Inflammation and premature aging in advanced chronic kidney disease

Exercise for patients with chronic kidney disease: from cells to systems to function

Chronic kidney disease (CKD) is among the leading causes of death and disability, affecting an estimated 800 million adults globally. The underlying pathophysiology of CKD is complex creating challenges to its management. Primary risk factors for the development and progression of CKD include diabetes mellitus, hypertension, age, obesity, diet, inflammation, and physical inactivity. The high prevalence of diabetes and hypertension in patients with CKD increases the risk for secondary consequences such as cardiovascular disease and peripheral neuropathy. Moreover, the increased prevalence of obesity and chronic levels of systemic inflammation in CKD have downstream effects on critical cellular functions regulating homeostasis. The combination of these factors results in the deterioration of health and functional capacity in those living with CKD. Exercise offers protective benefits for the maintenance of health and function with age, even in the presence of CKD. Despite accumulating data supporting the implementation of exercise for the promotion of health and function in patients with CKD, a thorough description of the responses and adaptations to exercise at the cellular, system, and whole body levels is currently lacking. Therefore, the purpose of this review is to provide an up-to-date comprehensive review of the effects of exercise training on vascular endothelial progenitor cells at the cellular level; cardiovascular, musculoskeletal, and neural factors at the system level; and physical function, frailty, and fatigability at the whole body level in patients with CKD.

Neuroimmune activation and increased brain aging in chronic pain patients after the COVID-19 pandemic onset

The COVID-19 pandemic has exerted a global impact on both physical and mental health, and clinical populations have been disproportionally affected. To date, however, the mechanisms underlying the deleterious effects of the pandemic on pre-existing clinical conditions remain unclear. Here we investigated whether the onset of the pandemic was associated with an increase in brain/blood levels of inflammatory markers and MRI-estimated brain age in patients with chronic low back pain (cLBP), irrespective of their infection history. A retrospective cohort study was conducted on 56 adult participants with cLBP (28 'Pre-Pandemic', 28 'Pandemic') using integrated Positron Emission Tomography/ Magnetic Resonance Imaging (PET/MRI) and the radioligand [11C]PBR28, which binds to the neuroinflammatory marker 18 kDa Translocator Protein (TSPO). Image data were collected between November 2017 and January 2020 ('Pre-Pandemic' cLBP) or between August 2020 and May 2022 ('Pandemic' cLBP). Compared to the Pre-Pandemic group, the Pandemic patients demonstrated widespread and statistically significant elevations in brain TSPO levels (P =.05, cluster corrected). PET signal elevations in the Pandemic group were also observed when 1) excluding 3 Pandemic subjects with a known history of COVID infection, or 2) using secondary outcome measures (volume of distribution -VT- and VT ratio - DVR) in a smaller subset of participants. Pandemic subjects also exhibited elevated serum levels of inflammatory markers (IL-16; P <.05) and estimated BA (P <.0001), which were positively correlated with [11C]PBR28 SUVR (r's ≥ 0.35; P's < 0.05). The pain interference scores, which were elevated in the Pandemic group (P <.05), were negatively correlated with [11C]PBR28 SUVR in the amygdala (r = -0.46; P<.05). This work suggests that the pandemic outbreak may have been accompanied by neuroinflammation and increased brain age in cLBP patients, as measured by multimodal imaging and serum testing. This study underscores the broad impact of the pandemic on human health, which extends beyond the morbidity solely mediated by the virus itself.

Association between dietary inflammatory index and chronic kidney disease in middle-aged and elderly populations

Background

A link between food-induced inflammation and common chronic diseases has been identified in studies. However, there was uncertainty about the influence of dietary inflammatory potential on the risk of chronic kidney disease (CKD) among middle-aged and older groups. Our research aimed to examine the connection between dietary inflammatory index (DII) to CKD in people aged 40 years and older.

Methods

This study comprised ten cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Linear associations of DII with CKD, low-eGFR, and albuminuria were examined using multiple logistic regression, whereas non-linear associations were assessed by smoothed curve fitting. Besides, we conducted subgroup analyses and interaction tests.

Results

Of the 23,175 middle-aged and older individuals, a total of 5,847 suffered from CKD, making up 25.23% of all participants. After adjustment for all covariates, we found that increased DII scores were positive with an increased hazard of CKD (OR = 1.08, 95% CI: 1.05, 1.10, p < 0.0001), and the same was shown between DII and low-eGFR (OR = 1.16, 95% CI: 1.13, 1.19, p < 0.0001). After further converting DII into categorical variables, the above relationship still existed. These relations were consistent in different ages, genders, BMI, whether smoking, whether suffering from hypertension, and whether suffering from diabetes, with no significant stratification differences (all P for interaction >0.05). Surprisingly, we did not find a statistically significant correlation of DII to albuminuria after complete adjustment for covariates (OR = 1.02, 95% CI: 1.00, 1.05, p = 0.0742). Even when DII was considered as a categorical variable, this relation was still not statistically significant. Furthermore, we found an association in the shape of a U between DII and low-eGFR in the fully adjusted model, with a turning point at a DII of 1.6.

Conclusion

Our findings indicated that middle-aged and older persons with greater levels of DII had a significantly higher risk of CKD.

Exploration of Diagnostic Markers Associated with Inflammation in Chronic Kidney Disease Based on WGCNA and Machine Learning

Chronic kidney disease (CKD) is a common disorder related to inflammatory pathways; its effective management remains limited. This study aimed to use bioinformatics analysis to find diagnostic markers that might be therapeutic targets for CKD. CKD microarray datasets were screened from the GEO database and the differentially expressed genes (DEGs) in CKD dataset GSE98603 were analyzed. Gene set variation analysis (GSVA) was used to explore the activity scores of the inflammatory pathways and samples. Algorithms such as weighted gene co-expression network analysis (WGCNA) and Lasso were used to screen CKD diagnostic markers related to inflammation. Then functional enrichment analysis of inflammation-related DEGs was performed. ROC curves were conducted to examine the diagnostic value of inflammation-related hub-genes. Lastly, quantitative real-time PCR further verified the prediction of bioinformatics. A total of 71 inflammation-related DEGs were obtained, of which 5 were hub genes. Enrichment analysis showed that these genes were significantly enriched in inflammation-related pathways (NF-κB, JAK-STAT, and MAPK signaling pathways). ROC curves showed that the 5 CKD diagnostic markers (TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11) also exhibited good diagnostic value. In addition, TIGD7, ACTA2, ACTG2, and HOXA11 expression was downregulated while MAP4K4 expression was upregulated in LPS-induced HK-2 cells. The present study identified TIGD7, ACTA2, ACTG2, MAP4K4, and HOXA11 as reliable CKD diagnostic markers, thereby providing a basis for further understanding of CKD in clinical treatments.

The relationship between dietary inflammatory index and osteoporosis among chronic kidney disease population

Dietary inflammation index (DII) is an epidemiological survey tool to evaluate dietary inflammation potential. Osteoporosis, whose development is deeply affected by inflammation, may be also affected by dietary inflammatory patterns. However, the relationship between DII and osteoporosis is unclear for chronic kidney disease (CKD) population. Our study involved 526 CKD patients from the US National Health and Nutrition Examination Survey (NHANES). DII levels were stratified into four quantile groups. Multivariable regression models were used to examine the association between DII and osteoporosis. Restricted cubic splines and subgroup analysis were additionally adopted. Results showed that the overall prevalence of osteoporosis among CKD patients was 25.3%. After fully adjusted, OR (95% confidence interval) for Q4 group compared with Q3 (reference group) in total and female population were 2.09 (1.05, 4.23) and 2.80 (1.14, 7.08), respectively. Subgroup analysis indicated that these results had no interaction with age, gender, body mass index (BMI), renal function, urinary protein, calcium, phosphorus and total 25-hydroxyvitamin D. DII was negatively correlated with lumbar spine bone mineral density (BMD) in CKD population (P < 0.05). Therefore, in CKD patients, higher DII was associated with higher osteoporosis risk and lower BMD of lumber spine, especially in female. Anti-inflammatory diet patterns may be a protective intervention for some CKD-related osteoporosis.

Renal function in very old critically ill patients

PURPOSE OF REVIEW

Current demographic change leads to higher number of elderly patients admitted to an ICU. Among other organs also the kidneys show age-related changes, which are associated with a decline in various aspects of renal function. The purpose of this review is to provide an overview of structural and functional changes in elderly and also to specifically address the increased risk of acute kidney injury (AKI) in this population.

RECENT FINDINGS

Ageing in the kidneys is affected by many different factors, such as low grade chronic inflammation, called inflammageing, and various comorbidities. Nevertheless, a decrease of glomerular filtration rate (GFR) occurs independent of the presence of comorbidities and a steady decline of GFR has been reported in both healthy men and women. Pharmacodynamic of many drugs is altered by these changes. Additionally the rate of diuretic resistance appears to be increased. The cause of AKI occurrence in older age is, multifactorial and includes preventable triggers (hypovolemia, hypotension, nephrotoxins) as well as changes associated with aging.

SUMMARY

Age-related alterations of the kidneys were found at microscopic and macroscopic levels of the cell. These changes lead to a reduced renal reserve and subsequently to an increased vulnerability of aged kidneys when an additional stressor is added. Age is an independent risk factor for developing AKI. Physicians should take into account the altered renal function in elderly patients and take renal protective measures at an early stage.

Molecular Mechanisms Associated with Aging Kidneys and Future Perspectives

The rapid growth of the elderly population is making the need for extensive and advanced information about age-related organ dysfunction a crucial research area. The kidney is one of the organs most affected by aging. Aged kidneys undergo functional decline, characterized by a reduction in kidney size, decreased glomerular filtration rate, alterations in renal blood flow, and increased inflammation and fibrosis. This review offers a foundation for understanding the functional and molecular mechanisms of aging kidneys and for selecting identifying appropriate targets for future treatments of age-related kidney issues.

Identification of Immune-Related Genes as Biomarkers for Uremia

Purpose

Uremia, which is characterized by immunodeficiency, is associated with the deterioration of kidney function. Immune-related genes (IRGs) are crucial for uremia progression.

Methods

The co-expression network was constructed to identify key modular genes associated with uremia. IRGs were intersected with differentially expressed genes (DEGs) between uremia and control groups and key modular genes to obtain differentially expressed IRGs (DEIRGs). DEIRGs were subjected to functional enrichment analysis. The protein-protein interaction (PPI) network was constructed. The candidate genes were identified using the cytoHubba tool. The biomarkers were identified using various machine learning algorithms. The diagnostic value of the biomarkers was evaluated using receiver operating characteristic (ROC) analysis. The immune infiltration analysis was implemented. The biological pathways of biomarkers were identified using gene set enrichment analysis and ingenuity pathway analysis. The mRNA expression of biomarkers was validated using blood samples of patients with uremia and healthy subjects with quantitative real-time polymerase chain reaction (qRT-PCR).

Results

In total, four biomarkers (PDCD1, NGF, PDGFRB, and ZAP70) were identified by machine learning methods. ROC analysis demonstrated that the area under the curve values of individual biomarkers were > 0.9, indicating good diagnostic power. The nomogram model of biomarkers exhibited good predictive power. The proportions of six immune cells significantly varied between the uremia and control groups. ZAP70 expression was positively correlated with the proportions of resting natural killer (NK) cells, naïve B cells, and regulatory T cells. Functional enrichment analysis revealed that the biomarkers were mainly associated with translational function and neuroactive ligand-receptor interaction. ZAP70 regulated NK cell signaling. The PDCD1 and NGF expression levels determined using qRT-PCR were consistent with those determined using bioinformatics analysis.

Conclusion

PDCD1, NGF, PDGFRB, and ZAP70 were identified as biomarkers for uremia, providing a theoretical foundation for uremia diagnosis.

Screening of key genes in the pathogenesis of muscle atrophy in CKD-PEW children based on RNA sequencing

BACKGROUND

In children with CKD, Protein Energy Wasting (PEW) is common, which affects the outcome of children and is an important cause of poor prognosis. We are aiming to explore the pathogenesis of muscle wasting in CKD-PEW children.

METHODS

Blood samples of 32 children diagnosed with chronic kidney disease (CKD) and protein energy wasting (PEW) in our hospital from January 2016 to June 2021 were collected. RNA sequencing and bioinformatics analysis were performed.

RESULTS

Based on GO (Gene Ontology) functional enrichment analysis, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis and differential gene expression analysis, a total of 25 CKD-PEW related genes were obtained including CRP, IL6, TNF, IL1B, CXCL8, IL12B, IL12A, IL18, IL1A, IL4, IL10, TGFB2, TGFB1, TGFB3, ADIPOQ, NAMPT, RETN, RETNLB, LEP, CD163, ICAM1, VCAM1, SELE, NF-κB1, NF-κB2. The most significantly differentially expressed gene was NF-κB2 (adjusted P = 2.81 × 10-16), and its expression was up-regulated by 3.92 times (corresponding log2FoldChange value was 1.979). Followed by RETN (adjusted P = 1.63 × 10-7), and its expression was up-regulated by 8.306 times (corresponding log2FoldChange value was 2.882). SELE gene were secondly significant (adjusted P = 5.81 × 10-7), and its expression was down-regulated by 22.05 times (corresponding log2FoldChange value was -4.696).

CONCLUSIONS

A variety of inflammatory factors are involved in the pathogenesis of CKD-PEW in children, and chronic inflammation may lead to the development of muscle atrophy in CKD-PEW. It is suggested for the first time that NF-κB is a key gene in the pathogenesis of muscle wasting in CKD-PEW children, and its increased expression may play an important role in the pathogenesis of muscle wasting in children with CKD-PEW.

Distribution characteristics of circulating B cell subpopulations in patients with chronic kidney disease

This study compared the levels of circulating B cell subpopulations in patients with different stages of chronic kidney disease (CKD), investigated the effects of haemodialysis (HD) on the B cell-related immune spectrum in patients with end-stage renal disease, and evaluated the link between renal function and immune homeostasis. Overall, 197 patients with CKD (158 non-dialysis patients with CKD stages I-V and 39 end-stage patients undergoing maintenance HD) and 77 healthy controls were included. Compared to healthy controls, patients with CKD stages I-II showed no significant differences except for the proportion of transitional B cells; patients with CKD stage V showed a significant decrease in the proportions of transitional B cells and CD5+ B cells and a significant increase in double-negative (DN) B cells. Compared with early-stage patients with CKD, the absolute count of various B cell subpopulations in advanced-stage patients with CKD showed a significant decrease. The distribution of circulating B cell subpopulations in patients with CKD was significantly altered and was associated with CKD progression. Furthermore, the proportion of DN B cells and CD5+ B cells was inconsistent pre- and post-HD. This in-depth study of the immune status of patients with CKD may have important clinical value.

Effects of Polydextrose Supplementation on Intestinal Function in Hemodialysis Patients: A Double-Blind, Randomized, Placebo-Controlled Trial

OBJECTIVES

Intestinal constipation is a frequent complication in hemodialysis (HD) patients. Polydextrose (PDX), a nondigestible oligosaccharide, has been reported as a fermentable fiber with potential benefits. This study aimed to investigate the possible influence of PDX supplementation on intestinal function in HD patients.

METHODS

This randomized, double-blind, placebo-controlled trial included 28 patients who received daily oral supplementation with 12 g of PDX or placebo (corn starch) for 2 months. ROME IV criteria were used to define constipation and questionnaires were applied to patient assessment of constipation symptoms (PAC-SYM) and their impact on the patient assessment of constipation quality of life. The Bristol scale was used to assess stool consistency. Commercial Enzyme-Linked Immuno Sorbent Assay kits were used to evaluate the interleukin-6 and tumor necrosis factor-α plasma levels.

RESULTS

25 patients completed the study; 16 in the PDX group [7 females, 48.5 years (IQR = 15.5)] and 9 in the control group [3 females, 44.0 years (IQR = 6.0)]. According to ROME IV criteria, 55% of patients were diagnosed with constipation. PAC-SYM faecal symptoms domain was reduced after 2 months of PDX supplementation (P = .004). We also observed a significant reduction in the PAC-QoL-concerns domain (P = .02). The average values for PAC-SYM and patient assessment of constipation quality of lifewere reduced significantly after intervention with PDX. There were no significant changes after the intervention period concerning biochemical variables, food intake, and inflammation markers. No adverse effects were observed during the supplementation period.

CONCLUSIONS

The results of the present study suggest that short-term PDX supplementation may have favourable results on intestinal function and the quality of life of chronic kidney disease patients in HD.

Inflammation and gut dysbiosis as drivers of CKD-MBD

Two decades ago, Kidney Disease: Improving Global Outcomes coined the term chronic kidney disease-mineral and bone disorder (CKD-MBD) to describe the syndrome of biochemical, bone and extra-skeletal calcification abnormalities that occur in patients with CKD. CKD-MBD is a prevalent complication and contributes to the excessively high burden of fractures and cardiovascular disease, loss of quality of life and premature mortality in patients with CKD. Thus far, therapy has focused primarily on phosphate retention, abnormal vitamin D metabolism and parathyroid hormone disturbances, but these strategies have largely proved unsuccessful, thus calling for paradigm-shifting concepts and innovative therapeutic approaches. Interorgan crosstalk is increasingly acknowledged to have an important role in health and disease. Accordingly, mounting evidence suggests a role for both the immune system and the gut microbiome in bone and vascular biology. Gut dysbiosis, compromised gut epithelial barrier and immune cell dysfunction are prominent features of the uraemic milieu. These alterations might contribute to the inflammatory state observed in CKD and could have a central role in the pathogenesis of CKD-MBD. The emerging fields of osteoimmunology and osteomicrobiology add another level of complexity to the pathogenesis of CKD-MBD, but also create novel therapeutic opportunities.

Causal effects of systemic inflammatory regulators on chronic kidney diseases and renal function: a bidirectional Mendelian randomization study

Background

While targeted systemic inflammatory modulators show promise in preventing chronic kidney disease (CKD) progression, the causal link between specific inflammatory factors and CKD remains uncertain.

Methods

Using a genome-wide association study of 41 serum cytokines from 8,293 Finnish individuals, we conducted a bidirectional two-sample Mendelian randomization (MR) analysis. In addition, we genetically predicted causal associations between inflammatory factors and 5 phenotypes, including CKD, estimated glomerular filtration rate (eGFR), dialysis, rapid progression of CKD, and rapid decline in eGFR. Inverse variance weighting (IVW) served as the primary MR method, while MR-Egger, weighted median, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were utilized for sensitivity analysis. Cochrane's Q test for heterogeneity. Leave-one-out method ensured stability of MR results, and Bonferroni correction assessed causal relationship strength.

Results

Seventeen cytokines were associated with diverse renal outcomes. Among them, after Bonferroni correction test, higher tumor necrosis factor alpha levels were associated with a rapid decrease in eGFR (OR = 1.064, 95% CI 1.028 - 1.103, P = 0.001), higher interleukin-4 levels were associated with an increase in eGFR (β = 0.003, 95% CI 0.001 - 0.005, P = 0.002), and higher growth regulated oncogene alpha (GROα) levels were associated with an increased risk of CKD (OR=1.035, 95% CI 1.012 - 1.058, P = 0.003). In contrast, genetic susceptibility to CKD was associated with an increase in GROa, and a decrease in eGFR may lead to an increase in stem cell factor. We did not find the presence of horizontal pleiotropy during the analysis.

Conclusion

We discovered causally related inflammatory factors that contribute to the initiation and progression of CKD at the genetic prediction level.

The Contribution of Muscle Innate Immunity to Uremic Cachexia

Protein energy wasting (PEW) is a common complication both in chronic kidney disease (CKD) and end-stage kidney disease (ESKD). Of note, PEW is one of the stronger predictors of morbidity and mortality in this patient population. The pathogenesis of PEW involves several mechanisms, including anorexia, insulin resistance, acidosis and low-grade inflammation. In addition, "sterile" muscle inflammation contributes to PEW at an advanced CKD stage. Both immune and resident muscle cells can activate innate immunity; thus, they have critical roles in triggering "sterile" tissue inflammation. Toll-like receptor 4 (TLR4) can detect endogenous danger-associated molecular patterns generated or retained in blood in uremia and induce a sterile muscle inflammatory response via NF-κB in myocytes. In addition, TLR4, though the activation of the NLRP3 inflammasome, links the sensing of metabolic uremic stress in muscle to the activation of pro-inflammatory cascades, which lead to the production of IL-1β and IL-18. Finally, uremia-induced accelerated cell senescence is associated with a secretory phenotype that favors fibrosis in muscle. Targeting these innate immune pathways could lead to novel therapies for CKD-related PEW.

Transcatheter Aortic Valve Implantation versus Surgical Aortic Valve Replacement in Chronic Kidney Disease: Meta-Analysis of Reconstructed Time-to-Event Data

BACKGROUND

Patients with advanced chronic kidney disease (CKD) are a challenging and understudied population. Specifically, the late outcomes following surgical aortic valve replacement (SAVR) or transcatheter aortic valve implantation (TAVI) in patients with CKD remains uncertain.

OBJECTIVES

To compare overall mortality risk in patients with moderate-to-severe CKD following TAVI versus SAVR.

METHODS

Study-level meta-analysis of reconstructed time-to-event data from Kaplan-Meier curves of studies published by August 2022.

RESULTS

Nine studies met our inclusion criteria. Patients who underwent TAVI had a higher 5-year mortality compared with patients undergoing SAVR in the overall population (HR 1.56, 95% CI 1.44-1.69, P<0.001) and in populations with similar risk scores (HR 1.15, 95% CI 1.01-1.31, P=0.035). The landmark analysis revealed a lower risk of 30-day mortality with TAVI (HR 0.62, 95% CI 0.41-0.94, P=0.023), followed by similar risk until 7.5 months (HR 1, 95% CI 0.78-1.27, P=0.978). In contrast, the landmark analysis beyond 7.5 months yielded a reversal of the HR in favor of SAVR (TAVI with HR 1.27, 95% CI 1.08-1.49 P=0.003).

CONCLUSIONS

In patients with CKD, TAVI provides an initial survival benefit over SAVR. However, in the long run, a significant survival benefit of SAVR over TAVI was observed. Our findings highlight the need for randomized controlled trials to investigate outcomes in this special population.

Differential Methylation of Telomere-Related Genes Is Associated with Kidney Disease in Individuals with Type 1 Diabetes

Diabetic kidney disease (DKD) represents a major global health problem. Accelerated ageing is a key feature of DKD and, therefore, characteristics of accelerated ageing may provide useful biomarkers or therapeutic targets. Harnessing multi-omics, features affecting telomere biology and any associated methylome dysregulation in DKD were explored. Genotype data for nuclear genome polymorphisms in telomere-related genes were extracted from genome-wide case-control association data (n = 823 DKD/903 controls; n = 247 end-stage kidney disease (ESKD)/1479 controls). Telomere length was established using quantitative polymerase chain reaction. Quantitative methylation values for 1091 CpG sites in telomere-related genes were extracted from epigenome-wide case-control association data (n = 150 DKD/100 controls). Telomere length was significantly shorter in older age groups (p = 7.6 × 10^-6). Telomere length was also significantly reduced (p = 6.6 × 10^-5) in DKD versus control individuals, with significance remaining after covariate adjustment (p = 0.028). DKD and ESKD were nominally associated with telomere-related genetic variation, with Mendelian randomisation highlighting no significant association between genetically predicted telomere length and kidney disease. A total of 496 CpG sites in 212 genes reached epigenome-wide significance (p ≤ 10^-8) for DKD association, and 412 CpG sites in 193 genes for ESKD. Functional prediction revealed differentially methylated genes were enriched for Wnt signalling involvement. Harnessing previously published RNA-sequencing datasets, potential targets where epigenetic dysregulation may result in altered gene expression were revealed, useful as potential diagnostic and therapeutic targets for intervention.

Accelerated Vascular Aging in Chronic Kidney Disease: The Potential for Novel Therapies

The pathophysiology of vascular disease is linked to accelerated biological aging and a combination of genetic, lifestyle, biological, and environmental risk factors. Within the scenario of uncontrolled artery wall aging processes, CKD (chronic kidney disease) stands out as a valid model for detailed structural, functional, and molecular studies of this process. The cardiorenal syndrome relates to the detrimental bidirectional interplay between the kidney and the cardiovascular system. In addition to established risk factors, this group of patients is subjected to a plethora of other emerging vascular risk factors, such as inflammation, oxidative stress, mitochondrial dysfunction, vitamin K deficiency, cellular senescence, somatic mutations, epigenetic modifications, and increased apoptosis. A better understanding of the molecular mechanisms through which the uremic milieu triggers and maintains early vascular aging processes, has provided important new clues on inflammatory pathways and emerging risk factors alike, and to the altered behavior of cells in the arterial wall. Advances in the understanding of the biology of uremic early vascular aging opens avenues to novel pharmacological and nutritional therapeutic interventions. Such strategies hold promise to improve future prevention and treatment of early vascular aging not only in CKD but also in the elderly general population.

Endothelial Cell Dysfunction and Increased Cardiovascular Risk in Patients With Chronic Kidney Disease

The endothelium is considered to be the gatekeeper of the vessel wall, maintaining and regulating vascular integrity. In patients with chronic kidney disease, protective endothelial cell functions are impaired due to the proinflammatory, prothrombotic and uremic environment caused by the decline in kidney function, adding to the increase in cardiovascular complications in this vulnerable patient population. In this review, we discuss endothelial cell functioning in healthy conditions and the contribution of endothelial cell dysfunction to cardiovascular disease. Further, we summarize the phenotypic changes of the endothelium in chronic kidney disease patients and the relation of endothelial cell dysfunction to cardiovascular risk in chronic kidney disease. We also review the mechanisms that underlie endothelial changes in chronic kidney disease and consider potential pharmacological interventions that can ameliorate endothelial health.

Harnessing Genomic Analysis to Explore the Role of Telomeres in the Pathogenesis and Progression of Diabetic Kidney Disease

The prevalence of diabetes is increasing globally, and this trend is predicted to continue for future decades. Research is needed to uncover new ways to manage diabetes and its co-morbidities. A significant secondary complication of diabetes is kidney disease, which can ultimately result in the need for renal replacement therapy, via dialysis or transplantation. Diabetic kidney disease presents a substantial burden to patients, their families and global healthcare services. This review highlights studies that have harnessed genomic, epigenomic and functional prediction tools to uncover novel genes and pathways associated with DKD that are useful for the identification of therapeutic targets or novel biomarkers for risk stratification. Telomere length regulation is a specific pathway gaining attention recently because of its association with DKD. Researchers are employing both observational and genetics-based studies to identify telomere-related genes associated with kidney function decline in diabetes. Studies have also uncovered novel functions for telomere-related genes beyond the immediate regulation of telomere length, such as transcriptional regulation and inflammation. This review summarises studies that have revealed the potential to harness therapeutics that modulate telomere length, or the associated epigenetic modifications, for the treatment of DKD, to potentially slow renal function decline and reduce the global burden of this disease.

Accelerated AGEing: The Impact of Advanced Glycation End Products on the Prognosis of Chronic Kidney Disease

Advanced glycation end products (AGEs) are aging products. In chronic kidney disease (CKD), AGEs accumulate due to the increased production, reduced excretion, and the imbalance between oxidant/antioxidant capacities. CKD is therefore a model of aging. The aim of this review is to summarize the present knowledge of AGEs in CKD onset and progression, also focusing on CKD-related disorders (cardiovascular diseases, sarcopenia, and nutritional imbalance) and CKD mortality. The role of AGEs as etiopathogenetic molecules, as well as potential markers of disease progression and/or therapeutic targets, will be discussed.

Comparison of the association between six different frailty scales and clinical events in patients on hemodialysis

BACKGROUND

Frailty is associated with adverse outcomes in patients undergoing hemodialysis (HD). However, no study has used various frailty assessments in patients on HD to examine their association with clinical events. In this study, we investigated the association between clinical events and six frailty scales.

METHODS

Outpatients who underwent HD between 2018 and 2020 were retrospectively enrolled. Frailty was defined using the Fried Frailty Phenotype, Study of Osteoporotic Fractures (SOF) Index, Short Physical Performance Battery (SPPB), Frail Screening Index, FRAIL scale and Clinical Frailty Scale. Outcomes were clinical events, including a composite of multiple (i.e. recurrent) all-cause hospitalizations, fractures and/or all-cause mortality. The association of clinical events and the frailty scales were investigated using negative binomial regression analysis.

RESULTS

Fried Frailty Phenotype [incident rate ratio (IRR), 1.62; 95% confidence interval (CI), 1.49-1.76], SOF Index (IRR, 1.42; 95% CI, 1.10-1.83), SPPB (IRR, 1.79; 95% CI, 1.11-2.88) and Clinical Frailty Scale (IRR, 1.65; 95% CI, 1.04-2.61) were significantly associated with clinical events. However, Frail Screening Index (IRR, 1.38; 95% CI, 0.60-3.18) and FRAIL scale (IRR, 1.30; 95% CI, 0.88-1.92) showed no significant association with clinical events.

CONCLUSIONS

Objective frailty assessments (SPPB) and medical staff impression-based frailty (Clinical Frailty Scale) may be useful prognostic predictors for patients on HD. Questionnaire-based frailty assessment should be carefully considered when used as a measurement of frailty.

Effect of frailty, physical performance, and chronic kidney disease on mortality in older patients with diabetes : a retrospective longitudinal cohort study

BACKGROUND

Declined renal function is associated with physical function impairment and frailty in a graded fashion. This study aimed to examine the relationship between renal function, frailty and physical performance with mortality in older patients with diabetes, while also determining their combined effects on patient outcome.

METHODS

A retrospective longitudinal study was conducted in elderly patients with diabetes. Kidney disease staging was based on clinical practice guidelines of the International Society of Nephrology, and chronic kiney disease (CKD) was defined as urinary albumin to creatinine ratio (UACR) > 30 mg/g, persistent reduction in estimated glomerular filtration rate (eGFR) below 60 mL/min per 1.73 m² or both. The modified Rockwood frailty index (RFI) was composed of cumulative health deficits, and physical function was determined by handgrip strength (HGS). Additionally, a timed up and go (TUG) test was assessed at baseline. Kaplan-Meier survival and Cox proportional hazard analyses were used to analyze the association between CKD, frailty, physical function and mortality.

RESULTS

For the 921 enrolled patients, their mean age was 82.0 ± 6.7 years. After a median 2.92 (interquartile range [IQR] 1.06-4.43) year follow-up, the survival rate was 67.6% and 85.5% in patients with and without CKD, respectively. The mortality hazard ratio (crude HR) with CKD was 5.92 for those with an RFI higher than 0.313 (95% CI 3.44-10.18), 2.50 for a TUG time longer than 21 s (95% CI 1.22-5.13), and 2.67 for an HGS lower than 10.57 kg in females or 20.4 kg in males (95% CI 1.12-6.37). After multivariate adjustment, the mortality hazard ratio for an RFI ≥ 0.313 was 5.34 (95% CI 2.23-12.80) in CKD patients, but not in patients without CKD. In subgroup analysis, patients experiencing CKD and frailty, or physical function impairment, had the lowest survival proportion followed by only frailty/declined physical function, only CKD, without CKD, and non-frailty/non-physical impairment.

CONCLUSION

CKD, frailty and physical function impairment were all associated with an increased mortality risk in older patients with diabetes, while the combined effects of these 3 factors were seen on patient outcome.

Chronic Kidney Disease and the Exposome of Ageing

The gap between improvements in lifespan and age-related health is widening. Globally, the demographic of ageing is increasing and there has emerged a 'diseasome of ageing', typified by a range of non-communicable diseases which share a common underlying component of a dysregulated ageing process. Within this, chronic kidney disease is an emerging global epidemic.The extensive inter-individual variation displayed in how people age and how their diseasome manifests and progresses, has required a renewed focus on their life course exposures and the interplay between the environment and the (epi)genome. Termed the exposome, life course abiotic and biotic factors have a significant impact on renal health.We explore how the exposome of renal ageing can predispose and affect CKD progression. We discuss how the kidney can be used as a model to understand the impact of the exposome in health and chronic kidney disease and how this might be manipulated to improve health span.Notably, we discuss the manipulation of the foodome to mitigate acceleration of ageing processes by phosphate and to explore use of emerging senotherapies. A range of senotherapies, for removing senescent cells, diminishing inflammatory burden and either directly targeting Nrf2, or manipulating it indirectly via modification of the microbiome are discussed.

Frailty and Humoral Immune Responses Following COVID-19 Vaccination among Patients Undergoing Hemodialysis

BACKGROUND

Patients with end-stage kidney disease who are undergoing dialysis have reduced immune responses to COVID-19 vaccination. Frailty is extremely common among dialysis patients and may contribute to the impaired immunogenicity. This study aimed to determine the association between frailty and humoral immune responses following COVID-19 vaccination in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS

Adult hemodialysis patients without prior SARS-CoV-2 infection who received a priming dose of ChAdOx1 nCoV-19, an adenovirus-vectored vaccine, were assessed for eligibility. Participants were categorized as robust, pre-frail, or frail using the Fried frailty criteria. Humoral responses were assessed 28 days after vaccination by measuring titers of anti-spike IgG antibodies. The primary outcome was anti-spike antibody seroconversion, defined as antibody levels ≥50 AU/mL. Multivariable-adjusted logistic regression models were used to assess the association between frailty status and the primary outcome.

RESULTS

A total of 206 participants (mean age 67 ± 13 years, 50% women) were included in the study, of whom 50 (24%) were characterized as frail, 86 (42%) were characterized as pre-frail, and 70 (34%) were characterized as robust. Anti-spike antibody levels were progressively lower with more advanced stages of frailty (P <0.001). Compared with robust patients, a significantly smaller proportion of pre-frail and frail patients developed anti-spike antibody seroconversion (87%, 66%, and 40%, respectively; P <0.001). Frailty was associated with the absence of humoral responses after adjustment for age, sex, body mass index, diabetes, coronary artery disease, serum albumin, and lymphocyte count (OR=0.25; 95% CI, 0.08-0.80).

CONCLUSIONS

Frailty is independently associated with impaired humoral responses following COVID-19 vaccination among hemodialysis patients. Strategies aimed at preventing or attenuating frailty in the dialysis population are warranted.

NAD+ Metabolism and Interventions in Premature Renal Aging and Chronic Kidney Disease

Premature aging causes morphological and functional changes in the kidney, leading to chronic kidney disease (CKD). CKD is a global public health issue with far-reaching consequences, including cardio-vascular complications, increased frailty, shortened lifespan and a heightened risk of kidney failure. Dialysis or transplantation are lifesaving therapies, but they can also be debilitating. Currently, no cure is available for CKD, despite ongoing efforts to identify clinical biomarkers of premature renal aging and molecular pathways of disease progression. Kidney proximal tubular epithelial cells (PTECs) have high energy demand, and disruption of their energy homeostasis has been linked to the progression of kidney disease. Consequently, metabolic reprogramming of PTECs is gaining interest as a therapeutic tool. Preclinical and clinical evidence is emerging that NAD⁺ homeostasis, crucial for PTECs' oxidative metabolism, is impaired in CKD, and administration of dietary NAD⁺ precursors could have a prophylactic role against age-related kidney disease. This review describes the biology of NAD⁺ in the kidney, including its precursors and cellular roles, and discusses the importance of NAD⁺ homeostasis for renal health. Furthermore, we provide a comprehensive summary of preclinical and clinical studies aimed at increasing NAD⁺ levels in premature renal aging and CKD.

Structural and Functional Changes in Aging Kidneys

The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis. Apart from physiological changes, there are some conditions such as hypertension, diabetes or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening. The principal aspect of stopping unfavorable changes is to maintain health. Studies have shown many useful ways to mitigate renal aging. This review is focused especially on medications such as renin-angiotensin-aldosterone system blockers or resveratrol, but even eating habits and lifestyle.

An updated clinical prediction model of protein-energy wasting for hemodialysis patients

Background and aim

Protein-energy wasting (PEW) is critically associated with the reduced quality of life and poor prognosis of hemodialysis patients. However, the diagnosis criteria of PEW are complex, characterized by difficulty in estimating dietary intake and assessing muscle mass loss objectively. We performed a cross-sectional study in hemodialysis patients to propose a novel PEW prediction model.

Materials and methods

A total of 380 patients who underwent maintenance hemodialysis were enrolled in this cross-sectional study. The data were analyzed with univariate and multivariable logistic regression to identify influencing factors of PEW. The PEW prediction model was presented as a nomogram by using the results of logistic regression. Furthermore, receiver operating characteristic (ROC) and decision curve analysis (DCA) were used to test the prediction and discrimination ability of the novel model.

Results

Binary logistic regression was used to identify four independent influencing factors, namely, sex (P = 0.03), triglycerides (P = 0.009), vitamin D (P = 0.029), and NT-proBNP (P = 0.029). The nomogram was applied to display the value of each influencing factor contributed to PEW. Then, we built a novel prediction model of PEW (model 3) by combining these four independent variables with part of the International Society of Renal Nutrition and Metabolism (ISRNM) diagnostic criteria including albumin, total cholesterol, and BMI, while the ISRNM diagnostic criteria served as model 1 and model 2. ROC analysis of model 3 showed that the area under the curve was 0.851 (95%CI: 0.799-0.904), and there was no significant difference between model 3 and model 1 or model 2 (all P > 0.05). DCA revealed that the novel prediction model resulted in clinical net benefit as well as the other two models.

Conclusion

In this research, we proposed a novel PEW prediction model, which could effectively identify PEW in hemodialysis patients and was more convenient and objective than traditional diagnostic criteria.

Inflammaging: Implications in Sarcopenia

In a world in which life expectancy is increasing, understanding and promoting healthy aging becomes a contemporary demand. In the elderly, a sterile, chronic and low-grade systemic inflammation known as "inflammaging" is linked with many age-associated diseases. Considering sarcopenia as a loss of strength and mass of skeletal muscle related to aging, correlations between these two terms have been proposed. Better knowledge of the immune system players in skeletal muscle would help to elucidate their implications in sarcopenia. Characterizing the activators of damage sensors and the downstream effectors explains the inference with skeletal muscle performance. Sarcopenia has also been linked to chronic diseases such as diabetes, metabolic syndrome and obesity. Implications of inflammatory signals from these diseases negatively affect skeletal muscle. Autophagic mechanisms are closely related with the inflammasome, as autophagy eliminates stress signaling sent by damage organelles, but also acts with an immunomodulatory function affecting immune cells and cytokine release. The use of melatonin, an antioxidant, ROS scavenger and immune and autophagy modulator, or senotherapeutic compounds targeting senescent cells could represent strategies to counteract inflammation. This review aims to present the many factors regulating skeletal muscle inflammaging and their major implications in order to understand the molecular mechanisms involved in sarcopenia.

Turmeric supplementation with piperine is more effective than turmeric alone in attenuating oxidative stress and inflammation in hemodialysis patients: A randomized, double-blind clinical trial

PURPOSE

Turmeric has renop rotective effects that can act to reduce oxidative stress and inflammation in hemodialysis (HD) patients. Piperine has been indicated as a bioavailability enhancer of turmeric and consequently of its biological effects. However, data on the efficacy of the turmeric/piperine combination in HD patients are limited. We aimed to verify whether turmeric supplementation in combination with piperine has a superior effect to turmeric alone in increasing antioxidant capacity and reducing oxidative stress and inflammation in HD patients.

METHODS

This randomized, double-blind clinical trial was conducted in HD patients (age 20-75 years). Patients were supplemented with turmeric (3 g/day) or turmeric/piperine (3 g turmeric + 2 mg piperine/day) for 12 weeks. Malondialdehyde (MDA), antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), high-sensitivity C-reactive protein (hs-CRP), and ferritin were evaluated at baseline and the end of the study.

RESULTS

There was a reduction in the MDA and ferritin levels in the turmeric/piperine group and in the comparison between groups at the end of the study [MDA: -0.08(-0.14/0.01) nmol/mL versus -0.003(-0.10/0.26) nmol/mL, p = 0.003; ferritin: -193.80 ± 157.29 mg/mL versus 51.99 ± 293.25 mg/mL, p = 0.018]. In addition, GPx activity reduced in the turmeric group (p = 0.029). No changes were observed for CAT, GR, and hs-CRP.

CONCLUSION

Turmeric plus piperine was superior to turmeric alone in decreasing MDA and ferritin levels. The use of a combination of turmeric and piperine as a dietary intervention may be beneficial for modulating the status oxidative and inflammation in HD patients.

BRAZILIAN REGISTRY OF CLINICAL TRIALS NUMBER

RBR-2t5zpd; Registration Date: May 2, 2018.

Efficacy of neuromuscular electrical stimulation with combined low and high frequencies on body composition, peripheral muscle function and exercise tolerance in patients with chronic kidney disease undergoing haemodialysis: a protocol for a randomised, double-blind clinical trial

INTRODUCTION

Neuromuscular electrical stimulation (NMES) as an adjunctive strategy to increase isolated muscular strength or endurance has been widely investigated in patients with chronic kidney disease (CKD) undergoing haemodialysis (HD). However, the efficacy of combined low and high frequencies, to improve both muscular strength and endurance, is unknown. This trial aims to evaluate the efficacy of this combined NMES strategy in this population.

METHODS AND ANALYSIS

This is a randomised controlled trial with blinded assessments and analysis. A total of 56 patients with CKD undergoing HD will be recruited and randomised to an NMES protocol. The evaluations will be performed on three different days at baseline and after 24 sessions of follow-up. Assessments will include the background, insulin-like growth factor, lactate measurement, malnutrition and inflammation score evaluation, an electrical bioimpedance examination, global muscular evaluation by means of the Medical Research Council scale, handgrip strength evaluation, muscular isokinetic evaluation of lower limbs, 6 min step test performance and quality of life (QoL) questionnaire with emphasis on physical function. The patients will be allocated in one of the following four groups: 1) combined low and high frequencies; 2) low frequency; 3) high frequency; and 4) sham stimulation with minimal intensity to generate only sensory perception (with no visible contraction). In all groups, the intensity throughout the session will be the highest tolerated by patient (except for control group). The primary endpoint is the change of peripheral muscle function (muscular strength and endurance). The secondary endpoints will be the changes of body composition; muscle trophism; exercise tolerance; QoL; and nutritional, inflammatory, and metabolic markers. The findings of this study are expected to provide valuable knowledge on how to optimise the NMES intervention, with improvements in both muscle strength and endurance.

ETHICS AND DISSEMINATION

This protocol has been approved by the Ethics Committee on Research with Humans of Hospital Sírio-Libanês (approval no. 24337707). Written informed consent will be obtained from each participant. The results of the study will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03779126.

Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney Disease

Chronic kidney disease (CKD) is a progressive disease that affects millions of adults every year. Major risk factors include diabetes, hypertension, and obesity, which affect millions of adults worldwide. CKD is characterized by cellular injury followed by permanent loss of functional nephrons. As injured cells die and nephrons become sclerotic, remaining healthy nephrons attempt to compensate by undergoing various structural, molecular, and functional changes. While these changes are designed to maintain appropriate renal function, they may lead to additional cellular injury and progression of disease. As CKD progresses and filtration decreases, the ability to eliminate metabolic wastes and environmental toxicants declines. The inability to eliminate environmental toxicants such as arsenic, cadmium, and mercury may contribute to cellular injury and enhance the progression of CKD. The present review describes major molecular alterations that contribute to the pathogenesis of CKD and the effects of arsenic, cadmium, and mercury on the progression of CKD.

Frailty in end stage renal disease: Current perspectives

Frailty is common in end stage renal disease (ESRD) and is a marker of poor outcomes. Its prevalence increases as chronic kidney disease (CKD) progresses. There are different measurement tools available to assess frailty in ESRD. The pathogenesis of frailty in ESRD is multifactorial including uraemia and dialysis related factors. In this current review, we discuss the importance of frailty, its pathogenesis, screening methods, prognostic implications and management strategies in context of ESRD.

Inflammation: Roles in Skeletal Muscle Atrophy

Various diseases can cause skeletal muscle atrophy, usually accompanied by inflammation, mitochondrial dysfunction, apoptosis, decreased protein synthesis, and enhanced proteolysis. The underlying mechanism of inflammation in skeletal muscle atrophy is extremely complex and has not been fully elucidated, thus hindering the development of effective therapeutic drugs and preventive measures for skeletal muscle atrophy. In this review, we elaborate on protein degradation pathways, including the ubiquitin-proteasome system (UPS), the autophagy-lysosome pathway (ALP), the calpain and caspase pathways, the insulin growth factor 1/Akt protein synthesis pathway, myostatin, and muscle satellite cells, in the process of muscle atrophy. Under an inflammatory environment, various pro-inflammatory cytokines directly act on nuclear factor-κB, p38MAPK, and JAK/STAT pathways through the corresponding receptors, and then are involved in muscle atrophy. Inflammation can also indirectly trigger skeletal muscle atrophy by changing the metabolic state of other tissues or cells. This paper explores the changes in the hypothalamic-pituitary-adrenal axis and fat metabolism under inflammatory conditions as well as their effects on skeletal muscle. Moreover, this paper also reviews various signaling pathways related to muscle atrophy under inflammatory conditions, such as cachexia, sepsis, type 2 diabetes mellitus, obesity, chronic obstructive pulmonary disease, chronic kidney disease, and nerve injury. Finally, this paper summarizes anti-amyotrophic drugs and their therapeutic targets for inflammation in recent years. Overall, inflammation is a key factor causing skeletal muscle atrophy, and anti-inflammation might be an effective strategy for the treatment of skeletal muscle atrophy. Various inflammatory factors and their downstream pathways are considered promising targets for the treatment and prevention of skeletal muscle atrophy.

Telomere attrition and inflammation: the chicken and the egg story

The challenge to improve human life span has progressed with the advent of health care services and technologies. This improvement poses a new challenge of an associated wave of diseases and pathologies that have not been observed or experienced. This has led to rise in geriatric population who are currently facing health challenges that needs to be addressed by the research community. This review focuses primarily on two mechanisms that have contributed to aging and associated pathologies: telomere attrition and inflammatory insults. A strong interplay appears to exist between telomere attrition and inflammation, and this could be the basis of many pathologies associated with increasing age. This creates a scientific dilemma as to what comes first: telomere attrition or inflammation. This review will enthuse the reader to the underlying molecules and mechanisms associated with telomere attrition and inflammation and their contribution to aging.

Food for healthier aging: power on your plate

Inflammageing is a persistent low-level inflammatory burden that accompanies age-related dysregulation of the immune system during normative aging and within the diseasome of aging. A healthy diet containing a balanced amount of macronutrients, vitamins and minerals, adequate in calories and rich in poly(phenols), has an essential role in mitigating the effects of inflammageing and extending healthspan through modulation of the activity of a range of factors. These include transcription factors, such as nuclear factor erythroid-derived 2 related factor 2 (Nrf2) and nuclear factor-κB (NF-kB), the inflammasome and the activities of the gut microbiota. The aim of this narrative review is to discuss the potential of food to ameliorate the effects of the diseasome of aging.

Angiotensin-converting enzyme 2 and transmembrane protease serine 2 in female and male patients with end-stage kidney disease

BACKGROUND

Individuals with chronic kidney disease are affected by acute respiratory syndrome coronavirus 2 (SARS-CoV-2) due to multiple comorbidities and altered immune system. The first step of the infection process is the binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2) receptor, followed by its priming by transmembrane protease serine 2 (TMPRSS2). We hypothesized that circulating soluble ACE2 levels, as well as the expressions of ACE2 and TMPRSS2 in the microvasculature, are increased in patients with end-stage kidney disease (ESKD).

METHODS

A total of 210 participants were enrolled, representing 80 ESKD patients and 73 non-CKD controls for soluble ACE2, and 31 ESKD and 26 non-CKD controls for vasculature and fat tissue bioassays. We have assessed ACE2 expression in blood using ELISA and in tissue using immunofluorescence.

RESULTS

Soluble ACE2 levels were higher in ESKD patients compared to controls; however, there is no sex difference observed. In ESKD and controls, soluble ACE2 positively correlated with Interleukin 6 (IL-6) and C-reactive protein (CRP), respectively. Similarly, ACE2 tissue expression in the vasculature was higher in ESKD patients; moreover, this higher ACE2 expression was observed only in male ESKD patients. In addition, TMPRSS2 expression was observed in vessels from males and females but showed no sex difference. The expression of ACE2 receptor was higher in ESKD patients on ACE-inhibitor/angiotensin blocker treatment.

CONCLUSION

ESKD is associated with increased ACE2 levels in the circulation and pronounced in male vasculature; however, further studies are warranted to assess possible sex differences on specific treatment regime(s) for different comorbidities present in ESKD.

Impacto das diferentes modalidades de diálise peritoneal automatizada sobre o perfil inflamatório de idosos portadores de doença renal crônica

Resumo Introdução: A doença renal crônica, mais prevalente em idosos, é considerada um problema de saúde pública em todo o mundo. Objetivo: Avaliar o impacto das modalidades de diálise peritoneal automatizada, intermitente e contínua, no perfil inflamatório de idosos renais crônicos. Métodos: Estudo prospectivo, transversal e analítico realizado em uma clínica de diálise em Brasília, com 74 idosos com idade igual ou maior que 60 anos. Os pacientes foram submetidos ao Teste de Equilíbrio Peritoneal rápido, avaliação clínica, coleta de sangue para avaliações bioquímicas e de citocinas, interleucina 6 e fator de crescimento transformador beta 1, e questionário de qualidade de vida (KDQOL-SF36). Foram utilizadas para análise dos dados, associações e correlações com nível de significância de 5%. Resultados: Pacientes na modalidade contínua apresentaram valores séricos do fator de crescimento transformador beta 1 maiores do que os em modalidade intermitente. Estes apresentaram fator de crescimento transformador beta 1 no peritônio, idade e função renal residual maiores do que os em modalidade contínua. A dosagem da interleucina 6 no peritônio foi associada à idade, enquanto a IL-6 sérica foi associada à IL-6 no peritônio, ao tempo em diálise e à idade. Não houve associação entre a modalidade e a presença de diabetes, volemia ou estado nutricional. Ambas as modalidades permitem boa adequação à terapia dialítica. Conclusão: A inflamação na diálise peritoneal automatizada está associada principalmente à baixa função renal residual, à idade avançada e ao maior tempo em terapia, e não à modalidade de diálise realizada.

Impact of different automated peritoneal dialysis modalities on the inflammatory profile of elderly patients with chronic kidney disease

INTRODUCTION

Chronic kidney disease, more prevalent in the elderly, is considered a public health issue worldwide.

OBJECTIVE

To evaluate the impact of automated, peritoneal dialysis modalities, intermittent and continuous, on the inflammatory profile of elderly people with chronic kidney disease.

METHODS

Prospective, cross-sectional and analytical study carried out in a dialysis clinic in Brasília - Brazil, with 74 elderly people aged 60 years or older. The patients underwent rapid Peritoneal Equilibration Test, clinical assessment, blood collection for biochemical and cytokine assessments, interleukin 6 and transforming growth factor beta 1, and answered a quality-of-life questionnaire (KDQOL-SF36). We used a 5% significance level for data analysis, associations and correlations.

RESULTS

Patients in the continuous modality had higher serum values of transforming growth factor beta 1 than those in the intermittent modality, which had higher peritoneal transforming growth factor beta 1, age and residual renal function than those in continuous mode. Interleukin 6 dosage in the peritoneum was associated with age, while serum IL-6 was associated with IL-6 in the peritoneum, time on dialysis and age. There was no association between the modality and the presence of diabetes, blood volume or nutritional status. Both modalities enable good adaptation to the dialysis treatment.

CONCLUSION

Inflammation in automated peritoneal dialysis is mainly associated with low residual renal function, advanced age and longer time on therapy, and not to the type of dialysis performed.

Clinical perspectives on the age-related increase of immunosuppressive activity

The aging process is associated with a remodeling of the immune system involving chronic low-grade inflammation and a gradual decline in the function of the immune system. These processes are also called inflammaging and immunosenescence. The age-related immune remodeling is associated with many clinical changes, e.g., risk for cancers and chronic infections increases, whereas the efficiency of vaccination and immunotherapy declines with aging. On the other hand, there is convincing evidence that chronic inflammatory states promote the premature aging process. The inflammation associated with aging or chronic inflammatory conditions stimulates a counteracting immunosuppression which protects tissues from excessive inflammatory injuries but promotes immunosenescence. Immunosuppression is a driving force in tumors and chronic infections and it also induces the tolerance to vaccination and immunotherapies. Immunosuppressive cells, e.g., myeloid-derived suppressor cells (MDSC), regulatory T cells (Treg), and type M2 macrophages, have a crucial role in tumorigenesis and chronic infections as well as in the tolerance to vaccination and immunotherapies. Interestingly, there is substantial evidence that inflammaging is also associated with an increased immunosuppressive activity, e.g., upregulation of immunosuppressive cells and anti-inflammatory cytokines. Given that both the aging and chronic inflammatory states involve the activation of immunosuppression and immunosenescence, this might explain why aging is a risk factor for tumorigenesis and chronic inflammatory states and conversely, chronic inflammatory insults promote the premature aging process in humans.

Stem Cell-Derived Extracellular Vesicles as Potential Therapeutic Approach for Acute Kidney Injury

Acute kidney injury is a frequent complication of hospitalized patients and significantly increases morbidity and mortality, worsening costs and length of hospital stay. Despite this impact on healthcare system, treatment still remains only supportive (dialysis). Stem cell-derived extracellular vesicles are a promising option as they recapitulate stem cells properties, overcoming safety issues related to risks or rejection or aberrant differentiation. A growing body of evidence based on pre-clinical studies suggests that extracellular vesicles may be effective to treat acute kidney injury and to limit fibrosis through direct interference with pathogenic mechanisms of vascular and tubular epithelial cell damage. We herein analyze the state-of-the-art knowledge of therapeutic approaches with stem cell-derived extracellular vesicles for different forms of acute kidney injury (toxic, ischemic or septic) dissecting their cytoprotective, regenerative and immunomodulatory properties. We also analyze the potential impact of extracellular vesicles on the mechanisms of transition from acute kidney injury to chronic kidney disease, with a focus on the pivotal role of the inhibition of complement cascade in this setting. Despite some technical limits, nowadays the development of therapies based on stem cell-derived extracellular vesicles holds promise as a new frontier to limit acute kidney injury onset and progression.

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.

Accelerated epigenetic aging and inflammatory/immunological profile (ipAGE) in patients with chronic kidney disease

Chronic kidney disease (CKD) is defined by a reduced estimated glomerular filtration rate (eGFR). This failure can be related to a phenotype of accelerated aging. In this work, we considered 76 patients with end-stage renal disease (ESRD) and 83 healthy controls. We concomitantly evaluated for the first time two measures that can be informative of the rate of aging, i.e., whole blood DNA methylation using the Illumina Infinium EPIC array and plasma levels of a selection of inflammatory/immunological proteins using multiplex immunoassays. First of all, we demonstrated accelerated aging in terms of the most common epigenetic age estimators in CKD patients. Moreover, we developed a new clock/predictor of age based on the inflammatory/immunological profile (ipAGE) and identified the inflammatory/immunological biomarkers differentially expressed between cases and controls. IpAGE appeared to be more sensitive than epigenetic clocks in quantifying the accelerated aging phenotype of ESRD patients. Interestingly, we did not find any correlation between the age acceleration evaluated according to the epigenetic clocks and ipAGE in either the ESRD group or the control group. On the whole, our data show a consistent accelerated aging phenotype in ESRD patients, which is better appreciated by quantifying the underlying inflammatory processes (inflammaging) by ipAGE than by using epigenetic clocks.

Inflammation and Cardiovascular Disease Associated With Hemodialysis for End-Stage Renal Disease

Chronic kidney disease (CKD) and cardiac insufficiency often co-exist, particularly in uremic patients on hemodialysis (HD). The occurrence of abnormal renal function in patients with cardiac insufficiency is often indicative of a poor prognosis. It has long been established that in patients with cardiac insufficiency, poorer renal function tends to indicate poorer cardiac mechanics, including left atrial reserve strain, left ventricular longitudinal strain, and right ventricular free wall strain (Unger et al., Eur J Heart Fail, 2016, 18(1), 103–12). Similarly, patients with chronic kidney disease, particularly uremic patients on HD, often have cardiovascular complications in addition to abnormal endothelial function with volume overload, persistent inflammatory states, calcium overload, and imbalances in redox responses. Cardiac insufficiency due to uremia is therefore mainly due to multifaceted non-specific pathological changes rather than pure renal insufficiency. Several studies have shown that the risk of adverse cardiovascular events is greatly increased and persistent in all patients treated with HD, especially in those who have just started HD treatment. Inflammation, as an important intersection between CKD and cardiovascular disease, is involved in the development of cardiovascular complications in patients with CKD and is indicative of prognosis (Chan et al., Eur Heart J, 2021, 42(13), 1244–1253). Therefore, only by understanding the mechanisms underlying the sequential development of inflammation in CKD patients and breaking the vicious circle between inflammation-mediated renal and cardiac insufficiency is it possible to improve the prognosis of patients with end-stage renal disease (ESRD). This review highlights the mechanisms of inflammation and the oxidative stress that co-exists with inflammation in uremic patients on dialysis, as well as the mechanisms of cardiovascular complications in the inflammatory state, and provides clinical recommendations for the anti-inflammatory treatment of cardiovascular complications in such patients.

Outcomes of Transcatheter Aortic Valve Implantation in Patients With Chronic and End-Stage Kidney Disease

Patients with chronic kidney disease (CKD) and end-stage kidney disease (ESKD) are at higher risk of aortic stenosis. Data regarding transcatheter aortic valve implantation (TAVI) in these patients are limited. Herein, we aim to investigate TAVI outcomes in patients with ESKD and CKD. We analyzed clinical data of patients with ESKD and CKD who underwent TAVI from 2008 to 2018 in a large urban healthcare system. Patients' demographics were compared, and significant morbidity and mortality outcomes were noted. Multivariable analyses were used to adjust for potential baseline variables. A total of 643 patients with CKD underwent TAVI with an overall in-hospital mortality of 5.1%, whereas 84 patients with ESKD underwent TAVI with an overall mortality rate of 11.9%. The most frequently observed comorbidities in patients with CKD were heart failure, atrial fibrillation (AF), mitral stenosis (MS), pulmonary hypertension, and chronic lung disease. After multivariable analysis, MS (adjusted odds ratio (OR) 3.92; 95% confidence interval (CI) 1.09 to 11.1, p <0.05) and AF (adjusted OR 2.42; 95% CI 1.3 to 4.4 p <0.05) were independently associated with mortality in patients with CKD. The most common comorbidities observed in patients with ESKD undergoing TAVI were heart failure, chronic lung disease, AF, MS, and pulmonary hypertension. An association between MS and increased mortality was observed (adjusted OR 2.01; 95 CI 0.93 to 2.02, p = 0.09) in patients with ESKD, but was not statistically significant. In conclusion, in patients with CKD undergoing TAVI, AF and MS were independently associated with increased mortality.

TLR13 contributes to skeletal muscle atrophy by increasing insulin resistance in chronic kidney disease

Objectives

Insulin resistance in chronic kidney disease (CKD) stimulates muscle wasting, but the molecular processes behind the resistance are undetermined. However, inflammation in skeletal muscle is implicated in the pathogenesis of insulin resistance and cachexia. Toll‐like receptors (TLRs) are known to regulate local innate immune responses, and microarray data have shown that Tlr13 is upregulated in the muscles of mice with CKD, but the relevance is unknown.

Materials and Methods

We performed in vitro experiments in C2C12 myotubes and constructed a CKD murine model using subtotal nephrectomy to conduct experiments in vivo.

Results

Tlr13 expression was stimulated in C2C12 myotubes treated with uremic serum. The expression of Tlr13 was also upregulated in the tibialis anterior muscles of mice with CKD. Tlr13 knockdown with siRNAs in skeletal muscle cells decreased insulin resistance despite the inclusion of uremic serum. This led to increased levels of p‐AKT and suppression of protein degradation. Using immunofluorescence staining and coimmunoprecipitation assay, we found that TLR13 recruits IRF3, which activates Irf3 expression, resulting in decreased AKT activity. Moreover, insulin resistance and proteolysis are re‐induced by Irf3 overexpression under Tlr13 deletion.

Conclusions

Our results indicate that TLR13 is involved in CKD‐mediated insulin resistance in muscle. In catabolic conditions where insulin signaling is impaired, targeting TLR13 may improve insulin sensitivity and prevent muscle atrophy.

Renoprotective Roles of Curcumin

The use of herb-based therapies is increasing over the past decades. These agents have been reported to provide many beneficial effects in many experimental and clinical studies. Curcumin is one of these agents which has potent pharmacological effects enabling it for the prevent and treatment of many diseases and pathologies such as renal disorders, hyperglycemia, oxidative stress, hypertension, and dyslipidemia. However, the exact molecular mechanisms mediating these renoprotective effects of curcumin are not well established. So, in the current study, we surveyed for possible renoprotective roles of curcumin and concluded how curcumin protects against renal injuries.

Fatigue and apathy in patients on chronic hemodialysis

INTRODUCTION

This study explores the link between fatigue and apathy in patients on chronic hemodialysis (HD).

METHODS

One hundred thirty-nine chronic HD patients underwent the assessment of fatigue, apathy, depression, and their functional status, with the fatigue severity scale (FSS), the Apathy Evaluation Scale (AES), the beck depression inventory (BDI), the activity of daily living (ADL), and instrumental activity of daily living (IADL).

RESULTS

Patients with high FSS had a significantly lower ADL and IADL score, higher BDI, Charlson Comorbidity Index, and AES score, and lower serum levels of creatinine, compared to low FSS patients. FSS was highly correlated with the AES, as well as with the BDI and the AES correlates with the BDI. At multiple regression analyses, only apathy and IADL were independent predictor variables of fatigue in HD population.

CONCLUSION

Future longitudinal studies could determine if apathy is a causative factor for fatigue manifestation and development in HD patients.

Chronic Kidney Disease and Arterial Stiffness: A Two-Way Path

The kidney-heart relationship has raised interest for the medical population since its vast and complex interaction significantly impacts health. Chronic kidney disease (CKD) generates vascular structure and function changes, with significant hemodynamic effects. The early arterial stiffening in CKD patients is a consequence of the interaction between oxidative stress and chronic vascular inflammation, leading to an accelerated deterioration of left ventricular function and alteration in tissue perfusion. CKD amplifies the inflammatory cascade's activation and is responsible for altering the endothelium function, increasing the vascular tone, wall thickening, and favors calcium deposits in the arterial wall. Simultaneously, the autonomic imbalance, and alteration in other hormonal systems, also favor the overactivation of inflammatory and fibrotic mediators. Thus, hormonal disarrangement also contributes to structural and functional lesions throughout the arterial wall. On the other hand, a rise in arterial stiffening and volume overload generates high left ventricular afterload. It increases the left ventricular burden with consequent myocardial remodeling, development of left ventricular hypertrophy and, in turn, heart failure. It is noteworthy that reduction in glomerular mass of renal diseases generates a compensatory glomerular filtration overdriven associated with large-arteries stiffness and high cardiovascular events. Furthermore, we consider that the consequent alterations of the arterial system's mechanical properties are crucial for altering tissue perfusion, mainly in low resistance. Thus, increasing the knowledge of these processes may help the reader to integrate them from a pathophysiological perspective, providing a comprehensive idea of this two-way path between arterial stiffness and renal dysfunction and their impact at the cardiovascular level.

Inflammation and Oxidative Stress in Chronic Kidney Disease and Dialysis Patients

Significance: Chronic kidney disease (CKD) can be regarded as a burden of lifestyle disease that shares common underpinning features and risk factors with the aging process; it is a complex constituted by several adverse components, including chronic inflammation, oxidative stress, early vascular aging, and cellular senescence. Recent Advances: A systemic approach to tackle CKD, based on mitigating the associated inflammatory, cell stress, and damage processes, has the potential to attenuate the effects of CKD, but it also preempts the development and progression of associated morbidities. In effect, this will enhance health span and compress the period of morbidity. Pharmacological, nutritional, and potentially lifestyle-based interventions are promising therapeutic avenues to achieve such a goal. Critical Issues: In the present review, currents concepts of inflammation and oxidative damage as key patho-mechanisms in CKD are addressed. In particular, potential beneficial but also adverse effects of different systemic interventions in patients with CKD are discussed. Future Directions: Senotherapeutics, the nuclear factor erythroid 2-related factor 2-kelch-like ECH-associated protein 1 (NRF2-KEAP1) signaling pathway, the endocrine klotho axis, inhibitors of the sodium-glucose cotransporter 2 (SGLT2), and live bio-therapeutics have the potential to reduce the burden of CKD and improve quality of life, as well as morbidity and mortality, in this fragile high-risk patient group. Antioxid. Redox Signal. 35, 1426-1448.