass and strength start to decline at an accelerated rate after initiation of chronic HD therapy. An essential anabolic stimulus to allow muscle maintenance is dietary protein ingestion. Chronic HD patients generally fail to achieve recommended protein intake levels, in particular on dialysis days. Besides a low protein intake on dialysis days, the protein equivalent of a meal is extracted from the circulation during HD. Apart from protein ingestion, physical activity is essential to allow muscle maintenance. Unfortunately, most chronic HD patients have a sedentary lifestyle. Yet, physical activity and nutritional interventions to support muscle maintenance are generally not implemented in routine patient care. To support muscle maintenance in chronic HD patients, quantity and timing of protein intake should be optimized, in particular throughout dialysis days. Furthermore, implementing physical activity either during or between HD sessions may improve the muscle protein synthetic response to protein ingestion. A well-orchestrated combination of physical activity and nutritional interventions will be instrumental to preserve muscle mass in chronic HD patients.

Kidney Dysfunction and the Risk of Developing Aortic Stenosis

BACKGROUND

Chronic kidney disease (CKD) and aortic stenosis (AS) share many risk factors.

OBJECTIVES

This study sought to evaluate whether kidney dysfunction is associated with the development of AS in the community.

METHODS

The study included 1,121,875 Stockholm citizens without a prior diagnosis of AS from the SCREAM (Stockholm CREAtinine Measurements) project. Estimated glomerular filtration rate (eGFR) (ml/min/1.73 m²) was calculated from serum creatinine. AS incidence during follow-up was ascertained by clinical diagnostic codes. The association between eGFR and AS incidence was estimated with multivariable Cox proportional hazards models. Sensitivity analyses included analysis of possible reverse causation bias by excluding the first 6 months to 2 years after enrollment and excluding individuals with comorbid heart failure.

RESULTS

The median age was 50 years (interquartile range [IQR]: 36 to 64 years), and 54% of participants were women. Median eGFR was 96 ml/min/1.73 m² (IQR: 82 to 109 ml/min/1.73 m²), and 66,949 (6.0%) participants had CKD (eGFR <60 ml/min/1.73 m²). During a median follow-up of 5.1 years (IQR: 3.3 to 6.1 years), 5,858 (0.5%) individuals developed AS (incidence rate [IR] 1.13/1,000 person-years). Compared with eGFR >90 (IR 0.34/1,000 person-years), lower eGFR strata were associated with higher hazards of AS: eGFR 60 to 90 ml/min/1.73 m²; IR: 1.88; hazard ratio (HR): 1.14; 95% confidence interval (CI): 1.05 to 1.25; eGFR 45 to 59 ml/min/1.73 m²; IR: 4.61; HR: 1.17; 95% CI: 1.05 to 1.30; eGFR 30 to 44 ml/min/1.73 m²; IR: 6.62; HR: 1.22; 95% CI: 1.07 to 1.39; and eGFR 30 ml/min/1.73 m²; IR: 8.27; HR: 1.56; 95% CI: 1.29 to 1.87. Sensitivity analysis attenuated only slightly the magnitude of the association; individuals with eGFR ≤44 ml/min/1.73 m² remained at an approximate 20% risk of AS both when excluding events within the 2 years after baseline (HR: 1.22; 95% CI: 1.06 to 1.42) and when excluding participants with heart failure (HR: 1.20; 95% CI: 1.03 to 1.39).

CONCLUSIONS

CKD, even in moderate to severe stages, is associated with an increased risk of AS.

Antioxidant modifications induced by the new metformin derivative HL156A regulate metabolic reprogramming in SAMP1/kl (-/-) mice

Aging is characterized by a reduced ability to defend against stress, an inability to maintain homeostasis, and an increased risk of disease. In this study, a metabolomics approach was used to identify novel metabolic pathways that are perturbed in a mouse model of accelerated aging (SAMP1/kl-/-) and to gain new insights into the metabolic associations of the metformin derivative HL156A. Extensive inflammation and calcification were observed in the tissues of the SAMP1/kl-/- mice with premature aging. In mouse embryonic fibroblasts (MEFs) obtained from SAMP1/kl-/- mice, we observed that HL156A induced FOXO1 expression through inhibition of the IGF-1/AKT/mTOR signaling pathways. Treatment of HL156A decreased reactive oxygen species production and enhanced mitochondrial transmembrane potential in SAMP1/kl-/- MEFs. A metabolomic profile analysis showed that HL156A increased the GSH/GSSG ratio in the kidneys of SAMP1/kl-/- mice (8-12 weeks old). In addition, treating SAMP1/kl-/- mice with HL156A (30 mg/kg) for 4 weeks improved survival and decreased the significant elevation of oxidized GSH (GSSG) that was observed in SAMP1/kl-/- mice. In histological sections, HL156A administered SAMP1/kl-/- mice exhibited a decrease in excessive calcification. Based on these findings, we conclude that the new metformin derivative HL156A may inhibit oxidative damage by inducing glutathione metabolism and antioxidant pathways.

Telomere length regulators are activated in young men after pediatric kidney transplantation compared to healthy controls and survivors of childhood cancer-A cross-sectional study

Chronic diseases are known to cause premature aging and frailty. Data about telomere length and telomere length-regulating proteins after pediatric KTx are scarce. Leukocyte telomere length and gene expression level of eight telomere-binding proteins were analyzed in 20 KTx recipients, eight childhood NBL survivors, and nine healthy controls. The influence of key clinical parameters on telomere length and on regulators of telomere length was evaluated. The telomere length in the KTx recipients tended to be shorter (0.53 AU) than in the healthy controls (0.64 AU) but longer than in the NBL survivors (0.38 AU). There was no significant difference in telomere length between the NBL survivors and the KTx recipients (P = .110). The gene expression level of telomere length-preserving protein RPA1 was significantly higher in the KTx recipients than among the NBL survivors or healthy controls, while the expression of TRF2 and the tumor suppressor gene p16 was significantly higher in the KTX recipients when compared to the controls. TRF2 and TIN2 correlated significantly with hsCRP; additionally, TRF2 showed significant correlation with plasma creatinine and eGFR. KTx recipients have near to normal telomere length, but they have significantly higher gene expression levels of telomere regulatory proteins compared with healthy controls, suggesting activation of mechanisms preserving telomere length among KTx recipients. Our results suggest that declined graft function and consequent inflammatory response may have influence on telomerase activity.

Chronic inflammation in end-stage renal disease and dialysis

Under normal conditions, inflammation is a protective and physiological response to various harmful stimuli. However, in several chronic debilitating disorders, such as chronic kidney disease, inflammation becomes maladaptive, uncontrolled and persistent. Systemic persistent inflammation has, for almost 20 years, been recognized as a major contributor to the uraemic phenotype (such as cardiovascular disease, protein energy wasting, depression, osteoporosis and frailty), and a predictor of cardiovascular and total mortality. Since inflammation is mechanistically related to several ageing processes (inflammageing), it may be a major driver of a progeric phenotype in the uraemic milieu. Inflammation is likely the consequence of a multifactorial aetiology and interacts with a number of factors that emerge when uraemic toxins accumulate. Beside interventions aiming to decrease the production of inflammatory molecules in the uraemic milieu, novel strategies to increase the removal of large middle molecules, such as expanded haemodialysis, may be an opportunity to decrease the inflammatory allostatic load associated with retention of middle molecular weight uraemic toxins.

Chronic prolonged hyponatremia and risk of hip fracture in elderly patients with chronic kidney disease

BACKGROUND

Chronic prolonged hyponatremia (CPH) is a risk factor for hip fracture in the general population. Whether CPH increases hip fracture risk in chronic kidney disease (CKD) patients is unknown.

METHODS

Case-control study in patients over 60 years of age with stage 3 or greater CKD. Patients who had a hip fracture were referred to as cases (n = 1236) and controls had no hip fracture (n = 4515). Patients were classified as having CPH if serum sodium was <135 mEq/L on at least two occasions separated by a minimum of 90 days prior to the diagnosis of hip fracture (cases) or at any time during the study period (controls). Conditional logistic regression models were used to test the association between CPH and hip fracture. Analyses were conducted for patients with and without osteoporosis and falls and for patients with age >70 years versus ≤70 years.

RESULTS

CPH was present in 21% of cases and 10% of controls (p < 0.001; sodium level: 131-134 mEq/L). In univariate logistic regression analysis, CPH was associated with higher odds of hip fracture (odds ratio [OR] 2.44, (95% [CI] 2.07-2.89). In a multivariate model adjusted for comorbidities, medications and laboratory parameters CPH association with higher odds of Hip fracture was attenuated but remained significant (OR 1.36, 95% CI 1.04-1.78). The association between CPH and risk of hip fracture was consistent in patients with or without osteoporosis and falls and across the age strata.

CONCLUSION

Chronic prolonged hyponatremia is a risk factor for hip fracture in CKD patients older than 60 years of age.

Serum 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, is associated with mortality independent of inflammation in chronic kidney disease

BACKGROUND

Oxidative stress and low-grade systemic inflammation are common interrelated sequelae of chronic kidney disease (CKD) that associate with mortality. We investigated the association of serum 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, with mortality in CKD individuals and analyzed whether inflammation modifies the association.

METHODS

In 376 individuals with a wide range of estimated glomerular filtration rate (eGFR); >60 ml/min (n = 53), 15-60 ml/min (n = 60) and <15 ml/min (n = 263), cut-off values of serum 8-OHdG, high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), and tumor necrosis factor (TNF) as predictors of mortality were determined by ROC curves. We analyzed associations of 8-OHdG with inflammation markers and the overlapping effect of hsCRP, IL-6 and TNF on the association between 8-OHdG and all-cause mortality by multivariate generalized linear models.

RESULTS

In separate individual exposure analyses, higher 8-OHdG, hsCRP, and IL-6 (but not TNF) were each independently associated with increased risk of death in multivariate models adjusted for age, sex, diabetes mellitus, cardiovascular disease, protein-energy wasting, cohort calendar year, blood sample storage time and eGFR. For 8-OHdG, the multivariate relative risk ratio, RR_8-OHdG (95% confidence interval) 1.17 (1.08-1.26), remained essentially unchanged when adjusting also for inflammation in three separate models including: hsCRP, RR_8-OHdG = 1.15 (1.06-1.25); IL-6, RR_8-OHdG = 1.15 (1.07-1.25); and TNF, RR_8-OHdG = 1.16 (1.07-1.26).

CONCLUSIONS

Serum 8-OHdG, a biomarker of oxidative DNA damage, is associated with increased all-cause mortality risk in individuals with a wide range of eGFR and this association is independent of inflammation.

The gut–kidney–heart axis in chronic kidney disease

The recent explosion of scientific interest in the gut microbiota has dramatically advanced our understanding of the complex pathophysiological interactions between the gut and multiple organs in health and disease. Emerging evidence has revealed that the gut microbiota is significantly altered in patients with chronic kidney disease (CKD), along with impaired intestinal barrier function. These alterations allow translocation of various gut-derived products into the systemic circulation, contributing to the development and progression of CKD and cardiovascular disease (CVD), partly mediated by chronic inflammation. Among potentially toxic gut-derived products identifiable in the systemic circulation, bacterial endotoxin and gut metabolites (e.g., p-cresyl sulfate and trimethylamine-N-oxide) have been extensively studied for their immunostimulatory and atherogenic properties. Recent studies have also suggested similar biological properties of bacterial DNA fragments circulating in the blood of patients with CKD, even in the absence of overt infections. Despite the accumulating evidence of the gut microbiota in CKD and its therapeutic potential for CVD, the precise mechanisms for multidirectional interactions between the gut, kidney, and heart remain poorly understood. This review aims to provide recent evidence on the associations between the gut microbiota, CKD, and CVD, and summarize current understanding of the potential pathophysiological mechanisms underlying the “gut–kidney–heart” axis in CKD.

Malnutrition and inflammation are associated with severity of depressive and cognitive symptoms of old patients affected by chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is a disabling condition associated with different medical comorbidities including depression and cognitive impairment. We investigated the association between malnutrition, inflammation and depressive/cognitive symptoms in elderly subjects with advanced CKD.

METHODS

We evaluated cross-sectionally 132 elderly subjects (age ≥65 years) with advanced CKD (stage 4-5, non-dialytic-ND) in regular follow up at the outpatient clinic of nephrology. Blood and urinary samples were collected after an overnight fast. All patients were evaluated by Geriatric Depression Scale (GDS)-30 items for severity of depressive symptoms, Mini Mental State Examination (MMSE) and the Clock Drawing Test (CDT) for cognition. Nutritional status was assessed by Malnutrition Inflammation Score (MIS). Different linear regression models were performed to study the association between clinical variables, diet and inflammatory parameters with the above mentioned rating scale scores. A final linear regression model with only previous statistically significant variables was performed for GDS scores.

RESULTS

Our cohort consisted of 95 males and 37 females with a mean age of 78 ± 7. Female gender (B = 3.20, p < .01), higher MIS (B = 0.29, p = .02) and higher IL-12p70 serum levels (pg/mL) (B = 0.37, p = .03) were associated with severity of depressive symptoms. MIS was associated with the severity of cognitive impairment as assessed by MMSE (B = -0.19, p < .01) and CDT (B = 0.10, p = .03).

CONCLUSION

In elderly subjects affected by CKD the severity of depressive symptoms and cognitive impairment is associated with specific inflammatory and nutritional parameters. These results have to be considered as preliminary and need replication by further studies.

Reduced skeletal muscle expression of mitochondrial-derived peptides humanin and MOTS-C and Nrf2 in chronic kidney disease

Advanced chronic kidney disease (CKD) is characterized by a premature aging phenotype of multifactorial origin. Mitochondrial dysfunction is prevalent in CKD and has been proposed as a major contributor to poor muscle function. Although the mitochondria-derived peptides (MDPs) humanin and mitochondrial open reading frame of 12S rRNA-c (MOTS-c) are involved in cell survival, suppression of apoptosis, and glucose control, the implications of MDP in CKD are unknown. We investigated humanin and MOTS-c protein expression in skeletal muscle and serum levels in CKD at stage 5 (glomerular filtration rate: <15 ml/min) patients and age-matched controls with normal renal function. Whereas circulating levels of humanin were increased in CKD, local muscle expression was reduced. In contrast, MOTS-c levels were reduced in both skeletal muscle and serum in CKD. Humanin in serum correlated positively to circulating TNF levels. Reduced MDP levels in skeletal muscle were associated with lower mitochondrial density and evidence of oxidative stress. These results indicate a differential regulation of MDPs in CKD and suggest an alternative site for humanin production than skeletal muscle in the uremic milieu. MDP levels were linked to systemic inflammation and evidence of oxidative stress in the muscle, two hallmark features of premature aging and uremia.

Organ crosstalk: the potent roles of inflammation and fibrotic changes in the course of organ interactions

BACKGROUND

Organ crosstalk can be defined as the complex and mutual biological communication between distant organs mediated by signaling factors. Normally, crosstalk helps to coordinate and maintain homeostasis, but sudden or chronic dysfunction in any organ causes dysregulation in another organ. Many signal molecules, including cytokines and growth factors, are involved in the metabolic dysregulation, and excessive or inappropriate release of these molecules leads to organ dysfunction or disease (e.g., obesity, type 2 diabetes).

AIM AND METHOD

The aim of this review is to reveal the impact of organ crosstalk on the pathogenesis of diseases associated with organ interactions and the role of inflammatory and fibrotic changes in the organ dysfunction. After searching in MEDLINE, PubMed and Google Scholar databases using 'organ crosstalk' as a keyword, studies related to organ crosstalk and organ interaction were compiled and examined.

CONCLUSION

The organ crosstalk and the functional integration of organ systems are exceedingly complex processes. Organ crosstalk contributes to metabolic homeostasis and affects the inflammatory response, related pathways and fibrotic changes. As in the case of interactions between adipose tissue and intestine, stimulation of inflammatory mechanisms plays an active role in the development of diseases including insulin resistance, obesity, type 2 diabetes and hepatic steatosis. The increased level of knowledge about the 'crosstalk' between any organ and distant organs will facilitate the early diagnosis of the disease as well as the management of the treatment practices in the short- and long-term organ dysfunction.

Evolution, kidney development, and chronic kidney disease

There is a global epidemic of chronic kidney disease (CKD) characterized by a progressive loss of nephrons, ascribed in large part to a rising incidence of hypertension, metabolic syndrome, and type 2 diabetes mellitus. There is a ten-fold variation in nephron number at birth in the general population, and a 50% overall decrease in nephron number in the last decades of life. The vicious cycle of nephron loss stimulating hypertrophy by remaining nephrons and resulting in glomerulosclerosis has been regarded as maladaptive, and only partially responsive to angiotensin inhibition. Advances over the past century in kidney physiology, genetics, and development have elucidated many aspects of nephron formation, structure and function. Parallel advances have been achieved in evolutionary biology, with the emergence of evolutionary medicine, a discipline that promises to provide new insight into the treatment of chronic disease. This review provides a framework for understanding the origins of contemporary developmental nephrology, and recent progress in evolutionary biology. The establishment of evolutionary developmental biology (evo-devo), ecological developmental biology (eco-devo), and developmental origins of health and disease (DOHaD) followed the discovery of the hox gene family, the recognition of the contribution of cumulative environmental stressors to the changing phenotype over the life cycle, and mechanisms of epigenetic regulation. The maturation of evolutionary medicine has contributed to new investigative approaches to cardiovascular disease, cancer, and infectious disease, and promises the same for CKD. By incorporating these principles, developmental nephrology is ideally positioned to answer important questions regarding the fate of nephrons from embryo through senescence.

The interplay between mineral metabolism, vascular calcification and inflammation in Chronic Kidney Disease (CKD): challenging old concepts with new facts

Chronic kidney disease (CKD) is one of the most powerful predictors of premature cardiovascular disease (CVD), with heightened susceptibility to vascular intimal and medial calcification associated with a high cardiovascular mortality. Abnormal mineral metabolism of calcium (Ca) and phosphate (P) and underlying (dys)regulated hormonal control in CKD-mineral and bone disorder (MBD) is often accompanied by bone loss and increased vascular calcification (VC). While VC is known to be a multifactorial process and a major risk factor for CVD, the view of primary triggers and molecular mechanisms complexity has been shifting with novel scientific knowledge over the last years. In this review we highlight the importance of calcium-phosphate (CaP) mineral crystals in VC with an integrated view over the complexity of CKD, while discuss past and recent literature aiming to highlight novel horizons on this major health burden. Exacerbated VC in CKD patients might result from several interconnected mechanisms involving abnormal mineral metabolism, dysregulation of endogenous calcification inhibitors and inflammatory pathways, which function in a feedback loop driving disease progression and cardiovascular outcomes. We propose that novel approaches targeting simultaneously VC and inflammation might represent valuable new prognostic tools and targets for therapeutics and management of cardiovascular risk in the CKD population.

Early Vascular Ageing and Cellular Senescence in Chronic Kidney Disease

Chronic kidney disease (CKD) is a clinical model of premature ageing characterized by progressive vascular disease, systemic inflammation, muscle wasting and frailty. The predominant early vascular ageing (EVA) process mediated by medial vascular calcification (VC) results in a marked discrepancy between chronological and biological vascular age in CKD. Though the exact underlying mechanisms of VC and EVA are not fully elucidated, accumulating evidence indicates that cellular senescence - and subsequent chronic inflammation through the senescence-associated secretary phenotype (SASP) - plays a fundamental role in its initiation and progression. In this review, we discuss the pathophysiological links between senescence and the EVA process in CKD, with focus on cellular senescence and media VC, and potential anti-ageing therapeutic strategies of senolytic drugs targeting cellular senescence and EVA in CKD.

Racial differences in inflammation and outcomes of aging among kidney transplant candidates

Background

Inflammation is more common among African Americans (AAs), and it is associated with frailty, poor physical performance, and mortality in community-dwelling older adults. Given the elevated inflammation levels among end-stage renal disease (ESRD) patients, inflammation may be associated with adverse health outcomes such as frailty, physical impairment, and poor health-related quality of life (HRQOL), and these associations may differ between AA and non-AA ESRD patients.

Methods

One thousand three ESRD participants were recruited at kidney transplant evaluation (4/2014–5/2017), and inflammatory markers (interleukin-6 [IL-6], tumor necrosis factor-a receptor-1 [TNFR1], C-reactive protein [CRP]) were measured. We quantified the association with frailty (Fried phenotype), physical impairment (Short Physical Performance Battery [SPPB]), and fair/poor HRQOL at evaluation using adjusted modified Poisson regression and tested whether these associations differed by race (AA vs. non-AA).

Results

Non-AAs had lower levels of TNFR1 (9.7 ng/ml vs 14.0 ng/ml, p < 0.001) and inflammatory index (6.7 vs 6.8, p < 0.001) compared to AAs, but similar levels of IL-6 (4.5 pg/ml vs 4.3 pg/ml, p > 0.9) and CRP (4.7 μg/ml vs 4.9 μg/ml, p = 0.4). Non-AAs had an increased risk of frailty with elevated IL-6 (RR = 1.58, 95% CI:1.27–1.96, p < 0.001), TNFR1 (RR = 1.60, 95% CI:1.25–2.05, p < 0.001), CRP (RR = 1.41, 95% CI:1.10–1.82, p < 0.01), and inflammatory index (RR = 1.82, 95% CI:1.44–2.31, p < 0.001). The associations between elevated inflammatory markers and frailty were not present among AAs. Similar results were seen with SPPB impairment and poor/fair HRQOL.

Conclusions

Non-AAs with elevated inflammatory markers may need closer follow-up and may benefit from prehabilitation to improve physical function, reduce frailty burden, and improve quality of life prior to transplant.

The peculiar aging of human liver: A geroscience perspective within transplant context

An appraisal of recent data highlighting aspects inspired by the new Geroscience perspective are here discussed. The main findings are summarized as follows: i) liver has to be considered an immunological organ, and new studies suggest a role for the recently described cells named telocytes; ii) the liver-gut axis represents a crucial connection with environment and life style habits and may influence liver diseases onset; iii) the physiological aging of liver shows relatively modest alterations. Nevertheless, several molecular changes appear to be relevant: a) an increase of microRNA-31-5p; -141-3p; -200c-3p expressions after 60 years of age; b) a remodeling of genome-wide DNA methylation profile evident until 60 years of age and then plateauing; c) changes in transcriptome including the metabolic zones of hepatocyte lobules; d) liver undergoes an accelerated aging in presence of chronic inflammation/liver diseases in a sort of continuum, largely as a consequence of unhealthy life styles and exposure to environmental noxious agents. We argue that chronic liver inflammation has all the major characteristics of "inflammaging" and likely sustains the onset and progression of liver diseases. Finally, we propose to use a combination of parameters, mostly obtained by omics such as transcriptomics and epigenomics, to evaluate in deep both the biological age of liver (in comparison with the chronological age) and the effects of donor-recipient age-mismatches in the context of liver transplant.

Genetics, Genomics, and Precision Medicine in End-Stage Kidney Disease

Recent advances in genetics of renal disease have deepened our understanding of progressive kidney disease. Here, we review genetic variants that are of particular importance to progressive glomerular disease that result in end-stage kidney disease (ESKD). Some of the most striking findings relate to APOL1 genetic variants, seen exclusively in individuals of sub-Saharan African descent, that create a predisposition to particular renal disorders, including focal segmental glomerulosclerosis and arterionephrosclerosis. We also review the genetics of cardiovascular disease in ESKD and note that little work has been published on the genetics of other ESKD complications, including anemia, bone disease, and infections. Deeper understanding of the genetics of ESKD and its complications may lead to new therapies that are tailored to an individual patient's genetic profile or are discovered based on genetic approaches that identify novel pathways of renal cell injury and repair.

Higher albumin:creatinine ratio and lower estimated glomerular filtration rate are potential risk factors for decline of physical performance in the elderly: the Cardiovascular Health Study

Introduction

Mildly reduced renal function and elevated urine protein levels are each prospectively associated with hip fracture risk in older adults. Here we determine whether these markers are associated with reduced appendicular muscle performance.

Methods

We prospectively examined the associations of urine albumin:creatinine ratio (ACR) and reduced estimated glomerular filtration rate (eGFR) with longitudinal changes in grip strength and gait speed >2 years in 2317 older community-dwelling men and women (median age 77 years). The median ACR was 9.8 [interquartile range (IQR) 5.40–21.50] mg/g creatinine and the median eGFR was 71.6 (IQR 59.1–83.56) mL/min/1.73 m². Models were adjusted for demographic factors, clinical history and biochemical measures in four candidate pathways: diabetes, oxidative stress, inflammation and fibrosis.

Results

In demographic- and covariate-adjusted models, a 2-fold higher baseline urine ACR was associated with longitudinal changes of −0.17 kg [95% confidence interval (CI) −0.29 to −0.06) in grip strength and −1.10 cm/s (95% CI −1.67 to −0.53) gait speed per year. Corresponding estimates for a 10 mL/min/1.73 m² lower baseline eGFR were −0.13 kg (95% CI −0.23 to −0.04) and −0.89 cm/s (95% CI −1.37 to −0.40), respectively. The associations of a 2-fold higher baseline ACR and a 10 mL/min/1.73 m² lower baseline eGFR using cystatin C with grip strength and gait speed were equivalent to ∼1.2–1.9 additional years of age. Adjustment for covariates in candidate pathways did not attenuate these estimates.

Conclusions

In older adults, higher ACR and lower eGFR are potential risk factors for a decline of physical performance >2 years.

Dermal tissue remodeling and non-osmotic sodium storage in kidney patients

Background

Excess dietary sodium is not only excreted by the kidneys, but can also be stored by non-osmotic binding with glycosaminoglycans in dermal connective tissue. Such storage has been associated with dermal inflammation and lymphangiogenesis. We aim to investigate if skin storage of sodium is increased in kidney patients and if this storage is associated with clinical parameters of sodium homeostasis and dermal tissue remodeling.

Methods

Abdominal skin tissue of 12 kidney patients (5 on hemodialysis) and 12 healthy kidney donors was obtained during surgery. Skin biopsies were processed for dermal sodium measurement by atomic absorption spectroscopy, and evaluated for CD⁶⁸⁺ macrophages, CD³⁺ T-cells, collagen I, podoplanin + lymph vessels, and glycosaminoglycans by qRT-PCR and immunohistochemistry.

Results

Dermal sodium content of kidney patients did not differ from healthy individuals, but was inversely associated with plasma sodium values (p < 0.05). Compared to controls, kidney patients showed dermal tissue remodeling by increased CD⁶⁸⁺ macrophages, CD³⁺ T-cells and Collagen I expression (all p < 0.05). Also, both N- and O-sulfation of heparan sulfate glycosaminoglycans were increased (all p < 0.05), most outspoken in hemodialysis patients. Plasma and urinary sodium associates with dermal lymph vessel number (both p < 0.05), whereas loss of eGFR, proteinuria and high systolic blood pressure associated with dermal macrophage density (all p < 0.05).

Conclusion

Kidney patients did not show increased skin sodium storage compared to healthy individuals. Results do indicate that kidney failure associates with dermal inflammation, whereas increased sodium excretion and plasma sodium associate with dermal lymph vessel formation and loss of dermal sodium storage capacity.

Trial registration The cohort is registered at clinicaltrials.gov as NCT (September 6, 2017). NCT, NCT03272841. Registered 6 September 2017—Retrospectively registered, https://clinicaltrials.gov

Methyl Donor Nutrients in Chronic Kidney Disease: Impact on the Epigenetic Landscape

Epigenetic alterations, such as those linked to DNA methylation, may potentially provide molecular explanations for complications associated with altered gene expression in illnesses, such as chronic kidney disease (CKD). Although both DNA hypo- and hypermethylation have been observed in the uremic milieu, this remains only a single aspect of the epigenetic landscape and, thus, of any biochemical dysregulation associated with CKD. Nevertheless, the role of uremia-promoting alterations on the epigenetic landscape regulating gene expression is still a novel and scarcely studied field. Although few studies have actually reported alterations of DNA methylation via methyl donor nutrient intake, emerging evidence indicates that nutritional modification of the microbiome can affect one-carbon metabolism and the capacity to methylate the genome in CKD. In this review, we discuss the nutritional modifications that may affect one-carbon metabolism and the possible impact of methyl donor nutrients on the microbiome, CKD, and its phenotype.

Cell-free DNA as a biomarker of aging

Cell-free DNA (cfDNA) is present in the circulating plasma and other body fluids and is known to originate mainly from apoptotic cells. Here, we provide the first in vivo evidence of global and local chromatin changes in human aging by analyzing cfDNA from the blood of individuals of different age groups. Our results show that nucleosome signals inferred from cfDNA are consistent with the redistribution of heterochromatin observed in cellular senescence and aging in other model systems. In addition, we detected a relative cfDNA loss at several genomic locations, such as transcription start and termination sites, 5'UTR of L1HS retrotransposons and dimeric AluY elements with age. Our results also revealed age and deteriorating health status correlate with increased enrichment of signals from cells in different tissues. In conclusion, our results show that the sequencing of circulating cfDNA from human blood plasma can be used as a noninvasive methodology to study age-associated changes to the epigenome in vivo.

Genome assembly and gene expression in the American black bear provides new insights into the renal response to hibernation

The prevalence of chronic kidney disease (CKD) is rising worldwide and 10-15% of the global population currently suffers from CKD and its complications. Given the increasing prevalence of CKD there is an urgent need to find novel treatment options. The American black bear (Ursus americanus) copes with months of lowered kidney function and metabolism during hibernation without the devastating effects on metabolism and other consequences observed in humans. In a biomimetic approach to better understand kidney adaptations and physiology in hibernating black bears, we established a high-quality genome assembly. Subsequent RNA-Seq analysis of kidneys comparing gene expression profiles in black bears entering (late fall) and emerging (early spring) from hibernation identified 169 protein-coding genes that were differentially expressed. Of these, 101 genes were downregulated and 68 genes were upregulated after hibernation. Fold changes ranged from 1.8-fold downregulation (RTN4RL2) to 2.4-fold upregulation (CISH). Most notable was the upregulation of cytokine suppression genes (SOCS2, CISH, and SERPINC1) and the lack of increased expression of cytokines and genes involved in inflammation. The identification of these differences in gene expression in the black bear kidney may provide new insights in the prevention and treatment of CKD.

Surgical outcomes of renal transplant recipients after abdominal surgery not connected with transplantation. A retrospective case-control study

BACKGROUND

Due to the increasing number of patients after kidney transplantation, elective and emergency surgery of transplanted patients is becoming a relevant challenge in clinical routine. The current data on complication rate of patients after kidney transplantation, which must undergo another elective or emergency abdominal surgery, is inhomogeneous. Therefore, the aim of our study was to evaluate the outcome of renal transplant patients undergoing abdominal and abdominal wall surgery.

MATERIAL AND METHODS

We performed an observational study of patients after kidney transplantation undergoing graft-unrelated abdominal surgery between 2005 and 2015. We randomly created a non-transplanted control for a case-matched controlled analysis. Primary endpoint was the comparison of complication rate. Secondary, a risk analysis of all patients was performed and differences in mortality, length of hospital stay and reoperation rates were calculated.

RESULTS

Overall 101 kidney transplanted patients were eligible for inclusion. 20 (19.8%) died after graft-unrelated surgery and 60 (59.4%) suffered from postoperative complications. Case-matched analysis could be performed for 84 out of these 101 patients. We found no significant difference in morbidity rate (58.3% vs. 45.2%, p = 0.090). Transplanted patients had, however, a significantly higher mortality (19% vs. 2.4%, p = 0.001), a longer hospital stay (28.2 vs. 16.9 days, p = 0.020) and a higher rate of re-operations (38.1% vs. 20.2%, p = 0.017). .

CONCLUSIONS

Patients after renal transplantation undergoing graft-unrelated abdominal surgery have a significantly increased mortality risk, are more frequently re-operated and have to stay significantly longer in hospital than non-transplanted patients.

Circulating proteins as predictors of cardiovascular mortality in end-stage renal disease

Introduction

Proteomic profiling of end-stage renal disease (ESRD) patients could lead to improved risk prediction and novel insights into cardiovascular disease mechanisms. Plasma levels of 92 cardiovascular disease-associated proteins were assessed by proximity extension assay (Proseek Multiplex CVD-1, Olink Bioscience, Uppsala, Sweden) in a discovery cohort of dialysis patients, the Mapping of Inflammatory Markers in Chronic Kidney disease cohort [MIMICK; n = 183, 55% women, mean age 63 years, 46 cardiovascular deaths during follow-up (mean 43 months)]. Significant results were replicated in the incident and prevalent hemodialysis arm of the Salford Kidney Study [SKS dialysis study, n = 186, 73% women, mean age 62 years, 45 cardiovascular deaths during follow-up (mean 12 months)], and in the CKD5-LD-RTxcohort with assessments of coronary artery calcium (CAC)-score by cardiac computed tomography (n = 89, 37% women, mean age 46 years).

Results

In age and sex-adjusted Cox regression in MIMICK, 11 plasma proteins were nominally associated with cardiovascular mortality (in order of significance: Kidney injury molecule-1 (KIM-1), Matrix metalloproteinase-7, Tumour necrosis factor receptor 2, Interleukin-6, Matrix metalloproteinase-1, Brain-natriuretic peptide, ST2 protein, Hepatocyte growth factor, TNF-related apoptosis inducing ligand receptor-2, Spondin-1, and Fibroblast growth factor 25). Only plasma KIM-1 was associated with cardiovascular mortality after correction for multiple testing, but also after adjustment for dialysis vintage, cardiovascular risk factors and inflammation (hazard ratio) per standard deviation (SD) increase 1.84, 95% CI 1.26–2.69, p = 0.002. Addition of KIM-1, or nine of the most informative proteins to an established risk-score (modified AROii CVM-score) improved discrimination of cardiovascular mortality risk from C = 0.777 to C = 0.799 and C = 0.823, respectively. In the SKS dialysis study, KIM-1 predicted cardiovascular mortality in age and sex adjusted models (hazard ratio per SD increase 1.45, 95% CI 1.03–2.05, p = 0.034) and higher KIM-1 was associated with higher CACscores in the CKD5-LD-RTx-cohort.

Conclusions

Our proteomics approach identified plasma KIM-1 as a risk marker for cardiovascular mortality and coronary artery calcification in three independent ESRD-cohorts. The improved risk prediction for cardiovascular mortality by plasma proteomics merit further studies.

Electronic supplementary material

The online version of this article (10.1007/s40620-018-0556-5) contains supplementary material, which is available to authorized users.

Cycles, Arrows and Turbulence: Time Patterns in Renal Disease, a Path from Epidemiology to Personalized Medicine?

Patients with end-stage renal disease (ESRD) experience unique patterns in their lifetime, such as the start of dialysis and renal transplantation. In addition, there is also an intricate link between ESRD and biological time patterns. In terms of cyclic patterns, the circadian blood pressure (BP) rhythm can be flattened, contributing to allostatic load, whereas the circadian temperature rhythm is related to the decline in BP during hemodialysis (HD). Seasonal variations in BP and interdialytic-weight gain have been observed in ESRD patients in addition to a profound relative increase in mortality during the winter period. Moreover, nonphysiological treatment patters are imposed in HD patients, leading to an excess mortality at the end of the long interdialytic interval. Recently, new evidence has emerged on the prognostic impact of trajectories of common clinical and laboratory parameters such as BP, body temperature, and serum albumin, in addition to single point in time measurements. Backward analysis of changes in cardiovascular, nutritional, and inflammatory parameters before the occurrence as hospitalization or death has shown that changes may already occur within months to even 1-2 years before the event, possibly providing a window of opportunity for earlier interventions. Disturbances in physiological variability, such as in heart rate, characterized by a loss of fractal patterns, are associated with increased mortality. In addition, an increase in random variability in different parameters such as BP and sodium is also associated with adverse outcomes. Novel techniques, based on time-dependent analysis of variability and trends and interactions of multiple physiological and laboratory parameters, for which machine-learning -approaches may be necessary, are likely of help to the clinician in the future. However, upcoming research should also evaluate whether dynamic patterns observed in large epidemiological studies have relevance for the individual risk profile of the patient.

Endogenous Anti-Inflammatory Very-Long-Chain Dicarboxylic Acids: Potential Chemopreventive Lipids

In a paradigm shift, cancer research efforts are being dedicated to the discovery of chemopreventive agents. The goal of this approach is to delay or prevent the progression of augmented cell division to established cancer. Research has focused on dietary supplements, drugs, and endogenous lipids that possess anti-inflammatory properties. We undertook a lipidomics analysis of potential endogenous anti-inflammatory/anti-proliferative lipids in human plasma. We performed high-resolution mass spectrometric lipidomics analyses of plasma samples from controls and patients with colorectal, kidney, pancreatic, glioblastoma, and breast cancers. We present evidence that endogenous very-long-chain dicarboxylic acids (VLCDCA) are anti-inflammatory lipids that possess chemopreventative properties. In a family of VLCDCAs, we characterized VLCDCA 28:4, which is decreased in the plasma of patients with colorectal, kidney, and pancreatic cancers. The structure of this biomarker was validated by derivatization strategies, synthesis of the analytical standard, and tandem mass spectrometry. Our data suggest that VLCDCA 28:4 may be a useful blood biomarker for a number of cancers and that resupplying this lipid, via a prodrug for example, may offer a new anti-inflammatory therapeutic strategy for delaying or preventing the progression of cancer and other inflammatory diseases.

Energy restriction in renal protection

Energy restriction (ER) has been widely studied as a novel intervention, and its ability to prolong life has been fully demonstrated. For example, ER can significantly extend the lifespans of model flies, worms, rodents and other mammals. The role of ER in renal protection has also been elucidated. In preclinical studies, adjusting total energy intake or consumption of specific nutrients has prophylactic or therapeutic effects on ageing-related kidney disease and acute and chronic kidney injury. Amino acid restriction has gradually attracted attention. ER mimetics have also been studied in depth. The protective mechanisms of ER and ER mimetics for renal injury include increasing AMP-activated protein kinase and sirtuin type 1 (Sirt1) levels and autophagy and reducing mammalian target of rapamycin, inflammation and oxidative stress. However, the renal protective effect of ER has mostly been investigated in rodent models, and the role of ER in patients cannot be determined due to the lack of large randomised controlled trials. To protect the kidney, the mechanism of ER must be thoroughly researched, and more accurate diet or drug interventions need to be identified.

Inflammation-Related Mechanisms in Chronic Kidney Disease Prediction, Progression, and Outcome

Persistent, low-grade inflammation is now considered a hallmark feature of chronic kidney disease (CKD), being involved in the development of all-cause mortality of these patients. Although substantial improvements have been made in clinical care, CKD remains a major public health burden, affecting 10–15% of the population, and its prevalence is constantly growing. Due to its insidious nature, CKD is rarely diagnosed in early stages, and once developed, its progression is unfortunately irreversible. There are many factors that contribute to the setting of the inflammatory status in CKD, including increased production of proinflammatory cytokines, oxidative stress and acidosis, chronic and recurrent infections, altered metabolism of adipose tissue, and last but not least, gut microbiota dysbiosis, an underestimated source of microinflammation. In this scenario, a huge step forward was made by the increasing progression of omics approaches, specially designed for identification of biomarkers useful for early diagnostic and follow-up. Recent omics advances could provide novel insights in deciphering the disease pathophysiology; thus, identification of circulating biomarker panels using state-of-the-art proteomic technologies could improve CKD early diagnosis, monitoring, and prognostics. This review aims to summarize the recent knowledge regarding the relationship between inflammation and CKD, highlighting the current proteomic approaches, as well as the inflammasomes and gut microbiota dysbiosis involvement in the setting of CKD, culminating with the troubling bidirectional connection between CKD and renal malignancy, raised on the background of an inflammatory condition.

Systemic Activation of Activin A Signaling Causes Chronic Kidney Disease-Mineral Bone Disorder

The high cardiovascular mortality associated with chronic kidney disease (CKD) is caused in part by the CKD-mineral bone disorder (CKD-MBD) syndrome. The CKD-MBD consists of skeletal, vascular and cardiac pathology caused by metabolic derangements produced by kidney disease. The prevalence of osteopenia/osteoporosis resulting from the skeletal component of the CKD-MBD, renal osteodystrophy (ROD), in patients with CKD exceeds that of the general population and is a major public health concern. That CKD is associated with compromised bone health is widely accepted, yet the mechanisms underlying impaired bone metabolism in CKD are not fully understood. Therefore, clarification of the molecular mechanisms by which CKD produces ROD is of crucial significance. We have shown that activin A, a member of the transforming growth factor (TGF)-β super family, is an important positive regulator of receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis with Smad-mediated signaling being crucial for inducing osteoclast development and function. Recently, we have demonstrated systemic activation of activin receptors and activin A levels in CKD mouse models, such as diabetic CKD and Alport (AL) syndrome. In these CKD mouse models, bone remodeling caused by increased osteoclast numbers and activated osteoclastic bone resorption was observed and treatment with an activin receptor ligand trap repaired CKD-induced-osteoclastic bone resorption and stimulated individual osteoblastic bone formation, irrespective of parathyroid hormone (PTH) elevation. These findings have opened a new field for exploring mechanisms of activin A-enhanced osteoclast formation and function in CKD. Activin A appears to be a strong candidate for CKD-induced high-turnover ROD. Therefore, the treatment with the decoy receptor for activin A might be a good candidate for treatment for CKD-induced osteopenia or osteoporosis, indicating that the new findings from in these studies will lead to the identification of novel therapeutic targets for CKD-related and osteopenia and osteoporosis in general. In this review, we describe the impact of CKD-induced Smad signaling in osteoclasts, osteoblasts and vascular cells in CKD.

Vascular Calcification in Chronic Kidney Disease: The Role of Inflammation

Cardiovascular complications are extremely frequent in patients with chronic kidney disease (CKD) and death from cardiac causes is the most common cause of death in this particular population. Cardiovascular disease is approximately 3 times more frequent in patients with CKD than in other known cardiovascular risk groups and cardiovascular mortality is approximately 10-fold more frequent in patients on dialysis compared to the age- and sex-matched segments of the nonrenal population. Among other structural and functional factors advanced calcification of atherosclerotic plaques as well as of the arterial and venous media has been described as potentially relevant for this high cardiovascular morbidity and mortality. One potential explanation for this exceedingly high vascular calcification in animal models as well as in patients with CKD increased systemic and most importantly local (micro)inflammation that has been shown to favor the development of calcifying particles by multiple ways. Of note, local vascular upregulation of proinflammatory and proosteogenic molecules is already present at early stages of CKD and may thus be operative for vascular calcification. In addition, increased expression of costimulatory molecules and mast cells has also been documented in patients with CKD pointing to a more inflammatory and potentially less stable phenotype of coronary atherosclerotic plaques in CKD.

Aerobic exercise-stimulated Klotho upregulation extends life span by attenuating the excess production of reactive oxygen species in the brain and kidney

Aerobic exercise induces many adaptive changes in the whole body and improves metabolic characteristics. Klotho, an anti-aging gene, is mainly expressed in the brain and kidney. The roles of Klotho in the brain and kidney during aerobic exercise remain largely unknown. The present study aimed to determine whether aerobic exercise could influence the expression of Klotho, decrease reactive oxygen species (ROS) and prolong life span. Sprague Dawley rats were exercised on a motor treadmill. Klotho mRNA and protein expression levels in rat brain and kidney tissues were examined using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. ROS production was detected following intermittent aerobic exercise (IAE) or continuous aerobic exercise (CAE). Kaplan-Meier curve analysis demonstrated that aerobic exercise significantly improved rat survival (P<0.001). The ROS levels in rat brain and kidney tissues were decreased in the aerobic exercise groups compared with the control group (P<0.05). In addition, Klotho mRNA and protein expression levels were increased significantly following aerobic exercise compared with controls (P<0.05). There was no significant difference between the IAE and CAE groups in any experiments (P>0.05). These results suggest that aerobic exercise-stimulated Klotho upregulation extends the life span by attenuating the excess production of ROS in the brain and kidney. As Klotho exhibits a potential anti-aging effect, promoting Klotho expression through aerobic exercise may be a novel approach for the prevention and treatment of aging and aging-related diseases.

Impact of Altered Intestinal Microbiota on Chronic Kidney Disease Progression

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of CKD progression. Some uremic toxins result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves, such as trimethylamine N-Oxide (TMAO), p-cresyl sulphate, indoxyl sulphate and indole-3 acetic acid. Increased intake of some nutrients may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of CKD progression. This offers the opportunity for therapeutic intervention by either modifying the diet, modifying the microbiota, decreasing uremic toxin production by microbiota, increasing toxin excretion or targeting specific uremic toxins. We now review the link between nutrients, microbiota and uremic toxin with CKD progression. Specific focus will be placed on the generation specific uremic toxins with nephrotoxic potential, the decreased availability of bacteria-derived metabolites with nephroprotective potential, such as vitamin K and butyrate and the cellular and molecular mechanisms linking these toxins and protective factors to kidney diseases. This information provides a conceptual framework that allows the development of novel therapeutic approaches.

Soluble Toll-like Receptor 4: A New Player in Subclinical Inflammation and Malnutrition in Hemodialysis Patients

OBJECTIVE

Toll-like receptor 4 (TLR4) promotes inflammation in hemodialysis patients (HD). A soluble form of extracellular TLR4 (sTLR4) has been recently characterized, which showed the ability to attenuate TLR4 signalling. In this study, we describe the sTLR4 profile in regular HD patients.

SUBJECTS

In a cross-sectional study we enrolled forty prevalent HD patients (68.2 ± 16.3 years, twenty-five males) with a median dialysis vintage of 41 months. Nineteen patients were undergoing standard bicarbonate HD (BHD) and 21 patients on-line hemodiafiltration (HDF). Ten healthy sex-matched subjects constituted the controls (C).

INTERVENTION

Before and after the HD session, serum was tested for sTLR4 levels by ELISA. Moreover, clinical and biochemical data were collected, including body mass index, albumin, and C-reactive protein (CRP) levels. Body composition was expressed as a 3-compartment model, providing lean tissue index and fat tissue index (FTI).

MAIN OUTCOME MEASURE

Describe the profile of sTLR4 in HD patients, evaluating the correlations among sTLR4 levels and the main clinical characteristics, inflammatory and nutritional parameters.

RESULTS

Patients with subclinical inflammation (i.e., high CRP levels without clinical symptomatology) presented higher sTLR4 levels (0.42 ± 0.25 ng/mL) with respect to both C and not inflamed HD patients (0.23 ± 0.19 ng/mL, P < .05). There was a significant direct correlation between predialysis sTLR4 and body mass index, FTI (r = 0.55), and CRP levels (r = 0.52) and inverse correlation with lean tissue index and albumin (r = -0.4). In multivariate analysis, sTLR4 resulted directly associated with FTI (P = .038). Notably, sTLR4 levels resulted higher in bicarbonate hemodialysis versus hemodiafiltration (0.37 ± 0.18 vs. 0.19 ± 0.21 ng/mL, P < .05).

CONCLUSIONS

sTLR4 correlates with inflammatory and nutritional parameters, presenting as a new potential player in modulating subclinical inflammation in HD patients.

Inflammation down-regulates CYP3A4-catalysed drug metabolism in hemodialysis patients

Background

Recent studies indicate that inflammation may also affect CYP3A4 activity. Associations of CYP3A4-mediated metabolism of quinine, with inflammatory biomarkers were investigated in patients undergoing maintenance hemodialysis (HD).

Methods

A single dose of 100 mg quinine was given to 44 HD patients and the plasma concentration of quinine and its metabolite 3-OH-quinine were measured 12 h after drug intake. The ratios of quinine/3-OH-quinine and 4β-OH-cholesterol/cholesterol were used as markers of CYP3A4 activity. Inflammatory biomarkers, high-sensitive CRP (hsCRP), pentraxin 3 (PTX3) and orosomucoid were followed during 4 weeks prior to quinine administration.

Results

The quinine/3-OH-quinine ratio correlated with median concentrations of hsCRP (Rho = 0.48; p = 0.001) and orosomucoid (Rho = 0.44; p = 0.003), and also with interleukin-6 at 12 h after drug intake (Rho = 0.43; P = 0.004) but not PTX3. In multivariate regression analysis, the correlation between CYP3A4 activity and median hsCRP remained borderline significant (p = 0.05). 4β-OH-cholesterol/cholesterol ratio correlated with quinine/3-OH-quinine (p = 0.008), but not with any of the inflammation markers.

Conclusions

The association between CYP3A4 activity and inflammatory biomarkers suggest that the activity of CYP3A4 is reduced by inflammation in HD patients. Further studies are needed to confirm this finding and to assess to what extent magnitude and duration of inflammation as well as the microbiota affect drug metabolism.