Association of Genetic Polymorphisms of Interleukins With New-Onset Diabetes After Transplantation in Renal Transplantation

HMG CoA reductase inhibitor treatment induces dysglycemia in renal allograft recipients

BACKGROUND

Dysglycemia and dyslipidemia are important metabolic complications of organ transplantation. Statins are widely used to control dyslipidemia; however, long-term use of statins is related to diabetes mellitus (DM) and impaired fasting glucose (IFG). The aim of this study was to evaluate the influence of statins on the development of dysglycemia (IFG and/or DM) in renal allograft recipients.

METHODS

A total of 394 patients without previously known DM or IFG who underwent kidney transplantation were enrolled. Patients were grouped into the two groups according to the use of statin (control, n=149; statin, n=245). The major statins used were fluvastatin (80 mg/d, n=134) and atorvastatin (20 mg/d, n=111). We compared the incidence of IFG or DM during the follow-up period.

RESULTS

The incidence of IFG was higher in the statin group than that in the control group (28.6% vs. 8.7%, P<0.001). The incidence of dysglycemia was significantly higher in the statin group (40.0% vs. 15.4%, P=0.001). Time to development of dysglycemia after transplantation was shorter in the statin group than in the control group (38.8±29.7 vs. 47.2±23.3 months, P=0.002). Statin use was associated with an increased risk for dysglycemia after adjustment for age, sex, body mass index, hypertension, cholesterol levels, hepatitis C infection, and type of immunosuppressant (hazard ratio=3.08, 95% confidence interval=1.91-4.98). The dysglycemic effect was more profound in the patients who used atorvastatin than in those who used fluvastatin (hazard ratio=2.21, 95% confidence interval=1.02-4.76).

CONCLUSION

Statin treatment is associated with an elevation in fasting plasma glucose and in the development of dysglycemia in renal allograft recipients.

Association between 276G/T adiponectin gene polymorphism and new-onset diabetes after kidney transplantation

BACKGROUND

New-onset diabetes after transplantation (NODAT) is a well-recognized complication of kidney transplantation and is associated with poor outcomes. Both adiponectin and chemokine ligand 5 (CCL5) proteins are related to glucose metabolism and genetic variations in their genes can lead to development of NODAT. The aim of this study was to investigate the association of adiponectin and CCL5 genes polymorphisms with NODAT in a population of Caucasian kidney transplant recipients.

METHODS

Two hundred seventy Caucasian kidney transplant recipients (83 with NODAT and 187 without NODAT) were included in a nested case-control study. Patients with pretransplantation diabetes mellitus and multiorgan transplantation were excluded. NODAT diagnosis was determined by American Diabetes Association criteria. Subjects were genotyped for 276G/T adiponectin gene polymorphism (rs1501299) and rs2280789 and rs3817655 CCL5 gene polymorphisms by real-time polymerase chain reaction.

RESULTS

The TT genotype of 276G/T adiponectin gene polymorphism was significantly more frequent in NODAT than non-NODAT patients compared with GG/GT genotypes (recessive model; P=0.031). TT genotype was identified as an independent risk factor for NODAT in Caucasian kidney transplant recipients after adjusting for age at transplantation, pretransplantation body mass index, and use of tacrolimus (TT vs. GG/GT, hazard ratio=1.88, 95% confidence interval=1.03-3.45, P=0.041). There were no differences in genotype distribution and allele frequency of rs2280789 and rs3817655 CCL5 gene polymorphisms between NODAT and non-NODAT groups.

CONCLUSIONS

The 276G/T adiponectin gene polymorphism is associated with NODAT in Caucasian kidney transplant recipients.

Genetics of new-onset diabetes after transplantation

New-onset diabetes after transplantation is a common complication that reduces recipient survival. Research in renal transplant recipients has suggested that pancreatic β-cell dysfunction, as opposed to insulin resistance, may be the key pathologic process. In this study, clinical and genetic factors associated with new-onset diabetes after transplantation were identified in a white population. A joint analysis approach, with an initial genome-wide association study in a subset of cases followed by de novo genotyping in the complete case cohort, was implemented to identify single-nucleotide polymorphisms (SNPs) associated with the development of new-onset diabetes after transplantation. Clinical variables associated with the development of diabetes after renal transplantation included older recipient age, female sex, and percentage weight gain within 12 months of transplantation. The genome-wide association study identified 26 SNPs associated with new-onset diabetes after transplantation; this association was validated for eight SNPs (rs10484821, rs7533125, rs2861484, rs11580170, rs2020902, rs1836882, rs198372, and rs4394754) by de novo genotyping. These associations remained significant after multivariate adjustment for clinical variables. Seven of these SNPs are associated with genes implicated in β-cell apoptosis. These results corroborate recent clinical evidence implicating β-cell dysfunction in the pathophysiology of new-onset diabetes after transplantation and support the pursuit of therapeutic strategies to protect β cells in the post-transplant period.

The incidence of posttransplantation diabetes mellitus during follow-up in kidney transplant recipients and relationship to Fok1 vitamin D receptor polymorphism

BACKGROUND

Posttransplantation diabetes mellitus (PTDM) is a common, serious complication of kidney transplantation. The purpose of this study was to investigate the incidence of and risk factors for PTDM in relationship to Fok1 vitamin D receptor (VDR) polymorphisms.

METHODS

One hundred five kidney transplant recipients with normal glucose values before transplantation were recruited for this study. All patients underwent fasting plasma glucose (FPG) determinations followed by oral glucose tolerance tests (OGTTs) among normal FPG recipients. Every recipient underwent Fok1 VDR polymorphism analysis using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP).

RESULTS

Among 105 recipients, 16 (15.24%) developed new-onset PTDM within 6 months after kidney transplantation. Compared with 89 non-PTDM recipients, the mean age was significantly higher among recipients with PTDM: 47.81 ± 15.54 vs 36.62 ± 11.43 years (P = .001). Patients treated with tacrolimus were more susceptible to PTDM (56.25% vs 28.09%; P = .027). The distribution frequencies of Fok1 genotypes in this cohort followed the Hardy-Weinberg equilibrium. The frequencies of 3 genotypes (FF/Ff/ff; P = .040) and 2 alleles (F/f; P = .009) differed between the 2 groups. Multivariate analysis by logistic regression showed age older than 40 years (odds ratio, 7.774; P = .005), VDR Fok1 f allele (odds ratio, 11.765; P = .012), and tacrolimus therapy (odds ratio, 7.499; P = .007) to be related to the development of PTDM.

CONCLUSIONS

The incidence of newly diagnosed PTDM in this study was 15.24%. Fok1 VDR polymorphism was a genetic marker predicting PTDM risk. Age older than 40 years and tacrolimus were independent risk factors for PTDM.

Can new-onset diabetes after kidney transplant be prevented?

Because the negative consequences of new-onset diabetes mellitus after transplantation (NODAT) diminish the significant gains of kidney transplantation, it is imperative to develop clinical interventions to reduce the incidence of NODAT. In this review, we discuss whether intensive lifestyle interventions that delay or prevent type 2 diabetes mellitus may decrease the incidence of NODAT. We examine the literature pertaining to incidence and timing of onset of NODAT, as well as the risk factors and pathophysiology that NODAT shares with type 2 diabetes mellitus, namely pathways related to increased insulin resistance and decreased insulin secretion. Our central hypothesis is that NODAT results from the same metabolic risk factors that underlie type 2 diabetes mellitus. These risk factors are altered and enhanced by transplantation, "tipping" some transplant recipients with seemingly normal glucose homeostasis before transplant toward the development of NODAT. We describe the diabetogenic properties of transplant immunosuppressive drugs. We describe novel methods of prevention that are being explored, including resting the pancreatic β-cells by administration of basal insulin during the period immediately after transplant. On the basis of the current evidence, we propose that intensive lifestyle modification, adapted for individuals with chronic kidney disease or end-stage renal disease, as well as resting pancreatic β-cells during the immediate postoperative period, may lower the incidence of NODAT.

Preventing and managing hyperglycemia in kidney transplant patients

PURPOSE OF REVIEW

New onset diabetes after kidney transplantation (NODAT) remains a common complication after transplantation and is associated with significant morbidity and mortality. The review will examine recent advances in our knowledge of this metabolic disorder and speculate upon future development.

RECENT FINDINGS

Research continues to broaden the horizon of existing and emerging risk factors that contribute to development of NODAT. Attempts to use this knowledge to develop quantitative risk scoring composites have been made, utilizing either pretransplant or 1-year posttransplantation variables, with variable success. Reassuringly a number of clinical trials have been published, or are currently in progress, that utilize pharmacological intervention for both prevention and management of NODAT. These are both in the form of differential immunosuppressant regimens or use of antiglycemic agents. Upcoming results will prove crucial in developing a genuine evidence-base for NODAT management.

SUMMARY

Rather than simple translation of data from the general to kidney transplant population, clinicians must appreciate that NODAT constitutes a distinct metabolic entity with unique pathophysiology. As such targeted strategies to prevent and manage NODAT require focused investigation to deal with this common complication.

In-vitro characterization of novel and functional regulatory SNPs in the promoter region of IL2 and IL2R alpha in a Gabonese population

Background

The selection pressure imposed by the parasite has a functional consequence on the immune genes, leading to altered immune function in which regulatory T cells (Tregs) induced by parasites during infectious challenges modulate or thwart T effector cell mechanism.

Methods

We identified and investigated regulatory polymorphisms in the immune gene IL2 and its receptor IL2R alpha (also known as CD25) in Gabonese individuals exposed to plentiful parasitic infections.

Results

We identified two reported variants each for IL2 and its receptor IL2R alpha gene loci. Also identified were two novel variants, -83 /-84 CT deletions (ss410961576) for IL2 and -409C/T (ss410961577) for IL2R alpha. We further validated all identified promoter variants for their allelic gene expression using transient transfection assays. Three promoter variants of the IL2 locus revealed no significant expression of the reporter gene. The identified novel variant (ss410961577C/T) of the IL2R alpha revealed a significant higher expression of the reporter gene in comparison to the major allele (P<0.05). In addition, the rs12722616C/T variant of the IL2R alpha locus altered the transcription factor binding site TBP (TATA box binding protein) and C/EBP beta (CCAAT/enhancer binding protein beta) that are believed to regulate the Treg function.

Conclusions

The identification and validation of such regulatory polymorphisms in the immune genes may provide a basis for future studies on parasite susceptibility in a population where T cell functions are compromised.

Gene polymorphisms of interleukin-17 and interleukin-17 receptor are associated with end-stage kidney disease

BACKGROUND

Inflammation could be a causal factor in progression of chronic kidney disease. To date, there is convincing experimental and clinical evidence to support the notion that interleukin (IL)-17-producing T cells contribute to kidney injury in renal diseases. However, the genetic relationship between end-stage renal disease (ESRD) and the T-helper 17 pathway has never been studied. In this study, we hypothesized that polymorphisms of IL-17 or their receptors may be associated with ESRD.

METHODS

A total of 290 nondiabetic ESRD patients and 289 normal controls were included. We analyzed 13 single nucleotide polymorphisms located within the four genes of IL17A, IL17E, IL17RA and IL17RB.

RESULTS

The ESRD patients had a significantly higher allele frequency compared to control subjects for the IL17E rs10137082*C and IL17RA rs4819554*A alleles. Genotyping analysis demonstrated that 2 SNPs among 13 were significantly associated with ESRD after adjusting for age and sex, which were shown by IL17E rs10137082 (odds ratio (OR) 1.48 in codominant 1, OR 1.54 in dominant, OR 1.47 in log-additive) and IL17RA rs4819554 (OR 1.46 in codominant 1, OR 1.79 in codominant 2, OR 1.54 in dominant, OR 1.39 in log-additive).

CONCLUSIONS

Two polymorphisms within the IL17E and IL17RA genes are associated with ESRD independent of age and sex. This is the first finding to suggest that genetic variations of IL17 genes affect the risk of development of ESRD.