The effect of renal transplantation on adiponectin and its isoforms and receptors

Combined donor-recipient genotypes of leptin receptor and adiponectin gene polymorphisms affect the incidence of complications after renal transplantation

BACKGROUND

We aimed to examine whether combined donor/recipient variants in the leptin receptor (LEPR) and adiponectin (ADIPOQ) genes may affect outcomes in renal transplantation.

METHODS

A total of 233 donors and their corresponding 307 recipients were genotyped for LEPR rs1805094, rs1137100 and rs1137101, and ADIPOQ rs1501299 and rs224176. Combined donor/recipient genetic scores were created to investigate associations with delayed graft function (DGF), graft loss and estimated glomerular filtration rate (eGFR).

RESULTS

Recipients whose donors carried variant alleles of LEPR rs1137100 and rs1137101 had lower risk of DGF [OR = 0.48 (0.24-0.97), p = 0.040] and [OR = 0.47 (0.23-0.95), p = 0.035], respectively. In addition, rs1137101 also showed an inverse association with lower incidence of graft loss [OR = 0.44 (0.31-0.97), p = 0.040]. The analysis of genetic scores of donor/recipients showed that again rs1137101 was inversely associated with both outcomes: OR = 0.46 (0.23-0.92), p = 0.029 and OR = 0.45 (0.11-0.81), p = 0.009, respectively. With regard to graft function, the T-allele of ADIPOQ rs1501299 in the donor was related to higher eGFR values (75.26 ± 29.01 vs. 67.34 ± 25.39 ml/min for wild-type grafts, p = 0.012). Higher combined genetic scores in this same polymorphism were also associated with better function (78.33 ± 31.87 vs. 68.25 ± 24.32 ml/min, p = 0.018). Finally, eGFR values were similar between paired kidneys but they were different when comparing grafts with or without the rs1501299 T-variant (77.87 ± 26.50 vs. 69.27 ± 26.73 ml/min, p = 0.016).

CONCLUSIONS

Our study has shown for the first time to our knowledge that variants in LEPR and ADIPOQ genes of the donors and/or their combination with those in the recipients may affect the outcome of renal transplantation.

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.

Adiponectin signaling and its role in bone metabolism

Adiponectin, the most prevalent adipo-cytokine in plasma plays critical metabolic and anti-inflammatory roles is fast emerging as an important molecular target for the treatment of metabolic disorders. Adiponectin action is critical in multiple organs including cardio-vascular system, muscle, liver, adipose tissue, brain and bone. Adiponectin signaling in bone has been a topic of active investigation lately. Human association studies and multiple mice models of gene deletion/modification failed to define a clear cause and effect of adiponectin signaling in bone. The most plausible reason could be the multimeric forms of adiponectin that display differential binding to receptors (adipoR1 and adipoR2) with cell-specific receptor variants in bone. Discovery of small molecule agonist of adipoR1 suggested a salutary role of this receptor in bone metabolism. The downstream signaling of adipoR1 in osteoblasts involves stimulation of oxidative phosphorylation leading to increased differentiation via the likely suppression of wnt inhibitor, sclerostin. On the other hand, the inflammation modulatory effect of adiponectin signaling suppresses the RANKL (receptor activator of nuclear factor κ-B ligand) - to - OPG (osteprotegerin) ratio in osteoblasts leading to the suppression of osteoclastogenic response. This review will discuss the adiponectin signaling and its role in skeletal homeostasis and critically assess whether adipoR1 could be a therapeutic target for the treatment of metabolic bone diseases.

Adiponectin and Its Isoforms in Pathophysiology

Adiponectin circulates in blood in multiple isoforms. High molecular weight (HMW) adiponectin is thought to be most biologically active and promotes glucose uptake, insulin sensitivity, and fatty acid oxidation. In obesity, adiponectin isoform formation is disrupted, leading to an inverse association between metabolic disease and HMW and total adiponectin. Adiponectin isoforms also function as acute-phase reactants influencing inflammation in acute and chronic disease. Interestingly, adiponectin and mortality have a U-shaped association. Unfortunately, data concerning adiponectin and its pathophysiologic function conflict. This is predominantly due to difficulties in adequate measurement of adiponectin isoforms and lack of a gold standard. In this review we provide a general overview of the formation and function of adiponectin and its isoforms under physiologic conditions. We highlight the ways adiponectin isoform formation is disrupted in obesity and its ensuing pathologic conditions. Furthermore, we will elaborate on the role of adiponectin isoforms as inflammatory proteins with respect to cardiac and kidney disease and discuss the association of adiponectin with mortality. Finally, we will provide a historical perspective on the measurement of adiponectin isoforms, current limitations, and future challenges.

Adiponectin Fractions Influence the Development of Posttransplant Diabetes Mellitus and Cardiovascular Disease in Japanese Renal Transplant Recipients

Background

A few studies have investigated the role of adiponectin fraction for cardiovascular disease (CVD) in RTx recipients.

Subjects and Methods

We studied 57 adult subjects (39 males, 18 females; 10 cadaveric donors) with at least three years of allograft survival (median 251 months). We examined clinical backgrounds such as treated drugs, blood pressure (BP, mmHg), body mass index (BMI), and blood chemistry including cholesterol (total, LDL-C, HDL-C), glucose, glycated hemoglobin (HbA1c), and serum high and low-molecular-weight (HMW/LMW) ADPN fractions with regard to the associations of the visceral and subcutaneous fat areas on CT scan. We also analyzed the associations of CVD and post-transplant diabetes (PTDM) with ADPN fractions and the fat areas.

Results

The visceral fat area was inversely correlated with serum HMW and LMW ADPN levels and HMW ADPN ratio (r = -0.400, p = 0.002 and r = -0.296, p = 0.025 and r = -0.444, p<0.001, respectively). Furthermore, the visceral fat area was positively with the LMW ADPN ratio (r = 0.467, p<0.001), but no significant correlation was noted between the subcutaneous fat area and the ADPN ratio. On multiple regression analysis, eGFR and the visceral fat area were significant reducing factors of HMW ADPN levels, and the alteration of eGFR was identified as an increasing factor of HMW ADPN levels. Patients with CVD had larger visceral fat area (p = 0.004), lower HMW ADPN ratio (p = 0.022) and higher LMW ADPN ratio (p = 0.049). In addition, the higher HMW ADPN ratio and statin treatment were identified as reducing factors of the development of CVD, but the LDL-C level was an aggravating factor. Moreover, the higher LMW ADPN ratio and the visceral fat area were aggravating factors of PTDM.

Conclusion

Even in Japanese renal transplant recipients, visceral fat area and ADPN fractions were significant factors for the development of both CVD and PTDM.

Adipocytokines in renal transplant recipients

In the last two decades, perceptions about the role of body fat have changed. Adipocytes modulate endocrine and immune homeostasis by synthesizing hundreds of hormones, known as adipocytokines. Many studies have been investigating the influences and effects of these adipocytokines and suggest that they are modulated by the nutritional and immunologic milieu. Kidney transplant recipients (KTRs) are a unique and relevant population in which the function of adipocytokines can be examined, given their altered nutritional and immune status and subsequent dysregulation of adipocytokine metabolism. In this review, we summarize the recent findings about four specific adipocytokines and their respective roles in KTRs. We decided to evaluate the most widely described adipocytokines, including leptin, adiponectin, visfatin and resistin. Increasing evidence suggests that these adipocytokines may lead to cardiovascular events and metabolic changes in the general population and may also increase mortality and graft loss rate in KTRs. In addition, we present findings on the interrelationship between serum adipocytokine levels and nutritional and immunologic status, and mechanisms by which adipocytokines modulate morbidity and outcomes in KTRs.

Association of Adiponectin With Body Composition and Mortality in Hemodialysis Patients

BACKGROUND

In the general population, circulating adiponectin is associated with a favorable cardiovascular risk profile (eg, lower triglycerides and body fat) and decreased mortality. Hemodialysis (HD) patients have comparatively higher adiponectin concentrations, but prior studies examining the adiponectin-mortality association in this population have not accounted for body composition or shown a consistent relationship.

STUDY DESIGN

Prospective cohort study.

SETTINGS & PARTICIPANTS

We examined baseline serum adiponectin concentrations in 501 HD patients across 13 dialysis centers from the prospective MADRAD (Malnutrition, Diet, and Racial Disparities in Chronic Kidney Disease) cohort (entry period, October 2011 to February 2013; follow-up through August 2013).

PREDICTOR

Serum adiponectin concentration in tertiles (tertiles 1, 2, and 3 defined as ≤16.1, >16.1-<30.1, and ≥30.1-100.0 μg/mL, respectively). Adjustment variables included case-mix and laboratory test results (age, sex, race, ethnicity, vintage, diabetes, serum albumin, total iron-binding capacity, serum creatinine, white blood cell count, phosphate, hemoglobin, and normalized protein catabolic rate), body composition surrogates (subcutaneous, visceral, and total-body fat and lean body mass), and serum lipid levels (cholesterol, high-density lipoprotein cholesterol, and triglycerides).

OUTCOMES

All-cause mortality using survival (Cox) models incrementally adjusted for case-mix and laboratory test results.

RESULTS

Among 501 HD patients, 50 deaths were observed during 631.1 person-years of follow-up. In case-mix- and laboratory-adjusted Cox analyses, the highest adiponectin tertile was associated with increased mortality versus the lowest tertile (HR, 3.35; 95% CI, 1.50-7.47). These associations were robust in analyses that additionally accounted for body composition (HR, 3.18; 95% CI, 1.61-8.24) and lipid levels (HR, 3.64; 95% CI, 1.34-7.58).

LIMITATIONS

Residual confounding cannot be excluded.

CONCLUSIONS

Higher adiponectin level is associated with a 3-fold higher death risk in HD patients independent of body composition and lipid levels. Future studies are needed to elucidate underlying mechanisms and determine therapeutic targets associated with improved outcomes in HD patients.

Adipokines protecting CKD

Increasing incidence of chronic kidney disease (CKD) which leads to end-stage renal disease (ESRD) is one of the major health issues in the modern world and requires novel strategies for treatment. Adipose tissue has been recognized to have endocrine function and secretes a variety of hormones called adipokines. Several adipokines have been implicated in the pathogenesis of CKD and may have a strong impact as a risk factor for renal decline. The aim of this review is to provide an overview of the role of adipokines in the progression of CKD, with focus on recent experimental and clinical advances.

Adiponectin receptor and adiponectin signaling in human tissue among patients with end-stage renal disease

BACKGROUND

Adiponectin plasma levels in chronic kidney disease (CKD) are two to three times higher than in individuals with normal kidney function. Despite adiponectin's anti-diabetic, anti-inflammatory and anti-atherogenic properties, patients with CKD have insulin resistance, systemic inflammation and accelerated atherogenesis. Hence, although adiponectin production is increased by adipose tissue in end-stage renal disease (ESRD), it is unclear if its effects on metabolism remain intact.

METHODS

To determine if there is adiponectin resistance in ESRD, we measured tissue levels of adiponectin receptor-1 (AdipoR1) and adiponectin downstream effectors in ESRD patients compared with normal kidney function controls. Blood and tissue samples were obtained from participants at the time of kidney transplantation or kidney donation. A follow-up blood sample was obtained 3-6 months after transplantation.

RESULTS

AdipoR1 was higher in muscle and peripheral blood mononuclear cells collected from ESRD patients. There was also a nonsignificant increase in AdipoR1 in visceral fat of ESRD compared with controls. Compared with controls, phosphorylation of the adiponectin downstream effector adenosine monophosphate-activated protein kinase (AMPK) was higher in ESRD while acetyl-CoA carboxylase phosphorylation (ACC-P) and carnitine palmitoyl transferase-1 (CPT-1) levels were lower. In vitro, exposure of C2C12 cells to uremic serum resulted in upregulation of AdipoR1 and increased phosphorylation of AMPK but decreased ACC-P and CPT-1 expression.

CONCLUSION

Both our in vivo and in vitro observations indicate that uremia results in upregulation of AdipoR1 but adiponectin resistance at the post-receptor level.

Urinary adiponectin excretion rises with increasing albuminuria in type 1 diabetes

AIM

Urinary adiponectin (u-adiponectin) excretion has been suggested to reflect early glomerular damage. Inspired by this, we studied the levels of u-adiponectin in type 1 diabetic patients with different levels of urinary albumin excretion (UAE).

METHODS

U-adiponectin was analysed by ELISA in type 1 diabetic patients: Fifty-eight with normoalbuminuria (<30mg albumin/24h), 43 with persistent microalbuminuria (30-300mg/24h) and 44 with persistent macroalbuminuria (>300mg/24h). For comparison, a control group of 55 healthy individuals was included.

RESULTS

U-adiponectin increased with increasing levels of UAE (p<0.01). U-adiponectin median (interquartile range): Normoalbuminuria 0.38 (0.14-1.31), microalbuminuria 1.12 (0.20-2.68), macroalbuminuria 9.20 (1.10-23.35) and controls 0.09 (0.06-0.24) μg/g creatinine. Levels were unrelated to sex, age, cholesterol, diastolic BP and BMI. U-adiponectin was weakly associated with increasing systolic BP and HbA1c (r(2)<0.1, p<0.05), but strongly related to increasing UAE (r(2)=0.57, p<0.001) and decreasing eGFR (r(2)=0.26, p<0.001). The relationship between UAE and u-adiponectin was significant in all groups and independent of eGFR, BMI, BP and HbA1c. Furthermore, u-adiponectin was associated with markers of tubular damage (p<0.01).

CONCLUSION

U-adiponectin rises with increasing levels of UAE in patients with type 1 diabetes. This is in accordance with the hypothesis that loss of adiponectin may reflect glomerular and/or tubular damage.

The adipose tissue as an endocrine organ

During the past 2 decades, results of both basic science and clinical studies have changed the physicians' views about adipocyte pathophysiology. Since leptin was discovered in 1994, white adipose tissue was recognized as an endocrine organ and an important source of biologically active substances with local and/or systemic action called adipokines. Inappropriate secretion of several adipokines by the excessive amount of white adipose tissue seems to participate in the pathogenesis of obesity-related pathologic processes including endothelial dysfunction, inflammation, atherosclerosis, diabetes mellitus, and chronic kidney disease. In this review endocrine action of selected adipokines (mainly leptin and adiponectin) in the context of kidney diseases is discussed. Specifically, the role of these adipokines in malnutrition, chronic kidney disease progression, and pathogenesis of cardiovascular complications is presented.

The adipose tissue production of adiponectin is increased in end-stage renal disease

Adiponectin has anti-diabetic properties and patients with obesity, diabetes and insulin resistance have low plasma adiponectin levels. However, although kidney disease is associated with insulin resistance, adiponectin is elevated in end stage renal disease. Here we determine if adipose tissue production of adiponectin is increased in renal disease in a case-control study of 36 patients with end stage renal disease and 23 kidney donors. Blood and tissue samples were obtained at kidney transplantation and donation. The mean plasma adiponectin level was significantly increased to 15.6 mg/ml in cases compared to 8.4 mg/ml in controls. Plasma levels of the inflammatory adipokines tumor necrosis factor α, interleukin 6 and high sensitivity C-reactive protein were significantly higher in cases compared to controls. Adiponectin mRNA and protein expression in visceral and subcutaneous fat was significantly higher in cases than controls while adiponectin receptor 1 mRNA expression was significantly increased in peripheral blood cells, muscle and adipose tissue in cases compared to controls. Thus, our study suggests that adipose tissue production of adiponectin contributes to the high plasma levels seen in end stage renal disease.

Adiponectin in renal disease--a review of the evidence as a risk factor for cardiovascular and all-cause mortality

Adiponectin, an adipokine, was discovered in 1995. The initial evidence led to the study of adiponectin as a determinant of insulin sensitivity and blood glucose levels. The literature then evolved to reports of the inverse association of adiponectin with incident Type 2 diabetes mellitus and coronary heart disease. Shortly thereafter, reports of a positive association with heart failure and mortality appeared and were replicated. We review here the basic science evidence and clinical studies of the role of renal function and kidney disease as a determinant of adiponectin.

Plasma adiponectin before and after kidney transplantation

The role of plasma adiponectin (ADPN) in patients with impaired kidney function and following kidney transplantation (Tx) is debated. We aimed to: (i) determine whether pretransplant ADPN level is an independent risk factor for deterioration of glucose tolerance including development of new-onset diabetes mellitus after Tx, (ii) describe which parameters that influence the ADPN concentration before and after Tx. Fifty-seven nondiabetic kidney allograft recipients and 40 nondiabetic uraemic patients were included. The Tx group was examined at baseline and 3 and 12 months after Tx. The uraemic control group was examined twice, separated by 12 months. ADPN levels declined significantly following Tx (P < 0.0001), while estimated glomerular filtration rate (eGFR) increased (P < 0.0005). eGFR, BMI and insulin sensitivity index were independently associated with ADPN in a multivariate regression analysis, whereas an ordinal logistic regression analysis revealed no predictive characteristic of ADPN for aggravation of the glucose tolerance after Tx. In conclusion, kidney transplantation is accompanied by a significant reduction in ADPN concentration. Several factors determine the ADPN concentration before and after Tx including kidney function, insulin resistance, use of immunosuppressive agents and BMI. Pretransplant ADPN level did not predict development of new-onset diabetes mellitus or even deterioration of the glucose tolerance following Tx.

Lower total and percent of high-molecular-weight adiponectin concentration in South Asian kidney transplant recipients

BACKGROUND

Ethnicity is an important determinant of post-renal transplant outcomes. Limited data are available on cardiovascular risk differences in kidney transplant recipients (KTR) based on ethnicity.

METHODS

A group of 129 clinically stable age-matched KTR [43 South Asian (SA), 86 Caucasian]) were assessed for plasma total and high-molecular-weight (HMW) adiponectin, cystatin C, apolipoproteins A1 and B, C-reactive protein, uric acid, urine albumin-to-creatinine ratio, estimated glomerular filtration rate (eGFR) and transplant-specific plus traditional Framingham risk factors. SA and Caucasians were compared by t-tests, Wilcoxon rank-sum or chi-square testing. Accounting for the matched design, multivariable linear regression was performed to determine predictors of adiponectin concentrations.

RESULTS

SA did not differ from Caucasians in background cardiac disease or cardioprotective medication use or risk factors other than smoking (26 versus 56%, P = 0.001). Total adiponectin (9.5 ± 3.5 versus 12.9 ± 6.7 μmg/mL, P < 0.001) and HMW adiponectin (22 ± 9 versus 29 ± 11%, P < 0.001) were significantly lower in SA. Determinants of total adiponectin included SA ethnicity (P = 0.02), cystatin C-eGFR (P < 0.001), high-density lipoprotein (HDL) cholesterol (P < 0.0001) and waist-to-hip ratio (P < 0.001), while those of HMW adiponectin included SA ethnicity (P < 0.001), cystatin C-eGFR (P = 0.03) and HDL cholesterol (P = 0.001). There were no important differences in the other measured biomarkers.

CONCLUSION

Total and HMW adiponectin concentrations are lower in SA KTR and may be promising exploratory biomarkers of post-transplant cardiovascular risk.

High serum adiponectin concentration in children with chronic kidney disease

Adiponectin (ADPN) counteracts the inflammatory response of the endothelium, which plays an important role in the development of atherosclerosis in patients with chronic kidney disease (CKD). Data in children with CKD are scarce. We examined serum ADPN concentration in 90 children with various renal disorders: 28 with CKD on conservative treatment (CKD), 21 on regular dialysis treatment (D), and 41 after kidney transplantation (Tx); 27 age-matched healthy children served as controls (C). Body mass index (BMI), estimated glomerular filtration rate (eGFR), lipids, homocysteine, high sensitivity CRP (hsCRP), and systolic blood pressure (SBP) were also measured. Mean serum ADPN concentration was significantly higher in patients with CKD (27.3 μg/ml ±15.0), on D (34.2 μg/ml ±14.9), and after Tx (23.6 μg/ml ±9.5) compared with ADPN levels in C (13.5 μg/ml ±6.1) (p < 0.0001). Serum ADPN concentration was inversely related to BMI (p = 0.001) and SBP (p = 0.004). In the multiple linear regression analysis, only SBP remained independently associated with ADPN plasma levels. Data show that children with CKD have significantly higher serum ADPN, even after Tx. The protective antiarthrosclerotic effect of ADPN may be mediated by lower SBP, a finding that deserves further study.

Clinical review: adiponectin biology and its role in inflammation and critical illness

Adiponectin is an adipokine first described just over a decade ago. Produced almost exclusively by adipocytes, adiponectin circulates in high concentrations in human plasma. Research into this hormone has revealed it to have insulin-sensitizing, anti-inflammatory and cardioprotective roles. This review discusses the history, biology and physiological role of adiponectin and explores its role in disease, with specific focus on adiponectin in inflammation and sepsis. It appears that an inverse relationship exists between adiponectin and inflammatory cytokines. Low levels of adiponectin have been found in critically ill patients, although data are limited in human subjects at this stage. The role of adiponectin in systemic inflammation and critical illness is not well defined. Early data suggest that plasma levels of adiponectin are decreased in critical illness. Whether this is a result of the disease process itself or whether patients with lower levels of this hormone are more susceptible to developing a critical illness is not known. This observation of lower adiponectin levels then raises the possibility of therapeutic options to increase circulating adiponectin levels. The various options for modulation of serum adiponectin (recombinant adiponectin, thiazolidinediones) are discussed.

Plasma adiponectin concentration and insulin resistance: role of successful kidney transplantation

Adiponectin (ADPN) has been reported to be inversely correlated with insulin resistance (IR) in uremic subjects and following kidney transplantation. Kidneys have been suggested to play a part in ADPN clearance. This study sought to evaluate this hypothesis. We enrolled 67 candidates with end-stage renal disease (ESRD) along with 30 healthy unrelated donors. Plasma ADPN, IR (based on the homeostasis model assessment for IR index), and glomerular filtration rates were compared between control and patient groups. The correlations of the aforementioned variables were also compared in the patient group 1 day before and 14 days following transplantation. The changes in measured parameters were also compared with control group values. The glomerular filtration rate was significantly decreased among recipients. ADPN levels were remarkably higher in the patient group before transplantation when compared with healthy subjects (P<.001) and remained significantly higher thereafter (P<.001). Insulin resistance was higher, albeit not significantly, among ESRD patients compared with controls (P>.05) and it increased following transplantation (P=.03). There was no correlation between ADPN, IR, and glomerular filtration rate in normal individuals or ESRD patients before or after transplantation. It is our assumption that mechanisms other than kidney function are probably involved in ADPN metabolism in ESRD patients and in the immediate phase following transplantation. It does not seem that ADPN substantially affects IR either in ESRD or transplantation patients.

Adiponectin in patients with chronic kidney disease

Adiponectin is one of many so called "adipokines"--cytokines, chemokines, growth factors, and complement proteins secreted by adipose tissue--that can affect the function of other organs. This antiatherogenic and insulin-sensitizing polypeptide is eliminated from the circulation mostly by the kidneys. Thus, in patients with chronic kidney disease, adiponectin accumulates in the circulation; its plasma concentration is approximately three times higher in end stage kidney disease than in healthy subjects. As no biological consequences of these unusually high adiponectin concentrations have been demonstrated, this polypeptide cannot be considered as a uremic toxin. On the contrary, inadequately low instead of high plasma adiponectin concentration is recognized as a new nontraditional risk factor of cardiovascular morbidity and mortality in these patients. This review summarizes the causes and clinical consequences of adiponectin accumulation in the circulation of patients with chronic kidney disease.

Serum adiponectin levels and ambulatory blood pressure monitoring in pediatric renal transplant recipients

BACKGROUND.: Reduced levels of serum adiponectin, an adipokine, are associated with cardiovascular and obesity-related diseases; however, relations between adiponectin and hypertension are unclear. METHODS.: This cross-sectional study examined adiponectin and ambulatory blood pressure monitoring (ABPM) in 33 pediatric renal transplant recipients (TXP), aged 8 to 19 years, median of 1.9 years after transplant. Serum total adiponectin (microg/mL) and high molecular weight-to-total adiponectin ratio (HMWr), 24-hr ABPM, and dual x-ray absorptiometry measures of fat mass were obtained. RESULTS.: The 12 TXP with hypertension (defined as BP index >1.0 and BP load >25%) had lower total adiponectin levels (7.4+/-3.2 vs. 10.9+/-5.2 microg/mL, P=0.045) compared with nonhypertensive TXP. Hypertensive TXP trended toward lower HMWr compared with nonhypertensive TXP (0.40+/-0.09 vs. 0.47+/-0.11, P=0.064). Levels did not differ according to sex, obesity or dipper status. In univariate analyses, total adiponectin and HMWr were negatively and significantly correlated with indexed BP in the daytime, nighttime, and 24-hr periods (R=-0.35 to -0.57). After adjustment for estimated glomerular filtration rate, fat mass, anti-hypertensive medication and fasting glucose, (1) lower total adiponectin was significantly and independently associated with greater elevations in all ABPM indexes except for nighttime systolic indexed BP, and (2) HMWr was inversely associated with all ABPM indexes. Lower adiponectin levels (P=0.049) and HMWr (P=0.042) were associated with greater odds of hypertension. CONCLUSION.: These data indicate that lower total adiponectin and HMWr were significantly and independently associated with greater ambulatory blood pressure.

Increment and impairment of adiponectin in renal failure

AIMS

Patients with chronic renal failure are at high risk of cardiovascular diseases. Previous studies in healthy population showed that hypoadiponectinemia was associated with high cardiovascular disease risk. However, plasma adiponectin (APN) levels are increased in renal dysfunction. Therefore, the clinical significance of plasma APN level in patients with moderate renal dysfunction is controversial. The aim of this study was to determine the change of plasma APN levels in a mouse model of renal failure and the loss of vasculo-protective function of APN in the presence of high cystatin C levels.

METHODS AND RESULTS

Subtotal (5/6) nephrectomy was performed in APN-knockout (KO) mice and wild-type (WT) mice. The procedure in WT mice resulted in the significant increase of plasma APN and cystatin C levels. The clearance rate of APN was measured by injecting plasma from WT mice into KO mice. The clearance rate was significantly decreased in subtotal nephrectomized KO mice compared with sham-operated KO mice. Adiponectin protein and mRNA levels in adipose tissue were similar to subtotal nephrectomized and sham-operated mice. In cultured endothelial cells, at a high concentration corresponding to renal failure, cystatin C abolished the suppressive effects of APN on tumour necrosis factor alpha-induced expression of monocyte adhesion molecules.

CONCLUSION

Plasma APN increases in chronic renal failure, at least in part due to low clearance rate. High concentrations of cystatin C abolish the vasculo-protective effect of APN.

Insulin resistance and insulin secretion changes in kidney transplant recipients with normal graft function compared with those with delayed graft function early after transplantation

INTRODUCTION

We compared insulin resistance (IR) and insulin secretion (IS) among kidney transplant recipients with normal versus delayed graft function (DGF) early after transplantation.

METHODS

We selected 55 kidney transplant recipients without a history of clinical diabetes mellitus. The basal values of glucose (G) and insulin (I) were used to calculate indices of IR and IS before, on the third day, as well as at the end of the first, second, and third weeks after transplantation.

RESULTS

Before transplantation IR was more prevalent (62.5%) than impaired IS (20%; P = .012). Three weeks after engraftment, IR was significantly reduced (P < .001), whereas the reduction in the IS was not significant (P = .17). Splitting the results between normal and delayed functioning grafts showed a significant difference in both IR and IS between the 2 groups on the third day after transplantation (P = .018 and .024, respectively). Regression models showed that only cumulative administered cyclosporine dose and plasma creatinine were significantly (or near significantly) associated with IR (P = .04 and .07, respectively).

CONCLUSION

Among patients with DGF there was a significantly greater prevalence of IR and IS compared with successfully engrafted patients in the middle of the first week after transplantation. With resumption of normal kidney function among the DGF group, this difference disappeared at the end of the third week after transplantation.

Adiponectin: good, bad, or just plain ugly?

It has been suggested that adiponectin has antiatherogenic, anti-inflammatory, and insulin-sensitizing properties. However, studies in humans have reported inverse as well as positive associations between adiponectin concentrations and disease states. This Commentary discusses the apparent conflict in the literature.

The impact of new-onset diabetes on arterial stiffness after renal transplantation

New-onset diabetes after renal transplantation (NODAT) is known to be a potent risk factor for cardiovascular events. We therefore investigated the incidence and risk factors for NODAT, and evaluated surrogate endpoints of atherosclerosis in Japanese patients with stable renal function after renal transplantation. Seventy-nine patients were enrolled in the study, and a 75 g oral glucose tolerance test (OGTT) was performed in subjects excluding patients with known NODAT. We evaluated the risk factors for NODAT and the degree of atherosclerosis, determined by brachial-ankle pulse wave velocity (baPWV), ankle-brachial blood pressure index (ABPI) and intima-media thickness (IMT) of the carotid artery. Eleven patients diagnosed as NODAT had significantly higher fasting plasma glucose before transplantation, blood pressure, and incidence of hepatitis C virus (HCV) infection than patients without NODAT. Multivariate regression analysis revealed that the independent determinant of NODAT was fasting plasma glucose pre-transplantation, HCV infection and systolic blood pressure. The baPWV in patients with NODAT was significantly higher compared to that in patients without NODAT. In addition, the independent determinant of baPWV evaluated by multivariate regression analysis was an increase in systolic blood pressure and age, and a decrease of adiponectin levels. In conclusion, we found that high fasting plasma glucose prior to transplantation, HCV infection and high blood pressure are risk factors for NODAT in Japanese patients after renal transplantation. Since NODAT patients have advanced arterial stiffness probably due to high blood pressure, strict control of blood pressure will be important for preventing the development of cardiovascular disease in NODAT.