Plasma adiponectin before and after kidney transplantation

Kidney transplantation: is it a solution to endothelial dysfunction?

BACKGROUND

Endothelial dysfunction is associated with elevated cardiovascular risk in patients with end-stage renal disease (ESRD). Kidney transplantation has demonstrated significant ability in reducing mortality and improving quality of life in recipients. Recent studies have also reported improvements in endothelial function following kidney transplantation; however, current literature is limited.

METHODS

We performed a systematic review of PubMed/Medline, Web of Science, Scopus, Cochrane Library, and CINAHL databases for prospective cohort studies that assessed endothelial function prior to and following kidney transplantation via various clinical markers. Follow-up duration ranged from 1 month to 1 year. A meta-analysis of pooled data was conducted using random-effect models for four key markers: brachial artery flow-mediated dilatation (FMD), high-sensitivity C-reactive protein (hsCRP), nitroglycerin-mediated dilation (NMD), and adiponectin.

RESULTS

We included nine studies in our final analysis with a total of 524 patients. Significant improvement of all four biomarkers was observed after transplantation. The mean difference was 2.81% (95% CI 1.92-3.71, p < 0.00001) for FMD, 17.27 mg/L (95% CI 5.82-28.72, p = 0.003) for hsCRP, 1.05%, (95% CI 0.56-1.54, p < 0.0001) for NMD, and 9.27 µg/mL (95% CI 5.96-12.57, p < 0.00001) for adiponectin.

CONCLUSION

There is an immediate reversal of endothelial dysfunction in ESRD patients who undergo kidney transplantation, which may explain observed improvements in cardiovascular morbidity in transplant recipients. Future longitudinal studies are needed to understand possible re-emergence of endothelial dysfunction in the long-term postoperative period.

Association of polymorphisms in leptin and adiponectin genes with long-term outcomes in renal transplant recipients

The effect of polymorphims in leptin and adiponectin genes on long-term outcomes of renal transplantation is unknown. In 349 renal transplant recipients (RTR), we aimed to determine associations between five SNPs in the leptin receptor (LEPR) and adiponectin (ADIPOQ) genes and these outcomes. Follow-up time ranged from 2 to 25 years (mean 10.29 ± 5.16 years). Two SNPs showed associations with long-term outcomes and their statistical significance greatly increased after 39 RTR with a history of cardiovascular events prior to transplantation were removed from the analysis. Adjusted odds ratios (OR) for LEPR rs1805094 and ADIPOQ rs1501299 and risk of graft loss were 0.35 (0.16-0.74) p = 0.006 and 2.37 (1.28-4.37) p = 0.006, respectively. The assessment of risk for global mortality revealed OR values of 0.20 (0.06-0.62), p = 0.005, and 2.43 (1.08-5.44), p = 0.031 for LEPR rs1805094 and ADIPOQ rs1501299, respectively. Our results show that polymorphism in genes involved in leptin and adiponectin function modify long-term outcomes in renal transplantation.

Determinants of Left Ventricular Characteristics Assessed by Cardiac Magnetic Resonance Imaging and Cardiovascular Biomarkers Related to Kidney Transplantation

Background:

Cardiac magnetic resonance (CMR) imaging accurately and precisely measures left ventricular (LV) mass and function. Identifying mechanisms by which LV mass change and functional improvement occur in some end-stage kidney disease (ESKD) patients may help to appropriately target kidney transplant (KT) recipients for further investigation and intervention. The concentration of serum adiponectin, a cardiovascular biomarker, increases in cardiac failure, its production being enhanced by B-type natriuretic peptide (BNP), and both serum adiponectin and BNP concentrations decline posttransplantation.

Objective:

We tested the hypothesis that kidney transplantation alters LV characteristics that relate to serum adiponectin concentrations.

Design:

Prospective and observational cohort study.

Setting:

The study was performed at 3 adult kidney transplant and dialysis centers in Ontario, Canada.

Patients:

A total of 82 KT candidate subjects were recruited (39 to the KT group and 43 to the dialysis group). Predialysis patients were excluded.

Measurements:

Subjects underwent CMR with a 1.5-tesla whole-body magnetic resonance scanner using a phased-array cardiac coil and retrospective vectorographic gating. LV mass, LV ejection fraction (LVEF), LV end-systolic volume (LVESV), and LV end-diastolic volume (LVEDV) were measured by CMR pre-KT and again 12 months post-KT (N = 39), or 12 months later if still receiving dialysis (N = 43). LV mass, LVESV, and LVEDV were indexed for height (m^2.7) to calculate left ventricular mass index (LVMI), left ventricular end-systolic volume index (LVESVI), and left ventricular end-diastolic volume index (LVEDVI), respectively. Serum total adiponectin and N-terminal proBNP (NT-proBNP) concentrations were measured at baseline, 3 months, and 12 months.

Methods:

We performed a prospective 1:1 observational study comparing KT candidates with ESKD either receiving a living donor organ (KT group) or waiting for a deceased donor organ (dialysis group).

Results:

Left ventricular mass index change was −1.98 ± 5.5 and −0.36 ± 5.7 g/m^2.7 for KT versus dialysis subjects (P = .44). Left ventricular mass change was associated with systolic blood pressure (SBP) (P = .0008) and average LV mass (P = .0001). Left ventricular ejection fraction did not improve (2.9 ± 6.6 vs 0.7 ± 4.9 %, P = .09), while LVESVI and LVEDVI decreased more post-KT than with continued dialysis (−3.36 ± 5.6 vs −0.22 ± 4.4 mL/m^2.7, P < .01 and −4.9 ± 8.5 vs −0.3 ± 9.2 mL/m^2.7, P = .02). Both adiponectin (−7.1 ± 11.3 vs −0.11 ± 7.9 µg/mL, P < .0001) and NT-proBNP (−3811 ± 8130 vs 1665 ± 20013 pg/mL, P < .0001) declined post-KT. Post-KT adiponectin correlated with NT-proBNP (P = .001), but not estimated glomerular filtration rate (eGFR) (P = .13). Change in adiponectin did not correlate with change in LVEF in the KT group (Spearman ρ = 0.16, P = .31) or dialysis group (Spearman ρ = 0.19, P = .21).

Limitations:

Few biomarkers of cardiac function were measured to fully contextualize their role during changing kidney function. Limited intrapatient biomarker sampling and CMR measurements precluded constructing dose-response curves of biomarkers to LV mass and function. The CMR timing in relation to dialysis was not standardized.

Conclusions:

The LVESVI and LVEDVI but not LVMI or LVEF improve post-KT. LVMI and LVEF change is independent of renal function and adiponectin. As adiponectin correlates with NT-proBNP post-KT, improved renal function through KT restores the normal heart-endocrine axis.

Association of Body Mass Index and the Risk of New-Onset Diabetes After Kidney Transplantation: A Meta-analysis

OBJECTIVE

To comprehensively examine the correlation between body mass index (BMI) and the risk of new-onset diabetes after kidney transplantation (NODAT).

METHODS

The electronic databases Pubmed, Embase, and Cochrane Library, updated in December 2016, were searched, and a literature review was conducted as well to identify relevant research studies. With the use of R 3.12 software, the association between BMI and NODAT risk was analyzed by means of a meta-analysis, with the mean differences (MDs) and their 95% confidence intervals (CIs) as effect indexes. Publication bias was assessed with the use of the Egger test. A sensitivity analysis was performed by excluding 1 study at a time. And the overall morbidity of NODAT was calculated.

RESULTS

In the meta-analysis, 55 eligible studies involving 15,458 kidney transplantation cases were included. After the heterogeneity test, the random-effects model was used to calculate the pooled results of the effect indexes. The results of the meta-analysis showed that BMI was an independent risk factor of NODAT (MD, 1.88; 95% CI, 1.48-2.27). No publication bias was found among the included studies (t = 0.3417; P = 0.7339). The sensitivity analysis revealed that the pooled MD did not reverse after ignoring 1 study at a time. In addition, the overall morbidity of NODAT was 21% (95% CI, 21%-23%).

CONCLUSIONS

Our results suggest that BMI is an independent risk factor for NODAT.

Progranulin serum levels in human kidney transplant recipients: A longitudinal study

BACKGROUND

The adipokine progranulin has metabolic proprieties, playing a role in obesity and insulin resistance. Its levels seems to be dependent of renal function, since higher progranulin concentration is observed in patients with end-stage kidney disease. However, the effect of kidney transplantation on progranulin remains unknown.

OBJECTIVE

To assess the serum progranulin levels in kidney transplant recipients before and after kidney transplantation.

METHODS

Forty-six prospective kidney transplant recipients were included in this longitudinal study. They were evaluated before transplantation and at three and twelve months after transplantation. Clinical, anthropometric and laboratorial measurements were assessed. Progranulin was determined with enzyme-linked immunosorbent assays.

RESULTS

Serum progranulin significantly decreased in the early period after transplantation (from 72.78 ± 2.86 ng/mL before transplantation to 40.65 ± 1.49 ng/mL at three months; p<0.01) and increased at one year (53.15 ± 2.55 ng/mL; p<0.01 vs. three months), remaining significantly lower than before transplantation (p<0.01) (pover time<0.01). At one year after transplantation, there was a significant increase in body mass index, trunk fat and waist circumference compared to immediate period after transplantation. Progranulin was associated with waist circumference and fasting plasma glucose after adjusted for age, gender, study period, glomerular filtration rate, interleukin-6, high sensitivity C reactive protein and adiponectin.

CONCLUSION

Progranulin serum levels are increased before transplantation and a reduction is observed in the early period after transplantation, possibly attributed to an improvement in renal function. At one year after transplantation, an increment in progranulin is observed, seems to be independent of glomerular filtration, and remained significantly lower than before transplantation.

Adiponectin, leptin, nitric oxide, and C-reactive protein levels in kidney transplant recipients: comparison with the hemodialysis and chronic renal failure

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in patients with chronic kidney disease (CKD) including kidney transplant recipients (KTR). Secondary lipid metabolism disorders, endothelial dysfunction, and inflammation enhance the risk of CVD development in these patients. The aim of the present study was to investigate the lipid profile, adiponectin, leptin, nitric oxide (NO), and high sensitivity C-reactive protein (hs-CRP) levels in KTR and to compare these parameters with those of the patients with chronic renal failure (CRF), hemodialysis (HD) patients, and healthy controls.

METHODS

Serum adiponectin and leptin levels were measured by radioimmunoassay; hs-CRP was determined immunoturbidimetrically. Determination of NO was based on the Griess reaction.

RESULTS

Compared with the control group, serum NO and adiponectin levels were significantly higher in the KTR, CRF, and HD groups; hs-CRP levels were significantly higher in the KTR and HD groups; leptin levels were significantly higher in the KTR. In addition, serum NO level was significantly higher in the KTR compared to CRF cases. Adiponectin correlated positively with high density lipoprotein-cholesterol in the control and patient groups. A positive correlation was observed between hs-CRP and NO in the KTR and the patients with CRF. Serum adiponectin levels were inversely correlated with hs-CRP and leptin in the HD group.

CONCLUSION

KTR suffer from inflammation and accompanying changes in levels of adipocytokines and NO which contribute to the increased risk of CVD in these patients.

Effect of Transplant on Platelet Function Markers (P-Selectin and Platelet Aggregation) and Adiponectin in Renal Transplant Patients

OBJECTIVES

In chronic kidney disease, both bleeding and thrombotic complications are observed, although with expected recovery after a successful transplant. Adiponectin has protective properties with respect to atherogenesis and inflammation. Plasma adiponectin levels are markedly elevated among patients with end-stage renal disease and are lower after kidney transplant. However, this topic is still debated in the literature. Here, we evaluated the effect of transplant on platelet function markers (P-selectin and platelet aggregation) and adiponectin in renal transplant patients.

MATERIALS AND METHODS

Our study included 14 renal transplant patients. Preoperative and week 1, month 1, month 6, year 1, and year 2 samples after transplant were studied. In addition to plasma adiponectin, P-selectin levels, and platelet aggregation tests, biochemical tests and coagulation parameters were also studied.

RESULTS

We observed a significant decrease in adiponectin levels 2 years after transplant. Platelet function tests with ADP and collagen were significantly improved, and no changes in P-selectin, ristocetin, and epinephrine levels were observed.

CONCLUSIONS

According to our findings, glomerular filtration rate has an important effect on platelet function, but adiponectin levels became normal only in the second year after transplant. Late improvement of low-density lipoprotein cholesterol and adiponectin after transplant suggested to us that patients with kidney transplant may still have risk of cardiovascular events, especially in the first years.

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 between endothelial and platelet function markers and adiponectin in renal transplanted recipients on cyclosporine and tacrolimus immunosuppression based therapy

AIM

Coagulation abnormalities, endothelial dysfunction and arteriosclerosis play a key role in cardiovascular disease state observed in transplanted patients. Plasma adiponectin levels are lower following kidney transplantation. However, there is still a debate about this topic in the literature. This study evaluated, adiponectin levels associated with markers of endothelial dysfunction and platelet function in renal transplant patients.

METHODS

Sixty-six renal transplant patients were studied. Patients were grouped according to immunosuppression regimen. Group 1 (n = 36) were treated with cyclosporine A based regimes and group 2 (n = 30) were treated with tacrolimus based regimes. Plasma adiponectin, asymmetric dimethyl arginine (ADMA), sP-selectin levels and platelet aggregation tests were studied and were compared with those in control group (n = 15, group 3).

RESULTS

Adiponectin, sP-selectin and ADMA levels were higher in group 1 and statistically significant differences were observed compared with those of group 2 and group 3, respectively (P < 0.001, P < 0.05, P < 0.05). Platelet aggregation values induced by agonists were lower in group 1 than group 2 and group 3, but the difference did not reach statistical significance (P > 0.05).

CONCLUSION

Adiponectin levels are elevated in line with ADMA and sP-selectin levels. Since CsA induces higher adiponectin levels, platelet activation and endothelial dysfunction. These changes may be responsible for the increased risk of post-transplant cardiovascular events in renal transplant patients.

Obesity in kidney disease: A heavyweight opponent

Obesity is an important worldwide challenge that must be faced in most developed and developing countries because of unhealthy nutritional habits. The consequences of obesity and being overweight are observed in different organs, but the kidney is one of the most affected. Excess adipose tissue causes hemodynamic alterations in the kidney that can result in renal disease. However, obesity is also commonly associated with other comorbidities such as chronic inflammation, hypertension and diabetes. This association of several aggravating factors is still a matter of concern in clinical and basic research because the pathophysiologic mechanisms surrounding chronic kidney disease development in obese patients remain unclear. This review will discuss the consequences of obesity in the context of renal injury.

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.

Adiponectin effects on the kidney

Adiponectin is a 30-kDa polypeptide secreted primarily by adipose tissue and plays a key role in kidney disease. In obesity, reduced adiponectin levels are associated with insulin resistance, cardiovascular disease and obesity related kidney disease. The latter includes microalbuminuria, glomerulomegaly, overt proteinuria and focal segmental glomerulosclerosis. Adiponectin levels in type 2 diabetics also negatively correlate with early features of nephropathy. However, in patients with established chronic kidney disease, adiponectin levels are elevated and positively predict progression of disease. The mechanism of action of adiponectin in the kidney appears to be related to AMPK activation and NADPH oxidase. Further studies are needed to elucidate this pathway and investigate the role of potential targets of adiponectin-AMPK-Nox pathway for CKD as obesity-related CKD is increasing worldwide.