Tumor necrosis factor-alpha gene polymorphism and death due to acute cellular rejection in a subgroup of heart transplant recipients

Noninvasive biomarkers for prediction and diagnosis of heart transplantation rejection

For most patients with end-stage heart failure, heart transplantation is the treatment of choice. Allograft rejection is one of the major post-transplantation complications affecting graft outcome and survival. Recent advancements in science and technology offer an opportunity to integrate genomic and other omics-based biomarkers into clinical practice, facilitating noninvasive evaluation of allograft for diagnostic and prognostic purposes. Omics, including gene expression profiling (GEP) of blood immune cell components and donor-derived cell-free DNA (dd-cfDNA) are of special interest to researchers. Several studies have investigated levels of dd-cfDNA and miroRNAs in blood as potential markers for early detection of allograft rejection. One of the achievements in the field of transcriptomics is AlloMap, GEP of peripheral blood mononuclear cells (PBMC), which can identify 11 differentially expressed genes and help with detection of moderate and severe acute cellular rejection in stable heart transplant recipients. In recent years, the utilization of GEP of PBMC for identifying differentially expressed genes to diagnose acute antibody-mediated rejection and cardiac allograft vasculopathy has yielded promising results. Advancements in the field of metabolomics and proteomics as well as their potential implications have been further discussed in this paper.

Gut microbiota, endotoxemia, inflammation, and oxidative stress in patients with heart failure, left ventricular assist device, and transplant

BACKGROUND

Gut microbial imbalance may contribute to endotoxemia, inflammation, and oxidative stress in heart failure (HF). Changes occurring in the intestinal microbiota and inflammatory/oxidative milieu during HF progression and following left ventricular assist device (LVAD) or heart transplantation (HT) are unknown. We aimed to investigate variation in gut microbiota and circulating biomarkers of endotoxemia, inflammation, and oxidative stress in patients with HF (New York Heart Association, Class I-IV), LVAD, and HT.

METHODS

We enrolled 452 patients. Biomarkers of endotoxemia (lipopolysaccharide and soluble [sCD14]), inflammation (C-reactive protein, interleukin-6, tumor necrosis factor-α, and endothelin-1 adiponectin), and oxidative stress (isoprostane) were measured in 644 blood samples. A total of 304 stool samples were analyzed using 16S rRNA sequencing.

RESULTS

Gut microbial community measures of alpha diversity were progressively lower across worsening HF class and were similarly reduced in patients with LVAD and HT (p < 0.05). Inflammation and oxidative stress were elevated in patients with Class IV HF vs all other groups (all p < 0.05). Lipopolysaccharide was elevated in patients with Class IV HF (vs Class I-III) as well as in patients with LVAD and HT (p < 0.05). sCD14 was elevated in patients with Class IV HF and LVAD (vs Class I-III, p < 0.05) but not in patients with HT.

CONCLUSIONS

Reduced gut microbial diversity and increased endotoxemia, inflammation, and oxidative stress are present in patients with Class IV HF. Inflammation and oxidative stress are lower among patients with LVAD and HT relative to patients with Class IV HF, whereas reduced gut diversity and endotoxemia persist in LVAD and HT.

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.

Multicenter Analysis of Immune Biomarkers and Heart Transplant Outcomes: Results of the Clinical Trials in Organ Transplantation-05 Study

Identification of biomarkers that assess posttransplant risk is needed to improve long-term outcomes following heart transplantation. The Clinical Trials in Organ Transplantation (CTOT)-05 protocol was an observational, multicenter, cohort study of 200 heart transplant recipients followed for the first posttransplant year. The primary endpoint was a composite of death, graft loss/retransplantation, biopsy-proven acute rejection (BPAR), and cardiac allograft vasculopathy (CAV) as defined by intravascular ultrasound (IVUS). We serially measured anti-HLA- and auto-antibodies, angiogenic proteins, peripheral blood allo-reactivity, and peripheral blood gene expression patterns. We correlated assay results and clinical characteristics with the composite endpoint and its components. The composite endpoint was associated with older donor allografts (p < 0.03) and with recipient anti-HLA antibody (p < 0.04). Recipient CMV-negativity (regardless of donor status) was associated with BPAR (p < 0.001), and increases in plasma vascular endothelial growth factor-C (OR 20; 95%CI:1.9-218) combined with decreases in endothelin-1 (OR 0.14; 95%CI:0.02-0.97) associated with CAV. The remaining biomarkers showed no relationships with the study endpoints. While suboptimal endpoint definitions and lower than anticipated event rates were identified as potential study limitations, the results of this multicenter study do not yet support routine use of the selected assays as noninvasive approaches to detect BPAR and/or CAV following heart transplantation.

Anti-skeletal muscle atrophy effect of Oenothera odorata root extract via reactive oxygen species-dependent signaling pathways in cellular and mouse model

Skeletal muscle atrophy can be defined as a decrease of muscle volume caused by injury or lack of use. This condition is associated with reactive oxygen species (ROS), resulting in various muscular disorders. We acquired 2D and 3D images using micro-computed tomography in gastrocnemius and soleus muscles of sciatic-denervated mice. We confirmed that sciatic denervation-small animal model reduced muscle volume. However, the intraperitoneal injection of Oenothera odorata root extract (EVP) delayed muscle atrophy compared to a control group. We also investigated the mechanism of muscle atrophy's relationship with ROS. EVP suppressed expression of SOD1, and increased expression of HSP70, in both H2O2-treated C2C12 myoblasts and sciatic-denervated mice. Moreover, EVP regulated apoptotic signals, including caspase-3, Bax, Bcl-2, and ceramide. These results indicate that EVP has a positive effect on reducing the effect of ROS on muscle atrophy.

Meta-analysis of cytokine gene polymorphisms and outcome of heart transplantation

We performed a systematic review and meta-analysis with the aim of assessing the association between cytokine gene polymorphisms and graft rejection in heart transplantation. We identified relevant studies from Medline and Embase using PubMed and Ovid search engines, respectively. Allele frequencies and allele and genotypic effects were pooled. Heterogeneity and publication bias were explored. Four to 5 studies were included in pooling of 3 gene polymorphisms. The prevalences of the minor alleles for TNF α -308, TGF β 1-c10, and TGF β 1-c25 were 0.166 (95% CI: 0.129, 0.203), 0.413 (95% CI: 0.363, 0.462), and 0.082 (95% CI: 0.054, 0.111) in the control groups, respectively. Carrying the A allele for the TNF α -308 had 18% (95% CI of OR: 0.46, 3.01) increased risk, but this was not significant for developing graft rejection than the G allele. Conversely, carrying the minor alleles for both TGF β 1-c10 and c25 had nonsignificantly lower odds of graft rejection than major alleles, with the pooled ORs of 0.87 (95% CI: 0.65, 1.18) and 0.70 (95% CI: 0.40, 1.23), respectively. There was no evidence of publication bias for all poolings. An updated meta-analysis is required when more studies are published to increase the power of detection for the association between these polymorphisms and allograft rejection.

Interleukin-10-1082G/A polymorphism and acute liver graft rejection: A meta-analysis

AIM: To investigate the association between interleukin (IL)-10-1082 (G/A) promoter polymorphism and acute rejection (AR) in liver transplant (LT) recipients.

METHODS: Two investigators independently searched the Medline, Embase, China National Knowledge Infrastructure, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95% CIs for IL-10-1082 G/A polymorphism and AR were calculated in a fixed- and a random-effects model as appropriate.

RESULTS: This meta-analysis included seven case-control studies, which comprised 652 cases of LT recipients in which 241 cases developed AR and 411 cases did not develop AR. Overall, the variant A allele was not associated with AR risk when compared with the wild-type G allele (OR = 0.94, 95% CI: 0.64-1.39). Moreover, similar results were observed when the AA genotype was compared with the AG/GG genotype (OR = 1.05, 95% CI: 0.55-2.02). When stratifying for ethnicity, no significant association was observed among either Caucasians or Asians. Because only one study was performed in Asian patients, the result of subgroup analysis by ethnicity would not be reliable for Asians. Limiting the analysis to the studies with controls in the Hardy-Weinberg equilibrium, the results were persistent and robust. No publication bias was found in the present study.

CONCLUSION: This meta-analysis suggests that IL-10-1082 G/A polymorphism may be not associated with AR risk in LT recipients among Caucasians.

TNF receptors differentially signal and are differentially expressed and regulated in the human heart

Tumor necrosis factor (TNF) utilizes two receptors, TNFR1 and 2, to initiate target cell responses. We assessed expression of TNF, TNFRs and downstream kinases in cardiac allografts, and compared TNF responses in heart organ cultures from wild-type ((WT)C57BL/6), TNFR1-knockout ((KO)), TNFR2(KO), TNFR1/2(KO) mice. In nonrejecting human heart TNFR1 was strongly expressed coincidentally with inactive apoptosis signal-regulating kinase-1 (ASK1) in cardiomyocytes (CM) and vascular endothelial cells (VEC). TNFR2 was expressed only in VEC. Low levels of TNF localized to microvessels. Rejecting cardiac allografts showed increased TNF in microvessels, diminished TNFR1, activation of ASK1, upregulated TNFR2 co-expressed with activated endothelial/epithelial tyrosine kinase (Etk), increased apoptosis and cell cycle entry in CM. Neither TNFR was expressed significantly by cardiac fibroblasts. In (WT)C57BL/6 myocardium, TNF activated both ASK1 and Etk, and increased both apoptosis and cell cycle entry. TNF-treated TNFR1(KO) myocardium showed little ASK1 activation and apoptosis but increased Etk activation and cell cycle entry, while TNFR2(KO) myocardium showed little Etk activation and cell cycle entry but increased ASK1 activation and apoptosis. These observations demonstrate independent regulation and differential functions of TNFRs in myocardium, consistent with TNFR1-mediated cell death and TNFR2-mediated repair.

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.

Influence of cytokine and intercellular adhesion molecule-1 gene polymorphisms on acute rejection in pediatric renal transplantation

Immune response regulation by cytokines is a key to understanding AGR. The influence of the functional polymorphisms in genes coding for TNF-alpha (-308G > A), IL-10 (-819C > T, and -1082A > G), IFN-gamma [(CA)n], TGF-beta1 (+869T > C), and iCAM-1 (R241G and E469K), in addition to HLA and gender matching on the presentation of AGR in 51 pediatric renal recipients during a 36-month post-transplantation follow-up were analyzed. Also, donors and a control group were genotyped. All groups were within Hardy-Weinberg equilibrium for all polymorphisms except IL-10-819C > T and TNF-alpha (p < 0.005 and p < 0.01, respectively) in recipients. Transplants with gender mismatch showed a higher risk for AGR than those between individuals with gender match (OR, 4.227; p = 0.010). Recipients with a high-production compared with low-production TNF-alpha allele experienced earlier AGR (p = 0.030), and those with high-production alleles of both TNF-alpha and IFN-gamma showed a further increased risk (OR = 11.129, p = 0.024). These findings support the notion that a single genotype cannot by itself explain an event as complex as AGR. The sum or combination of different specific alleles of these genes could better account for the immune response to an allograft.

Polymorphisms in cytokine genes and their association with acute rejection and recurrence of hepatitis B in Chinese liver transplant recipients

BACKGROUND

Acute rejection (AR) and hepatitis B virus (HBV) recurrence after liver transplantation (LT) are the two major complications leading to chronic graft dysfunction. Genomic polymorphisms in interleukin (IL)-10, tumor necrosis factor (TNF)alpha and transforming growth factor (TGF)beta1 genes have been found to affect the susceptibility to certain diseases. However, the relationship between cytokine gene polymorphisms and risk of AR as well as HBV recurrence after LT in Han Chinese has not been reported. The objective of the present study was to investigate the association of polymorphisms within these cytokine genes with the risk of AR as well as HBV recurrence.

METHODS

One hundred eighty six Chinese LT recipients in which 41 patients developed AR and 29 patients experienced HBV recurrence were enrolled; 151 age- and gender-matched healthy individuals were selected as controls. Single-nucleotide polymorphisms (SNPs) at loci of IL-10 -1082, -819, -592, and TNFalpha -308, -238, as well as TGFbeta1 -988, -800, -509, +869, and +915 were determined by using DNA sequencing and then confirmed by restriction fragment length polymorphism (PCR-RFLP). Analyses of linkage disequilibrium and haplotype frequency were performed using Haploview program.

RESULTS

The -819 and -592 polymorphisms in the IL-10 gene were in complete linkage (r(2) = 1). Another linkage was found at -509 and +869 in the TGFbeta1 gene (r(2) = 0.66). A significant difference was observed in the distribution of allelic frequencies at position -819 and -592 in the IL-10 gene between ARs and non-ARs (p = 0.036, OR = 1.134, 95% CI 0.999-1.287 and p = 0.036, OR = 1.134, 95% CI 0.999-1.287, respectively). After adjustment for a Bonferroni correction, there was no significant difference between the polymorphism and AR (p >0.05). Furthermore, the overall genotype distribution between HBV recurrence patients and non-HBV recurrence patients was also not significantly different (p >0.05).

CONCLUSIONS

Our study suggests that gene polymorphisms of IL10, TNFalpha, and TGFbeta1 do not have a major independent role in AR and HBV recurrence after LT and may not be risk factors of AR and HBV recurrence after LT in Chinese liver transplant recipients.

TNFα-induced cytoprotection requires the production of free radicals within mitochondria in C2C12 myotubes

We previously reported that tumour necrosis factor alpha (TNFalpha) can mimic classic ischemic preconditioning (IPC) in both cells and heart. However, the signalling pathways involved remain incompletely understood. One potential protective pathway could be TNFalpha-induced reactive oxygen species (ROS). We hypothesized that TNFalpha cytoprotection occurs through the generation of ROS which originate within the mitochondria. C(2)C(12) myotubes were preconditioned with either a short period of hypoxia (IPC) or a low concentration of TNFalpha (0.5 ng/ml) prior to a simulated ischemic insult. ROS generation was evaluated on cells stained with dichlorofluorescin diacetate (DCFH-DA) by flow cytometry. The source of TNFalpha-induced ROS was examined with Mitotracker Red CM-H(2)XRos. The bioenergetics of the mitochondria were evaluated by investigation of the respiratory parameters and the inner mitochondrial membrane potential. Pretreatment with TNFalpha improved cell viability compared with the simulated ischemic control (TNFalpha: 75 +/- 1% versus 34 +/- 1% for the control: p<0.001). The ROS scavenger, N-2-mercaptopropionyl-glycine (MPG), reduced the viability of TNFalpha-stimulated cells to 15 +/- 1% (p<0.001 versus TNFalpha). Similar results were obtained with IPC. TNFalpha stimulation increased ROS production mainly in the mitochondria, and this increase was abolished in the presence of MPG. Addition of TNFalpha to the cells increased State 2 respiration and modestly depolarised the membrane potential prior to the ischemic insult. In conclusion, TNFalpha-induced ROS generation can occur within the mitochondria, resulting in temporal mitochondrial perturbations which may initiate the cytoprotective effect of TNFalpha.

Genetic polymorphisms in patients with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a family of clonal disorders characterized by dyshematopoiesis and susceptibility to acute myelogenous leukemia. Tumor necrosis factor-a (TNF-alpha) and transforming growth factor-beta (TGF-beta) are cytokines that play key roles in the pathogenesis of MDS. There have been several reports on the presence of genetic polymorphisms in the DNA sequence encoding the leader sequence of the TGF-beta protein, and in the -308 promoter region of TNF-alpha. The association between TNF-alpha and TGF-beta1 gene polymorphism and the susceptibility to MDS and the progression of the disease was investigated. As compared with healthy control subjects (n = 74), patients with MDS (n = 55) showed no significant deviations in genotype or allele frequencies of TNF-alpha. Similarly, there were no differences in the distribution of TNF-alpha genotypes between the MDS patients with only anemia (mild group) and those with bi- or pancytopenia (severe group). On the other hand the TT homozygosity at codon 10 in exon 1 of TGF-beta1 gene was associated with a severe degree of cytopenia [95% CI OR = 4.889, p = 0.0071]. These findings suggest that the investigated genetic polymorphisms do not predispose to the development of MDS, but that TGF-beta1 gene polymorphism may affect the disease progression.

Pharmacogenetics in Transplant Patients

Pharmacogenetics holds the potential to allow individualized dosing of immunosuppressive agents to optimize their therapeutic effect while minimizing adverse effects. As more pharmacogenetic information accumulates, the prospect of reducing or discontinuing the intensive therapeutic drug monitoring of immunosuppressants looks attractive. However, the long process of developing useful clinical information from basic information on the genes of interest is at a very early stage, and our present information does not supercede pharmacokinetic or blood concentration monitoring of immunosuppressants. The most extensive blood concentration/dose information available is on tacrolimus and its dosing related to CYP3A5 and ABCB1 gene polymorphisms. Although CYP3A5 genotype is definitely associated with tacrolimus dosing, the only recommendation presently published is for an arbitrary doubling of the starting tacrolimus dose in CYP3A5 expressors. For cyclosporine, sirolimus, and corticosteroids, the presently available pharmacogenetic information does not permit pharmacokinetic predictions. The pharmacodynamics of immunosuppressants, as evidenced by effects on acute rejection or adverse drug effects, have considerably more potential for prediction by pharmacogenetic models. Drug-resistant rejection, nephrotoxicity, steroid resistance and osteonecrosis, and even patient survival may ultimately be predicted by models incorporating multiple gene polymorphisms and other critical patient information. At this point, treatment algorithms can be developed that will allow us to individualize a transplant patient's immunosuppressive therapy.

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.

The ‐308 Promoter Polymorphism in the Tumour Necrosis Factor Gene in Patients with Lichen Planus

The close chromosomal proximity of major histocompatibility complex and tumour necrosis factor genes may suggest the involvement of the latter in the pathogenesis of immunological diseases associated with HLA antigenes. The major histocompatibility complex antigens may play a certain role in the pathogenesis of lichen planus. Therefore we examined the -308 promoter polymorphism of tumour necrosis factor gene in patients with lichen planus. Sixty-six patients and 66 age- and sex-matched controls participated in the study. Genomic DNA from patients and controls was typed for tumour necrosis factor (-308) polymorphism using an allele-specific polymerase chain reaction. We did not find any correlation between genotype distribution, allele frequency and lichen planus. In our study we failed to observe any association between a genotype and mean level of tumour necrosis factor in plasma of our patients.

Cytokine gene polymorphism and early graft rejection in liver transplant recipients

Cytokines, which play important roles in allograft rejection, show variable production among individuals. These variations may be related to genetic polymorphisms within the regulatory regions of the cytokine genes. We investigated the association between the role tumor necrosis factor alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interferon gamma (IFN-gamma), interleukin (IL)-10 and IL-6 gene polymorphisms and early graft rejection among liver transplant recipients. Forty-three liver transplant recipients enrolled in this study were divided into 2 groups based on events in the first 2 months posttransplantations, namely, those experiencing at least 1 rejection episode (n = 26) or those without any episode (n = 17). The allele or genotype frequencies of cytokine gene polymorphisms showed no difference between liver recipients with or without nonrejection. In conclusion, there was no significant correlation between early graft rejection and cytokine gene polymorphism of TNF-alpha, TGF-beta, IL-10, IL-6, and IFN-gamma in liver transplant recipients.

Clinical Importance of Transforming Growth Factor-β but Not of Tumor Necrosis Factor-α Gene Polymorphisms in Patients with the Myelodysplastic Syndrome Belonging to the Refractory Anemia Subtype

OBJECTIVES

Tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) are cytokines that play key roles in the myelodysplastic syndrome (MDS). There have been several reports on the presence of genetic polymorphisms in the DNA sequence encoding the leader sequence of the TGF-beta1 protein, located in codon 10 in exon 1 and in the -308 promoter region of TNF-alpha. The objective of this study was to investigate the association between TNF-alpha and TGF-beta1 gene polymorphisms and the susceptibility to MDS and the progression of the disease among patients with MDS belonging to the refractory anemia (RA) subtype.

METHODS

The diagnosis of MDS (n = 50) was based on the FAB criteria. The TNF-alpha genotypes were analyzed by PCR-RFLP and the TGF-beta genotypes were analyzed using an amplification refractory mutation system.

RESULTS AND CONCLUSIONS

Compared with healthy control subjects, patients with RA showed no significant deviations in genotype or allele frequencies of TNF-alpha. The TT homozygosity at codon 10 of TGF-beta1 was significantly higher among patients with bi- or pancytopenia (severe group) than in the patients with anemia only (mild group; odds ratio = 6.99, p = 0.003). These findings suggest that the TGF-beta1 gene polymorphism in codon 10 and the -308 TNF-alpha gene polymorphism do not predispose to the development of RA, but the TGF-beta1 gene polymorphism may affect disease progression.

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.

Interleukin-10 production genotype protects against acute persistent rejection after lung transplantation

BACKGROUND

Our previous studies demonstrated that cytokine gene polymorphisms are related to acute rejection in pediatric heart transplantation; a decreased tumor necrosis factor (TNF)-alpha production genotype combined with an increased or intermediate interleukin (IL)-10 production genotype was associated with the smallest incidence of acute rejection. The objective of this study was to determine whether cytokine genotypes TNF-alpha, IL-10, IL-6, interferon-gamma, and transforming growth factor beta were associated with acute persistent rejection after lung transplantation.

METHODS

Cytokine genotyping was performed in 119 adult lung transplantation recipients who underwent surveillance transbronchial biopsies during their first year after transplantation. We categorized recipients with acute persistent rejection if they had 2 consecutive biopsy specimens at >/=Grade A2 despite anti-rejection treatment. We performed cytokine genotyping using the polymerase chain reaction-sequence specific primers technique, with a commercially available kit.

RESULTS

We analyzed the IL-10 genotype in 116 patients. For the increased IL-10 production genotype, 7 of 20 patients (35%) were persistent rejecters. In comparison, 57 of 96 patients (59%) with intermediate or decreased IL-10 production genotype had acute persistent rejection (p = 0.046). For IL-10 haplotypes associated with intermediate IL-10 production, 30 of 45 patients with GCC/ACC haplotype (67%) had acute persistent rejection compared with 10 of 22 patients with GCC/ATA (45%). In the patients with intermediate IL-10 production, 17 of 22 (77%) with IL-10 GCC/ACC and IL-6 G/C had acute persistent rejection, whereas only 2 of 7 patients (29%) with IL-10 GCC/ATA and IL-6 G/G had acute persistent rejection (p = 0.018).

CONCLUSIONS

In lung transplant recipients, the increased IL-10 production genotype protects against acute persistent rejection when compared with the intermediate or decreased IL-10 production genotypes. The intermediate IL-10 production genotype in lung transplant recipients can be differentiated into 2 haplotype responses, with the GCC/ACC haplotype associated more with acute persistent rejection. In lung transplant recipients, the immunomodulatory effects of IL-6 are differentiated in the G/C and G/G alleles in conjunction with IL-10 haplotypes, with G/C being associated with more acute persistent rejection in conjunction with the IL-10 GCC/ACC haplotype. Future pharmacogenomic models may incorporate these associations with acute persistent rejection in lung transplant recipients to formulate individualized therapeutic regimens.

Cytokine single nucleotide polymorphisms and intrarenal gene expression in chronic allograft nephropathy in children

BACKGROUND

Single nucleotide polymorphisms (SNPs) have been reported to influence cytokine production. Certain cytokine high producer genotypes have been associated with an increased risk for acute rejection and chronic allograft dysfunction (CAD) after transplantation. Our study evaluates SNP distribution for transforming growth factor-beta1 (TGF-beta1), interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-alpha) in pediatric renal transplant recipients and control individuals and correlates them to corresponding intrarenal gene expression.

METHODS

SNPs for TGF-beta1 (codon 10 and 25), IL-10 (positions -1082, -819, -592) and TNF-alpha (position -308) were determined in 30 patients with stable graft function, in 75 patients with CAD, and in 173 control individuals by allele-specific polymerase chain reaction (PCR). Intrarenal cytokine gene expression was studied in 25 biopsies with chronic allograft nephropathy (CAN) and 27 normal kidney specimens by real-time reverse transcription (RT)-PCR.

RESULTS

No difference in allele and genotype frequency was detected in any of the investigated groups. No correlation between genotype and intragraft cytokine gene expression was recognized in CAN patients. However, in normal kidney specimens, the low producer TGF-beta1 genotype at codon 10 was associated with significant lower TGF-beta1 mRNA expression. This association was not found for IL-10 or TNF-alpha.

CONCLUSION

Our results do not support the proposition that certain specific cytokine genotypes for TGF-beta1, IL-10, and TNF-alpha are associated with CAD. Intrarenal cytokine gene expression only correlated to one TGF-beta1 SNP in normal kidney specimens. Since overall TGF-beta1 expression was higher in transplanted patients compared to controls, this suggests that SNPs may not play a significant role once the immune system is activated.

Are cytokine gene polymorphisms related to in vitro cytokine production profiles?

Currently, there is much interest in the genetic basis for diseases or disease manifestations and, in particular, in whether they are related to cytokine gene polymorphisms. It has become accepted to denote such single-nucleotide polymorphisms of cytokine genes by their presumed association with high or low in vitro cytokine production. In this article, we analyze the relationship between cytokine gene polymorphisms and in vitro tumor necrosis factor alpha (TNFalpha), interferon gamma (IFNgamma), and interleukin (IL)-10 and IL-13 production, both in liver transplant recipients and in healthy volunteers. The evaluated cytokine gene polymorphisms involved TNF-A-308; TNF-d3; IFN-G+874; IL-10-1082, -819, and -592; and IL-13+2043, and -1055. For healthy volunteers, we observed a relationship between polymorphisms of TNF-d3 and IL-10-1082 with in vitro production of TNFalpha and IL-10, respectively, whereas no significant associations were found for the other tested cytokine gene polymorphisms. For liver transplant recipients, no significant relationship could be established between any of the cytokine gene polymorphisms and in vitro production of corresponding cytokines. Also, we reviewed the literature for the association between cytokine gene polymorphisms and in vitro cytokine production in various patient groups and healthy volunteers. We found that the cellular sources, from which the cytokines were released into the culture supernatant, were different between studies. They were either whole blood, isolated monocytes, or peripheral blood mononuclear cells (PBMC). Also, the in vitro incubation protocol varied to a great extent between studies. This applied for the used in vitro stimulant, the concentration of a particular stimulant, and the length of the incubation period. Moreover, the study populations were either healthy individuals or very diverse patient groups. Therefore, it was impossible to evaluate whether in vitro cytokine production profiles really can be deduced from a particular cytokine gene polymorphism. Given the inconclusive findings, we propose to set up a multicenter workshop in which the relationship between certain cytokine gene polymorphisms and in vitro cytokine production is analyzed, using an identical in vitro cell culture system and study population. Furthermore, we suggest that cytokine gene polymorphisms be described by their localization within the gene or gene-promoter, rather than by their presumed in vitro cytokine production profile, to properly evaluate the relationship between cytokine gene polymorphisms and disease manifestations.

Genetic Polymorphisms in Cytokine and Adhesion Molecule Genes in Coronary Artery Disease

Both inflammation and genetics play an important role in the pathogenesis of atherosclerosis and coronary artery disease. Epidemiological studies have investigated the association between coronary artery disease (CAD) and gene polymorphisms of the inflammatory molecules tumor necrosis factors (TNF) alpha and beta, transforming growth factors (TGF) beta-1 and beta-2, interleukin (IL)-1 and its receptor antagonist (IL-1ra), CD14 (the receptor for lipopolysaccharide), P- and E-selectins, and platelet endothelial cell adhesion molecule (PECAM)-1. Current evidence suggests that the TNF polymorphisms explored so far are not linked to CAD. The majority of studies conducted showed no significant association between TGFbeta-1 and coronary atherosclerosis, but the data currently available are somewhat controversial. Some polymorphisms may increase the risk of myocardial infarction (MI) within specific ethnic groups or in certain populations. The association between the IL-1 system and atherosclerosis is complex and may vary as a result of a number of factors, such as stage of disease, clinical phenotype, and possibly population characteristics. The E-selectin gene (SELE) Arg128, 98T, and Phe554 alleles may increase the risk of atherosclerosis, but not necessarily the risk of MI. This association seems to be more pronounced in younger patients. The PECAM1 Leu125Val and Ser563Asn polymorphisms may increase the risk of atherosclerosis but not necessarily of MI. This association may be especially important in patients with a low risk for developing atherosclerosis. Current data indicate that screening for CD14-260C/T genotypes is unlikely to be a useful tool for risk assessment and it remains unclear whether CD14 polymorphisms significantly increase the risk of MI. The associations between candidate gene polymorphisms and CAD are complex as a consequence of pleiotropy, variations with age, selection due to the high lethality of the disease, and interactions with other genes and environmental factors. Nonetheless, although the current data is preliminary and partly conflicting, it does provide some evidence that alterations in the genetics of the inflammatory system may modify the risk of CAD.

Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

A number of genetic polymorphisms have been shown to regulate the production and secretion of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. Several of these genetic polymorphisms have been shown to be associated with either acute or chronic rejection of kidney, liver, and heart allografts and with development of allograft fibrosis after lung transplantation. The aim of this study was to assess the effect of these genetic polymorphisms on the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Genetic polymorphisms were detected by means of polymerase chain reaction in 93 lung allograft recipients for functional polymorphisms in the TNF-alpha (-308), TGF-beta1 (+869 and +915), IL-6 (-174), IFN-gamma (+874), and IL-10 (-1082, -819, and -592) genes. Then, a correlation between BOS development and the presence of these cytokine genotypes was determined using Kaplan-Meier actuarial analysis.

RESULTS

A significant correlation was detected between the presence of high-expression polymorphisms of the IL-6 and IFN-gamma genes and BOS development after lung transplantation (P =0.045 and 0.039, respectively). Also, patients with high-expression polymorphisms in both genes developed BOS significantly earlier than patients with low-expression polymorphisms in one or both genes, suggesting a synergistic effect of the alleles during BOS pathogenesis (P =0.016). No correlation was detected between polymorphisms of the TNF-alpha, TGF-beta1, and IL-10 genes and development of BOS after lung transplantation.

CONCLUSIONS

The presence of high-expression polymorphisms at position -174 of the IL-6 gene and position +874 of the IFN-gamma gene significantly increases the risk for BOS development after lung transplantation.

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.

Tumor necrosis factor-alpha in cardiovascular biology and the potential role for anti-tumor necrosis factor-alpha therapy in heart disease

The functional role of tumor necrosis factor (TNF)-alpha in the heart has been extensively studied over the last 15 years. Collectively, these studies have demonstrated that TNF-alpha has both diverse and potentially conflicting roles in cardiac function and pathology. These include beneficial effects, such as cardioprotection against ischemia, myocarditis, and pressure overload, as well as potentially adverse effects, such as the development of atherosclerosis, reperfusion injury, hypertrophy, and heart failure. TNF-alpha antagonist therapy recently has been demonstrated to be clinically applicable in inflammatory conditions, and clinical trials are currently in progress in the use of these agents in cardiovascular diseases. The scope for clinical applications of anti-TNF-alpha therapy in cardiovascular diseases is potentially extensive. Hence, this review has been undertaken to evaluate the cardiovascular effects of this pleiotropic cytokine and to evaluate the potential of targeting this cytokine in cardiovascular therapeutics. An overview of the TNF-alpha peptide and its associated signaling are described. This is followed by a discussion of the known roles of TNF-alpha in cardiac physiology and in a diverse array of cardiac pathologies. Reference to experimental and clinical studies using anti-TNF-alpha therapies are described where applicable. The postulated role of TNF-alpha signaling concerning innate cardiac cellular processes that may have direct adaptive effects in the heart will be reviewed with respect to future research directions. Finally, the author postulates that attenuation of TNF-alpha biosynthesis in selected individuals will need to be tested if true benefits of this therapeutic approach are to be realized in the management of cardiovascular diseases.

Influence of TNFalpha gene polymorphisms on TNFalpha production and disease

Tumor necrosis factor alpha (TNFalpha) is a potent inflammatory cytokine. In human, the TNFalpha gene is located within the highly polymorphic major histocompatibility complex (MHC) region on chromosome 6p21.3. TNF gene cluster contains many polymorphisms including microsatellites and single nucleotide polymorphisms (SNPs). Many of these polymorphisms were found to be in linkage disequilibrium with HLA class I and II alleles. Some of the TNFalpha gene polymorphisms were found to influence TNFalpha production in vitro, for example the -308 SNP. Many studies have shown that this SNP and others within the TNFalpha gene associate with different inflammatory conditions. Whether this phenomenon is due to the direct influence of the SNP in question and/or due to linkage disequilibrium with other polymorphisms within the TNFalpha gene or the HLA system is still controversial.