Influence of tumor necrosis factor-alpha gene-308 polymorphism on the development of coronary vasculopathy after cardiac transplantation

Predictive Genomics of Adverse Events After Cardiac Surgery

Significant, yet highly individual, thrombotic and inflammatory responses to surgery provide an excellent opportunity for insight into the genomic impact upon a patient's postoperative course. Cardiac surgery elicits the most profound perioperative disturbance and is associated with the highest incidence of adverse outcomes of any elective surgical procedure. Thus, cardiac surgical patients are an ideal population in which to evaluate the influence of complex traits on perioperative morbidity and mortality. This review describes the application of fundamental genetics upon the occurrence of adverse outcomes after cardiac surgery and cardiac transplantation. Specific emphases include a brief primer of the principles of genetics concentrating on the effects of variation within the human genome upon clinical outcomes and the differences between so-called Mendelian traits and complex traits. Four important clinical diseases dealt with in this review as examples of the impact of genetic factors on clinical outcomes are the genetics of heparin-induced thrombocytopenia, heart transplantation rejection and vasculopathy, atrial fibrillation, and infection.

Genetic Influences on Cerebral Outcome After Cardiac Surgery

Just as the influence of genetic variation on patient outcomes is being discussed in many other areas of medicine, so too are its effects on cerebral outcome after cardiac surgery now being described. Whereas early studies focused on neurocognitive outcome, where the single nucleotide polymorphisms of APOE4 and PLA2 were the first investigated genetic targets, stroke is now being elaborated on with related single and multi-gene single nucleotide polymorphisms having been identified. Our work has established key links between post-cardiac surgery stroke and C-reactive protein (3’UTR 1846C/T) and interleukin-6 (-174 G/C) single nucleotide polymorphisms.

Single nucleotide polymorphisms for genes encoding cytokines in the context of cardiac surgery. Part I: Heart transplantation

Cardiovascular diseases remain the leading cause of death in Poland and other countries of the European Union. Patients with end-stage heart failure constitute a patient subgroup for whom the treatment of choice is heart transplantation. Despite advances in immunosuppressive therapy, acute or chronic graft rejection occurs in 20-30% of cases in the first six months after transplantation. The significance of the immune response and inflammation in graft rejection implies the important role of cytokines. Molecular markers are sought to facilitate risk assessment and improve patient care. At present, genetic tests are not used for this purpose, but studies aiming to rectify that have been conducted for years, including studies on single nucleotide polymorphisms of cytokine genes. This paper presents the results of research on the single nucleotide polymorphisms (SNPs) of the IL-2, IL-4, IL-6, IL-10, TGF-β1, PDGF, VEGF, and TNF-α genes in conjunction with heart transplantation. The analyzed data do not allow for reliable application of these genetic tests in clinical practice, but suggest that it is a promising direction which may improve the options of treatment individualization in the future.

Association of cytokine/costimulatory molecule polymorphism and allograft rejection: a comparative review

One reason for genetic variations among human individuals is SNP which may confer diverse disease susceptibility or resistance in a population. Genetic variations in a key immunoregulatory agent can manifest various immunological responses, such as graft rejection. In fact, the outcome of organ transplantation can be impacted by several genetic causes including polymorphisms in genes encoding cytokines and costimulatory molecules in the donor or recipient. Thus, it can be helpful to contemplate the SNPs relating to these immunological determinants in order to achieve an improved transplantation therapy.

Clinical impact of cytokine and growth factor genetic polymorphisms in thoracic organ transplantation

Demographic and clinical risk factors may only partially predict short- and long-term outcomes after thoracic transplantation. The interindividual variability seen in rejection profiles could be related to the recipient's or donor's genetic background. Rejection, either acute or chronic, elicits an alloimmune response that involves a complex network of cytokines, growth factors, adhesion molecules, and other molecules, which may modulate the immune response toward rejection or, conversely, mediate graft acceptance. Herein, the authors discuss the current evidence regarding the importance of genetic polymorphisms as independent predictors of allograft outcome. They believe that pretransplant genotype profiling of patients, in combination with other relevant clinical information, might be useful to predict the risk for posttransplant adverse events and also to facilitate the implementation of individualized immunosuppression.

Effect of cytokine and pharmacogenomic genetic polymorphisms in transplantation

Consolidating the information that we have on pharmacogenetics and on cytokine genetics to produce patient-oriented individualized drug regimens is an important challenge in transplantation medicine. Using a multi-variant approach based on genetic profile and other relevant clinical factors a score system may be developed to predict the severity of rejection, infection, or other complications associated with transplantation. The ultimate goal of these studies is to improve patient outcome through individualized drug regimens.

Genomic Biomarkers and Heart Transplantation

Clinicians have entered into a new paradigm for managing heart transplant patients with use of multimarker gene expression profiling. Early after transplantation, when corticosteroid modification is the main concern, gene expression testing might assist in optimizing the balance of immunosuppression, defraying the occurrence of rejection, and avoiding crisis intervention. Late after transplantation, the reliance on endomyocardial biopsy could be lessened. These advances, if continually validated in practice, could usher in an era of decreased immunosuppression complications, lesser need for invasive surveillance, and more clinical confidence in immunosuppressive strategies.

Microsatellite polymorphism in the heme oxygenase-1 gene promoter and cardiac allograft vasculopathy

BACKGROUND

The heme oxygenase-1 (HO-1) isoenzyme has recently been suggested to protect transplants from ischemia-reperfusion and immunologic injury. Inducibility of this enzyme is modulated by a (GT)n dinucleotide length polymorphism in the HO-1 gene promoter. Short (class S) repeats are associated with greater up-regulation of HO-1 than are long repeats. In the present study, we investigated the impact of the promoter polymorphism on the development of cardiac allograft vasculopathy (CAV) in human heart transplants.

METHODS

We enrolled 152 recipients of a heart allograft with at least 1 year survival post-transplantation in this retrospective study. The HO-1 genotype was assessed using genomic DNA isolated from paraffin-embedded allograft biopsy specimens. Patients were followed angiographically for CAV. Angiographic vessel-wall abnormalities were defined as CAV, and a stenosis of more than 50% in at least 1 vessel area was defined as severe CAV.

RESULTS

Eighty-seven patients (57%) had received a heart from a donor with at least 1 class S allele. Within the mean follow-up period of 9 years, 95 patients (63%) showed signs of CAV, among which 60 patients (40%) developed severe CAV. The frequency of CAV and severe CAV was not significantly different between class S allele recipients and non-recipients (CAV, 57/87 vs 38/65, p = 0.12; severe CAV, 35/87 vs 25/65, p = 0.30).

CONCLUSION

In contrast to recent findings in renal allografts and vascular injury, the HO-1 gene promoter polymorphism does not show an association with the development of CAV in heart transplants.

The promise of protein-based and gene-based clinical markers in heart transplantation: from bench to bedside

Advances in immunosuppression, guided by invasive endomyocardial biopsy for the assessment of graft rejection, have ushered heart transplantation into the clinical arena by the demonstration of acceptable 1-year outcomes. Further decreases in the risk of malignancy and cardiac allograft vasculopathy that improve long-term outcomes, are, however, still desired. Attention has become directed towards the use of markers that can be detected noninvasively to provide insight into underlying molecular and cellular events associated with the immune response and graft function. Various candidate, protein-based markers have been identified: those of alloimmune activation; those of microvascular injury, such as cardiac-specific troponins; those of inflammation, including C-reactive protein; and surrogate markers of cardiac function, including natriuretic peptides such as brain natriuretic peptide. In the realm of genomics, it is becoming increasingly clear that a single molecular marker is unlikely to prove to be useful, but rather that multiple genes from a number of pathways are needed to capture biological complexity and overcome variability in the general population. Thus, the field of protein-based and gene-based biomarkers is advancing rapidly to define its place in clinical therapeutics and to guide immunosuppression according to molecular mechanisms of disease. We discuss here the main findings for the more-successful protein markers identified so far, and the genomic molecular approaches being used to improve heart transplant outcomes.

Impact of cytokine gene polymorphism on cardiovascular risk in renal transplant recipients

Cardiovascular events are the leading causes of morbidity and mortality in renal transplant recipients (RTR). Given the role of inflammation in atherosclerosis, the contribution of functional polymorphisms of cytokines to cardiovascular diseases (CVD) was assessed in RTR in this study. Polymorphisms of tumour necrosis factor alpha (TNF-alpha) gene [-308 (G-->A), -238 (G-->A)], interleukin-10 (IL-10) gene [-1082(A-->G), -819 (T-->C), -592 (A-->C)], transforming growth factor beta 1 (TGF-beta1) gene [codon 10 (T-->C), codon 25 (G-->C)], carotis intima media thickness (CIMT), left ventricular mass index (LVMI), 24-h ambulatory blood pressure and serum lipoprotein homocysteine level, erythrocyte sedimentation rate, serum C-reactive protein (CRP) and serum fibrinogen level of RTR were determined. Seventy-two RTR (26 cadaveric allograft, 46 living-related allograft, 43 male, 29 female) were included in this study. LVMI were similar in TNF-alpha, IL-10 and TGF-beta1 genotypes. Right and left CIMT were higher in TT genotype (n = 16) than CT (n = 46) and CC (n = 10) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (RCIMT, 7.7 +/- 2.2 mm vs. 7.0 +/- 1.4 mm vs. 5.9 +/- 1.4 mm, P = 0.025; LCIMT, 8.5 +/- 2.5 mm vs. 7.0 +/- 1.3 mm vs. 6.1 +/- 1.2 mm, P = 0.002). Lipoprotein (a) level of TT genotype (35.5 +/- 22.5 mg/dl) was higher than CC (4.1 +/- 2.8 mg/dl) and CT (20.4 +/- 11.2 mg/dl) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (P = 0.037). High producers of cytokine IL-10 -1082 [GG (n = 22) vs. AA + AG (n = 50)] and low producers of TGF-beta codon 25 [GC + CC (n = 17) vs. GG (n = 55)] had lower IMT of carotid artery but the difference did not reach statistical significance (P > 0.05). The CIMT of renal transplant patients was similar in IL-10 (-819, -592) and TNF-alpha (-308, -238) genotypes. No difference was observed in 24-h ambulatory blood pressure levels, serum lipoproteins, plasma homocysteine level, erythrocyte sedimentation rate, serum CRP, serum fibrinogen level in IL-10, TNF-alpha and TGF-beta1 genotypes. Besides the well-known factors, TGF-beta1 gene polymorphisms might play a role in CVD in RTR even at early stages of asymptomatic atherosclerosis.

Tumor necrosis factor gene polymorphism and cardiac allograft vasculopathy

BACKGROUND

Cardiac allograft vasculopathy (CAV) limits survival after cardiac transplantation. Tumor necrosis factor-alpha (TNF-alpha) may be a key factor in the development of CAV. Two bi-allelic polymorphisms associated with high TNF-alpha production have been identified in the TNF gene locus, TNFA1/2, at position -308 and TNFB1/2 at +252. We hypothesized that recipient TNFA2 and TNFB2 homozygosity is associated with the development of CAV after heart transplantation.

METHODS

TNF gene polymorphisms were analyzed by multiplex fluorescent solid-phase mini-sequencing in 70 cardiac transplant recipients. Recipients homozygous for TNFA2 or TNFB2 (Group A, n = 29) were compared with recipients heterozygous or homozygous for TNFA1 and TNFB1 (Group B, n = 41). Coronary arteriography was performed annually or when indicated. Cumulative freedom from CAV and survival was calculated according to the Kaplan-Meier test.

RESULTS

Mean follow-up was 3.8 +/- 0.3 years. In Group A, 11 of 29 recipients (38%) developed CAV compared with 9 of 41 (22%) in Group B (p = 0.12). Cumulative freedom from CAV at 3 years was 42% in Group A and 80% in Group B (p = 0.043). In Group A, 11 of 29 recipients (38%) died during follow-up compared with 4 of 41 (10%) in Group B (p = 0.006). Cumulative survival at 3 years was 72% in Group A and 93% in Group B (p = 0.003).

CONCLUSIONS

The results suggest that TNFA2 and TNFB2 allele homozygosity is associated with cardiac allograft vasculopathy and mortality in heart transplant recipients.

Effect of the G-308A polymorphism of the tumor necrosis factor (TNF)-alpha gene promoter site on plasma levels of TNF-alpha and C-reactive protein in smokers: a cross-sectional study

Background

Plasma levels of tumor necrosis factor (TNF)-α and of C-reactive protein (CRP) are elevated in smokers. Previous studies failed to show an association between the G-308A polymorphism in the promoter region of the TNF-α gene and coronary artery disease (CAD). We investigated whether smoking would interact with the TNF-α G-308A polymorphism in determining plasma levels of TNF-α and CRP.

Methods

Study participants with a complete data set in terms of smoking and the TNF-α G-308A polymorphism were 300 middle-aged male and female industrial employees. After excluding 24 irregular smokers, analyses were performed on 198 "non-smokers" (life-long non-smokers or subjects who quit smoking >6 months ago) as compared to 78 "regular smokers" (subjects currently smoking >3 cigarettes/day). All subjects had a fasting morning blood draw to measure plasma levels of TNF-α and CRP by high-sensitive enzyme-linked immunosorbent assays.

Results

The cardiovascular risk factor adjusted analysis regressing log-transformed CRP levels against smoking status, genotype, and smoking-status-genotype interaction revealed a significant main effect for smoking status (F_1,250 = 5.67, p = .018) but not for genotype (F_1,250 = 0.33, p = .57). The interaction-term between genotype and smoking status was not significant (F_1,250 = 0.09, p = .76). The fully adjusted model with plasma TNF-α failed to show significant main effects for smoking and genotype, as well as for the smoking-status-genotype interaction.

Conclusions

The findings suggest that the TNF-α G-308A polymorphism does not mediate the effect of smoking on plasma CRP levels. It remains to be seen whether other genetic polymorphisms along the inflammatory pathway may modulate vascular risk in smokers.

Effect of the TNF-α–promoter polymorphism on cardiac allograft rejection

BACKGROUND

A polymorphism exists in the tumor necrosis factor alpha (TNF-alpha) promoter (position -308, G/A = TNFA1/TNFA2). The TNFA2 allele is associated with increased TNF-alpha production in vitro and has been reported to increase the risk of allograft rejection in pediatric recipients of cardiac transplantation. We examined the effect of the TNFA2 allele on the risk of allograft rejection in adult cardiac transplant recipients.

METHODS

We prospectively analyzed 57 subjects (aged 54 +/- 11 years, 84% men, 49% ischemic) who underwent cardiac transplantation between October 1996 and July 2001. Patients were observed after transplantation (mean, 910 +/- 605 days) and the frequency of allograft rejection (biopsy Grade > or =2) in patients with the TNFA2 allele (Group A, n = 15) was compared with TNFA1 homozygotes (Group B, n = 42). Overall survival and time to rejection episodes also were compared between groups.

RESULTS

The frequency of allograft rejection was similar between groups (Group A, 8/15 [56%]; Group B, 22/42 [52%]; p = 0.77). Time to rejection also was comparable (Group A, 17 +/- 11 days; Group B, 20 +/- 20 days, p = 0.74). Overall post-transplant survival was similar between groups (1- and 2-year percentage survival: Group A, 87% and 78%, Group B, 88% and 82%, p = 0.35).

CONCLUSION

The TNFA2 allele was not associated with increased risk of rejection in adult cardiac transplant recipients. The impact of this polymorphism on overall post-transplant outcomes will require investigation in larger multicenter studies.

Cardiac Allograft Vasculopathy

The purpose of this article is to discuss the pathogenesis, characteristics, and treatment modalities for heart transplant recipients with cardiac allograft vasculopathy (CAV). Cardiac transplantation has become an acceptable mainstream treatment for end-stage cardiac disease. Unfortunately, CAV is the leading cause of death after the first year of transplant. CAV is an accelerated form of obliterative coronary artery disease that occurs in the heart transplant recipient. Currently, retransplantation is the only definitive treatment. Ethical concerns and the shortage of donor organs present a huge obstacle to retransplantation and the long-term outcome of heart transplant recipients.

Coronary artery vasculopathy in pediatric cardiac transplant patients: the therapeutic potential of immunomodulators

The single largest cause of late graft loss in pediatric cardiac transplantation is transplant coronary artery vasculopathy (CAV). The mechanism of CAV remains unknown; it appears to have both immune and non-immune causes. The final common pathway of these mechanisms is endothelial activation, a prothrombotic environment, and endothelial damage with subsequent diffuse intimal proliferation. The disease process has largely been thought to be progressive and unresponsive to treatment. Re-transplantation has been advocated as the only definitive treatment. The appropriate management is largely unknown; intervention or surgical management has had limited utility, while medical management appears to have the most promise. Improvement in outcome can be achieved by optimizing non-immune factors and aggressive management of the immune mechanisms. Long-term survival of transplant patients after diagnosis with CAV is now being reported.