Soluble Tumor Necrosis Factor Receptor 1 Is Associated with Glomerular Filtration Rate Progression and Incidence of Chronic Kidney Disease in Two Community-Based Cohorts of Elderly Individuals

Assessment and Risk Prediction of Chronic Kidney Disease and Kidney Fibrosis Using Non-Invasive Biomarkers

Effective management of chronic kidney disease (CKD), a major health problem worldwide, requires accurate and timely diagnosis, prognosis of progression, assessment of therapeutic efficacy, and, ideally, prediction of drug response. Multiple biomarkers and algorithms for evaluating specific aspects of CKD have been proposed in the literature, many of which are based on a small number of samples. Based on the evidence presented in relevant studies, a comprehensive overview of the different biomarkers applicable for clinical implementation is lacking. This review aims to compile information on the non-invasive diagnostic, prognostic, and predictive biomarkers currently available for the management of CKD and provide guidance on the application of these biomarkers. We specifically focus on biomarkers that have demonstrated added value in prospective studies or those based on prospectively collected samples including at least 100 subjects. Published data demonstrate that several valid non-invasive biomarkers of potential value in the management of CKD are currently available.

Renal Papillary Necrosis (RPN) in an African Population: Disease Patterns, Relevant Pathways, and Management

Renal papillary necrosis (RPN) is characterized by coagulative necrosis of the renal medullary pyramids and papillae. Multiple conditions and toxins are associated with RPN. Several RPN risk factors, or POSTCARDS, have been identified, with most patients presenting with RPN having at least two contributing risk factors. Currently, there is no specific test to diagnose and confirm RPN; however, several imaging tools can be used to diagnose the condition. RPN is currently underdiagnosed in African populations, often with fatal outcomes. In African clinical settings, there is a lack of consensus on how to define and describe RPN in terms of kidney anatomy, pathology, endourology, epidemiology, the identification of African-specific risk factors, the contribution of oxidative stress, and lastly an algorithm for managing the condition. Several risk factors are unique to African populations including population-specific genetic factors, iatrogenic factors, viral infections, antimicrobial therapy, schistosomiasis, substance abuse, and hypertension (GIVASSH). Oxidative stress is central to both GIVASSH and POSTCARDS-associated risk factors. In this review, we present information specific to African populations that can be used to establish an updated consensual definition and practical grading system for radiologists, urologists, nephrologists, nuclear physicians, and pathologists in African clinical settings.

Development of a Biomarker Panel to Distinguish Risk of Progressive Chronic Kidney Disease

Chronic kidney disease (CKD) patients typically progress to kidney failure, but the rate of progression differs per patient or may not occur at all. Current CKD screening methods are sub-optimal at predicting progressive kidney function decline. This investigation develops a model for predicting progressive CKD based on a panel of biomarkers representing the pathophysiological processes of CKD, kidney function, and common CKD comorbidities. Two patient cohorts are utilised: The CKD Queensland Registry (n = 418), termed the Biomarker Discovery cohort; and the CKD Biobank (n = 62), termed the Predictive Model cohort. Progression status is assigned with a composite outcome of a ≥30% decline in eGFR from baseline, initiation of dialysis, or kidney transplantation. Baseline biomarker measurements are compared between progressive and non-progressive patients via logistic regression. In the Biomarker Discovery cohort, 13 biomarkers differed significantly between progressive and non-progressive patients, while 10 differed in the Predictive Model cohort. From this, a predictive model, based on a biomarker panel of serum creatinine, osteopontin, tryptase, urea, and eGFR, was calculated via linear discriminant analysis. This model has an accuracy of 84.3% when predicting future progressive CKD at baseline, greater than eGFR (66.1%), sCr (67.7%), albuminuria (53.2%), or albumin-creatinine ratio (53.2%).

Acute kidney injury risk in orthopaedic trauma patients pre and post surgery using a biomarker algorithm and clinical risk score

Acute kidney injury (AKI) after major trauma is associated with increased mortality. The aim of this study was to assess if measurement of blood biomarkers in combination with clinical characteristics could be used to develop a tool to assist clinicians in identifying which orthopaedic trauma patients are at risk of AKI. This is a prospective study of 237 orthopaedic trauma patients who were consecutively scheduled for open reduction and internal fixation of their fracture between May 2012 and August 2013. Clinical characteristics were recorded, and 28 biomarkers were analysed in patient blood samples. Post operatively a combination of H-FABP, sTNFR1 and MK had the highest predictive ability to identify patients at risk of developing AKI (AUROC 0.885). Three clinical characteristics; age, dementia and hypertension were identified in the orthopaedic trauma patients as potential risks for the development of AKI. Combining biomarker data with clinical characteristics allowed us to develop a proactive AKI clinical tool, which grouped patients into four risk categories that were associated with a clinical management regime that impacted patient care, management, length of hospital stay, and efficient use of hospital resources.

TNFR1 is associated with short-term mortality in patients with diabetes and acute dyspnea seeking care at the emergency department

BACKGROUND

Circulating levels of TNF alpha receptor 1 (TNFR1) and 2 (TNFR2) are associated with increased long-term mortality and impaired kidney function.

AIM

To study association between circulating levels of TNFR1 and TNFR2 and short-term mortality in patients with diabetes and dyspnea.

POPULATION AND METHODS

Patients aged ≥ 18 years seeking at emergency department (ED) during daytime on weekdays between December 2013 and July 2018, with diabetes and acute dyspnea, identified at the triage process, were included. Participants (n = 291) were triaged according to Medical Emergency Triage and Treatment System-Adult score, and blood samples were collected. Association between TNFR1 and TNFR2, respectively, and 90-day mortality were estimated by Cox regression models adjusted for age, sex, BMI, creatinine and CRP.

RESULTS

Univariate models showed significant associations between TNFR1 and TNFR2, respectively, and CRP, age and creatinine. TNFR1 and TNFR2 tended to be elevated in patients with the highest triage level, compared to patients with lower triage levels (ns). In longitudinal analyses, TNFR1 but not TNFR2 was associated with increased short-term mortality, HR adjusted for age, BMI and creatinine 1.43 (95% CI 1.07-1.91), but not in the model also adjusted for CRP, HR 1.29 (95% CI 0.94-1.77). In secondary analysis for quartile 4 versus quartiles 1-3 of TNFR1, corresponding HRs were 2.46 (95% CI 1.27-5.15) and 2.21 (95% CI 1.07-2.56).

CONCLUSIONS

We found a trend for the association between circulating TNFR1 levels and short-term mortality in patients with diabetes and acute dyspnea at the ED, possibly suggesting an inflammatory pathway for the association.

Association between circulating tumor necrosis factor receptors and oral bacterium in patients receiving hemodialysis: a cross-sectional study

BACKGROUND

High levels of tumor necrosis factor (TNF) receptors (TNFRs; TNFR1 and TNFR2), markers of inflammation, have been reported as significant predictors of mortality in hemodialysis patients. Porphyromonas gingivalis is a major pathogenic bacterium involved in periodontitis, which induces systemic inflammation. We investigated the association between the abundance of P. gingivalis in saliva and serum TNFR levels in hemodialysis patients.

METHODS

A cross-sectional study was conducted on 121 hemodialysis patients visiting a clinic in the Tokyo metropolitan area. Medical interviews and examinations, comprehensive dental examinations, bacterial examinations for P. gingivalis in saliva, and measurements of circulating TNFR levels were conducted. Multiple linear regression analysis was performed to evaluate the association between the number of P. gingivalis and circulating TNFR levels.

RESULTS

TNFR1 and TNFR2 were positively correlated with high-sensitivity C-reactive protein (hsCRP). Severe periodontitis was significantly associated with the number of P. gingivalis in saliva but not serum TNFR levels. The number of P. gingivalis was significantly associated with both TNFR1 and TNFR2 levels in sera after adjusting for age, sex, body mass index, smoking status, history of diabetes, prior cardiovascular disease events, serum levels of hsCRP and albumin, and severity of periodontitis [for TNFR1: coefficient 0.76, 95% confidence interval (CI) 0.14-1.37, p = 0.02; for TNFR2: coefficient 0.95, 95% CI 0.09-1.80, p = 0.03].

CONCLUSION

Circulating TNFR levels are associated with the number of P. gingivalis in saliva after adjusting for relevant clinical factors.

Initial Validation of a Machine Learning-Derived Prognostic Test (KidneyIntelX) Integrating Biomarkers and Electronic Health Record Data To Predict Longitudinal Kidney Outcomes

Background

Individuals with type 2 diabetes (T2D) or the apolipoprotein L1 high-risk (APOL1-HR) genotypes are at increased risk of rapid kidney function decline (RKFD) and kidney failure. We hypothesized that a prognostic test using machine learning integrating blood biomarkers and longitudinal electronic health record (EHR) data would improve risk stratification.

Methods

We selected two cohorts from the Mount Sinai BioMe Biobank: T2D (n=871) and African ancestry with APOL1-HR (n=498). We measured plasma tumor necrosis factor receptors (TNFR) 1 and 2 and kidney injury molecule-1 (KIM-1) and used random forest algorithms to integrate biomarker and EHR data to generate a risk score for a composite outcome: RKFD (eGFR decline of ≥5 ml/min per year), or 40% sustained eGFR decline, or kidney failure. We compared performance to a validated clinical model and applied thresholds to assess the utility of the prognostic test (KidneyIntelX) to accurately stratify patients into risk categories.

Results

Overall, 23% of those with T2D and 18% of those with APOL1-HR experienced the composite kidney end point over a median follow-up of 4.6 and 5.9 years, respectively. The area under the receiver operator characteristic curve (AUC) of KidneyIntelX was 0.77 (95% CI, 0.75 to 0.79) in T2D, and 0.80 (95% CI, 0.77 to 0.83) in APOL1-HR, outperforming the clinical models (AUC, 0.66 [95% CI, 0.65 to 0.67] and 0.72 [95% CI, 0.71 to 0.73], respectively; P<0.001). The positive predictive values for KidneyIntelX were 62% and 62% versus 46% and 39% for the clinical models (P<0.01) in high-risk (top 15%) stratum for T2D and APOL1-HR, respectively. The negative predictive values for KidneyIntelX were 92% in T2D and 96% for APOL1-HR versus 85% and 93% for the clinical model, respectively (P=0.76 and 0.93, respectively), in low-risk stratum (bottom 50%).

Conclusions

In patients with T2D or APOL1-HR, a prognostic test (KidneyIntelX) integrating biomarker levels with longitudinal EHR data significantly improved prediction of a composite kidney end point of RKFD, 40% decline in eGFR, or kidney failure over validated clinical models.

Circulating TNF receptors and risk of renal disease progression, cardiovascular disease events and mortality in patients with diabetes: a systematic review and meta-analysis

PURPOSE

Inflammation plays an important role in the pathogenesis of diabetes complications. This study aims to assess the association between circulating inflammatory biomarkers TNF receptors (TNFRs) and the risk of renal disease progression, cardiovascular disease (CVD) events, and mortality in patients with diabetes.

METHODS

PubMed and Embase databases were comprehensively searched up to March 2019. Data were extracted independently by two reviewers. A random effects model was performed for the pooled analyses.

RESULTS

Five studies in 3316 subjects assessed TNFRs with renal disease in patients with type 1 diabetes and showed both TNFR-1 and TNFR-2 were consistently associated with the renal outcomes. Fourteen studies in 7696 subjects evaluated TNFRs in patients with type 2 diabetes. The pooled risk ratio per doubling increase in TNFR-1 and TNFR-2 for renal disease progression was more than two (2.64 [1.98, 3.52] and 2.23 [1.69, 2.94]). The subgroup analyses and sensitivity analyses further illustrated these results of renal outcome and its robustness. Moreover, higher TNFR-1 and TNFR-2 was also significantly associated with CVD events and mortality in patients with type 2 diabetes.

CONCLUSIONS

Circulating TNFR-1 and TNFR-2 are independently associated with higher risk of renal disease progression, CVD events, and mortality in patients with diabetes and might contribute to the clinical risk assessment in the future.

Found in Translation: Reasons for Optimism in the Pursuit to Prevent Chronic Kidney Disease After Acute Kidney Injury

Purpose of review:

The current review will discuss on the progress of studying the transition phase between acute kidney injury (AKI) and chronic kidney disease (CKD) through improved animal models, common AKI and CKD pathways, and how human studies may inform different translational approaches.

Sources of information:

PubMed and Google Scholar.

Methods:

A narrative review was performed using the main terms “acute kidney injury,” “chronic kidney disease,” “end-stage renal disease,” “animal models,” “review,” “decision-making,” and “translational research.”

Key findings:

The last decade has shown much progress in the study of AKI, including evidence of a pathophysiological link between AKI and CKD. We are now in a phase of redesigning animal models and discovering mechanisms that can replicate the pathological conditions of the AKI-to-CKD continuum. Translating these findings into the clinic is a barrier that must be overcome. To this end, current efforts include prediction of AKI onset and maladaptive repair, detecting patients susceptible to the progression of chronic maladaptive repair, and understanding shared signaling mechanisms between AKI and CKD.

Limitations:

This is a narrative review of the literature that is partially influenced by the knowledge, perspectives, and experiences of the authors and their research background.

Implications:

Overall, this new knowledge from the AKI-to-CKD continuum will help bridge the discontinuity that exists between animal models and patients, resulting in more effective translational biomarkers and therapeutics to test in known AKI pathologies thereby preventing the chronicity of kidney injury progression.

Serum cystatin C, impaired kidney function, and geriatric depressive symptoms among older people living in a rural area: a population-based study

BACKGROUND

The relationship between kidney function and depressive symptoms among elderly people has been rarely investigated in settings of the general population. The aim of our study was to examine the association of serum cystatin C (cysC) and impaired kidney function with geriatric depressive symptoms among older people living in a rural community in China.

METHODS

This population-based cohort study included 1440 individuals (age ≥ 60 years) who were recruited for the Confucius Hometown Aging Project in 2010-2011; of the 1124 persons who were free of depressive symptoms, 669 (59.5%) were re-examined in 2014-2016. At baseline, data on demographics, lifestyle factors, health conditions, and medical history were collected through interviews, clinical examinations, and laboratory tests. We defined impaired kidney function as the cystatin C-based estimated glomerular filtration rate (eGFR_cysC) < 60 ml/min/1.73 m², and depressive symptoms as a score ≥ 5 on the 15-item Geriatric Depression Scale. Data were analyzed using multiple logistic and Cox proportional-hazards models.

RESULTS

Of the 1440 participants, 316 (21.9%) were defined to have geriatric depressive symptoms at baseline. Serum cysC levels of 1.01-1.25 and > 1.25 mg/L (vs. ≤1.00 mg/L) were associated with a multiple-adjusted odds ratio (OR) of 1.41 (95% CI 1.01-1.97) and 3.20 (2.32-4.41), respectively, for having geriatric depressive symptoms (P_trend < 0.001). Of the 669 people who were free of depressive symptoms at baseline, 157 had incident depressive symptoms at the follow-up examination. The multiple-adjusted hazard ratio (HR) for incident depressive symptoms were 2.16 (95% CI 1.43-3.27) for serum cysC > 1.25 mg/L (vs. < 1.00 mg/L). Impaired kidney function was cross-sectionally (multiple-adjusted OR = 2.95; 95% CI 2.22-3.92) and longitudinally (multiple-adjusted HR 1.54; 95% CI 1.03-2.30) associated with an increased risk of geriatric depressive symptoms.

CONCLUSION

Elevated serum cysC levels and impaired kidney function are associated with an increased risk of geriatric depressive symptoms among Chinese older people living in a rural community.

Plasma biomarkers are associated with renal outcomes in individuals with APOL1 risk variants

G1/G2 variants in the Apolipoprotein L1 (APOL1) gene are associated with end-stage renal disease (ESRD) in people with African ancestry. Plasma biomarkers may have utility for risk stratification in APOL1 high-risk individuals of African ancestry. To evaluate this, we measured tumor necrosis factor receptor 1/2 (TNFR1/2) and kidney injury molecule-1 (KIM1) in baseline plasma specimens from individuals of African ancestry with high-risk APOL1 genotype. Biomarker association with a composite renal outcome of ESRD or 40% sustained decline in estimated glomerular filtration rate (eGFR) was then determined and then assessed as improvement in area under curve. Among the 498 participants, the median age was 56 years, 67.7% were female, and the baseline eGFR was 83.3 ml/min/1.73 m2 with 80 reaching outcome over 5.9 years. TNFR1, TNFR2, and KIM1 at enrollment were independently associated with renal outcome continuously (adjusted hazard ratio 2.0 [95% confidence interval 1.3-3.1]; 1.5 [1.2-1.9]; and 1.6 [1.3-1.9] per doubling in levels, respectively) or by tertiles. The area under the curve significantly improved from 0.75 with the clinical model to 0.79 with the biomarker-enhanced model. The event rate was 40% with all 3 biomarkers elevated (adjusted odds ratio of 5.3 (2.3-12.0) vs. 17% (adjusted odds ratio 1.8 [0.9-3.6] with 1 or 2 elevated and 7% with no biomarkers elevated. Thus, plasma concentrations of TNFR1, TNFR2, and KIM1 are independently associated with renal outcome and improve discrimination or reclassification of African ancestry individuals with a high-risk APOL1 genotype and preserve renal function. Elevation of all markers had higher risk of outcome and can assist with better clinical prediction and improved clinical trial efficiency by enriching event rates.

10-Year Associations Between Tumor Necrosis Factor Receptors 1 and 2 and Cardiovascular Events in Patients With Stable Coronary Heart Disease: A CLARICOR (Effect of Clarithromycin on Mortality and Morbidity in Patients With Ischemic Heart Disease) Trial Substudy

BACKGROUND

We aimed to assess the associations and predictive powers between the soluble receptors for tumor necrosis factor (TNF)-α (TNFR1 and TNFR2) and cardiovascular outcomes in patients with stable coronary heart disease.

METHODS AND RESULTS

CLARICOR (Effect of Clarithromycin on Mortality and Morbidity in Patients With Ischemic Heart Disease) is a randomized clinical trial comparing clarithromycin with placebo in patients with stable coronary heart disease. The primary outcome was a composite of nonfatal acute myocardial infarction, unstable angina pectoris, cerebrovascular disease, and all-cause mortality. Patients were followed up for 10 years; discovery sample, those assigned placebo (1204 events in n=1998); and replication sample, those assigned clarithromycin (1220 events in n=1979). We used Cox regression adjusted for C-reactive protein level, established cardiovascular risk factors, kidney function, and cardiovascular drugs. After adjustments, higher serum levels of TNFR1 and TNFR2 were associated with the composite outcome in the discovery sample (hazard ratio per SD increase, 1.13; 95% confidence interval, 1.05-1.22; P=0.001 for TNFR1; hazard ratio, 1.16; 95% confidence interval, 1.08-1.24; P<0.001 for TNFR2). The associations were similar in the replication sample. The associations with the composite outcome were mainly driven by acute myocardial infarction, cardiovascular mortality, and noncardiovascular mortality. The addition of TNFR1 and TNFR2 to established cardiovascular risk factors improved prediction only modestly (<1%).

CONCLUSIONS

Increased concentrations of circulating TNFR1 and TNFR2 were associated with increased risks of cardiovascular events and mortality in patients with stable coronary heart disease. Yet, the utility of measuring TNFR1 and TNFR2 to improve risk prediction in these patients appears limited.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00121550.

High Baseline Levels of Tumor Necrosis Factor Receptor 1 Are Associated With Progression of Kidney Disease in Indigenous Australians With Diabetes: The eGFR Follow-up Study

OBJECTIVE

To examine the association between soluble tumor necrosis factor receptor 1 (sTNFR1) levels and kidney disease progression in Indigenous Australians at high risk of kidney disease.

RESEARCH DESIGN AND METHODS

This longitudinal observational study examined participants aged ≥18 years recruited from >20 sites across diabetes and/or kidney function strata. Baseline measures included sTNFR1, serum creatinine, urine albumin-to-creatinine ratio (uACR), HbA_1c, C-reactive protein (CRP), waist-to-hip ratio, systolic blood pressure, and medical history. Linear regression was used to estimate annual change in estimated glomerular filtration rate (eGFR) for increasing sTNFR1, and Cox proportional hazards were used to estimate the hazard ratio (HR) and 95% CI for developing a combined renal outcome (first of a ≥30% decline in eGFR with a follow-up eGFR <60 mL/min/1.73 m², progression to renal replacement therapy, or renal death) for increasing sTNFR1.

RESULTS

Over a median of 3 years, participants with diabetes (n = 194) in the highest compared with the lowest quartile of sTNFR1 experienced significantly greater eGFR decline (-4.22 mL/min/1.73 m²/year [95% CI -7.06 to -1.38]; P = 0.004), independent of baseline age, sex, eGFR, and uACR. The adjusted HR (95% CI) for participants with diabetes per doubling of sTNFR1 for the combined renal outcome (n = 32) was 3.8 (1.1-12.8; P = 0.03). No association between sTNFR1 and either renal outcome was observed for those without diabetes (n = 259).

CONCLUSIONS

sTNFR1 is associated with greater kidney disease progression independent of albuminuria and eGFR in Indigenous Australians with diabetes. Further research is required to assess whether TNFR1 operates independently of other metabolic factors associated with kidney disease progression.

Inflammation and Trajectory of Renal Function in Community-Dwelling Older Adults

OBJECTIVES

To examine the hypothesis that the inflammatory state of aging is a risk factor for accelerated renal function (RF) decline using inflammatory biomarkers and RF measures collected over 9 years of follow-up in relatively healthy individuals enrolled in the Invecchiare in Chianti study.

DESIGN

Longitudinal.

SETTING

Community.

PARTICIPANTS

Individuals aged 60 and older with baseline estimated glomerular filtration rate (eGFR) of 60 mL/min per 1.73 m² and greater and no diabetes mellitus (DM) (N = 687).

MEASURES

eGFR, as a proxy for RF, was determined using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation at baseline and 3-, 6-, and 9-year follow-up. Incident chronic kidney disease (CKD) was defined as new-onset eGFR less than 60 mL/min per 1.73 m² at each follow-up. Predictors included baseline and time-dependent inflammatory biomarkers: soluble tumor necrosis factor alpha receptors (sTNFα-R1 and -R2), interleukin (IL)-6, IL-18, IL-1β, IL-1 receptor antagonist, and high-sensitivity C-reactive protein.

RESULTS

Higher baseline sTNFα-R1 was significantly associated with lower eGFR over 9 years, independent of DM or blood pressure (baseline: β^ = -0.39, P = .001; 3-year: β^ = -0.26, P = .001; 6-year: β^ = -0.36, P = .001; 9-year: β^ = -0.47, P = .001). The rate of TNFα-R1 change was significantly associated with rate of eGFR change (β^ = -0.18, P = .001). Baseline sTNFα-R1 predicted incident CKD (per 1-standard deviation increment: 3-year: relative risk (RR) = 1.3, 95% confidence interval (CI) = 1.1-1.5; 6-year: RR = 1.5, 95% CI = 1.1-2.2; 9-year RR = 1.6, 95% CI = 1.1-2.2). Similar results were found for sTNFα-R2.

CONCLUSION

Baseline TNFα-R levels and their rates of change were significantly associated with RF decline and incident CKD in older adults independent of DM or blood pressure.

Association of TNF Receptor 2 and CRP with GFR Decline in the General Nondiabetic Population

BACKGROUND AND OBJECTIVES

Higher levels of inflammatory markers have been associated with renal outcomes in diabetic populations. We investigated whether soluble TNF receptor 2 (TNFR2) and high-sensitivity C-reactive protein (hsCRP) were associated with the age-related GFR decline in a nondiabetic population using measured GFR (mGFR).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A representative sample of 1590 middle-aged people from the general population without prevalent kidney disease, diabetes, or cardiovascular disease were enrolled in the Renal Iohexol-Clearance Survey in Tromsø 6 (RENIS-T6) between 2007 and 2009. After a median of 5.6 years, 1296 persons were included in the Renal Iohexol-Clearance Survey Follow-Up Study. GFR was measured using iohexol clearance at baseline and follow-up.

RESULTS

The mean decline of mGFR during the period was -0.84 ml/min per 1.73 m2 per year. There were 133 participants with rapid mGFR decline, defined as an annual mGFR loss >3.0 ml/min per 1.73 m2, and 26 participants with incident CKD, defined as mGFR<60 ml/min per 1.73 m2 at follow-up. In multivariable adjusted mixed models, 1 mg/L higher levels of hsCRP were associated with an accelerated decline in mGFR of -0.03 ml/min per 1.73 m2 per year (95% confidence interval [95% CI], -0.05 to -0.01), and 1 SD higher TNFR2 was associated with a slower decline in mGFR (0.09 ml/min per 1.73 m2 per year; 95% CI, 0.01 to 0.18). In logistic regression models adjusted for sex, age, weight, and height, 1 mg/L higher levels of hsCRP were associated with higher risk of rapid mGFR decline (odds ratio, 1.03; 95% CI, 1.01 to 1.06) and incident CKD (odds ratio, 1.04; 95% CI, 1.00 to 1.08).

CONCLUSIONS

Higher baseline levels of hsCRP but not TNFR2 were associated with accelerated age-related mGFR decline and incident CKD in a general nondiabetic population.

Inflammatory Cytokines as Uremic Toxins: "Ni Son Todos Los Que Estan, Ni Estan Todos Los Que Son"

Chronic kidney disease is among the fastest growing causes of death worldwide. An increased risk of all-cause and cardiovascular death is thought to depend on the accumulation of uremic toxins when glomerular filtration rate falls. In addition, the circulating levels of several markers of inflammation predict mortality in patients with chronic kidney disease. Indeed, a number of cytokines are listed in databases of uremic toxins and uremic retention solutes. They include inflammatory cytokines (IL-1β, IL-18, IL-6, TNFα), chemokines (IL-8), and adipokines (adiponectin, leptin and resistin), as well as anti-inflammatory cytokines (IL-10). We now critically review the cytokines that may be considered uremic toxins. We discuss the rationale to consider them uremic toxins (mechanisms underlying the increased serum levels and evidence supporting their contribution to CKD manifestations), identify gaps in knowledge, discuss potential therapeutic implications to be tested in clinical trials in order to make this knowledge useful for the practicing physician, and identify additional cytokines, cytokine receptors and chemokines that may fulfill the criteria to be considered uremic toxins, such as sIL-6R, sTNFR1, sTNFR2, IL-2, CXCL12, CX3CL1 and others. In addition, we suggest that IL-10, leptin, adiponectin and resistin should not be considered uremic toxins toxins based on insufficient or contradictory evidence of an association with adverse outcomes in humans or preclinical data not consistent with a causal association.

Circulating TNF Receptors 1 and 2 Predict Mortality in Patients with End-stage Renal Disease Undergoing Dialysis

Relatively high circulating levels of soluble tumor necrosis factor (TNF) receptors (TNFRs: TNFR1, TNFR2) have been associated with not only progression to end-stage renal disease but also mortality in patients with diabetes. It remains unknown whether elevated TNFR levels in haemodialysis patients are associated with mortality. We studied 319 patients receiving maintenance haemodialysis who were followed for a median of 53 months. Circulating markers of TNF pathway (TNFα and TNFRs) were measured with immunoassay. Strong positive correlations between TNFR1 and TNFR2 were observed (r = 0.81, P < 0.0001). During follow-up, 88 (27.6%) patients died of any cause (40 [45.5%] died of cardiovascular disease). In the Cox multivariate model, either TNFR but not TNFα remained a significant independent predictor of all-cause mortality (TNFR1: hazard ratio [HR] 2.34, 95% confidence interval [CI], 1.50–3.64; TNFR2: HR 2.13, 95% CI 1.38–3.29) after adjustment for age, prior cardiovascular disease, predialysis systolic blood pressure, and large systolic blood pressure decline during dialysis session. For cardiovascular mortality, significance was only observed in TNFR1 (TNFR1: HR 2.15, 95% CI 1.13–4.10). Elevated TNFRs levels were associated with the risk of cardiovascular and/or all-cause mortality independent of all relevant covariates in patients undergoing haemodialysis.

Correlation of higher levels of soluble TNF-R1 with a shorter survival, independent of age, in recurrent glioblastoma

The circulating levels of soluble tumor necrosis factor receptor-1 (sTNF-R1) and sTNF-R2 are altered in numerous diseases, including several types of cancer. Correlations with the risk of progression in some cancers, as well as systemic manifestations of the disease and therapeutic side-effects, have been described. However, there is very little information on the levels of these soluble receptors in glioblastoma (GBM). Here, we report on an exploratory retrospective study of the levels of sTNF-Rs in the vascular circulation of patients with GBM. Banked samples were obtained from 112 GBM patients (66 untreated, newly-diagnosed patients and 46 with recurrent disease) from two institutions. The levels of sTNF-R1 in the plasma were significantly lower in patients with newly-diagnosed or recurrent GBM than apparently healthy individuals and correlated with the intensity of expression of TNF-R1 on the tumor-associated endothelial cells (ECs) in the corresponding biopsies. Elevated levels of sTNF-R1 in patients with recurrent, but not newly-diagnosed GBM, were significantly associated with a shorter survival, independent of age (p = 0.02) or steroid medication. In contrast, the levels of circulating sTNF-R2 were significantly higher in recurrent GBM than healthy individuals and there was no significant correlation with expression of TNF-R2 on the tumor-associated ECs or survival time. The results indicate that larger, prospective studies are warranted to determine the predictive value of the levels of sTNF-R1 in patients with recurrent GBM and the factors that regulate the levels of sTNF-Rs in the circulation in GBM patients.

Inflammation and Progression of CKD: The CRIC Study

BACKGROUND AND OBJECTIVES

CKD is a global public health problem with significant mortality and morbidity.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined the multivariable association of plasma levels of IL-1, IL-1 receptor antagonist, IL-6, TNF-α, TGF-β, high-sensitivity C-reactive protein, fibrinogen, and serum albumin with progression of CKD in 3430 Chronic Renal Insufficiency Cohort study participants.

RESULTS

Over a median follow-up time of 6.3 years, 899 participants reached the composite end point of ≥50% decline in eGFR from baseline or onset of ESRD. Elevated plasma levels of fibrinogen, IL-6, and TNF-α and lower serum albumin were associated with a greater decline in eGFR over time. After adjusting for demographics, BP, laboratory variables, medication use, and baseline eGFR, hazard ratios for the composite outcome were greater for the patients in the highest quartile of fibrinogen (hazard ratio, 2.05; 95% confidence interval, 1.64 to 2.55; P<0.001), IL-6 (hazard ratio, 1.44; 95% confidence interval, 1.17 to 1.77; P<0.01), and TNF-α (hazard ratio, 1.94; 95% confidence interval, 1.52 to 2.47; P<0.001) compared with those in the respective lowest quartiles. The hazard ratio was 3.48 (95% confidence interval, 2.88 to 4.21; P<0.001) for patients in the lowest serum albumin quartile relative to those in the highest quartile. When also adjusted for albuminuria, the associations of fibrinogen (hazard ratio, 1.49; 95% confidence interval, 1.20 to 1.86; P<0.001), serum albumin (hazard ratio, 1.52; 95% confidence interval, 1.24 to 1.87; P<0.001), and TNF-α (hazard ratio, 1.42; 95% confidence interval, 1.11 to 1.81; P<0.001) with outcome were attenuated but remained significant.

CONCLUSIONS

Elevated plasma levels of fibrinogen and TNF-α and decreased serum albumin are associated with rapid loss of kidney function in patients with CKD.