Polymorphism of the transforming growth factor-beta 1 gene correlates with the development of coronary vasculopathy following cardiac transplantation

Non-HLA Genetic Factors and Their Influence on Heart Transplant Outcomes: A Systematic Review

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Background

Improvement of immunosuppressive therapies and surgical techniques has increased the survival rate after heart transplantation. Nevertheless, a large number of patients still experience complications, such as allograft rejection, vasculopathy, kidney dysfunction, and diabetes in response to immunosuppressive therapy. Variants in HLA genes have been extensively studied for their role in clinical outcomes after transplantation, whereas the knowledge about non-HLA genetic variants in this setting is still limited. Non-HLA polymorphisms are involved in the metabolism of major immunosuppressive therapeutics and may play a role in clinical outcomes after cardiac transplantation. This systematic review summarizes the existing knowledge of associations between non-HLA genetic variation and heart transplant outcomes.

Methods

The current evidence available on genetic polymorphisms associated with outcomes after heart transplantation was identified by a systematic search in PubMed and Embase. Studies reporting on polymorphisms significantly associated with clinical outcomes after cardiac transplantation were included.

Results

A total of 56 studies were included, all were candidate gene studies. These studies identified 58 polymorphisms in 36 genes that were associated with outcomes after cardiac transplantation. Variants in TGFB1, CYP3A5, and ABCB1 are consistently replicated across multiple studies for various transplant outcomes.

Conclusions

The research currently available supports the hypothesis that non-HLA polymorphisms are associated with clinical outcomes after heart transplantation. However, many genetic variants were only identified in a single study, questioning their true effect on the clinical outcomes tested. Further research in larger cohorts with well-defined phenotypes is warranted.

Genetic Polymorphism in Cytokines and Costimulatory Molecules in Stem Cell and Solid Organ Transplantation

There is growing evidence supporting the genetic variability outside of HLA system that is contributing to the variation in transplant outcomes. Determining novel predictors could help to identify patients at risk and tailor their immunosuppressive regimens. This article discusses the various single nucleotide polymorphisms in costimulatory molecules and cytokines that have been evaluated for their effect on transplantation. An overview of how gene polymorphism studies are conducted and factors to consider in the experimental design to ensure meaningful data can be concluded are discussed.

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.

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.

Cardiac allograft vasculopathy: diagnosis, therapy, and prognosis

Development of cardiac allograft vasculopathy represents the major determinant of long-term survival in patients after heart transplantation. Due to graft denervation, these patients seldom present with classic symptoms of angina pectoris, and the first clinical presentations are progressive heart failure or sudden cardiac death. Although coronary angiography remains the routine technique for coronary artery disease detection, it is not sensitive enough for screening purposes. This is especially the case in the first year after transplantation when diffuse and concentric vascular changes can be easily detected only by intravascular ultrasound. The treatment of the established vasculopathy is disappointing, so the primary effort should be directed toward early prevention and diagnosis. Due to diffuse vascular changes, revascularization procedures are restricted only to a relatively small proportion of patients with favorable coronary anatomy. Percutaneous coronary intervention is preferred over surgical revascularization since it leads to better acute results and patient survival. Although there is no proven long-term advantage of drug-eluting stents for the treatment of in-stent restenosis, they are preferred over bare-metal stents. Severe vasculopathy has a poor prognosis and the only definitive treatment is retransplantation. This article reviews the present knowledge on the pathogenesis, diagnosis, treatment, and prognosis of cardiac allograft vasculopathy.

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.

Genetic Predisposition and Renal Allograft Failure

Renal allograft rejection or dysfunction often results in graft failure, and remains the major obstacle in the success of renal transplantation. Various immunological and nonimmunological factors are involved in allograft rejection. In addition to human leukocyte antigen loci, several genetically controlled molecules have been identified in recent years as playing important roles in the process of rejection. Genetic variants in genes encoding different T-helper (Th) type 1 and Th2 cytokines, chemokines and their receptors, growth factors, molecules of the renin-angiotensin system, enzymes of the homocysteine pathway, and proteins acting as substrates of immunosuppressive drugs impact on the success of engraftment and highlight the concept of genetic predisposition to allograft rejection. This review evaluates specific genetic variants and their functional roles in graft failure, with an emphasis on the latest methodologies available for genotyping, and appropriate strategies to enable them to become a tool of predictive and individualized medicine to ensure better transplant outcome.

Transforming growth factor-beta polymorphisms and cardiac allograft rejection

BACKGROUND

Cytokine gene polymorphisms regulate cytokine expression. We analyzed transforming growth factor-beta (TGF-beta) allelic variation in codon 25 in susceptibility to acute rejection episodes in cardiac transplant recipients.

METHODS

Between June 1997 and December 2001, 123 de novo heart transplants were performed at UAB with analysis based on 109 patients. Clinical and laboratory data were recorded at intervals up to 1 year post-transplant. Recipient genotypes for TGF-beta (codon 25) were determined using polymerase chain reaction (PCR) sequence-specific primers. Correlations between TGF-beta genotypes and acute rejection were made using Kaplan-Meier plots and parametric hazard models.

RESULTS

Of the patients enrolled, 72% had at least one rejection and 46% had multiple rejections in the first year post-transplant. Among those > or =55 years of age at transplant, patients with the GG genotype had significantly fewer rejections as compared to those with the CC or GC genotype (1.25 vs 2.5, p < 0.01). There was no difference in risk of rejection between the genotype groups among patients <50 years of age at transplant (p = 0.43). Similar results were observed when we used time to cumulative Grade 2R or greater rejection as the outcome.

CONCLUSION

The GG TGF-beta genotype may protect against acute rejection in older recipients during the first year after transplant.

Development of transplant vasculopathy in aortic allografts correlates with neointimal smooth muscle cell proliferative capacity and fibrocyte frequency

OBJECTIVE

Transplant vasculopathy consists of neointima formation in graft vasculature resulting from vascular smooth muscle cell recruitment and proliferation. Variation in the severity of vasculopathy has been demonstrated. Genetic predisposition is suggested as a putative cause of this variation, although cellular mechanisms are still unknown. Using a rat aorta transplant model we tested the hypothesis that kinetics of development of transplant vasculopathy are related to neointimal smooth muscle cell proliferative capacity and fibrocyte frequency, the latter being putative neointimal smooth muscle ancestral cells.

METHODS

Aortic allografts were transplanted in Lewis and Brown Norway, as well as MHC-congenic Lewis.1N and Brown Norway.1L recipients. Severity of transplant vasculopathy was quantified 4, 8, 12 and 24 weeks after transplantation. Host-endothelial chimerism, as a reflection of vascular injury, was determined by specific immunofluorescence. Neointimal smooth muscle cell proliferative capacity was determined in vitro and in situ. Fibrocyte frequency and phenotype were determined after in vitro culture by cell counting, immunofluorescence and in situ zymography.

RESULTS

Compared to Lewis, Brown Norway recipients developed accelerated transplant vasculopathy which is dependent on the presence of Brown Norway non-MHC-encoded determinants. Accelerated transplant vasculopathy was associated with increased levels of host-endothelial chimerism and increased neointimal smooth muscle cell proliferation, the latter being accompanied by increased endothelial and smooth muscle cell-derived neuropilin-like protein mRNA expression. Moreover, accelerated transplant vasculopathy was associated with increased frequency of circulating gelatinase-expressing CD45(+)vimentin(+) fibrocytes.

CONCLUSION

Susceptibility for transplant vasculopathy appears to be genetically controlled and correlates with neointimal smooth muscle cell proliferative capacity and circulating fibrocyte frequency.

The G/G genotype of transforming growth factor beta 1 (TGF-beta1) single nucleotide (+915G/C) polymorphism coincident with other host and environmental factors is associated with irreversible bronchoconstriction in asthmatics

Irreversible airflow obstruction may develop in some cases of asthma even in absence of known risk factors such as smoking and environmental insults and despite implementing apparently appropriate therapy. This implies that genetic factors may significantly contribute to determining the severity in the course of the disease. The published reports on genetic predisposition to irreversible bronchoconstriction in asthma, however, are relatively scarce, and disregard its potential association with transforming growth factor (TGF)-beta1 gene polymorphism despite established role that TGF-beta1 plays in airway remodelling. We tested TGF-beta1 single-nucleotide polymorphisms (SNPs) at position +869 of codon 10 (leucine or proline) and position +915 of codon 25 (arginine or proline) for association with irreversible bronchoconstriction in a case-control study involving 110 patients with asthma and 109 controls. Multivariate logistic regression analysis revealed that genotype G/G at codon 25 was significantly associated with irreversible bronchoconstriction in asthmatics (odds ratio = 4.44; 95% confidence interval: 1.00-19.61; P = 0.05), but only after adjustment for gender, disease duration and smoking index. The influence of SNPs at codon 10 on irreversible airway obstruction was not significant. Our results suggest that presence of SNP (+915G/G) at codon 25 in TGF-beta1 gene may predispose to the development of irreversible bronchoconstriction in asthmatic patients, but only when coincident with the male gender, habitual smoking and relevant duration of the disease.

Cytokine Genotype Polymorphisms in Breast Carcinoma: Associations of TGF-β1 with Relapse

Markers of angiogenesis, cell proliferation, and cytokine regulation are associated with the development and course of autoimmune and malignant diseases. We investigated associations between cytokine production genotypes in breast cancer patients compared with controls and explored associations with known prognostic indices and relapse status. Eighty-eight females with breast carcinoma (BC) were studied in this case-control study comparing the cytokine genotypes of TNF-alpha TGF-beta1, IL-10, IL-6, and IFN-gamma with controls. Cytokine polymorphisms were identified by sequence-specific primers for codons, introns, or promoters regulating cytokine production. Patient characteristics, such as estrogen and progesterone receptor status, DNA ploidy, Her-2 neu expression, lymph node involvement, tumor size, and relapse status were evaluated. Cytokine genotypes were not associated with breast cancer compared with controls. Correlations between TGF-beta1 high-production genotypes and greater than four positive lymph nodes (OR=2.3; p=ns) and TNF-alpha high-production genotype and the mean level of estrogen receptor expression (66 +/- 24 vs. 34 +/- 36, p=0.016) were identified. The median patient follow-up interval from diagnosis to evaluation was 50.1 months (range 13-387 months). Relapse status was known for 84 of the patients. The odds of relapse in TGF-beta1 codon 10 CC genotypes was 2.81 times that in TGF-beta1 high-production genotypes (OR=2.81; 95% CI for OR: 1.0, 7.8; p=0.04). Mean progesterone receptor expression was decreased in relapsed patients (40.9 +/- 29.9% vs. 23.1 +/- 24.5, p=0.05). The other cytokine genotypes studied (IL-10, IL-6, IFN-gamma, and TNF-alpha production were not associated with breast cancer overall or relapse status. In this study, TGF-beta1 low-production genotypes (TGF-beta1 10 CC) were associated with an increased odds of disease relapse. This finding should be confirmed in a longitudinal study to further investigate the regulatory function of cytokine production as a prognostic indicator of relapse.

Heterotopic vascularized murine cardiac transplantation to study graft arteriopathy

The development of microsurgical techniques has facilitated the establishment of fully vascularized cardiac transplantation models in small mammals. A particularly useful model that has evolved for the study of cardiac allograft vasculopathy (CAV) is a heterotopic (abdominal) vascularized murine cardiac transplantation model. Using this model has permitted the elucidation of genetic, immune and non-immune factors contributing to the development of this inexorable pathological condition, which compromises half of all human cardiac transplants. This protocol details methods for performing the transplant, histomorphometric assessment of the graft vasculature and functional evaluation of the transplanted heart. In experienced hands, the surgical procedure requires approximately 75 min to complete, and vasculopathy results are obtained at 2 months. This model entails a fully vascularized implantation technique in which the donor ascending aorta and pulmonary artery are sutured end-to-side to the recipient abdominal aorta and inferior vena cava, respectively. As this model reliably reproduces immunological and non-immunological features of CAV, investigators can thoroughly explore contributory mechanisms, diagnostic modalities and therapeutic approaches to its mitigation.

The anti-inflammatory properties of cocoa flavanols

Signs of chronic or acute inflammation have been demonstrated in most cardiovascular diseases of multifactorial pathogenesis, including atherosclerosis and chronic heart failure. The triggers and mechanisms leading to inflammation may vary between clinical conditions but they share many common mediators, including specific patterns of eicosanoid and cytokine production. Certain cocoa-based products can be rich in a subclass of flavonoids known as flavanols, some of which have been found in model systems to possess potential anti-inflammatory activity relevant to cardiovascular health. Indeed, experimental evidence demonstrates that some cocoa-derived flavanols can reduce the production and effect of pro-inflammatory mediators either directly or by acting on signaling pathways. However, it should be noted that the evidence for any beneficial effects of cocoa flavanols in providing a meaningful anti-inflammatory action has been gathered predominantly from in vitro experiments. Therefore, additional research in well-designed human clinical experiments, using cocoa properly characterized in terms of flavanol content, would be a welcome addition to the evidence base to determine unambiguously if this benefit does indeed exist. If so, then flavanol-rich cocoa could be a potential candidate for the treatment, or possibly prevention, of the broad array of chronic diseases that are linked to dysfunctional inflammatory responses.

Prevention of Chronic Renal Allograft Rejection by SERP-1 Protein

BACKGROUND

In previous studies we have demonstrated that Serp-1, a myxoma virus encoded serine protease inhibitor, dramatically inhibits neointimal hyperplasia in vascular injury and aortic transplant models. Here we examined the effect of peritransplant Serp-1 administration on chronic renal allograft rejection.

METHODS

Rat renal transplants were performed with sequential recipient sacrifice on postoperative days 2, 10 and 140 to examine both the acute and chronic effects of Serp-1 in recipient rats.

RESULTS

Serp-1 administration reduced early posttransplant injury (POD 2) with less acute tubular and vascular necrosis. This translated into a reduction of the characteristic late stage changes of chronic rejection (POD 140), with significantly decreased glomerulosclerosis and neointimal hyperplasia. Effects of Serp-1 treatment were already evident as early as POD 2 with markedly decreased levels of TGF-beta mRNA witnessed at both the early and late time points (POD 2, 10 and 140).

CONCLUSION

We have demonstrated that peritransplant Serp-1 viral protein decreased early injury and allowed reduced chronic rejection in a rat renal model. Recipients treated with Serp-1 are associated with a decrease in TGF-beta mRNA levels in the allografts suggesting that the serine protease inhibitor may inhibit TGF-beta transcription and its profibrotic effects.

Impact of TGFβ1 Gene Polymorphisms on Acute and Chronic Rejection in Pediatric Heart Transplant Allografts

BACKGROUND

The aim of this study was to assess the influence of IL-10 and TGFbeta1 gene polymorphisms on the development of acute rejection and coronary disease in pediatric heart transplant recipients.

METHODS

Patients were classified as either Rejectors or Nonrejectors. Coronary artery disease (CAD) was diagnosed by angiography or on macroscopic examination. Genotyping PCR-SSP were performed for IL-10 and TGFbeta1 (codon 10 and 25) in 111 patients. Thirty-nine were Rejectors and 31 developed CAD.

RESULTS

The proportion of IL-10 low-producers was higher in Rejectors than in Nonrejectors (respectively 46% versus 22%, P=0.009). IL-10 gene polymorphism was not associated with CAD. TGFbeta1-codon10-25 high-producers were 92.3% in Rejectors and 75% in Nonrejectors (P=0.026), 93.5% in patients with CAD and 76.2% in patients free from CAD (P=0.037). TGFbeta1-codon25 high-production separately analyzed correlated with CAD (31/31 high-producers in CAD=100% versus 69/80 in noCAD patients=86.2%, P=0.03). TGFbeta1-codon10 gene polymorphisms were not associated with CAD.

CONCLUSION

IL-10 low-producers have an increased risk of acute rejection. High-expressors of TGFbeta1-codon10-25 have an increased risk of acute rejection and CAD, while TGFbeta1-codon25 high-production is associated with coronary disease. Genetic polymorphism may reveal patients at high-risk in whom therapies and monitoring should be adjusted.

Immune Response Gene Polymorphisms in Renal Transplant Recipients

BACKGROUND

T-cell activation and regulation are under genetic control and vary between individuals. However, the influence of functional immune response gene polymorphisms on transplant outcomes remains controversial.

METHODS

A case-control design compared 100 white renal transplant recipients with or without acute graft rejection during the first year posttransplant and 50 normal controls. The polymorphic frequencies of the T-cell signaling genes CD45, CD40L and CTLA-4, and the cytokine genes TNF-alpha, IFN-gamma, IL-10 and TGF-beta1 were studied. The primary analysis examined rejection risk, and subsidiary analyses graft failure and patient death.

RESULTS

Multivariate analysis showed no significant association between acute rejection and single nucleotide polymorphisms in CTLA-4, TGF-beta1, IL-10 or TNF-alpha genes or dinucleotide repeat polymorphisms in IFN-gamma and CD40L genes. Allele CD40L-147 was associated with reduced graft failure (P=0.004), and TGFb-25pro with increased graft failure (P=0.0007), although the latter showed a bidirectional dose effect. There was no significant association between patient death and any polymorphisms in the genes examined. The variant (G) allele of the CD45 gene was not detected in the study population. Minor differences in carriage rates observed by univariate analysis did not predict graft or patient outcome in multivariate analysis.

CONCLUSION

The primary analysis demonstrated no significant association between the immune response gene polymorphisms examined and acute renal graft rejection in Caucasian patients receiving triple immunosuppression. Subsidiary analyses suggesting an influence of CD40L and TGFbeta1 genes on graft survival require independent confirmation.

Transforming growth factor-beta1 SNPs: genetic and phenotypic correlations in progressive kidney insufficiency

Associations have been described between polymorphisms of cytokine and growth factor genes and susceptibility to, or progression of, an increasing number of diseases. TGF-beta1 plays an important role in the pathogenesis of experimental and clinical glomerulosclerosis and tubulointerstitial fibrosis. In this study, single nucleotide polymorphisms (SNPs) in the TGFbeta1 gene were investigated as possible markers for the progression of chronic kidney failure (CKF). 145 Caucasian patients with CKF were screened for four TGFbeta1 SNPs: T-509C in the promoter region; Arg25Pro and Leu10Pro in exon 1 and Thr263Ile in exon 5. There were significant differences between CKF patients and controls in allele frequencies of two of the SNPs, Leu10Pro (p = 0.038) and C-509T (p = 0.02) and in haplotype distributions (p = 0.0175), indicating an association with susceptibility to CKF. We also observed a significant association between progression of CKF and homozygosity for Arg25 (odds ratio 3.77, 95% confidence interval 1.57-9.04, p = 0.002). Homozygosity for Arg25 was also associated with severity of proteinuria at diagnosis (p = 0.038), plasma TGF-beta1 protein levels (p = 0.01), and severity of glomerulosclerosis (p = 0.04). Homozygosity for -509T was associated with severity of proteinuria at diagnosis (p = 0.0017), level of renal tubular TGF-beta1 immunostaining (p = 0.0006) and with severity of renal interstitial inflammatory cellular infiltration (p = 0.01). Tubular TGF-beta1 immunostaining was significantly higher in biopsies with inflammatory cellular infiltration compared those without inflammation (p = 0.0048). There was a significant difference in haplotype distributions between CKF patients with progressive, as opposed to non-progressive disease (p = 0.0484). TGFbeta1 SNPs may be useful prognostic indicators for the progression of CKF.

Interleukin-6 Polymorphism: A Genetic Risk Factor for Cardiac Transplant Related Coronary Vasculopathy?

AIMS

Interleukin- (IL-) 6 is a pleiotropic cytokine with effects on the acute phase response, inflammation, and vascular function. A G to C polymorphism has been described at position -174 in the promoter region of the IL-6 gene. We investigated the influence of this polymorphism on the development of cardiac transplant related coronary vasculopathy (CV).

METHODS

Sequence specific polymerase chain reaction identified the -174*G/C allele for 116 cardiac transplant recipients. Coronary disease was identified by routine surveillance post-transplant coronary angiography.

RESULTS

Prevalence of the -174*G/C polymorphism was different between the transplant and control cohorts; *CC 27.6%, *CG 45.7%, and *GG 26.7% vs. 13.2%, 44.1% and 42.7% respectively (p = 0.004). Median time to the first diagnosis of CV was different between the 3 alleles; *CC 2.8 years (2.0-4.0); *CG 3.9 years (2.1-4.5); *GG 5.3 years (3.2-6.1) (p = 0.05). By Kaplan-Meier survival analysis C homozygotes developed CV significantly earlier than the other cohorts (p = 0.035). At 5 years 100% of C homozygotes had evidence for CV. G homozygotes had a more gradual onset of CV with an approximate 60% prevalence at 5 years. *CC genotype was the most predictive risk factor for CV development (Hazard ratio 4.2 (95% CI 1.3-12.9); p = 0.014). Increasing donor age was also significant (Hazard ratio 1.04 (95% CI, 1.0-1.08); p = 0.023).

CONCLUSIONS

Polymorphism at position -174 within the promoter region of the IL-6 gene may be an important risk factor for cardiac transplant related coronary vasculopathy. This may improve patient selection and allow tailored immunosuppressive treatment.

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.

Gender-related association between the TGFB1+869 polymorphism and multiple sclerosis

Our objective was to investigate whether polymorphisms and haplotypes in the TGFB1 gene are associated with susceptibility or disease characteristics of multiple sclerosis (MS). In 247 MS patients and 194 controls, single nucleotide polymorphisms (SNPs) at position +869 (Leu10Pro) and position +915 (Arg25Pro) in the signaling sequence of the TGFB1 gene were determined, and the distribution of alleles, genotypes, and haplotypes was related to clinical data. In addition, magnetic resonance imaging (MRI) data were studied in a subgroup of patients (n = 96). The allele distribution of the two polymorphisms studied was in Hardy-Weinberg equilibrium in patients and in controls. No association was found with any of the three haplotypes found in the Dutch population, denoted as haplotype 1 (TGFB1+869T-TGFB1+915G), haplotype 2 (TGFB1+869C-TGFB1+915G), and haplotype 3 (TGFB1+869C-TGFB1+915C). However, the TGFB1+869 genotype CC was significantly more frequent in patients (p = 0.031, chi2 test). The highest frequency of the TGFB1+869 genotype CC was observed in male patients (25.2% vs. 10.0% in controls, p = 0.004, chi2 test), and carriership of TGFB1+869 allele C was correspondingly increased in male patients (74.8% vs. 56.7%, p = 0.008, chi2 test, OR 2.27, 95% CI 1.23-4.17). Although there was no association with clinical markers of disease progression, patients homozygous for TGFB1+869 allele C showed a significantly higher annual increase in two MRI parameters: ventricular fraction (central atrophy) and T1-hypointense lesion load (matrix destruction). The TGFB1 T+869C (Leu10Pro) gene polymorphism is associated with MS susceptibility, especially in males, and with a more destructive course of the disease as illustrated by MRI.

The effect of recipient cytokine gene polymorphism on cardiac transplantation outcome

We determined the association between clinical outcomes after heart transplantation and gene polymorphism in five cytokines (tumor necrosis factor-alpha, transforming growth factor (TGF)-beta, interleukin-10, interleukin-6, and interferon-gamma) reported to influence expression in vitro. Ninety-five patients were studied. Cytokine genotyping was performed by sequence specific priming polymerase chain reaction. Clinical outcomes studied in the first posttransplant year included: (1) documented viral, bacterial, or fungal infection; (2) cytomegalovirus infection; (3) acute cellular rejection (International Society for Heart and Lung Transplantation > or = grade IIIA); (4) time to first rejection episode; and (5) the development of allograft vasculopathy. Patients with the TGF-beta genotype 10 T/T 25 G/G or 10 T/C 25 G/G had a longer time to first rejection (median time to first rejection episode 321 days) than those with the TGF-beta genotype 10C/C 25 G/C or 10 C/C 25 C/C (median time to first rejection 88 days). There was a trend toward a higher frequency of the tumor necrosis factor-alpha genotype -308 G/A or A/A in patients without infection (19/59, 32%) as compared with patients with infection (5/31, 16%). In both cases, these differences failed to reach significance when adjusted for multiple comparisons. No other significant association was found with clinical outcomes and polymorphisms in the five cytokine genes studied in this population.

A novel polymorphism of the gene encoding furin, a TGF-β1 activator, and the influence on cardiac allograft vasculopathy formation

BACKGROUND

Coronary vasculopathy (CV) is an important determinant of survival following cardiac transplantation. We have previously shown that G915C polymorphism of the Transforming Growth Factor-beta1 (TGF-beta1) gene strongly influences CV development. Furin is a proprotein convertase enzyme important in TGF-beta1 activation. We investigated for polymorphism within the promoter region of the gene for furin (fur). Allelic variation of the fur gene, in conjunction with TGF-beta1 polymorphism, was subsequently related to the development of CV.

METHODS AND RESULTS

The fur gene promoter region (position -1199 to +39) was analysed by SSCP and sequencing. A C/T single nucleotide substitution polymorphism at position -231* was identified. Using PCR the fur and TGFB1 genotypes were identified in 115 cardiac transplant recipients. CV was diagnosed at routine surveillance post-transplant coronary angiography. Fur polymorphism had no influence on vasculopathy development; median time to diagnosis, *C/C homozygotes, 2.27 years (2.10-4.32), *C/T heterozygotes 2.97 years (2.09-4.24), *T/T homozygotes 2.65 years (2.33-4.08), (P=0.95). Allelic variation did not influence Kaplan Meier actuarial analysis of disease onset (P=0.54). Ninety-three percent of recipients were high TGF-beta1 producers. We used fur polymorphism to substratify patients with the +915*G/G TGFB1 (high producing) allele. Fur polymorphism did not influence CV development within this TGF-beta1 high producer cohort, when analysed by time to first diagnosis and Kaplan Meier testing.

CONCLUSIONS

We have described a novel polymorphism at position -231* in the gene encoding furin. The fur -231* single nucleotide polymorphism in isolation, or in conjunction with TGFB1 polymorphism, is not useful as a genetic risk marker for cardiac transplant associated coronary vasculopathy.

Donor and recipient-transforming growth factor-beta 1 polymorphism and cardiac transplant-related coronary artery disease

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) has been implicated in the pathogenesis of coronary vasculopathy following cardiac transplantation. The TGFB1 gene contains polymorphisms at positions +915* (Arg25Pro) and +869* (Leu10Pro) which may influence TGF-beta1 expression. We investigated the relationship between the development of coronary vasculopathy and the prevalence of these alleles in a cardiac transplant population.

METHODS

Vasculopathy was diagnosed at routine surveillance post-transplant coronary angiography. Using sequence-specific polymerase chain reaction we identified the TGFB1 +915* and +869* genotypes in 147 cardiac transplant recipients and 134 cardiac donors.

RESULTS

TGFB1 +915*C allele carriers (low producers) made up 10.5% of the recipient population but were significantly less likely to develop coronary vasculopathy (P=0.03). Median time to diagnosis was 6.0 years (3.9-8.72) in +915*C allele carriers compared to 2.75 years (2.10-4.22) in *G/G homozygotes (p=0.002). Pre- and 1 year post-transplant clinical variables were equivalent between the two groups. Multivariate analysis identified the recipient +915*G/G genotype (hazard ratio 2.96 (95% CI, 1.09-9.98); p=0.039), donor age (hazard ratio 1.05 (95% CI, 1.02-1.09); p=0.008) and number of acute rejection episodes of ISHLT grade 3 or greater in the first year (hazard ratio 1.12 (95% CI, 1.01-1.23); p=0.03) as significant predictors of vasculopathy. The recipient TGFB1 +869*, and both alleles in the donor, had no influence on vasculopathy development.

CONCLUSIONS

Recipient TGFB1 +915* genotype influences the development of cardiac transplant-related coronary vasculopathy. This gives an important insight to the pathophysiology of the disease. On the contrary, donor TGFB1 +915* and TGFB1 +869* polymorphisms do not appear to be important and cannot be used as genetic risk factors.

The microextraction of RNA from archival cardiac allografts embedded in paraffin

One of the difficulties encountered in studying rejection in patients is the availability of tissue. The goal of our study was to isolate RNA from archival allograft tissue, and to demonstrate that it is of suitable quality for further molecular experimentation. Thirty-two paraffin embedded cardiac and five renal allograft archival samples were obtained after IRB approval, from a total of 18 transplant patients (13 cardiac/five renal transplant patients) from a search of the University of Tennessee's teaching hospitals. RNA was extracted from the paraffin blocks and amplified by reverse transcription-polymerase chain reaction (RT-PCR). Grade 3A and higher and non-rejection samples were tested. In addition, normal mouse liver tissue was isolated for comparison. Negative control samples were also included. RT-PCR amplification of 18s RNA, 324 bp target sequences, revealed readily detectable bands. Only one block that was 3 years old did not yield detectable RNA secondary to presumed degradation. The negative control showed no bands at 324 bp. We conclude that RNA from archived allograft tissue can be used for further experiments. The use of this tissue offers some distinct advantages when studying correlation of gene expression with clinical outcome and therapeutic response.

Transforming growth factor beta1 genotype and change in left ventricular mass during antihypertensive treatment--results from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation versus Atenolol (SILVHIA)

BACKGROUND

Angiotensin II, via the angiotensin II type 1 (AT1) receptor, may mediate myocardial fibrosis and myocyte hypertrophy seen in hypertensive left ventricular (LV) hypertrophy through production of transforming growth factor beta1 (TGF-beta1); AT1-receptor antagonists reverse these changes. The TGF-beta1 G + 915C polymorphism is associated with interindividual variation in TGF-beta1 production. No study has yet determined the impact of this polymorphism on the response to antihypertensive treatment.

HYPOTHESIS

We aimed to determine whether the TGF-beta1 G + 915C polymorphism was related to change in LV mass during antihypertensive treatment with either an AT1-receptor antagonists or a beta1-adrenoceptor blocker. The polymorphism was hypothesized to have an impact mainly on the irbesartan group.

METHODS

We determined the association between the TGF-beta1 genotype and regression of LV mass in 90 patients with essential hypertension and echocardiographically diagnosed LV hypertrophy, randomized in a double-blind study to receive treatment for 48 weeks with either the AT1-receptor antagonist irbesartan or the beta1-adrenoceptor blocker atenolol.

RESULTS

Irbesartan-treated patients who were carriers of the C-allele, which is associated with low expression of TGF-beta1, responded with a markedly greater decrease in LV mass index (LVMI) than subjects with the G/G genotype (adjusted mean change in LVMI -44.7 g/m2 vs. -22.2 g/m2, p = 0.007), independent of blood pressure reduction. No association between genotype and change in LVMI was observed in the atenolol group.

CONCLUSIONS

The TGF-beta1 G + 915C polymorphism is related to the change in LVMI in response to antihypertensive treatment with the AT1-receptor antagonist irbesartan.

Prediction of normal tissue radiosensitivity from polymorphisms in candidate genes

BACKGROUND AND PURPOSE

Single nucleotide polymorphisms (SNPs) in genes related to the biological response to radiation injury may affect clinical normal tissue radiosensitivity. This study investigates whether seven selected SNPs in five candidate genes influence risk of subcutaneous fibrosis and telangiectasia after radiotherapy.

PATIENTS AND METHODS

The 41 patients included in this study were given post-mastectomy radiotherapy in 1978-1982 and subsequently evaluated in detail with regard to several different normal tissue reactions. SNPs in TGFB1 (codons 10, 25 and position -509), SOD2 (codon 16), XRCC3 (codon 241), XRCC1 (codon 399) and APEX (codon 148) were analyzed by PCR and single nucleotide primer extension. Dose-response curves were established for subcutaneous fibrosis and telangiectasia in patients with different genotypes. Differences in radiosensitivity were quantified in terms of ED(50) values and enhancement ratios.

RESULTS

For TGFB1, the Pro/Pro genotype in codon 10 and the T/T genotype in position -509 correlated positively with risk of subcutaneous fibrosis. The SOD 2 codon 16 Val/Ala genotype was associated with increased risk of subcutaneous fibrosis when compared to the Val/Val genotype. The Thr/Thr genotype in XRCC3 codon 241 correlated with increased risk of subcutaneous fibrosis as well as telangiectasia. The Arg/Arg genotype in XRCC1 codon 399 was associated with increased risk of radiation-induced subcutaneous fibrosis. For these polymorphisms, enhancement ratios between 1.09 and 1.25 were found. Combined analysis of multiple SNPs demonstrated that the risk of subcutaneous fibrosis correlated with the number of risk alleles in such a manner that patients with few risk alleles exhibited a remarkable degree of radioresistance.

CONCLUSION

The present study established significant correlations between five SNPs and risk of radiation-induced normal tissue reactions. These findings support the assumption that clinical normal tissue radiosensitivity should be regarded as a phenomenon dependent on the combined effect of variation in several genes and indicate that models based on multiple genetic markers may have the potential to predict normal tissue responses after radiotherapy.

The transforming growth factor-beta1 gene polymorphism (G915C) is not associated with systemic lupus erythematosus

Lymphocyte production of transforming growth factor (TGF)-beta1 is decreased in systemic lupus erythematosus (SLE). The lack of this immunoregulatory cytokine may contribute to the characteristic T cell disregulation and aberrant B cell stimulation in SLE patients. The less common C allele of the TGFB1 polymorphism (G915C) is associated with a lower TGF-beta1 production capacity. We performed a population-based case-control study to analyse the impact of this polymorphism on disease susceptibility, on clinical SLE manifestations and autoantibody production. A total of 203 German Caucasian SLE patients (fulfilling the 1982 ACR disease duration 11.5 +/- 7.0 years) and 158 ethnically, age- and sex-matched healthy controls were genotyped with a mutagenically separated polymerase chain reaction. There were no significant differences in the genotype distribution and allele frequencies between patients (915 C = 0.08) and healthy controls (915 C = 0.10). Comparing subgroups of patients, we found no association of major disease manifestations or specific autoantibodies with TGFB1 genotypes or alleles. The TGFB1 polymorphism (G915C) neither significantly contributes to the disease susceptibility, nor predisposes to clinical and immunological manifestations typical of SLE. Further studies are needed to corroborate the pathogenic role of TGF-beta1 in SLE patients and to identify the precise genetic elements controlling its production.

Prospective analysis of single nucleotide polymorphisms of the transforming growth factor beta-1 gene in Peyronie's disease

PURPOSE

The detection of increased expression of transforming growth factor beta-1 (TGF-beta1) in Peyronie's disease plaques and the possibility of initiating a Peyronie's disease-like condition by intratunical injection of a synthetic heptopeptide with TGF-beta-like activity in an animal model has provided evidence for the central role of this cytokine in the pathogenesis of this entity. Recently 2 defined single nucleotide polymorphisms in the coding region of the TGF-beta1 gene have been described that are associated with different levels of TGF-beta1 production. Based on these data we prospectively investigated the genetic association of distinct TGF-beta1 genotypes with Peyronie's disease.

MATERIALS AND METHODS

DNA samples from 111 consecutive patients with idiopathic Peyronie's disease and 100 controls were genotyped for the 2 defined dimorphic single nucleotide polymorphisms T869C and G915C in the coding region of the TGF-beta1 gene using allele specific polymerase chain reaction.

RESULTS

We found an increased frequency of the homozygous genotype of the single nucleotide polymorphism G915C in patients with Peyronie's disease compared with healthy controls (89.2% versus 79%, p = 0.04). However, there were no significant differences in allele frequencies of the single nucleotide polymorphism T869C.

CONCLUSIONS

Experimental data from other investigators have shown that TGF-beta1 has an important role in the etiopathology of Peyronie's disease. Our results indicate that the homozygous wild type of the G915C single nucleotide polymorphism in the coding region of the TGF-beta1 gene, which was recently associated with elevated TGF-beta1 production and pulmonary fibrosis, may influence the predisposition to Peyronie's disease. However, it does not represent a major genetic risk factor.

Combined analysis of cytokine genotype polymorphism and the level of expression with allograft function in African-American renal transplant patients

Cytokine gene polymorphism and expression levels were evaluated in a group of African-American patients who had undergone renal transplantation. It was hypothesized that possession of specific cytokine alleles might be influential in predisposing the recipient to allograft rejection. Thus, we sought to establish a relationship between cytokine gene polymorphism, the levels of cytokine expression, and the outcome of allograft function. Cytokine genotypes and mRNA transcript levels of IL-2, TNF-alpha, TGF-beta1, IL-10, IL-6 and IFN-gamma were determined using peripheral blood cells. Genomic DNA samples from 77 transplant recipients and 77 controls were tested by a multiplex PCR with specific primers for the above cytokines. The frequency distributions of cytokines were analyzed in respect to the clinical characterization, including delayed graft function (DGF), rejection episodes (REs) and stable graft function (SGF). The mRNA transcript level was tested both at pre- and early post-transplantation (day 1 and day 4) with primers for coding regions of the above cytokines in a RT-PCR assay. The majority of recipients with successful graft function were matched with their donors for only three out of the six HLA alleles. We have shown that the TGF-beta1 T/C G/G high producer and IFN-gamma T/A intermediate producer genotypes were associated with allograft rejection, whereas low IFN-gamma producer and high IL-10 producer genotypes were significantly protective of the allograft. There was some correlation between the TGF-beta1 high producer genotype and DGF, but it was not statistically significant. Overall, 77% of those who experienced REs carried the TGF-beta1 T/C G/G, high producer genotype as compared with 52% who experienced DGF, 39% with SGF (P<0.01, RR=2.0), and 27.3% of controls (P<0.003, RR=2.6). The IFN-gamma T/A intermediate producer genotype was found in 69.2% of patients with REs as compared with 26.8% of patients with SGF (P<0.008, RR=2.85). The IL-10, ATA/ATA low producer genotype was found in 38.5% of recipients with REs and 14.6% of recipients without REs (P<0.04, RR=0.53). Expression levels of mRNA transcript were correlated with genotype data, except for the TGF-beta1 high producer genotype where there was no significant difference between the level of mRNA transcript at pre- and post-transplantation. Low DRbeta1 and high DPbeta1 expression by recipient peripheral blood mononuclear cells before transplantation was associated with more SGF, whereas high DRbeta1 and low DPbeta1 expression at pretransplantation was associated with more REs (DRbeta1, P<0.001 and DPbeta1, P<0.05, respectively). We concluded that, dual analysis of cytokine genotype and expression levels by peripheral cells may be an important clue to understanding the contribution of the recipient's immune response to an allograft pre- and post-transplantation. Identification of peripheral markers diagnostic of rejection could allow advance anticipation of clinical outcome, and might reduce the need for tissue biopsy.

Recipient gene polymorphisms in the Th-1 cytokines IL-2 and IFN-gamma in relation to acute rejection and graft vascular disease after clinical heart transplantation

IL-2 and IFN-gamma are associated with acute rejection (AR) and graft vascular disease (GVD) after clinical heart transplantation. Polymorphisms in the genes of IL-2 (T-330G in the promoter) and IFN-gamma (CA repeat in the first intron) influence the production levels of these cytokines. Therefore, these polymorphisms might have an effect on the outcome after transplantation. To investigate possible effects of genetic variations in IL-2 and IFN-gamma genes on AR and GVD, we analyzed the IL-2 T-330G and the IFN-gamma CA repeat polymorphism in DNA of 301 heart transplant recipients. No associations were found for allele or genotype distributions between patients with or without AR (IL-2 allele frequency: P=0.44, genotype distribution: P=0.46; IFN-gamma allele frequency P=0.10, genotype distribution 12 repeats allele: P=0.21). Also, no associations were found analyzing the number (0 vs. 1 vs. >or=1) of AR (IL-2 allele frequency: P=0.59; genotype distribution: P=0.37; IFN-gamma allele frequency: P=0.27, genotype distribution 12 repeats allele: P=0.41) or analyzing the polymorphisms in patients with AR within the first month or thereafter (IL-2 allele frequency: P=0.45, genotype distribution: P=0.38; IFN-gamma allele frequency: P=0.21, genotype distribution 12 repeats allele: P=0.41). Analyzing both polymorphisms in relation to GVD, resulted in comparable allele and genotype distributions (IL-2 allele frequency: P=0.75; genotype distribution: P=0.77; IFN-gamma allele frequency: P=0.70, genotype distribution 12 repeats allele: P=0.63). In conclusion, we did not detect an association between the IL-2 T-330G promoter polymorphism and CA repeat polymorphism in the first intron of the IFN-gamma gene and AR or GVD after heart transplantation.

Cocoa flavonols and procyanidins promote transforming growth factor-beta1 homeostasis in peripheral blood mononuclear cells

Evidence suggests that certain flavan-3-ols and procyanidins (FP) can have a positive influence on cardiovascular health. It has been previously reported that FP isolated from cocoa can potentially modulate the level and production of several signaling molecules associated with immune function and inflammation, including several cytokines and eicosanoids. In the present study, we examined whether FP fractions monomers through decamers modulate secretion of the cytokine transforming growth factor (TGF)-beta(1) from resting human peripheral blood mononuclear cells (PBMC). A total of 13 healthy subjects were studied and grouped according to their baseline production of TGF-beta(1). When cells from individuals with low baseline levels of TGF-beta(1) (n = 7) were stimulated by individual FP fractions (25 microg/ml), TGF-beta(1) release was enhanced in the range of 15%-66% over baseline (P < 0.05; monomer, dimer, and tetramer). The low-molecular-weight FP fractions (<or=pentamer) were more effective at augmenting TGF-beta(1) secretion than their larger counterparts (>or=hexamer), with the monomer and dimer inducing the greatest increases (66% and 68%, respectively). In contrast to the above, TGF-beta(1) secretion from high TGF-beta(1) baseline subjects (n = 6) was inhibited by individual FP fractions (P < 0.05; trimer through decamer). The inhibition was most pronounced with trimeric through decameric fractions (28%-42%), and monomers and dimers moderately inhibited TGF-beta(1) release (17% and 23%, respectively). Given the vascular actions associated with TGF-beta(1), we suggest that in healthy individuals, homeostatic modulation of its production by FP offers an additional mechanism by which FP-rich foods can potentially benefit cardiovascular health.

The polymorphism of transforming growth factor-beta1 gene in Japanese patients with systemic sclerosis

BACKGROUND

Transforming growth factor (TGF)-beta has been shown to be a potent stimulator of collagen production by fibroblasts, and could play a role in the pathogenesis of systemic sclerosis (SSc).

OBJECTIVE

To study the possible involvement of TGF-beta1 gene polymorphism in Japanese patients with SSc.

METHODS

Fifty-nine patients with SSc and 110 normal subjects were studied. Genomic DNA was extracted from skin tissues, and was amplified in a thermal cycler, generating a TGF-beta1 gene fragment with a size of 294 bp. The T to C transition at T869C (Leu10Pro) and the G to C transition at G915C (Arg25Pro) were identified by digestion with MspA1I and BglI, respectively.

RESULTS

At T869C (Leu10Pro), the frequency of the C allele in SSc (65.3%) was significantly higher than in normal controls (50.5%) (P < 0.01). SSc showed C/C allele 42.4%, C/T 45.8% and T/T 11.2%. Normal controls showed C/C allele 26.4%, C/T 48.2% and T/T 25.5%. The frequency of the C/C allele in SSc was significantly higher than in normal controls, in comparison with the T/T allele (P < 0.02), but no significant difference was found between the frequency of the C/C allele vs. the C/T allele. The frequency of the C/C allele showed no significant difference between diffuse and limited SSc. At G915C (Arg25Pro), all the normal controls and SSc patients showed only the G/G allele. These results are different from a previous study in which the frequency of the T/T allele was high in SSc at T869C (Leu10Pro).

CONCLUSIONS

This discrepancy may indicate that Japanese patients with SSc show a different genetic predisposition to TGF-beta1.

Does variability in normal tissue reactions after radiotherapy have a genetic basis – where and how to look for it?

Cancer patients exhibit large patient-to-patient variability in normal tissue reactions after radiotherapy. Several observations support the hypothesis that clinical normal tissue radiosensitivity is influenced by genetic factors. However, very little is known about the genetic variation possibly underlying inter-individual differences in normal tissue reactions when unselected cancer patients undergo radiotherapy. It seems reasonable to assume that clinical radiosensitivity of normal tissues should be regarded as a so-called complex trait depending on the combined effect of several different genetic alterations. Single nucleotide polymorphisms (SNPs) make up 90% of naturally occurring sequence variation in the human genome and SNPs in genes related to the biological response to ionising radiation may affect clinical radiosensitivity. Rare genetic variants could also possibly play an important role. Thus, the 'allelic architecture' underlying differences in normal tissue reactions may be rather complicated. Recent advances in high throughput genotyping and bio-informatics provide unprecedented opportunities to unravel the genetic basis of clinical normal tissue radiosensitivity. However, to achieve maximum benefit from these advances, carefully designed clinical studies with an accrual of hundreds or thousands of patients are probably needed.

Polymorphisms in immunoregulatory genes: towards individualized immunosuppressive therapy?

In organ transplantation, successful immunosuppression requires that both rejection and infection episodes be minimized. Unfortunately it is currently impossible to predict individual dose requirement for immunosuppressive drugs, but a number of studies of various immune response genes are now being performed with a view to identifying genotypes associated with rejection and/or infection. The key role of cytokines in the immune response and other processes, including fibrosis, has concentrated most of this attention on polymorphisms in cytokine genes. Data on polymorphisms in genes encoding tumor necrosis factor-alpha, transforming growth factor-beta, interferon-gamma and interleukin (IL)-1, 4, 6 and 10 together with the IL-4 receptor have been analyzed but so far there is currently no indication of any consistently positive associations between graft rejection and any of these polymorphisms. Studies of other immunomodulatory genes including the CTLA4 gene and the chemokine receptor CCR-5 have proved more positive though the data, so far, are only preliminary. In conclusion, additional large series studies of these and other cytokine genes, as well as other immunoregulatory gene polymorphisms of proven functional significance are needed to achieve major progress in this area.

Cytokine gene polymorphisms and acute human liver graft rejection

Interindividual differences exist in the capacity to produce cytokines. It has been reported that levels of in vitro cytokine production measured after stimulated cell culture are associated with polymorphisms in cytokine genes. Moreover, a correlation between heart, kidney, liver, and lung graft rejection or survival with cytokine gene polymorphisms has been described. In the present study, we analyzed the association of gene polymorphisms in T helper subtype 1 (T(H)1-), T(H)2-, and regulatory-type cytokines with human liver allograft rejection. Patients who received a primary liver graft from 1992 onward and were seen at the transplant outpatient clinic since then were included on this study (n = 89). Patients were HLA typed routinely. Biopsy-proven acute rejection occurred in 41 of 89 patients. After informed consent, blood was collected and DNA was obtained. Using amplification-refractory mutation system polymerase chain reaction, the following cytokine gene polymorphisms were determined: IL-2+166, IL-2-330, IL-15+13689, IL-15-80, TNF-A-308, TNFd3, IFN-G+874 (T(H)1-type cytokines), IL-4+33, IL-4-590, IL-6-174, IL-10-592, IL-10-819, IL-10-1082, IL-13+2043, IL-13-1055 (T(H)2 type cytokines), TGF-B1+869, and TGF-B1+915 (regulatory-type cytokines). Univariate analysis showed that polymorphisms of IL-10-1082, TGF-B1+869, and HLA-DR6 were significantly related to liver graft rejection. Multiple logistic regression analysis was used to assess which variables remained significantly predictive of acute rejection. Multivariate analysis showed that TGF-B1+869 and HLA-DR6 were independently associated with the occurrence of acute rejection. These findings suggest a role for the regulatory-type cytokine transforming growth factor-beta1 in human liver graft rejection.

No association between transforming growth factor beta gene polymorphism and acute allograft rejection after cardiac transplantation

Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine, which inhibits both development of Th1 and Th2 subsets and the Th1 proinflammatory response. TGF-beta1 production is influenced through several single nucleotide polymorphisms (SNP) in the structural gene and promoter region. Acute rejection of transplants depends on the Th1/Th2 balance within the graft, high levels of TGF-beta1 shift this balance towards Th2. We investigated whether genotypes of 4 SNP (-800 and -509 in the promoter region, codon 10 and codon 25 in the first exon) were correlated with cardiac disease or with incidence of rejection after heart transplantation (HTX). Genotypes were determined for 70 HTX patients and 61 donors by sequencing or oligonucleotide ligation assay. No association between SNP genotypes and heart disease or acute transplant rejection was observed. We conclude that genetic variation in the TGF-beta1 gene neither influences the existence of cardiomyopathy nor the incidence of rejection upon HTX.

High transforming growth factor-beta and extracellular matrix mRNA response in renal allografts during early acute rejection is associated with absence of chronic rejection

BACKGROUND

A case-control study was performed to investigate whether mRNA levels of transforming growth factor-beta (TGF-beta) and various extracellular matrix molecules in renal transplant biopsy specimens, taken during acute rejection episodes within 6 months of transplantation, discriminate between patients who show deterioration of graft function and develop chronic rejection (CR+ group), and those who do not develop chronic rejection (CR- group).

METHODS

Patients in both the CR+ group (n=10) and the CR- group (n=18) had at least one biopsy-proven acute rejection episode within the first 6 months after transplantation. The two groups were similar with respect to donor-, recipient-, and transplantation-related clinical variables. Histologic changes (Banff classification) and the timing of the acute rejection episodes in the biopsies studied did not differ between groups. Renal cortical mRNA levels of TGF-beta1, collagen alpha1(IV), collagen alpha1(I), decorin, and the household gene glyceraldehyde-3-phosphate dehydrogenase in biopsy specimens taken during acute rejection episodes were quantified by real-time polymerase chain reaction.

RESULTS

The mean TGF-beta mRNA level in the CR- group was 3.4 times higher than that in the CR+ group (P<0.04). The mean collagen IV, collagen I, and decorin mRNA levels in the CR- group were 4.2 times (P<0.05), 5.1 times (not significant), and 3.2 times (P<0.05) higher, respectively, than those in the CR+ group. The mean TGF-beta to decorin mRNA ratios between the two patient groups did not differ significantly.

CONCLUSIONS

In summary, high mRNA levels for TGF-beta, collagen IV, and decorin, but not histopathologic changes, in biopsies taken during acute rejection episodes early after kidney transplantation are associated with absence of chronic rejection. We hypothesize that TGF-beta might have beneficial effects during acute rejection through its known antiinflammatory actions or as an inducer of tissue repair.

The influence of genomics on outcome after cardiovascular surgery

Recent findings in molecular research suggest that the outcome of cardiovascular surgery is at least partly determined by the individual patient's genetic predisposition to react to surgical trauma and extracorporal circulation. The activation of cellular as well as humoral cascades occurs in the perioperative period, and influences the extent of pro- and anticoagulation and pro- and anti-inflammation. These events contribute to the incidence and severity of perioperative ischaemia or organ dysfunction, and thus determine adverse outcomes in patients undergoing cardiac surgery. Candidate genes that are possibly involved in the development of adverse outcomes not only consist of genes relevant to the field of coagulation and inflammation, but also genes functioning in lipid metabolism, ion channels, membrane integrity and others. Genomic variations may prove to serve as future diagnostic tools for the risk stratification of patients undergoing cardiovascular surgery.

Association of polymorphisms of the transforming growth factor-beta1 gene with the rate of progression of HCV-induced liver fibrosis

BACKGROUND

The objective of the present study was to elucidate possible relationships between four polymorphisms of the TGF-beta1 gene (-800G>A; -509C>T; Leu10Pro; Arg25Pro) and stage, histological activity grade and progression rate of liver fibrosis, classified according to the METAVIR-score.

METHODS

Three study groups, i.e. 48 patients with hepatic fibrosis (26 with known duration of hepatitis C virus infection), 47 patients with non-fibrotic diseases and 50 healthy blood donors, were analyzed for TGF-beta1 polymorphisms using ARMS-PCR and sequence analysis. The concentrations of total TGF-beta1 in plasma and of hyaluronan, P-III-NP and activities of transminases in serum were measured.

RESULTS

The presence of proline at codons 10 and/or 25 was associated with a faster progression of fibrosis than other polymorphisms. Patients with the genotype (25)ArgPro developed fibrosis significantly faster (0.23 units/year) than those having (25)ArgArg (0.08 units/year). Similarly, the fibrosis progression rate of patients with genotypes (10)LeuPro and (10)ProPro was almost three times as fast as of those having genotype (10)LeuLeu. Stage and histological activity grade of fibrosis in (25)ArgPro in comparison to (25)ArgArg were higher. Also (10)LeuPro showed a higher average stage of fibrosis than (10)LeuLeu. The TGF-beta1 plasma concentrations of patients with hepatic fibrosis were not significantly different between carriers of (25)ArgArg and (25)ArgPro genotypes. The frequency of the genotype (25)ArgPro in liver fibrotic patients was about three times that of the control group whereas the frequency distribution of the genotype (25)ArgArg tended to lower frequency in the fibrosis group. TGF-beta1-promoter polymorphisms did not show any correlation with stage, grade or progression of liver fibrosis.

CONCLUSION

Our results indicate that the heterozygous ArgPro of codon 25 predicts significantly faster fibrotic progression of chronic hepatitis C than the homozygous (25)ArgArg genotype. The homozygous LeuLeu genotype of codon 10 showed a slow progression of fibrosis.