Serum C-reactive protein and leptin as predictors of kidney disease progression in the Modification of Diet in Renal Disease Study

Cardiovascular complications in chronic kidney disease: a review from the European Renal and Cardiovascular Medicine Working Group of the European Renal Association

Chronic kidney disease (CKD) is classified into five stages with kidney failure being the most severe stage (stage G5). CKD conveys a high risk for coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. Cardiovascular complications are the most common causes of death in patients with kidney failure (stage G5) who are maintained on regular dialysis treatment. Because of the high death rate attributable to cardiovascular (CV) disease, most patients with progressive CKD die before reaching kidney failure. Classical risk factors implicated in CV disease are involved in the early stages of CKD. In intermediate and late stages, non-traditional risk factors, including iso-osmotic and non-osmotic sodium retention, volume expansion, anaemia, inflammation, malnutrition, sympathetic overactivity, mineral bone disorders, accumulation of a class of endogenous compounds called 'uremic toxins', and a variety of hormonal disorders are the main factors that accelerate the progression of CV disease in these patients. Arterial disease in CKD patients is characterized by an almost unique propensity to calcification and vascular stiffness. Left ventricular hypertrophy, a major risk factor for heart failure, occurs early in CKD and reaches a prevalence of 70-80% in patients with kidney failure. Recent clinical trials have shown the potential benefits of hypoxia-inducible factor prolyl hydroxylase inhibitors, especially as an oral agent in CKD patients. Likewise, the value of proactively administered intravenous iron for safely treating anaemia in dialysis patients has been shown. Sodium/glucose cotransporter-2 inhibitors are now fully emerged as a class of drugs that substantially reduces the risk for CV complications in patients who are already being treated with adequate doses of inhibitors of the renin-angiotensin system. Concerted efforts are being made by major scientific societies to advance basic and clinical research on CV disease in patients with CKD, a research area that remains insufficiently explored.

Association of rheumatoid arthritis with mortality in chronic kidney disease: a cohort study

BACKGROUND

Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD) as well as with an increased risk of chronic kidney disease (CKD), also a known cardiovascular risk factor. However, it is not known if RA is a predictor of adverse outcomes in patients with CKD. We hypothesized that among a cohort of patients with CKD, RA would be associated with an increased risk of mortality.

MATERIALS AND METHODS

We conducted a retrospective study of 3939 participants with CKD from the prospective Chronic Renal Insufficiency Cohort (CRIC) study. The primary outcome of interest was all-cause mortality. Secondary outcomes included CKD progression (defined as end-stage kidney disease or 50% decline in estimated glomerular filtration rate), cardiovascular endpoints, and composite of myocardial infarction, cerebrovascular accident, heart failure, or death. Multivariable Cox proportional hazards regression was utilized, adjusting for potential confounders including age, sex, race/ethnicity, body mass index, current smoker, and education.

RESULTS

The study cohort included 83 participants with RA on a disease modifying anti-rheumatic drug (DMARD). In the adjusted analysis, CKD-RA status was significantly associated with an increased risk of death (adjusted HR, aHR, 1.73 (1.27, 2.35)) and composite outcome (aHR 1.65 (1.27-2.15)) even after adjusting for traditional risk factors. Similar statistically significant associations were observed between CKD-RA and other secondary outcomes except for CKD progression.

CONCLUSION

RA was associated with higher mortality among individuals with CKD but not progressive renal decline. Further studies evaluating the mechanisms behind this association are needed. Key Points • Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD) as well as with an increased risk of chronic kidney disease (CKD), also a known cardiovascular risk factor. However, it is not known if RA is an independent predictor of adverse outcomes in patients with CKD • In this study, we observed that CKD patients with RA experience higher mortality as well as an increased risk of CVD compared to patients with CKD without comorbid RA • These data provide rationale for more aggressive monitoring for CVD in patients with CKD and RA. They also underscore the need for determining which interventions can help decrease the burden of mortality in these patients.

Circadian rhythms and renal pathophysiology

The reality of life in modern times is that our internal circadian rhythms are often out of alignment with the light/dark cycle of the external environment. This is known as circadian disruption, and a wealth of epidemiological evidence shows that it is associated with an increased risk for cardiovascular disease. Cardiovascular disease remains the top cause of death in the United States, and kidney disease in particular is a tremendous public health burden that contributes to cardiovascular deaths. There is an urgent need for new treatments for kidney disease; circadian rhythm-based therapies may be of potential benefit. The goal of this Review is to summarize the existing data that demonstrate a connection between circadian rhythm disruption and renal impairment in humans. Specifically, we will focus on chronic kidney disease, lupus nephritis, hypertension, and aging. Importantly, the relationship between circadian dysfunction and pathophysiology is thought to be bidirectional. Here we discuss the gaps in our knowledge of the mechanisms underlying circadian dysfunction in diseases of the kidney. Finally, we provide a brief overview of potential circadian rhythm-based interventions that could provide benefit in renal disease.

Role of Platelets in Chronic Kidney Disease

Platelet-dependent mechanisms for excessive clotting and bleeding in CKD remain undefined. Moreover, platelets' contribution to inflammation, and specifically to CKD, are equally elusive. To date, descriptions of changes in the functional properties of circulating platelets during CKD have provided confusing interpretations. Experimental approaches that can advance our understanding of platelet dysfunction in CKD are needed, and studies that provide mechanistic insights into the dynamic relationships between thrombosis, bleeding, and inflammation associated with CKD will be essential to improve clinical management and outcomes for this vulnerable population. This article summarizes existing literature characterizing platelets in CKD and identifies areas that need further investigation.

The inflammatory state is a risk factor for cardiovascular disease and graft fibrosis in kidney transplantation

Several factors, such as donor brain death, ischemia-reperfusion injury, rejection, infection, and chronic allograft dysfunction, may induce an inflammatory state in kidney transplantation. Furthermore, inflammatory cells, cytokines, growth factors, complement and coagulation cascade create an unbalanced interaction with innate and adaptive immunity, which are both heavily involved in atherogenesis. The crosstalk between inflammation and thrombosis may lead to a prothrombotic state and impaired fibrinolysis in kidney transplant recipients increasing the risk of cardiovascular disease. Inflammation is also associated with elevated levels of fibroblast growth factor 23 and low levels of Klotho, which contribute to major adverse cardiovascular events. Hyperuricemia, glucose intolerance, arterial hypertension, dyslipidemia, and physical inactivity may create a condition called metaflammation that concurs in atherogenesis. Another major consequence of the inflammatory state is the development of chronic hypoxia that through the mediation of interleukins 1 and 6, angiotensin II, and transforming growth factor beta can result in excessive accumulation of extracellular matrix, which can disrupt and replace functional parenchyma, leading to interstitial fibrosis and chronic allograft dysfunction. Lifestyle and regular physical activity may reduce inflammation. Several drugs have been proposed to control the graft inflammatory state, including low-dose aspirin, statins, renin-angiotensin inhibitors, xanthine-oxidase inhibitors, vitamin D supplements, and interleukin-6 blockade. However, no prospective controlled trial with these measures has been conducted in kidney transplantation.

Low High-Sensitivity C-Reactive Protein Level in Korean Patients With Chronic Kidney Disease and Its Predictive Significance for Cardiovascular Events, Mortality, and Adverse Kidney Outcomes: Results From KNOW-CKD

Background Inflammation levels are lower in East Asians than in Western people. We studied the association between high-sensitivity hs-CRP (C-reactive protein) and adverse outcomes in Korean patients with chronic kidney disease. Methods and Results We included 2018 participants from the KNOW-CKD (Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease) between April 2011 and February 2016. The primary outcome was a composite of extended major cardiovascular events (eMACE) or all-cause mortality. The secondary end points were separate outcomes of eMACE, all-cause death, and adverse kidney outcome. We also evaluated predictive ability of hs-CRP for the primary outcome. The median hs-CRP level was 0.60 mg/L. During the mean follow-up of 3.9 years, there were 125 (6.2%) eMACEs and 80 (4.0%) deaths. In multivariable Cox analysis after adjustment of confounders, there was a graded association of hs-CRP with the primary outcome. The hazard ratios for hs-CRPs of 1.0 to 2.99 and ≥3.0 mg/L were 1.33 (95% CI, 0.87-2.03) and 2.08 (95% CI, 1.30-3.33) compared with the hs-CRP of <1.0 mg/L. In secondary outcomes, this association was consistent for eMACE and all-cause death; however, hs-CRP was not associated with adverse kidney outcomes. Finally, prediction models failed to show improvement of predictive performance of hs-CRP compared with conventional factors. Conclusions In Korean patients with chronic kidney disease, the hs-CRP level was low and significantly associated with higher risks of eMACEs and mortality. However, hs-CRP did not associate with adverse kidney outcome, and the predictive performance of hs-CRP was not strong. Registration URL: http://www.clinicaltrials.gov; Unique identifier: NCT01630486.

Reduction in Serum High-Sensitivity C-Reactive Protein Favors Kidney Outcomes in Patients with Impaired Fasting Glucose or Diabetes

OBJECTIVE

We aimed to evaluate whether the reduction in serum high-sensitivity C-reactive protein (hs-CRP) favors kidney outcomes.

METHODS

This study was a subanalysis including patients with impaired fasting glucose or diabetes of the Kailuan cohort study. The predictor was based on two consecutive visits of hs-CRP levels in 2006 and 2008. A total of 3924 patients with hs-CRP ≥ 3 mg/L in 2006 were divided into two groups according to whether the levels of hs-CRP were reduced in 2008: Group 1: no reduction: hs-CRP ≥ 3 mg/L in 2008; Group 2: reduction: hs-CRP < 3 mg/L in 2008. Kidney outcomes include kidney function decline and development and progression of proteinuria and were followed up until the end of 2015.

RESULTS

There were 3905, 2049, and 493 patients included into our analysis for the outcomes of kidney function decline and the development and progression of proteinuria, respectively. A total of 398, 297, and 47 events occurred after 5 years of follow-up, respectively. Cox regression revealed that patients with reduction in hs-CRP have lower risk of kidney function decline (HR 0.71, 95% CI 0.57-0.89, and P = 0.002) and development of proteinuria (0.77, 0.61-0.99, and P = 0.038) after controlling for potential confounders as compared to those with no reduction in hs-CRP levels.

CONCLUSIONS

Reduction in serum hs-CRP levels favors kidney outcomes in patients with impaired fasting glucose or diabetes.

The Cumulative Exposure to High-Sensitivity C-Reactive Protein Predicts the Risk of Chronic Kidney Diseases

BACKGROUND AND OBJECTIVES

This study was to characterize the association of cumulative exposure to increased high-sensitivity C-reactive protein (hs-CRP) with chronic kidney diseases (CKD).

METHODS

We included 35,194 participants with hs-CRP measured at three examinations in 2006, 2008, 2010. Participants were classified into nonexposed group (hs-CRP <3.0 mg/L in all 3 examinations), 1-exposed group (hs-CRP ≥3.0 mg/L in 1 of the 3 examinations), 2-exposed group (hs-CRP ≥3.0 mg/L in 2 of the 3 examinations), and 3-exposed group (hs-CRP ≥3.0 mg/L in 3 examinations). Cox proportional hazards models were used to assess the association of cumulative hs-CRP with incident CKD. CKD includes an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or urinary protein positive.

RESULTS

The study showed the risk of CKD as the number of years of exposure to hs-CRP increases. Participants in 3-exposed group had significantly increased CKD risk with hazard ratio (HR) (95% confidence interval, CI) of 1.70 (1.49-1.93), in comparison with 1.47 (1.34-1.62) for participants in the 2-exposed group, and 1.08 (1.00-1.16) for those in the 1-exposed group (p < 0.01); meanwhile, the similar and significant associations were also observed for eGFR <60 mL/min/1.73 m2, proteinuria positive, in participants of the 3-exposed group in comparison with the nonexposed group, with respective HRs (95% CI) of 1.27 (1.01-1.58) and 2.27 (1.87-2.76).

CONCLUSIONS

Cumulative exposure to hs-CRP was associated with a subsequent increased risk of CKD and was of great value to risk prediction.

The complex effects of adipokines in the patients with kidney disease

Kidney diseases are categorized as the highest prevalent ones with worldwide noticeable incidence. They cause accelerated cardiovascular diseases and noticeable mortalities. Adipose tissue and its messengers, adipokines, are reported to have the highest relationship with end-stage renal diseases or chronic kidney diseases. Over recent years, with shifting of scientists’ mindset from a simple overview of adipose tissue as a fat store to the complex paradigm of this issue as a multipotential secretory organ, the importance of studies on this tissue has emerged.

Does inflammation affect outcomes in dialysis patients?

Chronic, low-grade inflammation is a common comorbid condition in chronic kidney disease (CKD), and particularly in chronic dialysis patients. In this review, we consider the question of whether inflammation affects outcomes in dialysis patients. Levels of proinflammatory cytokines, as well as C-reactive protein, are elevated in chronic dialysis patients. Multiple factors likely contribute to chronic inflammatory activation in kidney disease patients including the uremic milieu, lifestyle and epigenetic influences, infectious and thrombotic events, the dialysis process, and dysbiosis. Increased inflammatory markers in both CKD and chronic dialysis patients are associated with adverse clinical outcomes including all-cause mortality, cardiovascular events, kidney disease progression, protein energy wasting and diminished motor function, cognitive impairment, as well as other adverse consequences including CKD-mineral and bone disorder, anemia, and insulin resistance. Strategies that have been shown to reduce chronic systemic inflammation in CKD and chronic dialysis patients include both pharmacological and nonpharmacological interventions. However, despite evidence that systemic inflammatory markers can be lowered in kidney disease patients treated with various strategies, evidence that this improves clinical outcomes is largely unavailable and represents an important future research direction. Overall, there is strong observational evidence that inflammation is high in chronic dialysis patients and that this is independently associated with numerous adverse clinical outcomes. Targeting inflammation represents a potentially novel and attractive strategy if it can indeed improve adverse outcomes common in this population.

Do sodium-glucose co-transporter-2 inhibitors prevent heart failure with a preserved ejection fraction by counterbalancing the effects of leptin? A novel hypothesis

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce the risk of serious heart failure events in patients with type 2 diabetes, but little is known about mechanisms that might mediate this benefit. The most common heart failure phenotype in type 2 diabetes is obesity-related heart failure with a preserved ejection fraction (HFpEF). It has been hypothesized that the synthesis of leptin in this disorder leads to sodium retention and plasma volume expansion as well as to cardiac and renal inflammation and fibrosis. Interestingly, leptin-mediated neurohormonal activation appears to enhance the expression of SGLT2 in the renal tubules, and SGLT2 inhibitors exert natriuretic actions at multiple renal tubular sites in a manner that can oppose the sodium retention produced by leptin. In addition, SGLT2 inhibitors reduce the accumulation and inflammation of perivisceral adipose tissue, thus minimizing the secretion of leptin and its paracrine actions on the heart and kidneys to promote fibrosis. Such fibrosis probably contributes to the impairment of cardiac distensibility and glomerular function that characterizes obesity-related HFpEF. Ongoing clinical trials with SGLT2 inhibitors in heart failure are positioned to confirm or refute the hypothesis that these drugs may favourably influence the course of obesity-related HFpEF by their ability to attenuate the secretion and actions of leptin.

Implication of Nonalcoholic Fatty Liver Disease, Metabolic Syndrome, and Subclinical Inflammation on Mild Renal Insufficiency

BACKGROUND

Limited information exists about the impact of nonalcoholic fatty liver disease (NAFLD) on mild renal insufficiency. We compared the relative influence of NAFLD, metabolic syndrome (MetS), and subclinical inflammation, alone or in combination, on mild renal insufficiency.

METHODS

This study included 1174 Korean adults. NAFLD was diagnosed using ultrasonography. Mild renal insufficiency was defined as an estimated glomerular filtration rate (eGFR) ≥ 60 and <90 mL/min/1.73 m².

RESULTS

In partial correlation analysis, several components of MetS and liver aminotransferase levels, but not high-sensitivity C-reactive protein (hsCRP), were associated with eGFR. Multivariate logistic regression analysis demonstrated the independent association of NAFLD (P = 0.034) and MetS (P = 0.018) with mild renal insufficiency, but not elevated hsCRP (P = 0.885). Furthermore, NAFLD without the MetS group (odds ratio (95% confidence interval) = 1.56 (1.05-2.34)) or MetS without the NAFLD group (1.82 (1.11-3.00)) was associated with mild renal insufficiency after adjusting for confounding variables. However, individuals with high hsCRP showed no relationship with mild renal insufficiency, irrespective of the existence of NAFLD.

CONCLUSIONS

This study demonstrated that NAFLD and MetS are independently associated with mild renal insufficiency, whereas subclinical inflammation did not affect the risk for mild renal insufficiency in Korean adults.

Renal Aging: Causes and Consequences

Individuals age >65 years old are the fastest expanding population demographic throughout the developed world. Consequently, more aged patients than before are receiving diagnoses of impaired renal function and nephrosclerosis-age-associated histologic changes in the kidneys. Recent studies have shown that the aged kidney undergoes a range of structural changes and has altered transcriptomic, hemodynamic, and physiologic behavior at rest and in response to renal insults. These changes impair the ability of the kidney to withstand and recover from injury, contributing to the high susceptibility of the aged population to AKI and their increased propensity to develop subsequent progressive CKD. In this review, we examine these features of the aged kidney and explore the various validated and putative pathways contributing to the changes observed with aging in both experimental animal models and humans. We also discuss the potential for additional study to increase understanding of the aged kidney and lead to novel therapeutic strategies.

C-Reactive Protein and Risk of ESRD: Results From the Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT)

BACKGROUND

To better understand a potential association of elevated C-reactive protein (CRP) level with progression of chronic kidney disease (CKD), we examined the relationship of CRP level with the development of end-stage renal disease (ESRD) in the Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT).

STUDY DESIGN

Post hoc analysis of a randomized controlled trial.

SETTING & PARTICIPANTS

4,038 patients with type 2 diabetes, CKD, and anemia in TREAT.

PREDICTOR

Baseline serum CRP concentrations.

OUTCOMES

The primary outcome was development of ESRD; secondary outcomes included doubling of serum creatinine level, a composite of ESRD/serum creatinine doubling, and a composite of death or ESRD.

MEASUREMENTS

We fit unadjusted and adjusted Cox regression models to test the association of baseline CRP level with time to the development of the outcomes of interest.

RESULTS

Mean age of participants was 67 years, 43% were men, and 64% were white. Approximately half (48%) the patients had CRP levels > 3.0mg/L; 668 patients developed ESRD, and 1,270 developed the composite outcome of death or ESRD. Compared with patients with baseline CRP levels ≤ 3.0mg/L, those with moderately/markedly elevated CRP levels (≥6.9mg/L; 24% of patients) had a higher adjusted risk for ESRD (HR, 1.32; 95% CI, 1.07-1.63) and the composite outcome of death or ESRD (HR, 1.41; 95% CI, 1.21-1.64). Although nonsignificant, similar trends were noted in competing-risk models.

LIMITATIONS

Results may not be generalizable to nondiabetic CKD or diabetic CKD in the absence of anemia.

CONCLUSIONS

Elevated baseline CRP levels are common in type 2 diabetic patients with anemia and CKD and are associated with the future development of ESRD and the composite of death or ESRD.

FGF23 from bench to bedside

There is a strong association between elevated circulating fibroblast growth factor-23 (FGF23) levels and adverse outcomes in patients with chronic kidney disease (CKD) of all stages. Initially discovered as a regulator of phosphate and vitamin D homeostasis, FGF23 has now been implicated in several pathophysiological mechanisms that may negatively impact the cardiovascular and renal systems. FGF23 is purported to have direct (off-target) effects in the myocardium, as well as canonical effects on FGF receptor/α-klotho receptor complexes in the kidney to activate the renin-angiotensin-aldosterone system, modulate soluble α-klotho levels, and increase sodium retention, to cause left ventricular hypertrophy (LVH). Conversely, FGF23 could be an innocent bystander produced in response to chronic inflammation or other processes associated with CKD that cause LVH and adverse cardiovascular outcomes. Further exploration of these complex mechanisms is needed before modulation of FGF23 can become a legitimate clinical target in CKD.

Association of C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 with chronic kidney disease

BACKGROUND

We studied the association of inflammatory biomarkers including C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) with chronic kidney disease (CKD).

METHODS

We conducted a case-control study among 201 CKD patients and 201 community-based controls in the greater New Orleans area. CKD was defined as estimated-glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) or albuminuria ≥30 mg/24-h. Serum CRP, TNF-α, and IL-6 were measured using standard methods. Multivariable regression models were used to examine associations between the inflammatory biomarkers and CKD adjusting for important CKD risk factors, history of cardiovascular disease, and use of antihypertensive, antidiabetic, and lipid-lowering agents and aspirin.

RESULTS

The multivariable-adjusted medians (interquartile-range) were 2.91 (1.47, 5.24) mg/L in patients with CKD vs. 1.91 (0.99, 3.79) mg/L in controls without CKD (p = 0.39 for group difference) for CRP; 1.86 (1.51, 2.63) pg/mL vs. 1.26 (1.01, 1.98) pg/mL (p < 0.0001) for TNF-α; and 2.53 (1.49, 4.42) pg/mL vs. 1.39 (0.95, 2.15) pg/mL (p = 0.04) for IL-6, respectively. Compared to the lowest tertile, the highest tertile of TNF-α (OR 7.1, 95% CI 3.2 to 15.5) and IL-6 (OR 2.5, 95% CI 1.1 to 5.5) were significantly associated with higher odds of CKD in multivariable-adjusted models. Additionally, higher TNF-α and IL-6 were independently and significantly associated with lower eGFR and higher albuminuria.

CONCLUSIONS

Our data suggest that TNF-α and IL-6, but not CRP, are associated with the prevalence and severity of CKD, independent from established CKD risk factors, history of cardiovascular disease, and use of antihypertensive, antidiabetic, and lipid-lowering agents and aspirin.

Elevated serum leptin, adiponectin and leptin to adiponectin ratio is associated with chronic kidney disease in Asian adults

Background

Adiponectin and leptin, two of the key cytokines secreted by adipocytes, have been shown to be associated with cardiovascular disease. However, the association of these adipocytokines with chronic kidney disease (CKD) is not clear. We examined the association of serum adiponectin, leptin levels and leptin to adiponectin ratio (LAR) with CKD in a population-based sample of Asian adults.

Methods

We conducted a case-control study (450 CKD cases and 920 controls matched for age, sex and ethnicity) involving Chinese and Indian adults aged 40–80 years who participated in the Singapore Epidemiology of Eye Diseases Study (2007–2011). CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73m² from serum creatinine. Serum adiponectin and leptin levels were measured using commercially available ELISA. Odds ratio of CKD associated with elevated adiponectin and leptin levels were estimated using logistic regression models adjusted for age, gender, ethnicity, education, smoking, body mass index, diabetes, blood pressure, total and HDL cholesterol.

Results

CKD cases had higher levels of leptin (mean [SD] 9.7 [11.5] vs.16.9 [20.2] ng/mL, p<0.0001) and adiponectin (10.4 [7.4] vs. 9.2 [4.2], p = 0.001) compared to controls. In multi-variable models, compared to those in the lowest quartile, the OR (95% confidence interval) of CKD among those in the highest quartile were: 6.46 (3.84, 10.88), 1.94 (1.32–2.85) and 2.88 (1.78–4.64) for leptin, adiponectin and LAR. Similar associations were also observed when adiponectin and leptin were analyzed as continuous variables. This positive association of serum adiponectin, leptin and LAR with CKD was consistently present in subgroups of gender, ethnicity, diabetes, hypertension and overweight status (all P-interaction >0.1).

Conclusions

Higher levels of serum adiponectin, leptin and LAR were positively associated with CKD independent of traditional risk factors in this Asian population.

The association of leptin and homocysteine with renal function impairment in a population of Taiwanese adults

BACKGROUND & AIMS

Higher levels of leptin and homocysteine (Hcy) have been evaluated as risk factors of chronic kidney disease in patients and general population. The aim of this study was to examine gender differences in the associations of leptin and Hcy levels and renal function a representative healthy young population in Taiwan.

METHODS

The participants aged ≥18 years who underwent health examinations were included and categorized into three groups by gender-specific tertiles of leptin and Hcy levels. Estimated glomerular filtration rates (eGFR) were estimated according to the modified equation of Modification of Diet in Renal Disease (MDRD).

RESULTS

A higher mean Hcy level was found in male subjects than females. Mean values of metabolic syndrome risk factors significantly elevated with increasing leptin levels in both genders. Both male and female subjects with higher plasma Hcy levels were more likely to have a lower eGFR. Plasma Hcy levels were significantly negatively correlated with eGFR in linear regression models adjusted for age and smoking. The associations persisted even after mean arterial pressure and fasting plasma glucose were included for adjustments both genders. Plasma Hcy level was negatively associated eGFR and the association was more profound for females.

CONCLUSIONS

Leptin levels did not reveal strong or consistent evidence to support a significant association with eGFR. Hcy had a more decisive effect on renal function impairment than leptin and may be considered a more sensitive biomarker for Taiwanese adults.

Circulating adipocytokines and chronic kidney disease

Background

Adipokines have been associated with atherosclerotic heart disease, which shares many common risk factors with chronic kidney disease (CKD), but their relationship with CKD has not been well characterized.

Methods

We investigated the association of plasma leptin, resistin and adiponectin with CKD in 201 patients with CKD and 201 controls without. CKD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² or presence of albuminuria. Quantile regression and logistic regression models were used to examine the association between adipokines and CKD adjusting for multiple confounding factors.

Results

Compared to controls, adjusted median leptin (38.2 vs. 17.2 ng/mL, p<0.0001) and adjusted mean resistin (16.2 vs 9.0 ng/mL, p<0.0001) were significantly higher in CKD cases. The multiple-adjusted odds ratio (95% confidence interval) of CKD comparing the highest tertile to the lower two tertiles was 2.3 (1.1, 4.9) for leptin and 12.7 (6.5, 24.6) for resistin. Median adiponectin was not significantly different in cases and controls, but the odds ratio comparing the highest tertile to the lower two tertiles was significant (1.9; 95% CI, 1.1, 3.6). In addition, higher leptin, resistin, and adiponectin were independently associated with lower eGFR and higher urinary albumin levels.

Conclusions

These findings suggest that adipocytokines are independently and significantly associated with the risk and severity of CKD. Longitudinal studies are warranted to evaluate the prospective relationship of adipocytokines to the development and progression of CKD.

The natural history of, and risk factors for, progressive chronic kidney disease (CKD): the Renal Impairment in Secondary care (RIISC) study; rationale and protocol

BACKGROUND

Chronic kidney disease (CKD) affects up to 16% of the adult population and is associated with significant morbidity and mortality. People at highest risk from progressive CKD are defined by a sustained decline in estimated glomerular filtration rate (eGFR) and/or the presence of significant albuminuria/proteinuria and/or more advanced CKD. Accurate mapping of the bio-clinical determinants of this group will enable improved risk stratification and direct the development of better targeted management for people with CKD.

METHODS/DESIGN

The Renal Impairment In Secondary Care study is a prospective, observational cohort study, patients with CKD 4 and 5 or CKD 3 and either accelerated progression and/or proteinuria who are managed in secondary care are eligible to participate. Participants undergo a detailed bio-clinical assessment that includes measures of vascular health, periodontal health, quality of life and socio-economic status, clinical assessment and collection of samples for biomarker analysis. The assessments take place at baseline, and at six, 18, 36, 60 and 120 months; the outcomes of interest include cardiovascular events, progression to end stage kidney disease and death.

DISCUSSION

The determinants of progression of chronic kidney disease are not fully understood though there are a number of proposed risk factors for progression (both traditional and novel). This study will provide a detailed bio-clinical phenotype of patients with high-risk chronic kidney disease (high risk of both progression and cardiovascular events) and will repeatedly assess them over a prolonged follow up period. Recruitment commenced in Autumn 2010 and will provide many outputs that will add to the evidence base for progressive chronic kidney disease.

Inflammation and the pathogenesis of diabetic nephropathy

The most problematic issue in clinical nephrology is the relentless and progressive increase in patients with ESRD (end-stage renal disease) worldwide. The impact of diabetic nephropathy on the increasing population with CKD (chronic kidney disease) and ESRD is enormous. Three major pathways showing abnormality of intracellular metabolism have been identified in the development of diabetic nephropathy: (i) the activation of polyol and PKC (protein kinase C) pathways; (ii) the formation of advanced glycation end-products; and (iii) intraglomerular hypertension induced by glomerular hyperfiltration. Upstream of these three major pathways, hyperglycaemia is the major driving force of the progression to ESRD from diabetic nephropathy. Downstream of the three pathways, microinflammation and subsequent extracellular matrix expansion are common pathways for the progression of diabetic nephropathy. In recent years, many researchers have been convinced that the inflammation pathways play central roles in the progression of diabetic nephropathy, and the identification of new inflammatory molecules may link to the development of new therapeutic strategies. Various molecules related to the inflammation pathways in diabetic nephropathy include transcription factors, pro-inflammatory cytokines, chemokines, adhesion molecules, Toll-like receptors, adipokines and nuclear receptors, which are candidates for the new molecular targets for the treatment of diabetic nephropathy. Understanding of these molecular pathways of inflammation would translate into the development of anti-inflammation therapeutic strategies.

Not all inflammatory markers are linked to kidney function: results from a population-based study

BACKGROUND

Several studies have reported increased levels of inflammatory biomarkers in chronic kidney disease (CKD), but data from the general population are sparse. In this study, we assessed levels of the inflammatory markers C-reactive protein (hsCRP), tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 across all ranges of renal function.

METHODS

We conducted a cross-sectional study in a random sample of 6,184 Caucasian subjects aged 35-75 years in Lausanne, Switzerland. Serum levels of hsCRP, TNF-α, IL-6, and IL-1β were measured in 6,067 participants (98.1%); serum creatinine-based estimated glomerular filtration rate (eGFR(creat), CKD-EPI formula) was used to assess renal function, and albumin/creatinine ratio on spot morning urine to assess microalbuminuria (MAU).

RESULTS

Higher serum levels of IL-6, TNF-α and hsCRP and lower levels of IL-1β were associated with a lower renal function, CKD (eGFR(creat) <60 ml/min/1.73 m(2); n = 283), and MAU (n = 583). In multivariate linear regression analysis adjusted for age, sex, hypertension, smoking, diabetes, body mass index, lipids, antihypertensive and hypolipemic therapy, only log-transformed TNF-α remained independently associated with lower renal function (β -0.54 ±0.19). In multivariate logistic regression analysis, higher TNF-α levels were associated with CKD (OR 1.17; 95% CI 1.01-1.35), whereas higher levels of IL-6 (OR 1.09; 95% CI 1.02-1.16) and hsCRP (OR 1.21; 95% CI 1.10-1.32) were associated with MAU.

CONCLUSION

We did not confirm a significant association between renal function and IL-6, IL-1β and hsCRP in the general population. However, our results demonstrate a significant association between TNF-α and renal function, suggesting a potential link between inflammation and the development of CKD. These data also confirm the association between MAU and inflammation.

Markers of inflammation predict the long-term risk of developing chronic kidney disease: a population-based cohort study

In animal models, inflammatory processes have been shown to have an important role in the development of kidney disease. In humans, however, the independent relation between markers of inflammation and the risk of chronic kidney disease (CKD) is not known. To clarify this, we examined the relationship of several inflammatory biomarker levels (high-sensitivity C-reactive protein, tumor necrosis factor-α receptor 2, white blood cell count, and interleukin-6) with the risk of developing CKD in a population-based cohort of up to 4926 patients with 15 years of follow-up. In cross-sectional analyses, we found that all these inflammation markers were positively associated with the outcome of interest, prevalent CKD. However, in longitudinal analyses examining the risk of developing incident CKD among those who were CKD-free at baseline, only tumor necrosis factor-α receptor 2, white blood cell count, and interleukin-6 levels (hazard ratios comparing highest with the lowest tertile of 2.10, 1.90, and 1.45, respectively), and not C-reactive protein (hazard ratio 1.09), were positively associated with incident CKD. Thus, elevations of most markers of inflammation predict the risk of developing CKD. Each marker should be independently verified.

Inflammation, kidney function and albuminuria in the Framingham Offspring cohort

BACKGROUND

Inflammation and chronic kidney disease (CKD) are both associated with cardiovascular disease (CVD). Whether inflammatory biomarkers are associated with kidney function and albuminuria after accounting for traditional CVD risk factors is not completely understood.

METHODS

The sample comprised Framingham Offspring cohort participants (n = 3294, mean age 61, 53% women) who attended the seventh examination cycle (1998-2001). Inflammatory biomarkers [C-reactive protein (CRP), tumour necrosis factor (TNF)-alpha, interleukin-6, TNF receptor 2 (TNFR2), intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), P-selectin, CD-40 ligand, osteoprotegerin, urinary isoprostanes, myeloperoxidase and fibrinogen] were measured on fasting blood samples. Serum creatinine-based estimated glomerular filtration rate (eGFR) and serum cystatin C concentration were used to assess kidney function. Urinary albumin-to-creatinine ratio (UACR) was used to assess albuminuria. Linear or logistic regression was used to test associations between biomarkers and kidney measures.

RESULTS

Chronic kidney disease (CKD), defined as eGFR < 59/64 mL/min/1.73 m(2) in women/men, was present in 8.8% (n = 291) of participants. TNF-alpha, interleukin-6, TNFR2, MCP-1, osteoprotegerin, myeloperoxidase and fibrinogen were higher among individuals with CKD; all biomarkers except for urinary isoprostanes were elevated in higher cystatin C quartiles; and TNF-alpha, interleukin-6, TNFR2, ICAM-1 and osteoprotegerin were elevated in higher UACR quartiles-all assessed after multivariable adjustment. Almost 6% and 17% of variability in TNFR2 were explained by CKD status and higher cystatin C quartiles, respectively.

CONCLUSIONS

Biomarkers of inflammation are associated with kidney function and albuminuria. In particular, substantial variability in soluble TNFR2 is explained by CKD and cystatin C.

Association between baseline kidney function and change in CRP: an analysis of the cardiovascular health study

BACKGROUND

In cross-sectional analyses, C-reactive protein (CRP) levels are inversely related to levels of kidney function. The relationship between kidney function and subsequent changes in CRP is unknown.

METHODS

We studied 4,364 individuals from the Cardiovascular Health Study, a longitudinal cohort of community-dwelling older adults. Baseline eGFRcys was estimated using cystatin C. CRP was measured at baseline and after 3 and 7 years of follow-up; slopes of change in CRP were calculated.

RESULTS

The mean (SD) age of the cohort was 72 (5.2) years; mean (SD) eGFRcys was 78.9 (18.4) ml/min/1.73 m(2). The median (interquartile range IQR) baseline CRP was 2.39 (1.22, 4.33) mg/l; the median (IQR) yearly change in CRP was -0.0051 (-0.020 to 0.27) mg/l/year. After adjustment for demographic characteristics and the initial level of CRP, each standard deviation lower baseline eGFR was associated with a small and non-significant yearly increase in CRP (0.032 mg/l/year; 95% CI: -0.005 to 0.070, p = 0.094).

CONCLUSIONS

We did not find a relationship between eGFR and subsequent changes in CRP. The association between kidney function and CRP in cross-sectional analyses may reflect unmeasured confounding by atherosclerosis; alternatively, the burden of comorbidity and interval mortality in this population may have masked a stronger longitudinal association between kidney function and change in CRP. Further study in younger populations may clarify whether impaired kidney function leads to change in inflammation over time.

Lipid and inflammatory biomarkers and kidney function decline in type 2 diabetes

AIMS/HYPOTHESIS

Potentially modifiable biomarkers may influence the decline in estimated GFR (eGFR), but few data are currently available in type 2 diabetic adults.

METHODS

We studied 516 women with type 2 diabetes in the Nurses' Health Study with data on lipid and inflammatory biomarkers from plasma collected in 1989 and plasma creatinine in samples collected in 1989 and 2000. An estimated GFR decline of >or=25% over 11 years was the outcome of interest.

RESULTS

Comparing the highest with the lowest quartile, soluble tumour necrosis factor receptor 2 (sTNFR-2) was independently associated with an eGFR decline of >or=25% (multivariate OR 5.81; 95% CI 2.90-11.65); this association was stronger in obese women (OR 16.76; 95% CI 4.69-59.90 for BMI >or=30 kg/m(2); OR 2.78, 95% CI 1.12-6.89 for BMI <30 kg/m(2); p for interaction = 0.02). No lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, non-HDL-cholesterol, triacylglycerols, lipoprotein(a), or apolipoprotein B) or other markers of inflammation (C-reactive protein, fibrinogen, E-selectin, intracellular cell adhesion molecule 1, leptin or adiponectin) were significantly associated with eGFR decline after multivariable adjustment.

CONCLUSIONS/INTERPRETATION

Elevated sTNFR-2 levels may be an important and potentially modifiable risk factor for eGFR decline in type 2 diabetes, especially in those with a BMI of >or=30 kg/m(2).

Prevalence of atrial fibrillation and its predictors in nondialysis patients with chronic kidney disease

BACKGROUND AND OBJECTIVES

Chronic kidney disease (CKD) increases systemic inflammation, which is implicated in development and maintenance of atrial fibrillation (AF); therefore, we hypothesized that the prevalence of AF would be increased among nondialysis patients with CKD. This study also reports independent predictors of the presence of AF in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective, cross-sectional analysis of 1010 consecutive nondialysis patients with CKD from two community-based hospitals was conducted. Estimated GFRs (eGFRs) were calculated using the Modification of Diet in Renal Disease (MDRD) equation. Multivariate logistic regression was used to determine independent predictors.

RESULTS

Of 1010 nondialysis patients with CKD, 214 (21.2%) had AF. Patients with AF were older than patients without AF (76 +/- 11 versus 63 +/- 15 yr). The prevalence of AF among white patients (42.7%) was higher than among black patients (12.7%) or other races (5.7%). In multivariate analyses, age, white race, increasing left atrial diameter, lower systolic BP, and congestive heart failure were identified as independent predictors of the presence of AF. Although serum high-sensitivity C-reactive protein levels were elevated in our population (5.2 +/- 7.4 mg/L), levels did not correlate with the presence of AF or with eGFR. Finally, eGFR did not correlate with the presence of AF in our population.

CONCLUSIONS

The prevalence of AF was increased in our population, and independent predictors were age, white race, increasing left atrial diameter, lower systolic BP, and congestive heart failure.

Inflammatory biomarkers and decline in kidney function in the elderly: the Cardiovascular Health Study

BACKGROUND

Cross-sectional studies have demonstrated a consistent and linear association between circulating inflammatory markers and kidney function. The objective of this study was to determine whether elevated markers of inflammation are independently associated with longitudinal kidney function decline.

METHODS

This study included 4128 subjects from the Cardiovascular Health Study. Cystatin C was measured at baseline, 3 years later and 7 years later; eligible subjects had at least two measures. Cystatin C-based estimated glomerular filtration rate (eGFR(cysC)) was estimated, and rapid kidney function decline was defined as an annual loss of eGFR(cysC) >3 mL/min/1.73 m(2). Predictors included ten inflammatory and procoagulant biomarkers: C-reactive protein, interleukin-6, intercellular adhesion molecule-1, white blood cell count, fibrinogen, factor VII, factor VIII, D-dimer, plasmin-antiplasmin complex and serum albumin.

RESULTS

During the study, 1059 subjects (26%) had a rapid decline in kidney function. In contrast to the other nine inflammatory or procoagulant biomarkers, serum albumin had a consistent and inverse association with rapid kidney function decline [final adjusted logistic regression model: 1.14-fold increased odds (95% CI 1.06-1.23) of rapid decline per standard deviation lower albumin]. The lowest quartile of albumin had an odds ratio of 1.55 (95% CI 1.23-1.96) for rapid decline compared with the highest quartile. These associations persisted after adjusting the albumin models for CRP, IL-6 and fibrinogen.

CONCLUSIONS

In contrast to nine other inflammatory and procoagulant markers, only lower baseline levels of serum albumin were consistently associated with a rapid decline in kidney function, as measured by cystatin C-based eGFR.

Inflammation in chronic kidney disease: role in the progression of renal and cardiovascular disease

Inflammation is the response of the vasculature or tissues to various stimuli. An acute and chronic pro-inflammatory state exists in patients with chronic kidney disease (CKD), contributing substantially to morbidity and mortality. There are many mediators of inflammation in adults with CKD and end-stage kidney disease (ESKD), including hypoalbuminemia/malnutrition, atherosclerosis, advanced oxidation protein products, the peroxisome proliferators-activated receptor, leptin, the thiobarbituric acid reactive system, asymmetric dimethyl arginine, iron, fetuin-A, and cytokines. Inflammation contributes to the progression of CKD by inducing the release of cytokines and the increased production and activity of adhesion molecules, which together contribute to T cell adhesion and migration into the interstitium, subsequently attracting pro-fibrotic factors. Inflammation in CKD also causes mortality from cardiovascular disease by contributing to the development of vascular calcifications and endothelial dysfunction. Similar to the situation in adults, cardiovascular disease in pediatric CKD is linked to inflammation: abnormal left ventricular wall geometry is positively associated with markers of inflammation. This review focuses on traditional and novel mediators of inflammation in CKD and ESKD, and the deleterious effect inflammation has on the progression of renal and cardiovascular disease.

Potential Benefits of Renal Diets on Cardiovascular Risk Factors in Chronic Kidney Disease Patients

Dietary manipulation, including protein, phosphorus, and sodium restriction, when coupled with the vegetarian nature of the renal diet and ketoacid supplementation can potentially exert a cardiovascular protective effect in chronic renal failure patients by acting on both traditional and nontraditional cardiovascular risk factors. Blood pressure control may be favored by the reduction of sodium intake and by the vegetarian nature of the diet, which is very important also for lowering serum cholesterol and improving plasma lipid profile. The low protein and phosphorus intake has a crucial role for reducing proteinuria and preventing and reversing hyperphosphatemia and secondary hyperparathyroidism, which are major causes of the vascular calcifications, cardiac damage, and mortality risk of uremic patients. The reduction of nitrogenous waste products and lowering of serum PTH levels may also help ameliorate insulin sensitivity and metabolic control in diabetic patients, as well as increase the responsiveness to erythropoietin therapy, thus allowing greater control of anemia. Protein-restricted diets may have also anti-inflammatory and anti-oxidant properties. Thus, putting aside the still debatable effects on the progression of renal disease and the more admitted effects on uremic signs and symptoms, it is possible that a proper nutritional treatment early in the course of renal disease may be useful also to reduce the cardiovascular risk in the renal patient. However, conclusive data cannot yet be drawn because quality studies are lacking in this field; future studies should be planned to assess the effect of renal diets on hard outcomes, as cardiovascular events or mortality.

Leptin and lipid metabolism in chronic kidney failure

OBJECTIVE

In the general population, leptin has been associated with atherosclerosis and has been shown to interfere with lipoprotein profiles. Patients with chronic renal failure are at increased risk of cardiovascular disease and display alterations in both lipoprotein and leptin levels. The aim of this study was to investigate the relationship between leptin and the lipoprotein profile in non-dialyzed patients with chronic kidney disease (CKD).

MATERIAL AND METHODS

Leptin and lipid and lipoprotein concentrations were studied in 73 CKD patients and in 68 healthy controls in a cross-sectional case-control design.

RESULTS

The mean leptin levels were increased in the CKD patients (24.0 (SD 37.1) ng/mL) compared to those in controls (9.0 (SD 8.5) ng/mL) (p = 0.008). Also, the ratio between leptin levels and body mass index (leptin/BMI) was increased in CKD patients (mean 0.80 (SD 1.03)) compared to that in controls (0.31 (SD 0.24)) (p = 0.001). In linear regression analysis, leptin independently predicted total cholesterol and triglycerides in CKD patients (p = 0.010 and p = 0.001, respectively) and ratio between total and HDL cholesterol (Chol/HDL) in controls (p = 0.024). Furthermore, in CKD patients, the leptin/BMI predicted the variation in total cholesterol and triglycerides (p = 0.010 and p = 0.002, respectively).

CONCLUSIONS

Leptin concentrations and leptin/BMI were elevated in CKD patients compared to those in controls. Leptin levels in both study groups, and leptin/BMI in the CKD group, were associated with atherogenic lipid profiles, which may contribute to the elevated cardiovascular risk that has been linked to hyperleptinaemia.

Inflammation, hemostasis, and the risk of kidney function decline in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Inflammation and hemostasis may increase the risk of kidney function decline; however, data from prospective studies are sparse.

STUDY DESIGN

The Atherosclerosis Risk in Communities (ARIC) Study, a prospective observational cohort.

SETTING & PARTICIPANTS

We used data from 14,854 middle-aged adults from 4 different US communities.

PREDICTOR

Markers of inflammation and hemostasis were examined.

OUTCOMES & MEASUREMENTS

The risk of kidney function decrease associated with these markers was studied. Glomerular filtration rate (GFR) was calculated from serum creatinine levels using the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation. Chronic kidney disease (CKD) was defined as: (1) a decrease in estimated GFR to less than 60 mL/min/1.73 m2 from greater than 60 mL/min/1.73 m2 at baseline, or (2) a hospitalization discharge or death coded for CKD. Serum creatinine was measured at baseline and the 3- and 9-year follow-up visits. Hazard ratios (HRs) of CKD associated with increased levels of inflammatory and hemostatic variables were estimated by using multivariate Cox proportional hazards regression.

RESULTS

1,787 cases of CKD developed between 1987 and 2004. After adjusting for demographics, smoking, blood pressure, diabetes, lipid levels, prior myocardial infarction, antihypertensive use, alcohol use, year of marker measurement, and baseline renal function using estimated GFR, the risk of incident CKD increased with increasing quartiles of white blood cell count (HR quartile 4 versus quartile 1, 1.30; 95% confidence interval [CI], 1.12 to 1.50; P trend = 0.001), fibrinogen (HR, 1.25; 95% CI, 1.09 to 1.44; P < 0.001), von Willebrand factor (HR, 1.46; 95% CI, 1.26 to 1.68; P < 0.001), and factor VIIIc (HR, 1.39; 95% CI, 1.20 to 1.60; P < 0.001). A strong inverse association was found between serum albumin level and risk of CKD (HR, 0.63; 95% CI, 0.55 to 0.72; P < 0.001). No independent association was found with factor VIIc level.

LIMITATIONS

Although we lacked a direct measure of kidney function, associations were robust to case definitions.

CONCLUSIONS

Markers of inflammation and hemostasis are associated with greater risk of kidney function decrease. Findings suggest that inflammation and hemostasis are antecedent pathways for CKD.

Experiences with acute kidney injury complicating non-fulminant hepatitis A

AIM

To describe the clinical features and to identify factors related to development of acute kidney injury in acute hepatitis A patients.

METHODS

The study and control groups consisted of 21 and 425 patients who did or did not develop acute kidney injury, respectively, after acute hepatitis A from January 1997 to May 2007.

RESULTS

There were 13 men and eight women; their mean age at diagnosis was 28.8 +/- 8.2 years in the study group. Peak values for renal and liver function impairment consisted of a median serum creatinine of 4.6 mg/dL (range, 1.5-15.3 mg/dL) on day 6 (range, days 1-20) and a median total bilirubin of 10.7 mg/dL (range, 2.6-57.5 mg/dL) on day 8 (range, day 1-19). Serum creatinine concentrations returned to baseline level by a median of 16 days and total bilirubin levels returned to normal by a median of 62 days. Six of 21 (29%) patient underwent haemodialysis. Renal biopsies performed in two patients showed acute tubular necrosis and interstitial nephritis, respectively. Logistic regression analysis showed that a lower haematocrit, the presence of coagulopathy and high C-reactive protein concentration on admission, and higher peak bilirubin value during the illness were associated with development of acute kidney injury.

CONCLUSION

Acute hepatitis A should be considered in the differential diagnosis of patients with acute kidney injury, even without fulminant hepatic failure. A lower haematocrit, the presence of coagulopathy and high C-reactive protein level at presentation, and higher peak bilirubin level during the illness were associated with development of acute kidney injury in acute hepatitis A patients.

Impact of subclinical carotid atherosclerosis on incident chronic kidney disease in the elderly

BACKGROUND

Cardiovascular disease (CVD) is increased in persons with chronic kidney disease (CKD); however, no prospective studies have examined carotid intima-media thickness (CIMT) as a risk factor for CKD.

METHODS

A total of 2751 participants who were in the Intervention Project on Cerebrovascular Diseases and Dementia in the community of Ebersberg, Bavaria study and had normal baseline kidney function composed the study cohort. Measures of kidney function were estimated glomerular filtration rate (eGFR) using the Cockcroft-Gault formula in mL/min/1.73 m(2). The main outcome measure was incident CKD defined as an eGFR < 60 mL/min/1.73 m(2) at study year 2 among those with an eGFR >or= 60 mL/min/1.73 m(2) at baseline. Multivariate Cox regression models were used to assess the association between CIMT and incident CKD.

RESULTS

In multivariate analysis, there was a significant and graded association in eGFR decline, -8 +/- 21, -10 +/- 22, -11 +/- 12 and -15 +/- 11 mL/min/1.73 m(2) for the baseline CIMT quartiles 1 (<0.66 mm), 2 (0.66-0.77 mm), 3 (0.77-0.88 mm) and 4 (>0.88 mm), respectively (P for trend: 0.01), during the 2-year follow-up period. Subjects with a baseline CIMT in the fourth quartile developed a significant decrease in eGFR as compared with subjects with a baseline CIMT in the first quartile (P < 0.01). After adjustment for confounding factors, the baseline CIMT remained a predictor for the occurrence of CKD [hazard ratio, 1.17; 95% confidence interval (CI), 1.08-1.30].

CONCLUSIONS

Increases in CIMT, as measured non-invasively by ultrasonography, are directly associated with an increased risk of CKD in elderly individuals.

Relation of low glomerular filtration rate to metabolic disorders in individuals without diabetes and with normoalbuminuria

BACKGROUND AND OBJECTIVES

Microalbuminuria increases cardiovascular risk and is considered a metabolic disorder. Low glomerular filtration rate is also associated with increased cardiovascular risk, but the relation of low glomerular filtration rate to metabolic disorders is not well understood.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Designed as a cross-sectional, epidemiologic study, the Insulin Resistance Atherosclerosis Study was conducted in four centers: San Antonio (Texas), San Luis Valley (Colorado), and Oakland and Los Angeles (California). The Modification of Diet in Renal Disease equation was used to classify individuals without diabetes and with normoalbuminuria (n = 856; age 40 to 69 yr) by the presence or absence of low glomerular filtration rate (<60 ml/min per 1.73 m(2)). A direct marker of insulin resistance, the insulin sensitivity index, was measured by the frequently sampled intravenous glucose tolerance test.

RESULTS

Low glomerular filtration rate was related to hypertension and the metabolic syndrome. Low glomerular filtration rate was associated with fasting insulin concentration and insulin sensitivity index. Low glomerular filtration rate was also associated with insulin concentration after adjustment for potential determinants of glomerular filtration rate but was not associated with insulin sensitivity index.

CONCLUSIONS

Low glomerular filtration rate is associated with increased insulin concentration in individuals without diabetes and with normoalbuminuria. Longitudinal analyses are needed to determine whether insulin concentration (insulin resistance) precedes the deterioration of renal function.

Role of adipose tissue in determining muscle mass in patients with chronic kidney disease

OBJECTIVE

Malnutrition is a powerful predictor of mortality in chronic kidney disease (CKD). However, its etiology is unclear. We hypothesized that the adipocyte-derived proteins leptin and adiponectin, inflammation (as measured by C-reactive protein, CRP), and insulin resistance (as measured by homeostasis model assessment, HOMA), implicated in the malnutrition-inflammation complex syndrome commonly seen in maintenance dialysis patients, would be associated with the loss of muscle mass in earlier stages of CKD. Arm muscle area was used as an indicator of muscle mass.

PATIENTS AND SETTING

The Modification of Diet in Renal Disease Study cohort of people with CKD stages 3 and 4 was used for analysis (N = 780).

MAIN OUTCOME MEASURES

Regression models were carried out to examine the relationships of leptin, adiponectin, CRP, and HOMA with arm muscle area (the main study outcome).

RESULTS

Arm muscle area was 39 +/- 15 cm(2) (mean +/- SD), and adiponectin levels were 13 +/- 7 microg/mL. Median and interquartile range (IQR) concentrations were: 9.0 (13.6) ng/mL for leptin, 2.3 (4.9) mg/L for CRP, and 2.4 (2.0) for HOMA. Higher leptin (beta coefficient and 95% confidence interval, -6.9 [-8.7 to -5.1], P < .001) and higher CRP (beta coefficient and 95% confidence interval, -2.7 [-3.9 to -1.4], P < .001) were associated with lower arm muscle area. There was a trend toward lower arm muscle area with higher adiponectin (P = .07), but no association with HOMA (P = .80).

CONCLUSION

Leptin and CRP were associated with lower muscle mass in subjects with CKD at stages 3 and 4. Further studies are needed to understand the mechanisms underlying these associations, and to develop targeted interventions for this patient population.

Prevalence and characteristics of a family history of end-stage renal disease among adults in the United States population: Reasons for Geographic and Racial Differences in Stroke (REGARDS) renal cohort study

This report describes the prevalence and characteristics of people with a family history of ESRD in a first-degree relative (FH-ESRD). This is a cross-sectional study of individuals in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, a population-based sample of US residents who are 45 yr and older. FH-ESRD was ascertained at baseline among 12,030 participants of the cohort, and multivariate logistic regression was used to identify characteristics that were independently associated with FH-ESRD. FH-ESRD was reported by 9.5% of participants. Individual characteristics that were independently associated with FH-ESRD included black race (odds ratio [OR] 2.14; 95% confidence interval [CI] 1.82 to 2.53); female gender (OR 1.28; 95% CI 1.08 to 1.51); a history of diabetes (OR 1.22; 95% CI 1.02 to 1.47); a 1-SD change in the log of the C-reactive protein level (OR 1.10; 95% CI 1.01 to 1.19); and World Health Organization body mass index weight categories normal (OR 2.11; 95% CI 0.66 to 6.79), overweight (OR 2.64; 95% CI 0.82 to 8.42), and obese (OR 3.48; 95% CI 1.09 to 11.1) compared with underweight. Black but not white individuals with FH-ESRD were more likely to have an estimated GFR <60 ml/min per 1.73 m(2). There is a high prevalence of FH-ESRD among US adults, and the prevalence of FH-ESRD was higher among lack individuals. Individuals with a positive family history were more likely to have diabetes and to be obese. If confirmed, then these findings suggest that individuals with FH-ESRD may benefit from interventions to improve the detection and treatment of chronic kidney disease risk factors such as diabetes and obesity.

Inflammation in end-stage renal disease: the hidden enemy

Cardiovascular disease (CVD) remains the major cause of morbidity and mortality in end-stage renal disease (ESRD) patients. As traditional risk factors cannot alone explain the unacceptable high prevalence and incidence of CVD in this high-risk population, inflammation (interrelated to insulin resistance, oxidative stress, wasting and endothelial dysfunction) has been suggested to be a significant contributor. Indeed, several different inflammatory biomarkers, such as high sensitivity C-reactive protein (hs-CRP), have been shown to independently predict mortality in ESRD patients. As CRP is so strongly associated with vascular disease it has been suggested that this hepatic-derived protein is not only a marker, but also a mediator, of vascular disease. Although in vitro data from studies on endothelial cells, monocytes-macrophages and smooth muscle cells support a direct role for CRP in atherogenesis, data from studies performed in vivo have been controversial. The causes of the highly prevalent state of inflammation in ESRD are multiple, including inflammatory signals associated with the dialysis procedure, decreased renal function, volume overload, comorbidity and intercurrent clinical events. As the prevalence of inflammation varies considerably between continents and races, dietary and/or genetic factors may have an impact on inflammation in ESRD. Elevated CRP in dialysis patients could be evaluated at three different levels: (i) national/regional level; (ii) dialysis unit level; and (iii) individual patient level.

Associations between renal function, volume status and endotoxaemia in chronic kidney disease patients

Inflammation is an important predictor of increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD), but the mechanisms behind the chronic activation of the immune system are not clearly understood. CKD patients develop fluid overload, which has been proposed to be a stimulus for inflammatory activation due to the translocation of macromolecules from the gut. We hypothesize that fluid overload is associated with signs of systemic inflammation and endotoxaemia in stages 1-5 CKD patients. The aim of this prospective study was to evaluate the associations between renal function, fluid status [evaluated by the inferior vena cava diameter (IVCD) and the collapsibility index (CI)], systemic inflammation [plasma levels of C-reactive protein (CRP), fibrinogen and albumin] and endotoxaemia (through the Limulus amebocyte lysate enzymatic assay) in a group of CKD patients in our out-patient clinic. The population consisted of 74 (mean of 57; range 23-83 years of age; 47% males) CKD patients with glomerular filtration rate (based on the mean of urea and creatinine clearances) of 34 ml/min. Both albumin (Rho = 0.25; P = 0.05) and fibrinogen (Rho= - 0.48; P < 0.0001) were significantly correlated to glomerular filtration rate (GFR). According to the IVCD, 84% of the patients were fluid overloaded, while 83% were considered overloaded by the CI. Signs of endotoxaemia were detected in all patients. Endotoxin levels were higher in patients with signs of fluid overload (0.85 +/- 0.11ng/l) when compared with patients with normal values of IVCD (0.61 +/- 0.05 ng/l; P < 0.05). Endotoxin levels correlated to both IVCD (Rho=0.33, P < 0.005) and CI (Rho = -0.25, P < 0.05). There was no correlation between endotoxin levels and GFR, CRP or fibrinogen. In summary, although most CKD patients presented signs of fluid overload that was associated with endotoxaemia, there was no association between endotoxaemia and systemic inflammation, suggesting the endotoxaemia may not be the main determinant of the inflammatory status in this group of patients.

Nitric oxide and superoxide in rat mesangial cells: modulation by C-reactive protein

BACKGROUND

C-reactive protein (CRP) has been linked to cardiovascular and renal disease. We evaluated the effects of CRP on the production of nitric oxide (NO) and superoxide by rat mesangial cells (RMC) and the impact on cell function.

METHODS AND RESULTS

RMC were incubated with cytokines (IFN-gamma, IL-1beta, and LPS) and CRP (10-100 microg/ml) for 24-72 h. Exposure to CRP resulted in a time- and dose-dependent reduction in NO accumulation (p<0.05). Although inducible nitric oxide synthase (iNOS) protein expression was unaltered after 48 h, CRP stimulated expression of HSP90. Steady state abundance of iNOS mRNA increased nearly threefold after a 24-h exposure to CRP. Incubation with 100 microg/ml CRP for 60-120 min resulted in a 272% increase in superoxide production that was prevented by diphenyleneiodium chloride but not L-NAME (p<0.0001).

CONCLUSION

CRP enhances superoxide release in RMC, which in turn inactivates NO and reduces net production. The functional relevance of these CRP-induced changes is supported by increased expression of HSP90 in RMC exposed to the mediator. These findings suggest that systemic inflammation, which contributes to the pathogenesis of atherosclerosis, may play a role in the progression of kidney disease.

Biomarkers in chronic kidney disease: utility and issues towards better understanding

PURPOSE OF REVIEW

Biomarkers are substances that reflect the presence of a given disease, its pathophysiology or organ damage. These indicators are increasingly proposed to assess prognosis or the response to treatment. This review examines the value of a series of biomarkers which have been recently tested in prospective studies in chronic kidney disease and end-stage renal disease patients.

RECENT FINDINGS

C reactive protein has coherently emerged as an early marker of renal dysfunction. The usefulness of this measurement for predicting the evolution of chronic kidney disease or for monitoring the response to renoprotective treatment, however, still remains unproven. On the other hand the measurement of C reactive protein can be recommended for monitoring the risk of atherosclerotic complications in patients with chronic kidney disease and end-stage renal disease, particularly in those with evidence of coronary heart disease or other cardiovascular complications (i.e. in the vast majority of patients followed up in nephrology clinics). There is growing interest in homocysteine and asymmetric dimethyl arginine as biomarkers of cardiovascular and renal risk but the usefulness of these biomarkers in clinical practice remains to be proven. Brain natriuretic peptide and troponin T are strongly related to cardiovascular outcomes in end-stage renal disease patients but their value in this population still requires to be proper tested in specifically designed intervention studies.

SUMMARY

Among emerging biomarkers C reactive protein is the only one which is very near to fulfilling the methodological requirements for being recommended in clinical practice.

Periodontal disease is associated with renal insufficiency in the Atherosclerosis Risk In Communities (ARIC) study

BACKGROUND

Periodontitis, a chronic bacterial infection of the oral cavity, is a novel risk factor for atherosclerotic cardiovascular disease (CVD). Given the numerous shared risk factors for CVD and chronic kidney disease (CKD), we hypothesized that periodontitis also is associated with renal insufficiency in the Dental Atherosclerosis Risk in Communities study.

METHODS

We conducted a cross-sectional study of 5,537 middle-aged black and white men and women. Periodontitis was determined by using an independent clinically derived definition and categorized as healthy/gingivitis, initial, and severe. Renal insufficiency is defined as glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 . Multivariable logistic regression models were used to estimate odds ratios and 95% confidence intervals for renal insufficiency using healthy/gingivitis as the referent group.

RESULTS

A total of 2,276 individuals had initial periodontitis, and 947 individuals had severe periodontal disease. One hundred ten individuals (2%) had a GFR less than 60 mL/min/1.73 m2 . Compared with healthy/gingivitis, initial and severe periodontal disease were associated with a GFR less than 60 mL/min/1.73 m2 (odds ratio, 2.00; 95% confidence interval, 1.23 to 3.24) for initial periodontal disease and an odds ratio of 2.14 for severe disease (95% confidence interval, 1.19 to 3.85) after adjustment for important risk factors for CVD and CKD. Sensitivity analysis showed that initial and severe periodontitis were each associated with an elevated serum creatinine level (men, >1.4 mg/dL [>124 micromol/L]; women, >1.2 mg/dL [>106 micromol/L]; odds ratio, 3.21; 95% confidence interval, 1.32 to 7.76 and odds ratio, 5.39; 95% confidence interval, 2.08 to 13.99, respectively).

CONCLUSION

This is the first study to show an association of periodontal disease with prevalent renal insufficiency. A prospective study is necessary to determine the exact nature of the observed relationship.

Biomarkers of inflammation and progression of chronic kidney disease

BACKGROUND

Chronic kidney disease is associated with higher levels of inflammatory biomarkers. Statins have anti-inflammatory properties and may attenuate loss of kidney function. Although inflammation may mediate progressive renal injury, the relation between statin use, markers of inflammation, and the rate of kidney function loss has not been elucidated. We examined the association between pravastatin use, levels of C-reactive protein (CRP), soluble tumor necrosis factor receptor II (sTNFrii), and the rate of kidney function loss.

METHODS

We performed a post hoc analysis of data from a randomized placebo controlled trial of pravastatin 40 mg daily in people with previous myocardial infarction. Glomerular filtration rate (GFR) was estimated using the Modification of Diet in Renal Disease Study (MDRD) GFR equation. We studied 687 subjects with chronic kidney disease (GFR < 60 mL/min/1.73 m(2)) who did not experience a cardiovascular event during follow-up. Multivariate linear regression was used to study the relation between baseline CRP and sTNFrii and the rate of kidney function loss in mL/min/1.73 m(2)/year. Cross-product interaction terms were used to determine if these relations varied with pravastatin use.

RESULTS

Median baseline GFR was 54.5 mL/min/1.73 m(2) (interquartile range 49.7, 57.8) and median duration of follow-up was 58 months. Higher baseline CRP level was independently associated with more rapid kidney function loss (highest tertile 0.6 mL/min/1.73 m(2) per year faster than lowest tertile) (P= 0.001). A similar independent relation was observed between tertile of sTNFrii and rate of kidney function loss (highest tertile 0.5 mL/min/1.73 m(2) per year faster than lowest tertile) (P= 0.006). Subjects with both CRP and sTNFrii in the highest tertile ("inflamed" status) appeared to derive more renal benefit from pravastatin than those without (P for interaction 0.047). In these 108 subjects, renal function loss in pravastatin recipients was 0.8 mL/min/1.73 m(2)/year slower than placebo (95% CI 0 to 1.5 mL/min/1.73 m(2)/year slower) (P= 0.039).

CONCLUSION

Higher CRP and sTNFrii are independently associated with faster rates of kidney function loss in chronic kidney disease. Pravastatin appears to prevent loss of kidney function to a greater extent in individuals with greater evidence of inflammation, although this was of borderline significance. These data suggest that inflammation may mediate the loss of kidney function among subjects with chronic kidney disease and concomitant coronary disease.

C-reactive protein induces NF-kappaB activation through intracellular calcium and ROS in human mesangial cells

BACKGROUND

C-reactive protein (CRP) is known to have a direct proinflammatory effect in endothelial cells. However, little is known about the effect of CRP in intrinsic renal cells. We investigated the effects of CRP on the nuclear factor-kappaB (NF-kappaB) activation and monocyte chemoattractant protein-1 (MCP-1) gene expression in human mesangial cells and also examined whether intracellular calcium and reactive oxygen species (ROS) were involved in the CRP- induced NF-kappaB activation.

METHODS

NF-kappaB binding activity and MCP-1 mRNA expression were measured by electrophoretic mobility shift assay and Northern blot analysis, respectively. Intracellular calcium was monitored by confocal microscopy using calcium sensitive dye, Fluo-3 and intracellular ROS production was determined, using 2',7'-dichlorofluorescin diacetate.

RESULTS

CRP increased NF-kappaB binding activity in a dose-dependent manner (12.5-100 microg/ml), which was induced within 1 h after incubation and peaked around 3 h. CRP also increased the MCP-1 mRNA expression via activation of NF-kappaB. Both intracellular calcium and ROS was induced by CRP. Calcium chelator, BAPTA-AM and anti-oxidants such as N-acetylcysteine and tiron suppressed CRP-induced NF-kappaB activation.

CONCLUSION

CRP exerted a proinflammatory effect in human mesangial cells by inducing MCP-1 gene expression via NF-kappaB activation, which was mediated, at least in part, through intracellular calcium and ROS.

Serum C-reactive Protein Level Is Associated with Renal Function and It Affects Echocardiographic Cardiovascular Disease in Pre-Dialysis Patients

BACKGROUND

Relevance of serum CRP for morbidity and mortality in pre-dialysis patients has not been assessed extensively. The aim of this study was to determine the incidence of elevated serum CRP in pre-dialysis patients and to identify the factors that associate with serum CRP. We were also evaluated the effects of serum CRP on cardiovascular disease, anemia, and nutritional markers.

METHODS

One hundred and eight pre-dialysis patients with a mean creatinine clearance (CrCl) of 30.1 ml/min were included in the study. Data collected from each patient included demographics, co-morbidity, medications, blood pressures, blood biochemistry including serum CRP, renal function, and echocardiography.

RESULTS

Serum CRP was elevated (>5 mg/l) in 43 patients (39.8%). There was a negative correlation between serum CRP and CrCl (r = -0.370, p < 0.001). CrCl was the unique independent factor affecting serum CRP. Serum CRP was an independent factor affecting left ventricular mass index, fractional shortening, serum albumin and hematocrit in multivariate analyses.

CONCLUSIONS

Prevalence of elevated serum CRP in pre-dialysis patients is high. Reduced renal clearance of CRP and/or cytokines may contribute to the inflammatory status. Elevated serum CRP is an important cause of morbidity in pre-dialysis patients.